Methods of identifying a characteristic of a clinical analysis specimen or a sample container containing the specimen are disclosed. The methods include moving the sample container along a track while causing translation and rotation of the sample container, and capturing two or more images of the sample container during the translation and rotation. The track may have one or more moveable belts contacting a carrier to rotate and translate the carrier holding the sample container. Image analysis may be used to read a barcode label of the sample container, determine HIL, and/or physical characteristics of the sample container. Apparatus for carrying out the method are described, as are other aspects.

A wide variety of automated chemical analyzers are used to analyze patient specimens. These clinical analyzers may conduct assays using reagents to identify one or more analytes in, or characteristics of, a biological liquid such as urine, blood serum or plasma, cerebrospinal liquids, and the like. For convenience and safety reasons, these biological liquids may be contained within sample containers (e.g., sample tubes) that are generally capped.
Improvements in clinical analyzer technology have been accompanied by advances in pre-analytical sample preparation and handling operations such as sample sorting, sample container centrifugation, cap removal, and the like by automated pre-analytical sample preparation systems called Laboratory Automation Systems (LASs). LASs automatically transport biological liquid samples in sample containers to a number of sample processing stations that have been linked together. These LASs may handle a number of different patient specimens contained in standard, barcode-labeled, and evacuated sample containers. The barcode label may contain an accession number that may be correlated to demographic information that may be entered into a hospital's Laboratory Information System (LIS) along with test orders and other desired information. An operator may place the labeled sample containers (e.g., sample tubes) onto the LAS system, which may automatically route the sample containers for pre-analytical operations such as centrifugation, decapping, and aliquot preparation, prior to the specimen being subjected to clinical analysis by one or more analytical stations that may also be linked to, or part of, the LAS.
For certain clinical assays, a serum or plasma portion (obtained from whole blood by centrifugation) may be used. To prevent clotting, an anticoagulant such as citrate or heparin may be added to the blood specimen. After centrifuging and subsequent de-capping, the open sample container (e.g., tube) may be transported to an appropriate clinical analyzer that may extract liquid specimen from the sample container and combine the specimen with one or more reagents in reaction containers (e.g., cuvettes or cups). Analytical measurements may then be performed, using, for example, photometric or fluorometric absorption readings or the like. The measurements allow determination of values from which an amount of analyte related to the health of the patient may be determined using well-known techniques. Unfortunately, the presence of certain components (e.g., interferents) such as hemolysis (ruptured red blood cells), icterus (excessive bilirubin), and lipemia (high, visible lipid content) (hereinafter "HIL") in the specimen as a result of some preexisting sample condition or processing may adversely affect an accuracy of the analyte measurement obtained from the clinical analyzer.
In some cases, the integrity of the serum or plasma portion of the specimen may affect the interpretation of the results, i.e., the analyte reading of the clinical analyzer. For example, pre-analytical variables in the serum or plasma portion, which are not related to the patient disease state, may cause a different interpretation of the disease condition of the patient. Pre-analytical variables include HIL. Typically, the integrity of the serum or plasma portion of the specimen is visually inspected by a skilled laboratory technician. This may involve a review of the color of the serum or plasma portion of the specimen. A normal serum or plasma portion has a light yellow to light amber color.
A serum or plasma portion containing hemolysis may be quite reddish in color. Interferents may arise, for example, if an excess number of red blood cells are damaged, possibly during venipuncture, centrifugation, or prolonged storage. When red blood cells are injured, they release low density, reddish-colored hemoglobin into the specimen causing a reddish-colored sample that is said to exhibit "hemolysis." The presence of free hemoglobin may be used to measure the degree of hemolysis and, when the hemoglobin concentration exceeds about 20 mg/dl, the hemoglobin may interfere with the colorimetric determination of analytes in the clinical analyzer due to the reddish interferent contained in the specimen.
A sample containing icterus may be dark yellow/brown in color. Such interferents may arise, for example, from an excess of bilirubin, the result of decaying red blood cells being converted in the spleen into bilirubin. Levels of bilirubin above 2-3 mg/dl are visibly yellowish and may, in particular, adversely affect enzyme-based immunoassays. Such a condition is termed bilirubinaemia or icterus.
A sample containing lipemia may be whitish in color. Interferents may arise, for example, as a whitish appearance in serum or plasma portion due to the presence of excess lipids. Such a condition is called lipemia and lipid levels above about 50 mg/dl may interfere with antibody binding in immunoassays and may, accordingly, affect immunoassay results.
Thus, the degree of red color in a serum or plasma portion may correspond to the amount of hemolysis present, the degree of dark yellow/brown color may correspond to the amount of icterus present in the serum or plasma portion of the specimen, and the degree of whitish color may correspond to the amount of lipemia present in the serum or plasma portion of the specimen.
Subsequent to centrifugation, when the red blood cell portion has been separated from the serum or plasma portion, a skilled technician may visually inspect the serum or plasma portion and, if judged to not have a normal light yellow to light amber color, the specimen may be rejected. Otherwise, the specimen will be processed and analyzed as ordered. However, visual inspection is very subjective, labor intensive, and fraught with the possibility of human error. Thus, various methods have been implemented to ascertain whether hemolysis, icterus, and lipemia (these three conditions are frequently called "HIL") are present in a serum or plasma portion of the specimen.
Typically, a laboratory technician will assign a hemolytic index, an icteric index, and a lipemic index to the serum and plasma portion based upon the color. Based upon the value of the hemolytic index, the icteric index, and the lipemic index, the interpretation of the results from the clinical analyzer can be evaluated. Alternately, if the value of one or more of the indexes is too high, the specimen may be rejected without analysis by the clinical analyzer. As mentioned above, visual inspection can be labor intensive and costly. Furthermore, the possibility of human error exists with visual inspection, the results of the visual inspection may be highly subjective and may vary between workers, and one variable could mask or hide other variables. Thus, it is becoming increasingly important to evaluate the integrity of the serum or plasma portion of the specimen without the use of visual inspection by a laboratory technician.
One attempt to solve this problem involves optically viewing the serum or plasma portion of the specimen after the specimen is transferred to one of the cuvettes of the clinical analyzer. Measuring the optical characteristics of the specimen in the clinical analyzer eliminates the need for visual inspection, but utilizes time on the clinical analyzer and, if the integrity of the specimen is determined to be compromised, additional machine time and a machine cycle is wasted. Furthermore, this procedure cannot be used with clinical analyzers that add reagents to the cuvette prior to adding the serum or plasma portion of the specimen.
One challenge in performing spectrophotometric analysis is that the specimens are initially obtained in a variety of types/sizes of primary patient sample collection containers ("sample containers"). These sample containers are usually tubes of varying diameters and lengths. In the case of a patient blood specimen, the liquid is often centrifuged to separate the serum or plasma portion from the cellular phase (e.g., red blood cell portion). Such sample containers may have a patient identification label, varying and unpredictable amounts of the serum or plasma portion, and can contain a varied amount of specimen liquid.
Because of the problems encountered when interferents are contained in specimens to be analyzed, there is an unmet need for methods and apparatus adapted to rapidly determine a presence of such interferents. The method and apparatus should not appreciably adversely affect the speed of obtaining analytical test results and should be deployable early in the processing so that corrective action by laboratory personnel minimizes delays in patient sample analysis. Furthermore, the method and apparatus should be able to be used on labeled sample containers.

Methods and apparatus for ascertaining specimen and/or sample container characteristics while in transit


A plurality of control processors distribute data to be processed to a corresponding plurality of arithmetic processors using a dynamic allocation arrangement. The arithmetic processors process blocks of information and communicate the blocks of processed information to the control processors for subsequent processing as necessary. The control processors are implemented to efficiently allocate tasks to the arithmetic processors and to partition blocks of data for allocation as separate partitioned tasks to the arithmetic processors. This partitioning of blocks of data to be processed as partitioned tasks significantly reduces the delay until the results are available by distributing the task over a plurality of arithmetic processors. It also significantly improves utilization of processing resources by assigning the task to a plurality of processors that may be available.

The present invention relates generally to computer systems, and in particular, to task allocation for improved multi-processor system operation.
Related art includes multi-processor systems having dynamic allocation of resources. Multi-processor systems having dynamic allocation of resources in general are old in the art. The article entitled "Signal Processing Through Macro Data Flow Architecture" by Plan et al, 1985 NAECON Proceedings, which is herein incorporated by reference, provides an overview of a multi-processor system.
Multi-processor systems combine multiple processors to gain increased processing bandwidth. However, the efficiency of such systems is significantly reduced by inefficient resource management implementations. For example, a high processing bandwidth capability may be only partially utilized if the processor is waiting for task assignments or waiting for data. Task assignments have been improved with dynamic allocation algorithms and data availability is improved with buffer memories, such as FIFOs, stacks, and cache memories. However, significant inefficiencies still exist. For example, one processor may be performing complex processing operations on an array of data while other processors are available for processing.
The Motorola 68000 microprocessor family includes many important processor features, such as stack, queue, and flag related operations, buses and dedicated input and output channels, and cache memory. See the "Motorola M68000 Programmer's Reference Manual", Prentice-Hall (1984), and the "MC68020 32-Bit Microprocessor User's Manual", Prentice-Hall (1984), which are herein incorporated by reference.

Dynamic task allocation in a multi-processor system employing distributed control processors and distributed arithmetic processors


A superconducting coil is mounted on a permanent non-magnetic coil form by first winding an unreacted wire onto a temporary coil form made of refractory materials which can be assembled and disassembled, reacting the wound unreacted wire at high temperatures to form a superconducting coil. The temporary coil form is disassembled and the superconducting coil is transferred to a permanent coil form made of a non-magnetic material. The temporary coil form includes a bore tube and an end flange made of a refractory material and a terminal flange made of a non-magnetic refractory material. The terminal flange is removably secured to the bore tube. The end flange is positioned next to the other end of the bore tube and held in position against the tube by means of an end plate. A terminal plate is removably positioned adjacent to the bore tube. The assembly is held together by means of an axial force on the terminal and end plates. The superconductor wire can be wound around the outer surface of the bore tube to form a superconducting coil.

A class of superconducting magnet generating a highly uniform field is required for nuclear magnetic resonance (NMR) spectroscopy. The uniformity of the field requires accurate positioning of the turns of the superconductor coil in a precisely defined geometry. It also requires that proximity of the superconducting coil with materials having a magnetic susceptibility greater than zero be avoided. Thus, all ferrous alloys, including so-called "non-magnetic" stainless steel, must be eliminated from the structure and windings of the NMR magnet.
High field superconducting magnets typically use niobium-tin superconductor. The superconductor is wound in the form of a wire in which the component niobium and tin are in the unreacted state. The superconducting wire is wound around a form of suitable geometry to provide a superconducting coil. The form and coil are heated to approximately 700.degree. C., thereby forming the superconducting intermetallic niobium-tin compound, Nb.sub.3 Sn, mounted on the coil form. The high temperature reaction requires the use of refractory materials for the forms upon which the superconducting wire is coiled and heated. Copper, aluminum and their alloys, suitable for magnet applications, are unsuitable because of softening or melting near 700.degree. C. Similarly, organic materials can not be used. A refractory material, i.e., stainless steel, are preferred for the high temperature reaction of the superconducting coil but are unsuitable for NMR magnet applications. A stainless steel form is preferred for the high temperature reaction of the superconducting coils, while a non-magnetic material is preferred for the magnetic applications of the superconducting coils.
It is an object of the present invention to provide a superconducting coil and method for its manufacture on a non-magnetic form which does not disrupt the magnetic field of the superconducting magnetic.
It is a further object of the present invention to provide a coil form which is capable of assembly and disassembly and suitable for use at high temperatures for the preparation of superconducting coils.

Removable coil form for superconducting nmr magnets and a method for its use


This invention provides a system and method for positioning, manipulating, holding, grasping, immobilizing and/or stabilizing a heart including one or more tissue-engaging devices, one or more suction sources, one or more fluid sources, one or more energy sources, one or more sensors and one or more processors. The system and method may include an indifferent electrode, a drug delivery device and an illumination device. The system's tissue-engaging device may comprise a tissue-engaging head, a support apparatus and a clamping mechanism for attaching the tissue-engaging device to a stable object. The system may be used during various medical procedures including the deployment of an anastomotic device, intermittently stopping and starting of the heart, ablation of cardiac tissues and the placement of cardiac leads.

Coronary artery disease remains the leading cause of morbidity and mortality in Western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow to various areas of the heart. This can lead to the discomfort of angina and the risk of ischemia. In severe cases, acute blockage of coronary blood flow can result in irreversible damage to the myocardial tissue including myocardial infarction and the risk of death.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to merely treat the symptoms, with pharmaceuticals, or treat the underlying causes of the disease, with lifestyle modification. In more severe cases, the coronary blockage can be treated endovascularly or percutaneously using techniques such as balloon angioplasty, atherectomy, laser ablation, stents, and the like.
In cases where these approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft (CABG) procedure. CABG surgery, also known as "heart bypass" surgery, generally entails the use of a graft or conduit to bypass the coronary obstruction and, thereby provide blood flow to the downstream ischemic heart tissues. The procedure is generally lengthy, traumatic and subject to patient risk. Among the risk factors involved is the use of a cardiopulmonary bypass (CPB) circuit, also known as a "heart-lung machine", to both pump blood and oxygenate the blood so that the patient's heart may be stopped during the surgery, with its function performed by the CPB circuit.
Conventional CABG procedures are typically conducted on an arrested heart while the patient is on CPB. The CPB circuit provides continuous systemic blood circulation, while cardioplegic cardiac arrest enables meticulous anastomosis suturing in a bloodless, still operative field. In the majority of patients, obstructed coronary arteries are bypassed; for example, with an in situ internal mammary artery (IMA) or a reversed segment of saphenous vein harvested from a leg.
Segments of other suitable blood vessels may also be used for grafting depending on availability, size and quality. In general, the body hosts seven potential arterial conduits, the right and left IMAs, the radial arteries and three viceral arteries, one in the abdomen, and two in the lower abdominal wall, though the latter may be quite short and are generally of limited usefulness. The viceral arteries include the gastroepiploic artery and the splenic artery.
The left IMA is best used for bypass to the left anterior descending (LAD) coronary artery and its diagonal branches. Whereas, the right IMA may be used for bypass to selected vessels more posterior such as the distal right coronary artery (RCA). The right IMA may also be used for bypass to selected marginal branches of the left circumflex coronary artery. A segment of radial artery harvested from an arm is generally used to revascularize the posterior surface of the heart. The right gastroepiploic artery may be used to revascularize almost any artery on the surface of the heart. It is most commonly used for bypass to the distal RCA or the posterior descending coronary artery. In unusual circumstances the splenic artery is used to revascularize posterior coronary arteries, but it is long enough to reach the marginal branches of the circumflex coronary artery.
Surgeons will generally complete bypass grafts to the following coronary arteries in a patient undergoing multiple bypass surgery in roughly the following order: posterior descending coronary artery (PDA), RCA, obtuse marginal branch, circumflex coronary artery, diagonal branch, and LAD. More generally, surgeons will revascularize the three coronary systems in the following order: right, circumflex, and anterior descending. However, the order may vary depending on whether the procedure is performed on a beating heart or an arrested heart. For arrested heart, about 3 to 4 bypass grafts of which 1 to 3 are free grafts are generally performed per procedure. In contrast, about 2 to 3 bypass grafts of which 0 to 2 are free grafts are generally performed per beating heart procedure. In general, 1 free graft is used per beating heart procedure.
When a saphenous vein or other blood vessel is used as a free graft in a procedure, two anastomoses are performed; one to the diseased artery distal to the obstruction (outflow end), and one proximally to the blood vessel supplying the arterial blood (inflow end). These anastomoses are generally performed using end-to-side anastomotic techniques. Rarely an end-to-end anastomotic technique is used. When more than one graft is required in any of the three coronary systems for complete revascularization of the heart, sequential graft techniques may be used to conserve the amount of blood vessels required. Sequential graft techniques use proximal side-to-side anastomoses and an end-to-side anastomosis to complete the graft. For example, a common sequence used in the anterior descending coronary system is a side-to-side anastomosis of graft to the diagonal branch and an end-to-side anastomosis of graft to the LAD coronary artery. However, only a small percentage of anastomoses are side-to-side anastomoses.
The majority of surgeons will complete the distal anastomosis of a graft prior to completion of the proximal anastomosis. The small percentage of surgeons who do complete the proximal anastomosis first usually do so to allow antegrade perfusion of cardioplegic solution through the graft during revascularization. Construction of the distal anastomosis, e.g., a saphenous vein-coronary artery anastomosis, begins by first locating the target artery on the heart. Next, an incision is made through the epicardium and the myocardium to expose the artery. An arteriotomy is then made using a knife to incise the artery. The incision is then extended with a scissors. The length of the incision approximates the diameter of the saphenous vein, about 4 to 5 mm. The diameter of the target artery is generally 1.5 to 2.0 mm. Since, most surgeons currently feel the distal take-off angle should be 30 to 45 degrees, the distal end of the saphenous vein is usually beveled at about 30 to 45 degrees.
Currently, surgeons generally construct the anastomosis via a ten-stitch running suture using 7-0 polypropylene suture material. The ten-stitch anastomosis typically comprises five stitches around the heel of the graft and five stitches around the toe. The five stitches around the heel of the graft comprise two stitches to one side of the apex of the graft and the artery, a stitch through the apex and two stitches placed at the opposite side of the apex. The graft is generally held apart from the coronary artery while the stitches are constructed using a needle manipulated by a forceps. Suture loops are drawn up and the suture pulled straight through to eliminate purse-string effect. The five stitches around the toe of the graft also comprises two stitches to one side of the apex of the graft and the artery, a stitch through the apex and two stitches placed at the opposite side of the apex. Again, suture loops are drawn up and the suture pulled straight through to eliminate purse-string effect. The suture ends are then tied.
The proximal anastomosis of a saphenous vein graft to the aorta, i.e., an aortosaphenous vein anastomosis, is formed by first removing the pericardial layer that covers the aorta. An occluding or side-biting clamp may be placed on the aorta at the anastomosis site or an aortotomy occlusion device may be used following creation of the aortotomy. A small circular or elliptical portion of the ascending aorta is excised forming a small opening 4 to 5 mm in diameter, i.e. the aortotomy. An aortic punch typically facilitates this procedure. The opening for a right-sided graft is made anterior or to the right lateral side of the aorta, whereas an opening for a left-sided graft is made to the left lateral side of the aorta. If the graft is to supply blood to the right coronary artery, the opening is generally made proximal on the aorta. If the graft is to supply blood to the anterior descending coronary artery, the opening is generally made in the middle on the aorta. And, if the graft is to supply blood to the circumflex artery, the opening is generally made distal on the aorta. The right graft opening is placed slightly in the right of the anterior midpoint of the aorta and the left graft opening slightly to the left. The end of the saphenous vein is cut back longitudinally for a distance of approximately 1 cm. A vascular clamp is placed across the tip of the saphenous vein to flatten it, thereby exposing the apex of the vein. Five suture loops of a running suture using 5-0 polypropylene are then placed around the 'heel' of the graft and passed through the aortic wall. Two stitches are placed on one side of the apex, the third stitch is placed precisely through the apex of the incision in the saphenous vein, and the final two stitches are placed on the opposite side of the apex. Suture traction is used to help expose the edge of the aortic opening to ensure accurate needle placement. Stitches include about 3 to 5 mm of the aortic wall for adequate strength. Suture loops are then pulled up to approximate the vein graft to the aorta. The remaining stitches are placed in a cartwheel fashion around the aortic opening thereby completing the remainder of the anastomosis.
Left-sided grafts are oriented so the apex of the incision in the "heel" of the saphenous vein will face directly to the left side. The stitches are placed in a clockwise fashion around the heel of the graft and in a counterclockwise fashion around the aortic opening. Right-sided grafts are oriented in a caudal fashion. The stitches are placed in a counterclockwise fashion around the heel of the graft and in a clockwise fashion around the aortic opening. Five suture loops complete the heel portion of the graft and an additional five or six are necessary to complete the toe of the graft. Finished proximal anastomoses typically have a "cobra-head" appearance.
It is essential for the surgeon to take steps to minimize the possibility of thrombosis, narrowing and/or premature closure of the anastomosis due to technical errors. Some surgeons feel the proximal anastomosis must have a take-off angle of 45 degrees while other surgeons believe the take-off angle is not critical. In addition, it was felt that intima-to-intima contact of the vessels at the anastomosis was critical for endothelization to occur, thereby making an ideal union of the vessels. However, most surgeons now feel intima-to-adventitia contact is acceptable. The main objective of the surgeon is to create an anastomosis with an expected long-term patency rate of greater than 5 to 10 years. The creation of an anastomosis currently takes approximately 10-15 minutes.
One essential requirement for creating an anastomosis without error is adequate exposure of the target vessel. Acute visualization of the vessel walls is mandatory in order to properly place each stitch and avoid inadvertently including the back wall of the vessel in a stitch, which in effect narrows or completely occludes the vessel. In order to achieve the required exposure most surgeons will employee blood-less field devices such as shunts, snares, and misted blowers. Further, largely invasive surgical techniques are also employed to help the surgeon gain access to the grafting site. For this reason, CABG surgery is typically performed through a median sternotomy, which provides access to the heart and to all major coronary branches. A median sternotomy incision begins just below the sternal notch and extends slightly below the xiphoid process. A sternal retractor is used to spread the left and right rib cage apart for optimal exposure of the heart. Hemostasis of the sternal edges is typically obtained using electrocautery with a ball-tip electrode and a thin layer of bone wax. The pericardial sac is opened thereby achieving direct access to the heart.
A blood vessel or vessels for use in the graft procedure are mobilized from the patient. This usually entails mobilizing either a mammary artery or a saphenous vein, although other graft vessels as discussed above may also be used. A heart-lung or cardiopulmonary bypass is performed. This usually entails arterial and venous cannulation, connecting the bloodstream to a heart-lung machine, cooling the body to about 32 degrees Celsius, cross clamping of the aorta and cardioplegic perfusion of the coronary arteries to arrest and cool the heart to about 4 degrees Celsius. A proximal anastomosis may be performed on partial bypass using a partial occluding aortic cross-clamp or side-clamp. The arrest or stoppage of the heart is generally required because the constant pumping motion of the beating heart would make surgery upon the heart difficult in some locations and extremely difficult if not impossible in other locations
Once cardiac arrest is achieved, then a graft (or grafts) is attached to the relevant portions of a coronary artery (or arteries) followed by weaning from the cardiopulmonary bypass, restarting the heart and decannulation. Finally the chest is closed.
Problems that may be associated with conventional CABG procedures with CPB include the initiation of a systemic inflammatory response due to the interactions of blood elements with the artificial material surfaces of the CPB circuit. Global (hypothermic) cardiac arrest may result in global myocardial ischemia and cross clamping the ascending aorta may contribute to the patient experiencing a post-operative stroke. In fact, recent studies have shown aortic clamping and manipulation may release atherosclerotic debris into the bloodstream, resulting in neurologic injury.
Currently, the golden standard for creation of a vascular anastomosis is manual suturing. Manual suturing may be used to attach vascular grafts (either autografts or prosthetic grafts) for coronary bypass, femoral-femoral bypass (to relieve inadequate circulation in the legs), and AV fistulas and/or shunts (access portals for repeated puncture applications such as kidney dialysis or diabetes). However, a number of cardiac surgical procedures, e.g., off-pump, beating heart CABG procedures, minimally invasive procedures and even totally endoscopic procedures with access through ports only, may require a variety of new anastomotic techniques. The ability of performing anastomoses with limited or no CPB support may increase the possibility of performing more CABG procedures using minimally invasive surgical techniques. Avoiding the use of cross clamps and CPB or dramatically reducing pump run and cross clamp times may effectively minimize post-operative complications. For this reason, there is an increasing need for easier, quicker, less damaging, but reliable automated, semi-automated, or at least facilitated methods to replace or enhance the normal process of a manually sutured vascular anastomosis.
The major objective of any CABG procedure is to perform a technically perfect anastomosis. However, creation of a technically perfect anastomosis is generally complex, tedious, time consuming and its success is highly dependent on a surgeon's skill level. Therefore, creation of vascular anastomoses without the need to perform delicate and intricate suture lines may enable surgeons to more quickly create simpler and effective anastomoses. Currently, there are a number of techniques or procedures being investigated for facilitating the process of forming an anastomosis including vascular clips or staplers, glues, adhesives or sealants, laser welding, mechanical couplers, stents and robot-assisted suturing. These techniques are being developed for performing end-to-end, end-to-side and/or side-to-side anastomoses with or without temporary blood flow interruption. In general, these techniques may include the use of various biomaterials and/or biocompatible agents.
In an effort to reduce or eliminate occlusive anastomosis time, various techniques or procedures are being investigated. These procedures include coronary shunting techniques, which enable manual suturing without time-constraint due to persistent distal perfusion, and accelerated tissue-bonding techniques, e.g., tissue adhesives and laser welding. Some nonocclusive anastomosis techniques being developed require apposition of the intima of the graft to the adventitia of the recipient artery.
Sealants, adhesives or glues may be based on synthetic or biological substances or a combination of both. They are generally used to either seal post-operative internal air or fluid leaks, or to close a topical wound. Surgical sealants are generally absorbable materials used primarily to control internal bleeding and to seal tissue. Surgical adhesives, stronger than sealants, are often non-absorbable, but tend to be biologically based. Surgical glues, stronger than adhesives, are often synthetic and non-absorbable. In addition, glues are often used for topical wounds. Surgical glues are typically made from cyanoacrylates, a strong adhesive found in commercially available super glues. Biologically based sealants, adhesives or glues are generally derived from blood clotting components such as proteins (e.g., fibrinogen or fibrin), enzymes (e.g., thrombin) and/or platelets. Fibrin based sealants, adhesives or glues generally combine the protein fibrinogen with the enzyme thrombin to immediately begin the clotting process. One surgical adhesive currently being marketed includes a combination of collagen (proteins which form fibers to support body tissues), formalin (a form of formaldehyde), resorcinol and glutaraldehyde. Some sealants, adhesives or glues may be used to control bleeding or to reinforce suture or staple lines rather than to make tissues adhere, thus functioning more as hemostatic agents than glues.
There are a number of uses for sealants, adhesives or glues such as replacement for sutures and staples in minimally invasive procedures where the surgeon has little room to maneuver or for the repair of aortic dissections, where the tissue is so thin it may be damaged by sutures. They may also be used for anastomotic sealing, in which the seal should not be absorbed or carotid patching, where a complete seal is desired.
Laser welding is another potential method for forming an anastomosis. Laser welding uses lasers such as CO2 lasers, argon lasers or Neodymium-YAG lasers, to join tissues together thermally instead of, for example, mechanically. One possible mechanism of laser welding of tissues is the thermal denaturation and coagulation of collagen fibrils in the tissue, which generally occur above 60° C. To improve the procedure, photosensitive dyes (e.g., indocyanine green) may be applied at the weld site to enhance light absorption and minimize thermal damage to the surrounding tissue. Using a dye that adsorbs light at a very specific frequency, a laser can be then used to selectively heat the dye and not the surrounding tissue. Photosensitive dyes used in laser welding procedures may or may not bind chemically to the tissue's proteins. Unlike sutures or staples, laser welding may offer a water tight seal to hold bodily fluids in, thereby preventing blood loss, infections and repeat surgeries. A further enhancement to the laser welding technique is to use a "solder". Solders may comprise synthetic and/or biological components. For example, proteins such as albumin have been used in various solder formulations. Typical laser welding devices include one or more flexible optical fibers and solder-delivery tubes that may be snaked through small ports or through a channel in an endoscope.
Mechanical anastomotic devices include stapling devices, clipping devices, ring and pin coupling devices and suturing devices. These anastomotic devices may be automated or semi-automated. Mechanical anastomotic devices also include mechanical couplers including stents, ferrules, and/or rings. Materials used to form an anastomosis via a mechanical device and/or coupler may be biocompatible, bioabsorbable, bioactive and/or bioinert.
One component intra-luminal mechanical anastomotic devices are generally stent-like in design. The graft and the target vessel, i.e., the aorta or coronary artery, are forced into tubular shapes by the device. In general, the application of this type of device is relatively easy. The device can be made to unfold by itself so no deformation forces are necessary at the anastomosis. In addition, angled anastomoses are possible. The device may however have a lot of foreign material exposed within the blood stream, thus increasing the risk of stenosis and thrombosis. In some cases, the device may prevent direct contact between the graft and the target vessel, thereby preventing the vessel walls from healing together. Intimal damage to both the graft and the target vessel may also occur during delivery of the device. Extra sealing methods, e.g., tissue sealants, may be necessary to provide a leak-free anastomosis. In addition, the size of the device is strongly related to the size of the vessels. Therefore, a range of devices and measurement of the vessels is necessary.
Two component intra-luminal mechanical anastomotic devices require both the graft and the target vessel to be connected to their own coupling component, after which the two coupling components are connected to each other, thereby forming the complete anastomosis. Problems associated with construction of an anastomosis using a two component intra-luminal mechanical coupling device include mounting of the vessels and connection of the components. Tools for mounting the individual coupling components to each vessel and tools for connecting the coupling components together are both required.
One component extra-luminal mechanical anastomotic devices generally require a delivery tool to position the coupling device in the recipient vessel. One component extra-luminal mechanical coupling devices generally allow direct intima-to-intima contact. In addition, this type of device will have less foreign material in the blood stream, thereby decreasing the risk of stenosis and thrombosis. For this reason, less biological testing may be required as opposed to an intra-luminal stent-like device. However, mounting of the graft to the coupling device may not be easy. Damage may occur due to everting of the graft onto the device. For example, everting of a graft onto a device may cause damage to the intimal layer. This damage may occur for two reasons: 1) solid grabbing of the vessel wall is necessary to evert an artery, thus one tip of the pair of pincers will roughly touch the intima; and, 2) eversion causes high strain (stretching), which will damage the arteries. Another problem is that skills are still necessary for proper eversion. The surgeon has to estimate where to grab the vessel wall and how to lift it over one of the pins to obtain a symmetrical anastomosis. A specially designed mounting tool may make the step of mounting the graft onto the coupling device easier and may help to minimize damage to the graft. In addition, care must be taken to avoid compression of tissue by the coupling device since compression can cause pressure necrosis.
Two component extra-luminal mechanical anastomotic devices, like the two component intra-luminal mechanical coupling devices, require both the graft and the target vessel to be connected to their own coupling component, after which the two coupling components are connected to each other, thereby forming the complete anastomosis. Problems associated with construction of an anastomosis using a two component extra-luminal mechanical coupling device also include mounting of the vessels and connection of the components. Tools for mounting the individual coupling components to each vessel and tools for connecting the coupling components together may be required.
Hybrid anastomosis techniques combine one or more techniques, e.g., sutures or clips with glues or laser welding. A specific example of a hybrid anastomotic technique is the use of an intraluminal stent like device combined with an extraluminal application of biological glue.
One area which may create difficulties for the patient and extra expense and time for a stopped heart CABG procedure involves CPB. In a CPB procedure all the patient's blood, which normally returns to the right atrium, is diverted to a system which supplies oxygen to the blood and removes carbon dioxide from the blood and returns the blood, at sufficient pressure, into the patient's aorta for further distribution into the body. Generally such a system requires several separate components, including an oxygenator, several pumps, a reservoir, a blood temperature control system, filters as well as flow, pressure and temperature sensors.
Problems may develop during cardiopulmonary bypass due to the reaction blood has to non-endothelially lined surfaces, i.e. surfaces unlike those of a blood vessel. In particular, exposure of blood to foreign surfaces results in the activation of virtually all the humoral and cellular components of the inflammatory response, as well as some of the slower reacting specific immune responses. Other complications from cardiopulmonary bypass include loss of red blood cells and platelets due to shear stress damage. In addition, cardiopulmonary bypass requires the use of an anticoagulant, such as heparin. This may, in turn, increase the risk of hemorrhage. Finally cardiopulmonary bypass sometimes necessitates giving additional blood to the patient. The additional blood, if from a source other than the patient, may expose the patient to blood born diseases.
Due to the risks incurred during cardiopulmonary bypass, others have attempted to perform a coronary artery bypass graft procedure without cardiac arrest and cardiopulmonary bypass. For example, Trapp and Bisarya in "Placement of Coronary Artery Bypass Graft Without Pump Oxygenator", Annals Thorac. Surg. Vol. 19, No. 1, (January 1975) pgs. 1-9, immobilized the area of the bypass graft by encircling sutures deep enough to incorporate enough muscle to suspend an area of the heart and prevent damage to the coronary artery. More recently Fanning et al. in "Reoperative Coronary Artery Bypass Grafting Without Cardiopulmonary Bypass", Annals Thorac. Surg. Vol. 55, (February 1993) pgs. 486-489 also reported immobilizing the area of the bypass graft with stabilization sutures.
Suction stabilization systems, such as the Medtronic Octopus® Tissue Stabilizer and Accessories (available from Medtronic, Inc., Minneapolis, Minn. USA), the current model being designated the "Octopus 3™ stabilization system", use suction to grip and immobilize the surface of the heart. Additionally, the system allows the surgeon to manipulate the anastomosis site into better view by rotating and supporting the heart. See, also, e.g., U.S. Pat. Nos. 5,836,311; 5,927,284 and 6,015,378, and co-assigned U.S. patent applications Ser. No. 09/396,047, filed Sep. 15, 1999, Ser. No. 09/559,785, filed Apr. 27, 2000, and Ser. No. 09/678,203, filed Oct. 2, 2000; and European Patent Publication No. EP 0 993 806. The Octopus™ stabilizer facilitates moving or repositioning the heart to achieve better access to areas which would otherwise be difficult to access, such as the posterior or backside of the heart.
It would be desirable to have an organ positioning system and method that comprises a device that engages organ tissue and allows a surgeon to easily position, manipulate, stabilize and/or hold an organ during a medical procedure.
It would further be desirable to have an organ positioning system and method that comprises a device that engages organ tissue and allows a surgeon to easily position, manipulate, stabilize and/or hold an organ during an ablation procedure.
It would be desirable to have an organ positioning system and method that comprises a device that engages organ tissue and allows a surgeon to easily position, manipulate, stabilize and/or hold an organ during an anastomotic procedure.
It would be desirable to have an organ positioning system and method that comprises a device that engages organ tissue and allows a surgeon to easily position, manipulate, stabilize and/or hold an organ during a controlled intermittent asystole procedure.
It would further be desirable to have an organ positioning system and method that comprises a device that engages organ tissue and allows a surgeon to easily position, manipulate, stabilize and/or hold organ tissue during a medical procedure, thereby providing adequate exposure, e.g., adequate visualization and/or access, to a surgical site.
It would further be desirable to have an organ positioning system and method that allows the organ, for example, heart to be positioned in a desired orientation but otherwise allowing movement of the heart as the heart beats.
It would further be desirable to have an organ positioning system and method that is designed to be relatively atraumatic to tissue.
It would further be desirable to have an organ positioning system and method which is capable of positioning, manipulating, stabilizing and/or holding an organ and/or tissue while controllably monitoring one or more chemical, physical or physiological characteristics of a bodily tissue or fluid during a medical procedure.
It would further be desirable to have an organ positioning system and method which is capable of positioning an organ and/or tissue while controllably providing suction during a medical procedure.
It would further be desirable to have an organ positioning system and method which is capable of positioning, manipulating, stabilizing and/or holding an organ and/or tissue while controllably providing fluid during a medical procedure.
It would further be desirable to have an organ positioning system and, method which is capable of positioning, manipulating, stabilizing and/or holding an organ and/or tissue while controllably providing energy during a medical procedure.
It would further be desirable to have an organ positioning system and method which is capable of positioning, manipulating, stabilizing and/or holding an organ and/or tissue while controllably providing illumination during a medical procedure.

Method and system for organ positioning and stabilization


A soundboard for a musical instrument having a body, a rear plate, and a lateral plate, with the soundboard, the rear plate, and the lateral plate defining a sound chamber for the musical instrument. The soundboard extends along a longitudinal axis and has a thickness. The soundboard also has a partial taper recurve asymmetrically disposed around the longitudinal axis. The recurve includes a first recurve section that forms a downward ramp which starts flush with the thickness of the soundboard, a second recurve section that defines the full depth of the partial taper recurve, and a third recurve section that forms an upward ramp which ends flush with the thickness of the soundboard. Also disclosed is a musical instrument comprising the soundboard. The musical instrument may be a guitar.

Music plays an important role in our daily lives and is woven into the fabric of society. Many people perform music as a pastime, a hobby, or an occupation. One of the main divisions of instruments, chordophone instruments are musical instruments that make sound by way of a vibrating string or strings stretched between two points. Chordophone instruments, and in particular stringed musical instruments, are very popular worldwide because they are versatile and suited to different genres of music. The most popular of the stringed musical instruments is probably the modern guitar, including both acoustic guitars which project sound acoustically and electric guitars which project sound through electrical amplification.
Conventional acoustic and electric guitars include a body and a neck that is attached to the body via a joint, with one or more elongate, flexible strings extending between the body and a distal end of the neck along a fretboard. (The terms "distal" or "distal end" are used to define the part or surface of an element which is positioned furthest from the user.) The body has a top surface called a soundboard, typically made from wood, that vibrates when the instrument is played. To provide an instrument with the most aesthetically pleasing tones, soundboards are usually tapered or feathered to thin the soundboard near its peripheral edge to allow more (freer) movement by the soundboard relative to the side wall of the instrument. Thus, the soundboard is tapered from its center to the periphery. The process of tapering a soundboard is difficult and time consuming, however, and frequently requires hours of hand sanding by a skilled craftsman (a luthier) to form a taper at the edges of the soundboard which is not visually apparent (i.e., the surface of the soundboard preferably has a flat appearance). Errors in the tapering process can result in uneven tapering or undesirably thin portions which can lead to cracking and breaking.
Therefore, one disadvantage associated with conventional soundboards is the difficult and time-consuming process of tapering a soundboard. Another disadvantage associated with conventional soundboards is the high cost of tapering a high-quality instrument soundboard. Yet another disadvantage associated with conventional soundboards involves the use of wood as a soundboard material. Wood soundboards tend to swell under humid conditions, causing changes in the visual appearance and tonal quality. In addition, cracking can occur in wood soundboards under dry conditions.
U.S. Pat. No. 6,759,581 issued to Taylor-Listug, Inc. and titled "Acoustic Stringed Instrument Body with Relief Cut" attempts to address the disadvantages highlighted above. As the title implies, provided is an acoustic stringed instrument body including a soundboard with a symmetrical relief cut around its periphery. The relief cut is located on the exterior or interior surface of the soundboard close to the perimeter of that surface. The relief cut may be in other locations, however, including closer to the sound hole. The relief cut ostensibly forms a more flexible coupling between the soundboard and the sidewall of the instrument, which is represented to improve the tone of the instrument by allowing the soundboard to vibrate more freely. The relief cut in the soundboard is also represented to permit stretching and contraction of the wooden soundboard due to changes in atmospheric conditions.
According to the patent disclosure, the time-consuming process of tapering the soundboard surface is replaced with the localized relief cut. Referring to FIG. 1 of the patent, a dotted line 45 which follows the contour of the soundboard 30 is present inside of the perimeter of the soundboard 30. This dotted line 45 represents the general location of relief cuts 100, 110, 120, 130, 140, and 150, which are located on the soundboard 30. The cross-sectional area of the relief cut 100 may be varied along the soundboard 30, and the relief cut 100 may also have differing shapes and dimensions. The soundboard with relief cut disclosed by the '581 patent requires, however, that the soundboard return to its full thickness at the gluing surfaces of the soundboard and sides.
In view of the disadvantages outlined above, there exists a need for an acoustic musical instrument soundboard that does not require its own taper to achieve good tonal quality. There also exists a need for a wooden acoustic musical instrument soundboard that is robustly designed to be resistant to changes in atmospheric conditions such as humidity and temperature levels. Another need exists for a soundboard that, especially when combined with other components of a musical instrument, achieves tonal optimization.

Acoustic stringed instrument body with partial taper soundboard recurve


A roll for a pulp machine, paper machine, or paper finishing machine with a cylinder mantle of cast iron or steel, or any other equivalent metal, which bears the mechanical loads. On the roll mantle, fixed to the outer face of the mantle, there is a resilient polymer coating, and onto the polymer coating a coating is fixed which is by several orders thinner than the radial thickness of the polymer coating. This coating fixed onto the outer face of the polymer coating is a metal, ceramic, cermet or plastic coating.

The invention concerns a roll for a pulp machine, paper machine, or paper finishing machine, said roll comprising a roll mantle of cast iron or steel or any other, equivalent metal, which bears the mechanical loads, as well as a method for the manufacture of the roll and the use of such a roll.
Coated rolls are used in paper machines and paper finishing machines in highly varying applications. As examples of such applications should be mentioned press rolls, suction rolls, soft rolls of calenders and supercalenders, and the equivalent. In different applications and in different processes, different quality requirements are imposed on the roll coating. Usual quality factors of a coating are, among other things, hardness at a certain temperature, resistance to temperature, resistance to compression, chemical strength, smoothness of its face, resistance to mechanical damage, elasticity, surface energy, electrical conductivity, and resistance to ageing.
Thus, more specifically, what is required from paper machine rolls and mainly from roll coatings are surface properties such as hardness/ wear resistance, e.g., in the case of G-rolls and calender rolls, resilient surface, nip and oscillation properties, e.g., in the case of soft-faced press rolls, friction properties, e.g., in the case of paper guide rolls and central rolls, and resistance to corrosion, e.g., in the case of all rolls in the wet end.
The soft coatings on rolls are usually made of organic polymers or mixtures of these polymers which frequently also contain inorganic elements. The soft coatings on rolls are frequently composite constructions, which comprise layers made of different materials.
A problem, e.g., in the case of supercalenders is the poor resistance to heat of coatings made of natural fibres, whereby the high surface temperature of a metal-faced roll, which is advantageous in view of the calendering result, cannot be utilized to the full extent. An increased temperature also restricts an increasing of the compression pressure in calender nips. The roll face is readily damaged in operation. On the other hand, synthetic materials are highly expensive, and limiting factors in the choice of synthetic materials include resistance to heat, hardness, elasticity, and properties of surface energy.
Traditionally attempts have been made to modify the coating properties of polymer-coated rolls by inserting into the coating mixing various additives and fillers. By means of such mixing, attempts have been mostly made to modify/improve properties of the polymer such as cost, wear resistance, resistance to corrosion, thermal conductivity, stiffness, properties of detaching, friction, properties of hysteresis, etc. As one of the problems associated with the mixing it should be mentioned that, when a polymer material is mixed to modify some property, at the same time some other property important for the operation deteriorates. For example, there is a polymer material which operates very well in view of the operation of a press roll, which means that the nip width is good, there are no problems with respect to hysteresis heat, the running quality is good, the adhesion to the metal frame is good, and, moreover, it endures surface pressures and attenuates oscillations, but a residual problem is that the wear resistance is not sufficiently good. In traditional methods, to improve the wear resistance hard, finely divided particles which increase the wear resistance are mixed into the polymer. This mixing increases the wear resistance of the coating, but at the same time it deteriorates properties vital for the press roll, and, as a result, the nip width is reduced, the ability to attenuate oscillations is lowered, the adhesion to the metal frame becomes weaker, the running quality suffers, and in some cases also the resistance to corrosion is reduced. In the worst cases, the final result may be an unusable roll.
Generally speaking, in respect of the prior art regarding the technique of mixed coatings, the Applicant's FI Patent 72,073 is mentioned, wherein a press roll is described whose surface layer is composed of a mixture of a metal powder and an inorganic material. The function of the metal is to act as a binder agent and to increase the toughness of the roll coating, and the function of the inorganic material is to provide a wear-resistant surface of suitable surface energy, because the surface energy of the roll must be within certain limits in order that the detaching of the paper web from the face of the press roll should be controlled. The Applicant's FI Pat. Appl. No. 853544 is of a type similar to that mentioned above. As prior art, reference is also made to the Applicant's FI Pat. Appl. No. 882006, wherein the coating is composed of a powder which consists of carbide-rich powder and of matrix powder.
In the prior art, various multi-layer constructions of rolls and processes for their manufacture are also known. As an example should be mentioned the FI Patent No. 66,667 (Eduard Kusters), wherein, on the roll core, there are a number of rings made of steel in the axial direction, and onto the cylinder core an inner layer and an outer layer have been fixed, which are surrounded from the outside by said rings. A layer construction is also known from the FI Patent No. 55,457 (Beloit Corporation), wherein a combination roll is described, which comprises three concentric roll mantles made as separate casts, a metallurgical bond being provided between said roll mantles. Also, from the FI Pat. Appl. No. 880592 a roll is known which is provided with a multi-layer coating.
One polymer coating and a method for its manufacture are known from the FI Pat. Appl. No. 854748.


To dynamically map nodes for locality and balance, computer implemented methods, systems, and computer readable media, in an embodiment, may compute histograms for nodes in a first partition. Histograms may be computed for nodes in a second partition. The second partition may be selected as a candidate partition for a set of nodes in the first partition based on the histograms for the nodes in the first partition. The first partition may be selected as a candidate partition for a set of nodes in the second partition based on the histograms for the nodes in the second partition. At least a portion of the set of nodes in the first partition may be mapped to the second partition and at least a portion of the set of nodes in the second partition may be mapped to the first partition based on load balancing.

Social networking websites provide a dynamic environment in which members can connect to and communicate with other members. These websites may commonly provide online mechanisms allowing members to interact within their preexisting social networks, as well as create new social networks. Members may include any individual or entity, such as an organization or business. Among other attributes, social networking websites allow members to effectively and efficiently communicate relevant information to their social networks.
A member of a social network may highlight or share information, news stories, relationship activities, music, video, and any other content of interest to areas of the website dedicated to the member or otherwise made available for such content. Other members of the social network may access the shared content by browsing member profiles or performing dedicated searches. Upon access to and consideration of the content, the other members may react by taking one or more responsive actions, such as providing feedback or an opinion about the content. The ability of members to interact in this manner fosters communications among them and helps to realize the goals of social networking websites.
A social network may be modeled as a social graph. Node graphs, such as social graphs, may include an extremely large number of nodes and edges connecting the nodes. In the case of a social networking system, users are able to access and share vast amounts of information reflected in the node graph. The number of nodes, for example, may be in the hundreds of millions or even billions. The maintenance and provision of such vast amounts of data present many challenges.

Systems and methods for dynamic mapping for locality and balance


Methods and systems are provided for operating a high pressure injection pump to provide each of high fixed fuel pressure at a port injection fuel rail and high variable fuel pressure at a direct injection fuel rail. Port injection fuel rail pressure can be raised above a pressure provided with a lift pump via a fuel system configuration that includes various check valves, pressure relief valves, and a spill valve positioned between an inlet of the high pressure injection pump and the port injection fuel rail. High pressure port injection may be advantageously used to provide fuel at high pressure during conditions when fuel delivery via high pressure direct injection is limited.

Direct fuel injection (DI) systems provide some advantages over port fuel injection systems. For example, direct fuel injection systems may improve cylinder charge cooling so that engine cylinders may operate at higher compression ratios without incurring undesirable engine knock. However, direct fuel injectors may not be able to provide a desired amount of fuel to a cylinder at higher engine speeds and loads because the amount of time a cylinder stroke takes is shortened so that there may not be sufficient time to inject a desired amount of fuel. Consequently, the engine may develop less power than is desired at higher engine speeds and loads. In addition, direct injection systems may be more prone to particulate matter emissions.
In an effort to reduce the particulate matter emissions and fuel dilution in oil, very high pressure direct injection systems have been developed. For example, while nominal direct injection maximum pressures are in the range of 150 bar, the higher pressure DI systems may operate in the range of 250-800 bar.
One issue with such high pressure DI systems is that when the engine is configured with both direct fuel injection and port fuel injection (DI-PFI systems), the system is limited to operating the port fuel injection system at low pressure conditions. In other words, high pressure port fuel injection, such as higher than 5 bar, may not be possible without the inclusion of an additional dedicated pump. As such, while there may be conditions when high pressure port fuel injection is desirable, the addition of another pump for raising the pressure of the port injection system may add cost and complexity. Another issue with such high pressure DI systems is that the dynamic range of the injectors may be limited by the rail pressure. Specifically, when the rail pressure is very high and the engine has to operate at low loads, the direct injector pulse width may be very small. Under such small pulse width conditions, direct injector operation may be highly variable. In addition, at very low pulse widths, the direct injector may not even open. These conditions can result in large fueling errors.
In one example, the above issue may be at least partly addressed by a method for an engine, comprising: operating a high pressure fuel pump to deliver fuel at a variable pressure to a first fuel rail coupled to direct fuel injectors, and at a fixed pressure to a second fuel rail coupled to port fuel injectors, the fuel delivery controlled via a mechanical spill valve of the pump, wherein the second rail is coupled to an inlet while the first rail is coupled to an outlet of the pump. In this way, the specific configuration of the fuel rails relative to the high pressure fuel pump, as well the use of a mechanical spill valve and various additional check valves, enables a single high pressure fuel pump to be used to provide a substantially higher port fuel injection pressure.
As an example, a fuel system may be configured with a low pressure lift pump and a high pressure injection pump. The high pressure pump may be a piston pump. An output of the high pressure injection pump may be controlled mechanically, and not electronically, via the use of a magnetic solenoid valve (MSV). At least one check valve and one pressure relief valve (or over-pressure valve) may be coupled between the lift pump and the injection pump. A first fuel rail delivering fuel to direct fuel injectors may be coupled to an outlet of the injection pump via a check valve and a pressure relieve valve. Likewise, a second fuel rail delivering fuel to port fuel injectors may be coupled to an inlet of the injection pump, also via a check valve and a pressure relieve valve. An unenergized MSV enables a fixed pressure of the second fuel rail to be raised substantially higher than the fuel pressure provided by the lift pump. For example, the pressure of the second fuel rail delivering fuel to port injectors can be raised to the same level as the minimum pressure of the first fuel rail delivering fuel to direct injectors (such as at 15 bar). The pressure of the first fuel rail may be further raised and varied by adjusting the pump output via the MSV. Thus, based on engine operating conditions, fuel may be delivered at high pressure to an engine cylinder via port injection and/or via direct injection. Further, during conditions when fuel delivery via high pressure direct injection is limited, such as during cold-starts (and extreme cold-starts) or when engine exhaust emissions are particulate matter limited, direct injection may be disabled and fuel may be delivered via one or more high pressure port injections.
In this way, port fuel injection may be provided at fuel pressures that are higher than the default pressure provided by a lift pump. More specifically, a high pressure displacement pump can be advantageously used for providing variable high pressure to a direct injection fuel rail while also providing a fixed high pressure to a port injection fuel rail. By raising the port injection default pressure to be as high as the direct injection minimum pressure, various benefits of high pressure port injection can be achieved. For example, fuel can be port injected at high pressure without incurring particulate matter issues associated with direct injection. In addition, smaller amounts/volumes of fuel can be port injected more accurately when direct injection of the equivalent amount is limited by the pulse-width or dynamic range of the direct fuel injector. Overall, fuel injection efficiency is increased and fueling errors are reduced, improving engine performance.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

Methods and systems for fixed and variable pressure fuel injection


A storage apparatus (10) for converting a standard drawer (12) into a multiple level drawer having a stationary base tray (24) and a shiftable upper tray (26). The base tray (24) is secured to the front of the drawer (12) and includes laterally extending filler flanges (44, 46) on right and left sides of the base tray (24). The upper tray (26) is detachably secured to a support panel (54). Roller and track assemblies (30, 32) interconnect the support panel (54) of the upper tray (26) to the base tray (24). The upper tray (26) is shifted until it extends through an opening (76) formed in the rear wall (18) of the drawer (12). The roller and track assembly (30, 32) preferably includes channels (60) secured to the upstanding walls (34, 36) of the bottom tray (24) and bearing members (62) secured to the channels (60). According to the method of the present invention, the storage apparatus is retrofitted to a standard drawer which is modified by removing a cut-out from the rear wall of the drawer. The base tray (24) is secured to the modified drawer and the upper tray (26) is attached for horizontal shifting to the base tray (24). The method also includes molding the base tray (24) and upper tray (26).

Kitchen utensils, medical supplies, dental tools and other small articles are stored in special partitioned drawers which permit separation of small articles while stored in the drawer. In many instances, it is desirable to increase the number of compartments within a drawer.
Molded utensil trays having compartments for kitchen utensils or other small objects are conventionally placed loosely in the bottom of a drawer. In some instances, it is desirable to have even more compartments to increase the available number of compartmentalized storage sections in a drawer.
One approach to this problem is shown in a product catalog published by SieMatic Mobelwerke GmbH & Co. (SieMatic) at page 77, wherein specialized original equipment drawers having a slidable utensil tray are disclosed. The specialized drawer has a slidable tray which is built into the sides of the drawer. The sides of the drawer have milled slots extending from front to rear at an intermediate height on the inside wall of the drawer. The slidable tray has extensions on both sides which fit into the milled slot. The SieMatic drawer is well suited for drawers of new cabinet systems, but it is not well suited for retrofitting to existing drawers due to the difficulty of forming the guide slots in the sides of previously assembled drawers. In addition, assembly of the slidable tray to a standard drawer would be fairly complicated.
The milled slots in the sides of the drawers may create substantial friction which would resist easy movement of the tray slide. It is also not easily adapted for retrofit into different width drawers as would be essential to a simple and effective retrofit kit.
It is an object of the present invention to provide a multiple level compartmentalized storage tray which is suitable for retrofit to a wide range of drawer sizes.
Another object of the present invention is to provide a multiple level storage tray having a upper storage tray which is easily slidable in drawer guides between a closed position above a base tray slide and an open position wherein the upper tray slide is cantilevered through an opening in the back wall of the drawer.
An object of the present invention is to provide a multiple tiered drawer insert kit for retrofit in a standard drawer to increase the storage capacity of the drawer which is not difficult to install and does not require specialized tools for installation.
Another object of the present invention is to provide a two-tiered compartmentalized storage tray having an upper storage tray which is biased to the closed position as the drawer is opened.
These and other problems and disadvantages are overcome and the above objects are achieved by the present invention as will be more fully described below.

Method and apparatus for retrofitting a drawer with a multiple level storage tray


A prefabricated, self-contained and self-supporting container (10) for converting dry cargo vessels in whole or in part to bulk liquid products carriers and for rapidly transporting, storing and dispensing bulk liquid products at remote locations lacking storage and dispensing facilities. A loading rack (140) allows for rapid and convenient filling of tank trucks or tank cars from the container. A plurality of active or passive containers may be connected in series to create a large terminal facility or tank farm capable of storing and dispensing a large volume of a single product or smaller volumes of a plurality of compatible products. A method for loading and unloading said containers is provided by off-loading an empty container and filling it with liquid cargo from a loaded container. The newly empty container may then itself be off-loaded and filled from yet another full container. The containers can be used to make a prefabricated, self-supporting and self-contained bulk liquid products or bulk flowable dry products terminal or tank farm at a desired location even if the location is remote and lacks basic support services such as electricity.

Bulk liquids are traditionally transported in specialized tanker vessels. These ships are relatively few in number compared to dry cargo vessels and require specialized terminal facilities for discharging their cargo ashore for storage and further distribution. These bulk liquid terminals usually need a power source to pump the stored liquid out of the terminal.
Dry cargo vessels are generally configured to transport a plurality of containers of standardized sizes and shapes ("standardized cargo containers") which are described below.
The conversion of dry cargo vessels into liquid product carriers is desirable in order to increase the number of vessels able to carry bulk liquid products. Further, the use of multiple discrete liquid product containers to convert the dry cargo vessels is preferred in order to maximize the increased flexibility conversion offers in determining the portion of a vessels dry cargo capacity to convert into liquid cargo capacity.
In addition, many commonly transported and stored liquid products require certain safety features on their containers. Petroleum products, for example, require that pressures within a container be maintained within a certain range in order to prevent an explosion or an implosion. Also, an inert gas blanket must fill the ullage of the container in order to prevent an explosive gas mixture from developing. Oxygen-containing gases, such as air, must be excluded from any place in which petroleum fumes might gather in a dangerous quantity, therefore, a proper venting system is required. Fire-fighting or fire-prevention systems also may be needed.
Many locations have the ability to make liquid products from local raw materials, but currently lack a terminal facility or tank farm to store the manufactured liquid products pending the arrival of an appropriate carrier. Therefore, these locations export raw solid materials instead of manufactured liquid products, to their economic detriment.
Currently, a liquid products terminal facility or tank farm able to receive off-loaded bulk liquid cargo or to store bulk liquid cargo pending the arrival of a liquid products carrier must be constructed using traditional means encompassing much expense, pre-planning and a lengthy period of time.
The inventor is not aware of any container that can be used to convert all or part of a dry products carrier into a liquid products carrier and that can also be used as a transportable, prefabricated bulk liquid products terminal capable of rapidly creating a storage and dispensing facility for bulk liquid products even in remote and primitive areas or to be easily loaded and unloaded aboard a dry cargo vessel.
U.S. Pat. No. 4,746,034 to Ata et al. discloses a portable liquid container which can be stacked up to three units high. When stacked, the containers can be connected in a manner permitting the upper tanks to drain into the lowest tank. Liquid is discharged solely by gravity through a valve located underneath the container which is connected by a pipe to a hole located in the lowest point of a floor which has four sloping triangular portions whose apices converge at the lowest point.
U.S. Pat. No. 4,782,973 to Wiese discloses a storage tank having a double-walled bottom which permits the insulation of the tank bottom, and a flanged discharge valve suitable for the double-walled bottom configuration for gravity discharge of the liquid.
U.S. Pat. No. 2,328,080 to Hansen discloses a stationary storage tank located inside a housing designed to reduce condensation and with a hood or cowl located over the tank to facilitate the exit of fumes from the housing and to prevent moisture, dirt and other undesirable elements from entering the housing.
U.S. Pat. No. 3,814,290 to Gerhard discloses the use of a trough in the interior of a tank to promote easy draining and cleaning of a liquid cargo tank that has a plurality of compartments.
The above containers are not specifically designed to serve as a dual purpose transportation container and terminal for storing and dispensing bulk liquid products, including flammable or other hazardous liquid products. None provide access for a person to enter the container, none has an active means of pumping the stored liquid out of the container, none has an active fire protection or control means attached, nor does any have a means for providing and maintaining an inert gas cover when necessary or required, or for venting the container other than directly into the atmosphere at the tank top.
U.S. Pat. No. 3,781,139 to Lohse discloses a detachable power unit comprising an internal combustion engine and an energy transducer for attachment to freight containers.
U.S. Pat. No. 3,386,605 to Lafont discloses a large plastic bag able to permit standard modular size demountable cargo containers to carry bulk liquid cargo instead of packaged cargo.
U.S. Pat. No. 4,143,588 to Exler discloses a ventilation system comprising walls and channels inside a "deepfreeze" container to maintain an even temperature and humidity throughout the interior of the container transporting standard dry cargo at a controlled temperature.
U.S. Pat. No. 2,954,003 to Farrell et al. discloses a liquid products tank capable of transporting liquified gas at low temperatures in the hold of a ship using cables, keys and keyways to secure the tank so that changes in the size of the tank due to temperature extremes will not affect the ability of the ship to transport the tank. The tank is suspended within a thermal barrier so that it may carry cryogenic cargo without significant warming and without harmful contact with the ship's structure.
U.S. Pat. No. 3,067,713 to Meesen discloses a freighter for low-temperature liquified gas comprising tanks of light alloy metal mounted in a series of corrugated and beveled guides within the insulated hold of a ship to allow movement of the tank in all directions due to changes in tank dimensions brought about by temperature extremes of the liquified gas cargo to be carried in the tanks.
U.S. Pat. No. 3,115,984 to Henry et at. also discloses a tanker for carrying low-temperature liquified gas comprising at least one multiple compartment tank in an insulated hold specially constructed for use aboard the tanker.
U.S. Pat. No. 4,107,803 to Sylverest discloses a self-contained and self-powered sea terminal which floats on the surface of the sea designed to store and discharge liquids through pumps located onboard the terminal.
None of these references discloses the degree of transportability and features necessary to allow a container for flammable, explosive, hazardous, or non-hazardous liquid products both to be carried aboard a dry cargo vessel (thereby permitting its use as a liquid products carrier), and to be used as a prefabricated, transportable liquid products terminal facility for use in areas lacking needed terminal facilities. These features in a container allow the shipment of liquid products aboard a greater number of types of vessels and to a greater number of places.
It is therefore an object of this invention to provide a liquid products container that can be transported to a desired location lacking a liquid products terminal or tank farm (even to a remote location lacking an available electrical supply), and can serve as a prefabricated, self-contained terminal immediately able to store and dispense flammable, hazardous or explosive liquid cargo, as well as non-hazardous liquid cargo and some types of dry bulk cargo, such as cement.
It is a further object of this invention to provide a multiple-container liquid products terminal facility at a remote location without undue expense or unnecessary duplication of equipment by using a single active container in association with one or more passive containers, or by using one or more passive containers in association with some other external pump source or in a location and manner permitting gravity discharge of the containers' contents.
It is a still further object of this invention to provide a liquid products terminal having a loading arm ("rack") for rapid and easy transfer of liquid from the terminal to trucks or tank cars.
It is a still further object of this invention to provide a storage container for liquid products capable dispensing its liquid product immediately upon its arrival and filling at a desired location, even in a remote area.
It is a still further object of this invention to provide a liquid products container that can carry many types of liquid cargo and be easily loaded onto and carried aboard a dry cargo vessel, thereby converting said vessel in whole or in part to a liquid products carrier and increasing the amount and type of transportation available to carry bulk liquid cargo.
It is a still further object of this invention to provide an economically efficient means for remote locations to store and dispense various amounts of bulk liquid cargo under necessary storage conditions pending the arrival of an appropriate carrier.
It is a still further object of this invention to provide a method for increasing the number of vessels able to serve as an appropriate carrier for bulk liquid products or bulk flowable dry products.

Instant Terminalling and Ship Conversion, Inc.


A system for applying maximum driving efficiency point of load includes: a motor for driving a load; an inverter for controlling the speed and the voltage of the motor; a sensor unit for measuring the magnetic flux maintaining current and the torque current of the motor; and a control unit determining the speed of the inverter and using the proportional value of the magnetic flux maintaining current and the torque current measured within a range in which the total current does not increase when the motor is driven at the determined speed. The motor inverter control system can control both motor speed and voltage to select the lowest frequency within the permissible range and at the same time control the voltage at the water head to maximize power, thereby reducing power consumption to a minimum.

Generally, in order to drive the air-conditioning fan or the pump circulating the water, the torque of the driving motor has to be increased in proportion to the square of the speed. In this way, when the power supply voltage is directly connected to the motor driving the load of the quadratic torque type, energy waste is increased. In other words, if a power frequency of 60 Hz is used as a reference of the rotation speed and an induction motor having 4 poles is taken as an example, the reference speed becomes 1800 rpm, and the speed is operated regardless of the load condition. Therefore, it has been causing unnecessary energy consumption under partial load conditions. This problem can be solved by applying an inverter that controls the speed according to the load.
The load and the energy saving principle are explained more specifically.
As shown in FIG. 1, a load, for example, quadratic torque load, is a load of a centrifugal pump and a centrifugal fan, and is characterized in that electric power is consumed in proportion to the three squared of speed due to friction and inertia. Therefore, reducing the speed of the motor reduces power consumption further, which can significantly reduce energy.
To explain further, suppose that the pump is operated at a speed of 1800 rpm for one hour. At this time, it is assumed that the consumed power or electric power charge is 100%. Then reduce the pump by 50% at a speed of 900 rpm, and instead increase the operating time by 2 times to 2 hours. Then, the actual amount of flow pumped by the pump is the same, but its power usage or electricity charge is only 14% instead of 100%. In other words, by reducing the speed by 50%, the power consumption can be saved by as much as 86%.
If this pump is 37 kW, if we assume that 37 kW will be operated one hour a day for one year, that electricity fee will be charged around 1195$. However, to operate one hour a day for 4 hours with different speeds, instead of reducing the speed, its power is estimated to be around 19$. Also, if you run the pump slowly in 6 hours, the power is charged by 48$, but you can supply an amount like 1,194$ electricity before.
As described above, because the power is consumed in proportion to the three squared power of the speed, the power reduction can be dramatically reduced if the speed is reduced. The power consumption proportional to the three squared power is called affinity law #3.Therefore, energy can be saved by controlling the motor by using the inverter.
Hereinafter, the control operation according to the load size of the conventional inverter technology will be described in detail.
First, the characteristics of a motor, that is, an induction motor will be described.
The speed N (r/min) of the induction motor is expressed by the following formula.
                    N        =                                            120              ×              f                        P                                          (                          1              -              S                        )                                              [                  formula                                                              1                ]
Where N is the speed of the induction motor (or motor), f is the frequency, P is the number of motor poles, and S is the slip.
According to affinity law #1, the flow rate Q is proportional to the change in the number of revolutions (or the speed of the induction motor) (N). Therefore, the faster the speed of the induction motor, the more the flow rate supplied by the motor increases proportionally.
In addition, there is the following relationship for the voltage V of the induction motor, the frequency f and the magnetic flux (torque).
                    Φ        ∝                  V          f                                    [                  formula                                                              2                ]
Where Φ is the magnetic flux, V is the voltage, and f is the frequency.
At this time, the magnetic flux (Φ) or torque (τ) of the induction motor should be controlled by the size of the load, that is, the size (or height) of the head H. That is, It is necessary to control the voltage applied to the motor to the minimum magnitude that the maintaining and torque flux drive the load size.
Since the inverter can arbitrarily control the frequency f and the voltage V, the induction motor can be operated at a variable speed.
As an example of pumping, the flow quantities and heads at the load side correspond to the frequency f and the voltage V at the driver (inverter and induction motor) side, respectively. That is, by the inverter, how fast and how much power will be pumped up. That is, the variable that determines how fast the pump will pumped up is the frequency f, and the water head that determines how high the pump is raised determines the voltage V at the inverter side. Specifically, when pumping up the water, the element of "how much flow, how fast will you pumped up the water", the voltage factor is determined by the location of the reservoir tank, such as 5, 10, or 60 stories high. The control element of the pump is "how fast" and "how high" it is to be raised, the former corresponds to the flow Quantity, and the latter corresponds to the head. The higher the water head, the higher the water pressure, so the bigger the torque is required in the pump to meet the water pressure, so the "head/pressure/torque" has the same meaning.
So, in order to reduce the power to the maximum, the voltage corresponding to the water head must be controlled, and the power can be reduced to the maximum by selecting the lowest frequency. Conversely, reducing power to the maximum level results in the highest efficiency.
However, according to the related technology, when the motor for the load is controlled by the inverter, mainly the speed of the motor is controlled[Patent Literatures 1 and 2].
That is, the inverter of the related technology is used to determine the number of revolutions of how fast the motor is to be rotated, and the inverter determines the number of revolutions of the motor. Then, the motor manufacturer provides the water head and flow rate curve of the corresponding motor. This water head and flow curve, that is, the H-Q curve (water head-flow curve) are made with the curve required for inverter control using affinity's first law and second law, and accordingly H-N curve (water head-flow curve) to control the inverter.
In other words, as shown in FIG. 2, the flow rate Q can be obtained by applying H-N curve to the motor (or inverter) using the H-N curve after applying the affinity law #1, #2 of the following formulas 3 and 4.Q∝N   [formula 3]H∝N2(T∝N2)   [formula 4]
Where Q is the flow rate (or air flow rate), N is the velocity, τ is the torque, and H is the head (or pressure, head, static pressure).
As a result, the current technology controls the inverter to match the H-N curve. Therefore, if the head H is high, the speed N must be controlled to be high. For example, suppose a situation in which an inverter is required to operate at 1800 rpm. At this time, suppose that the necessary head (H) is 120 Pa. It is also assumed that the flow rate required by the current system is 1200 rpm in order to reduce power by the affinity low. That is, the speed of the motor can be reduced from 1800 rpm to 1200 rpm. However, when I tried to rotate the motor speed to 1200 rpm, when I looked at 1200 rpm, the head (H) was only 50 Pa. Therefore, since the required head is 120 Pa, it can not be pumped up when operated at 1200 rpm. However, according to the H-N curve, when the head is 120 Pa, the motor speed must be 1600 rpm.
Therefore, the motor speed can be reduced from 1800 rpm to 1200 rpm for power reduction, but it can be reduced to only 1600 rpm due to the H-N curve limitation. As described above, power consumption is proportional to the three squared of the speed by the affinity low. According to the related technology, power can be saved only by the third power of 200 rpm at 1800 rpm and 1600 rpm. However, since the motor speed can be reduced to 1200 rpm, the power corresponding to the third power of 400 rpm, which is the difference between 1600 and 1200, is wasted.
When the motor is rated at an efficiency in rated operation, the motor becomes saturated by increasing the voltage with respect to the rated frequency in EMF equation V=4.44fnφ(V: voltage, n=number of turns, φ=magnetic flux). Therefore, the frequency control of inverter controls the ratio of rated voltage/rated frequency constantly.
As mentioned earlier, in order to raise the water, it is necessary to control both the flow rate and the head of water. However, the head of water does not fit properly when the control is performed only by the flow rate. Thus, according to the related technology the two control elements, namely, the flow rate and the head of water, must be satisfied, so that the water is quickly pumped up and the flow rate is greatly increased to match the head of water. As a result, 400 rpm is consumed more and power corresponding to three squares of 400 rpm is wasted. Calculating this, it is estimated that 44% of the power is wasted. Therefore, it can be seen that the conventional inverter is not able to control the voltage, so that the power is wasted at a large amount in the square-root reduction load. Since the conventional inverter can not control the voltage, it is necessary to raise the water at a speed of 1200 rpm. However, the water is pumped at a speed of 1600 rpm, which causes a large amount of power waste due to the affinity law.
Further, techniques using an inverter for controlling the torque have been proposed (Patent Documents 3 and 4), and vector control inverters for torque control have been commercialized. Therefore, it can be applied to the load by using an inverter that controls the torque instead of the voltage. However, in the case of an inverter using a torque, that is, a vector-controlled inverter, the inverter is sold at a price about 2.5 times as high as that of an inverter that controls only a speed. In addition, even a vector-type inverter capable of controlling torque is not designed to achieve maximum efficiency control in a load. Even if it is designed with maximum efficiency control, it is impossible to control at the maximum efficiency practically because all the necessary conditions in the load are not known by the inverter.
In other words, the vector control (Vector control, Field oriented control) method separates and controls the torque component and the flux component, and is widely used for high performance variable speed control with excellent control performance. However, since the number of controllers is large and complex and the amount of information to be detected is large, the manufacturing cost is high and it is disadvantageous in terms of economy.
In summary, in the related technology, when the voltage depending on the flow rate is larger than the required water head, it can not be reduced to the voltage suited to the water head, so that it is impossible to reduce the power consumption, so there is a problem that the maximum efficiency operation can not be performed.

System for applying maximum driving efficiency point of load


A method and apparatus for the early detection and relief of a closed, pressurized gas charged system, such as an ammonia refrigeration system, wherein a central control system measures and assimilates system and ambient conditions, and responds to alleviate system pressures in excess of design parameters, and, further, combusts system gasses so relieved, breaking such gasses into nontoxic byproducts of combustion.

The present invention relates generally to the prevention of destructive conditions in gas driven systems, where the gaseous medium is toxic, or explosive, or both. More particularly, the invention relates to means for detecting the onset of system conditions which are potentially dangerous to the integrity of a gaseous system, and relieves those conditions before a rupture or other disaster to the system results.
There are several gas driven systems in both commercial and consumer use. Cooling systems, and particularly commercial refrigeration systems, are predominantly pressurized gas driven, and ammonia is the current coolant of choice for such systems. However, free ammonia is considered toxic, and when used in a refrigeration system where expansion and compression of the gaseous medium is constantly taking place, the opportunity for breach of the system, with the concurrent escape of toxic gasses, is great.
By way of example, one need only consider the stress placed on such a system when ambient temperatures are driven into high ranges, such as by explosion or fire. Pressures in the system are quickly driven upwardly, and potentially beyond the design parameters of the system itself. Depending on the gaseous medium, a rupture of the system could have calamitous results. Similar problems can result from seismic disturbances. It is such problems that the present .invention attempts to address.

Apparatus for the early detection and relief of unsafe conditions in a gaseous system


The disclosure relates to a current stimulator, which comprises a high voltage output module, a voltage control module and a charge pump module. The high voltage output module includes a plurality of stacked transistors, and receives an input control signal able to turn on/off the current stimulator and a first voltage. A second voltage is generated by adding the voltages output by all the transistors to the first voltage and then output to the voltage control module. The voltage control module outputs a voltage control signal able to stabilize the stimulus current for the load according to the second voltage and the load impedance variation. The charge pump regulates the first voltage according to the voltage control signal, and outputs the regulated first voltage to the high voltage output module. Thereby, the current stimulator can adaptively stabilize the stimulus current, responding to load impedance variation.

1. Field of the Invention
The present invention relates to a current stimulator, particularly to a load-adaptive current stimulator fabricated in a low voltage IC process and able to output a stimulus voltage much higher than the supply voltage.
2. Description of the Related Art
Wafer foundries are flourishing in Taiwan. Without having to go far, IC industry of Taiwan is supported by the neighboring world-class wafer foundries and is growing fast with high technical burst power. IC industry of Taiwan has successfully developed various IC products. Further, the related organizations and manufacturers also integrate IC technology with biological technology to improve the medical environment and promote health of people.
Electric stimulus is an emerging medical technology and regarded as an alternative route to cure some illnesses thought incurable before, wherein current is used to stimulate a region to restore the function thereof. Advance in IC miniaturization makes it feasible to incorporate an intelligent bionic system in a single chip. Although different types of circuits can be integrated in a system-on-chip (SOC), there is still a problem for SOC current stimulators: current stimulators have to operate in a high voltage environment. When an IC fabricated in low voltage IC process operates in a high voltage environment, the voltage may be greater than the withstand voltage of the elements. In such a case, IC is likely to have problems of electric overstress, low gate-oxide reliability, hot-carrier degradation, and leakage current.
Besides, the load impedance varies with the region where the current stimulator is attached. Even in the case that the current stimulator is applied to the same region, the load impedance may vary with the materials of the electrodes and the duration of applying current stimulation. When the load impedance does not match, the stimulus current is no more effectively output.
Accordingly, the present invention proposes a current stimulator to overcome the abovementioned problems.