A row unit comprises a row unit gearbox with two shearing edges and two stalk rolls with corresponding shearing edges, wherein the stalk roll shearing edges shear against the gearbox shearing edges when the stalk rolls rotate during normal operation of the row unit, thereby chopping material that might otherwise be wrapped around the row unit gearbox and be jammed between the stalk rolls and the gearbox.

In one common configuration, known in the prior art, corn heads comprise a laterally extending frame to which many row units are attached. The frame is configured to be supported on the front of an agricultural combine. Each row unit is configured to engage an individual row of crop plants, cutting the crop plant from the ground, and stripping the crop from the corn stalk. In one common row unit configuration, the row unit grasps the cornstalk, pulls it downward, and pulls the ears of corn off the stalk. These ears of corn are then provided to the threshing, separating, and cleaning portions of the agricultural combine to remove the individual kernels of corn. These kernels of corn are saved in a grain tank in the harvester.
Row units for corn heads typically have two forwardly extending rolls called "stalk rolls" that are disposed adjacent to each other. The stalk rolls are driven in rotation such that corn stalks trapped between them are pulled downward and ejected into the dirt below the corn head while the ears of corn are stripped off the stalk.
One problem with the row units for corn heads is their susceptibility to being jammed with shreds of plant matter, corn kernels, dirt, grass, or other materials on the ground. The row units skid along the ground, permitting all manner of contaminants to be introduced into the row unit.
A typical stalk roll may rotate at 1000 rpm as it travels along the ground only a few inches away from the dirt. Grass, weeds, broken corn stalks or other material may become jammed between the spinning stalk roll and the row unit gearbox on which it is mounted.
One solution to this problem has been to locate the stalk roll very closely to the gearbox itself providing a very small gap therebetween. Nonetheless, long fibrous plant material can become wrapped around the base of the stalk roll and wedged into this gap.
What is needed, therefore, is a row unit with an improved row unit gear box and stalk roll that reduced the likelihood of contamination. It is an object of this invention to provide such a row unit and stalk rolls.


Method and apparatus for detecting icing, particularly on airfoils such as helicopter rotor blades, by detecting warming caused by latent heat released as water freezes. The sensors may be multiple or single, contact or remote.

The present invention relates to the detection of ice accretion on the surface of an object which, during use, is subjected to atmospheric conditions in which an ice layer may form.
The reliable detection of ice accretion is important in several applications. One application of particular significance is in the all-weather operation of aircraft. During such operation, ice accretion on critical flight components must be detected with sufficient sensitivity that an operator can receive a "Caution and Warning" alert before a dangerously thick ice layer can form.
The above considerations come into play even more forcefully for moving-wing aircraft such as helicopters. Helicopter exposure to icing conditions has increased over the past decade because of the increase in routine instrument flight operations. Helicopter rotor icing can present a significant hazard due to increased torque requirements, aerodynamic performance degradation, control problems, and severe vibrations resulting from uneven ice shedding.
Because rotating components often experience icing conditions that are significantly different from those experienced by the fuselage, visual evidence of ice accretion on non-rotating structures is not adequate for Caution and Warning applications. Moreover, indirect indications of icing, such as torque rise or vibration increase, typically emerge only after a hazardous condition exists. On the other hand, the direct measurement of ice accretion on the rotating components would provide the earliest detection and most accurate measurement of a potential icing hazard.
Ice detection is also important in the management of ice protection systems. A common type of ice protection system is the electrothermal de-icer, which requires so much electrical power that airfoils are typically de-iced in segments. Without effective ice detection, it is necessary to overheat and continually cycle the electrothermal de-icing system to assure adequate ice protection. If an effective ice detector were available, electrothermal de-icers could be operated more efficiently and effectively.
The ice detectors most commonly employed for aviation applications are the direct-contact-type devices. In the typical direct-contact detector, a probe or surface-mounted transducer senses the presence of ice through a variety of physical mechanisms, such as by measuring resonant frequency shifting, optical blocking, heat capacity, electrical capacity or ultrasonic thickness. Direct-contact detectors are described in A. Heinrich et al., "Aircraft Icing Handbook--Vol. I", U.S. Dept. of Transportation Publication No. DOT/FAA/CT - 88/8-1 (March 1988).
Contact-type ice detectors have not been successfully used for direct measurement of rotor ice accretion due to the severe difficulties encountered in instrumenting a rotor. These difficulties include mounting restrictions imposed by structural limitations of the rotor blade, transmission of information between the rotating and non-rotating frames, acceleration limitations of the sensors, and erosion problems. As a result, a contact-type ice detector is typically mounted on the fuselage and the rotor's icing condition is inferred from the fuselage's condition. Such indirect ice detection has had only limited success because of the complex dependence of the icing process on the temperature, liquid water content, and velocity, all of which vary significantly between the fuselage and the rotor, as well as along and across each rotor blade.
Direct ice detection via remote sensing offers significant advantages for monitoring rotating blades. If ice accretion can be remotely detected by sensors mounted in the fuselage, then a direct measurement of rotor ice accretion can be accomplished without the difficulties identified above. Several techniques, including high-speed video and active microwave systems, have been investigated for remote ice detection.

Method of and apparatus for detection of ice accretion


Aspects of the invention include isolated anti-PD-L1 antibodies, as well as compositions containing such antibodies, and methods of using the same in the treatment of diseases or conditions that are mediated by PD-L1 signaling.

Programmed cell death protein 1 (PD-1) is a cell surface receptor belonging to the immunoglobulin superfamily, which includes cell surface and soluble proteins that are involved with recognition, binding, and adhesion processes of cells. The initial members of this family were discovered due to their functional effect on augmenting T-cell proliferation following the addition of monoclonal antibodies (Hutloff et al. (1999) Nature 397:263-266; Hansen et al. (1980) Immunogenics 10:247-260). Two cell surface glycoprotein ligands for PD-1, referred to as PD-L1 and PD-L2, have been identified, and have been shown to downregulate T-cell activation and cytokine secretion upon binding to PD-1 (Freeman et al. (2000) J Exp Med 192:1027-34; Latchman et al. (2001) Nat Immunol 2:261-8; Carter et al. (2002) Eur J Immunol 32:634-43; Ohigashi et al. (2005) Clin Cancer Res 11:2947-53). Both PD-L1 and PD-L2 are B7 homologs that bind to PD-1, but do not bind to other CD28 family members (Blank et al. (2004). Expression of PD-L1 on the cell surface has also been shown to be upregulated through IFN-γ stimulation.
PD-L1 expression has been found in several murine and human cancers, including human lung, ovarian and colon carcinoma, as well as various myelomas (Iwai et al. (2002) PNAS 99:12293-7; Ohigashi et al. (2005) Clin Cancer Res 11:2947-53). PD-L1 has also been suggested to play a role in tumor immunity by increasing apoptosis of antigen-specific T-cell clones (Dong et al. (2002) Nat Med 8:793-800). As such, targeting of the interaction between PD-1 and PD-L1 is an area of particular interest for therapeutic intervention. There is a need for therapeutic compositions, such as anti-PD-L1 antibodies, directed against targets in this pathway.


A route setting apparatus having a processor and a memory which stores an instruction to cause the processor to generate a layer label in which a first signal type for transmission of a main signal is described on a layer-by-layer basis, to store, on a layer-by-layer basis, a score correspondingly associated with one or more of second signal types, and to generate data based on the score correspondingly associated for one of the second signal types that matches the first signal type in the layer label. The instruction causes the processor to determine an optimal route based on the generated data which includes data received from another apparatus included in a route for the transmission of the main signal, and transmit and receive the layer label and the generated data.

When an apparatus has received a frame using a different protocol, the apparatus converts the frame, and transfers the converted frame using tunneling. An apparatus that has received such a frame refers to information stored in the header portion of the frame, and determines whether or not to terminate or transfer the frame.
A related technique is described in Japanese Laid-open Patent Publication No. 2001-144778.

Route setting apparatus, route setting method, and network system


A silicon wafer wherein stacking fault (SF) nuclei are distributed throughout the entire in-plane direction, and the density of the stacking fault nuclei is set to a range of between 0.5×108 cm−3 and 1×1011 cm−3.

1. Field of the Invention
The present invention is related to silicon wafers and their manufacturing method, in particular, to technology suited to the manufacture of silicon wafers having a superior intrinsic gettering (IG) effect. Priority is claimed on Japanese Patent Application No. 2002-336690, the content of which is incorporated herein by reference.
2. Description of Related Art
Silicon wafers manufactured by processing a silicon single-crystal grown by pulling with the Czochralski (CZ) method contain many oxygen impurities. These oxygen impurities form oxygen deposits (referred to as Bulk Micro Defects: BMD) which give rise to dislocation and defects and the like. When these oxygen deposits are on the surface on which devices are formed, they cause increased leakage current and reduced oxide film withstand voltage and the like, having significant effects on the characteristics of the semiconductor device.
Conventionally, therefore a method as hereunder, wherein a DZ layer (Denuded Zone, i.e. a defect-free layer) is formed uniformly has been employed (see pamphlet International Unexamined Patent Application No. 98/38675). That is, the surface of the silicon wafer is rapidly heated to a temperature of 1250° C. or higher and quenched (Rapid Thermal Annealing: RTA) over a short period of time, in a prescribed atmosphere gas to form a high concentration of atomic vacancies (hereafter referred to as 'vacancies') within the interior of the silicon wafer. Furthermore, quenching the silicon wafer freezes the atomic vacancies. It is then heat treated at, for example, a temperature of 800° C. for four hours, after which it is then immediately heated to 1000° C. for 16 hours, to disperse the vacancies on the surface of the wafer to the exterior.
Moreover, conducting heat treatment at a temperature below the aforementioned temperature following formation of the DZ layer, forms and stabilizes oxygen deposits in the interior of the silicon wafer, forming a defect layer, and thus a process wherein a BMD layer having a gettering effect is formed is also adopted. Furthermore, other published documents include, for example, Japanese Unexamined Patent Application First Publication No. 2001-156074.
However, the following problems relating to the aforementioned heat treatment technology remain unresolved.
That is, a strong requirement exists for silicon wafers with a higher gettering capacity. However, raising the gettering capacity presents difficulties due to an increase in BMD size to between 50 nm and 200 nm.

Silicon wafer and manufacturing method thereof


A cutting element includes a body having two planes, each of the two planes defining a plurality of edges, and a support extending from a first of the two planes. The support and the body are configured such that when at least one of the plurality of edges and the support are in contact with the planar surface, edges of the plurality of edges on a second of the two planes form cutting edges and the second of the two planes forms an acute angle with the planar surface. The second of the two planes of the cutting element has a recess formed therein sized and positioned to be receptive to a support of a second cutting element similar to the cutting element when the first of the two planes of the second cutting element is butted against the second of the two planes of the cutting element.

Cutting tools, such as mills used in downhole applications, for example, can be made with a plurality of cutting elements that are adhered to a surface of a tool. The cutting elements can be randomly shaped particles made by fracturing larger pieces. Alternately, cutting elements can be precisely formed into repeatable shapes using processes such as machining and molding, for example. Regardless of the process employed to make the individual cutting elements the elements are typically adhered to the mill with random orientations. These random orientations create disparities in maximum heights relative to a surface of the mill. Furthermore, angles of cutting surfaces relative to the target material are randomized and consequently few are near preferred angles that facilitate efficient cutting. In addition to uniformity, greater tool life than can be achieved with a single layer of cutting elements is often desired. When even precisely formed elements with advantageous angles with respect to the target are stacked in multiple layers, the second layer typically has random orientation. A precisely formed element capable of being stacked in a controlled advantageous orientation would be well received in the industry.

This patent is subject to a terminal disclaimer.

Cutting element, tool and method of cutting within a borehole


A method for clocking a physical layer (“PHY”) and a controller of a computing device, comprises the steps of: generating a reference clock signal; synchronizing a plurality of clock signals as a function of the reference clock signal; and clocking the controller and the PHY using the plurality of synchronized clock signals.

A physical layer of a computing device ("PHY") is used for communicating between integrated circuits and external devices, such as other integrated circuits, typically through a data bus or a set of signal wires. The physical layer is typically configured to implement a desired communication protocol or specification that has been established for the particular application.
FIG. 1a illustrates a diagram of a physical layer of the prior art for communicating between a memory controller and an external memory device. A standard double data rate ("DDR") PHY 12 interacts with an on-chip memory controller 10 and an off-chip dynamic random-access memory ("DRAM") 22. The PHY 12 comprises a DDR physical layer interface ("DFI") 14, first-in-first-out ("FIFO") buffers 16, and address and data macros 18 for transmitting data between the FIFO buffers 16 and the DRAM 22. The memory controller 10 and the PHY 12 represent two primary design elements in DDR memory systems, which are used in virtually all electronic system designs, from cellphones and set-top boxes, to computers and network routers.
The DFI specification defines an interface protocol between the memory controller 10 and the PHY 12, with a goal of reducing integration costs while enabling performance and data throughput efficiency. The DFI protocol defines the signals, timing, and functionality required for efficient communication across the PHY, which is known by a person having ordinary skill in the art and can be found at the following webpage http://www.ddr-phy.org. The DFI specification also allows the memory controller 10 to be operated at a same frequency as DRAM 12, or at half (or other fraction) of the frequency of the DRAM 12.
FIG. 1b illustrates a graph of clock signals for a physical layer interface of the prior art. A CLK_CTL clock signal is inputted to the memory controller 10 from the clock generator 20 for clocking the memory controller 10. A CLK_MEM clock signal is inputted to the address and data macros 18 of the PHY 12 for clocking the address and data macros 18 to receive data from and/or transmit data to the DRAM 22. The CLK_CTL clock signal and the CLK_MEM clock signal are plotted side-by-side along a time axis. The CLK_MEM clock signal can have twice (or another multiple of) the frequency of the CLK_CTL clock signal. Also, the CLK_MEM clock signal and the CLK_CTL clock signal are asynchronous signals. Thus, there is uncertainty as to alignment of the clock signals. Since the frequencies of the CLK_CTL signal and CLK_MEM are different, the FIFO buffers 16 are needed to buffer any data to account for this asynchronous.
The depths of logic in the PHY 12 and in the memory controller 10 are different, and, moreover, the logic may be operating at integral multiple frequencies, which prove to be challenging during integration. The width of the PHY 12 makes it even more difficult to align the clock signals, e.g., the CLK_CTL, CLK_MEM, and the CLK_DFI signal, for the respective logic and components.
Traditionally, the FIFO buffers 16 are employed to store data between the memory controller 10 and the DRAM 22 in the PHY 12. The memory controller 10 writes data according to the CLK_CTL signal edge. The PHY 12 can then read/write the data according to the timing of the CLK_MEM signal. Based on the type of command, the PHY 12 can read data from the DRAM 22 or write data to the DRAM 22. A clock generator 20 generates the clock signals CLK_CTL, CLK_MEM, and CLK_DFI according to the operating frequencies of the memory controller 10, the DRAM 12, and according to the DFI specification.
If a write command is given, the PHY 12 reads the data based upon the CLK_MEM signal, and routes the appropriate command and data. If a read memory command is given, the PHY 12 reads the data based on the CLK_MEM signal and sends the appropriate command and data. The PHY 12 also can read the data, sending an appropriate command, and wait for the data from the DRAM 22. Once the data is available, the PHY 12 writes the data to the FIFO buffers 16, and informs the availability of data to the memory controller 10.
There must be a significant number of FIFO buffers 16 in the PHY 12 to provide reliable operation due to the frequency ratio of the CLK_CTL and the CLK_MEM signals, and due to uncertainties between and among clock distributions for the various components of the PHY 12. Additionally, the minimum latency for reliable operation needs at least three additional cycles of CLK_MEM due to a clock domain crossing, which will increase the overall latency of the system and also increase the needed chip area. The depth of the FIFO buffers 16 also depends on the frequency ratio and the skew between the clock signals from the clock generator 20.
Therefore, there exists a need to provide new methods and systems for providing a PHY that can account for any frequency ratio, decrease latency, and reduce the amount of chip area used for the PHY. In particular, there exists a need to provide new methods and systems for a PHY that do not need FIFO buffers between a memory controller and an external memory.
Additionally, the PHY must evenly distribute a reset signal and the clock signals throughout the PHY and the memory controller. In order to keep the data in correct order, the reset signal must be simultaneously distributed throughout the memory controller and the PHY.
FIG. 7 illustrates a diagram of a distribution network of the prior art for distributing clock and reset signals. Typically, a DDR data macro can be 72 bits wide in depth, and 10 mm long in length. Due to its relatively extensive depth and length, clock distribution in the DDR macro is challenging in itself, and further difficult when trying to synchronize the signals for the DDR macro. Prior art uses two independent balanced distribution networks, one for a clock signal I_CLK and the other for a reset signal I_RESET.
The clock signal I_CLK is distributed to divider and counter blocks 30 via a first distribution network 28. Simultaneously, a clock signal I_RESET is also distributed to divider and counter blocks 30 via a second distribution network 26 to mirror the timing of when the I_RESET signal is received by each of the divider and counter blocks 30. Unfortunately, the second distribution network 26 consumes a great amount of chip area and consumes a great amount of power.
Therefore, there exists a need to provide new methods and systems for distributing clock and reset signals to reduce the amount of chip area used and to reduce power consumption for distributing the clock and reset signals.

Methods and systems for clocking a physical layer interface


The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is --H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

1. The Field of the Invention
The present invention is related to methods and compounds for use in the field of determining renal function by means of scintigraphic urography. More particularly, the present invention is directed to renal system imaging in which technetium-99m radiolabeled chelates are used.
2. The Prior Art
Regulation of the content and quantity of body fluids is critical to the basic physiology of bodily functions. For instance, it is necessary for the body to regulate such fluid-related variables as total body fluid volume, constituents of extracellular body fluids, the acid-base balance in body fluids, and various factors that affect interchange of extracellular and intracellular fluids (most notably, factors that affect the osmotic relationship between such fluids).
The kidneys are the primary body organs that are responsible for regulation of the composition of body fluids. Thus, the kidneys maintain body fluids within a physiologically acceptable range by excreting most of the end products of metabolism and by regulating the concentrations of desirable body fluid constituents.
The human body contains two kidneys that function to form urine containing fluid constituents that are to be eliminated through the bladder. The basic biological unit that performs the work of the kidney is the "nephron." Each kidney is comprised of some one million nephrons, with each nephron being capable of regulating body fluid independently of other nephrons.
The kidneys function on body fluid by filtering a substantial volume of blood (about one-fifth of the total cardiac output is pumped directly to the kidneys); this specific volume of blood is known as the "renal fraction." Blood flow through the kidneys of a typical adult male averages about 1.2 liters per minute. As the blood passes through the kidneys, the nephrons "clear" the blood plasma of unwanted substances--for example, the metabolic end products (such as urea, creatinine, uric acid, sulfates and phenols) and the nonmetabolic ionic substances (such as excess sodium, potassium, and chloride).
The nephrons are basically comprised of a capillary bed termed the "glomerulus," a second capillary bed known as the "peritubular" capillaries, and a urine-forming component known as the "tubule." The tubule is separated from the glomerulus by a membrane known as the "glomerular membrane." As the renal fraction of blood flows through the glomerulus, the glomerular membrane passes a small proportion (generally no more than 20%-25%) of the plasma comprising the renal fraction into the tubule. This filtered fluid then flows through the tubule, and towards the pelvis of the kidney, which in turn feeds into the bladder. As fluids flows through the tubule, most of the water and much of the electrolytes and other "wanted" substances are reabsorbed and returned to the blood; the "unwanted" substances (such as metabolic end products and excess water and electrolytes) pass into the bladder for elimination as urine.
The remaining portion of the renal fraction that does not cross the glomerular membrane exits the glomerulus and then enters the peritubular capillaries; from there, a portion of the renal fraction is generally returned to the venous system. The large quantities of fluid components reabsorbed in the tubules are also transported to the peritubular capillaries by diffusion through the tubular membrane.
While large quantities of fluid diffuse from the tubule into the peritubular capillaries for return to the vascular system, diffusion of some plasma components occurs in the reverse direction--from the peritubular capillaries to the tubules. For instance, sodium ions are actively transported across the tubular membrane and into the peritubular fluid, thereby conserving this important electrolyte. However, this creates a substantial negative charge within the tubule with respect to the peritubular fluid. In the proximal tubule, this electrical difference is approximately 20 millivolts, and can climb to as much as 120 millivolts in the distal tubule.
This difference in electrical potential potentiates diffusion of some positive ions, most notably potassium, from the peritubular fluid into the tubule. This flow of potassium into the tubules across the tubular membrane due to the electronegativity gradient is termed "passive secretion."
In addition to this passive secretion, some ionic materials are "actively" secreted into the tubules. For instance, para-aminohippuric acid (generally referred to as "PAH") is actively secreted from the peritubular fluid into the tubules; although only about twenty percent (20%) of the renal fraction passes into the tubules as glomerular filtrate, nearly ninety percent (90%) of any PAH in the blood is removed by the kidneys. Thus, approximately seventy percent (70%) of the PAH is removed from the plasma by active secretion into the tubules.
Occasionally, a kidney will become damaged and thus diminish or even cease its function of clearing the blood. Various renal function tests have been devised to assist a physician to evaluate the extent and type of kidney damage that has occurred. Also, these renal function tests are useful in evaluating whether a kidney is operating properly following a kidney transplant operation.
One such renal function testing procedure is known as intravenous scintigraphic urography (this procedure is also commonly known as a dynamic renal function imaging study). This procedure has historically involved the intravenous administration of a radioactively labeled iodine substance, such as I-131 ortho-iodohippurate (often referred to as "I-131 OIH"). Like PAH, I-131 OIH is rapidly removed from the blood by active tubular secretion in addition to glomerular filtration, thereby causing significant quantities of radiolabeled material to concentrate in the kidneys within a few minutes after administration. Images can be obtained using gamma scintillation cameras capable of showing the location of this radiolabeled material, and thereby giving a useful indication of the quality of renal function in the kidneys.
Despite the fact that I-131 OIH is an important tool in evaluating renal function, it suffers from some significant drawbacks. First, because of the high-energy gamma radiation output (364 KeV) of iodine-131 ("I-131"), the use of I-131 OIH results in images having poor spatial resolution. This makes it difficult to observe fine detail within the kidneys, and thereby limits the amount of useful information which is obtainable by this method.
Further, the renal extraction efficiency (the ability to clear the radiopharmaceutical from blood passing through the kidneys) of I-131 OIH is only about 65%-80%, and, while this is quite good, a higher extraction efficiency would result in higher kidney-to-background ratios, which facilitate detection of minimal renal function. In addition, I-131 emits a beta particle during radioactive decay which can cause damage to surrounding tissue. Further, because free radioiodine that accompanies I-131 OIH is readily taken up by the patient's thyroid gland, the maximum dose of I-131 OIH must generally be held to about 200 to 300 microcuries. This low dosage requires a significant exposure period when taking the radioactive image, which in turn decreases the temporal resolution of sequential images taken during renal function studies.
In order to improve upon the resolution obtainable in a radioactive renal function procedure, alternative radiolabeled materials have been earnestly sought. It is currently believed that the most desirable radioactive label is technetium-99m ("Tc-99m"), which has significantly improved resolution properties when compared to the I-131 label, because Tc-99m emits a lower energy (140 KeV) radiation. This lower energy radiation is well-suited for use in connection with standard radiation-measuring instrumentation. The radiation dose per millicurie is much less for Tc-99m than is the case when using I-131; this is because Tc-99m has a half-life of only about six (6) hours (as opposed to a half-life of eight (8) days for I-131), and also because Tc-99m does not emit beta particles during its decay process.
The radioactive properties of Tc-99m result from the transition of the metastable excited nucleus to ground state Tc-99. The resulting Tc-99 has such a long half-life (200,000 years) as to be virtually innocuous. As a result, dosages of as much as 30,000 microcuries of Tc-99m may be administered without danger to the patient. The result is that much shorter exposure periods are required than when I-131 OIH is used. This in turn makes it possible to take acceptable perfusion images during the first pass of radiopharmaceutical through the kidneys.
The foregoing properties of Tc-99m make it ideal as a tool in nuclear medicine, since it is well-suited for use with standard instrumentation, and because it subjects the patient with whom it is used to a relatively low dose of radiation.
Because of the demonstrated advantages of the Tc-99m label over the I-131 label, a great deal of effort has gone into developing a Tc-99m compound having a high renal extraction efficiency. A number of Tc-99m-labeled chelates have been reported in the literature.
One Tc-99m-labeled compound, Tc-99m diethylenetriaminepentaacetic acid (generally referred to as "Tc-99m-DTPA") has sometimes been used in radioactive renal function evaluation procedures because of its excellent imaging characteristics. However, Tc-99m-DTPA is not actively secreted into the tubules of .the kidney, and thus has a maximum extraction efficiency of only about 20-25%; this would be expected in connection with a substance entering the tubules only as a result of glomerular filtration. This lower extraction efficiency makes the use of Tc-99m-DTPA less sensitive in detecting mild renal disease than is I-131 OIH. Even so, because of the ability of Tc-99m-DTPA to provide perfusion images of the renal blood supply to the kidneys during the first pass after injection, it is common to use Tc-99m-DTPA together with I-131 OIH.
Another Tc-99m compound reported in the literature is Tc-99m-N,N'-bis (mercaptoacetyl)-ethylenediamine ("Tc-99m-DADS"). While this compound has been found to be secreted in the tubules, the tubular extraction efficiency of Tc-99M-DADS is only about 53% in normal patients, and even less in patients having decreased renal function. This very low extraction efficiency makes this compound unsuitable as a replacement for I-131 OIH.
Although Tc-99m-DADS is itself deemed unsatisfactory as a replacement for I-131 OIH, the fact that it is actively secreted by the tubules led to experimentation with various analogs. For instance, various methyl, hydroxymethylene, benzo, carboxylate, dicarboxylate, and benzocarboxylate analogs have been synthesized and tested.
Of these, the most efficiently excreted analog has been Tc-99m-N,N'-bis (mercaptoacetyl)-2,3-diaminopropanoate (Tc-99mCO.sub.2 -DADS). Unfortunately, this ligand exists as two stereoisomeric products upon chelation, referred to as Tc-99m-CO.sub.2 -DADS-A and Tc-99m-CO.sub.2 -DADS-B. Further, the Tc-99m-CO.sub.2 -DADS-B isomer was found to be far less efficiently removed by the kidneys than was the Tc-99m-CO.sub.2 -DADS-A isomer. Because of the inherent difficulty in separating these two isomers for clinical use, commercial development of Tc-99m-CO.sub.2 -DADS-A has proven to be impractical.
From the foregoing, it will be appreciated that it would be a substantial improvement in the field of renal function imaging if a Tc-99m compound could be provided that has a relatively high extraction efficiency, yet does not exhibit other adverse properties that would make it unsuitable as a replacement for I-131 OIH. Because of the short half-life of Tc-99m, it would also be a significant advancement if such Tc-99m imaging compounds could be easily prepared immediately prior to conducting a renal function diagnostic procedure. Such Tc-99m compounds and methods are disclosed and claimed herein.

Radiolabeled technetium chelates for use in renal function determinations


A front-loading and front-discharging, exclusively gravity-feed display device for upright articles includes an exclusively gravity-feed track of a U-shaped design in plan, a U-shaped cross-section open at the top thereof, and a generally uniform article-supporting longitudinal incline extending downwardly along the length of the track. In a preferred embodiment, the track defines a loading or supply end, and a dispensing or delivery end, the loading and dispensing ends being in generally the same vertical plane. A U-shaped bight track section is spaced from the same vertical plane. An upper track section functionally connects the loading end and the bight track section, and a lower track section functionally connects the bight track section and the dispensing end. The upper, bight and lower track sections cooperatively and successively define a downwardly-extending article-supporting incline along the entire U-shaped length of the track.

The present invention relates to a front-loading and front-discharging, exclusively gravity-feed display device for upright articles with functionally flat bottoms (e.g., bottles and cans), and more particularly to such devices which are easy to load and suitable for use on grocery store shelves.
It is well known to provide a front-loading and front-discharging, exclusively gravity-feed display device for upright articles with functionally flat bottoms, such as cans, bottles and the like. A basic example of such a device would be a single-channel display device that was tilted forwardly and downwardly, with loading and discharging of the articles being from the front thereof. A clear disadvantage of this construction is that, in order to load additional articles from the front of the device, each of the articles already on the device must be moved rearwardly and upwardly so as to make room for the added articles. Thus, loading of the device is a tedious, time-consuming and laborious task.
As a result, where access to the rear of the device is possible, such devices are typically rear-loaded, so that the loader simply has to drop the added articles into any of the available spaces behind the articles already on the track. Gravity then moves the added articles forwardly for a front discharge from the device. However, in many instances the rear of the device is simply not easily accessible for loading purposes, thus requiring the tedious, time-consuming and laborious loading process described above.
Further, in such a front-loading and front-discharging device there is no automatic rotation of the stock or merchandise on a FIFO (first-in first-out) basis; thus, there is a possibility of merchandise such as soda becoming stale or losing its freshness, as will occur on a store shelf over a period of months, even in an unopened bottle or can. Thus, a front-loading and front-discharging device of the type described requires store personnel to periodically rotate the stock on the display device in order to prevent stagnation.
U.S. Pat. No. 5,586,665 and U.S. Pat. No. 5,595,310 disclose front-loading and front-discharging, exclusively gravity-feed display devices for upright articles. Typically, these devices include a loading or supply end and a dispensing or delivery end. A U-shaped bight track section is provided along with an upper track section, which functionally connects the loading end and the bight track section, and a lower track section, which functionally connects the bight track section and the dispensing end. In both instances, the bight track section is elevated relative to the loading and dispensing ends. Each of the patents discloses an embodiment in which the articles are supported by their necks. The '310 Patent also discloses such a device without a neck-support system, so that the upright articles slide along the track of the device on functionally flat bottoms. However, in each case, it is necessary for the person performing the front-loading operation to push each of the articles from the loading inlet up an inclined track to the bight of a track curve (against the weight of all the articles already on that inclined track) before the added articles can commence to move by gravity from the bight or curve of the track to the dispensing outlet. In other words, in these devices the bottles do not move all the way from the loading inlet to the dispensing outlet under the influence of gravity.
Accordingly, it is an object of the present invention to provide a front-loading and front-discharging, exclusively gravity-feed display device for upright articles offering a rapid and easy loading operation.
Another object is to provide such a device wherein the loader does not have to move the new stock upwardly and rearwardly against the weight of all or even half of the articles already on the device.
A further object is to provide such a device which allows articles to move from the loading inlet all the way to the dispensing outlet under the influence of gravity.
It is another object of the present invention to provide such a device wherein all of the articles between the loading end and the dispensing end can be dispensed via a single dispensing end on a FIFO basis without any rotation or other adjustment of the articles on the device.


An object of the present invention is to provide a design-superposing display apparatus for superposing a design above a part of a display surface of a display device. The design-superposing display apparatus includes a design display portion disposed above the display surface for accepting a transmitted light from a rear thereof; a light source disposed outside of the display device for emitting the transmitted light of the design display portion; and a light guide portion extending from the rear of the design display portion toward the light source and guiding the emitted light toward the rear of the design display portion.

1. Field of the Invention
The present invention relates to a design-superposing display apparatus to superpose a design onto a part of a display surface of a display device, and a vehicle display unit utilizing the same.
2. Description of the Related Art
A projection type display unit such as head-up display (HUD) has been mounted on a vehicle. The HUD displays a virtual image on a windshield and superposes the virtual image on a foreground. The displayed virtual image is information which can not be displayed on a meter unit due to limited space therein. JP-2002-293162-A discloses a liquid crystal display (LCD) and a vacuum fluorescent display (VFD) as a display device for a HUD apparatus.
The colors of green, red, and blue are available for the VFD. Maximum luminance and lifetime of the respective colors is different. Only green has a required luminance for the HUD apparatus.
FIGS. 10A and 10B show a conventional VFD 100. A design W is formed in a display plane 101 transparent to a light emitted from an LED backlight 110 having a diffusion portion 112 and an LED 111.
The backlight method needs a space in a rear of the VFD 100. A heat sink is usually attached to a rear surface of the high luminance VFD 100. It is preferable to make a large contact area between the VFD 100 and the heat sink. The backlight method reduces the contact area due to a window in the heat sink to allow passage of the LED light, causing reduction of heat dissipation.

Design-superposing display apparatus and vehicle display unit


A hollow container having a top and a bottom and forming an internal cavity which is sized to accommodate an aseptic package, there being an opening in the container providing access to the cavity whereby the aseptic package can be inserted into the cavity and be positioned therein with its top adjacent the top of the cavity. A lid operable to retain the aseptic package within the cavity when closed and puncture projections which depend from the lid and project into the cavity so as to pierce the top of the aseptic package when the latter is positioned therein with its top adjacent the top of the cavity, the puncture projection forming an outlet for liquid to be drunk from within the aseptic package through the top of the container. The upper end of the outlet opens into the interior of a mouthpiece through which liquid is drunk from within the aseptic package within the container when the latter is being used. A rotary shut-off valve, rotatable between an open and a closed position, could also co-operate with the outlet.

This invention is concerned with aseptic packages which comprises semi-rigid beverage containers which are designed to be sealed after filling and which are provided with an area in their tops which is formed by a preforatable membrane which is to be perforated to enable the beverage to be consumed.
Often such aseptic packages are sold with a drinking straw. The membrane is to be pierced with the straw to open the package. The straw is then immersed in the beverage so that it can be drunk through the straw.
There is a risk of spillage either as the aseptic package is being opened or if it is squeezed once it has been opened. GB-A-2170791 discloses a teat unit having a tubular spike for insertion through the perforatable membrane of an aseptic package which is described as a parallelepipedic box formed from a paper/plastic laminate. The disclosed teat unit provides means for feeding a baby from the aseptic package without the necessity of first dispensing the liquid into a conventional feeding bottle. Such a teat unit suffers from the disadvantage that the liquid contents of the aseptic package spurt out as the spike is being inserted whilst the package is held in the hand. An object of this invention is to
There are larger aseptic packages from which the beverage is to be poured into a cup or mug for drinking rather than being drunk directly. U.S. Pat. No. 4,561,560 is concerned with a jug-like container for such an aseptic package, the container having a hinged lid which has depending puncture means associated respectively with a vent hole and an outlet through which liquid can be poured from the container, the outlet and the vent hole being formed in the lid which is arranged so that the puncture means pierce the top of an aseptic package placed within the container as the lid is closed, there being passages in each puncture means leading to the respective aperture whereby liquid contained in the aseptic package can be poured through the outlet via the respective passage in the puncture means. The lid is provided with a sliding closure member which is slidable to open or close the apertures. EP-A-0241632 discloses a similar jug-like container with a pouring spout for an aseptic package. GB-A-2135288 discloses a container which is adapted to enclose a milk or fruit juice carton and which is provided with a pouring spout and means to pierce the top of the carton.
GB-A-2046226 discloses a hollow container of generally rectangular cross-section having a top and a bottom and forming an internal cavity which is sized to accommodate a rectangular sealed package of beverage with semi-rigid walls and a penetrable wall, there being an opening in the container providing access to the cavity whereby the package can be inserted into the cavity and be positioned therein with its top adjacent the top of the cavity, and be removed therefrom, means operable to retain the package within the cavity, and puncture means which depend from the top of the container and project into the cavity so as to pierce the top of the package when the latter is positioned therein with its top adjacent the top of the cavity, the puncture means forming an outlet for liquid from within the package through the top of the container. This disclosure is mainly concerned with drinking the contents of a sealed bag or envelope of plastics material and provides means whereby that can be drunk directly from the bag through a straw or drinking tube which is inserted through the puncture means that are tubular. Such means are not suitable for use by a baby or infant.


An apparatus for compressing and transmitting both video and graphics portions of an interactive program guide (IPG). For an IPG that comprises a graphics portion and at least one video portion having audio associated with the video portion, the apparatus separately encodes the video and audio portion and the graphics portion. The video portion is slice-base encoded using a predictive encoder that produces a bitstream comprising intra-coded picture slices and predictive-coded picture slices. The graphics portion is separately slice-base encoded to produce encoded slices of the graphics image. To transmit an IPG, a transport stream is created containing the intra-coded and predicted picture streams as well as the encoded slices that comprise a graphics image that is to be included in the IPG. The receiver reassembles the components of the IPG into a comprehensive IPG.

1. Field of the Invention
The invention relates to communications systems in general and, more specifically, the invention relates to a video compression technique suitable for use in an interactive multimedia information delivery system.
2. Description of the Background Art
Over the past few years, the television industry has seen a transformation in a variety of techniques by which its programming is distributed to consumers. Cable television systems are doubling or even tripling system bandwidth with the migration to hybrid fiber coax (HFC) cable transmission systems. Customers unwilling to subscribe to local cable systems have switched in high numbers to direct broadcast satellite (DBS) systems. And, a variety of other approaches have been attempted focusing primarily on high bandwidth digital technologies, intelligent two way set top boxes, or other methods of attempting to offer service differentiated from standard cable and over the air broadcast systems.
With this increase in bandwidth, the number of programming choices has also increased. Leveraging off the availability of more intelligent set top boxes, several companies have developed elaborate systems for providing an interactive listing of a vast array of channel offerings, expanded textual information about individual programs, the ability to look forward to plan television viewing as much as several weeks in advance, and the option of automatically programming a video cassette recorder (VCR) to record a future broadcast of a television program. Unfortunately, the existing program guides have several drawbacks. They tend to require a significant amount of memory, some of them needing upwards of one megabyte of memory at the set top terminal (STT). They are very slow to acquire their current database of programming information when they are turned on for the first time or are subsequently restarted (e.g., a large database may be downloaded to a STT using only a vertical blanking interval (VBI) data insertion technique). Disadvantageously, such slow database acquisition may result in out-of-date database information or, in the case of a pay-per-view (PPV) or video-on-demand (VOD) system, limited scheduling flexibility for the information provider.
Therefore, it is desirable to provide a data compression and decompression technique that enables interactive program guides having graphics and video portions to be efficiently transmitted through an interactive information distribution system.

Method and apparatus for transmitting video and graphics in a compressed form


A heat generating container for use in a microwave oven or the like, which includes a metallic main container, a metallic lid to be detachably applied onto the metallic main container, and microwave absorbing heat generating film layers formed on outer surfaces of the metallic main container and metallic lid.

The present invention generally relates to a high frequency heating arrangement and more particularly, to a heat generating vessel or container for use in a microwave oven which is one example of high frequency heating apparatuses, so as to generate heat through projection of microwaves irradiated from a magnetron (i.e., a high frequency generating means) for heating an object to be cooked, and also for baking thereof.
A microwave oven is a cooking apparatus arranged to guide microwaves emitted from a magnetron into an oven interior or heating chamber for irradiation onto an object to be cooked so as to effect cooking by causing said object itself to generate heat.
However, there are some items to be cooked which are not suitable for direct heating by microwaves such as those requiring scorched portions or those to be subjected to cooking after expediting fermentation by raising the temperature thereof.
In order to deal with the cooking items as referred to above, there has been proposed a microwave oven further provided with a sheathed heater in the heating chamber so as to make it possible to subject the item to be cooked to heat treatment through utilization of heat irradiated from said sheathed heater besides the microwave radiation.
In the microwave oven of the above described type, however, since two kinds of heating means, i.e., the magnetron and the sheathed heater, must be provided as heat sources, not only cost increase is involved thereby, but the construction of the microwave oven is undesirably complicated, with a consequent increase in the size of the apparatus on the whole.
Therefore, in order to overcome the various problems as described above, there has been recently developed a heat generating member composed of a plate in a double layer construction formed by laminating a heat generating substance (e.g., silicon carbide, ferrite or the like) which generates heat through irradiation of microwaves and an inorganic heat insulating base material (e.g., glass, ceramic or the like). There has also been proposed a heat generating member made of a silicon carbide group ceramic molded plate.
The microwave oven employing the heat generating members of the above described type is capable of effecting both the dielectric heating and the heating by heat radiation, only through irradiation of microwaves and is referred to as a multi-function microwave oven.
Incidentally, due to the fact that a so-called "home bakery" or household bread baking unit has recently become a popular article, a microwave oven provided with a bread baking function has been studied and manufactured as an actual product commercially available.
Although a bread baking container or hopper (referred to as a hopper hereinafter) to be disposed in the oven interior or heating chamber of the microwave oven is generally arranged to be heated indirectly, this practice requires parts for subjecting heated air to convection for efficient conduction of heat to the hopper, and thus, not only cost increase is involved thereby, but power consumption is undesirably raised due to poor heating efficiency, even when the heat is conducted in an efficient manner.
On the other hand, as a direct heating practice, there has conventionally been proposed an arrangement in which a microwave absorbing heat generating material is applied over an outer surface of a hopper as disclosed in Japanese Patent Laid-open Publication Tokkaisho No. 58-52916, or another arrangement in which a microwave absorbing heat generating material is coated on a ceramic or glass container as disclosed in Japanese Patent Laid-open Publication Tokkaisho No. 58-52917.
However, the known arrangements as described above have such problems that uneven baking (or scorching) may take place or yeast for fermentation is undesirably killed if applied to the bread bakery, since microwaves are transmitted into the container.
Meanwhile, since some of the conventional multi-function microwave ovens effect both functions for the microwave heating and the heating by heat radiation only by irradiation of microwaves, with the heating by heat radiation not killing yeast as in the microwave heating, they are applied to a bread baking device widely employed recently as well as to composite cooking. Such known bread baking device includes a hopper for accommodating materials such as flour and the like, to be disposed on a bottom plate in the heating chamber of the microwave oven, with the outer face of the hopper being coated by a microwave absorbing heat generating material, a kneading device having a stirring blade and provided under the hopper, and a metallic open-close lid of a clip fixing type provided at the upper portion of the hopper for shielding microwaves, and an outer cover made of a heat-resistance glass or the like for enclosing the above arrangement therein.
The known bread baking device as described above, however, has such disadvantages that, since the microwave absorbing heat generating material is coated over the entire outer surface of the hopper and the upper portion of the hopper is shielded by the metallic open/close lid, without provision of any turntable or stirrer fan, irradiation of the microwaves from the upper portion through the outer cover, onto the microwave absorbing heat generating material becomes uneven, and thus, there is a possibility that the heat generating material at portions subjected to much microwave irradiation is melted due to local overheating, while it is difficult to uniformly scorch the entire surface of the bread to be prepared. Moreover, owing to the fact that the heat generating material is directly coated onto the outer surface of the hopper, said material tends to be subjected to various damages, e.g., separation, cracking by sintering, etc., arising from handling, such as grasping of the hopper during taking out the bread, careless collision thereof with other utensils, washing of the hopper by brushes, etc. after use, thus presenting problems from the aspect of durability. Furthermore, since the open/close lid at the upper portion of the hopper is of the clip fixing type, there is such a possibility that the bread swelling at the finished stage is compressed by the open/close lid for bursting upon releasing of the clip.

Heat generating container for microwave oven


In the semiconductor laser diode, a first material layer, an active layer, and a second material layer are sequentially formed on a substrate, a ridge portion and a first protrusion portion are formed on the second material layer in a direction perpendicular to the active layer, the first protrusion portion being formed at one side of the ridge portion, a second electrode layer is formed in contact with a top surface of the ridge portion, a current restricting layer is formed on an entire surface of the second material layer and exposes the second electrode layer, a protective layer is formed on a surface of the current restricting layer above the first protrusion portion and has an etch selectivity different from that of the current restricting layer, and a bonding metal layer is formed on the current restricting layer and the protective layer in electrical connection with the second electrode layer.

1. Field of the Disclosure
The present disclosure relates to a semiconductor laser diode and method for manufacturing the same, and more particularly, to a semiconductor laser diode and method for manufacturing the same that can prevent stress concentration on a ridge portion during a flip-chip process.
2. Description of the Related Art
Since semiconductor laser diodes have a smaller size and a low threshold current lower for laser oscillation than conventional laser devices, they are widely used for high speed data transmission, recording, and reading in the field of telecommunications and in laser disc players. Particularly, nitride semiconductor laser diodes provide waves in a green to ultraviolet region, such that they are widely used for various applications such as high density optical data recording and reproducing, high-resolution laser printers, and projection TVs.
FIG. 1 shows a semiconductor laser diode disclosed in U.S. Patent Application Publication No. 2004/0174918 A1. Referring to FIG. 1, a semiconductor laser diode includes a first material layer 120, an active layer 130, and a second material layer 140 that are sequentially formed on a substrate 110. The first material layer 120 includes a buffer layer 121, a first cladding layer 122, and a first waveguide layer 123 that are sequentially formed between the substrate 110 and the active layer 130. The second material layer 140 includes a second waveguide layer 141, a second cladding layer 142, and a cap layer 143 that are sequentially formed from the active layer 130. On an upper portion of the second material layer 140, a ridge portion 151 and a protrusion portion 152 are formed. The ridge portion 151 and the protrusion portion 152 include upper portions of the second cladding layer 142 and the cap layer 143. Also, a P-type second electrode layer 171 is formed on the cap layer 143 of the ridge portion 151. The protrusion portion 152 is formed at a similar height as the ridge portion 151 to prevent stress concentration on the ridge portion 151 during a flip-chip process. Therefore, stress can be effectively distributed when the semiconductor laser diode is flip-chip bonded to a submount (heat discharge structure), such that light can be uniformly emitted over an entire ridge waveguide region. Further, a current restricting layer 160 formed of dielectric material is formed on the surfaces of the second cladding layer 142, the protrusion portion 152, and the ridge portion 151 for controlling a lateral mode. The current restricting layer 160 exposes the second electrode layer 171 formed on a top surface of the ridge portion 151. In addition, a bonding metal layer 172 is formed on surfaces of the current restricting layer 160 and the second electric layer 171, and an N-type first electrode layer 182 is formed on an exposed surface of the buffer layer 122 that has a stepped portion beside the bonding metal layer 172.
To manufacture the semiconductor laser diode having the aforementioned structure, the first material layer 120, the active layer 130, the second material layer 140, and the second electrode layer 171 are sequentially formed on the substrate 110. Next, the ridge portion 151 and the protrusion portion 152 are formed by etching, and the current restricting layer 160 is deposited entirely over the ridge portion 151 and the protrusion portion 152. Next, a top surface of the second electrode layer 171 is exposed by photolithography with a photoresist and by etching. Then, the bonding metal layer 172 is deposited.
In this manufacturing method, however, the ridge portion 151 has a narrow top width of about several micrometers. Thus, it is difficult to precisely pattern the photoresist to expose the second electrode layer 171 during the photolithography, thereby reducing process stability.
Meanwhile, if the second electrode layer 171 is exposed by planarization, the current restricting layer 160 formed on the protrusion portion 152 is also removed by over etching. Thus, the protrusion portion 152 formed of p-GaN can be exposed. FIG. 2 is an SEM photograph showing an exposed corner "A" of the protrusion portion 152 due to over etching of the current restricting layer 160 during etch-back planarization, which is performed without preparing a protective layer above the current restricting layer 160 located on the protrusion portion 152 before forming the bonding metal layer 172 on the semiconductor laser diode of FIG. 1. As a result, if the bonding metal layer 172 is formed on the exposed protrusion portion 152, the bonding metal layer 172 makes contact with the protrusion portion 152 of the second cladding layer 142 to thereby cause current leakage.

Semiconductor laser diode and method for manufacturing the same


A distributed monitoring and protection system for a distributed power network. The system includes a plurality of high-speed measuring units (MUs), wherein each MU is coupled to a power line to measure values of electrical parameters of the power line. Electrical parameters, such as current, voltage, power and frequency are measured by the MUs. The MUs communicate with a control unit (CU) over a high-speed communications network. The CU includes a processor executing algorithms for evaluating the measured parameters to determine the status of the power network and the MUs. The processor also executes fault detection and isolation by comparing the measured values against predetermined threshold values. When a fault is detected by the CU, protective action, such as tripping of a circuit breaker, may be initiated by the CU directly or by transmitting the tripping command over the high speed data network to a local MU. The local MU may then trip the circuit breaker. The availability at the CU of concurrent measurements from the plurality of MUs enables improved coordination and sequencing of protective actions.

Electric power is typically conveyed from electric power generators to users via a network of transmission and distribution circuits. Electric power is commonly generated as three-phase alternating current (AC) at a frequency of 50 Hz or 60 Hz. Each phase requires a current-carrying wire, and has voltage and current nominally lagging or leading any other phase by 120 degrees. Power is generated, for example, at 4 kV voltage, stepped up to 128 kV or 750 kV for transmission over long distances, and then stepped down in stages to 4 kV or 33 kV for distribution to various neighborhoods. Voltage may further be reduced, by pole-mounted or pad mounted transformers, for delivery at 120V and 240V to residential and commercial users within these neighborhoods.
Large voltage transformations typically take place at transmission or distribution substations. Functions of the substations may include voltage transformation, regulation and control, power-factor (e.g. capacitor-bank) and load balancing, monitoring, and protection of hardware. Proper monitoring and protection is extremely important in preventing damage to equipment, reducing hazards and minimizing the number of users who may have to be disconnected from an electric distribution network due to damage or equipment failures. Conventional protection systems include fuses and relays, each having predetermined response times and zones of control to minimize propagation of failures.
Fuses are located throughout the electric distribution network and disconnect circuits experiencing excessive current flow due to equipment failure, storm damage, etc. Each fuse is selected with a predetermined response time to accommodate the need of the circuit being protected. The fuse does not blow under normal operation or a momentary over-current condition, but is designed to blow under a true, sustained fault situation. Relays are similarly used to detect faults and initiate disconnection of faulted circuits; relays, however, are typically more complex than a fuse. A relay typically includes a voltage and/or current sensor and a set of electrical contacts driven by the sensor. Electrical contacts in the relay may be connected to circuit breakers which, in turn, physically disconnect faulted lines or circuits when the breaker is opened (xe2x80x9ctrippedxe2x80x9d). Modern relays may use solid state switches in place of electrical contacts.
There are many types of relays, each having different characteristics. Depending on its electrical and physical characteristics, the response time of the relay may be varied. For example, a relay may be made to trip a breaker in one or two cycles of the 50 Hz-60 Hz frequency when it detects excessive current. This type of relay is known as an instantaneous over-current (OC) relay (Type 50). Another type of relay is the time-over-current (TOC) relay (Type 51). The TOC relay may include an adjustable delay so that it may respond quickly to large over-current conditions, but more slowly to small over-current conditions. Predetermined response curves (TOC Curves) are usually provided by the manufacturer of the relay to aid in the selection and adjustment of a Type 51 relay.
Small current overloads in a local circuit may be tolerated if the magnitude and duration of the overload are not expected to damage the distribution network. For example, temporary overloads lasting a few hours may be acceptable in order to maintain service to users during a hot summer day when peak load periods are expected. Concurrent with maintaining service during expected overload conditions, the relay must still effectively protect the network in the event of a true, sustained circuit fault. Some networks may use a Type 50 relay in parallel with a Type 51 relay to provide better response to large fault currents, while not over-reacting to small, temporary overloads.
Relays are installed at various locations in a network. With respect to electromechanical relays, each protective function for one phase of a circuit generally requires a separate relay. Providing separate relays for each function per phase is expensive, because of space requirements and installation/wiring costs for so many relays. More recent designs provide for microprocessor-based relays. Microprocessor-based relays are able to combine protective functions for all three phases into one unit. Furthermore, microprocessor-based relays may be remotely reset and adjusted to provide responses that vary depending on the nature of the electrical load during the year. For example, TOC curves and operating points may be changed in anticipation of changes in loads.
A conventional relay, either electromechanical or microprocessor, only senses current or voltage on a circuit to which the relay is connected and only disconnects a breaker for that circuit. The relay does not communicate its measurements with any other relay during the period in which it senses a fault and trips the breaker. Some relays may communicate status information, but do not share measurements to make protective decisions. Using TOC curves, for example, is one of the important ways to limit the relay""s xe2x80x9czone of controlxe2x80x9d. For example, relays protecting the spokes or xe2x80x9cfeedersxe2x80x9d of a radially distributed power network may be adjusted to respond faster (and at lower trip currents) than relays protecting the hub of the network. In this manner, a faulted feeder may be disconnected before disconnecting the hub and, consequently, all the remaining feeders.
FIG. 1 illustrates a conventional electric utility network protected by relays. As shown, a 128 kV transmission line feeds the primary windings of each of two power transformers 30 and 31 by way of circuit breakers 18 and 24, respectively. The secondary of each of the two power transformers 30 and 31 feeds electric power at 13 kV to feeder bus 1 and feeder bus 2, respectively. Feeder bus 1 transmits electric power at 13 kV by way of two circuit breakers 44 and 52 to two feeders, feeder #1 and feeder #2. Similarly, feeder bus 2 transmits electric power by way of two circuit breakers 47 and 55 to two feeders, feeder #3 and feeder #4. Feeders #1-#4 provide power, for example, to a neighborhood, factory or shopping center. Tie-breaker 40 provides an alternative path of electric power in the event that power transformer 30 or power transformer 31 is taken out of service. It will be appreciated that each power line shown in FIG. 1 represents three power lines corresponding to the three phases of electric power. Depending on the network, there may actually be three times the number of breakers and relays shown in FIG. 1.
Also shown in FIG. 1 are current transformers 14, 16, 32, 34, 41, 42, 50 and 51 feeding current to various relays. The current transformers each provide an output current in proportion to the current flowing through each line. For example, the current flowing through a line may be 1200 amperes, whereas the corresponding current transformer may provide an output of 5 amperes. As shown, current transformer 14 provides current to OC relay 20, TOC relay 21 and differential relay 22. Differential relay 22, which also senses current from current transformer 32, reacts to an imbalance between current flowing into and out of power transformer 30. OC relay 20, TOC relay 21 and differential relay 22 control breaker 18, and each may individually trip the breaker if a predetermined condition occurs. Similarly, OC relay 26, TOC relay 27 and differential relay 28 control breaker 24. OC relay 45 and TOC relay 46 control breaker 44. OC relay 48 and TOC relay 49 control breaker 47. OC relay 53 and TOC relay 54 control breaker 50. OC relay 56 and TOC relay 57 control breaker 55.
Also shown in FIG. 1 are under-voltage relays 37 and 39 connected to potential transformers 36 and 38. Under-voltage relays 37 and 39 are shown connected to the secondary of each potential transformer to protect against transformer failures or other failures in the circuits. A potential transformer provides an output in proportion to voltage on the feeder bus, but at a stepped down voltage level. For example, a bus voltage of 13 kV may be stepped down to an output voltage of 120V. Two additional relays shown are under-frequency relays 60 and 62 controlling breakers 18 and 24, respectively. An under-frequency relay protects against excessive line frequency deviations.
As discussed above, conventional protection in a network requires that relays be selected and adjusted so that a fault in the network may be contained. For example, if there is a fault on feeder #1 at a local neighborhood (at the spoke level), relays 45 or 46 should trip breaker 44 before relay 20, 21, 22, 37 or 60 causes breaker 18 to trip (at the hub level). If the relays have been adjusted properly, feeder #1 is disconnected, but feeder #2 continues to provide electric power. If the relays on feeder #1, however, do not trip their associated breaker fast enough, the relays ahead of power transformer 30 will likely trip their associated breaker, thereby cutting power to both feeder #1 and feeder #2. Similarly, if the relay ahead of power transformer 30 do not trip due to a fault at the power transformer or on feeder #1, the entire transmission line and substation may be shut down by another relay positioned higher in the hierarchy of the network.
A need exists, therefore, for an apparatus and method for improved detection of and protection against electric faults in a power network. A need also exists for eliminating the complexity of selecting and adjusting the tripping characteristics for relays and breakers in a power network. A need also exists for an improved method for coordinating and sequencing protective actions and breakers in a power network.
To meet this and other needs, and in view of its purposes, the present invention provides a distributed monitoring and protection system for a distributed power network. The power network has a plurality of lines for transmitting electric power from a station with circuit breakers included in the lines. The distributed monitoring and protection system includes at least one monitoring unit coupled to at least one of the plurality of power lines for measuring electrical parameters of the power line; and at least one control unit communicating over a data network with the monitoring unit and receiving measured electrical parameters from the monitoring unit. The control unit includes a processor for analyzing the measured electrical parameters and tripping at least one of the circuit breakers when a fault in the power network is determined.
The measured electrical parameters include values as a function of time for current, voltage, power, frequency, power factor, and harmonic components of the current and voltage in the power line. The measurements are obtained by the monitoring unit, communicated over the data network, and analyzed by the control unit in a sufficiently short time to activate protective devices and thereby limit the effects of a fault in the power network. Preferably, the measurement and communication times are each one cycle or less of the alternating current power network.
It is understood that the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.

Distributed monitoring and protection system for a distributed power network


A method and apparatus is disclosed herein for asynchronous space-time coded transmission from multiple stations. In one embodiment, the method comprises one or more terminals and at least two base stations wirelessly communicating information-bearing signals to the one or more terminals using orthogonal space-time block codes. In one embodiment, the proposed codes maintain “orthogonality” at the receiver even in the presence of asynchronous signal reception among signals transmitted from distinct transmit base stations.

A number of recently developed techniques and emerging standards are based on employing multiple antennas at a base station to improve the reliability of data communication over wireless media without compromising the effective data rate of the wireless systems. Specifically, recent advances in wireless communications have demonstrated that by jointly encoding symbols over time and transmit antennas at a base station, one can obtain reliability (diversity) benefits as well as increases in the effective data rate from the base station to each cellular user. These multiplexing (throughput) gain and diversity benefits depend on the space-time coding techniques employed at the base station. The multiplexing gains and diversity benefits are also inherently dependent on the number of transmit and receive antennas in the system being deployed, in the sense that they are fundamentally limited by the multiplexing-diversity trade-offs curves that are dictated by the number of transmit and the number of receive antennas in the system.
In many emerging and future radio networks, the data for any particular cell user may be available to multiple base stations. Viewing each of the base stations with data for a particular user as an element of a virtual antenna array suggests using cooperative signal encoding schemes across these base stations to provide diversity benefits to the desired user. Thus, when transmitting the same data from two active base stations, each active base station must encode its data independently. Since the encoded signals, however, are transmitted by spatially dispersed base-stations, they arrive at the receiver with distinct relative delays with one another, i.e., asynchronously. That is, there can be a lack of time-synchronization between the transmissions from different base stations to the receiver. This asynchrony can arise due to the fact that the individual base stations may be operating independently, but also due to the fact that even if the signals the signals transmitted from spatially dispersed base stations to a receiver are transmitted synchronously, they may arrive asynchronously at the receiver. Although these relative delays can, in principle, be estimated at the receiver, they are not known (and thus cannot be adjusted for) at the transmitting base stations, unless there is relative-delay information feedback from the receiver to the transmitting base stations.
A large collection of space time block codes (STBCs) have been proposed in recent years as a way of providing diversity and/or multiplexing benefits by exploiting multiple transmit antennas in the forward link of cellular systems. Given the presence of n transmit antennas, the typical objective is to design STBCs that provide order-"n" transmit-antenna diversity in the system. Typical STBC designs transmit an antenna-specific block of t samples per antenna for each block of k information symbols. Such STBC designs are described by a STBC matrix with t rows and n columns, whereby the (i,j)th entry denotes the sample transmitted by the antenna j at time i. Of interest is the actual symbol rate of the STBC scheme, R, which is equal to k/t (i.e., the ratio of k over t). Full rate STBCs are STBCs whose rate R equals 1 symbol per channel use. Another important attribute of a STBC is its decoding complexity.
Existing orthogonal space-time block codes that have been designed and optimized for the synchronous setting perform poorly, in general, in the asynchronous non-collocated antennas setting. For instance, it is well known that the Alamouti code is the best space-time block code for a two-transmit one-receive antenna system. Although the Alamouti code provides full rate, full diversity, maximum coding gain, and symbol-by-symbol decoding in the synchronous setting, it provides no spatial diversity in the case that there is a one-sample relative delay offset at the receiver between the signals transmitted by the two base-stations. This observation is more general, in that, codes that have been optimized for the synchronous setting perform, in general, poorly in the presence of relative delay offsets in the arrival times of signals transmitted from different base stations. For more information on Alamouti codes, see S. M. Alamouti, "A simple transmitter diversity scheme for wireless communications," IEEE Journal Selected Areas in Communications, pp. 1451-1458, October 1998.
One class of designs for transmitting to a receiver from n potentially asynchronous base stations has been presented in S. Wei, D. Goeckel, and M. Valenti, "Asynchronous cooperative diversity," Proceedings Conf. Information Sciences and Systems, Princeton University, March 2004. The proposed method employs space-time block coding with BPSK modulation without reducing the symbol rate. The resulting full-rate schemes rely on the presence of a Viterbi decoder at the receiver in order to be able to provide full diversity at the receiver regardless of the delay offset, provided however that it does not exceed a predetermined value L. Despite being a full-rate full-diversity scheme, this technique inherently possesses a number of important limitations. First, the data block size and the decoding complexity of the proposed algorithms, required to obtain full spatial diversity are both exponential in the delay parameter, L; hence, the decoding complexity and delay become prohibitively expensive fast as the number of transmit base stations increases. Second, although full rate in the sense that 1 symbol is communicated per channel use, these schemes only work with BPSK modulation (which, being a real-valued modulation scheme, uses only half of the available degrees of freedom); as a result, the rate of these schemes is equivalent to that of half-rate QPSK schemes (which use both dimensions in the complex plane to modulate symbols).
Another class of approaches exploits space-time trellis code designs that are designed to provide full diversity regardless of the relative delay subject to maximum allowable relative delay offset, L. These codes exploit constructions based on shift-full rank matrices that guarantee that the matrices provide full diversity regardless of the relative delay set. Although they provide full diversity subject to a set of relative delays with only a small overhead in data rate, these designs have some important limitations. First, the decoding complexity of these designs is exponential both in the number of antennas, and the parameter L. Second, the design is modulation scheme specific. Finally, they are guaranteed to provide full diversity subject to relative delay offsets that are integer multiples of the symbol duration. Strictly speaking, however, there are no guarantees for relative delays that are fractions of the symbol duration.
Although the decoding complexity of the optimal decoder for arbitrary STBCs is exponential in the number k of jointly encoded symbols, there exist designs with much lower complexity. One such attractive class of designs, referred to as orthogonal space-time codes (OSTBCs), can provide full diversity while their optimal decoding decouples to (linear processing followed by) symbol-by-symbol decoding. Full rate OSTBCs exist only for a two transmit-antenna system. For three or more antennas, the rate cannot exceed ¾ symbols/per channel use. This rate is achievable for n=3 and n=4 antennas. For more than four antennas the highest-rate OSTBCs are not known in general. In general, a rate equal to ½ symbols/channel use is always achievable, but, often, higher rates may also attainable for specific values of n.
Classes of systems that have been employed in Europe for broadcasting common audio/video information from several base stations are exploiting coded OFDM transmission under the umbrella of the single frequency network (SFN) concept (e.g., see J. H. STOTT, J. H., 1996. "The DVB terrestrial (DVB-T) specification and its implementation in a practical modem," Proceedings of the 1996 International Broadcasting Convention, IEE Conference Publication No. 428, pp. 255-260, September 1996). These systems employ a common coded OFDM based transmission from each of the broadcasting base-stations. The OFDM based transmission allows asynchronous reception of the multitude of signals and provides increased coverage. However, as all base-stations transmit the same coded version of the information-bearing signal, SFN systems do not provide in general full transmit base-station diversity (some form of it is available as multi-path diversity, although limited).
A class of schemes includes space-time bit-interleaved coded modulation systems with OFDM and can provide both spatial diversity and can cope with asynchronous transmission. Although these schemes can provide full diversity and very good data rates, they are disadvantageous because the decoder complexity of such schemes grows exponentially with the number of transmit antennas used over all the base stations, and the number of bits/per symbol in the employed modulation scheme.

Method and apparatus for asynchronous space-time coded transmission from multiple base stations over wireless radio networks


The application of a treating solution containing polyhydroxy compound and choline chloride to a fibrous cellulosic material is made more uniform and reproducible by including in the treating solution a colorizing amount of a fugitive tint, by which the uniformity of the application can be observed and corrected by appropriate changes to the operating variables.

Anionic dyes, such as fiber reactive dyes and direct dyes, are currently employed for dyeing cellulose fibers because of their wide shade range, ease of application, and adequate wet fastness properties for many end uses.
There are, however, certain environmental problems related to the utilization of such dyes, which occur because high amounts of electrolyte and alkalinity must be used, and the relatively poor uptake of such dyes into the cellulosic fibers. Depending on the application method, shade depth and dye type, only 50-75% of the dye becomes attached to the substrate using conventional dyeing methods. Consequently, dyehouse effluents contain an unacceptably high level of unfixed dye, electrolytes and alkaline residues which can cause environmental hazards, and compliance problems with EPA discharge standards.
The above-described problems were addressed in part by Weltrowski et al in U.S. Pat. No. 5,501,711 by mildly oxidizing the fibers, subjecting the oxidized fibers to reduction with a solution of chitosan oligomers, stabilizing the chitosan-treated fibers by addition of a reducing agent, such as dimethylol dihydroxyethyleneurea (DMDHEU), and then dyeing the thusly treated fiber. This process involves 4-5 steps, and even then does not address the problems of dye fastness and the high cost of the chitin treatment. This process represents a substantial improvement in dye pickup, and therefore improved dye exhaust from the dye bath. However, the discharge of metals into dye bath effluents remains a particularly troublesome problem, because so many dyes contain substantial quantities of metals. For example, many blue dyes contain copper, and many brown dyes contain chromium. In addition, some dyes contain such metals as cobalt and magnesium.
Traces of catalyst are a still further source of metallic contaminants from dye bath effluents. Furthermore, certain analogs, such as N-3-chloro-2-hydroxypropyltrimethylammonium chloride, may produce toxic amounts of epichlorohydrin when they are contained in alkaline solutions. Therefore, still further improvements were needed to improve dye uptakes, to reduce electrolyte concentrations in the dye bath, and to reduce the quantity and toxicity of the discharge from the dye bath, in each case without sacrificing the dyeability of the cellulose fiber.
Copending U.S. patent application Ser. No. 08/867,132, of which this application is a continuation-in-part, addresses the above-described problems by applying to the cellulosic material an aqueous treating solution comprising (a) a cyclic polyhydroxy compound, (b) choline chloride and (c) a crosslinking catalyst. However, in order for the treatment to be effective it is necessary that the treating solution be applied to the material being treated in a highly consistent manner. The reasons for this are two-fold: (1) to facilitate the uniform application of subsequent treating materials; and (2) to identify and reproduce color and surface effects consistently.

Method and compositions for treating fibrous cellulosic materials


A bilge keel design for improved ship roll damping performance. The bilge keel has a porous region substantially at a forward end, and is designed to alleviate and mitigate added drag from flow misalignment due to scale effects and variation in vessel speed and loading conditions. The bilge keel design is use on both port and starboard sides of the vessel hull.

Since the mid-1800s, ships have used bilge keels to mitigate roll motions due to waves. The use of bilge keels to minimize ship roll motion was first suggested by Froude. Historically, bilge keels have featured flat plate designs, and later also included discontinuous fin or wedge type designs along the ship's length. Conventional bilge keels are used to mitigate and dampen small to moderate roll motions.
A bilge keel is a projection like a fin extending from the fore to the rear part of the hull around the turn of the bilge on both sides of the ship. Bilge keels should be situated so that they do not strike the wharf or another vessel when tying alongside. Bilge keels are usually constructed from flat plates the form a sharp obstruction to the roll motion. The bilge keel itself should be aligned with the flow streamline of the moving ship so that its effect on the resistance is minimal.
The alignment can be determined by an oil dot flow technique during the initial resistance experiments. Visualization studies can be performed with tuffs placed on the hull surface during the resistance tests to aid and confirm the adequacy of the bilge keel alignment. The bilge keel alignment test is typically conducted at the ship design speed and a design craft displacement with the model tested in Froude scale.
A moving ship will induce a boundary layer along the hull surface. The boundary layer velocity profiles are sensitive to Reynolds scale. By testing a model in Froude scale, the Reynolds numbers can differ by two orders of magnitude between ship and model. The streamline orientation can differ noticeably between full-scale and model-scale due to large difference in Reynolds number. Bilge keels that are carefully aligned with streamlines during the model tests may experience an angle of attack on the full-scale vessel due to difference in boundary layer profiles along the ship hulls. The misalignment in flow field and bilge keel placement will induce added drag on bilge keels.
Similarly, craft displacement may change over the life of the vessel or even change during missions as fuel is consumed during the voyage. The distribution of weight on the vessel may also change. The change in displacement and weight distribution will change the craft sinkage and trim, which will shift the flow patterns around the hull and change the flow into the bilge keels. An added drag on bilge keels is induced by the misalignment of the flow direction with the bilge keel orientation. The same comments on Reynolds number effects are applicable to the effects of ship speed changes. In addition to the design speed, a ship is often operated at different ship speeds for different mission requirements. The change in ship speeds can change ship trim angle and flow streamline orientation, which can lead to an increase in the added drag on the bilge keels. It is desired to have a simple and effective bilge keel design with enhanced roll stabilization that alleviates added bilge keel drag, and reduces fuel cost due to changes in craft loading condition, ship speed, and Reynolds scale effects on boundary layer velocity profiles as described above, and generally accommodates for changing environmental conditions.

The United States of America as represented by the Secretary of the Navy


A computer system includes a plurality of central processing units (CPUs) each of which has a direct napped cache memory. The system also includes a main memory, and one or more display frame buffers. The cache normally operates in a write back mode, whereby updated data is written back to main memory only when a cache block is reallocated to store a new block of data. A tag for each block of data stored in the cache includes a Shared flag which indicates whether the corresponding block of data may be stored in the cache of another CPU. When a block of data stored is modified, it is immediately written to main memory if the tag for that block has an enabled Shared flag. To make the cache operate in a write-through mode for blocks of image data, the system stores an enabled Shared flag in the cache whenever a block of frame buffer data is stored in the cache. A circuit in the cache detects when the CPU is writing an entire block of image data to an address in the frame buffer and causes the cache to write the block of image data directly to the frame buffer without storing the image data in the cache. An address circuit in the cache stores image data from the frame buffer only in a predefined fraction of the cache, and thereby restricts the amount of other data stored in the cache which may be displaced by image data.

Referring to FIG. 1, a system 100 containing high-performance central processing units (CPUS) 102, 104, 106 will usually provide a cache memory 112, 114, 116 for each CPU. The system may also include other types of processors, such as an input/output processor 118. A cache memory increases the CPU's performance by satisfying most of the CPU's memory references, instead of requiring a reference to main memory 120 for every reference made by the CPU. Since the access time of the cache (e.g., 10 nanoseconds) is usually much less than the access time of main memory (e.g., 400 nanoseconds), performance is increased.
In a multiprocessor system in which a number of processors 102-106 and their caches 112-116 share a common memory bus 122, the caches also serve to shield the bus from the memory traffic generated by the CPUS. A "write back" strategy, which returns a cache block to main storage 120 only when the cache block is needed for another address, is a particularly effective method of reducing bus traffic.
With the availability of dual-ported dynamic memories, commonly known as video RAMS, it has become straightforward to build frame buffers 124, 126 that place the display pixelmap (also known as a bit map) in the physical address space of one or more CPUS. The video RAMs in such frame buffers have a serial port, which is used to refresh a raster-scanned monitor 130 or 132, and a parallel port used by the CPUs for updating the image data stored in the video RAMs. Using the CPU to update the contents of the frame buffers can represent a substantial savings over using specialized hardware, and the rate at which updates to an image can be computed and stored in a frame buffer is quite respectable using currently available high performance CPUs.
When a write-back cache is used in conjunction with a memory-mapped frame buffer, three problems can occur.
The first problem with using a write-back cache in conjunction with a frame buffer is that data values in the cache are not written back to the frame buffer until the cache block holding the frame buffer data is needed to hold some other block of data. Thus changes to the image on the display may be delayed for an arbitrary amount of time after the pixelmap is modified by the CPU. In other words, the displayed image may not reflect the computed image data for an unpredictable period of time.
The second problem is that caches frequently fetch an entire block of information from main memory whenever the cache does not contain a referenced address, even when the operation issued by the CPU is a write operation. For normal programs, this is a good strategy, since most locations are read before they are written. In a frame buffer, this is frequently not the case, and locations are often written without being read first. In this case, the data fetched into the cache will be overwritten immediately, so the fetch represents wasted work.
The third problem concerns the tendency of frame buffer data to displace other data blocks needed in the cache. In a direct mapped cache the data stored in a particular address in main memory can be stored in only one location in the cache. Direct napped caches are frequently used because they are effective and lower cost than other cache mapping organizations. Unfortunately, when a direct mapped cache is used with a frame buffer, overall system performance may be severely degraded. The reason for this is that the references made by a CPU to a frame buffer may not exhibit the spatial and temporal locality of normal program references. In particular, it is often the case that a long run of sequential frame buffer locations will be referenced, with each location being referenced exactly once. The result of this is that a direct mapped cache will become filled with display data, which will displace other cache information, including the data and program text of the program that modified the display image. This displacement will cause the number of cache misses to increase substantially, increasing the average access time seen by the CPU and lowering the system's performance.
The standard, prior art solution to the above problems is to operate frame buffers in an uncached portion of the system's address space. This means that such systems cannot take any advantage of the presence of a cache for the processing of frame buffer (i.e., image) data.
The present invention addresses each of the three problems listed above. By making modifications to the design of the cache and the frame buffer, it provides a design that supports frame buffers more effectively than previous arrangements.

Automatic writeback and storage limit in a high-performance frame buffer and cache memory system