Embodiments of the invention provide for automatically resolving computer system boot-up problems and for ensuring the reliability of boot-up. According to embodiments, a test of a condition of a computer system may be performed prior to attempting to load an operating system, to ensure the reliability of the system. In other embodiments, a boot-up may be attempted from a plurality of different operating system images, in the event a boot-up from a given operating system image fails.

The term "boot" or "boot up" is commonly used to describe loading operating system software into a computer system. More specifically, booting may comprise a process including several operations culminating in the loading of an operating system into system RAM. In many well-known systems, the boot process may begin with the loading of a BIOS (Basic Input/Output System) program from a ROM (Read-Only Memory) device. After performing some self-testing operations, the BIOS typically loads and then branches to a program called a "boot loader" that will actually load the operating system software. The boot loader typically resides in a reserved location on the system hard disk, for example, in the starting sectors of the hard disk.
After the BIOS program branches to the boot loader, the boot loader typically loads system initialization files that then proceed to load the operating system. Such initialization files may be known as "kernels" or operating system (OS) "images." A kernel or OS image may specify a basic configuration of the OS, such which OS files need to be loaded. For example, an OS image could specify which device drivers needed to be loaded.
As is well known, during a typical OS boot process, the process can "hang"; i.e., the process may stop short of a complete, successful boot due to some hardware or software problem, such as a corrupted or missing OS image. Typically, the first approach to addressing the problem of a boot that fails to complete successfully is to re-boot the system, usually from the same OS image.
In many settings, re-booting the system is performed by a human user; i.e., a user manipulates some control means of the computer, such as a keyboard or reset button, to cause the re-boot to be initiated. However, in other settings such human intervention is not readily available. For example, a computer in a remote base station of a telecommunications network may not be easily accessible by a user in the event that a boot of the computer hangs.
It is known to attempt to re-boot the system automatically (i.e., without human intervention). However, in known systems, the re-boot may be continually attempted from the same OS image. If the OS image is corrupted, for example, this can lead to an infinite loop of system resets, making the system unusable.
Additionally, known boot routines do not perform a rigorous test of the condition of the devices of the hardware platform in which an OS is to be loaded, prior to loading the OS. Examples of such devices include memory controllers, Ethernet cards, serial I/O cards and custom ASICs (Application Specific Integrated Circuits). Thus, an OS may appear to boot successfully, while in fact one or more devices of the hardware platform may not be operating or may be operating in a sub-standard condition. This can lead to problems later on, as the OS begins to run application programs that require the inoperative or sub-standard devices. The problems may be worsened, for example, in settings as discussed above, where there is no human operator available to monitor the computer and take corrective action if needed.
A method and system are needed to address the problems outlined in the foregoing discussion.

Method and system for improving computer system boot reliability by executing an application specific test during a boot prior loading an operating system


Instead of using a central site including spidering software to recursively search all linked web pages and generate a search index of the Internet, index cards files are created and stored on each web site to provide meta data in the form of conceptual or non-keyword information about the site, such as demographics and categorization information. The meta data is periodically collected and aggregated on a central server. A central catalog of object references is compiled on the central site from the meta data reported from each web site. The information from the index cards is utilized in constructing the central catalog so that more accurate search results may be generated for search queries applied to the catalog, so that the search results may be ranked in meaningful ways, and so that web sites may be more accurately rated.

In the last several years, the Internet has experienced exponential growth in the number of web sites and corresponding web pages contained on the Internet. Countless individuals and corporations have established web sites to market products, promote their firms, provide information on a specific topic, or merely provide access to the family's latest photographs for friends and relatives. As a result of the rapid growth in web sites on the Internet, it has become increasingly difficult to locate pertinent information.
Search engines, such as Inktomi, Excite, Lycos, Infoseek, or FAST, are typically utilized to locate information on the Internet. Upon inquiry from a user, the search engine software searches the millions of records contained in a central index. The search engine software finds matches to the search query and may rank them in terms of relevance according to predefined ranking algorithms. While most search engines accept submissions of sites for indexing, even upon such a submission, the site may not be indexed in a timely manner, if at all.
An inherent shortcoming of the method of indexing utilized in the conventional search engine is that only documents stored with a mark-up language such as SGML, HTML or XML is utilized in generating the central index. Due to the format of a mark-up language web page, certain types of information may not be placed in the mark-up language tags. For example, conceptual information such as the intended audience's demographics and geographic information may not be placed in an assigned tag in the document. Such information would be extremely helpful in generating a more useful index. For example, a person might want to search in a specific geographical area, or within a certain industry. Assume a person is searching for a red barn manufacturer in a specific geographic area. Because mark-up language pages have no standard tags for identifying industry type or geographical area, the spider on the server in the conventional search engine does not have such information to utilize in generating the central index. As a result, the conventional search engine would typically list not only manufacturers but would also list the location of picturesque red barns in New England that are of no interest to the searcher.
Some Internet search engines, such as Infoseek, have proposed a distributed search engine approach to assist their spidering programs in finding and indexing new web pages. Infoseek has proposed that each web site on the Internet create a local file named "robots1.txt" containing a list of all files on the web site that have been modified within the last twenty-four hours. Files that have not been modified will not be indexed, saving bandwidth on the Internet otherwise consumed by the spidering program and thus increasing the efficiency of the spidering program.
There is a need for a method and system of indexing or cataloging remotely stored data that allows conceptual information and other human generated information about web sites to be utilized in generating the index to allow sites to be found in a search, to make search results more meaningful, and to allow sites to be more accurately rated.
Full-text search and indexing systems such as web search engines typically have two distinct means of organizing the presentation of documents. The first means is usually a categorization system (hierarchical or otherwise) which presents the documents in groups or "clusters" related by topic, content or origin. The second is dynamically generated as a result of a search process of some sort such as a matching keyword search. Normally, this second means is presented as a linear list in which matching documents are sorted either by alphabetical title, date of change or a ranking value based on a calculation whose input may come in part from the document content. For example, in searching for the work "car" in a set of documents, the resulting list of matching documents might be sorted by the number of times the word occurred in each document.

Index cards on network hosts for searching, rating, and ranking


An apparatus is disclosed for monitoring brushes, such as slipring or commutator brushes, on electrical machines. At least one electronic sensor is configured to be arranged in or on a brush apparatus of an electrical machine such that an electrical supply power can be locally drawn directly from an electromagnetic environment of the brush apparatus. The apparatus can transmit measurement data detected by it by electromagnetic radiation to an indication device.

Large electrical generators or motors can include sliprings or commutators and associated brushes, via which the field current or drive current is supplied. These brushes can be manufactured from carbon and graphite materials and are subject to relatively high wear. For smooth operation of an electrical machine with brushes such as these, it is desirable to monitor the brushes, in particular the brush wear, as continuously as possible.
U.S. Pat. Nos. 4,950,933 and 4,739,208 have disclosed apparatuses in order to monitor the length of slipring brushes for a predetermined minimum value. When the predetermined minimum value is undershot, this mechanically or magnetically initiates a closing or opening process of an electrical contact. The closing or opening of the electrical contact is detected, and is indicated by a signal. It is therefore possible to determine, in the form of a length statement, whether the brushes have or have not undershot the length limit value.
U.S. Pat. No. 5,870,026 discloses an apparatus by which the instantaneous, still remaining length of a brush can be output as an analog value. For this purpose, a resistance element is embedded in the brush and is shortened as it wears away. The resistance, which changes as it wears away, is used as a measure of the length of the brush.
However, in these known apparatuses, in some cases, only a local indication of the fault state, that is to say of a worn-out brush, is provided. Since the brush apparatuses of electrical machines can be in a closed form, this indication can easily be overlooked, or cannot be monitored so easily by maintenance personnel.
In some cases, remote indication is admittedly also made possible, although electrical signal connections are then used for this purpose via cables from the outside to the brush apparatus. Because of the generally high electrical voltage and the high potential energies which exist in electrical machines, for example in the case of an electrical generator, when in the energized state, this results, however, in a major potential danger. Measures to cope with this potential change are generally quite complex.

Apparatus for monitoring of brushes, in particular slipring or commutator brushes, on electrical machines


In a cutting tool rotatable about a tool axis, a reversible cutting insert is removably secured in a tool body. The cutting insert has opposing top and bottom end surfaces interconnected by a peripheral surface, and a median plane located therebetween. The peripheral surface includes four side surfaces alternating with four corner surfaces, the side and corner surfaces intersecting the top surface to form top major cutting edges and top corner cutting edges, respectively. Each side surface has a median surface and a top major relief surface. Each top major relief surface forms an acute internal top major relief angle with the median plane, and the median plane intersects the four median surfaces to define an imaginary median square. In a top end view of the cutting insert, the four top major cutting edges define an imaginary top major square rotationally offset from the imaginary median square.

Within the field of rotatable cutting tools used in milling operations, there are many examples of reversible cutting inserts being removably secured in a cutting body. In some instances, the cutting inserts are square-shaped inserts.
U.S. Pat. No. 7,604,441 discloses a fully indexable square cutting insert having four side surfaces connecting to two end surfaces. At the intersection of each side surface with an end surface is a primary cutting edge which extends from an insert corner and along a first side surface, in a downward direction towards a median plane. A wiper extends from the same insert corner and along an adjacent side surface, in an upward direction away from the median plane, to rise above an abutment surface of an associated end surface. The geometry of the cutting insert and of the insert pocket in which the insert is seated are such that the primary cutting edge has a positive axial angle (helix), while the insert has an overall negative axial angle for providing axial clearance and an overall negative radial angle for providing radial clearance.
U.S. Pat. No. 8,491,234 discloses a double-sided cutting insert with a plurality of indexable convex cutting edges. The cutting insert has a top face and a bottom face, at least three convex cutting edges on each face connected by at least three nose corners, at least three peripheral side surfaces extending from each face toward a virtual middle plane; and a common lateral seating surface on each peripheral side surface. Each convex cutting edge has at least a curved cutting edge region, and further has a primary substantially straight cutting edge region intermediate the curved cutting edge region and the nose corner. Each peripheral side surface further has a primary planar facet associated with the primary substantially straight cutting edge, and each face is single-handed in same direction. Additionally, in various embodiments, the top and bottom faces of the cutting insert may be formed such that they are twisted or rotated with respect to each other.
U.S. Pat. No. 8,641,331 discloses a milling cutting insert having a square or triangular shaped cutting face delimited in the plan view by a peripheral cutting edge having linear cutting edges and curved cutting corners. Each of the cutting edges comprises an inclined region sloping toward a cutting corner, extending beyond the tangential point determined by the point at which the linear cutting edge transitions into a curved cutting corner, wherein adjacent thereto the cutting edge rises prior to the point determined by a cutting corner angle bisector, wherein said rising region extends to a cutting edge maximum on the other side of the cutting corner on the adjacent cutting edge, which is linear in plan view, from where the cutting edge continues, again inclined and sloping downward, resulting in a rotationally symmetric form having identically shaped cutting edges.
U.S. Pat. No. 9,724,770 discloses a double-sided cutting insert for milling which having eight main cutting edges and eight wiper edges. The cutting insert includes top and bottom faces and four side faces. Each side face includes first and second sub-faces inclined with respect to each other. The first sub-face has a main cutting edge adjacent to the top face and a wiper edge adjacent to the bottom face. The second sub-face has a wiper edge adjacent to the top face and a main cutting edge adjacent to the bottom face. The wiper edge of the second sub-face is inclined inwardly relative to the cutting insert with respect to the main cutting edge of the first sub-face. The wiper edge of the first sub-face is inclined inwardly relative to the cutting insert with respect to the main cutting edge of the second sub-face.
It is an object of the present invention to provide an improved reversible cutting insert having four major cutting edges per end surface.
It is also an object of the present invention to provide an improved reversible cutting insert having robust cutting edges.
It is a further object of the present invention to provide an improved rotatable cutting tool in which the cutting insert is removably secured in a tool body with a high level of stability.
It is still a further object of the present invention to provide an improved rotatable cutting tool in which an increased number of cutting inserts are circumferentially spaced around the tool body.
It is yet still a further object of the present invention to provide an improved rotatable cutting tool capable of performing square shoulder milling operations.

Reversible square-shaped cutting insert and rotary cutting tool


A quick-release magazine for use with firearms is provided, the magazine comprising a conventional firearm magazine and a spring, the spring comprising a center plate with two fins projecting outwardly from the plate. The spring is positioned between the floor plate and base pad of the magazine, with the center plate of the spring aligning with the magazine and the fins projecting outwardly from the plate. When the magazine of the present invention is inserted into a firearm, the fins are compressed between the magazine and the gun. The compressed fins provide a forceful ejection from the firearm when the magazine must be replaced.

Firearms, including pistols, rifles and shotguns, are used in a variety of sporting competitions around the country wherein various skills of the competitor are matched against both another opponent and the clock. Similarly, firearms are a staple piece of equipment for hunters, law enforcement and military personnel, worldwide. Key to success in competition, in the field, and on the battlefield is the ability to handle and fire a firearm quickly and skillfully. Thus, the number of rounds of ammunition any particular weapon can fire before it needs to be reloaded is of significant interest. Further, in certain competitive events, as well as in law enforcement and military applications, the ability to reload a weapon quickly and accurately is a prized quality.
Weapon designers constantly strive to decrease the time needed to reload a firearm. It is axiomatic that a competitor (or soldier) who spends less time reloading his weapon will have an advantage over a similarly situated competitor (or enemy soldier) who spends more time reloading his weapon. With regard to military and law enforcement applications, the advantages of a quick-release magazine are obvious. The faster an empty magazine can be released and a fully-loaded magazine inserted into the weapon, the faster a soldier or police officer can protect himself or another.
In many types of automatic, semi-automatic, bolt-action, and lever-action firearms (e.g., pistols, rifles, shotguns, and the like), several rounds of ammunition (anywhere from two to several hundred or more) are stored in a spring-loaded magazine. While the physical dimensions of magazines differ among manufacturers, models and calibers, all firearm magazines share certain critical features. Notably, all magazines include a housing in which the rounds are stored and held until needed. The housing includes an open top which is dimensioned and configured to feed the rounds of ammunition smoothly into the receiver of the corresponding firearm. The outer dimensions of the housing are configured to matingly and releasably engage a corresponding magazine bay and magazine locking/releasing mechanism of a corresponding firearm. Disposed inside the housing, and anchored at the bottom of the magazine, is spring that is biased to urge the rounds of ammunition toward the top of the magazine. In this fashion, as the top-most round in the magazine is extracted and fired (by the action of the firearm), a new round is urged into the top-most position and is ready to be loaded into the receiver of the firearm. Small-capacity magazines for most pistols and center-fire rifles are roughly rectangular in appearance, while large-capacity magazines are normally curved to save space. Certain types of long guns, such as many rimfire .22 caliber rifles, use tubular magazines that feed the rounds axially, rather than transversely. As used herein, the term "magazine" encompasses all such magazines, without limitation.
In pistols and certain types of carbines (short-barreled rifles), the magazine bay is located in the pistol grip of the firearm. In most hunting long guns, the magazine bay is located forward of the trigger assembly, in or near the "forearm" area of the weapon. In certain tactical military weapons, the magazine is located behind the trigger assembly in the butt of the weapon. (This type of firearm is often called a "bullpup," a design that yields a very compact weapon.) Firearms with a tubular magazine can have the magazine disposed within either the butt of the weapon or in the forearm of the weapon.
The Colt model M1911 pistol and its magazine are a perfect example of a typical semi-automatic pistol design. The model M1911 pistol remains a very popular and widely copied semi-automatic pistol. This storied pistol was designed by John M. Browning and was the standard-issue sidearm for U.S. military forces from 1911 until 1985 (hence the designation "M" for military and the first year of its mass production). The Colt M1911 was originally chambered in .45 ACP. The design proved an instant success. Roughly 2.7 million M1911s were produced by the close of World War I. In the period between the world wars, the design was modified slightly and the modified version was given the model designation 1911A1. During this period, more than 20 different manufacturers, worldwide, were licensed to produce this model, in a wide range of different calibers. U.S. manufacturers, including Colt, Remington, Ithaca, Union Switch and Signal, and The Singer Sewing Machine Company, combined to produce more than 2 million model 1911A1 pistols in the war years 1941 to 1945. The 1911 design, long since "off-patent", has been widely copied and modified.
The magazine for a 1911-style pistol features a roughly rectangular housing with walls that narrow in width at the top. The bottom of the housing is open and terminates in an outwardly-directed lip or flange. A floor plate is attached to the flange at the lower end of the housing, thereby closing off the bottom end of the magazine. A butt pad or "slam pad" is also attached to the flange at the lower end of the housing, and serves to cushion the lower end of the housing when the magazine is forcefully inserted into the firearm (which is often the case). A leaf spring is disposed within the lower end of the housing to urge the rounds loaded within the magazine toward the top. When the magazine is empty, a release button on the pistol is pressed, and the magazine is grasped at its lower end by the user's free hand and separated from the weapon.
The prior art is replete with efforts to decrease the time needed for reloading. The most simple route, of course, is to increase the capacity of the magazine (while conforming to the law and the standards of any given competition). Many countries, however, place strict limits on magazine capacities for firearms sold into the civilian markets. After-market, large-capacity magazines are widely available in the United States. But a larger magazine also significantly increases the weight of the weapon when the magazine is fully loaded. The added weight of additional rounds compromises the speed of handling the weapon and the added weight can also compromise the accuracy of the weapon. Large capacity magazines also tend to misfeed more often than smaller capacity magazines. Thus, a larger capacity is not an ideal solution to minimizing the time needed to reload a firearm.


A connector for fluidly coupling proximal and distal tubular segments of a fluid conduit is provided. In one embodiment, the connector can include a connector body having an outer surface defining a first outer perimeter and an inner surface defining a lumen. The connector can also include a connecting device having an open configuration and a plurality of closed configurations. The connecting device can include first and second members configured to engage each other to secure the fluid conduit to the connector. The connecting device can also include a plurality of closed configurations for securing fluid conduits of different sizes.

This application relates to a connector which can be included in a system for connecting multiple portions of a fluid carrying conduit.
In the United States, approximately 400,000 people have end-stage renal disease requiring chronic hemodialysis. Permanent vascular access sites for performing hemodialysis may be formed by creating an arteriovenous (AV) anastomosis whereby a vein is attached to an artery to form a high-flow shunt or fistula. A vein may be directly attached to an artery, but it may take 6 to 8 weeks before the venous section of the fistula has sufficiently matured to provide adequate blood flow for use with hemodialysis. Moreover, a direct anastomosis may not be feasible in all patients due to anatomical considerations.
Other patients may require the use of artificial graft material to provide an access site between the arterial and venous vascular systems. Patency rates of grafts are still not satisfactory, as the overall graft failure rate remains high. Temporary catheter access is also an option. However, the use of temporary catheter access exposes the patient to additional risk of bleeding and infection, as well as discomfort.


Multi-type air conditioner comprising an outdoor unit installed in an outdoor, comprising a compressor, a refrigerant flow controlling part connected to a discharge end of the compressor for guiding the refrigerant proper to operation conditions selectively, an outdoor heat exchanger connected to the refrigerant flow controlling part, a defrosting device at a side of the outdoor heat exchanger, and a piping system connected between the parts, a plurality of indoor units each installed in a room and having an indoor heat exchanger and an electronic expansion valve having one end connected to one end of the indoor heat exchanger, and a distributor between the outdoor unit and the indoor units for selectively guiding refrigerant from the outdoor unit to the plurality of indoor units proper to operation conditions, and guiding the refrigerant passed through the indoor units to the outdoor unit again.

1. Field of the Invention
The present invention relates to multi-type air conditioners, and more particularly, to a defrosting device for removal of frost formed during heating operation from an outdoor heat exchanger, and a multi-type air conditioner with the defrosting device.
2. Background of the Related Art
In general, the air conditioner, an appliance for cooling or heating room spaces, such as living spaces, restaurants, and offices, cools or heats the room space by circulating refrigerant with a compressor and heat exchangers.
The air conditioner succeeds to development of a multi-type air conditioner which can cool or heat rooms at the same time without being influenced from an external temperature or environment for maintaining more comfortable room environments, resulting to cool or heat entire rooms under the same operation mode.
A related art multi-type air conditioner is provided with one or more than one outdoor unit connected to a plurality of indoor units installed in respective rooms, and operative only in one mode of cooling or heating for controlling room temperatures.
However, nowadays, as the room space becomes larger, a room structure becomes complex, and positions and services of rooms are diversified, room environments of the rooms differ from one another. Particularly, a room equipped with machinery or computer has a room temperature higher than other rooms due to heat from operation of the equipment.
Consequently, as some of the rooms require cooling, while other rooms require heating, the related art multi-type air conditioner can not deal with.
Moreover, in a case the multi-type air conditioner is operated in a heating mode, frost is formed on the outdoor heat exchanger in the outdoor unit caused by cooled down environmental air, which drops an air conditioning efficiency of the air conditioner. Since it is required to shift to the operation mode to cooling for removing the frost from the outdoor heat exchanger, no heating is available during a defrosting operation.
According to above requirement, development of a multi-type air conditioner of concurrent cooling and heating type is required.
For improving the air conditioning efficiency of the air conditioner, development of a multi-type air conditioner with a defrosting device for removal of frost formed during heating operation from the outdoor heat exchanger.

Multi-type air conditioner with defrosting device


Thermal pole tip protrusion is caused by materials in and around head slider expanding during write operations till they protrude, leading to contact with the rotating disk surface, altering the flying height and often wearing down part of the disk surface. While well known that read-write heads expand during writing, the inventors who recognized this situation's significance, particularly as flying height decreases and data rates increase, both required for high areal density disk drives. The inventors realized that they could detect the problem at the spin stand level by testing head gimbal assemblies to reliably, and inexpensively, predict the tendency for thermal pole tip protrusion. This leads to selection of head gimbal assemblies, which do not have the thermal pole tip protrusion tendency. The selected head gimbal assemblies have better reliability, as do actuators and disk drives made with the selected head gimbal assemblies.

Disk drives are an important data storage technology. Read-write heads are one of the crucial components of a disk drive, directly communicating with a disk surface containing the data storage medium. Read-write heads generate heat during write operations due to the large currents required for that operation. The inventors have discovered quality problems associated with thermal expansion, causing tip protrusion. A review of the relevant background will be made before discussing their discovery of the problem and their solutions.
FIG. 1A illustrates a typical prior art high capacity disk drive 10 including actuator arm 30 with voice coil 32, actuator axis 40, head arms 50–58 with head suspension assembly 60 placed among the disks.
FIG. 1B illustrates a typical prior art high capacity disk drive 10 with actuator 20 including actuator arm 30 with voice coil 32, actuator axis 40, head arms 50–56 and head suspension assemblies 60–66 with the disks removed.
FIG. 2A illustrates a head gimbal assembly including head suspension assembly 60 with head slider 100 containing the read-write head 200 of the prior art.
Since the 1980's, high capacity disk drives 10 have used voice coil actuators 20–66 to position their read-write heads over specific tracks. The heads are mounted on head sliders 100, which float a small distance off the disk drive surface when in operation. The flotation process is referred to as an air bearing. The air bearing is formed by the read-write heads 200, illustrated in FIG. 2A, and head slider 100, as illustrated in FIGS. 1A–2A. The flying height of the air bearing is very small, often about 100 Angstroms, or about 0.4 millionths of an inch, which is far smaller than a human hair.
Often there is one head per head slider for a given disk drive surface. There are usually multiple heads in a single disk drive, but for economic reasons, usually only one voice coil actuator.
Voice coil actuators are further composed of a fixed magnet actuator 20 interacting with a time varying electromagnetic field induced by voice coil 32 to provide a lever action via actuator axis 40. The lever action acts to move head gimbal assemblies 50-56, positioning head suspension assemblies 60-66, and their associated head sliders 100 containing read-write heads 200, over specific tracks with speed and accuracy. Actuator arms 30 are often considered to include voice coil 32, actuator axis 40, head gimbal assemblies 50–56 and head suspensions 60–66. An actuator arm 30 may have as few as a single head gimbal assembly 50. A single head gimbal assembly 52 may connect with two head suspensions 62 and 64, each with at least one head slider.
FIG. 2B illustrates the relationship between the principal axis 110 of an actuator arm 50 containing suspension 60, which in turn contains head slider 100, as found in the prior art.
FIG. 2C illustrates a simplified schematic of a disk drive controller 1000 of the prior art, which may be used to control a spin stand test unit.
Disk drive controller 1000 controls an analog read-write interface 220 communicating resistivity found in the spin valve within read-write head 200. Disk drive controller 1000 concurrently controls servo-controller 240 driving voice coil 32, of the voice coil actuator, to position read-write head 200 to access a rotating magnetic disk surface 12 of the prior art.
Analog read-write interface 220 frequently includes a channel interface 222 communicating with pre-amplifier 224. Channel interface 222 receives commands, from embedded disk controller 100, setting at least the read_bias and write_bias.
Various disk drive analog read-write interfaces 220 may employ either a read current bias or a read voltage bias. By way of example, the resistance of the read head is determined by measuring the voltage drop (V_rd) across the read differential signal pair (r+ and r−) based upon the read bias current setting read_bias, using Ohm's Law.
FIG. 2D illustrates a detailed view head suspension 60 of the prior art.
A prior art head suspension 60 includes suspension load beam 80 mechanically coupled via hinge 82 with extended base plate 84. Head suspension 60 further includes flexure 86, providing electrical interconnections of the read and write differential signal pairs 210, between the disk drive analog interface 220 and read-write head 200 (both in FIG. 2C).
The head gimbal assembly includes head slider 100 rigidly mounted on head suspension 60, with read-write head 200 electrically connected to flexure 86. Head slider 100 is mounted over the right portion of suspension load beam 80 so that read-write head 200 makes contact with flexure 86.
The hinge 82 includes a spring mechanism. Suspension load beam 80, hinge 82 and extended base plate 84 are all typically made from stainless steel. Flexure 86 is a flex printed circuit typically made using polyamide and copper traces.
What is needed are reliable head gimbal assemblies and actuators, which will minimize read-write head crashes by reliably maintaining the flying height, even as the flying height decreases and the data rates increase, to insure the quality of the disk drives in which they are used. The inventors know of no known discussion of the relationship between thermal pole tip protrusion to reliably maintaining the flying height.

Method of estimating a thermal pole tip protrusion for a head gimbal assembly


A light source unit, a light receiving unit that includes a distance image sensor in which a plurality of pixels each including a photoelectric conversion device generating electric charge corresponding to incident light and a plurality of electric charge accumulating units accumulating the electric charge and dividing and accumulating the electric charge among the electric charge accumulating units at a predetermined accumulation timing are arranged in a two-dimensional matrix pattern, a distance image processing unit that is configured to acquire a distance from a subject present in the space that is an imaging target, and a timing determining unit that is configured to determine the accumulation timing in the measurement time interval on the basis of an electric charge amount in each of the electric charge accumulating units in an inspection time interval in which the light pulse is not emitted at the accumulation timing are provided.

Conventionally, distance sensors of a time of flight (hereinafter referred to as "TOF") system measuring a distance from a subject that is a target object on the basis of a flight time of light using the fact that the speed of light is known have been realized. In a distance sensor of the TOF system, near-infrared light is emitted to a space of an imaging target, and a distance from a subject is measured on the basis of a difference between a time at which the near-infrared light is emitted and a time at which the near-infrared light is reflected by a subject and returns, in other words, a flight time of the near-infrared light.
In addition, among the recent TOF system based distance sensor, similar to a solid-state imaging device mounted in an image capturing device, a so-called distance image capturing device, in which a plurality of pixels detecting light used for measuring a distance are disposed in a two-dimensional matrix pattern, capable of acquiring (capturing) not only information of a two-dimensional distance from a subject but also an image of the subject has also been realized.
In a distance image capturing device, there is a system employing a configuration in which near-infrared light having a pulse shape (hereinafter referred to as a "light pulse") is emitted, and a flight time of the light pulse is measured on the basis of a difference between a time at which the light pulse is emitted and a time at which the light pulse reflected by a subject is detected after a predetermined time among a plurality of systems for measuring a distance from a subject. In a distance image capturing device of such a system, there is an imaging device used as a sensor for acquiring information of a distance from a subject and an image of the subject having a configuration in which a plurality of electric charge accumulating parts and a constituent element dividing electric charge among the electric charge accumulating parts are disposed within each pixel. In an imaging device having such a divisional configuration, a distance from a subject can be measured by dividing electric charge generated by a photoelectric conversion device configuring a pixel among electric charge accumulating parts and calculating a delay time of a light pulse that arrives after being reflected by the subject on the basis of a ratio of electric charge divided among the electric charge accumulating units.
It is necessary for a distance image capturing device to measure a distance in various situations and environments of a subject. For example, there is a situation in which a plurality of distance image capturing devices are adjacently present, or there is an environment in which a subject that is a target for which a distance is measured by being surrounded by a plurality of distance image capturing devices. In such a situation or environment, direct light or reflective light of a light pulse emitted by another distance image capturing device may be mixed in the reflective light of a light pulse emitted by a certain distance image capturing device. In such a case, a situation in which a light pulse emitted by another distance image capturing device is erroneously recognized as a light pulse reflected by a subject, and accuracy of measurement of a distance from a subject will decrease or a distance from a subject cannot be measured is conceivable. For this reason, in an environment in which a light pulse emitted from another distance image capturing device is incident, in order for a distance image capturing device to measure a distance from a subject, it is preferable to reduce the influence of the light pulse emitted from the other distance image capturing device.
In relation to this, for example, as disclosed in Patent Document 1, a technology relating to a distance sensor (distance image capturing device) has been proposed. The distance sensor disclosed in Patent Document 1 includes a period setting unit that is configured to change the length of an accumulation period such that a total time interval of accumulation periods corresponding to a predetermined number of times deviates by one accumulation period or more before and after the change in the length of the accumulation period. Here, the accumulation period is a period in which a light receiving unit accumulates the amount of received light in accordance with the emission of light using a light source unit. In other words, in the technology of the distance sensor disclosed in Patent Document 1, the length of the accumulation period is changed. In this way, in the distance sensor disclosed in Patent Document 1, in a time interval of the accumulation period, while incidence of interference light (a light pulse emitted from another distance sensor) is allowed, the influence of interference light included in electric charge divided among the electric charge accumulating units is statistically uniformized, whereby erroneous measurement of a distance according to the incidence of interference light can be inhibited.

Distance image capturing device, distance image capturing system, and distance image capturing method


A switch to switch protocol for network load balancing which exchanges cost information among all switches in a load balance domain. As compared to prior techniques, the protocol of the present invention updates all switches in the load balance domain periodically. All switches in the load balance domain are thereby assured of having consistent cost information regarding all switches in the load balance domain. Further, the protocol of the present invention reduces the volume of cost messaging traffic as exemplified by techniques which generate updates to the information any time a cost parameter of a switch changed. The preferred embodiment of he protocol of the present invention exchanges messages describing the switch latency for each switch in the load balance domain. A bit mask field in the transmitted cost packets indicates which switches have already received the cost information. Receipt of the same packet a second time by a switch which already received the cost packet is indicative of a loop in the network and the propagation of that packet is terminated.

1. Field of the Invention
The present invention relates to communication networks and more specifically to network switches and associated switch to switch protocols which provide improved bandwidth utilization and load balancing in data processing communication networks having redundant paths between network devices.
2. Related Patents
This patent is related to the following commonly owned patents: U.S. patent Ser. No. 09/228,110 entitled Load Balancing Switch Protocols, U.S. patent Ser. No. 09/228,159 entitled Identity Negotiation Switch Protocols, U.S. patent Ser. No. 09/228,913 entitled Cost Calculation in Load Balancing Switch Protocols, U.S. patent Ser. No. 09/228,087 entitled Broadcast Tree Determination in Load Balancing Switch Protocols, U.S. patent Ser. No. 09/228,918 entitled MAC Address Learning and Propagation in Load Balancing Switch Protocols, U.S. patent Ser. No. 09/228,992 entitled Path Recovery on Failure in Load Balancing Switch Protocols, and U.S. patent Ser. No. 09/228,169 entitled Discovery of Unknown MAC Addresses Using Load Balancing Switch Protocols, all of which are hereby incorporated by reference.
3. Discussion of Related Art
It is common in present computing environments to connect a plurality of computing systems and devices through a communication medium often referred to as a network. Such networks among communicating devices permit devices (or users of devices) to easily exchange and share information among the various devices. The Internet is a presently popular example of such networking on a global scale. Individual users attach their computers to the Internet, thereby enabling sharing of vast quantities of data on other computers geographically dispersed throughout the world.
Networked computing systems may be configured and graphically depicted in a wide variety of common topologies. In other words, the particular configurations of network communication links (also referred to as paths) and devices between a particular pair of devices wishing to exchange information may be widely varied. Any particular connection between two computers attached to a network may be direct or may pass through a large number of intermediate devices in the network. In addition, there may be a plurality of alternative paths through the network connecting any two network devices. Present day computing networks are therefore complex and vary in their configurations and topologies.
Most present network communication media and protocols are referred to as packet oriented. A protocol or communication medium may be said to be packet oriented in that information to be exchanged over the network is broken into discrete sized packets of information. A block of information to be transferred over the network is decomposed into one or more packets for purposes of transmission over the network. At the receiving end of the network transmission, the packets are re-assembled into the original block of data.
In general, each packet includes embedded control and addressing information that identifies the source device which originated the transmission of the packet and which identifies the destination device to which the packet is transmitted. Identification of source and destination devices is by means of an address associated with each device. An address is an identifier which is unique within the particular computing network to identify each device associated with the network. Such addresses may be unique to only a particular network environment (i.e., a network used to interconnect a single, self-contained computing environment) or may be generated and assigned to devices so as to be globally unique in co-operation with networking standards organizations.
At the lowest level of network communication, such addresses are often referred to as MAC address (Media ACcess address). Network protocols operable above this lowest level of communication may use other addresses for other purposes in the higher level communication techniques. But in most network low level communication levels, operable on the physical link medium, an address is referred to as a MAC address.
In many present commercially available network environments, the network communication medium is in essence a bus commonly attached to a plurality of devices over which the devices exchange. In a simple networking topology, all devices may be attached to a such a bus structured common network medium. Any particular single network medium has a maximum data exchange bandwidth associated therewith. The maximum data exchange bandwidth of a medium is determined by a number of electrical and physical properties of the medium and protocols used to communicate over that medium. For example, a popular family of related network media and protocols are collectively referred to as Ethernet. Ethernet defines a standard protocol for the exchange of messages over the communication medium. A variety of communication media are also defined as part of the Ethernet family. The communication bandwidth of the Ethernet family of standards range from approximately 10 Mbit (million bits of information) per second to 1 Gbit per second. Therefore, a single (slow) Ethernet connection, for example, has a maximum data exchange bandwidth of approximately 10 Mbit per second.
In present network computing environments, a number of devices are used in addition to interconnected computing systems to efficiently transfer data over the network. Routers and switches are in general network devices which segregate information flows over various segments of a computer network. A segment, as used herein, is any subset of the network computing environment including devices and their respective interconnecting communication links. As noted above, a single computer network communication link has a maximum data transfer bandwidth parameter defining the maximum rate of information exchange over that network. Where all devices on a computer network share a common network medium, the maximum bandwidth of the computer network may be rapidly reached. The overall performance of the networked computing environment may be thereby reduced because information exchange requests may have to await completion of earlier information exchange requests presently utilizing the communication link.
It is often the case, however, that particular subsets of devices attached to the network have requirements for voluminous communication among members of the same subset but less of a requirement for information exchange with other devices outside their own subset. Though standard switch features generally do not include identifying such logical groupings of devices, some enhanced switching features do permit such logic to be performed within a switch device. For example, some enhanced switch features include the concept of defining and routing information based on virtual LAN (VLAN) definitions. In a VLAN, a group of devices may be defined as logically being isolated on a separate network although physically they are connected to a larger network of devices. VLAN features of enhanced switches are capable of recognizing such VLAN information and can route information appropriately so that devices in a particular VLAN are logically segregated from devices outside the VLAN.
For example, the financial department of a large corporation may have significant information exchange requirements within the financial department but comparatively insignificant needs for data exchange with other departments. Likewise, an engineering group may have significant needs for data exchange within members (computing systems and devices) of the same engineering group but not outside the engineering group. There may in fact be multiple of such subsets of devices in a typical computing network. It is therefore desirable to segregate such subsets of devices from one another so as to reduce the volume of information exchange applied to the various segments of the computer network.
In particular, a switch device is a device that filters out packets on the network destined for devices outside a defined subset (segment) and forwards information directed between computing devices on different segments of a networked computing environment. The filtering and forwarding of such information is based on configuration information within the switch that describes the data packets to be filtered and forwarded in terms of source and/or destination address information (once address locations are xe2x80x9clearnedxe2x80x9d by the switch(es)).
Network switch devices and protocols associated therewith are also used to manage redundant paths between network devices. Where there is but a single path connecting two network devices, that single path, including all intermediate devices between the source and destination devices, represent a single point of failure in network communications between that source and destination device. It is therefore common in network computing environments to utilize a plurality of redundant paths to enhance reliability of the network. Multiple paths between two devices enhances reliability of network communication between the devices by allowing for a redundant (backup) network path to be used between two devices when a primary path fails.
FIG. 1 shows an exemplary, simple networked computing environment in which multiple paths exist for communication between devices A 100, B 102, and C 104. These exemplary network devices are each attached to one of a plurality of switches (S1106, S2108, S3110, and S4112). Each device has multiple possible paths to each of the other two devices. For example, device A 100 may exchange information with device C 104 through any of three possible paths (via switches S1106 and S4112, respectively). The first exemplary path is a direct path connecting device A 100 directly to device C 104 through a port on switch S1106 and a port on switch S4112. A second path is through switch S1106 to switch S3110 and then through switch S4112. A third path is via switch S1106, switch S2108, and switch S4114. These three paths may be used as redundant communication paths connecting the two devices A 100 and C 104. Where a first path fails, the second path or third may be activated to assume responsibility for exchange of information between devices A and C. In like manner, there are three paths for communication between devices A 100 and B 102 and between devices B 102 and C 104.
Where redundant paths are available in such network computing environments, it remains a problem to effectively utilize the full available bandwidth. It would be desirable to utilize all redundant paths in parallel so as to increase the available communication bandwidth between two communicating devices. Where only a single path is used, the maximum bandwidth for exchange of information is limited to that of a single communication link. Where, on the other hand, all redundant links are used in parallel, the maximum communication bandwidth is increased by the number of links used in parallel. For example, as shown in FIG. 1, the communication bandwidth between any of the devices could, in theory, be increased by up to a factor of three.
However, as presently practiced in the art, protocols used among switch devices (e.g., S1106 through S4112) render such parallel communication paths unusable. Switches 105 through 112 as presently practiced in the art often use a protocol commonly referred to as xe2x80x9cspanning treexe2x80x9d to discover the existence of redundant communication paths as known to a network of switches. The spanning tree protocol is described in detail in a proposed IEEE standard P802.1p entitled Standard for Local and Metropolitan Area Networks Supplement to Media Access Control (MAC) Bridges: Traffic Class Expediting and Dynamic Multicast Filtering.
The spanning tree protocol as implemented in switches broadcasts (more precisely multicasts) information from the switch out to all devices that recognize the selected multicast address connected to paths from the switch. A multicast message is one which is directed to all devices rather than to a particular destination address on the network. The information in the multicast message describes the address forwarding information known to that switch. From such information shared among all the switches, each switch can derive the various paths in the network. Each switch device so attached to the multicasting device receives the information and forwards (multicasts) the message to each device attached to it (except the path from which it directly received the message), and so on. If such a multicast message returns on a path to the originating device, a loop must exist among the paths connecting the various switches. To reduce the number of messages generated on the network by virtue of such multicast messages, the spanning tree protocol requires that redundant paths so discovered be disabled. In a large network without spanning tree protocol to disable redundant paths, received multicast messages can xe2x80x9ccascadexe2x80x9d from each receiving switch to all other attached switches. The volume of such cascading messages may grow rapidly or even exponentially. Such multicast messages exchanged among the switched may in fact require a substantial portion of the available communication bandwidth of the network. Such conditions are often referred to as xe2x80x9cbroadcast storms.xe2x80x9d
The spanning tree protocol therefore requires the disabling of redundant paths to avoid broadcast storms. Only when a path is known to have failed will a redundant path be enabled and used for the exchange of data. The spanning tree protocol therefore precludes aggregation of the available bandwidth to improve communication bandwidth by using multiple redundant paths in parallel. FIG. 2 is a block diagram of the same exemplary network of FIG. 1 where three communication links 114 between the switches have been disabled to prevent loops in the network and the resultant broadcast storm otherwise inherent in the spanning tree protocol.
Another problem with the spanning tree protocol arises from the fact that a preferred path may be unavailable due to the need to disable paths that cause loops among the switches. For example, as shown in FIG. 2, the preferred path between switches S1106 and S4112 may be the direct one which is disabled. To leave this direct communication link enabled would permit loops in the paths among the switches. Rather, a more circuitous route through switches S1, 106, S3110 and S4112 must be used to exchange information between switches S1106 and S4112. The spanning tree protocol does not assure that the best path between two switches will be left enabled. Rather, it merely attempts to assure that some path between switches is available, specifically, a relatively minimal path connecting all switchesxe2x80x94a spanning tree.
The spanning tree protocol therefore precludes maximizing use of available bandwidth in a network of switches.
Some switches have provided a partial solution to this problem by using a technique known as xe2x80x9ctrunking.xe2x80x9d Where there are multiple paths directly between two switches, the multiple paths serve as redundant communication paths but are trunked by the switches and treated logically as though they were a single path with higher maximum bandwidth. FIG. 3 is a block diagram of the same exemplary network environment of FIG. 2 wherein a plurality of communication paths between switch S1106 and S3110 are trunked. The communication path between switches S1106 and S3110 is therefore capable of using the trunked paths between them as though they were a single connection in terms of the spanning tree protocols. Since the redundant paths are treated as a single path for purposes of the spanning tree protocols, they need not be shut down to preclude broadcast storms.
However, trunking does not address the bandwidth issue in a broad sense. Rather, the trunking technique is only applicable where the multiple paths are between a particular pair of switches. The bandwidth limit is merely shifted from that of a single communication link to that of the number of communication links supported by a single switch.
It is a further problem that by precluding use of redundant links between switches, the spanning tree protocol also precludes the ability to balance communication loads among the redundant paths between switches. Where such multiple paths are allowed to simultaneously operate, it would be desirable for the switches to distribute the packet exchange communication among them over such multiple paths. Such distribution, often referred to as load balancing, further enhances the ability of the network to optimize the utilization of available throughput in the network of switches. Underutilized paths may be used to offload packet communication on overloaded paths.
It is therefore a problem in present networks of switches to simultaneously operate redundant paths between switches of the network to thereby maximize utilization of available bandwidth and to thereby communicate among the switches to balance communication loads over redundant paths.
It is a particular problem to efficiently propagate cost information associated with each link between switches of the network. As presently practiced in the art, cost information is propagated whenever there is a change in cost values associated with a link or switch in the network. The nature of many net applications tends to have bursts of network traffic as particular users or applications start and stop their receptive activities. These bursts represent potential significant changes in the loads among various switches in a network. It is therefore a problem to rapidly adapt the bandwidth utilization of a network of switches to balance the load of network packet exchange over a plurality of redundant paths.
This cost information is used by switches of the network to determine preferred or optimal paths between the switches for further exchange of packets. Optimal paths may vary depending upon the operation status of switches in the network. If a switch or link is temporarily disabled, cost information regarding related paths in the network may not be available until after an attempt to use the failed path. Alternate paths, presently optimal paths, are therefore potentially unknown to other switches in the network until time has been wasted in futile attempts to use the failed path.
It is evident from the above discussion that improved switches and associated protocols are needed to manage redundant communication paths while permitting improved bandwidth utilization of all communication links in a network. In particular, an improved cost information propagation protocol is needed to allow switches in the network to more efficiently discover changes in cost values in the network and to recompute optimal paths through the network resulting from changes in the cost information.
The present invention solves the above and other problems, thereby advancing the state of useful arts, by providing network switch devices and associated switch to switch protocols which permit the operation of multiple links throughout the network involving multiple switches, and which provide for improved utilization of the aggregate bandwidth of all paths in the network. Further, the present invention provides a switch to switch protocol propagating cost information among cooperating network switches operable in accordance with the present invention.
By permitting parallel use of all communication paths and switches in the network, the present invention improves scalability of network communication bandwidth as compared prior techniques. The aggregate bandwidth capability within the entire network may be increased by simply adding additional communication paths and associated switches.
In particular, the present invention includes a protocol operable between switches designed in accordance with the present invention for exchanging cost information regarding the various paths between the switches. Following the initial hello protocol and loop bit negotiation protocol to determine the switches which are in a load balance domain, the cost propagation protocol of he present invention is used to inform all switches of the relative costs of communicating over each of the paths interconnecting the switches.
As used herein, costs include any parameter values that affect the cost of transmitting data through the corresponding switch as measured in financial units and/or performance units. In the preferred embodiment, a single cost parameter is included which identifies the packet switching latency of a switch. The packet switching latency is a measure of the time required for the switch to process a packet received on one port and determine on which (if any) other port the packet should be forwarded. This latency time is a key aspect of the performance of networks having switches in their communication paths. Switches in general are designed to rapidly switch packets from reception port to a transmission port. However, configuration parameters and design factors within each switch may vary the latency time of packet processing within the switch.
The cost propagation protocols of the present invention therefore enable latency, and other cost information, to be efficiently exchanged among the switches of a network. Unlike prior cost propagation techniques, the methods of the present invention periodically generate cost information so as to maintain updated cost information within all switches of the network (all within a load balance domain). By periodically updating cost information, the present invention avoids congestion of network message traffic as compared to techniques which updated cost information each time any cost parameters changed.
Further, the protocol of the present invention is more robust than prior solutions. Should a switch in the load balance domain lose its cost information tables (perhaps by an inadvertent reset), the cost information will be updated at the next scheduled, periodic exchange.
At each periodic update of cost information, each switch generates a switch cost packet and transmits the packet out on each of its ports in the load balance domain. The switch cost packet includes a hop count field and at least one cost information portion. A switch which receives the switch cost packet updates its cost records in a table entry corresponding to the transmitting switch. As noted herein below, a loop bit offset value may be used as a unique ID to rapidly locate the corresponding table entry. The receiving switch then increments the hop count value in the switch cost packet and transmits the updated packet out on each of its ports within the load balance domain (other than the port from which the packet was just received). The process repeats for each switch receiving the updated switch cost packets from other switches until the process converges by updating all cost information in all switches of the load balance domain.
Several techniques are employed in parallel by the methods of the present invention to assure that the process will converge and converge rapidly with all switches receiving current cost information. First, if the hop count exceeds a predetermined maximum value, the packet is discarded rather than transmitted on to another switch. The predetermined value assures that the cost propagation packet will not xe2x80x9cwanderxe2x80x9d through the network of switches for longer than a predetermined maximum time (equivalent to the time required to traverse switches for the maximum hop count). Also, a retransmission counter in the cost packet is also used to assure that the packet is not xe2x80x9cstuckxe2x80x9d in a retransmission from one switch to another. Each cost information packet is acknowledged by the receiving switch with a packet (a cost information response packet) sent back to the originating switch. When the originating switch does not receive an acknowledgment after a timeout period, the cost information packet is retransmitted by the originating switch (through the port attached to the receiving switch which failed to acknowledge the previous transmission). The retransmission count is incremented each time the cost packet is retransmitted from a switch. If the retransmission count exceeds a predetermined count value, the cost packet transmission is terminated. Like the hop count this technique prevents a particular cost packet transmission from absorbing too much time within the transmitting switch.
Secondly, the loop bit offset value is used (as discussed herein below) as a unique identifier for each switch in a load balance domain. The value assigned to each switch is indicative of a bit position in a bit mask field of the cost packet (as well as other packets discussed herein below). Each switch which transmits a cost packet (the originator of the packet as well as each switch which retransmits the cost packet) sets its corresponding bit as described by the loop bit offset value. When a cost packet is received, if the receiving switch""s bit in the bit mask is set, the packet has made a loop back to the receiving switch. In such a case, the received cost packet is discarded (not transmitted further) because it has already been processed by the receiving switch.
A sequence number field in the packets is used to identify a particular occurrence of the periodic exchange of cost information among the switches. Until the cost information exchanges among the switches converges, all cost information packets associated with this occurrence of the exchange use the same sequence number. Each switch increments the sequence number field in cost information packets generated by that switch prior to the next periodic exchange of cost information. The sequence number for cost packets received from other switches to be propagated through the load balance domain is left intact as the cost information is forwarded for propagation in the load balance domain.
A current set of cost information saved within the switches is retained while the next periodic exchange of cost information is attempting to converge. New cost information eventually replaces previous cost information in the switches once the exchange of the new cost information converges to completion among the switches.
Still another aspect of the present invention lies in the architecture wherein cost information is calculated and propagated at the physical layer of the network communication protocols. As is known in the art, computer network communication protocols are often designed in accordance with a standard layered model. For example, the well known ISO (International Standards Organization) defines an OSI (Open Systems Interconnect) standard model for computer network communications. The model has seven layers with the lowest layer, the link layer, being designated as layer 1.
The cost calculation and propagation of the present invention is performed at the physical layer (i.e., layer 2 of the seven layer model). By comparison, prior techniques performed such cost information exchange at layers 3 and higher. By computing and exchanging such information at the physical layer (layer 2), the methods and switches of the present invention more readily utilize real-time, physical link performance information and measurements to estimate actual link costs.
The cost information propagation protocol of the present invention therefore rapidly converges on complete dissemination of cost information among all switches of a load balance domain. Further, the protocols of the present invention provide consistent periodic updates of cost information about all switches in the load balance domain to all switches in the domain. Still further, the protocols of the present invention estimate actual link costs using information available at lower layers of the protocol xe2x80x9cstackxe2x80x9d (i.e., at the physical level (layer 2) of the ISO/OSI model).
The above, and other features, aspects and advantages of the present invention will become apparent from the following descriptions and attached drawings.


A planar type superconductive thin film transistor using oxide superconductive materials and utilizing a long distance proximity effect is obtained with a good reproducibility.. In order to obtain the planar type superconductive transistor utilizing the long distance proximity effect, an interlayer separating film that plays a similar role with resists is used together with conventional resists in high temperature annealing process.

The present invention relates to a structure of a superconductive thin film field effect transistor and to a high yield and productive fabrication method of the same.
Conventionally, Nb-Ge metallic material (for example Nb.sub.3 Ge) is used as a superconductive material. Since these materials have relatively large coherent length, a Josephson device in which an insulator is pinched between superconductive materials can be fabricated relatively easily, and such devices as a transistor using proximity effect can be made. Superconductive materials using conventional metals also have an advantage in that, since they have no anisotropy in their structure, electronic devices can be fabricated without considering orientation and other related issues.
However, superconductive materials using these metallic materials have a low Tc (superconductive critical temperature is referred to simply as Tc hereinafter), such as 23 K. or less. In applying them to industrial uses, they would clearly be more useful if their Tc were above the temperature of liquid nitrogen (77 K.). To that end, it has been being strongly desired to build up electronic devices using oxide superconductive materials.
Nevertheless, electronic devices using oxide superconductive materials have not been constructed so far, mainly due to the following two reasons: First, high Tc superconductive materials have problems in that their coherent length is short and they have anisotropy in their crystal structure; and second, high temperature annealing is necessary in processing them. The former problem requires that the devices be processed precisely, and renders processing of the devices difficult. The latter problem causes diffusion of atoms in annealing and thereby adversely affects characteristics of the devices.
More recently, a phenomenon called a long distance proximity effect has been confirmed. When a non-superconductive material having a perovskite structure which is like a parent material of oxide superconductive materials is enclosed between a plurality of oxide superconductive materials, superconductive current flows even if the distance between the oxide superconductive materials is larger than that in the conventional proximity effect. The cause of this phenomenon remains unclear, though by using the long distant proximity effect, the problem of coherent length of the oxide superconductive materials may possibly be overcome, so that such electronic devices as transistors using the oxide superconductive materials may be fabricated. Presently, however, electronic devices using the long distance proximity effect have not been obtained.
Accordingly, it is an object of the present invention to establish a structure of and a process for fabricating such electronic devices, including superconductive transistors in particular, using the aforementioned long distance proximity effect.
It is obvious that it is desirable to use a mono-crystal thin film of an oxide superconductive material whose coherent length is long in the direction of ab plane; thus, a planar type structure using c-axis oriented film is naturally desirable. However, since a process for fabricating such an ideal structure has not been known, only laminated type electronic devices, whose coherent length is short and junctioned in the ab-axis direction, and incomplete planar-type electronic devices have been obtained.
Furthermore, in terms of the process for fabricating them, resists and others used in prior art semiconductor fabricating processes cannot sustain the film forming temperature of the oxide superconductive materials.

Fabrication method of superconductive thin film transistor

Semiconductor Energy Laboratory Co., Ltd.


An infusion sleeve for an ultrasonic tissue removal surgical tool includes a sleeve designed to surround the ultrasonically driven tip of the surgical tool and create an irrigation fluid channel thereinbetween. The sleeve includes a flexible portion which permits retraction of the distal end thereof to permit contact between the tip of the surgical tool and body tissue to be destroyed or removed. The infusion sleeve also includes a rigid portion which is designed to prevent collapse of the sleeve around the ultrasonically driven surgical tip and prevent blockage of irrigating fluid flow and subsequent overheating of the tip and damage to adjacent body tissue.

In the prior art, a plurality of hand-held devices have been proposed for removal of body tissue during surgical procedures. One particular surgical device includes an ultrasonically driven surgical tool handpiece that destroys or emulsifies body tissue by contact between the tissue and a vibrating tip of the surgical handpiece. These types of surgical tools are used to remove a wide range of body tissue including removal of cataracts, plaque in arteries or concretions in body tissue such as kidney stones. Included with these surgical handpiece tools are means to introduce irrigation fluid to the surgical site as well as a source of aspiration or vacuum to remove destroyed or emulsified body tissue.
In certain prior art devices, the irrigation fluid is supplied to the operative tip of the surgical tool through a channel created by placement of an infusion sleeve around the operative tip assembly of the tool. U.S. Pat. No. 4,643,717 to Cook et al. discloses an ultrasonic surgical instrument utilizing these types of sleeves. The irrigating fluid supplies a medium for facilitating emulsification of body tissue and a cooling medium to prevent overheating of the vibratory tip and subsequent damage to adjacent body tissue not intended for removal.
Various materials have been utilized in prior art infusion sleeves. U.S. Pat. No. 4,787,889 to Steppe et al. discloses a flexible sleeve made of a synthetic resin such as silicon rubber which is able to fold back or telescope when inserted through an incision. Problems with these types of prior art devices include collapsing of the flexible sleeve in the area of the wound or incision site by pressure from surrounding tissue. This collapsing of the sleeve blocks flow of irrigation fluid to the surgical site and around the vibratory surgical tip causing overheating and damage to body tissue during surgery.
Other prior art devices, as described in the above-mentioned U.S. Pat. No. 4,787,889 to Steppe et al. utilize sleeves made out of metallic materials such as stainless steel. These devices do not collapse as do flexible sleeves but also are not capable of retracting away from the operative tip of the ultrasonic tip, and, therefore, are more difficult to manipulate during surgery.
As such, a need has developed to provide an improved infusion sleeve that combines flexibility and rigidity to facilitate manipulation of the surgical tool by a surgeon while protecting tissue around the wound or incision site from damage due to overheating of the surgical tool tip. In U.S. Pat. No. 4,634,420 to Spinosa et al. an infusion sleeve is disclosed which includes ribs provided around the interior circumference of the sleeve to prevent collapse when the apparatus is inserted into an eye. U.S. Pat. No. 4,983,160 to Steppe et al. discloses an infusion sleeve made of a synthetic resin material which provides sufficient rigidity to prevent collapse under the pressure of the sides of an ocular incision.
U.S. Pat. No. 4,515,583 to Sorich discloses an improved ultrasonic surgical aspirator that discloses a first sleeve configuration made of a rigid material. Alternatively, the sleeve may be made of a resilient silicon rubber material and the ultrasonic surgical tool tip is configured to provide a space between the tip and sleeve when the resilient sleeve material is compressed by the ocular incision site. U.S. Pat. No. 4,808,154 to Freeman discloses another type of infusion sleeve that is designed to prevent collapse around an ultrasonic surgical tool tip. Herein, the infusion sleeve includes a plurality of ribs on the inner surface thereof to maintain irrigation fluid flow around the vibrating surgical tool tip.
In view of the above-mentioned prior art, a need has developed to provide an improved infusion sleeve that combines flexibility and rigidity to facilitate manipulation of a surgical tool as well as prevent damage to adjacent body tissue in the area of the surgical site.
In response to this need, an improved infusion sleeve has been developed which includes a flexible portion to permit retraction away from the operative tip of an ultrasonic surgical tool and a rigid portion which prevents blockage of irrigation fluid and subsequent overheating of the ultrasonic tool as well as damage to adjacent body tissue.

Infusion sleeve for surgical ultrasonic apparatus


A repeater for packet data optical communication between terminal devices includes a first section and a second section. The first section includes a first device for receiving a first optical signal transmitted from a terminal device and for converting the first optical signal into a first electric signal, a second device for frequency-converting the first electric signal to a second electric signal, and a third device for converting the second electric signal into a second optical signal and for transmitting the second optical signal. The second section includes a fourth device for receiving a third optical signal and for converting the third optical signal into a third electric signal, a fifth device for frequency-converting the third electric signal to a fourth electric signal, and a sixth device for converting the fourth electric signal into a fourth optical signal and for transmitting the fourth optical signal to a terminal device.

1. Field of the Invention
This invention relates to a repeater in a data communication network using optical signals. This invention also relates to a repeater system providing an optical communication network including a repeater or repeaters.
2. Description of the Prior Art
A known optical radio communication network includes a transmitter, receivers, and repeaters. In the case where a direct optical path between the transmitter and a receiver is blocked, a repeater generally serves to maintain optical radio communication between the transmitter and the receiver. A repeater, which merely amplifies a received optical signal and then outputs a corresponding stronger optical signal, tends to oscillate since a feedback loop is easily formed between receiving and transmitting sections of the repeater. To prevent such an oscillation problem, an optical signal outputted from a transmitter is made into a time-division packet format so that optical signals inputted into and outputted from a repeater can be different from each other in contents. According to time-division packet communication, real-time transmission of information tends to be difficult.


An improved trap fitting assembly (10) which prevents the spread of smoke and fire through a floor (100) and ceiling (104) supported by a joist (102) in a building is described. The fitting is preferably adapted for mounting in a tub box (12) and uses a flammable T-connector (24) for draining a tub (106) through an overflow pipe (22) and a drain pipe (20) connected to a tub drain (42). The T-connector is mounted inside of a non-flammable threaded nipple (16) which is mounted in an opening (14) in the tub box by jam nut (26) and a ring gasket (28). A non-flammable J-pipe (30), filled with water to a level L--L, threads onto a lower extension (16b) of the nipple and prevents smoke and fire from spreading through the fitting assembly.

(1) Field of the Invention
The present invention relates to an improved trap fitting assembly which prevents smoke and fire from spreading through the fitting which is preferably mounted through a tub box mounted in a flammable floor. In particular, the present invention relates to a trap fitting assembly including a flammable T-connector mounted inside of a non-flammable threaded nipple which extends part of the way through an opening in the bottom of a tub box or other non-flammable support means that is mounted in the floor. A non-flammable J-pipe is connected to an extension portion of the threaded nipple below the tub box. Water is trapped in the J-pipe so that any smoke or fire burning in a building will not be able to travel through the J-pipe, the threaded nipple or the tub box.
(2) Prior Art
Trap fitting assemblies are well known and generally include a non-flammable main conduit which penetrates a floor along a vertical longitudinal axis and a non-flammable J-pipe which is connected to a lower most end of the main conduit Generally, the J-pipe is provided through a pre-formed opening in the floor which is larger in diameter than the conduit. The J-pipe is preferably held in place by drain or tub box structure mounted on or in the floor. This construction is expensive.
My U.S. Pat. No. 4,724,858 describes a firestop stack fitting for sealing the opening of pipes which extend between floors of a building. A non-flammable sleeve is mounted inside a flammable coupling. This fitting works well where a trap is not required.
My U.S. Pat. No. 4,953,235 describes a trap fitting assembly, preferably adapted for a floor drain outlet or tub box, which prevents the spread of fire and smoke through a concrete floor of a building. The fitting uses a flammable coupling embedded in a poured concrete floor. A non-flammable sleeve inside the coupling has an extension portion extending below the floor. A non-flammable J-pipe contains water at a level above the trough of the two upturned legs of the J-pipe. The J-pipe is connected to the extension portion and prevents smoke and fire from going through the floor. This trap fitting assembly is not adapted for use with flammable floors.

Trap fitting assembly for mounting in flammable floors


An optical disc substrate having a reduced thickness and sufficient rigidity is provided which can be of a single-plate structure. It can be compatible with a magneto-optic recording and also with a conventional disc driving means. The substrate consists of a disc supporting portion (21) formed around the center of the substrate and of which one side (21a) provides a surface at which the disc is to be mounted on a disc driving means, and a recording portion (22) formed between the disc supporting portion (22) and a circumference of the substrate and of which one side (22a) provides a recording surface. The disc supporting portion (21) is designed thicker than the recording portion (22) so that the disc supporting surface (21a) and the recording surface (22a) will not lie together in a sample plane. A recess 25 may be formed between the recording portion (22) and disc supporting portion (21), and also a projection (27) may be formed along the circumference of the side (22b). Furthermore, one or more functional layer may be formed on the side (22b) opposite to the recording surface.

1. Field of the Invention
The present invention relates to an optical disc substrate consisting of a disc supporting portion formed around the center thereof and of which one side provides a disc supporting surface, and a recording portion formed between the disc supporting portion and a circumference thereof and of which one side provides a recording surface, and an optical disc incorporating this optical disc substrate. More particularly, it concerns with an optical disc substrate in which the thickness of the disc supporting and recording portions can be determined to attain a high density of recording while maintaining a sufficient rigidity without easy warping of the substrate, and an optical disc incorporating the optical disc substrate.
2. Description of Related Art
These days, researches and developments of various optical information recording systems have been made everywhere in the field of information recording. The optical information recording system is advantageous in many respects. For instance, information can be recorded and reproduced with no contact with a read/write head, information can be recorded with a density higher more than one order of magnitude than the conventional magnetic recording system, and there are available various types of media, such as read-only, recordable and rewritable. As a recording system enabling an inexpensive, large-capacity filing, many application are expected of the optical information recording system to meet industrial needs and home or personal demands.
Among others, the compact discs (CD) and optical video discs (DVD), of the read-only type, have been widely used.
More specifically, a CD comprises an optical disc substrate being a transparent one having formed thereon a pattern of convexities and concavities such as pits and grooves indicative of information, a reflective layer made of a metal film such as aluminum film, and a protective layer formed on the reflective layer to protect the latter against moisture and O.sub.2 in the atmosphere. To reproduce or read information from such an optical disc, a reading light such as laser light is irradiated onto the convexity and concavity pattern from the optical disc substrate side, and the information is detected based on a difference in reflectivity between the incident and return lights.
Recently, a higher density of information recording has been required. To meet this demand, it has been proposed, in a tendency that a light of a shorter wavelength is adopted in reading/writing of optical discs, to use a means for increasing the numerical aperture (NA) of an objective lens provided in an optical pick-up and through which a reading light of a certain wavelength is irradiated to an optical disc, to decrease the light spot diameter. For instance, the NA of objective lens used in an optical disc drive for CD is 0.46, but that of an objective lens used in a player for DVD having recently been catching people's attention for its recording capacity 6 to 8 times higher than CD, is about 0.60.
As the NA of the objective lens is larger as mentioned above, an optical disc substrate through which an irradiated reading light is transmitted should have an increased thickness.
That is, with an objective lens having a larger NA, a larger astigmatic aberration will be caused by a tilt of an optical disc surface with respect to an optical axis of an optical pick-up and thus the tilt angle allowance for the disc surface will be smaller. Note that the tilt angle for CD is 0.6.degree. or less while that for DVD is 0.4.degree. or less.
The allowance of the tilt angle can be determined from a relation 1/(optical disc substrate thickness).times.NA.sup.3, and thus it will easily be affected by the thickness of an optical disc substrate and NA of an objective lens. Namely, when an objective lens having a larger NA is used, the thickness of optical disc substrate should be smaller for a maximum possible allowance of tilt angle.
To meet such requirements, the optical disc substrate for CD is on the order of 1.2 mm while that for DVD is about 0.6 mm.
However, an optical disc substrate having a reduced thickness will have a correspondingly decreased rigidity. Generally, a plate has a flexural rigidity proportional to the third power of its thickness. Therefore, when a plate has the thickness reduced to 1/2of its original one, its rigidity will be 1/8of the original one. Thus, for DVD to keep a sufficient rigidity, they are made of two laminated optical disc substrates attached to each other.
However, to assure a sufficient rigidity of the optical disc by such a method, a process of lamination not required for manufacturing an optical disc substrate usable as a single-plate structure will add to the processes of optical disc substrate production, whereby the productivity will be lower. When producing an optical disc having a double-plate structure in which one of the substrates has a recording layer while the other substrate is a dummy one to reinforce the rigidity of the optical disc, the manufacturing costs will be increased while the productivity be lowered.
As discussed in the above, an optical disc substrate for use in magneto-optic recording using a magnetic field modulation should be of a single-plate structure. The above-mentioned laminated optical disc substrate cannot be used for magneto-optic recording based on the magnetic field modulation.
In these circumstances, an optical disc using a single thin substrate has been demanded increasingly more.
However, when an optical disc using a single thin substrate is played with a DVD-oriented disk driving means to spin the optical disc, the disk driving means cannot catch the optical disc by in the direction of the disc thickness a chucking mechanism thereof. Thus, such an optical disc is not compatible with any other disk driving means than dedicated for the optical disc itself. It will be necessary to provide a new disk driving means for such an optical disc, which however will disadvantageously lead to an increased running cost.

Optical disc substrate having relatively thicker central supporting portion and relatively thinner recording portion