An apparatus for smoothing a surface of a substrate includes an ionizer to form gas cluster particles; a power supply to accelerate the gas cluster particles; a triode/Einzel lens combination assembly to focus the accelerated gas cluster particles; a permanent magnet beam filter; scan plates to irradiate the filtered accelerated gas cluster particles onto a surface of a workpiece situated in a reduced pressure atmosphere chamber; and a substrate loading/unloading mechanism to load and unload the workpiece. The ionizer includes an alignment device wherein the alignment device includes a X/Y translation element and an angular translation element. The substrate loading/unloading mechanism provides a workpiece from a plurality of workpieces onto a holder positioned at a first position within the reduced pressure atmosphere chamber, the first position being substantially parallel to a central axis of a flow of the filtered accelerated gas cluster particles. The substrate loading/unloading mechanism also moves the holder with a workpiece thereon to a second position, the second position being substantially perpendicular to the first position and the central axis of a flow of the filtered accelerated gas cluster particles.

The present invention is directed to a gas cluster ion beam apparatus. More particularly, the present invention is directed to a gas cluster ion beam apparatus that enables effective separation of monomer or molecular ions from the gas cluster ion beam.
Moreover, the present invention is directed to a gas cluster ion beam apparatus capable of controlling multiple independent adjustments through an automated electronic control system.
Energetic-ion sputtering has been conventionally used for etching and thinning in manufacturing and depth-profiling in analytic instruments. However, energetic-ion sputtering causes subsurface damage and accumulated roughness because energetic-ion sputtering uses monomer ions. Individual monomer atoms or molecules have energies on the order of thousands of electron volts that cause the residual surface damage.
To avoid the residual surface damage, gas cluster ion beam process devices have been developed. One example of such an apparatus, as well as the creation and acceleration of such a conventional gas cluster ion beam, is described in U.S. Pat. No. 5,814,194to Deguchi et al. The entire contents of U.S. Pat. No. 5,814,194 are hereby incorporated by reference. Another example of a gas cluster ion beam apparatus is described in U.S. Pat. No. 5,459,326 to Yamada. The entire contents of U.S. Pat. No. 5,459,326 are hereby incorporated by reference.
Gas cluster ion beams can be used for etching, cleaning, and smoothing of material surfaces in certain applications. These conventional gas cluster ion beams comprise gas clusters having nano-sized aggregates of materials that are gaseous under conditions of standard temperature and pressure. Such clusters are typically formed of aggregates of approximately 20 to approximately several thousand atoms or molecules loosely bound together. The gas clusters can be ionized by electron bombardment or other means, permitting the gas clusters to be formed into directed beams of known and controllable energy. The larger sized gas clusters are the most useful because the larger sized gas clusters are able to carry substantial energy per cluster ion, while yet having only modest energy per atom or molecule.
The gas clusters disintegrate on impact with each individual atom or molecule carrying only a small fraction of the total cluster energy. Consequently, the impact effects of large clusters, while substantial, are limited to only a very shallow surface region, thereby enabling ion clusters to be effective for a variety of surface modification processes, without the tendency to produce deeper subsurface damage. As noted above, deeper subsurface damage is a characteristic of monomer or molecular ion beam processing.
One characteristic of gas cluster ion interactions with surfaces is ultra-shallow interaction depth. The gas cluster ion interactions also exhibit inherent smoothing and planarization behaviors. These behaviors can be extraordinary when the gas cluster ion impacts upon rough or non-planar surfaces. Since the atoms within a cluster are able to interact with each other as the cluster disintegrates upon impact, some of the energy carried by the cluster is converted into energy of individual atoms within the cluster. This converted energy is dissipated in all directions within the plane of the target surface, thereby producing excellent smoothing behavior on most materials, including diamond. Lastly, the gas cluster ion interactions demonstrate an ability to produce enhanced surface chemical reactions with reactive cluster species.
Gas cluster ions deposit their total energy into the impact site upon the target surface. The atoms within a gas cluster ion have small individual energies that prevent the atoms from penetrating beyond very shallow depths of a few atomic layers. Consequently, a gas cluster ion deposits considerable energy into a much shallower region on the target surface than would a monomer or molecular ion of equal energy. Similarly, since the gas cluster ion has much greater mass and momentum, a gas cluster ion impact can generate much more intense pressure pulse effects than those associated with monomer ion bombardment.
Computer simulations of gas cluster ion impacts predict peak momentary temperatures of the order of 100,000xc2x0K in combination with pressure pulses in the range of millions of pounds per square inch. These transient high temperature and pressure conditions within the impact volume occur while the gas atoms from the cluster are being dynamically mixed with the target material atoms, thereby enabling highly enhanced chemical reaction properties to be observed or realized.
Conventionally, gas cluster ion sources produce gas clusters ions having a wide distribution of sizes, N (where N=the number atoms or molecules in each cluster). Such atoms in a cluster are not individually energetic enough (on the order of a few electron volts) to significantly penetrate a surface to cause the residual surface damage typically associated with the other types of ion beam processing, such as energetic-ion sputtering.
However, the gas cluster ion can be made sufficiently energetic (some thousands of electron volts), to effectively etch, smooth or clean surfaces. This allows the gas cluster ion to be used to smooth surfaces of various materials to nearly an atomic scale by utilizing all-dry vacuum methods. Such materials include, but are not limited to, silicon, compound semiconductors, dielectric wafers, films and high-dielectrics, thin metal and ferromagnetic films, and electro-optics.
An example of a prior art gas cluster ion beam apparatus 100 is illustrated in FIG. 1. As illustrated in FIG. 1, the gas cluster ion beam apparatus 100 includes a vacuum vessel 102 that is divided into three communicating chambers, a source chamber 104, a ionization/acceleration chamber 106, and a processing chamber 108. The three chambers are evacuated to suitable operating pressures by vacuum pumping systems 146a, 146b, and 146c, respectively. A condensable source gas 112 (for example argon, Ar) is admitted under pressure through gas feed tube 114 to stagnation chamber 116 and is ejected into the substantially lower pressure vacuum through a properly shaped nozzle 110.
The gas feed tube 114, the stagnation chamber 116, and the nozzle 110 together constitute the gas feed assembly, thereby producing a supersonic gas jet 118. Cooling, resulting from the expansion in the jet, causes a portion of the gas jet 118 to condense into clusters, each cluster consisting of from several to several thousand weakly bound atoms or molecules.
In FIG. 1, a gas skimmer 120, having an aperture, separates the gas products that have not been formed into a cluster jet from the cluster jet. This separation minimizes the pressure in the downstream regions where higher pressures would be detrimental (e.g., ionizer 122, high voltage electrodes 126, and process chamber 108). Suitable condensable source gases 112 include, but are not necessarily limited to, argon; nitrogen and other inert gases; oxygen; carbon dioxide; oxides of nitrogen; and sulfur hexafluoride.
After the supersonic gas jet 118 containing gas clusters has been formed, the clusters are ionized in ionizer 122. The ionizer 122 is typically an electron impact ionizer that produces thermoelectrons from one or more incandescent filaments 124. The ionizer 122 accelerates and directs the electrons causing the electrons to collide with the gas clusters in the gas jet 118, at the point where the jet passes through the ionizer 122. The impact of the electrons causes electrons from the clusters to be ejected, thereby causing a portion of the clusters to become positively ionized. The positive ionization is usually, but not necessarily, with a single charge.
A set of suitably biased high voltage electrodes 126 extracts the cluster ions from the ionizer, forming a beam. The biased high voltage electrodes 126 then accelerates the cluster ions to a desired energy (typically adjustable from 1 keV to several tens of keV) and focuses the cluster ions to form a gas cluster ion beam 128.
Filament power supply 136 provides voltage VF to heat the ionizer filament 124. Anode power supply 134 provides voltage VA to accelerate thermoelectrons emitted from filament 124 to cause the thermoelectrons to bombard the cluster containing gas jet 118 to produce ions. Extraction power supply 138 provides voltage VE to bias a high voltage electrode to extract ions from the ionizing region of the ionizer 122 and to form the gas cluster ion beam 128. Accelerator power supply 140 provides voltage VAcc to bias a high voltage electrode with respect to the ionizer 122 so as to result in a total gas cluster ion beam acceleration energy equal to VAcc. One or more lens power supplies, 142 and 144, bias high voltage electrodes with potentials, VL1 and L2, to focus the gas cluster ion beam 128.
A workpiece 152, which may be a semiconductor wafer or other workpiece to be processed by gas cluster ion beam 128, is held on a workpiece holder 150, disposed in the path of the gas cluster ion beam 128. Since most applications contemplate the processing of large workpieces with spatially uniform results, a scanning system is desirable to uniformly scan the gas cluster ion beam 128 across large areas to produce spatially homogeneous results.
Two pairs of orthogonally oriented electrostatic scan plates 130 and 132 are utilized to produce a raster or other scanning pattern across the desired processing area. When beam scanning is performed, the gas cluster ion beam 128 is converted into a conical scanned gas cluster ion beam 148, which scans the entire surface of workpiece 152.
The core of this technology is predicated on the efficient generation, ionization, and controlled transport of a gas cluster ion beam 128 made up of clusters of gaseous ions to the surface of a workpiece 152 to be modified. A stream of pure gas, for example argon, is introduced into a vacuum environment through a modified Laval nozzle 118. The modified Laval nozzle 118 has a very small throat aperture and expands causing the gas to form large molecular clusters which exit the horn of the nozzle 118 in a concentrated core stream surrounded by a more diffuse cloud of monomer atoms or molecules.
The gas jet 118 has a central core of gas clusters, which is the useful portion of the gas stream and must be separated from the balance of the non-clustered gas atoms or molecules. This is done by directing the gas jet 118 through the small aperture of a gas skimmer 120 that passes the core cluster beam into a high vacuum ionization/acceleration chamber 106. The small aperture of a gas skimmer 120 skims the non-clustered gas molecules to be pumped away. This beam of gas clusters is then passed through an array of high voltage electrodes 126, exiting as a fully formed gas cluster ion beam 128, to be used in the aforementioned processing applications.
Considering the variety of potential production applications in the semiconductor and in other industries, there is great need for a gas cluster ion beam processing equipment that is compatible with the low maintenance, high production requirements of such industries. There have been several problems with conventional gas cluster ion beam equipment, which has primarily been designed for and used in laboratory or research environments. These problems have heretofore hindered the successful application of gas cluster ion beam processing in high volume industries.
One example of a problem with the conventional gas cluster ion beam equipment is that the conventional gas cluster ion beam equipment lacks a simple, inexpensive, and reliable means for separating monomer (or in the case of molecular gases, molecular) ions from the gas cluster ion beam. As noted above the inclusion of the monomer ions in the gas cluster ion beam can cause unwanted surface damage to the substrate being processed.
Moreover, the conventional gas cluster ion beam apparatus lacks efficient and automatic means for sequentially handling workpieces to move the workpieces into and out of the vacuum processing environment. This is important in a production environment as opposed to a research or laboratory environment. If the workpiece cannot be handled efficiently, the productivity of the gas cluster ion beam apparatus is negatively impacted.
Lastly, conventional gas cluster ion beam apparatus have no effective and fast means for aligning the neutral cluster jet produced by the nozzle with the aperture of the gas skimmer. Aligning the nozzle/gas skimmer assembly so that the beam exiting the nozzle is centered on the skimmer aperture and normal to and centered in the discs of the high voltage electrodes assembly is critical. Also since the ion beam is somewhat divergent as it leaves the nozzle, it is essential to have the correct spacing between the nozzle exit and the gas skimmer entrance. If this spacing is too large many of the clusters at the outer perimeter of the beam will be clipped away by the skimmer causing a loss of cluster beam throughput and an overall loss of performance.
Thus, it is an object of the present invention to provide an automated electronic control system capable of controlling the multiple independent adjustments of the gas cluster ion beam apparatus under programmable control to permit quick and efficient setup of a pre-selected beam condition and to maintain that condition during processing and to manage the sequential processing of multiple workpieces.
Another object of the present invention is to provide a simple, effective, reliable and inexpensive means for removing monomer or molecular ions from the gas cluster ion beam.
It is a further object of the present invention to provide automatically controllable endstation means for transferring workpieces to be processed into and out of the processing chamber for rapid, efficient production flow of workpieces through the gas cluster ion beam processor.
It is a still further object of the present invention to provide improved means for adjustable alignment of nozzle and gas skimmer to optimize gas cluster ion beam production. It is an objective that the alignment is accurate and repeatable and that the adjustments are fast and simple.
The present invention provides a solution to the problems set forth above with respect to the conventional gas cluster ion beam apparatus.
One aspect of the present invention is a substrate surface treatment method. The method forms gas cluster particles comprising a plurality of atoms or molecules; accelerates the gas cluster particles; filters accelerated gas cluster particles using a permanent magnet beam filter; and irradiates the accelerated magnetically selected gas cluster particles onto a surface of a substrate in a reduced pressure atmosphere.
A second aspect of the present invention is a substrate surface treatment apparatus. The apparatus includes an ionizer to form gas cluster particles comprising a plurality of atoms or molecules; a power supply to accelerate the gas cluster particles; a permanent magnet beam filter to select certain accelerated gas cluster particles; and scan plates to irradiate the magnetically filtered accelerated gas cluster particles onto a surface of a substrate in a reduced pressure atmosphere.
A third aspect of the present invention is a substrate surface treatment method. The method forms gas cluster particles comprising a plurality of atoms or molecules; accelerates the gas cluster particles; focuses the accelerated gas cluster particles using a lens combination to realize a long focal length; and irradiates the accelerated magnetically selected gas cluster particles onto a surface of a substrate in a reduced pressure atmosphere.
A fourth aspect of the present invention is a substrate surface treatment apparatus. The apparatus includes an ionizer to form gas cluster particles comprising a plurality of atoms or molecules; a power supply to accelerate the gas cluster particles; a lens combination to focus the accelerated gas cluster particles to realize a long focal length; and scan plates to irradiate the magnetically filtered accelerated gas cluster particles onto a surface of a substrate in a reduced pressure atmosphere.
A fifth aspect of the present invention is an apparatus for smoothing a surface of a substrate. The apparatus includes an ionizer to form gas cluster particles comprising a plurality of atoms or molecules; a power supply to accelerate the gas cluster particles; a lens assembly to focus the accelerated gas cluster particles; a filter to filter the focussed gas cluster particles; scan plates to irradiate the filtered accelerated gas cluster particles onto a surface of a workpiece situated in a reduced pressure atmosphere chamber; and a substrate loading/unloading mechanism to load and unload the workpiece. The substrate loading/unloading mechanism provides a workpiece from a plurality of workpieces onto a holder positioned at a first position within the reduced pressure atmosphere chamber, the first position being substantially parallel to a central axis of a flow of the filtered accelerated gas cluster particles. The substrate loading/unloading mechanism also moves the holder with a workpiece thereon to a second position, the second position being substantially perpendicular to the first position and the central axis of a flow of the filtered accelerated gas cluster particles.
A sixth aspect of the present invention is an apparatus for smoothing a surface of a substrate. The apparatus includes an ionizer to form gas cluster particles comprising a plurality of atoms or molecules; a power supply to accelerate the gas cluster particles; a lens assembly to focus the accelerated gas cluster particles; a filter to filter the focussed gas cluster particles; scan plates to irradiate the filtered accelerated gas cluster particles onto a surface of a workpiece situated in a reduced pressure atmosphere chamber; and a substrate loading/unloading mechanism to load and unload the workpiece. The ionizer includes an alignment device wherein the alignment device includes a X/Y translation element having micrometer driving heads with opposing return spring assemblies and an angular translation element having micrometer driving heads with opposing return spring assemblies.
A seventh aspect of the present invention is an apparatus for smoothing a surface of a substrate. The apparatus includes an ionizer to form gas cluster particles comprising a plurality of atoms or molecules; a power supply to accelerate the gas cluster particles; a triode/Einzel lens combination assembly to focus the accelerated gas cluster particles; a permanent magnet beam filter to filter the focussed gas cluster particles; scan plates to irradiate the filtered accelerated gas cluster particles onto a surface of a workpiece situated in a reduced pressure atmosphere chamber; and a substrate loading/unloading mechanism to load and unload the workpiece. The ionizer includes an alignment device wherein the alignment device includes a X/Y translation element having micrometer driving heads with opposing return spring assemblies and an angular translation element having micrometer driving heads with opposing return spring assemblies. The substrate loading/unloading mechanism provides a workpiece from a plurality of workpieces onto a holder positioned at a first position within the reduced pressure atmosphere chamber, the first position being substantially parallel to a central axis of a flow of the filtered accelerated gas cluster particles. The substrate loading/unloading mechanism also moves the holder with a workpiece thereon to a second position, the second position being substantially perpendicular to the first position and the central axis of a flow of the filtered accelerated gas cluster particles.


A method and system are provided including a data protection module; a display; and a data protection processor in communication with the data protection module and operative to execute processor-executable process steps to cause the system to: present a user interface on a display, the user interface including one or more application packages; receive selection of one of the one or more application packages; present on the display a user-entry field to receive an end-user-role associated with an administrative function, wherein the end-user-role is authorized to access at least one CDS view; receive an input in the user-entry field, wherein the input is one of the end-user-role and a request for assistance; determine whether the selected application package includes at least one core data service (CDS) view; determine whether a data control language (DCL) layer is provided for each included CDS view; and automatically generate the DCL layer for each included CDS view if the DCL layer is not provided for the included CDS view. Numerous other aspects are provided.

Enterprises typically use software applications and application-related services in the execution of their businesses. The application may retrieve data from a database to display to an end user in an application view based on an end user query. For each application area, hundreds (e.g., 300 to 400) of views may be possible, depending on the executed end user query, which means there may be hundreds of different ways to access the data. Different end users may be authorized to access different aspects of the data based on their role in the enterprise. During application development, a developer may include information in the application which specifies data access restrictions. However, including restriction information for each possible view may be time-consuming, cumbersome, and may result in over- or under-authorization of data access.
Systems and methods are desired which support efficient and effective data protection.

Simplifying data protection in CDS based access


The present invention describes materials and methods for forming radiation curable polymer network materials, including coatings, pre-pregs and fiber-reinforced composites. The polymer network materials of the present invention exhibit much lower shrinkage after radiation curing than previous materials and methods, improving the adhesion associated with coatings and pre-pregs, and part fit-up when used to make composite articles.. The present invention also describes an improved method for bonding together articles made by the materials and method of the invention, which results in high-strength bonds between articles.

1. Field of the Invention
This invention is related generally to materials and methods for the fabrication of radiation curable composites and coatings, and more particularly to materials and methods for forming radiation curable polymer network coatings and fiber reinforced pre-pregs and structural composites.
2. Background of the Invention
The use of radiation to cure coatings or composites is advantageous because environmentally hazardous solvents are not released during the curing process. In addition, the curing takes place very quickly, and at low temperatures compared to conventional thermal curing. The lower temperatures made possible with radiation curing reduce residual mechanical stresses that accompany conventional thermal curing.
Several processing methods are known for curing composites with radiation, and they are typically divided into two general categories: liquid state radiation curing, which requires the use of a mold, and solid-state radiation curing, which allows the curing of free-standing objects.
Liquid state radiation curing usually involves the injection of a resin into a mold containing reinforcement fibers. Electron beams penetrate into the mold to crosslink the liquid resin matrix. The mold determines the composite's final shape after it is crosslinked to a solid.
Solid state radiation curing involves first producing a self-supporting and easily handled solid object known in the art as a "green-body", followed by radiation curing. The intermediate stage of producing green bodies is known in the art as the "B-stage". Curing while the resin matrix is in a solid state is also known as "free-standing" curing, since a mold is not required during the radiation curing process. The mechanical and thermal properties of a green-body object are improved by subsequent radiation crosslinking.
There are a number of processing and cost advantages to free-standing curing. U.S. Pat. No. 5,173,142, issued on Dec. 22, 1992 describes how free-standing curing can be used to assemble a hollow section assembly. The cost advantages of using free-standing curing instead of conventional steel stamping at moderate production quantities are described in the technical article by D. L. Goodman, D. L. Birx, G. R. Palmese and A. Chen, entitled "Composite Curing with High Energy Electron Beams," in the Journal of the Society for the Advancement of Material and Process Engineering Vol. 41, 207 (1996).
A generic problem in fabricating large structural composite parts is the difficulty of part fit-up. In applications involving the assembly of multiple parts, such as in automotive or aircraft applications, good part fit-up (which refers to how well parts fit together) is necessary to allow final assembly, as well as for aerodynamic and aesthetic reasons. Unlike ductile metals, where the final shape can be modified by mechanical means at the final stages of assembly, rigid polymer matrix composites must achieve part fit-up by maintaining accurate fabrication tolerances.
In conventional composite processing (such as autoclave curing of aircraft composites), part fit-up problems are primarily caused by residual thermal stresses due to thermal expansion mismatch between fiber reinforcement and resin matrix upon cooling.
A major advantage of low-temperature curing processes such as radiation curing is a reduction in residual thermal stresses associated with conventional thermal curing methods. However, radiation curing has an analogous problem: resin shrinkage during curing. In composites, resin shrinkage leads to internal stresses which can cause composite warpage and poor part fit-up. Shrinkage also leads to higher process engineering costs, since molds must be oversized or oddly-shaped to compensate for shrinkage and warpage. In coating and pre-peg applications, shrinkage can contribute to poor adhesion, especially to metal substrates.
Many conventional resin systems used in radiation curing shrink significantly when cured. Volumetric shrinkage values for common acrylic monomers arc given in a 1964 Rohm and Haas Company (Washington Square, Pa.) technical report entitled "Volume Shrinkage During Polymerization of Acrylic Monomers," and range from 11-30%. Linear shrinkage of acrylated oligomers are listed in a 1996 UCB Radcure Product Specification entitled "UV/EB Curable Oligomers and Shrinkage Behavior," available from UCB Chemicals Corp., Radcure Business Unit, 2000 Lake Park Dr., Smyrna, Ga., and correspond to volumetric shrinkages of 7-25%. A typical resin formulation, incorporating such oligomers and monomers, will have a volumetric shrinkage of 9-15%.
As described in Chapters 1 and 9 of the book "Radiation Curing, Science and Technology," edited by S. P. Pappas (Plenum Press, NY, 1992), one possible approach to reducing shrinkage of radiation-curable resins is the use of cationic polymerization via cationic initiators possessing highly non-nucleoplilic anions (PF--, AsF-- or SbF--). This is an alternative to the more common radiation-curable resin systems of the free-radical type, which possess carbon-to-carbon double bonds that cross-link upon exposure to radiation.
Radiation-induced cationic polymerization has shown lower shrinkage (typically about 6%) than free-radical systems. Cationic catalysts are, however, easily poisoned by nucleophilic resin components, contaminants or fiber sizings, making radiation curin via cationic mechanism difficult. This is especially true for free-standing curing, where the presence of weakly nucleophilic urethane groups or of highly nucleophilic resin "B" components such as amines are incompatible with the use of cationic catalysts.
There is thus needed a method for formulating radiation-curable resins with low shrinkage for use in composite and coating applications, especially where free-standing curing is desired. There is also need a method which eliminates or overcomes the poisoning problem associated with cationic polymerization.
Accordingly, it is an object of the invention to provide a radiation curable polymer network.
Another object of the invention is to provide a radiation cured polymer network that has a reduced shrinkage and warpage.
Another object of the invention is to provide a method for forming radiation curable coatings, composites and pre-pregs made with the radiation curable polymer network of the present invention.

Method of making fiber reinforced composites and coatings


Embodiments described herein may operate to compare an illuminance corresponding to a signal from an image sensor array (ISA) element in a production imaging system with an illuminance associated with optical flare incident to an ISA from which the ISA element is selected. The ISA element may be identified as unusable if the illuminance corresponding to the signal from the ISA element is less than the illuminance associated with the optical flare incident to the ISA.

Image sensors are widely used in a variety of consumer electronic devices, including digital cameras and cellular telephones with built-in digital cameras. An image sensor may comprise a matrix of sensor elements. Because unusable image sensor elements may sometime be compensated for, identification of unusable image sensor elements may increase manufacturing yield and lower production costs.
Unusable sensor elements may include "bright defects" and "dark defects." Some bright and dark defects may be of a "stuck pixel" variety. That is, an output signal from a stuck sensor element may register a fixed signal level regardless of the brightness of light incident to the element. "Brightness of light" may hereinafter be referred to using the more precise term, "illuminance." Units of lux, or lumens per square meter, may be used as a measure of illuminance.
An image sensor may convert light to analog sensor element output signals. An analog to digital converter (ADC) may convert the sensor element output signals to a digital format. A least significant bit (LSB) associated with the ADC may establish a granularity with which illuminance sensed by the sensor element may be measured. Thus, in the field of digital imaging, illuminance may be expressed in LSB units.
A dark defect may also result from a dust particle lodged adjacent to the sensor element. The dust particle may block some or all of the light that might otherwise impinge on the sensor element. If all light is blocked, the sensor element output signal may remain fixed as the illuminance incident to the sensor element changes. If the incident light is only partially blocked, and the partially-blocked sensor element is not stuck, the element output signal may vary as the incident illuminance varies. In the latter case, however, the output signal may not be as large as if the sensor element were not partially blocked.
Current methods may identify unusable sensor elements at a production facility following fabrication. Each production sensor may be tested and calibrated under controlled conditions. Such methods may incur substantial cost, and may fail to identify dark defects resulting from dust particles.
Consider, for example, a cellular telephone with a built-in camera. The camera sensor may have been tested and calibrated at the semiconductor manufacturing facility, following fabrication and before shipment to a cellular telephone manufacturer. During camera module assembly, a dust particle inside the camera module may break free and land on the surface of one or more sensor elements. The resulting dark defect may subsequently manifest itself as a cluster of dark pixels on captured images. Thus, there is a need to identify and rectify such defects.

This patent is subject to a terminal disclaimer.

Image sensor defect identification using optical flare


A vehicle control system defines a set of predetermined criteria relating to the motion of the vehicle and a set of vehicle actions associated with the set of predetermined criteria. The vehicle actions each specify a steering action and/or a braking action. Friction data indicative of a frictional attribute (for example, coefficient of friction) of the contact region between the vehicle and the surface is received. The predetermined criteria are modified based on the friction data. When one or more of the predetermined criteria are met, the system applies the corresponding steering and/or braking actions.

Modern vehicles often incorporate some form of stability control system to ensure that the actual path of the vehicle corresponds to the path intended by the driver, particularly during hard braking operations. Such vehicles might also include collision avoidance systems that sense whether an object is within the vehicle's path, and then take corrective action accordingly. This corrective action might take the form alerting the driver or autonomously applying braking and/or steering to reduce the relative velocity between the vehicle and the obstacle.
Prior art systems typically assume that the vehicle can maintain a specified lateral (sideways) and longitudinal (front/back) acceleration, usually about 0.8 g's lateral and 0.9 g's longitudinal. These acceleration values are then used by the system to determine how much braking and steering can be applied while still maintaining suitable traction between the vehicle and the road.
Under certain conditions, such as rain, snow, etc., the actual maximum lateral and longitudinal acceleration capabilities of the vehicle may be reduced. Accordingly, it is desirable to provide improved emergency braking and steering systems in which tire and road friction characteristics are taken into account. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

Methods and apparatus for a vehicle emergency control system


A controller (6) controls an air-fuel ratio of an engine (1) so that an oxygen storage amount of a catalyst (3) provided in an exhaust passage (2) is maintained constant. At this time, the controller (6) computes or estimates the oxygen storage amount separately for a first amount and a second amount, where the first amount is estimated based on a relationship between the first and second amount. The controller (6) controls the air/fuel ratio based on the estimated first amount.

The present invention relates to an engine exhaust purification device provided with a catalyst.
JP-A-H9-228873 published by the Japanese Patent Office in 1997 discloses a technique wherein an oxygen amount stored in a three-way catalyst (hereafter, xe2x80x9coxygen storage amountxe2x80x9d) is estimated based on an engine intake air amount and an air fuel ratio of an exhaust flowing into the catalyst, and engine air-fuel ratio control is performed so that the oxygen storage amount of the catalyst remains constant.
To maintain the NOx (nitrogen oxides), CO and HC (hydrocarbon) conversion efficiency of the three-way catalyst at a maximum, the catalyst atmosphere must be maintained at the stoichiometric air-fuel ratio. If the oxygen storage amount of the catalyst is maintained constant, oxygen in the exhaust is stored in the catalyst even if the air-fuel ratio of the exhaust flowing into the catalyst temporarily becomes lean. Conversely, oxygen stored in the catalyst is released even if the air-fuel ratio of the exhaust flowing into the catalyst temporarily becomes rich, so the catalyst atmosphere can be maintained at the stoichiometric air-fuel ratio.
In an exhaust purification device which performs this control, the conversion efficiency of the catalyst depends on the oxygen storage amount of the catalyst. Therefore, the oxygen storage amount must be precisely computed to control the oxygen storage amount to be constant and maintain the conversion efficiency of the catalyst at a high level.
It would be an advantage to precisely compute an oxygen storage amount in an exhaust purification device for controlling the air fuel ratio of an engine provided with a three-way catalyst so as to maintain the oxygen amount constant, and to maintain the conversion efficiency of the catalyst at a high level.
According to one embodiment there is provided an exhaust purification device for an engine, the device comprising a catalyst provided in an exhaust passage of the engine, a front sensor which detects an oxygen concentration in the exhaust gas flowing into the catalyst, and a microprocessor programmed to compute an oxygen storage amount of the catalyst separately for a high speed component which has a rapid oxygen storage rate and a low speed component which has a slower storage rate than that of the high speed component based on the oxygen concentration of the exhaust gas, assuming that when oxygen is released, the oxygen is released preferentially from the high speed component rather than from the low speed component when the ratio of the low speed component to the high speed component is less than a predetermined value, and control the air-fuel ratio of the engine based on the computed oxygen storage amount so that the oxygen storage amount of the catalyst is a predetermined amount.
According to another embodiment, there is provided a method of estimating an oxygen storage amount of a catalyst within a catalytic converter coupled to an engine. The method comprises estimating a first amount of oxygen stored in the catalyst, the first amount representing a part of the oxygen storage amount, the first amount estimated to change at a first rate; estimating a second amount of oxygen stored in the catalyst, the second amount representing another part of the oxygen storage amount; and wherein the first rate is estimated based on a relationship between the first amount and the second amount.
According to yet another embodiment, there is provided a method of estimating an oxygen storage amount of a catalyst within a catalytic converter coupled to an engine. The method comprises estimating a first amount of oxygen stored in the catalyst, the first amount representing a part of the oxygen storage amount, the first amount estimated to be stored at a first rate; estimating a second amount of oxygen stored in the catalyst, the second amount representing another part of the oxygen storage amount; and wherein the first rate is estimated based on a relationship between the first amount and the second amount.
According to yet another embodiment, there is provided a method of estimating an oxygen storage amount of a catalyst within a catalytic converter coupled to an engine. The method comprises estimating a first amount of oxygen stored in the catalyst, the first amount representing a part of the oxygen storage amount, the first amount estimated to be released at a first rate; estimating a second amount of oxygen stored in the catalyst, the second amount representing another part of the oxygen storage amount; and wherein the first rate is estimated based on a relationship between the first amount and the second amount.
According to yet another embodiment, there is provided a method of controlling the oxygen storage amount of a catalyst within a catalytic converter coupled to an engine. The method comprises estimating a first amount of oxygen stored in the catalyst, the first amount representing a part of the oxygen storage amount, the first amount estimated to change at a first rate; estimating a second amount of oxygen stored in the catalyst, the second amount representing another part of the oxygen storage amount; wherein the first rate is estimated based on a relationship between the first amount and the second amount; and controlling an air/fuel ratio of the engine based on the estimated first amount.
According to yet another embodiment, there is provided a method of controlling the oxygen storage amount of a catalyst within a catalytic converter coupled to an engine. The method comprises estimating a first amount of oxygen stored in the catalyst, the first amount representing a part of the oxygen storage amount, the first amount estimated to be stored at a first rate; estimating a second amount of oxygen stored in the catalyst, the second amount representing another part of the oxygen storage amount; and wherein the first rate is estimated based on a relationship between the first amount and the second amount; and controlling an air/fuel ratio of the engine based on the estimated first amount.
According to yet another embodiment, there is provided a method of controlling the oxygen storage amount of a catalyst within a catalytic converter coupled to an engine. The method comprises estimating a first amount of oxygen stored in the catalyst, the first amount representing a part of the oxygen storage amount, the first amount estimated to be released at a first rate; estimating a second amount of oxygen stored in the catalyst, the second amount representing another part of the oxygen storage amount; wherein the first rate is estimated based on a relationship between the first amount and the second amount; and controlling an air/fuel ratio of the engine based on the estimated first amount.
According to yet another embodiment, there is provided an exhaust purification device for an engine. The device comprises a catalyst provided in an exhaust passage of the engine; a front sensor which detects an oxygen concentration of oxygen flowing into the catalyst; and a microprocessor programmed to: estimate a first amount of oxygen stored in the catalyst, the first amount estimated to change at a first rate; estimate a second amount of oxygen stored in the catalyst; wherein the first rate is estimated based on the oxygen concentration and a relationship between the first amount and the second amount; and control an air/fuel ratio of the engine based on the estimated first amount.
According to yet another embodiment, there is provided an exhaust purification device for an engine. The device comprises a catalyst provided in an exhaust passage of the engine; a front sensor which detects an excess oxygen concentration of oxygen flowing into the catalyst; and a microprocessor programmed to: estimate a first amount of oxygen stored in the catalyst, the first amount estimated to be stored at a first rate; estimate a second amount of oxygen stored in the catalyst; wherein the first rate is estimated based on the excess oxygen concentration and a relationship between the first amount and the second amount; and control an air/fuel ratio of the engine based on the estimated first amount.
According to yet another embodiment, there is provided an exhaust purification device for an engine. The device comprises a catalyst provided in an exhaust passage of the engine; a front sensor which detects a deficient oxygen concentration of oxygen flowing into the catalyst; and a microprocessor programmed to: estimate a first amount of oxygen stored in the catalyst, the first amount estimated to be released at a first rate; estimate a second amount of oxygen stored in the catalyst; wherein the first amount is estimated based on the deficient oxygen concentration and a relationship between the first amount and the second amount; and control an air/fuel ratio of the engine based on the estimated first amount.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.


A magnetic switch apparatus (10) detects relative movement between first (12) and second (14) members and defeats attempted external magnetic manipulation of the apparatus. A rod-shaped, first switch element (20) is positioned transverse to and centrally aligned with a convex, second switch element (22) and spaced therefrom. A ring-shaped first magnet (26) is positioned about the first switch element (20) and spaced from the second element (22) in order to pull a ferromagnetic body (24) into a switch-open position out of contact with the second switch element (22) with these components mounted to the first member (12). A second magnet (18) mounted to the second member (14) is positioned and magnetically sufficient to pull the body (24) into a switch-closed position in contact with both of the switch elements (20, 22) when the members (12, 14) are in an adjacent position.

1. Field of the Invention
The present invention is concerned with the field of magnetic switches. In particular, the invention is concerned with a magnetic switch apparatus that detects relative movement between first and second members and defeats attempted external magnetic manipulation of the apparatus.
2. Description of the Prior Art
Prior art security alarm systems use magnetic switches attached to doors and windows and integrated with the system for detecting unauthorized opening indicating an intruder. One common type of magnetic switch is a so-called reed switch. This type of switch is subject to manipulation by an external magnet. That is, an intruder can use a magnet to hold the read switch closed (or open depending upon the control scheme) and thereby open a door or window without triggering the alarm system.


The present invention is a system and method for distributed, highly scalable, wide area peer-to-peer network data storage. The functionally equivalent servers in the system are divided into groups. Each server maintains a dynamic list which is polled to determine the availability of the closest neighbor servers. Each server is switched between the groups of servers to optimize network connectivity parameters. Data and directory files are divided into a plurality of pieces which are stored on different servers. Files are uniformly and independently named, utilizing a tree with a common root, logical pathways, and unique file identifiers. When a server receives a client request for file system access, the plurality of file pieces are collected and sent to the client server from the neighbor servers simultaneously in order to optimize bandwidth. Servers with maximum throughput capacity are utilized for highest transmission speed and reduced processing time.

1. Field of the Invention
The present invention pertains to distributed data storage; more particularly, the present invention describes a distributed, highly scalable, wide area peer-to-peer network data storage system and method.
2. Background of the Invention
The problem of data storage in a computer network appeared immediately after computers started to be connected to one another. The data storage problem has typically been solved by providing one of the computers with the necessary service, i.e., by organization of the file server. When one of the computers has an organized file server, the other computers in the network have software installed that provides the work using the files saved on the correspondent servers. For example, the data storage files could be copied locally; or, more conveniently, access to the network data storage files could be imitated if the data storage files are saved on a virtual hard disk. DOS software usable on IBM personal computers was developed in such a way. For IBM computers, the client software that was to be installed would provide a user with a so-called network drive, if the connection to the network and to the corresponding file server was successful. Physically, network data storage files were located on the remote file server, but for the programs running on the client computer, they appeared to the user as if they were on local servers (Beheler 1987).
The foregoing system for providing access to the stored data implies a separated file server and client computer server access model. This means that it appears to the user that there are separated roles in the network—the roles of client and server (Crowley 1997).
While workable, the data storage system described above has many disadvantages. For example, every data storage file being accessed "pseudo-locally" actually resides on a remote server. In case somebody tries to provide the stored file with shared access, (i.e., several clients have a chance to see the same file) the programs running on the client computer (not knowing about the data storage scheme) can start writing in the same file. Writing in the same file can lead to content errors.
The next problem is that the data storage file itself, being situated on only one server (and more importantly, on one hard disk), cannot be accessed in case of failures in the data storage file server equipment, network problems, or server software failures (i.e., many "failure points" appear, which means "no access" to the data). Such inability to access data even appears in case of workable server equipment when a computer user must reboot an operating system. When rebooting a data storage file, access service becomes unavailable for the clients, which means a break in use again.
One of the solutions to the problem of accessibility to data storage files is to use the clusterization principle. The best-known data storage solution was implemented in the platform developed by Digital Equipment (DEC) company. The clusterization principle was based on the creation of a special hard disk array that could hold data and be connected to several processor units (computers) (Davis). In clusterization, sharing access to a data storage file was done by using special equipment, and not only by the separated computer.
This use of special equipment enabled the full interchangeability of all the processor units. The equipment that managed the clusterization support was of minor complexity, and therefore had higher reliability when compared with the separate computer. Particularly, it meant the absence of the clusterization process support software and the associated mistakes. Nevertheless, the special client software was to be installed into the operating systems of the client computers. Clusterization solved the problem of computers' interchangeability and the computer's independence of the services to which any client computer had access. Nevertheless, the equipment failure of clusterization hardware led to the problem of service unavailability.
More problems appear if the server and its data storage services are separated by distance and are connected via the internet. The typical example is a single server with data storage files, which gains access to the data storage services via special network protocols, such as the World Wide Web service protocol called http (Network Working Group). Such network protocols are specifically used in a distributed client-server network that is not as close as the local network described above.
Another Internet service feature is the necessity to service a great number of client computers trying to access necessary data. The number of client computers can be so large that the server itself can become inaccessible when trying to respond to the client computers' requests for data (due to the insufficient network throughput capacity or server's inability to answer every request). That is why it is clear that the approach with one stand-alone server (and even a group of servers located in one place) and client computers connected via the Internet leads to failures caused by the distance between the server and the client.
Therefore, the optimal situation for a client computer is a service or server located in the network closest to the client computer. Because of the large number of client computers, it is clear that it is necessary to have a distributed set of similar servers over the Internet and to choose the closest servers among them.
Such a solution assures a symmetry of service for each client computer, and therefore the same data accessibility for all servers, provided that appropriate connections to the client computers exist. The easiest way to solve this problem is the simple doubling of the data on each server and then providing fully symmetrical service, independent of the client computer and the location it requests to obtain the service (U.S. Pat. No. 6,092,178). Such a decision at the same time presents many additional problems, such as data synchronization.
To provide such a service, dedicated distributed data storage was developed that made it possible to access data storage files. In a distributed data storage system, the distribution of the service means actually running the server processes of the operational systems at the corresponding network unit (at the server) (Davis and Pfister 1998). Such an approach helps to minimize access time and, at the same time, the problem of channel throughput between servers and the client computer.
Simultaneously, a distributed data storage system helps resolve the situation where computational power for the only computer is insufficient to perform all requests because a greater number of computers try to get service at the same time. Even in case of non-parallel request servicing, a distributed data storage system reduces the load on any server because the requests are distributed among the servers available. In addition, the level of resistance to failure grows. If the server becomes unavailable, the client computer can switch to another server and get the same service (determined by the symmetry range of the system servers) (Pfister 1998).
A distributed service must have a distributed data storage system, as the range of client services is usually based on this data.
To implement such distributed storage of data, it is necessary to develop data distribution and data storage algorithms. These algorithms must provide optimal data storage with respect to contents and resource utilization so that they provide the same contents on different servers based on the level of server symmetry.
Presently, these solutions typically use very complicated algorithms to access stored data. Data full duplex (mirroring) is used when every unit of the network has the full copy of the stored data files. For example, Internet FTP server mirror systems use this approach (U.S. Pat. Nos. 5,835,911, 5,434,994, 5,155,847, and 5,742,792).
A general network file system (for example, UNIX NFS system developed by Sun Microsystems, Inc. (Chet 1994) usually means the separated server and the client computer know what server to be connected to. Such general network file systems are usually intended for use with a minimum of separated servers.
Network distributed file systems are arranged in a more complicated way. They generally allow working in a shared uniform namespace whether a specific file server is accessible or not. Namespace is a collection of unique names, where name is an arbitrary identifier, usually an integer or a character string. Usually the term "name" is applied to such objects as files, directories, devices, computers, etc. For example, Open Software Foundation DFS (Distributed File System) is of such structure (Kumar 1991, Lebovitz 1992, Distributed File System, Rosenberry 1992, and Pfister 1998). Its namespace hierarchy stems from a shared point, i.e., root, of a file system. Nevertheless, every DFS name corresponds to a specific file server. Its loss entails disappearance of access to certain files. As this takes place, files get split apart. To make them more accessible, a program finds the way inside the namespace and recognizes the server wanted. Thus, there exists a potential interchangeability of files, but, even if properly organized, fault-tolerance level of the system is not higher than usual.
Another approach is the hierarchical system of file naming, combined with local data caching on a client server. Transarc Corporation (now IBM Transarc Labs) AFS (Campbell 1997) and Coda (Braam 1998 and Satyanarayanan 1989) systems use a hierarchical file naming system. To optimize data access, these systems cache data on the client side using cache to reduce the number of requests to the server. The AFS server broadcasts every request on the file (even on the one situated in cache) to the server data storage file, and only after getting the information that the data storage file has not changed since being copied into a local cache, the system provides access to it. If there is no connection with the data storage file server, the AFS system doesn't usually make it possible to use the data storage file. This can provide a Coda system by taking into account the fact that the files usually don't change and access is not waiting for connection with the file server.
Such an approach is more resistant to failures compared with several dedicated servers, which must be online all the time. Nevertheless, such an approach can lead to problems if several clients working with the same file simultaneously make concurrent changes that can lead to incorrect work in the future. Both approaches imply that the file is saved in cache, which means that there are many copies of the different file modifications in the network. The presence of many copies of different file modifications complicates file system serviceability control, i.e., data coherence. Moreover, these approaches imply that the access to the files that are not in cache will be possible only after their full extract to this cache. Access to files not in cache means that the support of the server system where different data is stored on different servers can lead to access problems in the case where connection to the server is lost.
The other method of distributed file access is the distribution not of the file but of the determination of distributed blocks' storage upon which the file system itself is built. The main problem with such a method is the necessity to place constant locks on the blocks where the internal (usually directory) information is stored due to concurrent access to them.
Another method is to use the approach similar to the one used in a RAID redundant data storage system. The RAID redundant data storage system makes it possible, with little redundancy, to access data even when one of the servers or hard disks becomes inaccessible. This particular method is called Level 5 RAID (Pfister 1998) and is used widely to increase the reliability of a disk array. The Level 5 RAID method was used for the so-called "serverless file system" built at the University of California at Berkeley (Anderson 1995), where the system did not have just one separated file system; rather, it had a group of them. Nevertheless, such realization isn't very flexible and is used for tightly coupled networks. Besides, the system allowed no use of servers with unequal efficiency and connection quality, as data accessibility depended on access to all of the servers, whether they were overloaded or not (with the exception of one with data parity recording). It simply is not suitable for data storage over the Internet.
What is needed is a system and method for distributed network data storage which minimizes content errors, access time and system failures. Such a system and method should maximize reliability, accessibility, and uniformity of data stored within the system. Additionally, there is a need for a method which provides a high degree of data coherence and synchronization, data storage flexibility, and maximum channel throughput and serviceability.

Distributed network data storage system and method


A signal discrimination device using a neural network for discriminating input signals such as radar reception signals includes an adaptive code generator means for generating codes for representing the discrimination categories. The distances between the codes for closely related categories are smaller than the distances between the codes for remotely related categories. During the learning stage, the neural network is trained to output the codes for respective inputs. The discrimination result judgment means determines the categories by comparing the outputs of the neural network and the codes for the respective categories.

This invention relates to signal discrimination devices for discriminating input signals, such as radar reception signals, by means of neural networks.
It is an important technical problem to discriminate the species of an object from the radar reception signals. The values which are representative of certain features of the observed object are calculated, and, on the basis of these values, the observed object is discriminated into classes or categories, such as the categories of the surface of the earth, the surface of the sea, and a form of an airplane.
In the case of the conventional signal discrimination devices using neural networks, the codes for representing the discrimination categories are usually determined without any reference to the values of the parameters representing the categories.
For example, G. Vrckovnik, C. R. Carter, S. Haykin: "Radial Basis Function Classification of Impulse Radar Waveforms", Proceedings of International Joint Conference on Neural Networks, Vol. 1, pp. 45 through 50, San Diego, 1990 (referred to hereinafter as article (1)) shows a discrimination method using a neural network by which radar waveforms from asphalt covered bridge decks are classified into three categories: two-lift asphalt over concrete over rebars (2ACR); two-lift asphalt over a waterproofing membrane over concrete over rebars (2AMCR); and three-lift asphalt over concrete over rebars (3ACR).
FIG. 5 is a block diagram showing the structure of a conventional signal discrimination device using a neural network. FIG. 6 is a diagram showing the structure of the neural network. FIG. 7 is a diagram showing the relationship of the inputs and an output component of the neural network. FIG. 8 is a flowchart showing the procedure by which the codes for respective categories are generated in the code generator means of FIG. 5. FIG. 9 is a flowchart showing the procedure by which the discrimination result judgment means of FIG. 5 discriminates the categories in response to the outputs of the neural network. The structures and the procedures shown in these figures are those inferred from the disclosure of the above article (1).
As shown in FIG. 5, the input data for discrimination 2 and the input data for learning 3 are coupled selectively to the neural network 8 via a learning/discrimination change-over switch 7. The output of a code generator means 11 is selectively coupled to the neural network 8 and the discrimination result judgment means 9 via a switch interlocked with the learning/discrimination change-over switch 7. The output of the discrimination result judgment means 9 are stored in a data file for discrimination result judgement 4.
As shown in FIG. 6, the neural network 8 includes: an input layer 22 consisting of a plurality of input nodes or input elements; an intermediate layer 23 consisting of intermediate nodes 21 provided with respective weights; and an output layer 24 consisting of output elements 20.
The output (0) 31 of each output node 28 of the neural network 8 is generated as shown in FIG. 7. Namely, a plurality of input data, i.sub.1, i.sub.2, i.sub.3, - - - , i.sub.M applied to the input nodes 27 are weighted by the respective weights 29, w.sub.1, w.sub.2, w.sub.3, - - - , w.sub.M. The weighted sum of inputs: ##EQU1## is calculated by the summation means 25.
Then, the output data 31 is calculated by means of the conversion function 26: and is output from each output node 28.
Next, the operation of the signal discrimination device of FIGS. 5 through 7 is described. It is assumed that the inputs are classified into three categories: (1) two-lift asphalt over a waterproofing membrane over concrete over rebars (2AMCR); (2) two-lift asphalt over concrete over rebars (2ACR); and (3) three-lift asphalt over concrete over rebars (3ACR).
First, the code generator means 11 determines the codes of the respective categories as shown in TABLE 1 in accordance with the procedure shown in FIG. 8.
TABLE 1 ______________________________________ category code ______________________________________ 2AMCR 100 3ACR 010 2ACR 001 ______________________________________
At step S60 in FIG. 8, the code length L of the output of the neural network 8 is set equal to the number N of classification categories into which the inputs are to be classified via the neural network 8. Then, at step S61, the components C.sub.ij (where j ranges from 1 to the code length L) of the code C.sub.i for the ith category are set by: ##EQU2##
Thus, the codes for the respective categories are determined as shown in TABLE 1. Each code is determined under the assumption that only one of its components takes the value 1.
Next, the learning/discrimination change-over switch 7 is switched to the learning side to train the neural network 8. By means of this learning or training procedure, the neural network 8 learns to output the codes as shown in TABLE 1 for respective categories in response to the input data for learning. The neural network 8 receives sets of input data for learning 3 and the codes corresponding thereto as shown in TABLE 1 generated by the code generator means 11. (Each set of the input data for learning 3 consists of a number of sample values composing a radar reception signal waveform.) In response to the sets of the input data for learning 3 and the codes corresponding thereto, the neural network 8 modifies the weights of the intermediate nodes 21 in accordance with the well-known error back propagation algorithm or the radial basis function algorithm described in the above article (1). After the modification of the weights of the intermediate nodes 21 is completed, the neural network 8 is trained to output the codes C.sub.i as shown in TABLE 1 for the respective categories in response to the input data for learning 3.
When the learning is completed, the learning/discrimination change-over switch 7 is switched to the discrimination side to discriminate or classify each set of input data for discrimination 2 into the categories (1) through (3). (Each set of the input data for discrimination 2 consists of a number of samples of a radar reception signal waveform) thus, in response to the input data for discrimination 2, the neural network 8 outputs signals each consisting of three values approximately equal to the codes C.sub.i for the respective categories. These outputs of the neural network 8 are generated via the data conversion shown in FIG. 7. The discrimination result judgment means 9 receives the output codes of the neural network 8 and the codes generated by the code generator means 11, and determines the category or classification of each set of the input data for discrimination 2.
FIG. 9 is a flowchart showing the procedure by which the discrimination result judgment means of FIG. 5 discriminates the categories in response to the outputs of the neural network. At step S50, a neural network output O (consisting of three values) and the codes C.sub.i (i=1 through N) for respective categories as shown in TABLE 1 are input to the discrimination result judgment means 9. Next, at step S51, the discrimination result judgment means 9 determines the distance D.sub.i (i=1 through N): ##EQU3## where O.sub.j is the output value of the jth element of the output elements 20 of the neural network 8, C.sub.ij is the jth component of the C.sub.i.
Then, at step S52, the discrimination result judgment means 9 determines the minimum D.sub.I among the D.sub.i (i=1 through N). Further, at step S53, the ith category is identified as the category to which the input data for discrimination 2 is classified.
The above conventional signal discrimination device has the following disadvantage. Namely, the distances between the codes for respective categories are determined without any relation to the degrees of affinity between the categories.
FIG. 10 is a diagram showing the distances between the codes for respective categories for the signal discrimination device of FIG. 5. The codes of length L can be represented as points in L dimensional Euclidean space. Thus, in FIG. 10, the codes C.sub.i (i=1 through 3) for three categories are represented as points 35, 36, and 37, respectively, in the 3-dimensional Euclidean space. The distances AB, AC, and BC between the categories A and B, between the categories A and C, and between the categories B and C, respectively, are equal to each other, although, for example, the relation between the categories B and C is less close than the relations between the categories A and B or between the categories A and C, and hence the discrimination or classification error is more grave between the categories B and C than between the categories A and B or the categories A and C. Thus, the probability of an occurrence of a grave classification error (between the categories B and C) is as high as the probability of an occurrence of less grave classification errors (between the categories A and B or between the categories A and C). Classification errors generally occur at random (with equal probability between the categories B and C and between the categories A and B or between the categories A and C), due to the noises in the input data for discrimination 2 or failures of elements within the neural network 8.

Signal discrimination device using neural network


Embodiments of an invention for soft dark bit masking are disclosed. In one embodiment, an apparatus includes a basic physically unclonable function (PUF) cell, a load, and a masking circuit. The load is selectively connectable to the basic PUF cell to determine whether the basic PUF cell is unstable. The masking circuit is to mask the output of the basic PUF cell if the basic PUF cell is determined to be unstable. Embodiments of the invention also include mechanisms to reinforce the stability of stable cells, while further destabilizing unstable cells.

1. Field
The present disclosure pertains to the field of information processing, and more particularly, to the field of security in information processing systems.
2. Description of Related Art
Unique, secret keys are used by information processing systems to encrypt confidential information, provide proof of identity, and many other purposes. These keys may be derived from physically unclonable functions that generate random values based on the variability inherent in integrated circuit fabrication.

Soft dark bit masking with integrated load modulation and burn-in induced destabilization for physically unclonable function keys


A delivery system for a self-expanding medical device is provided. The delivery system includes an outer sheath that radially restrains the medical device. An inner catheter is disposed within the outer sheath. The inner catheter is a composite structure with an inner layer adhered to the inner diameter of a closed coil wire. The inner catheter has a wave-like pattern along the outer surface that is exposed to the inner surface of the outer sheath.

The present invention relates generally to medical devices and more particularly to delivery systems for medical devices.
Intraluminal medical devices are used by physicians to treat numerous conditions using minimally invasive procedures. Examples of intraluminal medical devices include stents, stent-grafts, filters, valves, etc. One type of intraluminal medical device that has become especially common is self-expanding stents. Typically, self-expanding medical devices, including stents, are made from an elastic structure that may be compressed into a low profile state that can be passed through vessels in a patient with minimal trauma. Once at the desired treatment site, the self-expanding medical device is released and self-expands like a spring until it contacts a tissue wall which prevents further expansion. Common materials that are used in self-expanding medical devices include nitinol and stainless steel, although other materials are also possible.
Self-expanding stents are used to treat various organs, such as the vascular system, colon, biliary tract, urinary tract, esophagus, trachea and the like. For example, stents are commonly used to treat blockages, occlusions, narrowing ailments and other similar problems that restrict flow through a passageway. One area where stents are commonly used for treatment involves implanting an endovascular stent into the vascular system in order to improve or maintain blood flow through narrowed arteries. However, stents are also used in other treatments as well, such as the treatment of aneurysms. Stents have been shown to be useful in treating various vessels throughout the vascular system, including both coronary vessels and peripheral vessels (e.g., carotid, brachial, renal, iliac and femoral). In addition, stents have been used in other body vessels as well, such as the digestive tract.
One type of delivery system for intraluminal medical devices includes an inner catheter and an outer sheath attached to a handle arrangement. One portion of the handle is typically connected to the inner catheter and another portion of the handle is typically connected to the outer sheath. The inner catheter extends coaxially through the outer sheath, and the two portions of the handle are arranged to longitudinally pull the outer sheath relative to the inner catheter. Thus, when the distal end of the delivery system is positioned within the patient's body at the intended treatment site, the physician actuates the handle outside the patient's body by moving the two portions relative to each other so that the outer sheath is withdrawn over the medical device and inner catheter. In the case of self-expanding medical devices, like stents, the outer sheath also serves to radially restrain the device in the compressed state until the outer sheath is withdrawn. As the outer sheath is withdrawn, the medical device is released in the body at the treatment site, and in the case of a self-expanding stent, the stent expands outward away from the inner catheter and presses against the vessel wall. Although the outer sheath is usually withdrawn by pulling the outer sheath proximally relative to the inner catheter, it may also be possible to withdraw the outer sheath by pushing the inner catheter distally relative to the outer sheath. After the medical device has been fully released from the delivery system, the handle may then be pulled by the physician to withdraw the inner catheter and outer sheath from the patient's body, while leaving the medical device implanted in the body.
Precise placement of intraluminal medical devices is a concern in most medical procedures. One problem that can contribute to imprecise placement of intraluminal medical devices is deflection of the delivery system during deployment. This can be a particular problem in the deployment of self-expanding medical devices, like stents, because the medical device presses outward against the inner surface of the outer sheath prior to deployment. When the outer sheath is withdrawn, the outward pressure exerted by the medical device creates friction between the medical device and the outer sheath. Since the medical device is typically prevented from moving proximally with the outer sheath by a stop attached to the inner catheter, the frictional force between the medical device and the outer sheath causes the outer sheath to be in tension and the inner catheter to be in compression. This can cause the inner catheter to contract in length due to the compressive force. In addition, the inner catheter can buckle, or snake, within the outer sheath. Both of these responses can cause the distal end of the inner catheter, and thus the medical device itself, to move proximally from the intended treatment site. Although the contraction and buckling may decrease somewhat as the outer sheath begins to withdraw from the medical device due to the release of some of the frictional force, the distal end of the inner catheter may not completely return to the intended treatment site when the medical device is initially released and implants within the patient's body. Moreover, the stent and/or inner catheter can build up sufficient spring force due to the contraction of the inner catheter and the stent to cause the stent to jump distally once the static friction is released. With medical devices that cause high frictional loads against the outer sheath, like drug coated stents, covered stents and particularly long stents, the initial deflection of the delivery system and subsequent distal movement due to the release of friction can make it difficult for a physician to predict the exact location where the medical device will be released in a patient's body.
Accordingly, the inventor believes it would be desirable to provide an improved delivery system for intraluminal medical devices.

Inner catheter for a self-expanding medical device delivery system with a closed coil wire


A change-gear transmission having an input shaft, a main shaft having at least one main shaft gear, a plurality of countershafts spanning between the input shaft and main shaft gear, and gear synchronizers between selectable gears. The bore of main shaft gears have a minimal radial clearance fit with its mating parts to prevent gear synchronizer wear, while the meshing between the input shaft gears and countershaft gears is equally distributed using a means to equalize the torque transfer between countershafts. The countershafts are rotatably supported and displace axially between bearing or bushing supports, while the meshed gears comprise a helical gear tooth arrangement to create axial load on the countershaft if excessive and uneven load is sensed in one countershaft over another. This presents a new and unique countershaft meshing design that allows multiple countershafts to achieve equal load sharing while permitting gear synchronizers use on the main shaft.

1. Field of the Invention
The present invention relates to transmission assemblies, gear change devices and dynamic components utilized for transferring power and torque. More specifically, the present invention pertains to an improved transmission assembly that utilizes a plurality of axially floating countershafts that adjust to equally accept input load for preventing excessive wear, improving component lifespan and reducing potential harmonics due to unequal load-sharing between transmission countershaft members. The present invention further provides equal load-share while incorporating gear change synchronizers to facilitate smooth gear changes while preventing excessive wearing of these components due to radial positioning mismatch or slack.
Automotive and other vehicle transmissions are well known for transmitting and transforming input power from a rotary power source into one that is suitable for desired output, whether driving the wheels of the vehicle or operating a mechanical component in a manufacturing process. The goal is generally to create an efficient and reliable dynamic assembly that can accept considerable loads without occupying undue space, consuming energy or reducing the effectiveness of the overall process. To effectively transmit high levels torque, most transmissions utilize intermediate shafts to split the torque into different paths using smaller elements, which permit designers to reduce the overall size of the individual components over a design utilizing a single transmission pathway subjected to the entirety of the torque input load. By splitting the torque, the structural requirements of the components are reduced, where otherwise a single shaft would require significant load carrying capacity for the same end goal. The use of several countershafts, in particular, splits the load between several gear components and intermediate shafts, which increases the number of components in the assembly but can significantly reduce their individual size. Thus efficient placement and spacing of components allows the overall transmission to be reduced in size when compared to the size requirements of larger transmission components using fewer or no load splits.
The primary concern related to separating a transmission input load and distributing it to several intermediate elements is the potential for imbalanced load transfer and uneven contact between meshed gear sets. A perfectly meshed set of components can be designed, but the reality of design tolerances and manufacturing and assembly considerations inevitably leads to mismatches in contact between these components, which are further exacerbated by their dynamic nature. Unequal contact and unequal load share can result in excessive wear, reduced component life, premature failure of the system and harmonics that threaten the operation of the transmission. Uneven wear and complete failure from this unequal load share creates an obstacle to efficiently separating input load into intermediaries without compromising longevity.
The present invention is provided as an improved transmission assembly having countershafts that are capable of utilizing gear synchronizers and further for allowing equal distribution of load between an input shaft and a plurality of countershafts. Most conventional twin and multiple countershaft transmissions achieve equal load sharing between countershafts by allowing free radial movement of main shaft and main shaft gears to account for the imbalance. There are a lot of advantages to this design and it has been shown to be highly effective and widely implemented for vehicle transmission assemblies; however the main drawback to this design is the inability to utilize gear synchronizers, as the radial movement of the gears causes nonuniform contact and increased friction between the synchronizer ring and the cone surface of the main shaft gears when shifting. This friction results in reduced reliability and useful life of the synchronizer, as the friction rapidly creates wear and premature failure. It will be appreciated then that the ability to utilize synchronizers in a transmission having radially floating members precluded, and therefore the overall shifting quality is reduced for the user during gear transitions.
Specifically, the present invention provides a transmission having a plurality of countershafts that are fixed radially and allowed to float axially to account for torque mismatch between complementary countershafts when countershaft gears are in contact with main shaft gear. The countershafts are adapted to displace axially in either direction to account for uneven load transfer, wherein the countershaft gears are helical gears having the same helix hand. When shifting to one gear, the constant gear and ongoing engaged gear on countershaft will automatically self-adapt or self-adjust while balancing any axial load imbalance between the countershafts. The constant gear set and ongoing engaged gear set will then mesh each other to achieve equal load sharing, as the helical gear teeth transform the torque into an axial load, which is balanced between the set of countershafts.
2. Description of the Prior Art
Many transmission systems and gear change mechanisms have been disclosed in the prior art that relate to equal load share between transmission countershaft and main shaft members. These include devices that have been patented and published in patent application publications, and generally relate to radially floating members or designs that include a balancing means. The forgoing is a list of devices deemed most relevant to the present disclosure, which are herein described for the purposes of highlighting and differentiating the unique aspects of the present invention, and further highlighting the drawbacks existing in the prior art.
Specifically, U.S. Pat. No. 4,640,145 to Vandervoort discloses a multiple countershaft transmission assembly that is designed to reduce to the overall noise signature of the device during operation, as a gear tooth meshing and surface contact noises is mitigated through its unique design. Specifically, the assembly comprises a gear change transmission having multiple countershaft assemblies, wherein an input gear is constantly engaged with a countershaft gear. The input gear is provided having a gear tooth pitch that is not evenly divisible by the number of countershafts, whereby there is a time interval between gear meshing between the input and countershaft to reduce noise generation. The contact noise is not amplified but rather offset between countershafts. The Vandervoort transmission assembly, while providing a unique, lower noise transmission does not include synchronizer and a means of offsetting countershaft engagement with respect to an input shaft to reduce overall input and output shaft displacement, as provided for in the present invention.
Another such device is U.S. Pat. No. 4,807,493 to Loeffler, which discloses a twin countershaft transmission assembly having a floating main shaft having no internal or external bearings or other support device near its adjacent ends, whereby the main shaft is supported by a gears carrying the torque thereto. This arrangement provides a true torque split between countershafts, as the main shaft is able to accommodate relative movement between the shafts by not being constrained by a bearing or support device. The Loeffler device discloses a transmission having a self-aligning main shaft, while the present invention provides an even torque split and reduced component wear by allowing lateral displacement of the countershafts along their length to accommodate relative input and output shaft movement.
U.S. Pat. No. 3,611,823 to Richards discloses a similarly designed transmission assembly as that of Loeffler, wherein a transmission having a floating input or main drive gear is provided that freely displaces in an axial direction relative to both the input shaft and to the transmission main shaft. A coupling member linking the input shaft and the input gear permits axial rocking movement of the input gear relative to the input shaft to maintain alignment and identically rotate countershafts at substantially identical speeds. The Richards device, similar to the Loeffler device, fails to disclose axially adjusting countershafts that accept input from the input shaft without creating stress concentrations, binding, or other wearing situations otherwise created when the input and output shaft displace radially and unequally distribute torque to the countershafts. The present invention provides an axially adjusting set of countershafts to maintain even contact between the input and all meshed countershafts within the transmission assembly.
U.S. Pat. No. 6,073,506 to Wireman discloses a multiple countershaft transmission that includes at least two countershafts having sufficient gear tooth backlash such that the countershafts not presently transmitting drive torque due to minor assembly imperfections do not to impede substantially equal load-sharing of those countershafts transmitting drive torque. In this way, the Wireman device includes a means of maintaining equal load-sharing between countershafts in spite of assembly and manufacturing imperfections that cause unequal contacts within the transmission assembly. The backlash provides sufficient clearance for imperfections between a plurality of meshed gears, which are inevitably unequally in their contact between meshed pairs and lead to unequal torque distribution. The Wireman device intends to include greater tolerances between gear sets, as opposed to the present invention that provides an axially displacing countershaft design that accommodates unequal contact intervals and unequal load-sharing from a driving gear to the countershaft gears.
U.S. Pat. No. 4,709,590 to Richards discloses a change speed gear transmission having a plurality of spaced countershafts and countershaft gears thereon, a driving and driven means for rotating the countershafts, a central shaft and gears and a clutch means. The gears of the transmission are double-helical gears that assure that the load transmitting gear will tend to automatically self-align into a position where each countershaft transmits substantially equal torque load. Similar to the Wireman device, the Richards device includes a new gear design that attempts to solve unequal load sharing. The present invention provides axially adjustable countershaft gears to account for unequal load sharing between several countershafts from a driving input.
Finally, U.S. Pat. No. 6,374,689 to Morrow discloses a load balancing gear set apparatus that utilizes a balancing mechanism to deliver equal and optimum power to intermediate shafts within the transmission. The transmission includes a power input and pairs of intermediate elements that engage using helical gear sets. To obtain even power distribution between intermediate elements from the input, a mechanical balancing element comprising a lever mechanism mounted to a pivot point is provided, wherein the lever mechanism is permitted a rocking motion that displaces the intermediate shafts in the presence of load imbalance. Imbalanced loads in helical gears create axial loads that will pivot the lever mechanism into an equilibrium position. This design, while simple and effective for balancing countershaft transmission elements, requires a common lever mechanism to operate, and may not function with many countershafts beyond a simple pair. The present invention is adapted to allow free axial movement of each countershaft to balance these loads, wherein each countershaft is free to move independently based on input load displacing the countershafts into a state of equal load sharing.
The present invention provides an improved gear change mechanism and transmission that incorporates axially floating countershafts to account for load mismatch and further allow for the use of synchronizers for smooth gear transitions. It is submitted that the present invention is substantially divergent in design elements from the prior art, and consequently it is clear that there is a need in the art for an improvement to existing countershaft transmission devices. In this regard the instant invention substantially fulfills these needs.

Gear change transmission having axially adjusting countershafts


A Magnetic Tunnel Junction (MJT) Ternary Content Addressable Memory (TCAM) employing six transistors and exhibiting reduced standby leakage and improved area-efficiency. In the proposed TCAM, data can be written to the MJT devices by conventional current induced magnetization techniques and by controlling the source line, thereby eliminating the need for external writing circuitry.

Field of the Invention
This invention relates to content addressable memories. More specifically, the invention provides a magnetic tunnel junction (MTJ) based ternary content addressable memory (TCAM).
Brief Description of the Prior Art
Magnetic Tunnel Junction (MTJ) is a spintronic device which stores data in the form of spin of an electron, unlike a static Complementary Metal-Oxide-Semiconductor (CMOS) memory cell, which stores data in the form of electric potential. An MJT device consists of three layers—a layer of magnetic oxide sandwiched between two layers of magnetic material. Data is stored in the form of magnetization in the two magnetic material layers. A logic '0' is stored when the two magnetic layers are magnetized in the same direction and a logic '1' is stored when the two magnetic layers are magnetized in the opposite direction. FIG. 1A illustrates an MTJ device configuration in parallel and antiparallel states.
Pinned Layer (PL) magnetization exhibits a fixed magnetization, whereas Free Layer (FL) magnetization can be polarized parallel or anti-parallel with respect to the PL. In this context, it should be noted that the resistance of MTJ is high when PL and FL are in antiparallel configuration, whereas the resistance of MJT is low when PL an FL are parallel to each other. The value written to the MTJ depends on the direction and the strength of the charge current. The minimum current required to flip the state of the MTJ is called the critical current. FIG. 1B illustrates the directions charge current to write '1' and '0' to an MTJ device.
Tunnel Magneto Resistance (TMR) is the ratio of electrical resistances of the MTJ structure in parallel and antiparallel polarization states of FL relative to PL magnetization. If RH is the MTJ resistance in an antiparallel state and RL is the MTJ resistance in a parallel state, the TMR is defined as
  TMR  =                    R        H            -              R        L                    R      L
Content Addressable Memory (CAM) is widely used in pattern matching, internet data processing, packet forwarding, for tag bits storage in a processor cache, for associative memory and in many other fields where searching a specific pattern of data is a major operation. The special functionality of the content search in CAM requires a comparison circuitry integrated with the memory cell. The required comparator, in addition to the memory element itself, adds area and power overhead in CAMs.
CAMs can be divided into two categories depending on the number of states that can be stored in the memory cell, namely: binary CAM (BCAM) and ternary CAM (TCAM). BCAM stores a binary bit, namely '0' and '1', whereas TCAM can store three possible values, namely '1', '0', and 'don't care' (X). CAMs can be further categorized into two topologies, namely NOR and NAND type (see FIGS. 1C-1D). The stored bits are compared with the data on the search line (SL) and its complement (\SL) by XOR operation with the transistor network M1, M2, M3, and M4. To store data in a TCAM cell having a NOR-type architecture, data bit and the complement are stored in two SRAM cells.
The 'don't care' bit can be realized by storing '1' in both SRAM cells, i.e., D=\D=1. In the case of a match, both SL-D and \SL-\D paths are disconnected, and the match line remains precharged. In the case of miss, either of the SL-D or \SL-\D connect ML to ground, which discharges the precharged ML.
In a NAND-type architecture, TCAM cells are connected in series. Data bit D and \D are derived from a single SRAM cell, unlike two SRAM cells in a NOR-type TCAM. The stored bit is masked by using a mask bit (M) in a parallel SRAM cell.
In case of match, the precharged ML is connected to ground by series TCAM cells of the word by turning the NMOS transistor M1 'ON'. Storing the mask bit as '1' enables transistor M2, despite match or miss, which implements 'don't care' functionality. CMOS TCAM uses two SRAM cells, thereby doubling the area overhead, compared to conventional SRAM cells.
However, conventional CAMs suffer from area, power, and speed limitations. As it pertains to TCAM, the need to store and match a 'don't care' matching state requires two storage bits, which further worsens the area overhead. CMOS CAM is power hungry due to power consumed in match line (ML), search line, and leakage of the bit cell. In nanometer technologies, leakage power constitutes a major portion of the total power consumed in CAM memory. Non-volatile technologies, which are more area efficient than status random-access memory (SRAM) and can provide zero leakage, are attractive in such a scenario. However, continued improvement of TCAM is needed.
Accordingly, what is needed is improved area efficiency and non-volatility using MTJ-based TCAM for on-chip CAM applications. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention. Applicant in no way disclaims these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.

Magnetic tunnel junction ternary content addressable memory