Showing papers by "Mitsubishi Electric published in 1994"

Linear cryptanalysis method for DES cipher

Abstract: We introduce a new method for cryptanalysis of DES cipher, which is essentially a known-plaintext attack. As a result, it is possible to break 8-round DES cipher with 221 known-plaintexts and 16-round DES cipher with 247 known-plaintexts, respectively. Moreover, this method is applicable to an only-ciphertext attack in certain situations. For example, if plaintexts consist of natural English sentences represented by ASCII codes, 8-round DES cipher is breakable with 229 ciphertexts only.

The First Experimental Cryptanalysis of the Data Encryption Standard

Abstract: This paper describes an improved version of linear cryptanalysis and its application to the first, successful computer experiment in breaking the full 16-round DES. The scenario is a known-plaintext attack based on two new linear approximate equations, each of which provides candidates for 13 secret key bits with negligible memory. Moreover, reliability of the key candidates is taken into consideration, which increases the success rate. As a result, the full 16-round DES is breakable with high success probability if 243 random plaintexts and their ciphertexts are available. The author carried out the first experimental attack using twelve computers to confirm this: he finally reached all of the 56 secret, key bits in fifty days, out of which forty days were spent for generating plaintexts and their ciphertexts and only ten days were spent for the actual key search.

On correlation between the order of S-boxes and the strength of DES

Abstract: This paper introduces a practical algorithm for deriving the best differential characteristic and the best linear expression of DES. Its principle is based on a duality between differential cryptanalysis and linear cryptanalysis, and applicable to various block ciphers. Then using this program, we observe how the order of S-boxes affects the strength of DES. We show that the order of the S-boxes is well-arranged against differential cryptanalysis, though it is not the best choice. On the other hand, our experimental results indicate that it is a very weak choice in regard to linear cryptanalysis. In other words, DES can be strengthened by just rearranging the order of the S-boxes.

Real-time omnidirectional image sensor (COPIS) for vision-guided navigation

Abstract: Describes a conic projection image sensor (COPIS) and its application: navigating a mobile robot in a manner that avoids collisions with objects approaching from any direction. The COPIS system acquires an omnidirectional view around the robot, in real-time, with use of a conic mirror. Based on the assumption of constant linear motion of the robot and objects, the objects moving along collision paths are detected by monitoring azimuth changes. Confronted with such objects, the robot changes velocity to avoid collision and determines locations and velocities. >

Measurements of the proton elastic form factors for 1 <= Q2 <= 3 (GeV/c)2 at SLAC.

Abstract: We report measurements of the proton form factors [ital G][sub [ital E]][sup [ital p]] and [ital G][sub [ital M]][sup [ital p]] extracted from elastic scattering in the range 1[le][ital Q][sup 2][le]3 (GeV/[ital c])[sup 2] with total uncertainties [lt] 15% in [ital G][sub [ital E]][sup [ital p]] and [lt] 3% in [ital G][sub [ital M]][sup [ital p]]. Comparisons are made to theoretical models, including those based on perturbative QCD, vector-meson dominance, QCD sum rules, and diquark constituents in the proton. The results for [ital G][sub [ital E]][sup [ital p]] are somewhat larger than indicated by most theoretical parametrizations, and the ratios of the Pauli and Dirac form factors [ital Q][sup 2]([ital F][sub 2][sup [ital p]]/[ital F][sub 1][sup [ital p]]) are lower in value and demonstrate a weaker [ital Q][sup 2] dependence than those predictions. A global extraction of the elastic form factors from several experiments in the range 0.1 [lt] [ital Q][sup 2] [lt] 10 (GeV/[ital c])[sup 2] is also presented.

Contextual tagger utilizing deterministic finite state transducer

Abstract: A system for assigning part-of-speech tags to English text includes an improved contextual tagger which utilizes a deterministic finite state transducer to improve tagging speed such that large documents can have its sentences accurately tagged as to parts of speech to permit fast grammar checking, spell checking, information retrieval, text indexing and optical character recognition. The subject system performs by first acquiring a set of rules by examining a training corpus of tagged text. Then, these rules are transformed into a deterministic finite-state transducer through the utilization of non-deterministic transducers, a composer and a determiniser. In order to tag an input sentence, the sentence is initially tagged by first assigning each word in the sentence with its most likely part of speech tag regardless of the surrounding words in the sentences. The deterministic finite-state transducer is then applied on the resulting sequence of part of speech tags using the surrounding words and obtains the final part of speech tags. The Subject System requires an amount of time to compute the part-of-speech tags which is proportional to the number of words in the input sentence and which is independent of the number of rules it has applied.

An Alternative Conception of Tree-Adjoining Derivation

Abstract: The precise formulation of derivation for tree-adjoining grammars has important ramifications for a wide variety of uses of the formalism, from syntactic analysis to semantic interpretation and statistical language modeling. We argue that the definition of tree-adjoining derivation must be reformulated in order to manifest the proper linguistic dependencies in derivations. The particular proposal is both precisely characterizable through a definition of TAG derivations as equivalence classes of ordered derivation trees, and computationally operational, by virtue of a compilation to linear indexed grammars together with an efficient algorithm for recognition and parsing according to the compiled grammar.

An experimental analysis of DC excitation of transformers by geomagnetically induced currents

Abstract: DC excitation of transformers due to geomagnetically induced currents was studied by model experiments. First, differences in the DC excitation phenomenon due to the iron core structure were studied using three typical small-scale models. The results verified that single-phase three-legged cores were most susceptible and three-phase three-legged cores least susceptible to such excitation effects. Secondly, the local heating due to DC excitation was quantitatively assessed using large-scale core form and shell form models with the most susceptible single-phase three-legged cores. The results demonstrated that the maximum temperature rise was approximately 110/spl deg/C due to the GIC (200 A/3 phases). >

An SOI-DRAM with wide operating voltage range by CMOS/SIMOX technology

Abstract: For future ULSI DRAMs beyond the 256 Mb generation, several circuit techniques and memory cell structures have been proposed to meet the requirement of high performance at low voltage. These solutions frequently involve complicated processing steps and/or the ultimate limitations of current Si-MOS devices. DRAM on silicon on insulator (SOI) substrate is a more simple solution to the problem. Thin-film SOI structures with isolation by implanted oxygen (SIMOX) process are under investigation for SRAM and logic. A SOI-DRAM test device with 100 nm thick SOI film has been fabricated in 0.5 /spl mu/m CMOS/SIMOX technology. With this 64 kb SOI-DRAM the bit-line to memory cell capacitance ratio Cb/Cs is reduced by 25% compared with the reference bulk-Si DRAM, because of the decreased junction capacitance. RAS access time tRAC is 70 ns at 2.7 VVcc, as fast as the equivalent bulk-Si device at 4 VVcc. The clock timing in this DRAM is not optimized, so access time should improve with well-tuned clocks. The boosted-level generator with body-contact structure enhances the upper Vcc margin and the reduced body-effect of sense-amplifier transistors improves the lower Vcc margin. The SOI-DRAM has an operating Vcc range from 2.3 V to 4.0 V. >

Refrigerant circulating system

Abstract: The system uses a non-azeotropic mixture as refrigerant and comprises: a main refrigerant circuit connected by a compressor (1), a four-way valve (2), an outdoor heat-exchanger (3), a first throttling device (4a-c), a plurality of indoor heat-exchangers (5a-c), and a low-pressure receiver (6); a bypass circuit diverging from the discharge portion of the compressor (1) and extending through a composition detecting heat-exchanger (9) and a second throttling device (8) to the low-pressure side; an outdoor fan (7) associated with the outdoor heat-exchanger (3); a first temperature detector (103) to detect refrigerant temperature upstream of the second throttling device (9); a second temperature detector (104) to detect refrigerant temperature downstream of the second throttling device (8); a first pressure detector (102) to detect pressure downstream of the second throttling device (8); a third temperature detector (105a-c) to detect temperature in the main circuit between the first throttling device (4a-c) and the indoor heat-exchangers (5a-c); a fourth temperature detector (106a-c) to detect temperature at the low-pressure side; a second pressure detector (101) to detect the pressure at the high-pressure sides a device (21) for calculating the composition of the mixture refrigerant, a main controller (22) for controlling the speed of the compressor (1) ) and the speed of the fan (7) on the basis of the refrigerant composition and pressure; and a controller (23) for controlling the opening of the first throttling device (4a-c).

An alternative conception of tree-adjoining derivation

Abstract: The precise formulation of derivation for tree-adjoining grammars has important ramifications for a wide variety of uses of the formalism, from syntactic analysis to semantic interpretation and statistical language modeling We argue that the definition of tree-adjoining derivation must be reformulated in order to manifest the proper linguistic dependencies in derivations The particular proposal is both precisely characterizable through a definition of TAG derivations as equivalence classes of ordered derivation trees, and computationally operational, by virtue of a compilation to linear indexed grammars together with an efficient algorithm for recognition and parsing according to the compiled grammar

Computer network system and method for managing documents

Abstract: An electronic document management system converts documents into electronic images which can be sequentially routed to individual users in a network system. The network system includes at least two work nodes for processing the documents where one of the nodes is a data entry work node. The documents are subdivided into two or more subdivisions which are classified by subdivision type. The images are routed through the network system according to predefined routing schemes based on its subdivision type. The routing scheme for the documents includes at least one data entry node where data contained in the document is entered into a database. As the data is entered into the database, it is dynamically linked with its corresponding image which is also stored in the network.

System for correcting improper determiners

Abstract: In a grammar checking system which includes first tagging a sentence as to parts of speech, an improper determiner correction module detects improper referents of a noun phrase and suggests insertion of a determiner should one be necessary or the deletion of an improper determiner. To detect improper use of a determiner, parts of speech tags are utilized to characterize a sentence, thus to identify noun phrases by maximally matching a pattern that defines which sequences of parts of speech tags constitute valid noun phrases. This is accomplished by identifying the start of the noun phrase and its end to permit checking for either missing determiners, extraneous determiners, or lack of agreement in number for the constituents of the noun phrase. Once a noun phrase is found, the system tests to see if the noun is a head noun and thereafter if the head noun is a singular non-proper noun, whether the noun phrase contains a determiner, whether the noun phrase is a title, whether the head noun is a mass noun or whether the noun phrase is part of an idiom. The system also checks to see if the head noun is a proper noun and if so whether the noun phrase contains a determiner. Finally, if the noun phrase contains a determiner the system checks if the determiner agrees in number with the head noun. In this manner, both missing determiners, extraneous determiners and determiner noun number disagreement are detected and reported.

Dielectric Properties of (BaxSr1-x)TiO3 Thin Films Prepared by RF Sputtering for Dynamic Random Access Memory Application

Abstract: Dielectric properties of (Ba0.5Sr0.5)TiO3 and (Ba0.75Sr0.25)TiO3 thin films have been investigated, focusing on the effects of film structure and Ba/Sr compositions on the dielectric properties. Dielectric constant of the films increased with increasing grain size and with improvement in film crystallinity. For the 50-nm-thick films deposited at 660° C, the dielectric constant of 400 for the (Ba0.5Sr0.5)TiO3 film is larger than that of 320 for the (Ba0.75Sr0.25)TiO3 film. This indicated that dielectric constant is affected by the ratio of Ba/Sr composition. Leakage current density of less than 1×10-7 A/cm2 at 1 V and SiO2 equivalent thickness of 0.38 nm are measured at 120° C for 660° C-deposited (Ba0.5Sr0.5)TiO3 film of 30 nm in thickness. The (Ba0.5Sr0.5)TiO3 film has the possibility for application to generations beyond 256 Mbit dynamic random access memories.

Step Coverage and Electrical Properties of (Ba, Sr)TiO3 Films Prepared by Liquid Source Chemical Vapor Deposition Using TiO(DPM)2

Abstract: Thin films of (Ba, Sr)TiO3 (BST) with high dielectric constant were prepared on Pt/ SiO2/Si substrates of 6-inch-diameter by liquid source chemical vapor deposition using Ba(DPM)2, Sr(DPM)2 and TiO(DPM)2 (DPM=dipivaloylmethanato; C11H19O2) dissolved in tetrahydrofuran (THF). The reproducibility of ±3 % for the film composition was achieved by optimizing the deposition procedures. It was found that the coverage of 72%, obtained at the substrate temperature T s=753 K, was better than those obtained using other Ti sources such as Ti(O-i-Pr)4 (TTIP) and Ti(O-i-Pr)2(DPM)2. The electrical properties of the 480-A-thick BST film, deposited at T s=753 K using TiO(DPM)2, were as follows: dielectric constant e=230, equivalent SiO2 thickness t eq=7.8 A, leakage current density J L=6.7×10-6 A/cm2 at 1.65 V and dielectric loss tan δ=0.013.

Audio interactive tutor

Abstract: An all-audio, hands-free and eyes-free interactive tutor provides time-efficient and reduced-boredom instruction by varying a course of instruction based on the correct and incorrect responses of the user so as to frequently repeat and provide positive feedback for poorly-learned items of knowledge, to periodically refresh well-learned items and to suggest that rest be taken or to switch to easier material whenever too many human errors have occurred. The audio interactive tutor includes an audio input module, in the preferred embodiment a voice recognition unit based on a finite state grammar, an audio output module, a course of study and a user model. In a preferred embodiment, the course of study provides for human error control as well as for voice recognition unit error control, which synergistically cooperate to render the tutor substantially fault-tolerant and therewith enables the employment of commercially-available but not excessively accurate voice recognition units. The tutor may be embodied to operate on a PC or workstation, or may be embodied to operate as a stand-alone tutor. Spanish language instruction is disclosed in an exemplary embodiment.

System for unencumbered measurement and reporting of body posture

Abstract: A system for unencumbered measurement of body posture or attitude utilizeson-encumbering force or proximity sensors to monitor an individual, where the individual need not be aware of the presence or action of the sensors. Outputs from these sensors are analyzed to infer body posture or attitude. In one embodiment, a set of sensors is attached to a chair, or other surroundings such as the floor, at locations where a person may be in contact with or in close proximity to one or more of the sensors or where movement of the chair could be detected. Each sensor has an output which provides a signal indicative of a response of the sensor to forces exerted by or motions of the individual. The outputs of the sensors are processed to estimate the body posture of the individual.

Artificial retinas : fast, versatile image processors

Abstract: Artificial retinas combine video camera and image processing functions, allowing machines to function in their environment with unprecedented autonomy, or to augment quality control, surveillance and hazard monitoring. We review several retina devices and reveal how they execute basic manipulations of the image at processing speeds well beyond the capabilities of the human eye.

Measurement of kinematic and nuclear dependence of R = sigma-L / sigma-t in deep inelastic electron scattering

Abstract: We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement.

Scaleable very long instruction word processor with parallelism matching

Abstract: A system is provided to increase the efficiency of a VLIW, Very Long Insttion Word, processor which matches its level of parallelism, LOP, to the LOP of the executable code before executing the code's fixed-length VLIW instructions, so that object-level code compatibility is kept for different processor implementations of the same VLIW architecture required for different applications. Matching is accomplished either by reducing the LOP of the processor via inactivating the processor's functional units, or by effectively reducing the LOP of the executable code via the processor executing the sequential portions of each VLIW instruction in the code, with the length of the portions equal to or less than the number of operations that the processor can handle as a VLIW instruction.

Grammar checker interface

Abstract: A convenient interface for a grammar checking system in which improper utilization of words in a sentence is detected and in which corrected words are suggested for insertion in the sentence including means for underlining incorrectly used words and means for providing a caret or inverted V type indicia for words which are to be inserted, with the caret indicating a missing word in the sentence.

Hardware-software debugger using simulation speed enhancing techniques including skipping unnecessary bus cycles, avoiding instruction fetch simulation, eliminating the need for explicit clock pulse generation and caching results of instruction decoding

Abstract: The speed of a hardware-software debugger is markedly increased through the use of high speed simulators which ignore all systems operations except those where design errors are expected to manifest themselves, by skipping CPU bus cycles of no interest for the simulation, by not explicitly simulating periodic clock signals and generating only schedules of clock signals, and by caching instructions when alien computers are used in the simulation process to eliminate decoding of the instructions of the target computer.

Missile guidance algorithm against high-g barrel roll maneuvers

Abstract: The features of high-# barrel rolls for an aircraft and the countermeasures for a proportional navigation guidance missile against this maneuver are studied First, the features of the barrell roll maneuver, and the effects of the parameters on the miss distance are discussed The simulation results show that a high-£ barrel roll maneuver generally produces a larger miss distance than a split-S (a sustained maximum g turn) and the miss distance does not critically depend on the maneuver initiation time, if the aircraft has a certain length of "time-to-go" and maneuvers with an appropriate roll rate Second, the inference is made that the provision of a phase lead in the pitch-yaw plane in the missile guidance loop and adoption of the augmented proportional navigation guidance may be effective It is also proven that a large phase shift (but less than ir/2) results in a smaller miss distance and that the combination of the phase lead and the augmented proportional navigation produces better results

Halftone phase shift photomask, halftone phase shift photomask blank, and methods of producing the same

Abstract: A halftone phase shift photomask designed so that it is possible to shorten the photoengraving process, use a production line for a conventional photomask, prevent lowering of the contract between the transparent and semitransparent regions at a long wavelength in the visible region, which is used for inspection and measurement, and also prevent charge-up during electron beam exposure, and that ordinary physical cleaning process can be used for the halftone phase shift photomask. The halftone phase shift photomask has on a transparent substrate (1) a region which is semitransparent to exposure light and a region which is transparent to the exposure light so that the phase difference between light passing through the transparent region and light passing through the semitransparent region is substantially π radians. A semitransparent film that constitutes the semitransparent region is arranged in the form of a multilayer film including layers (3, 4) of chromium or a chromium compound. For example, the layer (3) is formed of chromium oxide, chromium oxide nitride, chromium oxide carbide, or chromium oxide nitride carbide, and the layer (4) is formed of chromium or chromium nitride. The layer (3) mainly serves as a phase shift layer, while the layer (4) mainly serves as a transmittance control layer that suppresses the rise of transmittance at the long wavelength side. The semitransparent film is formed by physical vapor deposition.

Apparatus and method for measuring thickness of thin semiconductor multi-layer film

Abstract: An interference waveform dispersion spectrum of light reflected from a multi-layer film is compared to a waveform obtained by numerical calculation using an optical characteristic matrix. Respective layer thickness values obtained from the calculated analysis of the Spatial interference waveform are subjected to waveform fitting with actually measured values. The theoretical interference spectrum is recalculated while changing approximate values of the layer thicknesses until a match is obtained to obtain precise respective layer thicknesses. The thicknesses of respective layers of a thin multi-layer film of submicron thicknesses can be non-destructively measured exactly and stably without direct contact.

Effect Plasma Transport on Etched Profiles with Surface Topography in Diverging Field Electron Cyclotron Resonance Plasma.

Abstract: Recent studies of electron cyclotron resonance (ECR) plasma etching for fabricating fine patterns of less than a half-micron indicate a serious problem in the etched profiles caused by a charge build-up of the patterns. The relationships between the local pattern distortion and the plasma properties measured by the electrostatic probe are investigated. Lowering the electron temperature perpendicular to the surface normal is one of the most effective techniques for eliminating the local side etch. It is enhanced by setting the wafer at the lower magnetic field. As the large space charge bends the ion trajectories, the higher ion current density also enhances the local side etch. The distribution of plasma potential which accelerates the ions can reduce the local side etch in spite of the higher current density.

A 10 bit 20 MS/s 3 V supply CMOS A/D converter

Abstract: A 10 bit CMOS A/D converter with 3 V power supply has been developed for being integrated into system VLSI's. In this A/D converter, redundant binary encoders named "twin encoders" enhance tolerance to substrate noise, together with employing differential amplifiers in comparators. The bias circuit using a replica of the amplifier is developed for biasing differential comparators with 3 V power supply. Subranging architecture along with a multilevel tree decoding structure improves dynamic performance of the ADC at 3 V power supply. The A/D converter is fabricated in double-polysilicon, double-metal, 0.8 /spl mu/m CMOS technology. The experimental results show that the ADC operates at 20 MS/s and the twin encoders suppress the influence of substrate noise effectively. This ADC has a single power supply of 3 V, and dissipates 135 mW at 20 MS/s operation. >

Preparation of (Ba, Sr)TiO3 Thin Films by Chemical Vapor Deposition Using Liquid Sources

Abstract: Thin films of (Ba, Sr)TiO3 with high dielectric constant were prepared on Pt/SiO2/Si substrates of 6-inch-diameter by chemical vapor deposition using liquid sources. Ba(DPM)2 and Sr(DPM)2 dissolved into tetrahydrofuran were vaporized in a vaporizer at 523 K, and Ti(O-i-C3H7)4 was bubbled at 313 K. The mixture of the source vapors with O2 and N2O was supplied to the reactor (10 Torr) at uniform velocities through a shower-type nozzle, which realized uniform profiles in the deposited film thickness and composition. The electrical properties are significantly influenced by the film composition, and the typical properties obtained for a 800-A-thick film prepared at the substrate temperature of 823 K are an equivalent SiO2 thickness t eq of 5.2 A, a leakage current J L of 2.4× 10-6 A/cm2 (at 1.65 V), and a dielectric loss tan δ of 0.07.

Apparatus for determining the structure of a hypermedia document using graph partitioning

Abstract: Apparatus for determining the structure of a hypermedia document containingext and graphics that are to be laid out on several linked pages includes a system that specifies the assignment of text and graphics to pages and the links between the pages via a reduction to graph partitioning and the use of optimization techniques for graph partitioning. In one embodiment, display items and relations between these display items are listed along with a measure of their importance. These factors are captured in terms of numeric weights for edges between nodes in the associated graph to permit the system to assign display items to pages, and determine which pages should be linked, so that a user can move between pages in the most efficient manner. In a further embodiment, to accommodate limited display area that restricts the number of display items and page links that can be displayed simultaneously, the system can take into account multistage page moves that allow the user to access display items on different pages in sequence by moving from one page to another via links on other pages, through the use of "stepping-stone" nodes in the associated graph that record possible traversal routes in the document that are not represented in other formulations of the hypermedia-document-layout task.

Spectroscopic Characterization of Low-Temperature Grown GaAs Epitaxial Films

Abstract: Femtosecond time-resolved reflectance and Raman scattering studies have been made on GaAs epitaxial layers grown at temperatures between 200 and 300° C and subsequently annealed. A subpicosecond carrier lifetime (∼0.25 ps) has been measured for a sample grown at 250° C and annealed at 600° C. Raman measurements using a back scattering geometry show a strong TO phonon band for samples grown at 200° C and 250° C, while it is absent for samples grown at 275 and 300° C. The band width of the LO band increases with decreasing growth temperature. A phonon band corresponding to As precipitates is also observed at 200 cm-1 for samples grown at 200 and 250° C. A strong correlation is found between the measured carrier lifetime and Raman profile.