Showing papers by "Mitsubishi Electric published in 1993"

Rayleigh fading compensation for QAM in land mobile radio communications

Abstract: A pilot symbol-aided Rayleigh fading compensation is investigated for M-ary quadrature amplitude modulation (QAM) to achieve highly spectrally efficient land mobile communication systems. The optimum parameters for fading compensation, bit error rate (BER) performance against E/sub b//N/sub 0/ (energy per bit to the noise power spectrum density), adjacent channel interference, and cochannel interference for 16-QAM, 64-QAM, and 256-QAM, and the spectral efficiencies for these modulation schemes in Rayleigh fading environments are investigated by computer simulation. To further verify the effect of pilot symbol-aided fading compensation from a a practical point of view, a 16-QAM modem is implemented, laboratory experiments are executed, and the impact of the dynamic range limitation due to the resolution of the analog-to-digital (A/D) converters is evaluated, along with the imperfection of the analog circuits. It is demonstrated by computer simulation and laboratory experiments that the pilot symbol-aided fading compensation can sufficiently compensate for fast varying Rayleigh fading, and 16-QAM gives the highest spectral efficiency in the case of cellular systems. >

The Use of Robotics Technology to Study Human Joint Kinematics: A New Methodology

Abstract: Robotics technologies have been modified to control and measure both the force and position of synovial joints for the study of joint kinematics. One such system was developed to perform kinematic testing of a human joint. A 6-axis articulated robotic manipulator with 6 degrees of freedom (DOF) of motion was designed and constructed; a mathematical description for joint force and position was devised; and hardware and software to control forces applied to the joint, as well as position of the joint, were developed. The new methodology was utilized to simulate physiological loading conditions and to perform an anterior-posterior (A-P) translation test on a human cadaveric knee. Testing showed that this new system can simulate complex loading conditions and also measure the resulting joint kinematics.

Static power conditioner using GTO converters for AC electric railway

Abstract: This paper proposes a static power conditioner (SPC) using self-commutated inverters in order to solve the problems of an AC electric railway. For compensating the voltage unbalance of a three-phase electric power system, the SPC controls the electric power in railway substations. Besides, for compensating the voltage drop in the feeding circuit, the SPC controls the reactive power in sectioning post. Further, it can also control the harmonic currents, so the SPC can be expected to be an ideal compensator. This paper gives an outline of the SPC, the theoretical studies of compensation using an SPC and the results of simulation of its performance. >

A balanced hierarchical data structure for multidimensional data with highly efficient dynamic characteristics

Abstract: A new multidimensional data structure, multidimensional tree (MD-tree), is proposed. The MD-tree is developed by extending the concept of the B-tree to the multidimensional data, so that the MD-tree is a height balanced tree similar to the B-tree. The theoretical worst-case storage utilization is guaranteed to hold more than 66.7% (2/3) of full capacity. The structure of the MD-tree and the algorithms to perform the insertion, deletion, and spatial searching are described. By the series of simulation tests, the performances of the MD-tree and conventional methods are compared. The results indicate that storage utilization is more than 80% in practice, and that retrieval performance and dynamic characteristics are superior to conventional methods. >

A half-pel precision motion estimation processor for NTSC-resolution video

Abstract: A motion estimation processor compatible with CCITT H.261 and MPEG (Moving Pictures Experts Group) standards is described. A half-pel precision processing unit with an exhaustive block matching unit for integer-pel precision search is introduced. The necessary processing power for the exhaustive block matching is implemented with a one-dimensional array structure using a subsampling technique. The problem of communication bandwidth to the frame memory, which is a bottleneck of half-pel precision motion estimation, is solved by introducing a candidate pixel buffer in the interprocessor data transfer. It is noted that this is the first single-chip solution proposed that is capable of processing NTSC-resolution video in real time in 40-MHz operation.

A study on the short circuit destruction of IGBTs

Abstract: The short-circuit destruction of class n-ch 600-V IGBTs (insulated-gate bipolar transistors) is investigated experimentally and analyzed with the help of device simulation, focusing on three major destruction modes (power constant, energy constant, and turn-off destruction). Measured power dissipation for power constant destruction is 2000 approximately 2400 kW/cm/sup 2/, which coincides with the simulation result. The energy constant destruction and turn-off destruction are found to depend on the thermal effect. The critical temperature for destruction is predicted to be 350 degrees C. >

Some aspects of a realistic three-dimensional pursuit-evasion game

Abstract: A three-dimensio nal pursuit-evasion game between a realistic missile and an aircraft is studied employing point-mass models for both vehicles. Since a direct method to solve this complicated mini-max problem is too time-consuming, the study is conducted by carrying out massive simulations in the parameter space of initial conditions and guidance law parameters. The important role of information in the opponent's acceleration to the game and the effectiveness of the strategy in rotating the line-of-sight vector are shown. It is found that there exist very few cases where the aircraft can avoid the missile, among them typical air-combat maneuvers such as linear acceleration, high-£ barrel roll, split-S, and horizontal-S. Nomenclature flcmax = missile lateral acceleration command limit Ompjdmy = missile acceleration components measured in aircraft pitch and yaw axis, respectively ^p^y^pc^yc = missile-pitch and yaw-axis lateral accelerations and their command signals OpttOyt = aircraft-desir ed pitch and yaw acceleration components, respectively Otp9oty = aircraft acceleration components measured in missile pitch and yaw axis, respectively CD = drag coefficient CDO

A 622-Mb/s 8*8 ATM switch chip set with shared multibuffer architecture

Abstract: An asynchronous transfer mode (ATM) switch chip set, which employs a shared multibuffer architecture, and its control method are described. This switch architecture features multiple-buffer memories located between two crosspoint switches. By controlling the input-side crosspoint switch so as to equalize the number of stored ATM cells in each buffer memory, these buffer memories can be treated as a single large shared buffer memory. Thus, buffers are used efficiently and the cell loss ratio is reduced to a minimum. Furthermore, no multiplexing or demultiplexing is required to store and restore the ATM cells by virtue of parallel access to the buffer memories via the crosspoint switches. Access time for the buffer memory is thus greatly reduced. This feature enables high-speed switch operation. A three-VLSI chip set using 0.8- mu m BiCMOS process technology has been developed. Four aligner LSIs, nine bit-sliced buffer-switch LSIs, and one control LSI are combined to create a 622-Mb/s 8*8 ATM switching system that operates at 78 MHz. In the switch fabric, 155-Mb/s ATM cells can also be switched on the 622-Mb/s port using time-division multiplexing. >

A motor-driven control valve device

Abstract: A pushing type motor-driven control valve device for opening and closing a valve (5) by a reciprocating motion of a motor shaft driven by normally and reversely rotating a motor, said pushing type motor-driven control valve device comprises a valve shaft (7) for driving the valve (5); a motor shaft (33) for driving the valve shaft (7), said motor shaft being separated from and disposed coaxially with the valve shaft; a valve shaft spring (12) for urging the valve shaft (7) in a first direction of closing the valve; and a motor shaft spring (40) for urging the motor shaft (33) in a second direction of opening the valve; wherein a first pushing force applied on the motor shaft by the motor shaft spring is set to be smaller than a second pushing force applied on the valve shaft by the valve shaft spring.

Direct cache coupled network interface for low latency

Abstract: A low latency network receive interface reduces the copying of message data by directly coupling the network to a cache and by providing an address-based message in which an incoming message block preincorporates an address so that messages can be directly stored in their final destination. In a preferred embodiment, the message data size is made equal to the cache block size so that cache blocks can be updated atomically. The small message size--which is equivalent in size to a cache block--also reduces transfer time, unlike Direct Memory Access (DMA) approaches in which a large amount of data must accumulate prior to transfer to main memory as a block. In one embodiment, the cache to which message data is directly coupled is divided into a message cache and a data cache, with the incoming message block coupled directly to the message cache. When an incoming message arrives, its address is compared with addresses in the data cache, with the data in the data cache at this address being purged in an invalidation process if the particular address is priorly occupied. The processor first accesses the data cache, and if no valid data exists at the corresponding address, it accesses the memory cache, which is in turn followed by accessing main memory if no valid cache data exists. This direct cache coupling of incoming message data eliminates latency due to buffering of the incoming message data in temporary storage prior to copying the message data.

Comparison of image coding techniques with a picture quality scale

Abstract: A newly developed Picture Quality Scale (PQS) provides a numerical measure of image quality for monochrome images well correlated with the Mean Opinion Score. In this paper, we report some results on the evaluation and comparison of image coding methods with such an objective quality measure. The emphasis is given here to the evaluation of the quality of JPEG coding standard. We also review and discuss the important new areas of research that an objective distortion measure now makes possible.

Leak detection in a reduced pressure processing apparatus

Abstract: A reduced pressure processing apparatus includes a processing vessel for performing predetermined processing to an object to be processed in a reduced pressure atmosphere, an exhaust mechanism, including a main exhaust system having a relatively high exhaust pressure and a sub-exhaust system having a relatively low exhaust pressure, for evacuating the processing vessel, and an oxygen gas concentration sensor for detecting an oxygen gas concentration in the processing vessel during exhaust performed by the sub-exhaust system. The oxygen gas concentration in the processing vessel is detected while the processing vessel is evacuated with a relatively low exhaust pressure. It is determined whether leakage is present or absent by confirming a detection value is a predetermined value or less within a predetermined period of time. When leakage is absent, the processing vessel is evacuated with the relatively high exhaust pressure. When leakage is present, the exhaust is interrupted, and necessary processing is performed. When the processing vessel is set in a desired reduced pressure state, predetermined processing is performed to the substrate.

Arm path planning for a space robot

Abstract: A path planning method for the manipulator arm of a space robot is presented. The purpose of the path planning is to control the manipulated satellite attitude as well as the joint angles of the arm. The joint angles are expressed by two parameters, and a relation between the attitude change and the motion of the parameters is derived., Based on the relation, an algorithm for determining a joint angle path to cause the desired attitude change is proposed. A numerical study is executed using a space robot model with a manipulator arm having six degrees of freedom. The result shows that the algorithm is effective for obtaining the joint angle path of the space robot.

Self-replicating sequences of binary numbers☆

Abstract: An algorithm is proposed which allows sequences of binary numbers to interact. We introduce a two-dimensional matrix form of the sequences achieved by a general folding method. Interactions between one- and two-dimensional forms of binary sequences generate new sequences, which compete with the original ones due to selection pressure. Starting from random initial populations, replicating and self-replicating sequences are generated in large numbers. We report on results for four-digit sequences and propose nonlinear differential equations modelling the system.

A 1.9-GHz-band GaAs direct-quadrature modulator IC with a phase shifter

Abstract: A 1.9-GHz-band direct-quadrature modulator IC has been successfully developed for digital portable telephone use. In the 1.9-GHz high-frequency band, both image and carrier rejections as low as -40 dBc have been obtained with a low-power dissipation of 110 mW at a single power supply of 3.1 V, corresponding to a phase error below 1.1. In order to reduce undesired sideband spectral components required for digital modulation, a newly developed circuit configuration that combines a quadrature phase shifter with drivers for amplitude imbalance compensation and makes spectrum efficiency and low-power dissipation possible is used. The modulator IC may be used in enhanced digital mobile radiocommunication systems such as digital portable telephones. >

Optical learning neurochip with internal analog memory.

Abstract: An optical neurochip with learning capability and a memory function is reported for the first time, to our knowledge. The neurochip is a three-dimensional optoelectronic integrated circuit consisting of a light-emitting diode array and a variable-sensitivity photodetector array. The principle of operation and the fundamental characteristics of the neurochip are described in detail. The synaptic weights, which, are acquired through learning, are stored in the variable-sensitivity photodetector as the detection sensitivity with analog values. Both the positive and the negative synaptic weights are memorized with one variable-sensitivity photodetector element by changing the polarity of the electric signal applied to the photodetector. A storage time of ~20 min. was obtained. With a fabricated optical neurochip that had 32 neurons and 32 × 32 synapses, experiments of on-chip learning for pattern classification were performed successfully.

A high speed 0.6- mu m 16 K CMOS gate array on a thin SIMOX film

Abstract: 0.6- mu m CMOS technologies were developed on thin SIMOX film and applied to a 16 K gate CMOS gate array. High-speed operation with low power consumption characteristics was verified with ring oscillators on the thin SOI CMOS gate array with V/sub D/=3 V, compared with bulk-Si ring oscillators with the same dimension. Parasitic capacitances in thin SOI and bulk-Si circuits were estimated to clarify the origin of the speed gain from the propagation delay times of the ring oscillators with various kinds of controlled load capacitances. Full functional operation was achieved for a 16 b*16 b multiplier on the SOI CMOS gate array with 1.4 times higher speed operation and 0.8 times lower power consumption than the multiplier on a bulk-Si substrate. >

Insulated gate semiconductor device

Abstract: In order to prevent a malfunction caused by an electrical noise and limit an excessive main current at a high speed while cutting off the same to a value close to zero, the main current is regulated by an IGBT (1) which is connected with a load. A part of this main current is shunted to another IGBT (2). The as-shunted current flows through a resistor (3), to be converted to a voltage across the resistor (3). When the main current is excessively increased by shorting of the load or the like, this voltage exceeds a prescribed value so that a transistor (5) and a thyristor (7) enter conducting states. Consequently, a voltage across a gate (G) and an emitter (E) of the IGBT (1) is so reduced as to cut off the main current. The transistor (5) prevents the main current from excessive increase since the same has a high speed of response, while the thyristor (7) cuts off the main current to zero since the same has lower resistance in conduction.

Future technological and economic prospects for VLSI

Abstract: Technological trends for VLSI are discussed, with emphasis on process/device technology and function/performance forecasts. Economic trends are then examined. The production cost and design cost of VLSI are analyzed. Particular attention is given to the production cost of VLSI, for example, DRAMs (dynamic random access memory) and gate arrays, which have driven the progress in silicon-based-memory process technology and in ASIC (application-specific integrated circuit) design technology, respectively. Future production-cost trends are estimated for both. >

Structure of 600 V IC and a new voltage sensing device

Abstract: A novel high-voltage isolation structure which has a 600-V breakdown voltage has been developed. This structure realizes improved stability of the breakdown voltage by combining reduced surface field (RESURF) technology with a multiple floating field plate (MFFP) and an n/sup +//n/sup -/ buried layer. A high-voltage n-ch MOSFET was realized by combining a lateral DMOS structure with the high-voltage isolation structure. A high-voltage p-ch MOSFET was realized by combining the offset gate using the polysilicon layer of the MFFP. A novel voltage sensing device was constructed by the addition of a p-type floating layer to the high-voltage isolation structure. Its output voltage is automatically restricted within the logic power supply level. >

Information theoretic analysis of action potential trains

Abstract: A crosscorrelational method of action potential trains has been proposed, based on information theory Two information theoretic quantities, mutual information and channel capacity, were calculated from a pair of action potential trains for detecting a crosscorrelation and estimating synaptic connectivity The method was compared with conventional ones, using action potential trains obtained by the simulation of a neuron model This method was shown to have the advantages to more easily find a weak but significant crosscorrelation and to give better estimation of synaptic connectivity independent of the firing probability of a presynaptic neuron

Influence of Hydrogen on Electrical Characteristics of Poly-Si Resistor

Abstract: This paper shows that different amounts of hydrogen are absorbed into polycrystalline silicon (Poly-Si) film depending on its Structures such as oxide film under Poly-Si film and metallization pattern on Poly-Si film. We examined how hydrogen affected the conductive mechanism of Poly-Si film, and measured the absorption of hydrogen into Poly-Si film by elastic recoil detection analysis (ERDA). Our investigations revealed that the change in Poly-Si film resistance was caused by a decrease in trap density, which occurred when dangling bonds were filled with hydrogen. This hydrogen was due to diffusion of hydrogen in plasma-enhanced chemical-vapor-deposited silicon nitride (P-SiN) film. It was confirmed that the absorption of hydrogen was the cause of the decrease in resistance using ERDA.

Semiconductor device, resin for sealing same and method of fabricating same

Abstract: There is disclosed a semiconductor device wherein electrode terminals (2), elements (6) and wires (7) are disposed on a base plate (5) of a case (4) filled with only epoxy resin (1). The epoxy resin (1) contains impurities such as halogen and alkaline metallic salts in an amount of not more than 5 ppm and has a linear expansion coefficient of 5 × 10⁻⁶ to 25 × 10⁻⁶ when hardened. The semiconductor device provides for direct sealing of the components, whereby its size and cost are reduced.

Self-replicating sequences of binary numbers. Foundations I: General

Abstract: We propose the general framework of a new algorithm, derived from the interactions of chains of RNA, which is capable of self-organization. It considers sequences of binary numbers (strings) and their interaction with each other. Analogous to RNA systems, a folding of sequences is introduced to generate alternative two-dimensional forms of the binary sequences. The two-dimensional forms of strings can naturally interact with one-dimensional forms and generate new sequences. These new sequences compete with the original strings due to selection pressure. Populations of initially random strings develop in a stochastic reaction system, following the reaction channels between string types. In particular, replicating and self-replicating string types can be observed in such systems.

Oxidation/diffusion processing apparatus

Abstract: An oxidation/diffusion processing apparatus includes a processing vessel, arranged such that a longitudinal direction is vertical, for storing a plurality of target objects to be processed, a heater arranged around the processing vessel, for heating the interior of the processing vessel, a process gas supply mechanism for supplying a process gas from the lower portion of the processing vessel into the processing vessel, and an exhaust mechanism for exhausting a processed exhaust gas from the upper portion of the processing vessel. The process gas is supplied to the target objects heated to a predetermined temperature by the heater to perform oxidation/diffusion processing to the target objects.