In this paper we determine the performance of a direct sequence spread spectrum multiple access system where the users utilize different carrier frequencies. This scheme is applicable to a system, such as an indoor wireless communication system utilizing very high frequencies, where the available bandwidth is so large that it is not feasible to spread the signal over the whole band. The multi-user interference is modeled as a compound Gaussian random variable and expressions are found for the variance of the interference as a function of relative phase and frequency parameters. In addition to different carrier frequencies the analysis also accounts for offsets in the chip clock frequencies, general chip pulse shaping function, and different received signal powers. We give results for the error probability in a multiple access system utilizing BPSK, QPSK, and OQPSK modulation.

This paper presents a technique by which any linear CCD camera, be it one with lens distortions, or even one with misaligned lens and CCD, may be calibrated to obtain optimum performance characteristics. The camera-image formation model is described as a polynomial expression, which provides the line-of-sight flat-beam, including the target light-spot. The coefficients of the expression, which are referred to as camera parameters, can be estimated using the linear least-squares technique, in order to minimize the discrepancy between the reference points and the model-driven flat-beam. This technique requires, however, that a rough estimate of camera orientation, as well as a number of reference points, are provided. Experiments employing both computer simulations and actual CCD equipment certified that the model proposed can accurately describe the system, and that the parameter estimation is robust against noise.

The threshold characteristics of mutually coupled SQUIDs (Superconducting Quantum Interference Devices) have been analytically and numerically investigated. The mutually coupled SQUIDs investigated is composed of an rf-SQUID and a dc-SQUID. Here, the rf-SQUID is a flux quantum generator and the dc-SQUID is a flux detector. The linearization method substituting sin-1x by (π/2)x (1x1) is found valid when it is applied to the mutually coupled SQUIDs, because it is possible to obtain the superconducting regions analytically. By computer implementation of linearization method, we found this method is very effective and very quick compared to the ordinary methods. We report the internal flux on an rf-SQUID, the threshold of a dc-SQUID, and that of mutually coupled SQUIDs obtained by Lagrange multiplier formulation and linearization. The features of the threshold characteristics of the mutually coupled SQUIDs with various parameters are also reported. The discontinuous behavior of threshold of the mutually coupled SQUIDs are attractive for digital applications. We suggest three applications of the mutually coupled SQUIDs, that is, a logic gate for high-Tc superconductors (HTSs), a neuron device, and an A/D converter.

We applied an artificial neural network approach identify possible tumors into benign and malignant ones in mammograms. A sequential-dependence technique, which calculates the degree of redundancy or patterning in a sequence, was employed to extract image features from mammographic images. The extracted vectors were then used as input to the network. Our preliminary results show that the neural network can correctly classify benign and malignant tumors at an average rate of 85%. This accuracy rate indicates that the neural network approach with the proposed feature-extraction technique has potential utility in the computer-aided diagnosis of breast cancer.

In this letter, a practical functional test method is proposed for production tests of microprocessor based sequence controllers. In our method, a controller under test is determined as a faulty one if the outputs defined in the process flowchart can not be provided from the circuit.

In this letter, the effectiveness of the quasi-TEM approximation is studied for the microstrip line including optically induced semiconductor plasma region. This approximation is considered to be efficient under several restrictions such as the upper limit of the microwave frequency and the plasma density.

The test pattern generation for sequential circuits is more difficult than that for combinational circuits due to the presence of memory elements. Therefore we proposed a method for synthesizing sequential circuits with testability in the level of state transition table. The state transition table is augmented by adding extra two inputs so that it possesses a distinguishing sequence, a synchronizing sequence, and transfer sequences of short length. In this case the checking sequence which do a complete verification of the circuit can be test pattern. The checking sequence have been impractical due to the longer checking sequence required. However, in this paper, we have discussed the condition to reduce the length of checking sequence, then by using suitable state assignment codes sequential circuits with much shorter checking sequences can be realized. A heuristic algorithm of the state assignment which reduce the length of checking sequence is proposed and the algorithm and reduced checking sequence are presented with simple example. The state assignment is very simple with the state matrix which represents the state transition. Furthermore some experimental results of automated synthesis for the MCNC Logic Synthesis Workshop finite state machine benchmark set have shown that the state assignment procedure is efficient for reducing checking sequences.

A shift down of the resonance frequency is claimed to be used as a simple practical test for the onset of chaos based on a common feature of forced damped nonlinear oscillation systems which exhibit cascading bifurcations to chaos.

A method to analyze two-pattern test capabilities of autonomous test pattern generator (TPG) circuits for use in built-in self-testing are described. The TPG circuits considered here include arbitrary autonomous linear sequential circuits in which outputs are directly fed out from delay elements. Based on the transition matrix of a circuit, it is shown that the number of distinct transitions in a subspace of state variables can be obtained from rank of the submatrix. The two-pattern test capabilities of LFSRs, cellular automata, and their fast parallel implementation are investigated using the transition coverage as a metric. The relationships with dual circuits and reciprocal circuits are also mentioned.

This paper proposes new architecture LSIs based on wave-parallel computing to provide an essential solution to the interconnection problems in massively parallel processing. The basic concept is ferquency multiplexing of digital information, which enables us to utilize the parallelism of electrical (or optical) waves for parallel processing. This wave-parallel computing concept is capable of performing several independent binary funtions in parallel with a single module. In this paper, we discuss the design of wave-parallel image processing LSI to demonstrate the feasibility of reducing the number of interconnections among modules.

This system called COKIS automatically extracts knowledge about C functions from the UNIX on-line manual by using its description paragraph and the user can interactively inquire to the system in order to know about UNIX C functions. The idea is motivated on the one side to free users from being involved in an exhaustive knowledge acquisition in the past, and to examine problems in understanding knowledge itself on the other. We propose Memory Processor which is implemented to realize extracting knowledges from corpus and processing dialogues in the inquiry system at the same modules.

In order to describe the flow passing through the glottis, we constructed a dynamic three-dimensional finite element model of the human larynx. The transient flow fields in the laryngeal model were calculated to examine the dynamic effects generated by the vocal fold vibration. A phase difference between the upper and lower edges of the vocal folds was included in the model to investigate the effect of the glottal shapes on pressure-flow relationships in the larynx during the vocal fold vibration. Using STAR-CD thermofluids analysis system, which is capable of treating the transient flow in moving-boundary situations with finite volume method, we solved the viscous incompressible Navier-Stokes equations to investigate the glottal flows and transglottal pressures as a function of the vocal fold vibration. The results were compared to the uniform glottis model and the theoretical model proposed by Ishizaka and Matsudaira, respectively. The effects of dynamic factors on the pressure distributions and flow patterns in the larynx resulting from the vocal-fold vibration were also discussed.

A new transfer mode and a switching architecture which can support loss free and no delay jitter service class with shorter switching delay compared with "stop and go queueing scheme" is proposed. This scheme combines ATM scheme with hierarchical STM framing concept.

In our recent work, a forward test generation method for sequential circuits by using a single time frame was proposed. In order to improve the effectiveness of the method, we introduced an extended mode which can handle the two time frames for a hard-to-test fault and a state escaping phase which can detect a sequence of unsuitable states for test generation. The experimental results show that the improved method is effective in generating higher coverage tests with a small number of tests.

This paper deals with study results on the effect of nonlinear amplification in the CDMA system using offset-QPSK signals bandlimited with a square-root cosine roll-off filter. As a result of the study, it is shown that the nonlinear amplification does not affect bit error rate performance with reasonable out-of-band emission characteristics when the roll-off factor of the transmit filter is one.

A laser system which has a mirror outside of it to feedback a delayed output has been described by the Maxwell-Bloch equations with time delay. It is shown that a chaotic behavior in the equations can be controlled by using a OPF control algorithm. Our numerical simulation indicates that the chaotic behavior is stabilized on 1, 2 periodic unstable orbits.

Current status and critical issues of the material and device technology towards constructing new architecture LSIs based on quantum-mechanical principles are reviewed in an attempt to draw attention of systems workers to the field. Limitations of the present-day LSI architecture are discussed from the viewpoints of material science and device physics. New quantum mechanical phenomena in the quantum structures are reviewed. Then, key material and processing issues for fabrication of desired quantum structures are briefly discussed. Finally, the basic operation principles the quantum devices and possible architectures of quantum LSIs are discussed.

We discuss possible new principles of information processing by utilizing microscopic, semi-microscopic and macroscopic phenomena occuring in nature. We first discuss quantum mechanical universal information processing in microscopic world governed by quantum mechanics, and then we discuss superconducting phenomena in a mesoscopic system, especially an information processing system using flux quantum. Finally, we discuss macroscopic self-organizing phenomena in biology and suggest possibility of self-organizing devices.

This letter proposes an LSP quantizing method which uses interframe correlation of the parameters. The quantized parameters are represented as a moving average of code vectors. Using this method, LSP parameters are quantized efficiently and the degradation of decoded parameters caused by bit errors affects only a few following frames.

Scaling-down of MOSFETs (metal-oxide-semiconductor field effect transistors can be divided to semi-classical and quantum mechanical one. In the regime of semi-classical scaling-down the behavior of electrons and holes can be well described with the effective mass approximation and in the regime of quantum mechanical scaling-down the characteristics of electrons and holes as wave becomes markedly. The minimum size limit of MOSFETs scaled down in semi-classical regime is mainly determined by the subthreshold characteristics and the short channel effect on the threshold voltage and 0.1 µm will be the minimum channel length from practical viewpoints. Scaling down of MOSFETs enhances their operational speed, but the substrates with high resistivity which are often used in SOI (silicon on insulator) substrates result longer dielectric relaxation time. While the dielectric relaxation time becomes longer than the reciprocal of signal frequency, the semiconductors work as lossy dielectrics and may lead to new types of dynamic circuits. Modification of material properties utilizing the wave nature of electrons is an illustration of quantum mechanical way to improve characteristics of MOSFETs. Suppression of optical phonon scattering of two dimensional electrons by introducing two dimensional array of quantum dots into substrates is expected to improve high field characteristics of material. Brillouin zone folding is another way to control the band structure of materials, especially to make the indirect transition band structure to the direct transition band structure. Heat transfer from a chip severely limits the number of devices which can be integrated on the chip. Reduction of signal charge to electronic elementary charge, that is quantum limit, is expected to be useful for realization of nano-power electronics.