In this paper, the improvement technique for a nonlinear parallel interference cancellation (PIC) receiver for a DS-CDMA system is studied, which cancels only the estimated multiple access interference (MAI) from specific users at each receiver stage. This technique was introduced as a PIC receiver using null zone hard decision in the proceeding of IEEE MILCOM '94, but the numerical results has not been fully provided with varying decision threshold. In this paper, the performance of the PIC receiver using null zone hard decision is shown in a Rayleigh fading channel. Also, a new PIC receiver with an adaptive decision threshold is proposed. In the proposed new PIC receiver, the decision threshold for partial cancellation is adjusted according to the statistic of its matched filter (MF) outputs. The BER of the proposed PIC receiver is obtained by simulation and compared with those of the conventional PIC receiver and the PIC receiver using null zone hard decision in a Rayleigh fading channel. It is shown that the proposed PIC receiver achieves better performance than the conventional PIC receiver and the PIC receiver using null zone hard decision in a Rayleigh fading channel.

A constraint resolution scheme in the Hopfield-type neural network named "Neuron Filter" is presented for efficiently solving combinatorial optimization problems. The neuron filter produces an output that satisfies the constraints of the problem as best as possible according to both neuron inputs and outputs. This paper defines the neuron filter and shows its introduction into existing neural networks for N-queens problems and FPGA board-level routing problems. The performance is evaluated through simulations where the results show that our neuron filter improves the searching capability of the neural network with the shorter computation time.

This paper describes the formula for dynamic power dissipation of a track/hold circuit as a function of the input frequency, the input amplitude, the sampling frequency, the track/hold duty cycle, the power supply voltage and the hold capacitance for a sinusoidal input.

In this paper, we propose an effective SOI yield engineering methodology by practical usage of 2D simulations. Process design for systematic yield of Fully-Depleted SOI MOSFET requires specific consideration of floating-body effects and parasitic channel leakage currents. The influence of varied SOI layer thickness to such phenomena is also complicated and substantial. Instead of time-consuming 3D simulators, 2D simulators are used to optimize the process considering these effects in acceptable turn around time. Our methodology is more effective in future scaled-down process with decreased SOI layer thickness.

We have developed a map-based approach that enables us to efficiently extract information about man-made objects, such as buildings, from aerial images. An image is matched with a corresponding map in order to estimate the object information in the image (i. e. , presence, location, shape, size, kind, and surroundings). This approach is characterized by using a figure contained in a map as an object model for a top-down (model-driven) analysis of an object in the aerial image. We determined the principal steps of the map-based approach needed to extract object information and update a map. These steps were then applied to obtain the locations of missing buildings and the heights of existing buildings. The extraction results of experiments using aerial images of Kobe City (taken after the 1995 earthquake) show that the approach is effective for automatically extracting building information from aerial images and for rapidly updating map data.

Carrier mobilities in poly(3-alkylthiphene) cast films have been studied by means of fabricating a field effect transistor (FET) at the field range of (0.4-1.6)104 V/cm. It is found that the regioregurality is markedly effective to the mobilities than the side chain length. The FET mobilility of the regioregular poly(3-hexylthiophene), PHT is approximately 310-3 cm2/Vs which is larger than that of regiorandom PHT by 3 orders of magnitude. The mobility of regioregular poly(3-dodecylthiophene), PDDT is 810-4 cm2/Vs and is also 3 orders of magnitude larger than that of regiorandom PDDT. The mobilities of regioregular ones decrease, however, those of regiorandom ones increase at higher fields. The FET mobilities are nearly same to the mobilities estimated by the time of flight method. These results have been discussed taking the regularity of the main chain and the length of side chain into consideration.

Photocarrier transport of regiorandom poly(3-hexylthiophene) P3HT in ITO/P3HT/Al sandwich cell configuration has been investigated by means of Time-of-Flight technique. Characteristics of Schottky diode and the magnitude of hole mobility have been found to be affected by impurities involved during the synthesis. The hole mobility in regiorandom P3HT at room temperature has been estimated to be 2.4 10-5 and 2.6 10-4 cm2/V. s before and after the removal of ferric ions, respectively, at a field of 5.0105 V/cm. Field dependencies of mobility before and after purification show unique feature and have been discussed in terms of the disorder model.

For plasma simulations, we developed a one-dimensional (1d) Object-Oriented Particle-in-Cell code for X11-based Unix workstations (XOOPIC) by modifying the current two-dimensional version which was originally developed by PTSG (Plasma theory and simulation group) in the University of California at Berkeley. We implemented a simplified field solve and current deposition in the code. We retained three components of particle velocity, although the spatial variation for particle position and field components is limited to one dimension. To verify the function of the 1d code, we perform simulations with typical models such as the Child-Langmuir current model and electromagnetic wave propagation in plasma. In both cases, the simulation results quantitatively agree with the theory.

In this paper, we propose an idea of the generalization of threshold signature and authenticated encryption for group communications. The concept of the (t, n) threshold signature with (k, l) shared verification is implemented in group-oriented cryptosystems. In the system, any t members can represent a group to sign a message and any k verifiers can represent another group to authenticate the signature. By integrating the cryptographic techniques of data encryption, digital signature and message recovery, a group-oriented authenticated encryption scheme with (k, l) shared verification is also proposed. The message expansion and communication cost can also be reduced in our schemes.

The conventional back-propagation algorithm cannot be applied to networks of units having hard-limiting output functions, because these functions cannot be differentiated. In this paper, a gradient descent algorithm suitable for training multilayer feedforward networks of units having hard-limiting output functions, is presented. In order to get a differentiable output function for a hard-limiting unit, we utilized that if the bias of a unit in such a network is a random variable with smooth distribution function, the probability of the unit's output being in a particular state is a continuously differentiable function of the unit's inputs. Three simulation results are given, which show that the performance of this algorithm is similar to that of the conventional back-propagation.

A theoretical study on high slope-efficiency phase-shifted DFB laser diodes is presented. We have proposed a new grating structure called asymmetrically-pitch-modulated (APM) grating, and calculated its slope- efficiency and single-mode-yield. In order to take into account the modulated grating period; we have developed an F-matrix which directly includes a chirped grating structure. APM phase-shifted DFB laser diodes consist of a uniform grating in one half section of the cavity and a chirped grating in the other half. This structure causes asymmetrical field distribution inside the cavity and the optical output power from one facet is larger than that from the other facet. According to the simulation results, when the normalized coupling coefficient κ L is 3.0, the front-to-rear output power ratio is 2.6, while the single-mode-yield remains at 100%, and simultaneously the slope-efficiency improvement becomes 65% better than that of ordinary quarter-wave phase-shifted DFB lasers of the same κ L value.

Taking traveling salesman problems (TSPs) as examples of combinatorial optimization problems, an "optimal" Hopfield network for ("optimal" neural representation of) TSPs is presented, where a vertex of state hypercube of the network is asymptotically stable if and only if it is an optimal solution. Of all the Hopfield networks for TSPs, this network most sharply distinguishes an optimal solution from other nonoptimal solutions and infeasible solutions. In this sense, we call this network "optimal" for TSPs. Whenever the network converges to a vertex, we can always obtain an optimal solution. However, we can not design such network without knowing an optimal solution to the problem. So, its approximate realization, which can be designed without a-priori knowledge of an optimal solution, is proposed. Simulations show that the "optimal" network and its approximate realization obtain optimal or good feasible solutions more frequently than familiar Hopfield networks. We can also design such "optimal" Hopfield networks for many combinatorial optimization problems as well as for TSPs.

The homogeneous structure of field programmable gate arrays (FPGAs) suggests that the defect tolerance can be achieved by shifting the configuration data inside the FPGA. This paper proposes a new approach for tolerating the defects in FPGA's configurable logic blocks (CLBs). The defects affecting the FPGA's interconnection resources can also be tolerated with a high probability. This method is suited for the makers, since the yield of the chip is considerably improved, specially for large sizes. On the other hand, defect-free chips can be used as either maximum size, ordinary array chips or fault tolerant chips. In the fault tolerant chips, the users will be able to achieve directly the fault tolerance by only shifting the design data automatically, without changing the physical design of the running application, without loading other configurations data from the off-chip FPGA, and without the intervention of the company. For tolerating defective resources, the use of spare CLBs is required. In this paper, two possibilities for distributing the spare resources (king-shifting and Horse-allocation) are introduced and compared.

This paper presents a new design for testing SRAM-based field programmable gate arrays (FPGAs). The original FPGA's SRAM memory is modified so that the FPGA may have the facility to loop the testing configuration data inside the chip. The full testing of the FPGA is achieved by loading typically only one carefully chosen testing configuration data instead of the whole configurations data. The other required configurations data are obtained by shifting the first one inside the chip. As a result, the test becomes faster. This method does not need a large off-chip memory for the test. The evaluation results prove that this method is very effective when the complexity of the configurable blocks (CLBs) or the chip size increases.

A new elliptic curve scalar multiplication algorithm is proposed. The algorithm offers about twice the throughput of some conventional OEF-base algorithms because it combines the Frobenius map with the table reference method based on base-φ expansion. Furthermore, since this algorithm suits conventional computational units such as 16, 32 and 64 bits, its base field Fpm is expected to enhance elliptic curve operation efficiency more than Fq (q is a prime) or F2n.

We describe an index for estimating the level of interest in Web pages. This "time-based interest" (TBI) index combinates an equation reflecting page accesses and an equation reflecting the decrease in interest over time. These equations work simultaneously by using a parameter that is based on the time since the last access. We experimentally estimated the decrease ratio of the TBI index and evaluated the characteristics of the TBI equation. We found that the index follows Zipf's distribution, indicating that reflects the change in popularity. We also introduce an access-log analysis system called CyberRanking that includes TBI analysis. CyberRanking analyzes the access logs of Web servers and presents the results in 2-D or 3-D graph on a Web browser.

II-VI laser diode was fabricated using a ZnCdSe/ZnS0.06Se0.94/ZnMgSSe SCH structure on GaAs, in which ZnMgSSe was originally proposed by our group. ZnMgSSe is lattice-matched to GaAs and the bandgap energy of ZnMgSSe is larger than that of ZnSe and ZnS0.06Se0.94 lattice-matched to GaAs. As for the crystal growth mechanism, the composition of ZnMgSSe is not changed and the RHEED pattern becomes spotty in group II-rich growth conditions and S incorporation is difficult in group VI-rich growth conditions. From these results, we consider that the optimized growth condition of ZnMgSSe is in the stoichiometric region (both (21) and c(22) were observed). As for the device quality, although the current density of this device is minimized to 500 A/cm2, it was difficult to improve the reliability of the electrode and the active layer ZnCdSe. We found that the thin ZnTe and thick ZnSSe based electrode is necessary for reliability of the electrode, and that an optimized VI/II ratio is necessary for the reliability of the active region. To fabricate a relatively low-operating-voltage device, the stripe width is also an important parameter. In spite of relatively weak covalent bond of II-VI compounds, we can produce a device lifetime as long as 400 h.

This study is to clear how the impedance and the current of a simple printed line model involve to the near field electromagnetic noise radiation, by computer simulation and experiment. Frequency characteristics of the impedance and the current of the printed line and the near field noise are considered, from low to high frequency components. The model size 225 60 0.51 mm3, length of the line is 185 5 mm2 and 1 kΩ termination resistance is connected as non-matching load. FDTD method is used to calculate the impedance, the current waveform and the near field noise. Measurements of the line impedance and the near field noise spectrum by clock pulse are compared with simulations. It is cleared that using FDTD method, the characteristic of impedance of the printed line model, the current waveform, and the near field noise can be calculated at the same simulator. As results, from calculation and measurement, the near field noise has a relationship with impedance of printed line model. Emission at frequency less than 200 MHz, which is near the wavelength of λ/4, is observed at significant intensity. So, it is suggested that near field noise emission should be discussed from low to high frequency and analysis of the characteristics of the printed line and magnetic near field noise using FDTD method and measurement is useful to basic examination of complex PCB models.

For measuring high frequency ultrasonic fields which are often spatially distributed and transient, an array probe with small element sensors is highly required. In this paper, we propose a fiber-optic micro-probe array which is based on wavelength-division-multiplexing technique. The element sensor consists of a micro optical cavity of 100 µm long made at the end of optical fiber. Optical path length of the cavity is changed by the applied acoustic field, and the modulation of output light intensity is monitored at another end of the fiber for the information of the acoustic field. Array of sensor elements and a light source as well as a photo detector are connected together by an optical star coupler. The Fabry-Perot resonance wavelength of each sensor element is designed different one another, and the outputs from the sensors are discriminated by sweeping the wavelength of light source with the use of a tunable semiconductor laser. In this paper, the performance of the micro-probe array is discussed experimentally.

This paper shows quantitative evaluation of coupling between a monopole antenna outside a shield case and a strip line inside that for a portable telephone. The amount of the coupling is calculated using FDTD method together width EMF method. This combination of methods can raise the calculation efficiency. Dependence of the coupling on the length of gaps, the height of the strip line and the length of the antenna is clarified. The correspondence between calculated and measured results shows the validity of the calculation.