Ultrahigh-speed compact flash analog-to-digital converters (ADCs) using resonant-tunneling diodes (RTDs) have been designed to demonstrate a high potential of RTD circuits. Novel multi-input subtraction gates are introduced to the encoder to obtain a compact circuit configuration. By assuming 0.1-µm InP-based RTD/HEMT technology, circuit simulations of 4-bit 10-GHz flash ADCs are carried out. It is found that the device counts of the ADC with an 8-input gate are one third that of the ADC with 4-input gates. This leads to a reduction in the power dissipation by 50%. In addition, bandwidths of more than 20 GHz have been obtained for 4-bit and 5-bit ADCs at a sampling frequency of 10 GHz.

A batch process is a typical concurrent system in which multiple interacting tasks are carried out in parallel on several batches at the same time. A major difficulty in designing a batch control system is the lack of modeling techniques. This paper aims at developing a method of constructing batch control system models in a hierarchical manner and operating batch processes using the constructed models. For this purpose, it first defines process and plant specifications described by partial languages, next presents a procedure for constructing hierarchical Petri net based models, and states the verification of models based on reachability analysis. It also discusses the detection of faults and conflicts in batch processes based on place-invariant analysis.

In this letter, a circular microstrip patch antenna with a conical cup is proposed. The results of a simulation and experiment show that the conical cup has a beneficial effect on the antenna's gain and principal plane beamwidths. The maximum gain of this antenna was 12.6 dBi, which is about 3 dB higher than one with a cylindrical cup. The 3-dB beamwidths of the E-and H-planes were 34and 44, respectively.

LOTOS parallel operator, which is a binary operator, is used to combine processes in order to express their concurrency. Unlike other LOTOS operators, various possibilities exist when combining processes by the parallel operator. If two processes are selected randomly for combining, the size of the composite intermediate process after combining may be large. In this paper, we propose an algorithm for selecting two processes out of three or more processes so that the size of the intermediate process is the smallest when combined by the parallel operator. Smaller size of an intermediate process means it takes less memory space which is very important in designing verification tools for systems or communication protocols specified in LOTOS.

Electronic Toll Collection (ETC), an application of Dedicated Short Range Wireless Communication (DSRC), had suffered from wrong operations due to multipath problems. To solve this problem, we proposed to apply a simple configured path determination scheme for the ETC system. The system consists of a vector network analyzer, low-noise amplifier, and X-Y positioner and achieves an automatic measurement of the spatial transfer function with emphasis on accurate measurement and reproducibility. For the reliable identification of the propagating paths, 3-D Unitary ESPRIT and SAGE algorithms were employed. Having developed the system, field experiments at the toll gate of the highway was carried out. In the measurements, we could determine many propagation paths so that the dominant propagation phenomena at the toll gate was identified. They included a ground-canopy twice reflected wave, which was a potential path that caused wrong operation. Consequently, their reflection coefficients and polarization characteristics were investigated. From the results, applicability of the path determination system for short range on-site measurement was confirmed.

Our goal is to realize an extra-large stereoscopic display in the open air for use by the general public. We have developed a stereoscopic large display by use of a full-color LED panel. Although the developed display enables viewers to view the stereoscopic images without any special glasses, it is necessary for the viewers to move to stand within the viewing areas. Movements of the viewers are considered to depend on arrangements of viewing areas. The purpose of this paper is to investigate the movements of viewers who watch different designs of stereoscopic LED displays with a parallax barrier, including conventional designs to provide multiple perspective images and designs to eliminate pseudoscopic viewing areas, and evaluate the performance of different viewing areas based on the obtained paths of the viewers. We have developed a real-time measurement system of a viewer's position by use of a camera on the ceiling. We have recorded the viewing movements caused by the shift of viewing areas. It was found that the viewers moved to stand on orthoscopic viewing positions. The movements of viewers who move to find a viewing area have been recorded with different designs of stereoscopic LED displays that provide different viewing areas. We have calculated the lateral moving time of the viewers'movements. It is shown that the elimination of pseudoscopic viewing areas reduces the lateral moving time. Thus, the real-time measurement system of a viewer's position has been utilized for evaluation of performance of the different designs of stereoscopic LED displays.

To fulfill the computing demands in visual media processing, we have been investigating a parallel processing system to improve the processing speed of the visual media related to applications from the point of view of a memory system within a single instruction multiple data (SIMD) computer. In this paper, we have introduced MAMS-PP4, which is similar to a pipelined SIMD architecture type and consists of pq processing elements (PEs) as well as a multi-access memory system (MAMS). MAMS supports simultaneous access to pq data elements within a horizontal (1 pq), a vertical (pq 1) or a block (p q) subarray with a constant interval in an arbitrary position in an M N array of data elements, where the number of memory modules, m, is a prime number greater than pq. MAMS reduces the memory access time for an SIMD computer and also improves the cost and complexity that involved in controlling the large volume of data demanded in visual media applications. PE is designed to be a two-state machine in order to utilize MAMS efficiently. MAMS-PP4 was fabricated into ASIC using TOSHIBA TC240C series library and a test board was used to measure the performance of ASIC. The test board consists of devices such as an MPC860 embedded-PCI board, two ASICs and a FPGA for the control units. Experiment was done on various computer systems in order to compare the performance of MAMS-PP4 using morphological operations as the application. MAMS-PP4 shows a respectful and consistent processing speed.

An efficient VLSI architecture for 1-D lifting DWT is proposed in this paper. To achieve higherhardware utilization and higher throughput, the computations of all resolution levels are folded to both the same high-pass and low-pass filters. Besides, the number of registers in the folded architecture is minimized by using the generalized lifetime analysis. Owing to its regular and flexible structure, the design can be extended easily into different resolution levels, and its area is independent of the length of the 1-D input sequence. Compared with other known architectures, our design requires the least computing time for 1-D lifting DWT.

In this paper, we present a new numerical method for the complex approximation of FIR digital filters. Our objective is to design FIR filters with equiripple magnitude and phase errors. The proposed method solves the least squares (LS) problem iteratively. At each iteration, the desired response is updated so as to have an equiripple error. The proposed methods do not require any time-consuming optimization procedure such as the quasi-Newton methods and converge to equiripple solutions quickly. We show some examples to illustrate the advantages of our proposed methods.

Some conventional beamformers require the direction of the desired signal. The performance of such beamformers can substantially be degraded even in the presence of small error on the directional information. In this letter, we propose a prefilter-type beamforming scheme robust to directional error by employing a simple compensator. The performance of the proposed scheme is verified by computer simulation.

Imaging techniques for robots are important and meaningful in the near future. Pulse radar systems have a great potential for shape estimation and locationing of targets. They have an advantage that they can be used even in critical situations where optical techniques cannot be used. It is thus required to develop high-resolution imaging algorithms for pulse radar systems. High-resolution imaging algorithms utilize the carrier phase of received signals. However, their estimation accuracy suffers degradation due to phase rotation of the received signal because the phase depends on the shape of the target. In this paper, we propose a phase compensation algorithm for high-resolution pulse radar systems. The proposed algorithm works well with SEABED algorithm, which is a non-parametric algorithm of estimating target shapes based on a reversible transform. The theory is presented first and numerical simulation results follow. We show the estimation accuracy is remarkably improved without sacrificing the resolution using the proposed algorithm.

We propose a multiple-subcarrier (MS) optical communication system using intensity modulation with direct detection (IM/DD) with peak reduction carriers (PRCs) to improve the power efficiency of IM/DD MS systems. The proposed system transmits L subcarriers referred to as PRCs among N subcarriers for the d.c. bias reduction so that the optical power is reduced. Since information bits are mapped onto each subcarrier other than PRCs independently, the information bits of each subcarrier can be detected independently and the error rate of the proposed system is unaffected by PRCs.

Circuit techniques to realize stable recall operation and virtually unlimited read/program cycle operations in ferroelectric memory based nonvolatile (NV) SRAM composed of six-transistor and four-ferroelectric capacitor cells have been developed. Unlimited program cycle operation independent of ferroelectric material characteristics is realized by proper control of plate lines. Reliability evaluation results show that the developed memory cell has sufficient operation margin after stresses of temperature, fatigue, DC bias. Application of NV-SRAM to programmable logic devices has been discussed with a prototype of dynamically programmable gate arrays.

In this paper, we propose a formal method for detection of three automation surprises in human-machine interaction; a mode confusion, a refusal state, and a blocking state. The mode confusion arises when a machine is in a different mode from that anticipated by the user, and is the most famous automation surprise. The refusal state is a situation that the machine does not respond to a command the user executes. The blocking state is a situation where an internal event occurs, leading to change of an interface the user does not know. In order to detect these phenomena, we propose a composite model in which a machine and a user model evolve concurrently. We show that the detection of these phenomena in human-machine interaction can be reduced to a reachability problem in the composite model.

Masqueraders who impersonate other users pose serious threat to computer security. Unfortunately, firewalls or misuse-based intrusion detection systems are generally ineffective in detecting masqueraders. Anomaly detection techniques have been proposed as a complementary approach to overcome such limitations. However, they are not accurate enough in detection, and the rate of false alarm is too high for the technique to be applied in practice. For example, recent empirical studies on masquerade detection using UNIX commands found the accuracy to be below 70%. In this research, we performed a comparative study to investigate the effectiveness of SVM (Support Vector Machine) technique using the same data set and configuration reported in the previous experiments. In order to improve accuracy of masquerade detection, we used command frequencies in sliding windows as feature sets. In addition, we chose to ignore commands commonly used by all the users and introduce the concept of voting engine. Though still imperfect, we were able to improve the accuracy of masquerade detection to 80.1% and 94.8%, whereas previous studies reported accuracy of 69.3% and 62.8% in the same configurations. This study convincingly demonstrates that SVM is useful as an anomaly detection technique and that there are several advantages SVM offers as a tool to detect masqueraders.

An experimental model of a redox microarray, which provides a foundation for constructing future massively parallel molecular computers, is proposed. The operation of a redox microarray is confirmed, using an experimental setup based on an array of microelectrodes with analog integrated circuits.

This letter develops a practical sectorized antenna array using center-fed half-wavelength dipole antennas that are parallel to and a distance in front of a large ground plane reflector. Each element in the array is designed to provide coverage to isolate each 120sector from adjacent sectors. We derive a closed-form expression for spatial correlation function that can be used as guides in evaluating the effects of array spatial correlation on diversity performance in sectorized cellular communications.

The optimum tier architectures for ASICs are investigated by using a methodology for predicting packing efficiency of a logic block (the ratio of total cell area to the block area including space regions between cells). In the methodology based on Rent's rule, (1) the empirical parameters required for the prediction are derived from the results of our ASIC products. (2) The concept of logic distance, which is expressed in units of the number of cells rather than the absolute net length, is introduced. (3) Not only performance constraints but also reliability constraints are incorporated. These allow us to make a quantitative comparison of the packing efficiency between various cell and tier structures. It is found that, for mega-cell blocks, all minimum-pitch layer architecture with buffer insertion is expected to give more than 20% reduction in block areas compared to the minimum-pitch + bi-pitch architecture, while satisfying the performance and reliability constraints.

A double surface light emission backlight that uses single light-guide plate, has been developed for illumination of two liquid-crystal displays (LCD) on its front and rear, to be used in a cellular phone. The light-guide plate has a trapezoid cross-section with arrays of optical micro deflector and micro prism on the front and the rear surfaces, respectively. Propagated light, forward and backward, inside the light-guide plate are controlled and directed toward LCDs using only two prism sheets with internal reflection characteristic, each for the front and the rear. Only three optical components and four light-emitting diodes (LEDs) are used in the new structure compared with ten components and six LEDs of the current type. Comparing with the current type, the thickness and power consumption of the new backlight are reduced by a factor of 0.59 and 0.67, respectively.

In this paper, a sub-optimal Rake receiver combined with a Wiener Filter is investigated for use in an indoor environment. Inner-Chip-interference is dominant when the application is indoors, so the inner-chip-interference rejection function becomes critical for the receiver. Pilot symbols in each slot are used for channel estimation and weight calculation of Rake combining through Wiener Filter. Compared to conventional combining which uses maximum ratio combining, Wiener combining using IRC (Interference rejection combining) achieves better ICI (Inner-chip-Interference) rejection. This paper clarified that the sub optimal Rake receiver using Wiener Filter is 4 dB better than the conventional Rake receiver under the indoor application.