Multi-projector technology has been under consideration in recent years. This technology allows the generation of wide field of view and high-resolution images in a cost-effective manner. It is expected to be applied extensively to training simulators where vivid immersive sensations and precision are required. However, in many systems the viewing frustums cannot be automatically assigned for distributed rendering, and the required manual setup is complicated and difficult. This is because the camera should be coincide exactly with a desired eye point to avoid perspective distortions. For the actual applications, the camera is seldom able to be set up at the desired eye point because of physical constraints, e.g., a narrow cockpit with many instruments. To resolve this issue, we have developed a "virtual camera method" that yields high-precision calibration regardless of the camera position. This method takes advantage of the quadratic nature of the display surface. We developed a practical real-time multi-projector display system for applications such as training simulators, that require high-accuracy in geometry and rapid response time.

Double-sided YBa2Cu3O7 (YBCO) films were successfully prepared on 50-mm-diameter CeO2-buffered sapphire substrates by metalorganic deposition (MOD) process using an acetylacetonate coating solution. Mapping analysis of superconducting current densities (Jc) at 77.3 K revealed that Jc values of the double-sided films indicated in excess of 2 MA/cm2 in the center parts with a small decrease of Jc at the outer side of the specimens. The Jc values of one side (A) are higher than those of the other side (B). Microwave surface resistance (Rs) of sides A and B of the film exhibited 0.57 and 0.60 mΩ, respectively, at 70 K (12 GHz). The difference in the Rs values should be attributed to the slight difference in the Jc values, which arose from the surface morphology of the CeO2 buffer layer and heat treatment conditions during the firing process in MOD.

This paper presents a way of using a linear regression model to produce a single-valued criterion that indicates the perceived importance of each block in a stream of speech blocks. This method is superior to the conventional approach, voice activity detection (VAD), in that it provides a dynamically changing priority value for speech segments with finer granularity. The approach can be used in conjunction with scalable speech coding techniques in the context of IP QoS services to achieve a flexible form of quality control for speech transmission. A simple linear regression model is used to estimate a mean opinion score (MOS) of the various cases of missing speech segments. The estimated MOS is a continuous value that can be mapped to priority levels with arbitrary granularity. Through subjective evaluation, we show the validity of the calculated priority values.

This paper investigates zero pronouns in Korean, especially focusing on the center transitions of adjacent utterances under the framework of Centering Theory. Four types of nominal entity (Epair, Einter, Eintra, and Enon) from Centering Theory are defined with the concept of inter-, intra-, and pairwise salience. For each entity type, a case study of zero phenomena is performed through analyzing corpus and building a pronominalization model. This study shows that the zero phenomena of entities which have been neglected in previous Centering works are explained via the center transition of the second previous utterance, and provides valuable results for pronominalization of such entities, such as p2-trans rule. We improve the accuracy of pronominalization model by optimal feature selection and show that our accuracy outperforms the accuracy of previous works.

A novel low-voltage low-distortion analog sampling switch is proposed in this letter. A "source tracker" techniuqe is used to distinguish the real source terminal of the sampling switch. The turn-on resistance of the sampling switch is kept exactly constant. The modified switch makes the rail-to-rail input signal swing possible for low voltage. TSMC 0.18 µm standard CMOS technology is utilized in this research. Results indicate that much lower Total Harmonic Distortion (THD) is achieved by the proposed circuit. The low THD meets the requirements in the application of the low-voltage low-distortion switched-capacitor circuits.

This paper proposes a new approach for analog portion testing, which can meet requirements for high-speed and high-accuracy testing simultaneously with reasonable cost. The key concept of the new method is cooperation of an LSI tester and some circuitry built in a target SoC device. We will explain the operation principle of the proposed method. The proposed method can be one of the methods to overcome today's expensive production test of analog portion on SoC (System on Chip) devices which heavily depends on LSI tester capability and will become harder in near future.

Linearity of a transconductor with a theoretical linear characteristic is deteriorated by mobility degradation, in practice. In this paper, a technique to improve the linearity by combining a source-coupled pair with the transconductor is proposed. The proposed transconductor is the circuit that the deteriorated linearity of the conventional part is compensated by the transconductance characteristic of the source-coupled pair. In order to confirm the validity of the proposed technique, SPICE simulation is carried out. The transconductance change ratio of the proposed technique is about 1% and is 1/10 or less of the conventional circuit.

A four-quadrant-input linear transconductor generating a product or a product sum current is proposed. The proposed circuit eliminates the influence of channel length modulation and expands a dynamic input voltage range. As an application of the proposed circuit, the four-quadrant analog multiplier is designed. The four-quadrant analog multiplier consists of the proposed circuit, an input circuit and a class AB current buffer. HSPICE simulation results with 0.35 µm n-well single CMOS process parameter are shown in order to evaluate the proposed circuit.

The 2-terminal shortest path problem is to find a shortest path between two specified vertices in a given graph G. In this paper, we consider this problem in the following situation: G is given before the two vertices are specified so that some preprocessing is allowed to reduce the response time. We present a method for calculating lower bounds of the length of the shortest path for any pair of vertices. Experimental results show that the A* algorithm with our method performs much better than previous methods.

The performance of a feedback-type adaptive array antenna (AAA) system placed only at a base station (BS) in an FDD/DS-CDMA system remains insufficiently clear. We evaluate the performance of this system by considering the effect of a rake receiver, spacing distance between antennas, the maximum Doppler frequency (fd), and control delay time (Td) on BER performance. In this system, the mobile station (MS) determines optimum weights of antenna elements and sends them back to BS as feedback information. We assume that the optimum weights are not quantized. Thereby, we estimate the performance degradation of 3GPP transmit diversity system, where the feedback information is quantized using a few bits. Computer simulation results show that the rake receiver achieves better BER performance because of the time diversity effect with rake receiver. The AAA with a wide antenna spacing gives high diversity gain for the received signals. For a high value of fd Td, BER performance becomes worse because weighting factors cannot follow the changing speed of channel characteristics. The degradation in performance of a 3GPP system is clarified.

As process technologies decrease below a hundred nanometers, the variability of circuit parameters increases, and statistical timing analysis, which analyzes the distribution of the critical delay of a circuit, is receiving a great deal of attention. In such statistical approaches, correlations between random variables are important to the accuracy of analysis. Since interconnect delays dominate in recent technology, their correlations are of primary concern in statistical timing analysis. In this paper, we propose an efficient algorithm for calculating correlation coefficients between Elmore interconnect delays with the use of Gaussian distributions. Our algorithm is efficient and yields reasonable results for correlations between interconnect delays of different nets. In order to evaluate the performance of the proposed algorithm, we show experimental results compared against Monte-Carlo simulations using SPICE.

Based on the observation that foveation analysis can be used to find most critical content in terms of human visual perception in video and image, one effective error resilience method is proposed for robust transmission of H.264 intra-coded frame in wireless channel. It firstly exploits the results of foveation analysis to find foveated area in picture, and then considers the results of pre-error concealment effect analysis to search for the center of foveation macro-blocks (MB) in foveated area, finally new error resilient alignment order of MB and new coding order of MB are proposed that are used in video encoder. Extensive experimental results on different portrait video sequences over random bit error wireless channel demonstrate that this proposed method can achieve better subjective and objective effect than original JM 8.2 H.264 video codec with little effect on coding rate and image quality.

This paper describes the author's perspective on multimedia quality prediction methodologies for multimedia communications in advanced mobile and internet protocol (IP)-based telephony, and reports related experiments and trials. First, the paper describes the need for perceptual QoS (Quality of Service) assessment in which various quality factors in multimedia communications for advanced mobile and IP-based telephony are analyzed. Then an objective quality prediction scheme is proposed from the viewpoints of quality measurement tools for each quality factor and an opinion model for compound quality factors in mobile and IP-based communications networks. Finally, the author's current trials of measurement tools and opinion models are described.

A combination of horizontal expansion and vertical stacking of optical Banyan (HVOB) is the general architecture for building Banyan-based optical cross-connects (OXCs), and the intrinsic crosstalk problem of optical signals is a major constraint in designing OXCs. In this paper, we analyze the blocking behavior of HVOB networks and develop the lower bound on blocking probability of a HVOB network that is free of first-order crosstalk in switching elements. The proposed lower-bound is significant because it provides network designers an effective tool to estimate the minimum blocking probability they can expect from a HVOB architecture regardless what kind of routing strategy to be adopted. Our lower bound can accurately depict the overall blocking behavior in terms of the minimum blocking probability in a HVOB network, as verified by extensive simulation based on a network simulator with both random routing and packing routing strategies. Surprisingly, the simulated and theoretical results show that our lower bound can be used to efficiently estimate the blocking probability of HVOB networks applying packing strategy. Thus, our analytical model can guide network designers to find the tradeoff among the number of planes (stacked copies), the number of SEs, the number of stages and blocking probability in a HVOB network applying packing strategy.

iPat/OMP is an interactive parallelization assistance tool for OpenMP. In the present paper, we describe the design concept of iPat/OMP, the parallelization sequence achieved by the tool and its current implementation status. In addition, we present an evaluation of the performance of the implemented functionalities. The experimental results show that iPat/OMP can detect parallelism and create an appropriate OpenMP directive for several for-loops.

By applying the differential space-time block code (DSTBC) to wireless multicarrier transmission, Diggavi et al. were the first to propose the two-input-multiple-output (2IMO) differentially space-time-time block coded OFDM (TT-OFDM) system. In this paper, we propose three novel differentially transmit-diversity block coded OFDM (DTDBC-OFDM) systems, namely, the FT-, FF-, and TF-OFDM systems. For instance, the TF-OFDM stands for the differentially space-time-frequency block coded OFDM. Moreover, the noncoherent maximum-likelihood sequence detector (NSD), and its three special cases, namely, the noncoherent one-shot detector, the linearly predictive decision-feedback (DF) detector, and the linearly predictive Viterbi receiver are incorporated to the 2IMO DTDBC-OFDM systems. Furthermore, a simple closed-form BER expression for the systems utilizing the noncoherent one-shot detector in the time-varying multipath Rayleigh fading channels is given. Numerical results have revealed that 2IMO DTDBC-OFDM systems employing the noncoherent one-shot detector can obtain significant performance improvement. However, when few antennas are available, the implementation of the linearly predictive DF detector or the linearly predictive Viterbi receiver is necessary for achieving better performance.

A simple self-biased receiver system with a dual branch architecture consisting of a low-power consumption receiver and a rectenna is introduced. The system is efficiently integrated with a dual-fed circular sector antenna with harmonic rejection characteristics without a BPF. The receiver portion is designed by utilizing a low-noise amplifier (LNA) with low power consumption and a self-heterodyne mixer, while the rectenna achieves high conversion efficiency up to 80%, thanks to the harmonic rejection of the circular sector antenna. The rectified DC power from the rectenna is applied for a bias of the receiver without any external bias. Simultaneously, an ASK digital signal demodulation without an extra power supply are implemented successfully.

In this paper, routing properties of cube-based optoelectronic OTIS networks are explored. We show emulations of various cubical network topologies on their OTIS augmented variants, including the n-D grid networks, shuffle-exchange, and de Brujin networks. An analytical performance model for OTIS-cube networks is proposed. The model is validated by means of comparison with rigorously obtained simulation results. Using this model, the performance characteristics of the OTIS-hypercube network are evaluated in view of a number of different constraints. Moreover, we compare the performance characteristics of the OTIS-hypercube with that of equivalent fully-electronic networks under various implementation constraints.

Wireless sensor networks present a promising opportunity for realizing many practical applications. Tracking is one of the important applications of these networks. Many approaches have been proposed in the literature to deal with the tracking problem. Recently, a particular type of tracking problem called on-site tracking has been introduced [15],[16]. On-site tracking has been characterized as the tracking in which the sink is eventually required to be present in the vicinity of the target, possibly to perform further actions. In this paper, first we propose two efficient on-site tracking algorithms. Then, we derive theoretical upper bounds for the tracking time and the number of messages generated by the sensor nodes during the tracking for our algorithms. Finally, we present a simulation study that we conducted to evaluate the performance of our algorithms. The results show that our algorithms are efficient as compared to the other existing methods that can solve the on-site tracking problem. In particular, the path adaptive nature of the sink in our algorithms allows the network to conserve the energy and the sink to reduce the tracking time.

We describe three types of software-defined-radio (SDR) receivers based on superconducting technologies. The superconducting analog bandpass filters are essential for all types of the receivers. Another key component is an analog-to-digital converters (ADCs), which are required to have high resolution with a broad band width. The complementary Δ ADC based on the single-flux-quantum circuit is a promising candidate for the SDR receivers because it has a practical nature together with above-mentioned requirements. The experimentally obtained signal-to-noise ratio (SNR) and sensitivity, which are closely related to the resolution, are 34 dB and 20 µA for a quarter of the full-scale input with a band width of about 20 MHz. If we use the optimum decimation filter, the ADC is expected to have the SNR of 82 dB and the sensitivity of 300 nA. These values meet the requirements of the easiest type of the SDR receiver. After new fabrication process has been introduced and the architecture of the ADC has been improved, all types of recievers could be realized based on superconductors.