We describe a layer 3 diversity reception scheme that enhances the transmission characteristics of Ku-band mobile satellite communication systems. This scheme can realize high-speed communication for vehicles that experience shadowing caused by terrestrial obstacles such as tunnels, buildings and bridges, especially for trains that frequently experience shadowing from the trolley wire structures. Layer 3 diversity was chosen for long distance diversity to prevent signal shadowing caused by terrestrial obstacles while minimizing the alterations of existing receivers. The technology enables high-speed communication under shadowing conditions in a running train environment.

This study investigates a band extension technique for speech data encoded with G.711, the most common codec for digital speech communications system such as VoIP. The proposed technique employs steganography for the transmission of the side information required for the band extension. Due to the steganography, the proposed technique is able to enhance the speech quality without an increase of the amount of data transmission. From the results of a subjective experiment, it is indicated that the proposed technique may potentially be useful for improving the speech quality, compared with the conventional technique.

A clock and data recovery (CDR) circuit using a new half-rate wide-range phase detection technique has been developed. Unlike the conventional three-state phase detectors, the proposed detector is applicable to the Non-Return-to-Zero (NRZ) data stream and also has low jitter and wide capture range characteristics. The CDR circuit was implemented in a 0.35-µm N-well CMOS technique. Experimental results demonstrate that it can achieve the peak-to-peak jitter of the recovered clock and the retimed data about 120 ps and 170 ps, respectively, while operating at the input data rate of 1 Gb/s. The total power dissipation of the CDR is 64.8 mW for the supply 3 V.

Visualizing occluded objects is a useful applications of Mixed Reality (MR), which we call "see-through vision." For this application, it is important to display occluded objects in such a manner that they can be recognized intuitively by the user. Here, we evaluated four visualization methods for see-through vision that can aid the user to recognize occluded objects in outdoor scenes intuitively: "elimination of occluding objects," "ground grid," "overlaying model of occluding object," and "top-down view." As we used a new handheld MR device for outdoor see-through vision, we performed subjective experiments to determine the best combination of methods. The experimental results indicated that a combination of showing the ground grid, overlaying wireframe models of occluding objects, and top-down view to be optimal, while it was not necessary to display occluding objects for outdoor see-through vision with a handheld device, because users can see them with the naked eye.

In this paper, the confinement loss of octagonal photonic crystal fibers (PCFs) with an isosceles triangle lattice of air-holes are numerically investigated. Taking into account the confinement loss, the mode field diameter (MFD), the effective area (Aeff) and the chromatic dispersion of octagonal PCFs are calculated, compared to conventional hexagonal PCFs. It is found from confinement loss and MFD results that the octagonal PCFs can confine the field strongly than the hexagonal PCFs due to the different air filling fraction. Moreover, it is shown that the octagonal PCFs are obtained not only positive but also negative larger dispersion values and smaller Aeff values compared to the hexagonal PCFs.

This paper proposes a low power scan test scheme and formulates a problem based on this scheme. In this scheme the flip-flops are grouped into N scan chains. At any time, only one scan chain is active during scan test. Therefore, both average power and peak power are reduced compared with conventional full scan test methodology. This paper also proposes a tabu search-based approach to minimize test application time. In this approach we handle the information during deterministic test efficiently. Experimental results demonstrate that this approach drastically reduces both average power and peak power dissipation at a little longer test application time on various benchmark circuits.

The present research examines the relationship between texture processing and object processing in human vision. Recent computational studies have suggested a difference between the stages of processing. Texture processing can be performed by using statistical parameterization of the response of primary spatial filters. Object processing requires more complex and elaborate computation at a higher stage than texture processing. Our psychophysical experiments are conducted to clarify the relationship of the stages of texture processing and object processing, by focusing on same-object effect which facilitates and speeds attention shifts within the same object and also costs and delays attention shifts if the attention focus moves from one object to another. Texture is composed of lines parallel to, perpendicular to or inside of elongated rectangles used as objects. The same-object effect is measured with reaction time in a cued detection task. Vertical rectangles are used in xperiment 1 and horizontal ones are used in Experiment 2. Experiment 1 shows that the texture lines interrupt the same-object effect and that the interruption is nearly equal if texture lines are added both to the background and the inside of the objects. Experiment 2 yields the result same as Experiment 1. The interruption of the same-object effect by adding texture lines suggests that texture processing affects object processing.

A new simply implemented collusion-attack free identity-based non-interactive key sharing scheme (ID-NIKS) has been proposed. A common-key can be shared by executing only once a modular exponentiation which is equivalent to RSA deciphering, and the security depends on the difficulty of factoring and the discrete logarithm problem. Each user's secret information can be generated by solving two simple discrete logarithm problems and synthsizing their solutions by linear combination. The detail comparison with the Maurer-Yacobi's scheme including its modified versions shows that the computational complexity to generate each user's secret information is much smaller and the freedom to select system parameters is much greater than that of the Maurer-Yacobi's scheme. Then our proposed scheme can be implemented very easily and hence it is suitable for practical use.

Electrical capacitance tomography (ECT) is used to obtain information about the distribution of a mixture of dielectric materials inside a vessel or pipe. ECT has several advantages over other reconstruction algorithms and has found many applications in the industrial fields. However, there are some difficulties with image reconstruction in ECT: The relationship between the permittivity distribution and measured capacitance is nonlinear. And inverse problem is ill-posed so that the inverse solution is sensitive to measurement error. To cope with these difficulties iterative image reconstruction algorithms have been developed. In general, the iterative reconstruction algorithms in ECT have comparatively good-quality in reconstructed images but result in intensive computational burden. This paper presents the iterative image reconstruction algorithm for ECT that can enhance the speed of image reconstruction without degradation in the quality of reconstructed image. The main contribution of the proposed algorithm is new weighting matrices, which are obtained by the interpolation of the grouped electrical field centre lines (EFCLs). Extensive simulation results have demonstrated that proposed algorithm provides improved reconstruction performance in terms of computational time and image quality.

This paper presents a new statistical model-based voice activity detection (VAD) algorithm in the wavelet domain to improve the performance in non-stationary environments. Due to the efficient time-frequency localization and the multi-resolution characteristics of the wavelet representations, the wavelet transforms are quite suitable for processing non-stationary signals such as speech. To utilize the fact that the wavelet packet is very efficient approximation of discrete Fourier transform and has built-in de-noising capability, we first apply wavelet packet decomposition to effectively localize the energy in frequency space, use spectral subtraction, and employ matched filtering to enhance the SNR. Since the conventional wavelet-based spectral subtraction eliminates the low-power speech signal in onset and offset regions and generates musical noise, we derive an improved multi-band spectral subtraction. On the other hand, noticing that fixed threshold cannot follow fluctuations of time varying noise power and the inability to adapt to a time-varying environment severely limits the VAD performance, we propose a statistical model-based VAD algorithm in wavelet domain with an adaptive threshold. We perform extensive computer simulations and compare with the conventional algorithms to demonstrate performance improvement of the proposed algorithm under various noise environments.

Content-based publish/subscribe systems provide a useful alternative to traditional address-based communication due to their ability to decouple communication between participants. It has remained a challenge to design a scalable overlay supporting the complexity of content-based networks, while satisfying the desirable properties large distributed systems should have. This paper presents the design of Mirinae, a new structured peer-to-peer overlay mesh based on the interests of peers. Given an event, Mirinae provides a flexible and efficient dissemination tree minimizing the participation of non-matching nodes. We also present a novel ID space transformation mechanism for balancing routing load of peers even with highly skewed data, which is typical of the real world. Our evaluation demonstrates that Mirinae is able to achieve its goals of scalability, efficiency, and near-uniform load balancing. Mirinae can be used as a substrate for content-search and range query in other important distributed applications.

In this letter, we derive an efficient audio/video synchronization method for video telephony. For synchronization, this method does not require any further RTCP packet processing except for the first one. The derived decision rule is far more compact than the conventional method. This decision rule is incorporated in an actual video telephony system adopting Texas Instruments (TI) OMAP 1510 processor and Qualcomm MSM 5500. The computational requirement was compared with the conventional method and through simulations the superiority of the proposed method is proved.

Usually an FIR filter is used to model the physical paths in an active noise control system. However, the order of the filter to be modeled is a key factor for determining the computational load for the adaptive algorithms associated with active noise control (ANC), particularly for multi-channel algorithms. In this letter, the relationships among the filter's order, the plant modeling error and the location of poles for the transfer functions of the physical paths in an ANC system are theoretically examined and numerical examples are given to verify the theoretical results.

We extend the adaptive-order rational Arnoldi algorithm for multiple-inputs and multiple-outputs (MIMO) interconnect model order reductions. Instead of using the standard Arnoldi algorithm for the SISO adaptive-order reduction algorithm (AORA), we study the adaptive-order rational global Arnoldi (AORGA) algorithm for MIMO model reductions. In this new algorithm, the input matrix is treated as a vector form. A new matrix Krylov subspace, generated by the global Arnoldi algorithm, will be developed by a Frobenius-orthonormal basis. By employing congruence transformation with the matrix Krylov subspace, the one-sided projection method can be used to construct a reduced-order system. It will be shown that the system moment matching can be preserved. In addition, we also show that the transfer matrix residual error of the reduced system can be derived analytically. This error information will provide a guideline for the order selection scheme. The algorithm can also be applied to the classical multiple point MIMO Pade approximation by the rational Arnoldi algorithm for multiple expansion points. Experimental results demonstrate the feasibility and the effectiveness of the proposed method.

A simple method for the gain improvement of matrix distributed amplifiers is presented. The method is based on modifying the central transmission line of the matrix amplifier without any changes in the input and output transmission lines. In the new method the termination impedances in the central transmission line are modified and the transmission line is replaced by an impedance matching circuitry. It has been shown that the new method can significantly improve the gain while preserving the input and output return losses of the amplifier.

This letter presents two high-performance level-converting flip-flops (LCFF) for multi-VDD systems, indirect precharging flip-flop (IPFF) and multi-supply complementary pass-transistor flip-flop (MCPFF). Employing a simple precharging scheme, IPFF provides high operating speed. MCPFF, on the other hand, provides low power operations by implementing the edge-triggering function with complementary pass transistors. Performance comparison indicates that IPFF operates at the highest speed and MCPFF consumes the lowest power among the seven LCFFs under evaluation.

Among the broadband wireless communication standards utilized to satisfy the demand for multimedia services, time division duplexing (TDD) is satisfactory for the asymmetric data transmission emphasized in Internet services. In this system, the transition between receiving a frame and transmitting a response must be bounded for an effective use of radio resources. However, the minimized inter-frame space-time requires high processing power. The aim of the present paper is to gain insight into the time latency at the turn-around time of a TDD operation. We also propose a simplified new processor, which is a terminal device-friendly architecture that includes prediction and preparation to support processing of burst-type traffic.

High-resolution FMCW reflectometry is often realized by sampling the beat signal with a clock signal generated from an auxiliary interferometer. The drawback of this system is that the measurement range is limited to less than half of the optical path difference of the auxiliary interferometer to satisfy the Sampling theorem. We propose and demonstrate a method to extend the measurement range of the system. The clock signal gerenerated from the auxiliary interferometer is electronically frequency-multipled by using a PLL circuit. The measurement range is experimentally extended by a factor of 20 while keeping high spatial resolution, and is theoretically extended by a factor of 128. The advantage of the proposed system is that the optical path difference of the auxiliary interferometer can be kept short, which is very effective for obtaining the stable and low time-jitter clock signal.

A method using an averaging technique for the analysis and evaluation of real quasi-resonant converters (QRC's) is proposed in this paper. To reduce the great difference between the real characteristics and those of ideal circuits, a modeling technique is developed by considering the effect of parasitic power losses. Then, using the averaging approach reasonably simplifies the process of solving equations to obtain the steady-state solutions of state variables. Also, an updating algorithm is constructed to take all the power losses such as core losses, which are often absent in the conventional analysis, into account to improve the accuracy of the steady-state solutions. By these efforts, the evaluation of characteristics for QRC's is realized.

We describe attempts to have robots behave as embodied knowledge media that will permit knowledge to be communicated through embodied interactions in the real world. The key issue here is to give robots the ability to associate interactions with information content while interacting with a communication partner. Toward this end, we present two contributions in this paper. The first concerns the formation and maintenance of joint intention, which is needed to sustain the communication of knowledge between humans and robots. We describe an architecture consisting of multiple layers that enables interaction with people at different speeds. We propose the use of an affordance-based method for fast interactions. For medium-speed interactions, we propose basing control on an entrainment mechanism. For slow interactions, we propose employing defeasible interaction patterns based on probabilistic reasoning. The second contribution is concerned with the design and implementation of a robot that can listen to a human instructor to elicit knowledge, and present the content of this knowledge to a person who needs it in an appropriate situation. In addition, we discuss future research agenda toward achieving robots serving as embodied knowledge media, and fit the robots-as-embodied-knowledge-media view in a larger perspective of Conversational Informatics.