This paper presents a method for synthesizing a coherent 1-input 3-output optical delay-line circuit with N stages that is composed of 2(N + 1) directional couplers, N optical delay-lines, 2(N + 1) phase shifters and one external phase shifter with phase value φc . The path difference is equal to the delay time difference Δτ. Synthesis algorithm is based on the division of the transfer matrix into basic component transfer matrices and factorization is completed by repeated size-reduction. A set of recursion equations are also defined to obtain the unknown circuit parameters. In the developed method, it is shown that (13) optical delay-line circuit has the same transmission characteristics as finite impulse response (FIR) digital filters with complex expansion coefficients. Band-pass flat group delay type filter is considered as an example in this paper. It is also confirmed that developed (13) optical delay-line circuit can realize 100% power transmittance.

A lithium niobate (LiNbO3)/silicon (Si) hybrid structure has been developed by the surface-activated bonding of LiNbO3 chips with gold (Au) thin film to Si substrates with patterned Au film. After organic contaminants on the Au surfaces were removed using argon radio-frequency plasma, Au-to-Au bonding was carried out in ambient air. Strong bonding at significantly low temperatures below 100 without generating cracks has been demonstrated.

It is well-known that one of the best wavelet-based image compression techniques, called Wavelet Difference Reduction-WDR, has both simple algorithm and comparative rate-distortion results comparing to other coders in the literature. In this paper, we propose an algorithm to enhance the performance of WDR coder in a very efficient way. The methodology is highly based on the context adaptive model. High-order statistical context modeling is used for significant coefficients prediction by scanning order adaptation of WDR. In binary mode, the coder is clearly better than Set Partitioning in Hierarchical Trees (SPIHT). A new conditional Arithmetic Coding (AC) using array of contexts is specifically designed for WDR-based coder. Based on our simulation results of all images in the test set which covers various types of images, it is apparent that our proposed coder in AC mode generates the rate-distortion results that are superior to those of all other WDR-based coders in the literature. Furthermore, it is very competitive to SPIHT-AC and JPEG2000, the best coders, at all bit rates.

This paper studies the reduction among cyptographic functions. Our main result is that the prime factoring function IF does not reduce to the certified discrete logarithm function modulo a prime nor its variant with respect to some special reducibility, i.e. the range injection reducibility, under the assumption that the Heath-Brown conjecture is true and IFPF. Since there is no known direct relationship between these functions, this is the first result that could separate these functions. Our approach is based on the notion of the preimage functions.

We determine the annealing dynamics of AsGa antisite defects in As ion-implanted GaAs. An Arrhenius plot of the carrier decay rate or the defect density vs. the annealing temperature in the high temperature regime gives an energy EPA, which is different from true activation energy. The annealing time dependence of EPA obtained by the two diffusion models (self diffusion of AsGa antisite defects and VGa vacancy assisted diffusion of AsGa antisite defects) are compared with EPA's obtained from already published works. The results prove that the diffusion of AsGa antisite defects is assisted by the VGa vacancy defects that exist in a high density.

A typical watermarking scheme consists of an embedding scheme and a detection scheme. In detecting a watermark, there are two kinds of detection errors, a false positive error (FPE) and a false negative error (FNE). A detection scheme is said to be optimum if the FNE probability is minimized for a given FPE probability. In this paper, we present an optimum watermark detection scheme for an additive embedding scheme with a spatial domain. The key idea of the proposed scheme is to use the differences between two brightnesses for detecting a watermark. We prove that under the same FPE probability the FNE probability of the proposed optimum detection scheme is no more than that of the previous optimum detection scheme for the additive embedding scheme with the spatial domain. Then, it is confirmed that for an actual image, the FNE probability of the proposed optimum detection scheme is much lower than that of the previous optimum detection scheme. Moreover, it is confirmed experimentally that the proposed optimum detection scheme can control the FPE probability strictly so that the FPE probability is close to a given probability.

In this paper, the thermal characteristic of the GaN HFETs has been analyzed using the hybrid finite element method (FEM). Both the steady and transient state thermal operations are quantitatively studied with the effects of temperature-dependent thermal conductivities of GaN and the substrate materials properly treated. The temperature distribution and the maximum temperatures of the HFETs operated under excitations of continuous-waves (CW) and pulsed-waves (PW) including double exponential shape PW such as electromagnetic pulse (EMP) and ultra-wideband (UWB) signal are studied and compared.

We propose and demonstrate wavelength-selectable filters available for 32 WDM channels using a micro-mechanically movable mechanism with miniaturized voice-coil motors (VCMs). A simple straight geometry with a staggered configuration is used to densely pack 32 in/out moving elements into a small space of 452411 mm. The elements are precisely arranged along a collimated beam between fiber facets to provide flat-top passbands centered at ITU-T grids while maintaining small total insertion losses of less than 2.5 dB for all elements. The driving condition of the VCMs is also optimized for quick dynamic response with typical settling time of less than 10 ms. A repetition test 106 repetitions per element showed good wavelength reproducibility to an accuracy of below 0.1 nm, indicating the switches are feasible for practical system equipped with reconfigurable functionality for the next generation of optical networks.

The UWB (ultra-wideband) pulse radar is a promising candidate as an environment measurement method for rescue robots. Radar imaging to locate a nearby target is known as an ill-posed inverse problem, on which various studies have been done. However, conventional algorithms require long computational time, which makes it difficult to apply them to real-time operations of robots. We have proposed a fast radar imaging algorithm, the SEABED algorithm, for UWB pulse radars. This algorithm is based on a reversible transform, BST (Boundary Scattering Transform), between the target shape and the observed data. This transform enables us to estimate target shapes quickly and accurately in a noiseless environment. However, in a noisy environment the image estimated by the SEABED algorithm is degraded because BST utilizes differential operations. We have also proposed an image stabilization method, which utilizes the upper bound of the smoothness of received data. This method can be applied only to convex objects, not to concave ones. In this paper, we propose a fractional BST, which is obtained by expanding the conventional BST, and an image stabilization method by using the fractional BST. We show that the estimated image can be stabilized regardless of the shape of target.

The relationship between the topology and collective function of a nonlinear oscillator network was investigated using nonlinear electrochemical oscillators. The constitutive experiments showed that the physiological robustness in the living system is due to their topological redundancy and asymmetry in the nonlinear network.

A Non-Uniform Discrete Multitone (DMT) transceiver employing an octave spaced quadrature mirror filter (QMF) bank, can be used to overcome the problem of channel noise enhancement in the zero-forcing (ZF) equalization technique. In this letter, performance of the Non-Uniform DMT system is analyzed. A study of the crosstalk between sub-channels due to non-ideal filter banks is also presented. Crosstalk analysis is based upon the bit error rate (BER) performance versus the QMF order in a standadard ADSL channel. Performance comparison of the Non-Uniform DMT transceiver and a conventional DMT system is given, and it is shown that the Non-Uniform DMT transceiver displays slight improvement over the conventional DMT system for the filters of higher order.

The coexistence of MPEG-2 and its powerful successor H.264/AVC has created a huge need for MPEG-2/H.264 video transcoding. However, a traditional transcoder where an MPEG-2 decoder is simply cascaded to an H.264 encoder requires huge computational power due to the adoption of a complicated rate-distortion based mode decision process in H.264. This paper proposes a 2-D Sobel filter based motion vector domain method and a DCT domain method to measure macroblock complexity and realize content-based H.264 candidate mode decision. A new local edge based fast INTRA prediction mode decision method is also adopted to boost the encoding efficiency. Simulation results confirm that with the proposed methods the computational burden of a traditional transcoder can be reduced by 20%30% with only a negligible bit-rate increase for a wide range of video sequences.

This letter develops an efficient CPM demodulator which provides soft outputs for use in coded CPM. The proposed algorithm offers reduced-complexity soft output detection in which the number of matched filters and trellis states is appreciably reduced. The complexity reduction is achieved by approximating the CPM signal using the Laurent representation. A simulation study of iterative decoding of serially concatenated CPM with an outer code was performed. The performance degradation of the proposed algorithm relative to optimal full complexity generation of soft outputs was found to be small.

In this paper, we apply iterative detection to typical time hopping (TH) pulse position modulation (PPM) ultra wideband (UWB) spread spectrum systems. Unlike a typical TH-PPM UWB which employs repetition code, the proposed system uses self-encoded code which is updated by user information itself. To take advantage of self-encoded spread spectrum, we apply iterative detection to the TH-PPM UWB system. Simulations are conducted to investigate the bit error rate (BER) performance of the proposed system in additive white gaussian noise (AWGN) channels as well as in fading and multipath channels. We observe a significant BER performance improvement over conventional TH-PPM UWB systems.

The performance of a force feedback system is disturbed by delay that arises from the time required for transmission and processing of data. We used a psychophysical method to measure how much a user's subjective impression of elasticity associated with delays of feedback force deviated from the original physical elasticity. The results show that users' point of subjective equality (PSE) for their subjective impression of elasticity decreased as the delay of feedback force increased. We proposed a model that estimates the PSE of elasticity from the variables that can be physically measured. Another experiment was conducted to examine the model's prediction, which the results supported.

Password-based authenticated key exchange protocols are more convenient and practical, since users employ human-memorable passwords that are simpler to remember than cryptographic secret keys or public/private keys. Abdalla, Fouque, and Pointcheval proposed the password-based authenticated key exchange protocol in a 3-party model (GPAKE) in which clients trying to establish a secret do not share a password between themselves but only with a trusted server. On the other hand, Canetti presented a general framework, which is called universally composable (UC) framework, for representing cryptographic protocols and analyzing their security. In this framework, the security of protocols is maintained under a general protocol composition operation called universal composition. Canetti also proved a UC composition theorem, which states that the definition of UC-security achieves the goal of concurrent general composition. A server must manage all the passwords of clients when the 3-party password-based authenticated key exchange protocols are realized in large-scale networks. In order to resolve this problem, we propose a hierarchical hybrid authenticated key exchange protocol (H2AKE). In H2AKE, forwarding servers are located between each client and a distribution server, and the distribution server sends the client an authentication key via the forwarding servers. In H2AKE, public/private keys are used between servers, while passwords are also used between clients and forwarding servers. Thus, in H2AKE, the load on the distribution server can be distributed to the forwarding servers concerning password management. In this paper, we define hierarchical hybrid authenticated key exchange functionality. H2AKE is the universal form of the hierarchical (hybrid) authenticated key exchange protocol, which includes a 3-party model, and it has the characteristic that the construction of the protocol can flexibly change according to the situation. We also prove that H2AKE is secure in the UC framework with the security-preserving composition property.

The element-by-element finite element method (EBE-FEM) combined with the preconditioned conjugate gradient (PCG) technique is employed in this paper to calculate the coupling capacitances of multi-level high-density three-dimensional interconnects (3DIs). All capacitive coupling 3DIs can be captured, with the effects of all geometric and physical parameters taken into account. It is numerically demonstrated that with this hybrid method in the extraction of capacitances, an effective and accurate convergent solution to the Laplace equation can be obtained, with less memory and CPU time required, as compared to the results obtained by using the commercial FEM software of either MAXWELL 3D or ANSYS.

To make the best use of the resources in a shared grid environment, an application scheduler must make a prediction of available performance on each resource. In this paper, we examine the problem of predicting available CPU performance in time-shared grid system. We present and evaluate a new and innovative method to predict the one-step-ahead CPU load in a grid. Our prediction strategy forecasts the future CPU load based on the variety tendency in several past steps and in previous similar patterns, and uses a polynomial fitting method. Our experimental results on large load traces collected from four different kinds of machines demonstrate that this new prediction strategy achieves average prediction errors which are between 22% and 86% less than those incurred by four previous methods.

A tri-template-based codes (TTBC) method is proposed to reduce test cost of intellectual property (IP) cores. In order to reduce test data volume (TDV), the approach utilizes three templates, i.e., all 0, all 1, and the previously applied test data, for generating the subsequent test data by flipping the inconsistent bits. The approach employs a small number of test channels I to supply a large number of internal scan chains 2I-3 such that it can achieve significant reduction in test application time (TAT). Furthermore, as a non-intrusive and automatic test pattern generation (ATPG) independent solution, the approach is suitable for IP core testing because it requires neither redesign of the core under test (CUT) nor running any additional ATPG for the encoding procedure. In addition, the decoder has low hardware overhead, and its design is independent of the CUT and the given test set. Theoretical analysis and experimental results for ISCAS 89 benchmark circuits have proven the efficiency of the proposed approach.

Conditional random fields (CRFs) have been successfully applied to various applications of predicting and labeling structured data, such as natural language tagging & parsing, image segmentation & object recognition, and protein secondary structure prediction. The key advantages of CRFs are the ability to encode a variety of overlapping, non-independent features from empirical data as well as the capability of reaching the global normalization and optimization. However, estimating parameters for CRFs is very time-consuming due to an intensive forward-backward computation needed to estimate the likelihood function and its gradient during training. This paper presents a high-performance training of CRFs on massively parallel processing systems that allows us to handle huge datasets with hundreds of thousand data sequences and millions of features. We performed the experiments on an important natural language processing task (text chunking) on large-scale corpora and achieved significant results in terms of both the reduction of computational time and the improvement of prediction accuracy.