The reduction of undesired electromagnetic emissions in switched power converters is a hot topic. Here, we propose a chaos based methodology to synthesize PWM-like signals for controlling the drives of induction motors. This approach reduces drastically the interference due to the drive-motor ensemble, and does not significantly alter the motor performance. The benefit is a 20 dB reduction in the peak of the emitted power density spectrum. This result is herein confirmed three times: first with an analytical approach based on approximations whose impact is progressively reduced; then by means of simulation; finally by laboratory testing of a working prototype.

Synchronous Gaussian code-division multiple access (CDMA) systems employing group-orthogonal signature waveforms are proposed and analyzed. All users in the system are divided into groups of users. The signature waveforms are constructed such that all the signature waveforms in one group are orthogonal to all the signature waveforms used in all other groups. This construction of signature waveforms ensures that there is no inter-group interference (i.e., among users in different groups), but at the expense of having intra-group interference (i.e., among users in the same group). However, by choosing a small size for each group, the intra-group interference can be effectively handled by a low-complexity, optimal (or suboptimal) multiuser detector. It is shown that a significant improvement in the system capacity can be achieved by the proposed technique over the conventional one that uses signature waveforms constructed from Welch-bound-equality (WBE) sequences. In particular, it is demonstrated that, while the conventional system's error performance is very sensitive to even small amount of overload, the proposed system with an appropriate design of signature waveforms can achieve a much higher overload (up to 300% as shown in the paper) with an excellent error performance.

Thermal stability of stacked high-κ dielectrics, especially ZrO2, HfO2 and ZrSiO4 /SiO2 layered structures, on silicon has been investigated in terms of ultrahigh vacuum (UHV), 1 Torr N2 and helium (He) gas annealing with controlled oxygen partial pressure (PO2) at 920. Comparison of 2 nm and 20 nm ZrO2 films under UHV annealing revealed that the trigger of silicidation is the contact of ZrO2, SiO and Si accompanying disappearance of interfacial SiO2 layer due to SiO desorption. In the contact position, a small amount of SiO gas can easily change ZrO2 to ZrSi2. This reaction model is also applicable to the silicidation of HfO2 and ZrSiO4, at not only stacked high-κ film/Si substrate interface, but also at gate poly-Si/high-κ film interface. Moreover, comparison of UHV, N2 and He annealing with controlled PO2 revealed that the optimal PO2 ranges in He at which the thermal stability of layered structure can be achieved are wider than those in UHV and N2. This result suggests that He gas physically may obstruct SiO creation due to the quenching of atomic vibration at degradation-prone sites in the SiO2 /Si interface, thus reducing probability of bond breaking process, which is the first step of silicidation.

In face recognition, simple classifiers are frequently used. For a robust system, it is common to construct a multi-class classifier by combining the outputs of several binary classifiers; this is called output coding method. The two basic output coding methods for this purpose are known as OnePerClass (OPC) and PairWise Coupling (PWC). The performance of output coding methods depends on accuracy of base dichotomizers. Support Vector Machine (SVM) is suitable for this purpose. In this paper, we review output coding methods and introduce a new sequential fusion method using SVM as a base classifier based on OPC and PWC according to their properties. In the experiments, we compare our proposed method with others. The experimental results show that our proposed method can improve the performance significantly on the real dataset.

A new approach for electronic sealed-bid auctions that preserve the privacy of losing bids is presented. It reduces the number of operations performed by the auctioneers to O(log ); previous protocols require O(N ) or O(N log ) where the number of bidders is N and that of available bidding prices is . Namely, the number of auctioneers' operations in our auction protocol is independent of the number of bidders. This feature offers strong advantages in massive auctions. We also propose a new scheme that checks the equality of two values without disclosing them. The scheme enhances our basic auction protocol, in terms of security and communication costs.

This paper presents a new method for embedding digital watermarks into Bezier polynomial patches. An object surface is supposed to be represented by multiple piecewise Bezier polynomial patches. A Bezier patch passes through its four-corner control points, which are called data points, and does not pass through the other control points. To embed a watermark, a Bezier patch is divided into two patches. Since each subdivided patch shares two data points of the original patch, the subdivision apparently generates two additional data points on the boundaries of the original patch. We can generate the new data points in any position on the boundaries by changing the subdivision parameters. The additional data points can not be removed without knowing some parameters for subdividing and deforming the patch, hence the patch subdivision enables us to embed a watermark into the surface.

This paper presents a novel wavelet compression technique to increase compression of images. Based on zerotree entropy coding method, this technique initially uses only two symbols (significant and zerotree) to compress image data for each level. Additionally, sign bit is used for newly significant coefficients to indicate them being positive or negative. Contrary to isolated zero symbols used in conventional zerotree algorithms, the proposed algorithm changes them to significant coefficients and saves its location, they are then treated just like other significant coefficients. This is done to decrease number of symbols and hence, decrease number of bits to represent the symbols used. In the end, algorithm indicates isolated zero coordinates that are used to change the value back to original during reconstruction. Noticeably high compression ratio is achieved for most of the images, without changing image quality.

Kernel methods such as the support vector machines map input vectors into a high-dimensional feature space and linearly separate them there. The dimensionality of the feature space depends on a kernel function and is sometimes of an infinite dimension. The Gauss kernel is such an example. We discuss the effective dimension of the feature space with the Gauss kernel and show that it can be approximated to a sum of polynomial kernels and that its dimensionality is determined by the boundedness of the input space by considering the Taylor expansion of the kernel Gram matrix.

We propose a simple method for the chromatic dispersion measurement of optical fibers by using bi-directional modulation of a Mach-Zehnder electro-optical modulator embodied in a fiber loop mirror. The detected output of the bi-directionally modulated light, with time difference, creates fading in the RF domain. Dispersion is found by measuring the period of fading at different wavelengths.

Goldwasser and Sipser proved that every interactive proof system can be transformed into a public-coin one (a.k.a. an Arthur-Merlin game). Unfortunately, the applicability of their transformation to cryptography is limited because it does not preserve the computational complexity of the prover's strategy. Vadhan showed that this deficiency is inherent by constructing a promise problem Π with a private-coin interactive proof that cannot be transformed into an Arthur-Merlin game such that the new prover can be implemented in polynomial-time with oracle access to the original prover. However, the transformation formulated by Vadhan has a restriction, i.e., it does not allow the new prover and verifier to look at common input. This restriction is essential for the proof of Vadhan's negative result. This paper considers an unrestricted transformation where both the new prover and verifier are allowed to access and analyze common input. We show that an analogous negative result holds even in this unrestricted case under a non-standard computational assumption.

IEEE 802.11 standard and the enhanced amendments have defined several transmission rates for mobile stations to transmit and receive data frames. With the characteristic of modulation schemes, a higher network throughput can be expected by using higher level modulation scheme, but frame error probability will also become higher. Doubtlessly, it is an open issue of selecting a proper modulation scheme for a pair of mobile stations in time-varying indoor environment. This paper proposes a safe multiple access-rates transmission (SMART) scheme to enhance the reliability of data transmission in IEEE 802.11 multi-rate infrastructure wireless networks. SMART scheme provides reliable transmission by reserving a retransmission period which immediately follows the transmitted frame and is estimated by a lower transmission rate according to the transmitted frame. The performance of SMART scheme is evaluated by analytical model and simulation experiment, which show that the proposed scheme is significantly better than the IEEE 802.11 standard under the real environment with asymmetric traffic load. An enhanced SMART (ESMART) scheme is also proposed especially to improve bandwidth waste for long packet length at access point (AP). The performance measurements, such as goodput, throughput, average access delay, and service rate, are obtained and compared for the different schemes.

This paper describes feasibility of a proposed fixed wireless access system with CDMA technology. The system adopts a primary modulation of 16 QAM and the same frequency allocation in all cells to improve spectral efficiency. The system capacity is 1 Gbps per cell within 120 MHz bandwidth. The number of available orthogonal codes corresponds to the orthogonal code length in the system. All subscribers can attain an error free condition with output power control in the presence of inter-cell interference. The following two items are considered to examine the proposed system feasibility. 1) A test modem is fabricated, and a back-to-back modem BER performance is measured. An inter-symbol interference (ISI) level of the modem is estimated with the measured performance. 2) A computer simulation of down-link power control is carried out considering inter-cell interference and impairment factors of the power control such as intra-sector interference caused by the ISI and limited ranges of total and relative output power controls. The simulation results show that the proposed system would be feasible because the obtained power penalties caused by the above impairment factors are negligible.

This paper deals with a first evaluation of the efficiency and the robustness of the real-time "v-disparity" algorithm in stereovision for generic road obstacles detection towards various types of obstacles (vehicle, pedestrian, motorbike, cyclist, boxes) and under adverse conditions (day, night, rain, glowing effect, noise and false matches in the disparity map). The theoretical good properties of the "v-disparity" algorithm--accuracy, robustness, computational speed--are experimentally confirmed. The good results obtained allow us to use this stereo algorithm as the onboard perception process for Driving Safety Assistance: conductor warning and longitudinal control of a low speed automated vehicle (using a second order sliding mode control) in difficult and original situations, at frame rate using no special hardware. Results of experiments--Vehicle following at low speed, Stop'n'Go, Stop on Obstacle (pedestrian, fallen motorbike, load dropping obstacle)--are presented.

A new bipolar scan waveform is proposed to increase the light emission duty factor by achieving the fast address in AC plasma display panel (AC-PDP). The new bipolar scan waveform consists of two-step scan pulse, which can separate the address discharge mode into two different discharge modes: a space charge generation mode and a wall charge accumulation mode. By adopting the new bipolar scan waveform, the light emission duty factor is increased considerably under the single scan ADS driving scheme due to the reduction of address time per single subfield.

This paper presents new results in the field of very low bitrate coding and compression using 3D informations. Contrary to prior art in model-based coding where 3D models have to be known, the 3D models are automatically computed from the original video sequence. The camera parameters and the scene content are supposed unknown and the video sequence is processed on the fly. A stream of 3D models is then extracted and compressed, using adapted compression techniques. We finally show the results of the proposed compression scheme, and the efficiency of this approach.

We propose a mathematical model to analyze the performance of TD-CDMA/TDD systems in terms of call blocking probability and then find the optimum time-slot switching-point at the smallest call blocking probability considering asymmetrical traffic load distribution for various kinds of service applications.

In this paper, the method of locating multiple transmission zeros by the tap-coupling technique is described for bandpass filters (BPFs), using short-ended λ/2 resonators and its application to a duplexer. First, the method of locating the transmission zero using the short-ended λ/2 resonators is examined with various excitation methods. We focus on four types of short-ended λ/2 resonators: the end-coupling type, tap-coupling type, capacitive tap-coupling type and inductive tap-coupling type. Secondly, the BPFs based on the basic characteristics of the respective resonators are proposed and designed on the basis of a general filter theory with narrow band approximation. Lastly, we propose and design new duplexers consisting of the proposed BPFs. The results lead to the conclusion that the basic characteristics of the short-ended λ/2 resonators are useful for realizing a BPF with multiple transmission zeros and a high-performance duplexer fabricated without increasing the number of elements.

In this paper, as an important technology for the software-defined radio, a novel scheme of adaptive array antenna utilizing bandpass sampling technique is proposed. For adaptive signal processing, it is necessary to convert the radio frequency signal received by the antenna that is given by real number into baseband region, i.e., complex number region. Then, the method for dividing the bandpass sampled signal to in-phase and quadrature components is analyzed. The sampling scheme is called the IQ-division bandpass sampling. An adaptive array antenna based on the IQ-division bandpass sampling is characterized by the signal processing at the bandpass sampled signal stage, namely, intermediate frequency stage, not baseband. Finally, we will confirm the validity of the proposed scheme through an experiment in a radio anechoic chamber.

A negative thermal expansion ceramic substrate and an athermal fiber Bragg grating component with the substrate were subjected to reliability tests. We confirmed that the component has adequate durability for use as optical filters in the WDM system, under test conditions of damp heat, low temperature, mechanical shock and vibration. (50 words)

In a content-based image retrieval (CBIR) system, both the retrieval relevance and the response time are very important. This letter presents the condensed two-stage search method as a new fast image retrieval approach by making use of the property of Cauchy-Schwarz inequality. The method successfully reduces the overall processing time for similarity computation, while maintaining the same retrieval relevance as the conventional exhaustive search method. By the extensive computer simulations, we observe that the condensed two-stage search method is more effective as the number of images and dimensions of the feature space increase.