We present two new parallel algorithms for extending the domain of a UOWHF. The first algorithm is complete binary tree based construction and has less key length expansion than Sarkar's construction which is the previously best known complete binary tree based construction. But only disadvantage is that here we need more key length expansion than that of Shoup's sequential algorithm. But it is not too large as in all practical situations we need just two more masks than Shoup's. Our second algorithm is based on non-complete l-ary tree and has the same optimal key length expansion as Shoup's which has the most efficient key length expansion known so far. Using the recent result, we can also prove that the key length expansion of this algorithm and Shoup's sequential algorithm are the minimum possible for any algorithms in a large class of "natural" domain extending algorithms. But its parallelizability performance is less efficient than complete tree based constructions. However if l is getting larger, then the parallelizability of the construction is also getting near to that of complete tree based constructions. We also give a sufficient condition for valid domain extension in sequential domain extension.

A low-loss serial power combiner using suspended stripline is described. It consists of novel broadside-coupled directional couplers which have shunt capacitances at the edges of the coupled sections. These additional shunt capacitances compensate for poor directivities of the couplers because of inhomogeneous dielectric in suspended stripline structure. The fabricated three-way power combiner has achieved good performance with insertion loss less than 0.23 dB over a bandwidth of 10% in 2 GHz band.

A mode transformer between the NRD guide and the vertical strip line was developed and applied to the right angle corner, T-junction, and 3-port junction at 60 GHz. Emphasis was placed on a fully CAD-based design procedure by using an electromagnetic field simulator. Agreement between the simulated and measured performances of the junction circuit was obtained, and thus the validity of the design procedure was confirmed. A well-balanced transmission coefficient of the 3-port junction, found to be 4 0.5 dB, was observed in the bandwidth of 2 GHz around a center frequency of 60 GHz.

Nonlinear distortions in an anti-series varactor pair (ASVP) are analyzed by a perturbation method. To the authors' knowledge, this paper presents the first derivation of an analytical expression that explicitly shows intermodulation and harmonic distortions of the ASVP. In addition to canceling the expected even-order distortion, the third-order distortion can be suppressed simultaneously when a certain condition is satisfied. We also find that the second- and third-order distortions can be greatly suppressed without dependence on dc bias voltage if the varactors in the ASVP have an ideal abrupt p-n junction. These theoretical predictions are verified by measuring the second- and third-order harmonic distortions of an ASVP. The experimental results show that the second-order harmonic distortion is suppressed by approximately 20 dB. The third-order harmonic distortion is suppressed to the same extent in the theoretically predicted dc bias voltage range.

In this work we give an extension of Kauffman's NK-Landscapes to multiobjective MNK-Landscapes in order to study the effects of epistasis on the performance of multiobjective evolutionary algorithms (MOEAs). This paper focuses on the development of multiobjective random one-bit climbers (moRBCs). We incrementally build several moRBCs and analyze basic working principles of state of the art MOEAs on landscapes of increased epistatic complexity and number of objectives. We specially study the effects of Pareto dominance, non-dominance, and the use of memory and a population to influence the search. We choose an elitist non-dominated sorting multiobjective genetic algorithm (NSGA-II) as a representative of the latest generation of MOEAs and include its results for comparison. We detail the behavior of the climbers and show that population based moRBCs outperform NSGA-II for all values of M and K.

This paper presents a novel ZVS bidirectional 1 kW class DC-DC converter used for a photovoltaic (PV) system. The proposed circuit is based on a boost&buckboost converter, which consists of a boost converter and a buckboost converter. Bidirectional soft switching is realized by using of coupled inductors and auxiliary switches in the circuit. From the analysis of the circuit operation, ZVS conditions of the switches are derived. In the experiment, the maximum efficiency of the proposed converter during forward power flow was 97.1% on output power of 320 W.

A look-up table (LUT) cascade is a new type of a programmable logic device (PLD) that provides an alternative way to realize multiple-output functions. An LUT ring is an emulator for an LUT cascade. Compared with an LUT cascade, the LUT ring is more flexible. In this paper we discuss the realization of multiple-output functions with the LUT ring. Unlike an FPGA realization of a logic function, accurate prediction of the delay time is easy in an LUT ring realization. A prototype of an LUT ring has been custom-designed with 0.35 µm CMOS technology. Simulation results show that the LUT ring is 80 to 241 times faster than software programs on an SH-1, and 36 to 93 times faster than software programs on a PentiumIII when the frequencies for the LUT ring and the MPUs are the same, but is slightly slower than commercial FPGAs.

New Recommendation and Future Standards highlight the Power Factor Correction (PFC) converter as a basic requirement for switching power supplies. Most high-frequency power factor correctors use resistor emulation to achieve a near-unity power factor and a small line current distortion. This technique requires forcing the input current with an average-current-mode control to follow the input voltage. Stability of this system was discussed previously by using some linear models. However, in this paper, two nonlinear phenomena have been encountered in the PFC circuit, period doubling bifurcation and chaos. Detection of these new instability phenomena in the stable regions predicted by the prior linear PFC models makes us more susceptible towards them, and reveals the need to consider a nonlinear models. A nonlinear model performing the practical operation of a boost PFC converter has been developed. Then, a simplified and accurate nonlinear model has been proposed and verified experimentally. As a result from this model, instability maps have been introduced to determine the boundary between stable and unstable operating ranges. Then, the period doubling bifurcation has been studied through a new proposed technique based on the capacitor storage energy. It is cleared that, As the load lessens, a required extra storage power is needed to achieve the significant increase in the output voltage. Then, if the PFC system can provide this extra energy, the operation can reach stability with new zero-storage energy else the system will have double-line zero energy that is period doubling bifurcation.

Since the TCP is the transport protocol for most Internet applications, evaluation of TCP throughput is important. In this paper, we establish a framework of evaluating TCP throughput by simple measurement. TCP throughput is generally measured by sending TCP traffic and monitoring its arrival or using data from captured packets, neither of which suits our proposal because of heavy loads and lack of scalability. While there has been much research into the analytical modeling of TCP behavior, this has not been concerned with the relationship between modeling and measurement. We thus propose a lightweight method for the evaluation of TCP throughput by associating measurement with TCP modeling. Our proposal is free from the defects of conventional methods, since measurement is performed to obtain the input parameters required to calculate TCP throughput. Numerical examples show the proposed framework's effectiveness.

The problem of signal restoration in the presence of observation space noise has been tackled extensively. However, restoration of degraded signals in the presence of signal space noise leads to considerable complexity because it becomes difficult to distinguish between the original signal and the noise. In this paper, a partial projection filter has been devised for the restoration of signals degraded by both the signal space and the observation space noises. A closed form of the proposed filter has been derived and its performance has been verified experimentally.

This paper introduces an efficient affine projection algorithm (APA) using iterative hyperplane projection. The inherent effectiveness against the rank deficient problem has led APA to be the preferred algorithm to be employed for various applications over other variety of fast converging adaptation algorithms. However, the amount of complexity of the conventional APA could not be negligible because of the accomplishment of sample matrix inversion (SMI). Another issue is that the "shifting invariance property," which is typically exploited for single channel case, does not hold ground for space-time decision-directed equalizer (STDE) application deployed in single-input-multi-output (SIMO) systems. Therefore, fast adaptation schemes, such as fast traversal filter based APA (FTF-APA), becomes impossible to utilize. The motivation of this paper deliberates on finding an effective algorithm on the basis of APA, which yields low complexity while sustaining fast convergence as well as excellent tracking ability. The performance of the proposed method is evaluated under wireless SIMO channel in respect to bit error rate (BER) behavior and computational complexity, and upon completion, the validity is confirmed. The performance of the proposed method is evaluated under wireless SIMO channel in respect to bit error rate (BER) behavior and computational complexity, and upon completion, the validity is confirmed.

The notion of effective bandwidth provides an elegant and powerful mathematical basis for the provision of QoS-assured services over IP networks. In this paper, we propose a semi-parametric estimator of effective bandwidth, called Gaussian estimator using buffer masurement, for superposition of sources in IP networks. In contrast to most existing proposals concerning the effective bandwidth estimator, our proposal works based on a small set of measurements of the workload in the buffer of a router. We analytically show the property of the proposed estimator with respect to the dependence on the service rate. We provide numerical results to show that our proposed estimator is more accurate than estimators that rely only on the amount of traffic from sources.

This paper proposes an independent control for parallel-connected multiple uninterruptible power supply (UPS) systems based upon a very simple control scheme. Here, the amplitude and phase angle of the output voltage are the controllable variables. With the only measurement of the output current, the active and reactive components are calculated to define the control variables. The entire system including the equations for the circuit, control and voltage limiters is well represented by a small-signal model, in which the computation of its eigenvalues constitutes the stability proof of the system. The root locus diagram gives an overall panorama of the system performance as a function of a certain gain and it aims to aid the further understanding and the design of the control. The experimental verification is carried out using a mere proportional-integral control scheme, which is a special case of the general control equation used in the theoretical analysis. For some situations, experiments show a flow of lateral current between UPS's, which causes an unbalanced current distribution. By increasing the proportional gain of the control equation for the output voltage amplitude, the lateral current can be substantially suppressed with a consequent improvement of the load sharing. Experimental results under various conditions show excellent results in terms of synchronization, load sharing and stability for three distinct output rating UPS's connected in parallel.

The orthogonal function approach is developed in this paper to solve the Takagi-Sugeno (TS) fuzzy-model-based dynamic equations. The new method simplifies the procedure of solving the TS-fuzzy-model-based dynamic equations into the successive solution of a system of recursive formulae only involving matrix algebra. Based on the presented recursive formulae, an algorithm only involving straightforward algebraic computation is also proposed in this paper. The computational complexity can therefore be reduced remarkably. An illustrated example shows that the proposed method based on the orthogonal functions can obtain satisfactory results.

This paper presents a novel current driving method for the synchronous rectifier (SR) in a Flyback topology. Compared to the previous proposed Current Driven Synchronous Rectifier (CDSR), the proposed CDSR features simple structure, low power loss and good performance. The proposed SR driving method is implemented in a 64 W Flyback converter with universal input, and efficiency as high as 92.5% is achieved at low input (90 V ac) and full load condition.

The design, manufacture, and test results are presented for a 90polarization-rotating Van Atta array reflector with suppressed scattered field for the 1.27-GHz band. The reflector consists of 48 element antennas, half for horizontal polarization and half for vertical polarization. It receives a horizontally or vertically polarized wave and retransmits a vertically or horizontally polarized wave, respectively. The measured cross-polarized radar cross section of the reflector was 15.8 dBm2 on average, which agreed well with a theoretical prediction. Although the suppression of the scattered field was limited to about -20 dB relative to the retransmitted field, we could suppress more the scattered field by accurate positioning and careful characteristics adjustment of element antennas. Theoretical calculations showed that total phase errors of the element antennas including positioning errors and impedance characteristics errors have to be within 7.5to suppress the scattered field by less than -30 dB.

In IP-based mobile networks, a few of mobility agents (e.g., home agent, foreign agent, etc.) are used for mobility management. Recently, Hierarchical Mobile IPv6 (HMIPv6) was proposed to reduce signaling overhead and handoff latency occurred in Mobile IPv6. In HMIPv6, a new mobility agent, called mobility anchor point (MAP), is deployed in order to handle binding update procedures locally. However, the MAP can be a single point of performance bottleneck when there are a lot of mobile node (MNs) performing frequent local movements. This is because the MAP takes binding update procedures as well as data packet tunneling. Therefore, it is required to control the number of MNs serviced by a single MAP. In this paper, we propose a load control scheme at the MAP utilizing an admission control algorithm. We name the proposed load control scheme proactive load control scheme to distinct from the existing load control schemes in cellular networks. In terms of admission control, we use the cutoff priority scheme. We develop Markov chain models for the proactive load control scheme and evaluate the ongoing MN dropping and the new MN blocking probabilities. As a result, the proactive load control scheme can reduce the ongoing MN dropping probability while keeping the new MN blocking probability to a reasonable level.

In this paper, a novel type of the step-up high frequency transformer linked full-bridge soft-switching phase-shift PWM DC-DC power converter with ZVS and ZCS bridge legs is proposed for small scale fuel cell power generation systems, automotive AC power supplies. A tapped inductor filter with a freewheeling diode is implemented in the proposed soft-switching DC-DC power converter to minimize the circulating current in the high-frequency step-up transformer primary side and high-frequency inverter stage. Using a tapped inductor filter with a freewheeling diode makes possible to reduce the circulating current without any active switches and theirs gate-drive circuits. The operating principle of the proposed DC-DC power converter with each operation mode during a half cycle of the steady state operation is explained. The optimum design of the tapped inductor turns ratio is described on the basis of the circuit simulation results. Developing 1 kW 100 kHz prototype with power MOSFETs and 36 V DC source verifies the practical effectiveness of the proposed soft-switching DC-DC power converter. The actual efficiency of the proposed DC-DC power converter is obtained 94% for the wide load and output voltage variation ranges.

Iterative multiuser detection and space-time coding are two promising techniques to increase the capacity and performance of coded multiuser systems in wireless channels. In this paper, a low-complexity iterative multiuser receiver is proposed using combined group multiuser detection and interference cancellation for space-time block coded MC-CDMA system. Turbo code is used for outer channel coding with log-MAP decoding. In each group, consisting of smaller number of users, multiuser likelihood ratios can be computed by employing MAP-based approach by taking into account of all possible transmitted symbols within each STBC time slot for these users. Moreover, once decoding information of all users are available after the first iteration, soft interference cancellation can be used instead of groupwise MAP-based detection for lower complexity, without sacrificing the performance significantly. Simulation results are presented in a Rayleigh multipath fading environment. The proposed receiver offers performance very close to that of single user system within a few iterations of joint detection and decoding.

Leakage power is predicted to become dominant in the total operation power as the transistor technology gets advanced. Even in the current technology, dramatic increase of leakage power at elevated temperature is a big problem. Burn-in testing, which is typically performed at 125, is facing at difficulties such as throughput degradation or thermal runaway due to increase of leakage power. Reducing leakage power at operation time is essential to solve these problems. We propose a novel approach to make use of an enable signal of a gated-clock technique for reducing active leakage power. A sleep transistor is provided between combinational logic circuits and the ground, and is controlled by the enable signal. When state transitions do not occur in Finite-State-Machines (FSM's), the enable signal becomes low and the state flip-flops keep the data. At the same time, the sleep transistor is turned off so that combinational logic gates are electrically disconnected from the ground to reduce leakage. Simulation results have shown that the proposed scheme reduces active leakage power by 30-60% in 0.18 µm technology. The total power was reduced by 20% at the maximum at 125. It was also found that performance degradation was tolerable for burn-in testing.