The knowledge of a good enclosure of the range of a function over small interval regions allows us to avoid convergence of optimization algorithms to a non-global point(s). We used interval slopes f[X,x] to check for monotonicity and integrated their derivative forms g[X,x], x X by quadratic and Newton methods to obtain narrow enclosures. In order to include boundary points in the search for the optimum point(s), we expanded the initial box by a small width on each dimension. These procedures resulted in an improvement in the algorithm proposed by Hansen.

Aging is progressing in our country. Cerebral disease poses a serious problem. Viewing this problem objectively, we can say that support of aging and cerebral disease patients is a useful research theme. To the present, we have done rank evaluation of cerebral disease using synthetic face picture images. This study assesses cognitive ability and expression control ability for intoxication, which is known to impair thinking, cognition, and memory ability. We also examine correspondence of intoxication to cerebral disease. Measurement of cognitive ability corresponds to observation of an internal condition; the measurement of expression control ability corresponds to observation of an external condition. In measurement of cognitive ability, we simulated early stage symptoms of vascular dementia in the second stage of BAC. Also, decreased cognitive ability occurs from the first stage of BAC on face recognition to figure and language. Moreover, face test results show significant difference between decrease in the first stage of BAC and one in the second stage of BAC. These results indicate the possibility of rank evaluation and early stage detection of vascular dementia using a face picture image. From measurement of expression control ability, we obtained the result that we can judge whether a subject has reached second stage of BAC by observing an expression's strength of smile. The second stage of BAC shows symptoms similar to those of vascular dementia. We found the possibility that smile is valid as one externally-observable index for detection of cerebral disease.

In this paper, a novel 622 Mb/s burst-mode clock and data recovery (CDR) circuits with muxed oscillators are realized for passive optical network (PON) application. The CDR circuits are implemented with 0.35 µm CMOS process technology. Lock is accomplished on the first data transition and data are sampled at the optimal point. The experimental results show that the proposed CDR circuits recover the incoming 400-622 Mb/s burst mode input data without errors.

RF diamond FETs have been realized on a hydrogen-terminated diamond surface conductive layer. By utilizing the self-aligned gate fabrication process which is effective for the reduction of the parasitic resistance, the transconductance of diamond FETs has been greatly improved. Consequently, the high frequency operation of 22 GHz has been realized in 0.2 µ m gate diamond MISFETs with a CaF2 gate insulator. This value is the highest in diamond FETs and is comparable to the maximum value of SiC MESFETs at present.

In this paper, we proposed the doubly tapered electromagnetic periodic structure (DT-EPS) bandstop filters in coplanar waveguide (CPW) and cylindrical coplanar waveguide (CCPW). The DT-EPS bandstop filter not only can effectively improve the stopband rejection but also increase its bandwidth. In addition, this technique can significantly reduce the passband ripples compared with conventional case.

DC and RF performances of AlGaN/GaN HEMTs are simulated using a two-dimensional device simulator with the material parameters of GaN and AlGaN. The cut-off frequency is estimated as 205 GHz at the gate length of 0.05 µm and the drain breakdown voltage at this gate length is over 10 V. The values are satisfactory for millimeter wavelength power applications. The use of thin AlGaN layers has key importance to alleviate gate parasitic capacitance effects at this gate length.

As head-disk spacing is reduced, the effects caused by inter-molecular level interactions between head-slider and disk media are becoming a severe stability concern of head-slider's positioning in both flying height and track following directions. Therefore, there is a need to explore simple but effective methods for characterizing two dimensional (2D) stability. Ideally methods should be easy to implement in both the laboratory and in the quality control of disk drive and component manufacturing. A reading process based in-situ method is explored in this work. The method is simple and can effectively reveal the 2D stability of the head-slider in both laboratory and manufacturing environments. The results obtained also suggest that the observable sway mode vibration of the suspension can be excited earlier than the air-bearing vibration mode, when the flying height is reduced.

Brain subsystems have a high degree of information processing ability using nonlinear dynamics and although various neuron models and artificial neural networks have been investigated, the information processing functions of biological neural networks have not yet been clarified. Recently, various research efforts have confirmed that dendrites perform an important role in brain information processing. In this paper, we discuss the nonlinear characteristics of a hardware active dendrite model, in order to clarify information encoding and transmission via action potentials. That is to say, we show that our proposed model can reproduce the nonlinear characteristics of a biologically active dendrite. First, the hardware active dendrite model we propose is described. We next discuss the response characteristics for pulse stimuli using the model. As a result, when input pulses are applied to an active line, which is the basic structure of the dendrite model, it is shown clearly that backpropagation characteristics are acquired and that the characteristics are qualitatively in agreement with the characteristics of biological dendrites. Furthermore, we verify that the ratio of input to output frequency at the cell body is influenced by the backpropagation characteristics with two branches, which is the simplest structure in the active dendrite model. Thus, with backpropagation characteristics, the possibility that the model can carry out clearly the information processing of biological neural networks, is suggested.

NK-Landscapes are stochastically generated fitness functions on bit strings, parameterized with N bits and K epistatic interactions between bits. The term epistasis describes nonlinearities in fitness functions due to changes in the values of interacting bits. Empirical studies have shown that the overall performance of random bit climbers on NK-Landscapes is superior to the performance of some simple and enhanced genetic algorithms (GAs). Analytical studies have also lead to suggest that NK-Landscapes may not be appropriate for testing the performance of GAs. In this work we study the effect of selection, drift, mutation, and recombination on NK-Landscapes for N = 96. We take a model of generational parallel varying mutation GA (GA-SRM) and switch on and off its major components to emphasize each of the four processes mentioned above. We observe that using an appropriate selection pressure and postponing drift make GAs quite robust on NK-Landscapes; different to previous studies, even simple GAs with these two features perform better than a random bit climber (RBC+) for a broad range of classes of problems (K 4). We also observe that the interaction of parallel varying mutation with crossover improves further the reliability of the GA, especially for 12 < K < 32. Contrary to intuition, we find that for small K a mutation only evolutionary algorithm (EA) is very effective and crossover may be omitted; but the relative importance of crossover interacting with varying mutation increases with K performing better than mutation alone (K > 12). This work indicates that NK-Landscapes are useful for testing each one of the major processes involved in a GA and for assessing the overall behavior of a GA on complex non-linear problems. This study also gives valuable guidance to practitioners applying GAs to real world problems of how to configure the GA to achieve better results as the non-linearity and complexity of the problem increases.

A millimeter-wave radio access system has a number of features that makes it appealing as one approach to broadband communications. However, for a millimeter-wave system to come into wide use, it must be miniaturized and the associated costs reduced. We have succeeded in realizing a compact 156 Mbps radio transceiver with a 38 GHz band optimizing RF architecture. We also adopted newly developed three-dimensional laminated MCMs using low cost plastic composite materials. It was confirmed in the initial experiments that this millimeter-wave wireless LAN equipment can cover a sufficient service area for broadband telecommunications in an indoor environment.

It is known that Viterbi decoding based on the code trellis and syndrome decoding based on the syndrome trellis (i.e., error trellis) are equivalent. In this paper, we show that Scarce State Transition (SST) Viterbi decoding of convolutional codes is equivalent to syndrome decoding. First, we derive fundamental relations between the hard-decision input to the main decoder and the encoded data for the main decoder. Then using these relations, we show that the code trellis module for the main decoder in an SST Viterbi decoder can be reduced to a syndrome trellis module. This fact shows that SST Viterbi decoding based on the code trellis is equivalent to syndrome decoding based on the syndrome trellis. We also calculate the SST Viterbi decoding metrics for general convolutional codes assuming an AWGN channel model. It is shown that the derived metrics are equal to those of conventional Viterbi decoding. This fact shows that SST Viterbi decoding is equivalent to conventional Viterbi decoding, and consequently to syndrome decoding.

Adaptive arrays have been recognized as an attractive mean for overcoming multipath fading and interference rejection in the field of mobile communications. In, an adaptive array applicable to single-user spread spectrum (SS) systems has been proposed. In this system, any a priori information concerning incoming signal, even the spreading code and synchronization, is not necessary while it achieves equalizing, beamforming and despreading of a received signal, simultaneously. In this paper, we propose a multistage blind adaptive array antenna based on the above-mentioned adaptive algorithm in order to realize blind signal processing that is applicable to multi-user SS systems. Behavior and performance of the proposed multistage system are examined through computer simulations.

We report in this paper, the performance of AlGaN/GaN HFETs in the context of high power, low noise and high temperature operations, along with a comparison of their characteristics with other conventional technologies. Finally, a single stage modulator driver for long haul optical communications is presented as an example of application of the GaN-based devices high power handling capabilities.

It is very difficult to simultaneously achieve power and cost reductions in address-driver circuits of a plasma-display panel (PDP) unit in which an energy-recovery scheme utilizing the resonance of a series-connected inductor and electrode parasitic capacitors is used. This is because an increase in parasitic capacitance and high-speed circuit operation become necessary as the display panel becomes larger in size and higher in resolution. In particular, low-power operation of address-driver ICs is key to avoiding the installation of heat sinks on the ICs. We propose herein new power-dispersion methods that can greatly reduce the power dissipation of address-driver ICs even when large parasitic capacitance is driven at high speed. The proposed methods enable a reduction in the power dissipation of address-driver ICs without deteriorating the operational speed by dispersing their powers into external resistors, and by supplying power to address-driver ICs in two voltage steps during both rising and falling time intervals when the address changes. Our results indicate that the power dissipation of address-driver ICs and the total cost of the address drive unit of a plasma-display panel can be reduced to 29% and 53%, respectively, compared with those of the ICs and the unit that are driven by the conventional address-driving method.

A new current-mode quadrature oscillator circuit using two differential voltage current conveyors (DVCCs), two grounded capacitors and two grounded resistors is presented. Two high output impedance sinusoid current sources with 90phase difference are available in the proposed circuit. The oscillation condition and oscillation frequency are orthogonally controllable. The use of only grounded capacitors and resistors makes the proposed circuit ideal for integrated circuit implementation. Simulation results are also included.

A technique for the design of circular- and racetrack-shaped NRD guide ring resonators was developed based on the mode coupling theory. Besides the operating mode, a parasitic mode is generated at curved sections of the resonator as a result of the mode conversion. Resonance of the NRD guide ring resonator is derived by characteristic equations of the coupled modes and then employed in making the design diagrams, which are useful for determining the dimensions of the ring resonators. It is shown that the discrepancy between the experimental results and previous theory can be resolved by using the present theory. Low loss, small-sized ring resonators with curvature radii of less than 5.3 mm were fabricated at 60 GHz and a band rejection performance of more than 30 dB was observed. Moreover, a procedure for the design of the channel dropping filter was developed and a 2-pole filter, which has great advantages such as a low insertion loss of 1.2 dB and a compact size smaller than that of a golf ball, was successfully developed by using two racetrack-shaped ring resonators.

A low power MPEG-4 video codec LSI with the capability for core profile decoding is presented. A 16-b DSP with a vector pipeline architecture and a 32-b arithmetic unit, eight dedicated hardware engines to accelerate MPEG-4 SP@L1 codec, CP@L1 decoding and post video processing, 20-Mb embedded DRAM, and three peripheral blocks are integrated together on a single chip. MPEG-4 SP@L1 codec, CP@L1 decoding and post video processing are realized with a hybrid architecture consisting of a programmable DSP and dedicated hardware engines at low operating frequency. In order to reduce the power consumption, clock gating technique is fully adopted in each hardware block and embedded DRAM is employed. The chip is implemented using 0.18-µm quad-metal CMOS technology, and its die area is 8.8 mm 8.6 mm. The power consumption is 90 mW at a SP@L1 codec and 110 mW at a CP@L1 decoding.

A new power and bandwidth efficient modulation technique - Superposed Quadrature Quadrature Amplitude Modulation (SQ2AM) - for use in nonlinear satellite channel is presented. SQ2AM technique expands 2-dimensional SQAM signals into 4-dimensional quadrature modulated signals by using orthogonal baseband waveforms and carriers. The power spectrum and BER performance of SQ2AM are analyzed and compared with those of QPSK, SQAM and Q2PSK in a nonlinearly amplified multi-channel environment.

This paper presents the analysis of the impedance characteristics of a sectoral cylindrical cavity-backed axial slot antenna excited by a probe. The integral equations are derived based on boundary conditions of the proposed structure and they are expressed in terms of dyadic Green functions and unknown current densities. The dyadic Green functions are obtained by using the eigenfunction expansion method together with application of scattering superposition techniques. The unknown current densities are solved by the Method of Moments. The input impedance is subsequently determined from the unknown electric current density at the probe. Numerical results of input impedance and return loss are demonstrated as functions of frequency for various parameters such as cavity length, cavity radius ratio, slot location in φ direction, slot length and probe length. Calculated results are validated by the measurements. At the operating frequency, it is found that the result is sufficiently accurate. The results from this study are very useful for the design of a sectoral cylindrical cavity-backed axial slot array antenna excited by a probe with omnidirectional beam radiation.

Sliding contact behavior is important in the mechanism of collecting current. In this study, the effect of ambient gas including an inert gas on surface film formation and on the contact voltage drop was examined, changing the atmosphere from low pressure to atmospheric pressure. Furthermore, the sliding surface state was observed using SEM, EDX and XPS analyzers after the test operation. As a result, at the sliding contact in an inert gaseous environment (nitrogen and argon), it was confirmed that the contact voltage drop tends to increase. However, it was clarified that any chemically generated surface film is difficult to detect in the inert gas environment by qualitative analysis. On the basis of these results, we suggest the existence of physically adsorbed surface film. The relationship between inert gases and sliding contact phenomena is discussed.