The main contribution of this work is to propose energy-efficient randomized initialization protocols for ad-hoc radio networks (ARN, for short). First, we show that if the number n of stations is known beforehand, the single-channel ARN can be initialized by a protocol that terminates, with high probability, in O(n) time slots with no station being awake for more than O(log n) time slots. We then go on to address the case where the number n of stations in the ARN is not known beforehand. We begin by discussing, an elegant protocol that provides a tight approximation of n. Interestingly, this protocol terminates, with high probability, in O((log n)2) time slots and no station has to be awake for more than O(log n) time slots. We use this protocol to design an energy-efficient initialization protocol that terminates, with high probability, in O(n) time slots with no station being awake for more than O(log n) time slots. Finally, we design an energy-efficient initialization protocol for the k-channel ARN that terminates, with high probability, in O(n/k+log n) time slots, with no station being awake for more than O(log n) time slots.

An electronic model of the coronary vessel consisting of resistor, capacitor and Field Effect Transistor (FET) is proposed in order to perform a dynamic simulation of the left coronary circulation and to clarify its mechanisms. Based on this model, an equivalent circuit of the coronary circulation is constructed that is divided into subepicardial and subendocardial layers and consists of segments of artery, arteriole, capillary, venule and vein for both the layers. In this simulation, the observed flow waveform of the left main artery showed dominance of flow in diastole as compared to that in systole. In epicardium, inverse venous flow was observed in early systole. These simulated waveforms are similar to those in real left coronary circulation observed by physiological and clinical researchers. Among all the segments of intramyocardium, only the venules were found to possess a time-varying resistance characteristics. From the results of this study, it is considered that the combination of resistance and capacitance of the vessel acts as an integrator and a differentiator for blood pressure and intramyocardial pressure, respectively and that the effects of integration of blood pressure and differentiation of intramyocardial pressure play a very important role in determining the factors influencing the left coronary circulation.

The radiation emission in far zones from printed circuit boards (PCBs) is obtained by treating lines on PCBs as transmission lines and calculating the far-field emission due to current distribution on lines. In this paper, we present a more precise circuit model, based on TEM assumption, to decompose the total current into differential-mode current and common-mode current. This circuit model is based on transmission line model, but it considers the effect of ground trace. The finite size ground trace can be viewed as an inductive reactance. A knowledge of the net inductance of the ground trace can aid in the analysis and investigation of PCBs emission. We show the derived equations of the modified transmission lines for the geometrics of practical interest. As time-varying current passes through such ground trace, a voltage drop due to the inductance of the trace will act as a source of the common-mode current. Furthermore, charge stored in capacitance between signal and ground traces will cause the current pulses returning to their source. The magnitudes of currents are slightly unequal in the signal and ground traces, which can cause common-mode current to flow. An unbalanced circuit on a PCB constructed with signal and ground trace pairs will radiate as an asymmetric folded-dipole. By antenna theory, the contribution of differential-mode and common-mode currents to radiated emission of PCBs can be calculated. In addition, comparisons between experimental results and calculation results are also given.

A low bit-rate encoding method which yields a good performance in edge reconstruction while achieving a high compression is proposed through MTF function and the spatial anisotropy of human vision. Human visual weighting factors applied to sub-blocks within each subband in wavelet domain are produced by the spatial anisotropic-filter, then a good perceptual performance can be obtained.

In this paper, as a practical application, we focus on the genetic algorithm (GA) for multi-head surface mounting machines which are used to populate printed circuit boards (PCBs). Although there have been numerous studies on the surface mounting machine, studies on the multi-head case are rare because of its complexity. The multi-head surface mounting machine can pick multiple components simultaneously in one pickup operation and this operation can reduce much portion of the assembly time. Hence we try to minimize the assembly time by maximizing the number of simultaneous pickups, resulting in reduction of PCB production cost. This research introduces a partial-link GA method for the single-head case. Then, we apply this method to the multi-head case by regarding a reel-group as one reel and a component-cluster as one component. The results of computer simulation show that our genetic algorithm is greatly superior to the heuristic algorithm that is currently used in industry.

Silicon self-interstitial atom diffusion and implantation induced damage were studied by using molecular dynamics methods. The diffusion coefficient of interstitial silicon was calculated using molecular dynamics method based on the Stillinger-Weber potential. A comparison was made between the calculation method based on the Einstein relationship and the method based on a hopping analysis. For interstitial silicon diffusion, atomic site exchanges to the lattice atoms occur, and thus the total displacement-based calculation underestimates the ideal value of the diffusivity of the interstitial silicon. In addition with calculating the diffusion constant, we also identified its migration pathway and barrier energy in the case of Stillinger-Weber potential. Through a study of molecular dynamics calculation for the arsenic ion implantation process, it was found that the damage self-recovering process depends on the extent of damage. That is, damage caused by a single large impact easily disappears. In contrast, the damage leaves significant defects when two large impacts in succession cause an overlapped damage region.

In high-speed TDMA mobile communications, frequency-selective fading is a serious problem because a delay time difference between multipath signals is large in comparison with symbol duration. We have proposed a spatial-domain RAKE receiver using a multibeam adaptive antenna to reduce frequency-selective fading and to realize path-diversity. The multibeam adaptive antenna resolves multipath signals in the spatial domain, and combines array outputs. In this paper, we propose the application of MUSIC algorithm to estimation of the time delays of multipath signals to make the incident signals coincide with a common reference signal. Because the MUSIC algorithm can estimate the time delays accurately, the BER performance of the proposed scheme is improved. Furthermore, we propose weighting factors which easily realize the maximal-ratio combining.

This letter proposes an initial frame synchronization algorithm for orthogonal frequency division multiplexing (OFDM) systems. Since the proposed scheme utilizes only the cyclic prefix and the phase shift of the demodulated data without the aid of any known signals, it can be applied not only at the beginning of data transmission but also at any instant during transmission. The performance of the proposed algorithm is confirmed by computer simulation for QPSK, 8-PSK, and 16-QAM systems.

Path loss and delay profile characteristics of the 3-GHz band are measured and compared for line-of-sight (LOS) and non-line-of-sight (NLOS) paths in a suburban residential area. For the LOS path, the path loss increases as a function of distance squared; and hence the propagation is considered as the free space propagation. For the NLOS paths, it is found that corner losses occur ranging from 28 to 40 dB, and subsequent losses increase as a function of distance squared, but in case of there are open spaces, spaces between the rows of houses or roads intersecting LOS road, the increase was small. The delay spread for the LOS path increased in proportion to power of the distance; and the exponents ranging from 1.9 to 2.9 is found smaller than in urban areas. The delay spreads for the NLOS paths were several times greater than that for the LOS path, and the rate of delay spread increase with distance was found to be several orders of magnitude greater for NLOS paths than the LOS path.

We propose a new sampling control system on image sensor array. Contrary to the random access pixels, the proposed sensor is able to read out spatially variant sampled pixels at high speed, without inputting pixel address for each access. The sampling positions can be changed dynamically by rewriting the sampling position memory. The proposed sensor has a memory array that stores the sampling positions. It can achieve any spatially varying sampling patterns. A prototype of 64 64 pixels are fabricated under 0.7 µm CMOS precess.

Layer-by-layer sequential adsorption process of polyelectrolytes had conventionally been used for the fabrication of the ultra-thin organic film formed by various polymers with different polarity of charge. In this study, hydrophobic Ruthenium complex monomer (tris (bilyridyl) ruthenium (II) hexafluorophosphate) was micelle-wrapped with an anionic surfactant, sodium dodecylbenzenesulfonate, and was assembled with PAH (poly (allylamine hydrochloride)) which has the opposite charge on ITO substrates. With this method, we succeed in fabricating ultra-thin organic films even when the adsorption material is not polymer but monomer. Moreover it was found that the bilayer thickness of the self-assembled (Ru micelle/PAH) was systematically changed by adjusting the solution pH of each bath. By using this process, EL device was fabricated by depositing the thin film of micelle-wrapping ruthenium complex monomer on ITO and formed Bi electrode on top of the film. Light emission was observed by applying voltage to this device.

In many of machine learning problems, it is essential to use not only the training data, but also a priori knowledge about how the world is constrained. In many cases, such knowledge is given in the forms of constraints on differential data or more specifically partial differential equations (PDEs). Neural networks with capabilities to learn differential data can take advantage of such knowledge and easily incorporate such constraints into the learning of training value data. In this paper, we report a structure, an algorithm, and results of experiments on neural networks learing differential data.

We studied theoretically and experimentally an InGaAs/InAlAs/InP polarization-insensitive multiple quantum well (MQW) electroabsorption (EA) modulator operating over a very wide wavelength range in 1.55 µm wavelength region. One of the simplest possible potential-tailored quantum well, "pre-biased" quantum well (PBQW) is used to achieve wide-wavelength polarization insensitivity. PBQW is basically a rectangular quantum well with a thin barrier inserted near one edge of well. This thin barrier effectively introduces "pre-bias" to a rectangular quantum well and the same amount of Stark shift is achieved for electron-heavy hole and electron-light hole transition energies. By incorporating tensile strain into PBQW, polarization-insensitive modulation is achieved over 60 nm wavelength range, from 1510 nm to 1570 nm. This MQW-EA modulator plays an important role in wavelength division multiplexing (WDM) transmission and switching systems.

In this letter we propose a new mode for block ciphers which uses an unknown random block as feedback. We show that the successful differential/linear cryptanalyses of DES under the mode require at least the complexity of the exhaustive key search. We also present the processing overhead of our scheme compared to that of ECB mode.

We propose a novel adaptive multiple-symbol differential detection (MSDD) scheme that has excellent performance over frequency selective fading (FSF) channels. The adaptive MSDD scheme consists of an adaptive noncoherent least mean square channel estimator that can accomplish channel estimation without any decision delay and the MSDD. The M-algorithm is introduced into this detection scheme to reduce the complication of computation due to increasing observed sequence length in the MSDD. Because of the application of the adaptive channel estimator and the M-algorithm, this adaptive MSDD make it possible that channel estimation is accomplished for every symbol along M surviving paths without any decision delay. And the SER performance of this adaptive MSDD is not affected by phase fluctuation introduced by a channel because the MSDD and the noncoherent channel estimator are applied. The adaptive MSDD scheme is applied to typical constellation of 16APSK, the (4,12) QAM and the star QAM. The excellent tracking performance of this adaptive MSDD scheme over FSF channels is confirmed by computer simulations.

Agent-based simulations are expected to enable analysis of complex social phenomena. In such simulations, one of the important behaviors of the agents is negotiation. Throughout the negotiations, the agents can make complex interactions with each other. Therefore, the ability of agents to perform negotiation is important in simulations of artificial societies. In this paper, we focus on price negotiations, in which the two sides have opposing interests. In the conventional price negotiation model, the process consists of an alternate succession of directly presented offers and counter-offers exchanging the desired prices. As an extended price negotiation model, we introduce virtual words to mimic the negotiation techniques of humans for indirectly presenting the desired price. The process of the proposed negotiation model consists of an alternate succession of offers of desired price and counter-offers of a word. The words represent the degree of the agent's demand. We propose agents with reinforcement learning who can acquire the ability to distinguish words and use them to negotiate. As a result, we will show that the virtual words became meaningful in the process of negotiations between agents whose negotiating strategies are acquired by reinforcement leaning.

The increasing diversity in Internet applications necessitates extended Internet architecture that can differentiate forwarding treatment of different types of flows. Diffserv can be a solution to the problem when it is augmented by several additional components. In this paper we describe various issues and possible directions in augmenting Diffserv. We present our analysis of Diffserv architecture, anticipated developments to augment Diffserv architecture, and potential applications of Diffserv.

The Monte Carlo simulation is applied to fault tree analyses of the sequential failure logic. In order to make the validity of the technique clear, case studies for estimation of the statistically expected numbers of system failures during (0, t] are conducted for two types of systems using the multiple integration method as well as the Monte Carlo simulation. Results from these two methods are compared. This validates the Monte Carlo simulation in solving the sequential failure logic with respectably small deviation rates for those cases.

There are many public key cryptosystems that require random inputs to encrypt messages and their security is always discussed assuming that random objects are ideally generated. Since cryptosystems run on computers, it is quite natural that these random objects are computationally generated. One theoretical solution is the use of pseudorandom generators in the Yao's sense. Informally saying, the pseudorandom generators are polynomial-time algorithms whose outputs are computationally indistinguishable from the uniform distribution. Since if we use the Yao's generators then it takes much more time to generate pseudorandom objects than to encrypt messages in public key cryptosystems, we relax the conditions of pseudorandom generators to fit public key cryptosystems and give a minimal requirement for pseudorandom generators within public key cryptosystems. As an example, we discuss the security of the ElGamal cryptosystem with some well-known generators (e. g. , the linear congruential generator). We also propose a new pseudorandom number generator, for random inputs to the ElGamal cryptosystem, that satisfies the minimal requirement. The newly proposed generator is based on the linear congruential generator. We show some evidence that the ElGamal cryptosystem with the proposed generator is secure.

Bit error rates (BER) for playback of (1,7) code employed in optical disc recording were simulated using an ideal (Gaussian) playback waveform, with playback being performed by PRML (Partial Response Maximum-Likelihood) combining a partial response equalizer and a double clock weighted Viterbi decoder. It was found that best BER occurs for PR(2,3,3,2) +7/10 level Viterbi decoding at a weighted value of w = 0.5 for data consisting of 107 symbols. For a minimum bit length of 0.28 µm, BER of 10-4 and less than 10-6 was obtained for SN ratios of 15.6 dB and 17.7 dB, respectively. And for a minimum bit length of 0.26 µm, BER of 10-4 and less than 10-6 was obtained for SN ratios of 16.7 dB and 18.8 dB, respectively. These results demonstrate the feasibility of a minimum bit length of 0.26 µm in current optical disc recorders.