We present a novel kind of integrate-and-fire circuit (IFC) with two periodic inputs: a pulse-train stimulation input and a base input. We clarify that the system state is quantized by the pulse-train stimulation input. Then the system dynamics is described by a return map with quantized state (Qmap). By changing the shape of the base input, various Qmaps can be obtained. The Qmap exhibits co-existence state of various super-stable periodic orbits, and the IFC outputs one of corresponding super-stable periodic pulse-trains depending on the initial state. For a typical case, we clarify the number of co-existing periodic pulse-trains theoretically for the stimulation frequencies. Constructing a simple test circuit, typical phenomena can be verified in the laboratory.

We report here on the electrical and structural characteristics of InGaP/GaInAsN DHBTs with up to a 50 mV reduction in turn-on voltage relative to standard InGaP/GaAs HBTs. High p-type doping levels ( 3 1019 cm-3) and dc current gain (βmax up to 100) are achieved in GaInAsN base layer structures ranging in base sheet resistance between 250 and 750 Ω/. The separate effects of a base-emitter conduction band spike and base layer energy-gap on turn-on voltage are ascertained by comparing the collector current characteristics of several different GaAs-based bipolar transistors. Photoluminescence measurements are made on the InGaP/GaInAsN DHBTs to confirm the base layer energy gap, and double crystal x-ray diffraction spectrums are used to assess strain levels in the GaInAsN base layer.

This paper presents an O(n2)-time algorithm for constructing two edge-disjoint paths connecting two given pairs of vertices in a given tournament graph. It improves the time complexity of a previously known O(n4)-time algorithm.

In this Letter, an analytic method to calculate the cumulative distribution function (cdf) of the cell sojourn time with various distributions of a mobile velocity (constant, uniform, or Gaussian distribution) is presented. Gaussian pdf and cdf are estimated through curve-fitting. The cdf of the cell sojourn time is calculated through a numerical method. It is shown that the simulated result matches very close to the calculated result.

Metallic pair lines transmitting high-frequency information signals above several tens MHz are often used without being twisted, as flat floor cable installed in buildings, ribbon-type cables installed in computer equipment, and traces in printed circuit boards. However, the conversion characteristics of untwisted unbalanced metallic pair lines connecting unbalanced circuits have not been investigated over a wide range of frequencies in the MHz region. First, we developed a method to estimate effective power conversion factors using a cascade connection of F matrices, where the unbalance in impedance and admittance of each pair line is distributed uniformly along the line. As a result some useful information was obtained about the balance-unbalance conversion characteristics of the effective power which can be used to suppress EMI phenomena in wiring, especially over several decades of high frequencies. Next, we attempted to apply the conversion characteristics of untwisted unbalanced pair lines obtained at frequencies below several MHz to techniques for searching for the return circuits of conductors installed in buildings. It was clarified experimentaly that the depth of the equivalent ground plane can be estimated by comparing the measured conversion values of TV feeder lines installed at the place being tested with reference values measured in advance on a copper plate .

This paper analyzes what structural features of graph problems allow efficient parallel algorithms. We survey some parallel algorithms for typical problems on three kinds of graphs, outerplanar graphs, trapezoid graphs and in-tournament graphs. Our results on the shortest path problem, the longest path problem and the maximum flow problem on outerplanar graphs, the minimum-weight connected dominating set problem and the coloring problem on trapezoid graphs and Hamiltonian path and Hamiltonian cycle problem on in-tournament graphs are adopted as working examples.

In this paper, we consider the Integrate-and-Fire Model (ab. IFM) with two periodic inputs. The IFM outputs a pulse-train which is governed by a one dimensional return map. Using the return map, the relationship between the inputs and the output is clarified: the first input determines the global shape of the return map and the IFM outputs various periodic and chaotic pulse-trains; the second input quantizes the state of the return map and the IFM outputs various periodic pulse-trains. Using a computer aided analysis method, the quantized return map can be analyzed rigorously. Also, some typical phenomena are confirmed in the laboratory.

This paper presents a method of calculating an interval including a bifurcation point. Turning points, simple bifurcation points, symmetry breaking bifurcation points and hysteresis points are calculated with guaranteed accuracy by the extended systems for them and by the Krawczyk-based interval validation method. Taking several examples, the results of validation are also presented.

This paper is concerned with the validation of simple turning points of two-point boundary value problems of nonlinear ordinary differential equations. Usually it is hard to validate approximate solutions of turning points numerically because of it's singularity. In this paper, it is pointed out that applying the infinite dimensional Krawcyzk-based interval validation method to enlarged system, the existence of simple turning points can be verified. Taking an example, the result of validation is also presented.

Future satellite communication systems will be developed at Ka-band (20/30 GHz) owing to the relatively wide frequency allocation and current freedom from terrestrial interference for multimedia services. A serious disadvantage of the Ka-band, however, is the very high atmospheric attenuation in rainy weather. Quasi-synchronous CDMA drastically reduces the effect of self-noise with several interesting features of CDMA for mobile communications such as flexible frequency reuse, the capability of performing soft-handover and a lower sensitivity to interference. This paper evaluates the performance of a quasi-synchronous CDMA return link for a Ka-band geostationary satellite communication system. For a fixed satellite channel whose characteristics depend on weather conditions, the signal envelope and phase for this channel is modeled as Gaussian. The bit error and outage probability, and the detection loss due to imperfect chip timing synchronization is analytically evaluated and the system capacity degradation due to the weather condition is estimated. Two cases of general and worst conditions are evaluated, in which i) rain attenuation ii) nonlinearity of transponder are considered. The two cases consist of the general case in which all users are affected by rainy weather, and the worst case in which only the user of interest, not multiple access interferers, is affected by rain attenuation. The results for the two cases of rainy weather clearly show that quasi-synchronous CDMA eases the power control requirements and has less sensitivity to imperfect power control. When dealing with the impact of the satellite transponder nonlinearity in addition to the rain attenuation, the shift of optimum amplifier operating point is shown so that [Eb/N0]sat, defined as the sum of the Eb/N0 value required to obtain a BER equal to Pb at a given output backoff (OBO) and the value of the OBO itself, tends to decrease, and higher BER impairment is given, since the rain attenuation results in the same effect as the additive input backoff (IBO) at the satellite transponder input. As the BER increases, the optimum [Eb/N0]sat and IBO decrease that result in the shift of optimum operating point.

As a super class of tournament digraphs, Bang-Jensen, Huang and Prisner defined an in-tournament digraph (in-tournament for short) and investigated a number of its nice properties. The in-tournament is a directed graph in which the set of in-neighbors of every vertex induces a tournament digraph. In other words, the presence of arcs (x,z) and (y,z) implies that exactly one of (x,y) or (y,x) exists. In this paper, we propose, for in-tournaments, parallel algorithms for examining the existence of a Hamiltonian path and a Hamiltonian cycle and for constructing them, if they exist.

The basic operation characteristics of an asymmetric turnstile which transfers each electron one by one in one direction is described. A novel single electron counter circuit consisting of the asymmetric turnstiles, a load capacitor and an inverter which counts the number of high inputs is proposed. Monte Carlo circuit simulations reveal that the gate clock time of the counter circuit should be long enough to achieve allowable minimum error rate. The counter circuit implementing asymmetric single electron turnstiles is demonstrated to be applicable to a noise reduction system, a Winner-Take-All circuit and an artificial neuron circuit.

We propose concepts of Paley-Wiener multiresolution analysis and Paley-Wiener wavelet frame based on general, not limited to dyadic, dilations of functions. Such a wavelet frame is an extension both of the Shannon wavelet basis and the Journe-Meyer wavelet basis. A concept of "natural" Paley-Wiener wavelet frame is also proposed to clarify whether a Paley-Wiener wavelet frame can naturally express functions from the point of view of the multiresolution analysis. A method of constructing a natural Paley-Wiener wavelet frame is given. By using this method, illustrative examples of Paley-Wiener wavelet frames with general scales are provided. Finally, we show that functions can be more efficiently expressed by using a Paley-Wiener wavelet frame with general scales.

In this paper, we analyze the individual sojourn delay experienced by cells from each virtual channel (VC) passing through an ATM switch port. Traffic from each VC is described by a four-parameter Markov-Modulated Bernoulli process (MMBP). A switch port is assumed to receive traffic from a group of heterogeneous MMBPs and the queueing behavior is modelled by a H-MMBPs/D/1/ queue. Two service disciplines are considered: FIFO and priority. Closed-form formulas of overall as well as individual sojourn delays for both service disciplines are obtained. Although approximation is inevitable in our analysis, the accuracy is good when compare with computer simulations. As a result we provide an efficient tool to estimate cell delay for each individual VC before it is established. Our result can be applied to network resource decision or control problems such as call admission control and routing.

Fiber physical contact (FPC) is proposed and demonstrated as a new method designed to enable fibers to be connected easily with a small structure while maintaining high optical performance. FPC is performed by mating two bare optical fibers in a micro sleeve and fixing them to a holder while they are buckled. Buckling is a phenomenon whereby a long column is bent by compression along its length. PC connection is realized by the buckling force of the fibers themselves and does not require any springs. Optical fiber buckling is studied both theoretically and experimentally. The buckling force, which is determined by an initial span between the optical fiber holding points, remains constant when the span is changed and is useful as the PC force. The buckling amplitude which is determined by the span reduction must be so small that it does not cause excess radiation loss. A suitable span is about 7 mm. This generates a 0.7 N. The allowed span reduction is 0.1 mm. This results in a buckling amplitude of 0.64 mm which prevents radiation losses of above 0.1 dB for 1.31 µm light. Based on a study of fiber buckling, we demonstrate the optical performance for FPC connection with a 0.126 mm diameter micro sleeve in which optical fibers are mated and with polished fiber end faces. The insertion loss is under 0.3 dB and the average return loss is 50 dB for 1.31 µm light. These values are stable in the 20 to 70 temperature range. We confirm that FPC connection realizes high optical performance with a small simple structure.

A sequence of nonnegative integers s=(S1, s2, , sn) is a score sequence of an r-tournament if, for some positive integer r, ther is a directed graph with vertices v1, v2, , vn such that deg+(vj)=sj and deg-(vj)=r(n-1) -sj for each j=1, 2, , n. The score sequence problem of an r-tournament is: Given some positive integer r and a sequence of nonnegative integers, determine whether it is a score sequence of an r-tournament or not. In this paper, we consider several variations of the score sequence problem of an r-tournament, and give efficient algorithms.

Correspondence problem in road image sequence is discussed and a method to establish road correspondence from its perspective image sequence is suggested. The proposed method is mainly based on the features of turn angles of road edge points, while the turn angle for each edge point at one time can be computed from the frame based on the determination of matching points whin that frame. The turn angles will change from frame to frame according to the panning rotation of the camera and, each stationary edge point, the difference of turn angles between two frames equals the panning angle of the camera. Thus we develop an algorithm to estimate the value of panning angle of the camera by which correspondence in road image sequence can be established.

A new line simulator, SEMALIS has been developed. This simulator can handle complicated lot processings to maintain processing quality and efficient line operations to improve line performance. The current manufacturing line consists of five resource models: lot, process sequence, equipment, lot processing, and line operations. The parameters of these models are defined so as to accurately reflect the state of the line operations. From our simulation results, we confirmed that SEMALIS accurately identifies bottlenecks or starvations where equipment can be added or reduced to optimize equipment utilization through resource planning, and that SEMALIS can also be used to evaluate the long-term effects of line operating methods on the line performance of ASIC manufacturing lines.

A real-time read/write motion picture has been demonstrated by hole-burning holography using cryogenic Eu3+: Y2SiO5 crystal. In a holographic configuration the laser frequency was continuously scanned within the 7F0-5D0 absorption line while the object was in motion. This movie has no picture frames, and therefore is temporally continuous. This feature allows realization of high-speed and high-time-resolution motion recording.

To express period-doubling, intermittency and period-adding chaos observed in the thyristor, we propose a simple model which describes a first return map based on experimental data. This model can express whole the aspects observed in the thyristor through changing a couple of parameters in the map function. Simulated bifurcation diagram reproduced experimental results well in its qualitative nature.