In scheduling problem for automatic assembly, planning of task sequence is closely related with resource allocation. However, they have been separately carried out with little interaction in previous work. In assembly planning problem, there are many feasible sequences for one mechanical product. In order to find the best assembly sequence, we have to decide the cost function for each task a priori and make decision based on summation of costs in sequence. But the cost of each task depends on the machine which executes the allocated task and it becomes difficult to estimate an exact cost of each task at planning stage. Moreover, no concurrent operation is taken into account at planning stage. Therefore, we must consider the sequence planning and the machine allocation simultaneously. In this paper, we propose a new scheduling method in which sequence planning and machine allocation are considered simultaneously. First of all, we propose a modeling method for an assembly sequence including a manufacturing environment. Secondly, we show a guideline in order to determine the estimate function in A* algorithm for assembly scheduling. Thirdly, a new search method based on combination of A* algorithm and supervisor is proposed. Fourthly, we propose a new technique which can take into consider the repetitive process in manufacturing system so as to improve the calculation time. Finally, numerical experiments of proposed scheduling algorithm are shown and effectiveness of proposed algorithm is verified.

It is important to test the various kinds of interconnect faults between chips on a card/module. When boundary scan design techniques are adopted, the chip to chip interconnection test generation and application of test patterns is greatly simplified. Various test generation algorithms have been developed for interconnect faults. A new interconnect test generation algorithm is introduced. It reduces the number of test patterns by half over present techniques. It also guarantees the complete diagnosis of multiple interconnect faults.

We show that under some conditions an attacker can break the public-key cryptosystem proposed by J. Schwenk and J. Eisfeld at Eurocrypt '96 which is based on the difficulty of factoring over the ring Z/nZ [x], even though its security is as intractable as the difficulty of factoring a rational integer. We apply attacks previously reported against RSA-type cryptosystems with a low exponent to the Schwenk-Eisfeld cryptosystem and show a method of breaking the Schwenk-Eisfeld signature with a low exponent.

In a DC 50 V/5 A circuit, the relationship between the number of breaking arcs and the spatial distribution of the spectral intensity of breaking arcs of long duration near the cathode in palladium contact were examined through substitution of the contact surfaces of three different shapes: flat and spherical (1 mm radius and 2 mm radius). Findings show the distribution of spectral intensity in Pd arcs to be influenced remarkably by the shape of contact surface and the number of breaking arcs. However, the temperature of Pd arcs was affected neither by the shape of contact surface nor by the number of breaking arcs. The metal-vapor quantity present differed for flat and spherical surface contacts; however, it was not affected by the radius of the curved contact surfaces or by the number of breaking arcs. Additionally, the longer the duration of the breaking arc, the more metal-vapor was presented in the beginning of the arc. Furthermore, arc tracks on contact surfaces were observed with microscopes, clarifying that the relationship between the area of the clouded white metal on the cathode and the shape of contact surface is the same as the relationship between the existent area of measured spectra and the shape of the contact surface.

Method schemas were proposed as a formal model of object-oriented languages. A method schema S is called consistent if, for each method invocation during the execution of S, a method definition to be bound to the invoked method name is uniquely determined. However, the consistency testing problem is known to be undecidable in general. This paper presents an algorithm which analyzes the consistency of a given method schema. The algorithm decides the consistency problem in polynomial time for monadic method schemas. We also provide an incremental algorithm for testing consistency after updates of a method schema.

Many `output-scheduling' algorithms have been proposed for improving the performance of input queueing asynchronous transfer mode (ATM) switches, whereby cells from different random-access input queues destined for the same output can be scheduled for non-conflicting transmissions. An optimal output-scheduling algorithm, one with the full coordination of transmissions to all outputs, can approach the performance of output queueing. Because of the complexity of such an optimal scheduler, output schedulers proposed in the literature are without such coordination. We propose a simple way to incorporate such a full coordination in output-scheduling with much simple hardware, for small size switches. Throughput of the input queueing switch thus approaches that of the output queueing switch, without speed-up, input/output grouping or complicated hardware. To make the output-scheduling algorithm fast enough, we incorporate parallelism and pipelining. We perform detailed simulation study of the performance of the input queueing switch with the proposed scheduling algorithm.

Arc and contact resistance characteristics of Ag and Pd contacts were determined in several kinds of dielectric liquids, such as distilled water, methanol and n-hexane, under the inductive load condition. The experimental results showed that arc discharge types are dependent on dielectric liquids. A steady arc develops in air under this test condition. However, it was found that not the steady arc but the showering arc occurs in distilled water and methanol at a low load current. It was demonstrated that this phenomenon is caused by the high capacitance generated by the ambient dielectric liquid. Also, in almost all cases, the contact resistance behavior in dielectric liquids is satisfactory because metal spots remain on the contact surface. However, in n-hexane, the contact resistance tends to deteriorate, particularly for the Ag contact, with increasing load current. It seems that the deterioration of contact resistance is caused by carbon included in n-hexane.

Time series prediction is very important technology in a wide variety of fields. The actual time series contains both linear and nonlinear properties. The amplitude of the time series to be predicted is usually continuous value. For these reasons, we combine nonlinear and linear predictors in a cascade form. The nonlinear prediction problem is reduced to a pattern classification. A set of the past samples x(n-1),. . . ,x(n-N) is transformed into the output, which is the prediction of the next coming sample x(n). So, we employ a multi-layer neural network with a sigmoidal hidden layer and a single linear output neuron for the nonlinear prediction. It is called a Nonlinear Sub-Predictor (NSP). The NSP is trained by the supervised learning algorithm using the sample x(n) as a target. However, it is rather difficult to generate the continuous amplitude and to predict linear property. So, we employ a linear predictor after the NSP. An FIR filter is used for this purpose, which is called a Linear Sub-Predictor (LSP). The LSP is trained by the supervised learning algorithm using also x(n) as a target. In order to estimate the minimum size of the proposed predictor, we analyze the nonlinearity of the time series of interest. The prediction is equal to mapping a set of past samples to the next coming sample. The multi-layer neural network is good for this kind of pattern mapping. Still, difficult mappings may exist when several sets of very similar patterns are mapped onto very different samples. The degree of difficulty of the mapping is closely related to the nonlinearity. The necessary number of the past samples used for prediction is determined by this nonlinearity. The difficult mapping requires a large number of the past samples. Computer simulations using the sunspot data and the artificially generated discrete amplitude data have demonstrated the efficiency of the proposed predictor and the nonlinearity analysis.

The showering arc waveforms generated when contact is being separate have poor reproducibility whose causes are not sufficiently clear. This paper describes that the contact surface conditions which change with the number of contact operations are deeply related to the showering arc waveforms. First, it is experimentally shown that the contacts' surface roughness increases with the number of contact operations, and the growth model of contact surface roughness is proposed based on the change of contact resistance for the number of contact operations. Second, the growth model of molten metal bridge is proposed based on the fact that the showering arc waveforms change with the number of contact operations and the evaluation indexes of showering arc are proposed.

Repeaterless transmission system design employing remote pumping in a single fiber is clarified. The design is aimed to realize cost effective submarine transmission systems with easy maintenance. Remote pumping in a single fiber can extend repeaterless transmission distance without decreasing the system capacity per cable. It is applicable for high-count-fiber cable such as the 100-fiber submarine cable already developed. A simple but effective system configuration is presented that uses remote pumping from receiver end; both remote-pre erbium-doped fiber (EDF) amplification and backward pumping Raman amplification are employed. Stable transmission can be obtained without optical isolators, therefore the optical time domain reflectometry (OTDR) method is supported by this system. Three fiber configurations, which consist of dispersion shifted fiber (DSF), pure silica core fiber (PSCF) and a combination of DSF and PSCF, are examined to compare system performance. Remote-pre EDF is optimized in terms of length and location from receiver end by optical SNR (OSNR) calculations. Maximum signal output power is also determined through a waveform simulation based on the split-step Fourier method, in order to avoid waveform distortion caused by the combined effect of self-phase modulation (SPM) and group velocity dispersion (GVD). Through these calculations and simulations, we confirm the proposed repeaterless transmission system performance of 600Mbit/s-451 km with PSCF, 2. 5 Gbit/s-407 km with DSF + PSCF, and 10 Gbit/s-376 km with DSF+PSCF, which include system margin.

Conventional fast block-matching algorithms, such as TSS and DSWA/IS, are widely used for motion estimation in the low-bit-rate video coding. These algorithms are based on the assumption that when searching in the previous frame for the block that best matches a block in the current frame, the difference between them increases monotonically when a matching block moves away from the optimal solution. Unfortunately, this assumption of global monotonicity is often not valid, which can lead to a high possibility for the matching block to be trapped to local minima. On the other hand, monotonicity does exist in localized areas. In this paper, we proposed a new algorithm called Peano-Hilbert scanning search algorithm (PHSSA). With the Peano-Hilbert image representation, the assumption of global monotonicity is not necessary, while local monotonicity can be effectively explored with binary search. PHSSA selects multiple winners at each search stage, minimizing the possibility of the result being trapped to local minima. The algorithm allows selection of three parameters to meet different search accuracy and process speed: (1) the number of initial candidate intervals, (2) a threshold to remove the unpromising candidate intervals at each stage, and (3) a threshold to control when interval subdivision stops. With proper parameters, the multiple-candidate PHSSA converges to the optimal result faster and with better accuracy than the conventional block matching algorithms.

One of the ways to execute a processing algorithm in high speed is parallel processing on multiple computing resources such as processors and functional units. To identify the minimum number of computing resources, the most important is the scheduling to determine when each operation in the processing algorithm is executed. Among feasible schedules satisfying all the data dependencies in the processing algorithm, an overlapped schedule can achieve the fastest execution speed for an iterative processing algorithm. In the case of processing algorithms with operations which are executed on some conditions, computing resources can be shared by those conditional operations. In this paper, we propose a scheduling method which derives an overlapped schedule where the required number of computing resources is minimized by considering the sharing by conditional operations.

This study presents a novel window-based token protocol which supports two priority levels of ATM-like bursty traffic. The proposed protocol ensures that packets arriving during a given window period are always transmitted prior to those arriving during subsequent window periods. During which periods, high priority (delay-sensitive) packets are served by a nonpreemptive priority service discipline. Under this window-based token protocol, the delay bounds for packets of both priority levels are derived when the traffic streams satisfy the traffic descriptors. Hence, a call admission control policy based on delay bounds can be employed to guarantee QoS parameters such as the packet delay and packet loss-free requirement for each traffic stream. The protocol proposed herein can achieve tighter delay bounds than the IEEE 802. 5 token protocol and the timed token protocol used in FDDI, particularly for high priority bursty traffic, thereby making it highly attractive for supporting not only real-time multimedia VBR or CBR services such as in ATM networks but also ATM encapsulation such as in Cells In Frames (CIF) protocol.

This paper describes a method for analyzing active impedance, i. e. equivalent resistance and equivalent reactance, of a narrow-band transistor Colpitts crystal oscillator. This oscillator, employing an AT-cut resonator filter, has a very narrow-band width and an achievement of extremely low phase-noise characteristics is expected. The analysis proposed is based on an algebraic formula, which employs a nonlinear approximation for transistor gm, and a simplified circuit model. Calculated results are compared with the experimental results in the frequency characteristics of the oscillator active impedance with changing the driving signal current. Good agreement between the calculation and experimental results shows that the proposed technique is suitable for designing Colpitts crystal oscillators with resonator filters. In addition we apply this technique to the analysis of dual-mode crystal oscillators.

We investigate the relaxation oscillation characteristics of an actively mode-locked fiber laser and a novel stabilizing method of the laser theoretically and experimentally. The stabilizing method controls cavity length to suppress the rf power of the relaxation oscillation frequency of the laser output, and can directly monitor the stability of the laser to ensure the most stable operation. With this method, the rf power ratio between mode-locking frequency and the background noise can be kept to more than 70 dB, and highly stable transform-limited pulse generation is achieved. Bit-error-free operation at 6. 3 GHz over 10 hours is successfully demonstrated. The stability of the center wavelength of the laser output and the required accuracy of cavity control for high-speed laser operation are also discussed.

It is shown from the Hilberts theory that if the real function Π(θ) has no zeros over the interval [0, 2π], it can be factorized into a product of the factor π+(θ) and its complex conjugate π-(θ)(=). This factorization is tested to decompose a real far-zone field pattern having zeros. To this end, the factorized factors are described in terms of bicomplex mathematics. In our bicomplex mathematics, the temporal imaginary unit "j" is newly defined to distinguish from the spatial imaginary unit i, both of which satisfy i2=-1 and j2=-1.

Per-Virtual Connection (VC) queueing allows an ATM switch to schedule cells to be transmitted on a link based on their VC. This alternative to the traditional First-In-First-Out(FIFO)queueing, in which cells from different VCs of the same priority are stored in a common queue, is implemented by some switch manufacturers. This paper assesses the merits of per-VC scheduling in regards to capacity, traffic shaping, and interworking with traffic management mechanisms such as connection admission control (CAC) and use of queue thresholds. The paper also discusses the conditions which favor the use of per-VC scheduling.

Asynchronous Transfer Mode (ATM) networks are expected to support a diverse mix of traffic sources requiring different Quality Of Service (QOS) guarantees. This paper initially examines several existing scheduling disciplines which offer delay guarantees in ATM switches. Among them, the Earliest-Due-Date (EDD) discipline has been regarded as one of the most promising scheduling disciplines. The EDD discipline schedules the departure of a cell belonging to a call based on the delay priority assigned for that call during the call set-up. Supporting n delay-based service classes through the use of n respective urgency numbers D0 to Dn-1 (D0D1 Dn-1), EDD allows a class-i cell to precede any class-j (j>i) cell arriving not prior to (Dj-Di)-slot time. The main goal of the paper is to determine the urgency numbers (Dis), based on an in-depth queueing analysis, in an attempt to offer ninety-nine percentile delay guarantees for higher priority calls under various traffic loads. In the analysis, we derive system-time distributions for both high- and low-priority cells based on a discrete-time, single-server queueing model assuming renewal and non-renewal arrival processes. The validity of the analysis is justified via simulation. With the urgency numbers (Dis) determined, we further propose a feasible efficient VLSI implementation architecture for the EDD scheduling discipline, furnishing the realization of QOS guarantees in ATM switches.

Widely tunable coherent terahertz (THz)-wave generation was successfully demonstrated based on the laser light scattering from the lowest A1-symmetry polariton mode by using a Q-switched Nd:YAG laser pumping. This method exhibits multiple advantages like wide tunability (frequency: 0. 9-2. 2 THz), coherency and compactness of its system. In this paper, the general performances of this THz-wave generator, as well as the recent development of the system and its application are reported. Measurements of tunability, coherency, power, polarization, radiation angle, and divergence are shown. The cryogenic cooling of the crystal was performed in addition, and a more than one hundred times higher THz-wave output was observed. A spectroscopic application of our wave source is demonstrated by measuring the water vapor absorption.

The development of a far-infrared imaging system based on ultrafast THz time-domain spectroscopy has opened a new field of applications of femtosecond technology. We describe the principle of this new imaging technique and report recent progress to augment the possibilities of "T-ray" imaging. These include sub-wavelength-resolution near-field imaging and three-dimensional tomographic reconstruction of a samples refractive index profile.