We present a cascade neural network for blind source extraction. We propose a family of unconstrained optimization criteria, from which we derive a learning rule that can extract a single source signal from a linear mixture of source signals. To prevent the newly extracted source signal from being extracted again in the next processing unit, we propose another unconstrained optimization criterion that uses knowledge of this signal. From this criterion, we then derive a learning rule that deflates from the mixture the newly extracted signal. By virtue of blind extraction and deflation processing, the presented cascade neural network can cope with a practical case where the number of mixed signals is equal to or larger than the number of sources, with the number of sources not known in advance. We prove analytically that the proposed criteria both for blind extraction and deflation processing have no spurious equilibria. In addition, the proposed criteria do not require whitening of mixed signals. We also demonstrate the validity and performance of the presented neural network by computer simulation experiments.

With the advance of computer technologies, mobile computers can hold many local resources in themselves. In many cases it is impossible to announce local resources on them because almost information announcement systems are not designed for them. In this paper, an information announcement system for mobile computers based on WWW is proposed. The system efficiently announces resources on mobile computers independently of whether they are connected to a network or not, and wherever they are connected. The system can also select suitable announcement methods according to the type of resources. We implement a prototype of proposed system and evaluate it. The result of evaluation confirms effectiveness of the proposed system.

This paper is concerned with Wiener-Hopf solutions to the electromagnetic wave scattering by a conducting finite thin plate when the incident wave is not a plane wave. The incident wave is approximated in terms of a piece-wise plane wave on a divided small section of the conducting plate. The final expressions are given in an analytically compact form and the results are accurate as long as the plate width is greater than the wavelength and the divided section is so small that we can expand the incident wave by a piece-wise plane wave. A criterion for the ray tracing method is also proposed.

This paper proposes a fast scheduling algorithm based on gradual time-frame reduction for datapath synthesis of digital signal processing hardwares. The objective of the algorithm is to minimize the costs for functional units and registers and to maximize connectivity under given computation time and initiation interval. Incorporating the connectivity in a scheduling stage can reduce multiplexer counts in resource binding. The algorithm maximizes connectivity with maintaining low time complexity and obtains datapath designs with totally small hardware costs in the high-level synthesis environment. The algorithm also resolves inter-iteration data dependencies and thus realizes pipelined datapaths. The experimental results demonstrate that the proposed algorithm reduces the multiplexer counts after resource binding with maintaining low costs for functional units and registers compared with eight conventional schedulers.

One of the important challenges in the design of ATM networks is how to provide quality-of-service (QoS) while maintaining high network resource utilization. In this paper, we discuss the role of real-time traffic characterization in QoS control for ATM networks and review several approaches to the problem of resource allocation. We then describe a particular framework for QoS control in which real-time measurements of a connection stream are used to determine appropriate parameters for usage parameter control (UPC). Connection admission control (CAC) is based on the characterization of the aggregate stream in terms of the individual stream UPC descriptors, together with real-time measurements.

We propose a mechanically tunable passively mode-locked semiconductor laser with a high repetition rate using a simple configuration with a moving mirror located very close to a laser facet. This scheme is demonstrated for the first time by a novel micromechanical laser consisting of an InGaAsP/InP multisegment laser with a monolithic moving micro-mirror driven by an electrostatic comb structure. The main advantage of this laser is the capability of generating high-quality mode-locked pulses stabilized by a phase-locked loop (PLL) with low residual phase noise in a wide repetition-rate tuning range. This paper describes the basic concept and tuning performances utilizing the micromechanical passively mode-locked laser in 22-GHz fundamental mode-locking and in its second-harmonic mode-locking.

Let {Xk}k=- be a stationary and ergodic information source, where each Xk takes values in a standard alphabet A with a distance function d: A A [0, ) defined on it. For each sample sequence X = (, x-1, x0, x1, ) and D > 0 let the approximate D-match recurrence time be defined by Rn (x, D) = min {m n: dn (Xn1, Xm+nm+1) D}, where Xji denotes the string xixi+1 xj and dn: An An [0, ) is a metric of An induced by d for each n. Let R (D) be the rate distortion function of the source {Xk}k=- relative to the fidelity criterion {dn}. Then it is shown that lim supn-1/n log Rn (X, D) R (D/2) a. s.

Coupling in time domain between two non-parallel transmission lines of finite length is analyzed by using a circuit concept. Coupling equations based on the Maxwell's equations for lossless transmission lines in a homogeneous medium are written by a set of non-homogeneous differential equations including distributed source terms produced by external electromagnetic fields. The forcing terms are expressed by vector potentials generated by currents in the line section and at the transitions. A set of solutions in frequency domain is obtained by a four-port network expression with regard to the terminal voltages and currents, and can be applied to estimation of the frequency-domain crosstalk. Utilizing the inverse fast Fourier transform (FFT), the crosstalk responses between the lines is studied in time domain. Comparison of theoretical and experimental results shows the validity of the method.

This paper presents an effective and robust technique for compacting a large sequence of input vectors into a much smaller input sequence so as to reduce the circuit/gate level simulation time by orders of magnitude and maintain the accuracy of the power estimates. In particular, this paper introduces and characterizes a family of dynamic Markov trees that can model complex spatiotemporal correlations which occur during power estimation both in combinational and sequential circuits. As the results demonstrate, large compaction ratios of 1-2 orders of magnitude can be obtained without significant loss (less than 5% on average) in the accuracy of power estimates.

In this paper we develop a new family of on-line adaptive learning algorithms for blind separation of time delayed and convolved sources. The algorithms are derived for feedforward and fully connected feedback (recurrent) neural networks on basis of modified natural gradient approach. The proposed algorithms can be considered as generalization and extension of existing algorithms for instantaneous mixture of unknown source signals. Preliminary computer simulations confirm validity and high performance of the proposed algorithms.

Electroluminescent (EL) devices with mixed single layer that consist of fluorescent dyes, distylylbiphenyl derivative (DPVBi) and triphenylamine derivative (TPD), are studied. Blue light emission was observed from the device with DPVBi and TPD. White emission over 2,500 cd/m2 was observed from the devices with mixed single layer of DPVBi, TPD and dicyanomethylene derivative (DCM).

A new multiple-valued current-mode (MVCM) integrated circuit using a switched current-source control technique is proposed for a 1.5 V-supply high-speed arithmetic circuit with low-power dissipation. The use of a differential logic circuit (DLC) with a pair of dual-rail inputs makes the input voltage swing small, which results in a high driving capability at a lower supply voltage, while having large static power dissipation. In the proposed DLC using a switched current control technique, the static power dissipation can be greatly reduced because current sources in non-active circuit blocks are turned off. Since the gate of each current source is directly controlled by using a multiphase clock whose technique has been already used in dynamic circuit design, no additional transistors are required for currentsource control. As a typical example of arithmetic circuits, a new 1.5 V-supply 5454-bit multiplier based on a 0.8µm standard CMOS technology is also designed. Its performance is about 1.3 times faster than that of a binary fastest multiplier under the normalized power dissipation. A prototype chip is also fabricated to confirm the basic operation of the proposed MVCM integrated circuit.

To realize the high speed and low power CMOS Phase Locked Loop, we have developed new components of PLL: VCO and PFD. In the VCO, high speed and low power is realized with source coupled inverter pairs in the single loop three gate ring oscillator. And in the PFD, low power and small chip area are realized with the dynamic inverter. And with the simple design adjustment, both reduction of dead zone and immunity of current fluctuation at "O" output are implemented in Charge Pump. A fully CMOS PLL with these components have been designed with 0.8µ CMOS. At 622MHz operation, the power dissipation of 18mW is achieved by SPICE simulation.

In this paper, algorithms for resource allocation in an ATM node that serves heterogeneous traffic sources subject to varying Quality of Service (QoS) requirements are proposed. The node can be either a switch port or a multiplexer. Each connection is first individually treated as logical queue. Quick and efficient algorithms allocating service rate and buffer space to each connection based on traffic characteristics and QoS requirement are developed. In order to improve link and buffer utilization, the aggregate traffic is next replaced by an appropriately parameterized new traffic source that still preserves the key characteristics of the aggregate traffic. The most stringest QoS requirement among all connections is selected to be the QoS target of the new traffic source to assure that QoS of each individual connection is satisfied. Resource allocation for the aggregate traffic is determined based on the traffic parameters and QoS target of the new source. Each individually determined service rate and buffer space can be used in cell transmission scheduling and selective cell discarding. In other words, resource allocation together with two related side problems: cell transmission and cell discarding, are treated in this paper in an integrated and efficient manner. The resource allocation algorithms proposed in this paper can also be used to support Call Admission Control (CAC) in ATM networks.

This paper presents severl radio resource scheduling algorithms which aim to provide best-effort service for non-real-time unit-oriented, or message traffic. The objective of resource scheduling algorithm is to distribute radio resources between competing message traffic sources while attaining throughput as high and fair as possible for each source without any explicit quality-of-service (QoS) guarantee. Computer simulations are carried out to evaluate the performance in terms of the average of allocation plus transfer delay, the average of throughput, the variance of throughput, and the usage of resources. The message-size distributions of homepages in World-Wide-Web and e-mails obtained by actual measurement are used. Message size-based resource scheduling algorithms are found to provide high and fair throughput as well as efficient use of the resources.

High-end graphic systems with 3 million pixels require 8-bit D/A converters with more than 300-MS/s conversion rate. Furthermore, D/A converters need to operate with low supply voltage when they are integrated with large-scale digital circuits on a harf-micron CMOS process. This paper describes a 350-MS/s 8-bit CMOS D/A converter with 3.3-V power supply. A current source circuit with a delayed driving scheme is developed. This driving scheme reduces a fluctuation of internal node voltage of the current source circuit and high-speed swiching is realized. In addition to this driving scheme, two stages of latches are inserted into matrix decoder for reducing glitch energy and for enhancing decoding speed. The D/A converter is fabricated in a 0.5-µm CMOS process with single poly-silicon layer and double aluminum layers. Its settling time is less than 2.4 ns and it successfully operates at 350 MS/s.

A new GSM data protocol called high speed circuit switched data (HSCSD) have been developed by European Telecommunications Standards Institute (ETSI) for high speed file transfer and mobile video applications. HSCSD increases data rate by using multiple TDMA time slots (up to 8) instead of one time slot in the current GSM implementation. The problem of multiple time slot assignment is that blocking rate of the system will increase. This problem can be solved by flexible resource assignment where the service specifies the maximum and the minimum capacity. Based on the current available capacity of a base station, a user will be assigned any rate between the maximum and the minimum capacities. This article describes HSCSD protocol and presents four radio resource allocation strategies for HSCSD: always allocates maximum, always allocates minimum, allocates maximum unless available resources are not enough, and allocates resources according to the current blocking statistics of the base station. A simulation model is proposed to investigate the performance of these algorithms. The blocking probability, the call completion probability, and the quality of service are used to evaluate the effects of algorithms in different system behaviors.

In direction of arrival estimation, the locations of point sources are usually assumed to be fixed during the observation of data, which is reasonable in many cases. If the locations of the point sources are perturbed due to some reasons in a statistical way during the observed period and the signal sources are not far away from receiver array, however, direction of arrival estimation methods based on the fixed point source assumption may provide with incorrect results. In this paper, we propose a perturved-location source model. Under the model, an estimation method based on eigen-decomposition is investigated. In addition, the asymptotic distributions of the estimation errors of the parameters are obtained to show the statistical properties of the parameters are obtained to show the statistical properties of the estimation method.

Electronic systems are progressively replacing mechanical devices or human operation for identifying people or objects in everyday-life applications. Especially, the contactless identification systems available today have several advantages, but they cannot handle easily several simultaneously present items. This paper describes a solution to this problem, based on blind source separation techniques. The effectiveness of this approach is experimentally demonstrated, especially by using a real-time DSP-based implementation of the proposed system.

Most research on the estimation of direction of arrival (DOA) has been performed based on the assumption that the signal sources are point sources. In some real surroundings, signal source localization can more adequately be accomplished with distributed source models. When the signal sources are distributed over an area, we cannot directly use well-known DOA estimation methods, because these methods are established based on the point source assumption. In this paper, we propose a 3-dimensional distributed signal source model, in which a source is represented by two parameters, the center angle and degree of dispersion. Then, we address the estimation of the elevation and azimuth angles of distributed sources based on the parametric distributed source modeling in the 3-dimensional space.