For L 2, M 8, and transmission rate R = (log2M-1) bit/sym, a method for constructing GU trellis codes with L MPSK constellations is proposed and it is shown that the maximally achievable free distance is twice larger than it was previously reported for GU codes. Basides being geometrically uniform, these codes perform as good as Pietrobon's non-GU trellis codes with multidimensional MPSK constellations.

Genetic algorithms have been shown to be very useful in a variety of search and optimization problems. In this paper we present a genetic algorithm for maximum independent set problem. We adopt a permutation encoding with a greedy decoding to solve the problem. The DIMACS benchmark graphs are used to test our algorithm. For most graphs solutions found by our algorithm are optimal, and there are also a few exceptions that solutions found by the algorithm are almost as large as maximum clique sizes. We also compare our algorithm with a hybrid genetic algorithm, called GMCA, and one of the best existing maximum clique algorithms, called CBH. The exiperimental results show that our algorithm outperformed two of the best approaches by GMCA and CBH in final solutions.

In the proposed architecture, switching system hardware resources are allocated at the equipment level rather than at the component level of LSI chips. Equipment using these resources can thus be shared between independent systems. The efficiency of system development is improved by using structural elements called functional blocks (FBs). The hardware in each FB consists of a shared part (amicroprocessor, its peripheral circuitry, and memory) and a dedicated part that implements the specific functions of the FB. Firmware loaded into the microprocessor consists of a shared part and a dedicated part that corresponds to the hardware parts. Each FB also has its own built-in autonomous testing function to test the reliability of that FB and has its own identification function. By combining these FBs, this approach can flexibly cope with various switching system configurations for plain old telephone service (POTS), integrated services digital network (ISDN), and broad-band ISDN (B-ISDN). Tests using several types of FBs showed that the shared hardware and firmware parts of an FB can be shared between blocks. An architecture based on FBs results in a platform that can handle the hardware for various systems, making it easy to construct new switching systems.

Photovoltaic devices capable of generating more than 200 volts with an area of 1 cm2 have been developed for directly driving microactuators such as piezoelectric or electrostatic actuators. The micro-devices interconnect 285 micro cells (unit cell size: about 0.5 mm 2.0 mm) in series, and have an open circuit voltage (Voc) of 207 volts, a short circuit current (Isc) of 36.6 µA, a maximum output power (Pmax) of 4.65 mW and a fill factor (F.F.) of 0.615 under AM (Air Mass) 1.5 and 100 mW/cm2 illumination. This voltage is the highest in the world for the area of 1 cm2. The series connection is precisely processed by a focused laser beam, thereby significantly reducing the area needed for device connections. It has been confirmed that a piezoelectric polymer can be directly driven by the electrical output in evaluating the potential of the devices to be used as a microactuator's power source.

A 2.7-V Si-bipolar quadrature modulator with a 90 phase shifter consisting of a frequency doubler and a master-slave flip-flop is described. The modulator operates over a wide bandwidth (0.95 to 1.88 GHz) without any tuning or adjustments. It is implemented using 20-GHz Si-bipolar technology and dissipates 97 mW at 2.7 V. An image ratio of less than -40 dBc is obtained between 1.1 and 1.8 GHz. Moreover, third-order harmonic products are less than -40 dBc and carrier leakage is less than -30 dBc.

In this paper an analog CMOS implementation of Approximate Identity Neural Networks is suggested. In particular a one-input one-output Neural Network with 6 neurons has been designed and fabricated with a 2µm CMOS technology. Due to the small area occupied the circuit proposed for the neuron is suited for the implementation of larger networks.

The valid region for the application of the conventional Improved Circuit Theory (ICT) in the analysis of wire antennas is established. To further extend the application of ICT to the analysis of much longer antennas, Tai's trial function is used to derive new formulas for the impedance matrix. Unlike the conventional ICT trial function, Tai's trial functions lead to input impedances which are finite irrespective of antenna length. Results of the new ICT impedance formulas are comparable in accuracy with the general method of moments. Moreover, since all the elements of the new formula have been expressed in closed-form, the resulting ICT algorithm is still superior in terms of computer running time with lesser storage requirement compared to other conventional methods like method of moments. This would enhance ICT applications in CAD/CAE systems.

This letter presents a realization of active current-mode resonator with complex coefficients using CCIIs. The resonator can be used for cascade or leapfrog configuration of high-order bandpass filters with complex coefficients. For realizing the resonators, only the grounded capacitors and the grounded resistors as passive elements are required, therfore the resonator is suitable for the integrated circuit realization. The letter shows that the response error of the proposed circuit caused by nonideality of active components is more easily compensated than that of voltage-mode counterpart. Experimental result is used for verifying the feasibility of the proposed resonator.

We propose a modification of the perfect shuffle connectivity graph used in optical networks, which ensures the balance of the traffic load on the WDM channels. When applied to the simple but popular case of 8 nodes, connected through a shortest path routing algorithm, it allows to increase the aggregate capacity of more than 14%.

A CMOS programmable gain amplifier (PGA) with a swiched capacitor offset compensation circuit is described. The mean compensation error is 130µV at the input, and the standard deviation of the compensation error is 50µV. This PGA is applicable to a baseband amplifier for digital radio communication terminals.

We present a new class of trellis-codes for partial-response channel. Our code configuration is based on the coded 1 - D scheme due to Wolf and Ungerboeck. However, no precoder between a convolutional encoder and the partialresponse channel is used. A new lower bound on the minimum free squared Euclidean distance of channel code is shown. The bound is available for any PR channel with a finite response. New codes for 1 - D and (1 - D) (1 + D)2 channels are found by computer code search using the lower bound. Some of the new codes have excellent properties: a significant d2free and a small decoding complexity.

A novel adder-free architecture for realizing a small-size π/4-shift QPSK signal generator IC is presented. In order to realize an adder function, analog current-mode addition is utilized instead of digital adders. Impulse responses of a roll-off filter are stored in a ROM as a Δ-Σ modulated one-bit data stream. This can greatly reduce the die size to 0.8mm 0.8mm while maintaining high modulation accuracy. The test chip was fabricated by using the standard 0.8µm CMOS technology, and the chip achieved 1.8% vector modulation error with a 2.7V power supply.

In this paper we discuss a certain constrained optimization problem which is often encountered in the geometrical optimization. Since these kinds of problems occur frequently, constrained genetic optimization becomes very important topic for research. This paper proposes a new methodology to handle constraints using the Genetic Algorithm through a multiprocessor system (FIN) which has a self-similarity network.

In this paper, two types of improved CMRR CMOS OAs, N type and P type, without common-mode feedback and the cascode current mirrors, are proposed. The CMRR of proposed OAs are enhanced by compensating variations in tail bias current, caused by a common mode input signal, at the differential input stage, by means of feedforward controlled current source. Simulation results show that the CMRR of the proposed OAs are 20dB higher than that of conventional OAs.

We propose an nn optical switch that is suitable for flexible and reliable optical access networks and for reconfigurable optical inter-module connections in large-scale processing systems. The switch consists of an intersecting waveguide matrix, matching oil, and microactuators. Switching is based on the movement of oil due to capillary pressure, which is controlled by the microactuator. The necessary switching conditions were calculated and the results showed that both the oil volume and the microactuator position must be controlled. A trial optical switch was fabricated to test the switching principle, and switching and self-holding were both confirmed. These results show the feasibility of a very small self-holding nn optical switch that uses a waveguide matrix and microactuators made by using microfabrication technologies.

A new structure for adaptive AR spectral estimation based on multi-band decomposition of the linear prediction error is introduced and the mathematical background for the soulution of the related adaptive filtering problem is derived. The presented structure gives rise to AR spectral estimates that represent the true underlying spectrum with better fidelity than conventional LS methods by allowing an arbitrary trade-off between variance of spectral estimates and tracking ability of the estimator along the frequency spectrum. The linear prediction error is decomposed through a filter bank and components of each band are analyzed by different window lengths, allowing long windows to track slowly varying signals and short windows to observe fastly varying components. The correlation matrix of the input signal is shown to satisfy both time-update and order-update properties for rectangular windowing functions, and an RLS algorithm based on each property is presented. Adaptive forward and backward relations are used to derive a mathematical framework that serves as a basis for the design of fast RLS alogorithms. Also, computer experiments comparing the performance of conventional and the proposed multi-band methods are depicted and discussed.

This paper describes the fabrication of micro-pipes and their applications to splicing parts and optical switches using single-mode fibers. Micro-pipes having almost the same inner diameter of bare fiber (125 µm) and lengths of around 5 mm are successfully mass-produced by using micromachining technology. We fabricate various kinds of metal pipes such as Au, Cu, Ni, and an FeNi alloy by selecting the appropriate electro-plating bath. We use an Au micro-pipe having a small slitted portion running along its axis (slitted micro-pipe) to splice single-mode fibers. We also use an FeNi alloy micro-pipe to construct a single-mode fiber switch. These new single-mode fiber devices employing micro-pipes show excellent optical and mechanical characteristics. Splicing losses are in the range of 0.2-0.4 dB. The developed 1 2 latching type single-mode fiber switches exhibit a low insertion loss of 0.35 dB, a minimum switching speed of 2 ms with a driving power of 9 mW, and stable operation for more than 108 switchings without damage. A practical application of the developed switch for testing optical devices is also demonstrated.

The dispersion characteristics of two nonidentical coupled microstrip lines and N identical coupled microstrip lines are analyzed using the coupled-mode theory combined with Galerkin's moment method in spectral domain. In this approach, the solutions to the original coupled microstrips are approximated by a linear combination of eigenmode solutions associated with the isolated single microstrip, and the reciprocity relation is used to derive the coupled-mode equations. The coupling coefficients are given by the simple overlap integrals in spectral domain between the eigenmode fields and currents of the individual microstrips. It is shown that the numerical results are in very good agreement with those obtained by the direct Galerkin's moment method over a broad range of weak to moderately strong coupling.

A quantitative study is made on performance of neutron penumbral imaging with a toroidal-segment aperture, and it focused on isoplanaticity of aperture point spread function and effect of the non-isoplanaticity on the reconstructed images. The results show that the aperture point spread function is satisfactorily isoplanatic for a small field of view, while for a large field of view the point spread function is not satisfactorily isoplanatic resulting in some distortion in the reconstructed image and reduction of resolution.

Verification of timed bisimulation equivalence is generally difficult because of the state explosion caused by concrete time values. In this paper, we propose a verification method to verify timed bisimulation equivalence of two timed processes using a symbolic technique similar to [1]. We first propose a new model of timed processes, Alternating Timed Symbolic Labelled Transition System (A-TSLTS). In an A-TSLTS, each state has some parameter variables, whose values determine its behaviour. Each transition in an A-TSLTS has a quard predicate. The transition is executable if and only if its guard predicate is true underspecified parameter values. In the proposed method, we can obtain the weakest condition for a state-pair in a finite A-TSLTS, which the parameter values in the weakest condition must satisfy to make the state-pair be timed bisimulation equivalent.