This letter presents a new design method for complex digital filters with an asymmetrical frequency response based on the frequency transformation, and shows a wave digital lattice network realization consisting of alternative connection of imaginary resistances and unit elements. As an example, a third order complex bandpass filter is designed, and its sensitivity characteristics are presented.

A new configuration is proposed for adaptive Rank Order Filters ('AROF') which adaptively extract the 'optimal rank'. The optimal rank is determined using the 'noise elimination efficiency' of ROF. The simulated results show that the AROF is more effective than the conventional rank-fixed ROFs at eliminating impulse noise.

The static and dynamic characteristics of a zero-voltage-switched half-bridge converter are analyzed quantitatively. This converter is controlled by Pulse-Width Modulation with the asymmetrical drive of a pair of semiconductor switches, and. the zoro-voltage switching is maintained by the partial resonance during the OFF interval of both switches. The effects of circuit parameters such as the input capacitance, the resonant inductance and capacitance, and the transformer leakage inductance are discussed through the comparison of analytical and experimental results.

In this paper, we study an algorithm of route optimization using the first-derivative length (FDL) path in a hybrid-switching network with movable-boundary for heterogeneous traffics, and investigate the interactions among four different classes of traffics in a time division multiplexing (TDM) network. This algorithm has some desirable properties compared with the gradient projection method or the flow deviation method. That is, it requires no initial specification of traffic flow, and the convexity of the objective function is not required. The numerical results show that the solution is close to the optimal solution and this method yields a substantial improvement in convergence time over the gradient projection method.

The telecommunication network is a complex system. So, it needs an enormous computation to control a network optimally. The fuzzy control is a very useful method to deal with such a complex problem. This paper discusses an application of hierarchical fuzzy system to dynamic routing. The performance is compared with some other control methods, and it is shown that the hierarchical fuzzy system has a good performance for a wide range.

Multicast routing problem is one of the essential problems for supporting multicast and broadcast communication service which is the most important service of the multimedia information networks. Multicast routing is the problem of finding out an adequate path which connects one source node and more than one destination node, i.e. a tree shaped path. In packet type networks, a packet for multicast communication should go through the tree shaped path as making its copies at a branching node for efficient use of network resources. However, concentration of packet copy operations at a particular node leads to performance degradation of other calls which go through this node. In this paper we propose two multicast routing algorithms which distribute packet copy operations through whole nodes in the multicast path; a link added type algorithm and a loop constructed type algorithm. Both algorithms, at first, find out an approximate solution for minimum cost path, and avoid concentration of packet copy operation at a little sacrifice of total cost in the path. Computer simulation results show that these algorithms can decrease the burden of packet copy operation per a node at the sacrifice of increase in average distance (cost) of a source-destination pair but the sacrifice of total cost is very small.

A novel physical concept "optical instanton" is presented, which exhibits a particular quasi-particle form of spatiotemporally localized light field in an intensity-dependent nonlinear medium. The physical relevance of the ultimate localization to an ultrafast nonlinear coherent process is discusseed.

It is an important topic to express solid objects in CAD, CAM and CG with a uniform way. In this article, a constructive dispersed surface points-set model (CDSPM) is proposed. CDSPM is made up by extracting the dispersed surface points sets from the simpler shapes, and then compose the points sets through a sequence of new defined Boolean set operation rules. Using these rules, solid object can be defined step by step, and the redundant data can be easily eliminated. In the article, a novel rendering method using the CDSPM medel data is introduced. A re-projection and pixel interpolation method enable us to effectively generate a reasonable image from a set of discrete surface points.

Neural network pruning is a technique to obtain a fully functional subset of a redundant network for the efficiency of computation. A new method to prune a redundant three-layered neural network by means of neural element fusion" is introduced. In contrast to conventional pruning techniques that remove unimportant portions of the network, our method fuses a pair of hidden layer units so that features accumulated in both units are preserved as possible. The pair of hidden layer units to be fused is chosen by evaluating a firing similarity. This similarity measure also informs when the pruning should be stopped. The fusing method was compared with well known unit removing" methods on computer simulations. The results show that our fusing method considerably reduces the error increase due to the pruning, even in subminimal networks where conventional methods are ineffective. This enables to cut down the total cost of computation to reach the minmal network configuration.

This paper describes an ensemble Monte Carlo simulation of Gunn domain dynamics in submicron-gate power GaAs MESFETs with a recessed gate structure. The simulated results indicate that the increase in recess width toward the drain contact region results in suppression of Gunn oscillation. This is due to the increase in domain propagation velocity by the reduced maximum electric-field in the domain. The inclusion of surface n+ region between the gate and drain regions is also proved to be effective in suppressing Gunn oscillation. Based on the simulation results, we propose a useful criterion determining whether the domain becomes traveling or stationaly. The criterion suggests that the device design allowing increased domain velocity or increased (Ndd) product is desirable for the oscillation-free, stable operation of power GaAs MESFETs.

A novel 42-GHz-band low-noise downconverter for high-definition TV (HDTV) outside broadcast links has been developed. Commercially available HEMTs are used for a low-noise preamplifier, and the parasitic reactances of bonding wires were considered when designing the input and output matching circuits for the preamplifier. A gain of 10.2 dB and a noise figure of 3.6 dB were obtained with a two-stage HEMT amplifier. The local oscillator was a parallel-feedback HEMT oscillator that directly generated a 38-GHz-band signal and was stabilized by a spherical dielectric resonator. With an output power of more than 4 dBm, a frequency drift of 2 MHzp-p was obtained over an ambient temperature range of 0 to 40. From 41.5 to 42.0 GHz, the total noise figure of the downconverter was less than 5 dB.

Asynchronous Transfer Mode (ATM) technology is expected to be used in constructing a B-ISDN. ATM networks must support a variety of services, e.g., voice, data, and image communications with different grade of service requirements. The demand for these services and their traffic characteristics, however, are not yet clear. To implement B-ISDN under this situation, it is necessary to establish a network control scheme that can' absorb the difference between the estimated traffic and the traffic that is actually offered. In ATM networks, virtual path bandwidth control is a key control scheme for absorbing this traffic estimation error, and several control algorithms have already been proposed. When we try to further utilize the VP resource by dynamically reallocating the bandwidth according to the short-term traffic variation, however, we need control schemes that are highly responsive. This is achieved by using control intervals that are shorter than the intervals over which traffic fluctuates. Control algorithms based on central controllers generally need to collect a large amount of information from geographically widespread network facilities and solve a large optimization problem. This can make them difficult to use with short control intervals in large networks. An alternative enabling the shorter control periods is to use multiple distributed controllers that use only local information. This paper proposes two new VP bandwidth control algorithms suitable for this distributed implementation. In these algorithms, decentralized controllers are located at network nodes including ATM switch (ATM-SW) or ATM cross connect (ATM-XC) function, and each controller observes the quality of the VPs relevant to it. The bandwidth is modified successively as these distributed controllers communicate with each other. We therefore call this method "successive modification method" (SMM). Numerical evaluation using a model network shows the effectiveness of these algorithms for preventing the performance degradation caused by large-scale traffic imbalance within a network. Comparison with the batch modification method (BMM), which has no feedback effect, shows that the proposed SMM with approprate control intervals can be more responsive to traffic variation over time, but is slightly inferior when network conditions are static.

A new structure GaAs power FET was designed and fabricated for high output power with sufficiently high efficiency. The undoped surface layer was introduced to achieve simultaneous increase in the maximum channel current (Imax) and the gate drain breakdown voltage (BVgd) under the large signal RF conditions. In addition the step-recessed gate structure was adopted and optimized to attain a high breakdown voltage and a high linear gain by using the two dimensional device simulator. A high fmax of 65 GHz was obtained at the "class-A" mode bias point, with the 0.55 µm gate length. The maximum fmax of 91 GHz was obtained. The test device feasibility was tested at 12 GHz and the output power/efficiency characteristics of 4.0 W/40.1% with the gain of 9.2 dB have been achieved in the "class-A" mode operation for a single chip (gate width8.18 mm). To the authors' knowledge, these RF power performances with high linear gain are the best data at 12 GHz.

A hybrid controlled dynamic routing scheme called State- and Time-dependent Routing (STR), has been proposed for telephone networks. The STR is characterized by two-level control processes: routing domain definition and call-level routing. In the routing domain definition, a set of possible alternate routes for each origin-destination node pair for each time period of the day is determined once a week by a centralized control method. In the call-level routing, each exchange determines a near-optimum alternate route from the set of possible alternate routes, which is determined in the routing domain definition process according to only the network information obtained in the call-connection processes. This paper proposes advanced call-level routing schemes for improving the performance of the basic STR. Call-by-call computer simulation of call-level routing schemes under unbalanced traffic conditions and focused overload conditions shows that the advanced schemes can achieve high performance with minimal changes of existing exchange software and operations systems. The performance of the advanced scheme based on isolated control capabilities built into each exchange is close to that of an ideal state-dependent scheme that is based on centralized control capabilities and uses data on the status of the entire network.

The equivalent circuit of ion projection-driven EPD is derived from the property of the ion current, and its adequateness is shown by the agreement of the voltage applied to the suspension calculated from the equivalent circuit and the property of the contrast ratio. Then, the improvement of the contrast ratio of the new suspension prepared on the basis of the idea by considering the equivalent circuit is described.

A divide-four static frequency divider is fabricated to evaluate the ultra-high-speed performance of Au/WSiN gate GaAs MESFETs. The divider consists of two T-type flip-flops (T-F/F) ans three buffers based on low-power source-coupled FET logic (LSCFL). The divider operates up to 31.4 GHz at room temperature at power dissipation of 150 mW per T-F/F using Au/WSiN gate GaAs MESFETs well scaled down to 0.3 µm gate-length.

This paper evaluates the performance of the statistical multiplexer with selective cell discarding (SCD) control in asynchronous transfer mode (ATM) networks. The multiplexer integrates delay-sensitive traffic such as voice or video and loss-sensitive traffic such as data, for which cell arrival processes are of bursty nature. The SCD control scheme is incorporated to prevent the systems from congestion as well as improve the system efficiency. It is based on the embedded ADPCM coding technology to packetize the delay-sensitive (voice & video) information into two kinds of cells: more significant part (MSP) cells and less significant part (LSP) cells, and priority is assigned to the MSP cells. When the system congestion occurs, the LSP cells are selectively discarded to reduce the congestion. In this paper, by approximating the two types of bursty inputs with respective Markov modulated Poisson processes (MMPP) and the fixed cell service time with k-Erlang distribution, we model the system under consideration as a queueing model MMP1[x]+MMPP2/Ek/1/m(m1), . Such a queueing model is analyzed by means of the matrix-analytic method, and the individual performance measures are derived. Numerical examples are shown to demonstrate the effectiveness of the SCD control scheme.

A novel expression for equivalent edge currents including second-order diffraction is proposed for far zone scattering from a flat plate. The ray tracing is greatly simplified by utilizing the concepts of fictitious edges. As incorporated in the modified strip representation, it can predict finite fields everywhere including SB/RB and caustics. Excellent accuracy is demonstrated numerically by comparing it with exact or the moment method solutions for diffraction from a disk and a square plate. Especially, the effects of the second-order diffraction near the plane containing the scatterer are precisely predicted. The potential of these simplest currents is as high as those of other sophisticated methods such as PTD and New Corner Diffraction.