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.

Type () quantification analysis was carried out in which criterion variable consisted of computerized test scores where learners inputted their answer from keyboard and explanatory variables consisted of learners' traits. As learners' traits, "academic achievement", "preference for test executing media", "keyboard input speed", "LOC" and "introversion-extraversion" were examined. It was revealed that learners who "prefer computer to paper-and-pencil as test executing media", "did well in keyboard input speed test", "have external LOC", or "took a middle position in introversion-extraversion scale" did themselves justice in computerized test compared to paper-and-pencil test.

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.

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 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.

Characteristics of a cavity-backed annular slot antenna with one point shorted are investigated. Resonance frequencies, bandwidths and radiation patterns with respect to a slot width and a slot shorting position are studied experimentally. By selecting a slot shorting position, the bandwidth of more than 10% for the input impedance and circular polarization of the bandwidth of about 3.2% for the axial ratio are obtained.

This paper presents further results on the circular Levinson algorithm for multichannel linear prediction consisting only of scalar operations. The first result is an explicit inversion formula of the covariance matrix. This is a generalization of Trench and Gohberg-Semencul formula. An application to time series modeling is also mentioned. The second one is a simple modification in the algorithm to treat the case where the covariance matrix becomes singular. An example is given how the modified algorithm works.

Several advanced call routing systems have been proposed for transit planes of PSTN. The paper addresses the question to what extent the routing sophistication increases the traffic handling capability of these planes. Situations with nominal traffic, its fluctuations, equipment failures and overloads are discussed. It turns out that a simple alternative routing system with a routing patterns reconfiguration facility will ensure a major percentage of the benefits achievable with more sophisticated routing systems.

A switched-capacitor successive-approximation analog-to-digital (AD) converter is developed which incorporates a serial digital-to-analog (DA) subconverter for generating the threshold voltage sequence. Error analysis shows that a resolution higher than 12-b is attainable with the monolithic implementation using present CMOS technologies.

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.

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 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.

There is a rapidly growing need for making high capacity digital global networks resilient to variations in traffic load and network element failures. This can be accomplished by robust network engineering and greater network flexibility. The primary vehicles for achieving network flexibility objectives are dynamic routing and/or dynamic capacity allocation techniques. This paper presents an overview of the recent progress and new challenges in developing those advanced network control methodologies for global networks that exploit revolutionary new telecommunications technologies.

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.

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.

This paper describes the research results of three dimensional parameter representation of human arm motion, image synthesis and intelligent transmission for sign language communication between Japan and China using a personal computer.

An approach for realizing mutually coupled circuits using current conveyors (CCIIs) as active elements is proposed. The realized circuits are composed of eight CCIIs, six resistors and four grounded capacitors. The values of a primary self-inductance, a secondary self-inductance and a mutual in ductance can be independently tuned by three resistors, respectively.