Electromagnetic plane wave scattering by a loaded trough on a ground plane has been analyzed by Kobayashi and Nomura's method. The field in each region is expressed first in terms of appropriate eigen functions, whose excitation coefficients are determined by the continuity condition across the aperture of the trough. Simple far field expression which is suitable for numerical calculation for small aperture cases has been derived. Scattering far field patterns and radar cross section are calculated and compared with those obtained by other methods. Good agreements have been observed for all incident angles.

This paper describes a procedural detailed compaction method for the symbolic layout design of CMOS leaf cells and its algorithmic aspects. Simple symbolic representations that are loosely designed by users in advance are automatically converted into densely compacted physical patterns in two phases: symbolic–to–pattern conversion and segment–based detailed compaction. Both phases are executed using user-defined procedures and a specified set of design rules. The detailed compaction utilizes a segment–based constraint graph generated by an extended plane sweep method where various kinds of design rules can be applied. Since various kinds of basic operations can be applied to the individual segments of patterns in the procedures, the detailed procedure for processing can be described in accordance with fabrication process technologies and the corresponding sets of design rules. This combined stepwise procedure provides a highly flexible framework for the symbolic layout of CMOS leaf cells. The proposed approach was implemented in a symbolic layout system called CAMEL. To date, more than 300 kinds of symbolic representations of CMOS leaf cells have been designed and are stored in the database. Using several different sets of design rules, symbolic representations have been automatically converted into compacted patterns without design rule violations. The areas of those generated patterns were averaged at 98% of the manually designed patterns. Even in the worst case, the increases in area were less than about 10% of the manually designed ones. Furthermore, since processing times are much shorter than manual design periods, for example, 300 kinds of symbolic representations can be converted to corresponding physical patterns in only a day. It is evident, through these practical design experiences with CAMEL, that our approach is more flexible and process–tolerant than conventional ones.

This paper presents a cost-effective network for very large ATM cross-connects. In order to develop it, we propose the delta network with expanded middle stages. This proposed network is the intermediate network between a nonblocking network and the delta network with respect to the cost of hardware and internal blocking probability. Using this network, we explore the tradeoff between the cost and internal blocking probability, and derive the optimum configuration under temporarily deviating traffic. Internal blocking occurs when input traffic temporarily deviates from its average value. However, we cannot evaluate the internal blocking probability by using conventional traffic models. In this paper, we adopt temporarily deviating traffic such that all traffic is described as the superposition of the paths which are defined by traffic parameters. As can easily be seen, the path corresponds to virtual path (VP) or virtual channel (VC). Therefore, we believe that our model describes actual traffic more exactly than conventional models do. We show that the optimum configuration is the proposed network whose expansion ratio γ=3 when the maximum number of paths that can be accommodated in one link is greater than 22. This network achieves the internal blocking probability of 10-10. As an example of this network, we show that the proposed network of size 7272 is constructed with only 40% of the hardware required by the nonblocking network.

Recently actual use of the OSI standardized protocols has begun on client-server systems of LANs, and reduction of OSI protocol overheads in high-speed networks has become more important. We studied a parallel-processing architecture for Message Handling System (MHS), which requires a large amount of protocol processing and is expected to be used widely. We implemented a prototype MHS server with performance scalable to number of CPUs, by porting an existing MHS software with minimum modification. This paper reports on the parallel processing scheme, hardware and software architecture of the prototype, as well as evaluation of the scheme based on measurement and simulation.

We modified the adaptive fuzzy classification algorithm (AFC), which allows fuzzy clusters to grow to meet the demands of a given task during training. Every fuzzy cluster is defined by a reference vector and a fuzzy cluster radius, and it is represented as a shape of hypersphere in pattern space. Any pattern class is identified by overlapping plural hyperspherical fuzzy clusters so that it is possible to approximate complex decision boundaries among pattern classes. The modified AFC was applied to recognize handwritten digits, and performances were shown compared with other neural networks.

The transistor action with negative differential resistance (NDR) of a nanometer-thick metal (CoSi2)/insulator (CaF2) resonant tunneling transistor is discussed for two transistor structures. These transistors are composed of metal-insulator (M-I) heterostructures with two metallic (CoSi2) quantum wells and three insulator (CaF2) barriers grown on an n-Si (lll) substrate. One of the two structures has the base terminal connected to one of the quantum wells next to the collector, and the other, to one next to the emitter. Although base resistance is high maybe due to the damage caused during the fabrication process, the two transistors show different characteristics, as expected theoretically. Transfer efficiency α (= IC/IE) close to unity was obtained at 77 K for electrons through the resonant levels in M-I heterostructures.

Ultrafast MR imaging (e.g., echo-planar imaging) acquires all the data within only several tens of milliseconds. This method, however, is affected by static magnetic field inhomogeneities and chemical shift; therefore, a high degree of field homogeneity and water and fat signal separation are required. However, it is practically impossible to obtain an homogeneous field within a subject even if in vivo shimming has been performed. In this paper, we describe a new ultrafast MR imaging method called Ultrafast Single-shot water and fat Separated Imaging (USSI) and a correction method for field inhomogeneities and chemical shift. The magnetic field distribution whthin the subject is measured before thd scan and used to obtain images without field inhomogeneity distortions. Computer simulation results have shown that USSI and the correction method can obtain water and fat separated images as real and imaginary parts, respectively, of a complex Fourier transform with a single-shot scan. Image quality is maintained in the presence of field inhomogeneities of several ppm similar to those occurring under practical imaging conditions. Limitations of the correction method are also discussed.

Advanced Traveller Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) require real-time traffic data to observe and control the trafic flow. Still, there is a lack of proficient traffic monitoring systems. One method to collect such data is using particular equipped vehicles, called probes, transmitting experienced travel times to base stations which in turn are connected to a traffic control center. In this paper we analyse the performance of a radio network for collecting real-time traffic data from probes. The results reveal that random transmission of traffic reports is a (spectrum) efficient, inexpensive and flexible method for collecting road traffic data that can provide reliable traffic monitoring.

For the study of the biological effects of ELF (Extremely Low Frequency) electric fields, the perception mechanism of ELF electric fields was analyzed. When a human body is exposed to an electric field, the hair on the body surface moves due to the electric force exerted on the hair. In theoretical analysis, it was shown that the force is approximately proportional to the dielectric constant of hair and the spatial gradient of the square of the electric field at the hair. The dielectric constant of hair was measured with different temperatures and humidities of the surrounding air. A technique was developed to estimate the electric force exerted on a hair during the field exposure. After experiments with model hair, the technique was applied to a body hair of a living human being. It was found that the force increased with field strength and relative humidity. The variations of the force agreed well with those expected from the theoretical analysis and the measurement of hair dielectric constants. These results explain the cause of the reported variation in the threshold of biological effects of an electric field. The results will help to establish a practical safety standard for the held exposure.

An estimation method for efficiently calculating the field intensity in the Fresnel region of broadside colinear array antennas is developed, and its performance is experimentally verified. The calculation utilizes only the antenna design data, and is readily applicable to arbitrary array antennas. This method can provide a safety protection zone in the proximity of array antennas, in order to protect radio communication personnel and general public from the potentially hazardous radiofrequency exposure.

The studies on the biological effects of ELF electric fields conducted in Japan are reviewed. Among international studies, they are characterized as the studies from the viewpoint of bioengineering. In early studies, the safety standard of high voltage transmission lines was determined by a distinct biological effect, i.e., the sensation of the spark discharge caused by electrostatic induction. In numerical analysis, the field coupling to both animal and human bodies became well understood. Some new measurement techniques were developed which enabled us to evaluate the field exposure on a human body. A system was developed to realize the chronic exposure of an electric field on mice and cats. An optical telemetry technique was developed to measure the physiological response of an animal when it was exposed to an electric field. An ion-current shuttle box was developed to investigate the behavioral change of a rat when it was exposed to an ion-current as well as an electric field. In animal experiments, a mechanism of sensing the field was investigated. The cause of the seasonal change of field sensitivity was found. In cases of chronic exposure, suppression of growth was suspected. In shuttle box studies, an avoidance behavior from an ion-current was quantified. To find whether there are any adverse or beneficial effects of the field exposure on human beings, further study is required to clarify the mechanisms of the biological effects.

The blocking probabilities of n64Kb/s multi-slot calls are generally much higher than that of single slot calls. In order to improve these blocking probabilities of multi-slot calls, we propose a scheme to limit the number of time slots to be searched for lower rate calls. We analyze the performance of our scheme in a double-buffered time-space-time switching network which accommodates multi-slot calls as well as single-slot calls. The proposed method yields the reduced blocking probabilities of multi-slot calls, the increased traffic handling capacity and the reduced CPU processing load, compared with those of the conventional methods.

In this paper, we study a dynamic bandwidth control which is expected an effective use of network resources in transmitting highly bursty traffic generated by, e.g., interconnected LAN systems. First, a new LAN traffic model is proposed in which correlation of not only packet interarrival times but also packet lengths are considered. An analytic model for a LAN-ATM gateway is next introduced. It employs the dynamic bandwidth control using the proposed LAN traffic model and some performance measures are derived by it. The analytic model takes into account the probability that a bandwidth increase request may be rejected. Finally, some numerical examples are provided using the analysis method and performance comparisons between the dynamic and fixed bandwidth controls are made. As a result, it is quantitatively indicated that () if the equivalent bandwidth is used in average, the dynamic bandwidth control keeps packet and cell loss rates one to two orders lower than the fixed bandwidth control, () when the more strict QOS in terms of loss rate is requested, the dynamic bandwidth control can become more effective.

This paper describes a new method to estimate traffic load of communication nodes, such as switching systems. The new method uses the system identification, which is often used in designing control systems of real systems. First, this paper makes clear that, under certain conditions, the input and output relation of a communication system, which is composed of a number of communication nodes, is formulated into a dynamic state equation that is classed as a time-invariant, single-input single-output, discrete-time system. Next, it is explained that traffic load information is estimated by identifying the dynamic state equations of the communication system. Then, the traffic load estimator is synthesized using the system identification in it. Finally, it is clarified by computation simulations that the proposed method is very applicable in estimating the traffic load of each communication node.

Dislocation-free thin silicon layers are created on the three kinds of substrates such as oxide film, synthetic quartz glass and sapphire. They are bonded with silicon wafers using hydrogen bonding at room temperature but without any adhesive, and their bonding are changed into covalent bonding at elevated temperature. Thick (2 µm) silicon layers are first produced by surface grinding and polishing, and then thinned to 0.1 µm by plasma assisted chemical etching (PACE). A multiple repeated process of thinning the silicon layer and annealing the bonded silicon/quartz and silicon/sapphire interface is applied for tight bonding between a silicon wafer and a quartz wafer, and a silicon wafer and a sapphire wafer which have different thermal expansion coefficients. In case of bonding with sapphire, oxide with 200 in thickness plays an important role in the preventions of void formation and diffusion of interface contaminants into the silicon layer.

Electronics and automobiles were bound together by the introduction of emission regulations in the 1970's. The rapid progress of control technology and semiconductors that typify microcomputers has brought still closer relations between them. Without electronics, it would be impossible to realize features such as pursuit of comfort and environmental and safety measures which should be added to the automobile's fundamental features. In looking ahead to the future, the role of electronics in achieving electric automobiles and the ultimate goal of "automatic driving" is ever-increasing. Everyone knows that automobiles have become indispensable in our lives. In the future, the role of electronics will become increasingly important in order to evolve automobiles even further to allow harmonization with society.

To realize Broadband ISDN, which provides multi-media services, ATM (Asynchronous Transfer Mode) has been standardized by CCITT and the development of the system is accelerating towards the 21st century. The packet-oriented information transfer based on fixed size blocks called cells provides a very flexible allocation of transmission capacity to different connections. On the other hand, to ensure the QoS (Quality of Service) for all established connections it is necessary to monitor and regulate the input traffic from each user based on usage parameters which are negotiated between user and network at connection set-up, i.e., a policing function is required. In this paper some requirements for a policing function will be given. Accuracy of the policing decision for violating and well-behaving sources, tolerance with respect to cell delay variation (CDV) which is caused by multiplexing functions between the source terminal and the policing device, time to detect arriving violating cells, implementation complexity, and amount, i.e., cost effectiveness, are discussed mainly. We present simulation results for five policing mechanisms, Leaky Bucket (LB), Jumping Window (JW), and Moving Window (MW) which have been already well-known, Pseudo Jumping Window (PJW), and Pseudo Moving Window (PMW) which are proposed mechanisms. PJM and PMW mechanisms required a pseudo cell buffer with finite queueing capacity to the corresponding JW and MW mechanisms, respectively. These two mechanisms can be expected as advanced methods from view points of the accuracy of the policing for long-term fluctuated compliant source, fast reaction ability and restrictness to long burst traffic comparing with the above existing methods. We compare the five mechanisms based on the above requirements and show that the PJW and the LB are the most effective mechanisms for mean rate policing in ATM networks.

This paper presents a method for verifying safety property of a communication protocol modeled as two extended communicating finite-state machines with two unbounded FIFO channels connecting them. In this method, four types of atomic formulae specifying a condition on a machine and a condition on a sequence of messages in a channel are introduced. A human verifier describes a logical formula which expresses conditions expected to be satisfied by all reachable global states, and a verification system proves that the formula is indeed satisfied by such states (i.e. the formula is an invariant) by induction. If the invariant is never satisfied in any unsafe state, it can be concluded that the protocol it safe. To show the effectiveness of this method, a sample protocol extracted from the data transfer phase of the OSI session protocol was verified by using the verification system.

There have been several studies related to a reduction of the amount of computational resources used by Turing machines. As consequences, linear speed-up theorem" tape compression theorem", and reversal reduction theorem" have been obtained. In this paper, we consider reversal- and leaf-bounded alternating Turing machines, and then show that the number of leaves can be reduced by a constant factor without increasing the number of reversals. Thus our results say that a constant factor on the leaf complexity does not affect the power of reversal- and leaf-bounded alternating Turing machines

A new system of measuring the thickness of thin filn or paper using 40 kHz ultrasonic wave in air is described. The thickness of samples measured is smaller by a factor of sevreal hundreds than the wavelength of sound. Experinents with polymer and metal films and paper are described to demonstrate the measurement possibilities.