bluuebunny/crossref_metadata_2025 huggingface dataset:
A method of two‐dimensional filter image with a nonseparable autocovariance function
Authors: Mizuno Harunobu , Omatsu Shigeru , Soeda Takashi
Published: July 2007

Recently, various methods have been reported for two‐dimensional image enhancement with the development of satellite image and medical image processing. This paper proposes a two‐dimensional filter for the image with a nonseparable autocovariance function in order to reduce the memory storage and processing time. Also, a simple method of estimating the necessary statistics to compose the filter is considered. The proposed two‐dimensional filter is a stable one which satisfies an estimation criterion of unbiasness and minimum variance. Also, the filter introduced here is completely equivalent to the Kalman filter algorithm when the filter parameters a1, a2, a3 are such that a3 = 0 and a1 or a2 = 0. Thus, the proposed filter is a natural extension of a classical Kalman filter into a two‐dimensional system. Finally, we compare existing methods with the proposed method by simulation, and examine qualitatively the contention that the estimation accuracy and computation time of the proposed method are superior to the others.
Synthesis of lattice digital filters by the state variable method
Authors: Takizawa Masao , Kishi Hisao , Hamada Nozomu
Published: July 2007

One method for realizing a rational transfer function as a lattice digital filter is the procedure of Gray et al. using tap coefficient devices. Use of these devices should be avoided from the viewpoint of minimizing the number of multipliers. We have derived a discrimination condition and divided the structures into two classes; those realizing the rational transfer functions with lattice structures only and those requiring tap coefficient structures. A method is proposed for constructing lattice digital filters based on the state‐variable procedure. This method is systematic and suited for computer‐based design. The analysis is also simple. In the case of a general nth order filter it is shown that the coefficient sensitivity is low and a zero‐input limit cycle never occurs in complement truncation.
Method of random image systhesis by means of computer
Authors: Yoshida Yasuo , Ogura Hisanao , Sakura Yasuo
Published: July 2007

For fundamental research on image filtering, spectral estimation, identification, coding etc., it is beneficial to use a digital computer to generate a random image satisfying a given statistical property. The present paper defines random image as a random field satisfying a stochastic difference equation. The image is linearly syhthesized from a white‐noise field, namely, a series of independent random numbers. In terms of the 2‐dimensional prediction theory a detailed method to determine the 2‐dimensional autoregressive representation for the random field is given. Next, a hybrid method is given which uses Fourier transform in one dimension and 1‐dimensional prediction theory in the other dimension. The method of Green function is given for a special application, and a method which uses 2‐dimensional Fourier transform is described briefly. A concrete calculation is given using the cross‐type partial difference equation for the random field with an isotropic spectrum. Comparison of these four methods shows that there is little difference in the number of multiplications in the processing. However, the first method aids in generation of a large image by a computer with small memory.
Multi‐source‐sink pairs connection in a network and its heuristic algorithm
Authors: Onaga Kenji , Arimoto Atsushi , Kishimoto Kazuo
Published: July 2007

The problem of providing the required numbers ri of paths between specified q pairs of sources si and sinks ti (i = 1, 2,…, q) in a graph with edges having capacities which limit the numbers of their usages is called the realization problem of multi‐source‐sink pair connection in a network. Since this is an NP‐hard problem there are no suitable heuristic algorithms to solve it; however, it has a wide range of applications. This paper presents a heuristic algorithm based on Onaga's necessary and sufficient condition (called supply‐consumption inequality). Its effectiveness is examined by measuring its speed and accuracy with computational experiments. The connection time per a connection was proportional to the number of nodes of a graph (≦ 132) and accuracy was more than 96%.
Microwave endless phase shifter using dual‐gate FET
Authors: Ichikawa Hirohumi , Komaki Shozo
Published: July 2007

Endless phase shifters in which phase angles up to 360° can be endlessly varied are required in such areas as space diversity. Conventional endless phase shifters are large in size because they employ waveguides. To make these phase shifters in an MIC form, this paper adopts a method in which the input signal is divided into two with a 90° phase difference and then vector‐combined with appropriate amplitude ratios. To reduce the loss caused by an MIC, we use the dual‐gate GaAs MESFET as an active element. Realization of an FET endless phase shifter requires a dual‐gate FET amplitude adjustment circuit with a small amount of phase shift for a second gate bias. A method of optimizing the second gate terminating impedance to minimize the phase shift has been experimentally studied, although no theoretical analysis is available to date. In this paper, we analyze an equivalent circuit including the bias dependence of the circuit parameters of the FET and numerically compute the amplitude and phase of a dual‐gate FET. The results are compared with those of experiments. It is found that a theoretical design of the second gate terminating impedance is possible. Finally, the results for a fabricated FET endless phase shifter are described.
A general theory of the raman‐type free‐electron laser
Authors: Shiozawa Toshiyuki
Published: July 2007

A theoretical consideration is given for the stimulated Raman scattering by a relativistic electron beam uniformly magnetized with finite magnitude in the direction of its motion, assuming an intense electromagnetic wave for the pumping source. With the aid of analytical and numerical approaches, special attention is paid to the behavior of the scattered wave in the vicinity of electron cyclotron resonance. The interesting results obtained by the cyclotron resonance are summarized as follows. First, according to the conditions imposed on the pump wave, the scattered wave becomes either the electromagnetic wave mode or the electron cyclotron wave mode, or it is not excited. In addition, in the presence of a finite static magnetic field, the spatial growth rate for the electromagnetic scattered wave takes a maximum value for a particular set of various parameters, and the maximum growth rate becomes one order of magnitude or more (about 20 times in the specific numerical examples illustrated) as large as the growth rate for the case with no static magnetic field applied.
Millimeter wave video detection using pb thin film microbridge josephson junction
Authors: Yoshimori Shigeru , Kawamura Mitsuo
Published: July 2007

An experiment in video signal detection at 70 GHz was conducted with a Pb micro‐bridge prepared by electron‐beam exposure and the lift‐off method. It was found that for the dc Josephson effect the external noise is dominant over the internal noise of the specimen and that the equivalent noise becomes large near the critical temperature. The response to 100 kHz amplitude‐modulated signals was found to be ten times more rapid than that of the superconductor bolometer. Theoretically the maximum responsivity is obtained near the first Shapiro step, which, however, does not give a stable bias; maximum responsivity was actually observed near the zeroth Shapiro step, where it exceeded 6.3 × 104 V/W. The responsivity was found to increase with increasing IcRn.
Circularity of the pitch of complex tones and its application
Authors: Member Kengo Ohgushi, Regular
Published: July 2007

Paired comparison experiments were performed for the pitch of complex tones composing the endless scale as proposed by Shepard and those of two kinds of complex tones which are obtained by modifying the spectrum structure of the former complex tones. The results were analyzed by the multidimensional scaling program by Kruskal. As a result, it is shown that the pitch of the one, which is one of the three fundamental psychological attributes of the tone, has the mixed one‐ and two‐dimensional property in the case of the above complex tones. The tendency in the pitch comparison greatly differed by individuals, which can be accounted for by considering that the emphasis of the two elements of the pitch, which are tone height and tonality, differs by individuals. Using complex tones composing endless scale over 7 intervals, a melody over 10 intervals could be composed in a natural way.
Appearance of spatial sine‐wave pattern by exposure time
Authors: Member Haruo Sakata, Regular
Published: July 2007

The appearance of the temporal step pattern of the spatial sine‐wave (frequency 1.2 cpd) confirmed that the visual information pathways consist of two systems with different time response (they are assumed to be spatial and temporal dominant systems). In the foveal vision, the sensitivity shows a peak of about 50 ms exposure time. On the other hand, in the peripheral vision, the sensitivity reaches a peak of about 64 ms exposure time and shows a recess around 110 ms. These results at least indicate that there are two parallel pathways of difference temporal frequency bandwidths at the retinal periphery.
Bilevel rendition method for documents including gray‐scale and bilevel image
Authors: Tetsutani Nobuji , Ochi Hiroshi
Published: July 2007

The demand of facsimile transmission of printed matter as well as photographs is becoming strong daily as the variety of information is increasing. The disadvantage of the previous methods is that the character quality is deteriorated because in the case of artificial half‐tone reproduction using black and white recording, the resolution is sacrificed and tonal reproduction is performed. In this paper, a method to solve this problem is reported in which each block consisting of multiple picture elements is distinguished as bilevel region or gray‐scale region, and the processing suitable to each region is performed. This paper also describes the results of computer simulation obtained by applying this method to reproduce the characters and photographs. Moreover, the case of gray‐scale region lying inside the character region is discussed and it is shown that a simple region correction method is very effective.
Decrease in induced voltage on buried coaxial cable due to direct lightning stroke by earthing of metallic sheath
Authors: Member Toshiharu Nagano, Regular
Published: July 2007

When a direct lightning stroke hits a cable in which the metallic sheath is insulated from ground a high voltage is induced between the metallic sheath and the cable core and this may result in multiple insulation breakdowns in the cable and associated equipment. Compared to the case in which the sheath is in direct contact with the ground, attenuation of the lightning current in the cable is relatively small and it has been found that this is the reason for the low attenuation of the distributed electromotive force in the circuit formed by the core and the metallic sheath. If the metallic sheath is grounded to cause a distributed flow of lightning current into the earth, attenuation of the sheath current can be greatly increased and it can be expected that the induced voltage will be lowered, reducing the failure rate. Using the inverse Laplace transformation, the sheath current and induced voltage are computed for the case where the coaxial cable is grounded at equal intervals in a repeater section. It is found that grounding at 450‐m intervals results in induced voltage between the inner and outer conductors of the coaxial pair which is about 60% of the voltage for grounding at 3600 m intervals and the failure rate is reduced to about one‐fourth. This method permits accurate determination of the crest value of the inflowing current which will not cause insulation breakdown failure in the cable and permits us to devise lightning countermeasures which will hold the failure occurrence rate to allowable limits.
Appearance of short‐exposure colorlight–two successive colors and single color
Authors: Member Haruo Sakata, Regular
Published: July 2007

When comparing the three primary colors red, green and blue of equal luminance, the perceptual latency of blue is proved to be longer than that of red and green. Also, when two of the three primary colors are presented successively, the resultant color appears close to the second. This latter phenomenon suggests the presence of a temporal masking effect in the color mechanism. From these two phenomena, the fact that light from dark conditions of cyan and magenta presented for a short, rather than long, time appears close to blue because the perceptual latency of blue is longer compared to the other two. This is reasonably attributable to the color masking effect.
Analysis of probabilistic behavior of the system with nonregeneration points interpreted as Petri net by Markov renewal processes
Authors: Sugasawa Yoshio , Murata Koichi , Kurabayashi Yoshio
Published: July 2007

A Petri net is a system in which a meaning of simple interpretation is assigned to a set of signals. Petri nets can provide a particularly effective means of modeling a parallel operation. One of the advantages to be derived by modeling a system with a Petri net is the establishment of relationships between certain net structures and dynamic behavior. We begin by introducing a simple semaphore system interpreted as a Petri net. At the occurrence of a transition, the system states can be classified into regeneration points and nonregeneration points. Limiting probabilities of the system behavior are derived by applying a Markov renewal process. Finally, the time‐ratio concept is introduced and system deadlock is studied by analyzing the realtion between the change‐of‐time ratio and the limiting probability.
Complex bases in active CR networks and their relations with the network excitation
Authors: Ozawa Takao , Itoh Hiroshi
Published: July 2007

A complex basis can be defined for a set X of variables, such as branch currents and voltages (excluding the exciting currents and voltages), of a linear lumped‐constant network in the sinusoidal steady state. If a subset Xβ of X satisfies the condition that any variable in X – Xβ can be expressed as a linear combination of variables in Xβ with constant (not including the frequency) coefficients, then Xβ is called a complex basis of X. This paper derives general graph‐theoretical expressions for complex bases of the set of branch voltages and the set of modified branch voltages (= capacitor voltages x j, and/or resistor voltages) of an active CR network which satisfies certain conditions. The expressions derived have the same form as that in the case of a passive CR network. Second, the independence of the modified branch voltages which are obtained by varying both the phasor‐values (= effective values and phases) and the frequency of the excitation, is discussed. Let Xβ(k) be the vector of complex basis variables obtained by the kth excitation and let Xβ = [Xβ(1) ‐Xβ(k) ‐ Xβ(±) ] be the matrix obtained by A excitation. Then it is shown that there always exist some excitations which make Xβ regular. Finally, excitations which make Xβ regultvr can be actually specified, if the network satisfies certain conditions.

Acknowledgements. This research was partly supported by the Grant‐in‐Aid for Scientific Research by the Ministry of Education, Science and Culture of Japan, under Grant General Research (C) 58550232 (1983).
Coded octal PSK system performance disturbed by imperfect recovered phase reference
Authors: Fujino Tadashi , Umeda Yoshiaki , Yamazaki Eizo
Published: July 2007

There have been various investigations on the PSK modulation technique which is encoded by a convolutional code. For the bandwidth constrained transmission, such as satellite communications, it is important to hold a high information transmission rate. From this viewpoint, the coded 8‐phase PSK (8PSK) system seems advantageous.

This paper investigates the coded 8PSK system performance using the theoretical analysis and computer simulation when disturbed by the recovered carrier phase error and jitter. The results obtained here should be useful for coded PSK modem design.
Fault diagnosis of compartmental systems
Authors: Ohta Yoshito , Maeda Hajime , Kodama Shinzo , Itoh Takafumi
Published: July 2007

This paper investigates the fault diagnosis problems of compartmental systems from the viewpoint of linear algebra and graph theory. A system is considered faulty if a part of the system parameters (rate constants) takes an abnormal value. The problems of whether or not one can detect faults (fault detectability) and whether or not one can distinguish different faults (distinguishability) through observation of steady states are discussed. First, it is shown that the difference between the value of an observation vector for a faulty system and that for the normal system lies in a linear subspace corresponding to the fault, and a specific subspace is given. According to which linear subspace the difference in the observation vector belongs, a fault is detected and distinguished. Next, it is shown that conditions for fault detectability and distinguishability can be represented by using the dimension of the linear subspace corresponding to the fault and that an equivalent representation can be given in terms of the rank condition of a certain matrix. Finally, as the main result of this paper a representation is given for the distinguishability conditions on a compartment graph. In particular, when the number of the rate constants taking an abnormal value is at most one, these conditions can be replaced by directed path conditions which can be tested easily.
Tri‐reflector antennas with no cross‐polarized component
Authors: Urasaki Shuji , Makino Shigeru , Katagi Takashi
Published: July 2007

Since offset antennas have good wide angle characteristics, they are used frequently for ground stations in microwave communications‐ However, when the frequency reuse is considered via two orthogonal polarizations, the cross‐polarization components generated on the reflector surface create a problem. A method was reported in which the cross‐polarization components are cancelled in the geometric optics sense in the offset Casegrainian and Gregorian systems. In such a method, the degree of freedom in design is not large. For instance, the inclination of the axis of the conical horn used as the primary radiator is restricted. This paper studies tri‐reflector antennas in which the degree of freedom is larger. The geometrical condition for eliminating the cross polarization is derived and the shape of the reflector system satisfying the condition is found. To confirm the theoretical results, an antenna has been constructed. The cross‐polarization components are less than about ‐30 dB and hence the validity of the theory has been confirmed.
Physical considerations on multimode oscillations using the probability density
Authors: Takase Fuyuto , Kuramitsu Masami
Published: July 2007

In an oscillator with multiple degrees of freedom using one active element, stable multimode oscillation is produced sometimes while only single‐mode oscillation is produced at other times, depending on characteristics of the active element. To account for this difference, the generation mechanism of multimode oscillation is discussed. First, the averaging procedure in time in the averaged potential method is represented as an expectation in terms of the probability density function of the voltage impressed on the active element. Using this expression, the probability density minimizing the averaged potential, i.e., the oscillation waveform, can be determined for the given element characteristics. Thus, the generation mechanism for multimode oscillation is described and the relation of the element characteristics to the conditions for the single‐mode or double‐mode oscillations can be presented. It is especially hoped that by using suitable element characteristics, a double‐mode oscillation can be produced with unequal amplitudes not presently known. Furthermore, several conclusions can be made with respect to general properties such as the fact that the double‐mode oscillation cannot be produced using only one active element with soft‐excitation properties.
Design of ARMA digital filters by simultaneous specification of magnitude and group‐delay response
Authors: Kunimoto Toshifumi , Aoki Yoshinao
Published: July 2007

A method to design ARMA digital filters is proposed in which simultaneous specifications of magnitude and group‐delay are used. The properties of rational transfer function of z, and unique relation of magnitude and group‐delay response of minimum/maximum phase transfer function are presented. A design procedure is described based on these characteristics. The method consists of the Levinson‐Durbin algorithm and fast Fourier transform, which makes it very efficient in obtaining a recursive filter that has arbitrary magnitude and group‐delay responses.

An example is illustrated for comparison with group‐delay compensation.
On products of two‐dimensional linear recurring arrays
Authors: Sakata Shojiro
Published: July 2007

The two‐dimensional linear recurring array over a finite field is one of the important subjects of study in error‐correcting codes and in discrete image models. In order to derive arrays or codes of a wider class from arrays or codes belonging to a class, not only linear operations such as sum, scalar product and shift, but also their combination with a fundamental nonlinear operation (component‐wise product) can be used. A theoretical investigation has been made of the algebraic properties of the product of one‐dimensional linear recurring arrays. The result of the studies has the practical implication that a direct‐product code of a cyclic code can be constructed with fewer shift‐register stages, using the product in the sense of this paper. This paper is to extend the fundamental properties of the product of one‐dimensional linear recurring arrays to the two‐dimensional case. The paper mainly discusses how the characteristic ideal I of the product G(I) = G(Ii) G(l2) can be determined for the additive groups G(Il) and G(I2) for the two‐dimensional linear recurring arrays defined by the polynomial ideals Ii and I2, respectively.
Simple OHP equipment for demonstrating centrifugal spherical waves and group of minute articles by using moiré and reversal moiré and their evaluation
Authors: Kitagaki Ikuo
Published: July 2007

This paper describes simple OHP equipment as an aid in the teaching of physics, for example, electromagnetics by demonstrating centrifugal spherical waves and a group of minute articles radially progressing. A Moiré pattern is produced by using two grated transparencies having certain lattices, one fixed, and the other rotated. In this paper, rotating type Moiré patterns are used since they are easy to operate. Each lattice is designed as a function of the propagation velocity of each phenomenon to be demonstrated. The model of the movements of a group of minute articles is used for the divergence in a vector analysis. A reversal Moiré is used for this model. This paper discusses the method of designing the grated transparencies required for these models. Another model for demonstrating the electric force around a dipole is described, formed by overlapping two identical transparencies in a slightly shifted position. It is proven in this paper that this overlapped pattern agrees with the pattern of an electric field formed by a set of parallel lines charged positively and negatively, respectively, and with a homogeneous density. The responses of students to this equipment are analyzed via factor analysis, and the factor axis representing “idea” gains a relatively high mark.
Optimum capacity‐flow assignment problems with respect to fairness in loop networks
Authors: Iwakuma Yoshaki , Tanno Kuninobu , Nakamura Tadao
Published: July 2007

Conventionally, the problem of capacity‐flow assignment in packet switching computer networks has been considered mainly for the purpose of improving the network performance and the effective usage of the resources in the networks. The problem of the fair allocation of the network resources to each user (fairness) has been investigated little. Because one of the most important purposes of the computer network is that a plural number of users can use the network resources which are arranged dispersively in the network, we must make sufficient study of fairness in the problem of the flow assignment of the packet and the problem of the distribution of the line capacity. However, no clear definition of the fair allocation has been proposed to dare. In this paper, we adopt the “power” (function) as the performance measure and discuss the problem of the network capacity‐flow assignment in which maximized network. power ensures effective usage of networks, and equalized power for each user realizes the fairness. The results of this study provide a new guideline to solve the problem of distributing the resources effectively and fairly. The method in this paper can be discussed generally without limitation of the network topology. However, since the concrete numerical calculation is so complicated, we take loop networks for the object of the analysis.
ϵ‐Kalman filter—a method of signal estimation considering sudden changes of signals
Authors: Arakawa Kaoru , Harashima Hiroshi , Miyakawa Hiroshi
Published: July 2007

A digital filter is developed to estimate signals containing discontinuities from observations contaminated with low‐amplitude white noise. Called an ϵ‐Kalman filter, this is a Kalman filter combined with a nonlinear function. It is very effective for signals with known statistical properties. Principles of operation and realization of the filter are discussed. It is compared with another nonlinear filter called an ϵ‐filter also proposed by the authors. Results 01. computer simulations are shown to demonstrate the effectiveness of the new filter. Pictorial examples are also provided.
Clock path phase errors
Authors: Kihara Masami , Takama Tohru , Makino Masatoshi
Published: July 2007

This paper aims at the total design of synchronizing clock phase quality in a master‐slave synchronization network and studies the clock path phase errors. In master‐slave synchronization, reference clock distribution paths are a major source of phase errors. It is useful to examine the phase errors using Time Interval Error (TIE), specified in units of time. In this paper, the TIE of clock paths containing multiplexers, digital transmission lines and digital synchronous terminals is analyzed. Then measurements taken for multiplexers are presented by varying a stuffing ratio. Field data taken for a 7‐link clock path, the longest effective link path in Japan, shows that in practice a TIE of less than 100 ns over a 102 – 103 s measurement period is measured, which agrees well with theoretical data.
Approximation of multivariable linear systems by lower‐order models
Authors: Maekawa Sadao , Hinamoto Takao , Nakamura Yoshinari
Published: July 2007

This paper is concerned with the rational approximation of multivariable time‐invariant discrete‐time linear dynamical systems. An efficient method is developed for approximating given matrix Markov parameters (impulse response) by a low‐order rational function. This is a generalization of the approximation theory reported by Mullis and Roberts, and obtainable by extending their technique for single‐input single‐output systems to multiinput multi‐output case. The parameters of a rational function can be obtained by solving linear equations by means of a recursive algorithm. In addition, the stability of the approximating rational function is always ensured.
Performance of spread spectrum synchronous access communication system by orthogonal sequences
Authors: Zhu Jinkang , Nomura Tamiya , Yamada Takahiro
Published: July 2007

In conventional spread spectrum communication systems characterized by asynchronous multiple access SSRA (spread spectrum random access), interchannel interference is not zero and consequently the number of simultaneously communicable channels is small and the frequency utilization efficiency is low. The near‐far problem is also important. For performance improvement SSSA (spread spectrum synchronous access) systems with orthogonal sequences have been proposed. This paper discusses performance of an SSSA communication system which is based on the use of a set of orthogonal sequences formed by adding +1 to each of the M sequences. Because interference does not exist under the condition of perfect synchronism between channels, it may be expected that the multiple access capability is improved, the constraints of the nearfar problem are loosened, and the system will be immune to jamming. The performance in the absence of synchronism between channels and with imperfect demodulation of the spread code is studied by theoretical analysis and simulation.
Yagi‐uda array antenna composed of twin‐delta loops
Authors: Tou Shigefumi , Tsukiji Takehiko
Published: July 2007

When two regular triangular loops with peripheral lengths which are approximately equal to the wavelength are placed on a plane and fed in parallel to form an antenna, it acquires high gain and wide bandwidth. The overall properties of this antenna can be modified by changing the geometry of the loops. We propose a Yagi‐Uda antenna consisting of these triangular elements which has high gain and wide bandwidth with a small number of loops. Some numerical results when two or three loops are used are obtained by means of the moment method based on the Hallen integral equations, and the results are compared with experimental results. With a 2‐element array antenna consisting of a radiator and a reflector, the gain variation is small over an octave frequency range (the absolute gain is as high as 9.6 dB) and the impedance is also wideband. A high‐gain, wideband operation will be achieved with a small number of elements when combined with conventional dipole directors.
Parallel queues with common service process and their input controls
Authors: Fukuda Aki'Ra , Sato Shoji , Mukumoto Kaiji
Published: July 2007

In the parallel queue with common service process, there are m independent arrival processes to m waiting spaces. When customers are waiting in all of the waiting areas, the server accepts a customer from each waiting space, and the service is made simultaneously to the m customers. This paper discusses the fundamental properties of such a system, presenting the approximate analysis, qualitative interpretations, and simulation. It has been well known that this kind of system is essentially unstable for any load. This paper presents first the qualitative interpretation for the instability and discusses its relation to the cointossing. Then several heuristic input control schemes are proposed. Their usefulness, control characteristics and the effect of the dalay in the control path are discussed. It is shown as a result that the system can easily be stabilized by a weak input control, and can be stabilized for the case of m =2, even if only one of the queues is controlled. It is indicated also that a too strong control has an adverse effect if there exists a delay in the control path. Several additional observations are made.
Transient probability of complete system failure for an electronic switching system
Authors: Masuda Kohsaku
Published: July 2007

The redundant construction of a switching system, such as n‐tuple, n active plus m standby and n‐tuple plus m standby systems, can be represented by the birth‐death process model, which is a finite‐order Markov process. It is shown that the transient probability for the system failure is given by Pn(t) Pn[1 – exp(– 1/2 {1/TnP t + 1/Tn‐δ)Pn (t – δ)}], where Pn is the steady‐state probability that the redundant structure is in system failure, and P =Un/(Tn + Un); Tn and Pn are the mean times in which the system arrives at the system failure state n from the normal state 0 for the first time, and the time to arrive at the state 0 from the state n, respectively. They are equal to M.T.T.F (Mean Time to Failure) and M.T.T.R. (Mean Time to Repair), respectively; δ is a constant which is determined separately, and is given by =(n – 1) 1/μ where 1/μ is the mean repair time of the unit. It was verified that the approximation is close to the transient solution of the differential equation representing the actual situation. The result is then applied to the analysis of the switching system to derive the unavailability Pn(t) of various redundant structures.
Consideration of characteristics of multipacket transmission in erroneous channel
Authors: Komatsu Masaharu
Published: July 2007

In multipacket transmission, one or more packets is inserted in one frame. Thus, the overhead per packet is smaller than that of single‐packet transmission. However, a larger frame length suggests a higher error probability, a larger packet retransmission rate, and a larger transmission delay. In this paper, considering packet retransmission by error detection, we analyze two basic multipacket transmission schemes, gating‐service‐type and exhaustive‐service‐type, and the ordinary single‐packet transmission scheme. Also, from numerical examples, it is shown that the gating‐service‐type multi‐packet transmission scheme is superior to the other two schemes both in throughput and packet delay characteristics.
Realization of grounded/ungrounded and equal/unequal‐valued switched‐resistors
Authors: Fukai Sumio , Tsukahara Masahisa , Ishikawa Hirobumi
Published: July 2007

As a method for realizing equivalent resistance useful for monolithic integrated circuits, a switched‐resistor circuit has been proposed. In this method, the linear resistance region of the FET is used, and hence the device works as a continuous time system. However, the proposed circuit is only for the case of realizing a single resistor. There does not appear to be any proposals for realization of several resistors. In this paper, from the viewpoint of the number of elements, a circuit configuration is proposed in which grounded/ungrounded and equal/unequal‐valued resistors are realized with a small number of elements. The circuit configuration is based on the single pretune circuit in a pretuned structure used in a time domain multiplex. A switching circuit controlled by a multiphase clock is used. The new pretune circuit here is suited for realization of the case in which the grounded and ungrounded resistors coexist. Two pretune circuits and two switching circuits are presented. Two cases are shown for realization of unequal‐valued resistors. As an application, a third‐order high‐pass filter with three switched resistors is demonstrated.
Multibeam array antenna for data relay satellite
Authors: Teshirogi Tasuku , Chujo Wataru , Akaishi Akira , Hirose Haruzo
Published: July 2007

As the use of space expands, the demand for data relay systems between satellites used for real time data transmission between the ground station and a satellite has increased. This paper proposes a data relay multiple‐access system between satellites which is suited for a relatively small number of users in Japan. The paper also describes the 19‐beam multibeam array antenna developed for this system. Compared to NASA's AGIPA system, the present on‐board multibeam system has a number of advantages: effective use of frequency and power; simplification; and cost effectiveness of the ground station if the number of user satellites is small. Next, a multibeam antenna system suited for this system is studied. It is found that the multibeam array is suited in the case where many beams are formed with a relatively small aperture. The configuration and design method are described. As individual elements, a newly developed broadband microstrip array and a small beam‐forming circuit with a good beam‐forming capability are described. Based on these devices, a 19‐element array antenna with 19 multibeams and one scanning beam is developed. Its technical possibility is proven as a satellite‐borne antenna.
Some encryption networks and an evaluation function for cryptosystems
Authors: Ikeno Nobuichi
Published: July 2007

This paper considers a problem of realizing encryption circuits in the form of the cascade connection of basic circuits and finds a very simple basic circuit which enables an arbitrary encryption. A simple circuit form in the minimum stage circuits is proposed. Next, a quantity is defined which seems to be a criterion for measuring the strength of encryption and not only are several of its properties shown, but also how this quantity appears for a few crypto‐systems including the cryptosystem based on the forementioned circuit form.
Design of sound source with fresnel‐zone pattern and its field analysis
Authors: Hidaka Ryo , Kikuchi Tsuneo , Moriizumi Toyosaka , Shiokawa Showko , Nomura Tooru
Published: July 2007

When an interdigital transducer (IDT) is loaded with a liquid, an acoustic beam can be excited in the liquid. To focus this acoustic wave in the liquid, the authors have used an IDT that is divided in a Fresnel zone type in the direction of the electrode aperture. From a theoretical calculation of the focused acoustic field generated by the Fresnel zone IDT, it is found that the point of maximum sound pressure is closer to the electrode than the designed focal point. To find the cause of this discrepancy, the acoustic field excited by the Fresnel zone source is analyzed. It is found that a modification in the design model of Fresnel zone IDT's is needed due to the difference between the two‐ and three‐dimensional fields. A new optimum design method is proposed in which the focal point obtained from field analysis and that obtained from the electrode design model coincide.
A telephone network overload control scheme using adaptive control
Authors: Satake Yasuhiro
Published: July 2007

This paper proposes an input regulation overload control scheme of a telephone network using a self‐tuning regulator as one of the adaptive controls. The exchange node is modeled by a simple queue and servers and input traffic is regulated by a switch according to the control signal. In this scheme, dynamic characteristics are estimated using control signals and state variables of the system. The control signal is determined based on these characteristics so that it minimizes the mean square of the difference between the state variable and the control reference which prevents the throughput deterioration. Simulation studies show that the proposed control scheme can maintain the throughput even under extreme overload traffic and large control delay.
Analysis of error propagation and design of filter cutoff frequency in a quantized feedback dc‐restoration system
Authors: Yamaguchi Haruo
Published: July 2007

In the regenerative repeater in digital transmission, the low‐frequency component of the transmitted pulse is cut off by the coupling circuits at the input and the output. However, by applying the quantized feedback dc‐restoration circuit in the repeater the digital regenerative transmission with low dc‐balance transmission code can be achieved. In the quantized feedback system, the component lost in the low‐frequency cutoff characteristics of the transmission system is restored by feeding back the low‐frequency component of the pulse regenerated in the repeater to the decision circuit input. Because of this mechanism, however, an error propagation occurs where an error component is fed back to produce a distortion and to enlarge the error, when a decision error is produced in the repeater. This paper derives the state‐transition diagram which approximates the error propagation. By the analysis of the state‐transition diagram, the relation between the filter cutoff frequency and the error propagation characteristics is determined. Furthermore, it is shown by a simulation experiment that the result of the analysis is a good approximation to the error propagation. Based on these results, a design method is presented for the cutoff frequencies of the forward and the feedback low‐pass filters in the quantized feedback system.
Evaluation of transient intermodulation distortion in operational amplifiers
Authors: Kitamori Susumu
Published: July 2007

When a transient signal with rapid rising is applied to an operational amplifier, and the input amplitude is increased, the output is influenced by the slew‐rate. If multiple signals are amplified simultaneously by such an amplifier, transient intermodulation distortion arises in the output. In this paper, first, the transient intermodulation distortion rate is measured for the variation of input voltage to a general‐purpose operational amplifier when a rectangular wave or the convolution of a triangular wave and sine wave are used as input signals. Next, as a method for estimating quantitatively the influence of this transient intermodulation distortion over tone quality, we obtain a d' value by applying signal detection theory to experimental results on the audibility. Then, by determining that transient intermodulation, distortion can be discriminated on the sense continuous body when d' =1, and by obtaining the value of the transient intermodulation distortion rate corresponding to the case, we estimate transient intermodulation distortion in an operational amplifier.
Height estimation of a cruising aircraft via a radar for air traffic control
Authors: Nagaoka Sakae
Published: July 2007

Information on the three‐dimensional position of aircraft is necessary for air traffic control. The current height information of aircraft does not always show a geometric altitude since it is based on an onboard barometric altimetry system. Therefore, a method for monitoring the height of aircraft independently of barometric sensors is desirable.

This paper describes a method of height estimation for an aircraft flying at a constant speed, level and straight using a radar for air traffic control currently in use or to be used in the near future, and presents the results of consideration on the estimation accuracy of the proposed method. In this method, the data taken by approximately ten times the scans by a fan beam are used for height estimation based on the curve which fits under the assumptions that the data acquisition area is nearly 10 NM the distance from the antenna.

Height estimation accuracy by this method is evaluated by a computer simulation. The results show that height estimation accuracy depends strongly on the data acquisition area (that is, the geometrical relation between aircraft and the radar sensor), and the influence of range measurement accuracy is predominant at a cruising altitude of 29,000 ft (= 8.84 km). The height estimation accuracy is estimated to be approximately 100 m (1s̀) under the best conditions assuming that the standard deviation of range measurement errors is 30 m (1s̀) and that of azimuth errors is 0.06 deg (1s̀).
Electromagnetic scattering by a perfectly conducting rectangular cylinder located near the conducting plane
Authors: Ogura Takao , Kozaki Shogo
Published: July 2007

The scattering problem is analyzed in the case where an electromagnetic wave is incident on a perfectly conducting rectangular cylinder located near the conducting plane. Since it is difficult to solve this problem directly as the boundary value problem, the problem is replaced with that of scattering by two conducting rectangular cylinders by means of the method of electrical image. The analysis is based on the point matching method and the amount of computation is reduced by reducing the number of simultaneous equations derived from the boundary conditions into one‐half by using the symmetry of the electromagnetic field. As the numerical examples, the near field and the scattering patterns are presented which have not been reported often. Numerical results are compared for the perfectly conducting circular cylinder located near the conducting plane with those of the rectangular cylinder. To confirm the theory, a model experiment is conducted at microwave frequencies so that reliability of the theory is tested.
A proposal on digital watermark in document image communication and its application to realizing a signature
Authors: Komatsu Naohisa , Tominaga Hideyoshi
Published: July 2007

With the advance of telematic technology, increasing document image information utilized in the state of soft copy is expected. In these situations, copies of obtained document image information are made illegally with ease, and hence the validity authentication of the information itself and its provider becomes more necessary. Since document image information to be authenticated exists in a form which can be read at an unidentified number of receiver terminals, the realization of an authentication scheme where document image and signature are combined is necessary. This is characteristic of document image information including nature pictures and photographs.

This paper proposes a new concept of signature, which is called “digital watermark” for document image communication. A digital watermark is the coding scheme in which secret information is embedded into a document image similar to a watermark. Image coding schemes already proposed are available to realize a digital watermark. We present a method of obtaining a digital watermark using a well‐known predictive coding algorithm. Also, we define a criterion for security and show to what extent the digital signature is safe using simulation results, where two or three illegal actions are considered.
An optimum design of alternative routing system with trunk‐reservation scheme
Authors: Akimaru Haruo , Katada Hironori , Okuda Takashi
Published: July 2007

The trunk‐reservation scheme is employed to specify the individual call loss in the alternative routing system. The numerical solution of the state equation and the simulation has been used traditionally for the optimum design of such a system. This paper presents the optimum (in the sense of the minimum cost) design of the alternative routing system with the trunk‐reservation scheme, using the approximate expression for the individual call loss and its derivatives. A method is presented also to obtain the optimum integer number of trunks. By an example, it is shown that the presented method of the optimum design can reduce the computation time drastically and provides a good approximation compared with the past methods by state equation or simulation.
Electromagnetic wave propagation in two‐dimensional impedance tunnels with modified multicross‐junctions
Authors: Matsunaga Toshiaki , Uchida Kazunori , Noda Takeaki
Published: July 2007

As a model for the electromagnetic wave propagation in a tunnel‐shaped structure with branches and bends such as an underground shopping center and a street lined with buildings, a two‐dimensional tunnel with modified multicross junctions is studied both theoretically and experimentally for wave propagation. The basis of the theoretical analysis is to neglect the higher‐order multiple scattering effect and to consider the field as the cascaded connection of the results of the modified single‐cross junction. As the boundary condition of the tunnel wall, the surface impedance approximation is employed. The present results can be applied to special tunnels made of cascaded connection of the modified cross, step and T. In the experiment, a microwave simulation is carried out for a tunnel model made of concrete. It is found that the numerical results of the electric field intensity in the tunnel agree well with the experimental results.