bluuebunny/crossref_metadata_2025 huggingface dataset:
Minimization of the number of links in three‐level hierarchical telecommunication networks
Authors: Mase Kenichi
Published: July 2007

Minimizing the number of links (trunk groups) is important in reducing not only the equipment cost but also the operation and maintenance costs in a digital toll‐switching network. However, by minimizing the number of links in a digital toll‐switching network, obtaining an optimal area configuration is a problem. This is because the fixed idea that the area configuration of such a network is invariable is disregarded.

In this paper, the multiunits of a three‐level toll‐switching network are considered and factors determining the number of the links are modeled. Then it is shown that the number of links is minimized when the areas of upper‐ and lower‐level toll‐switching centers are constructed equally. In addition, conditions for an optimal area configuration that minimizes the number of links are shown by numerical examples for two‐level and three‐level networks of conditions that minimize the increase in the number of units of toll switches and more than two switch units of a toll‐switching center for ensuring reliability. As a result, it is shown that a three‐level network is advantageous compared with a two‐level network since the capacity of a toll switch is small and the traffic current tends to concentrate at a near distance.
Method of estimating the maximum radiated interference field of electronic equipment by using randomly assigned phase terms
Authors: Murakawa Kazuo , Kuwabara Nobuo
Published: July 2007

Using the electric field strength measurement value vicinal to electronic equipment set up in a factory, investigation was made by the experimental method stipulated by VCCI, that is, by both theory and experiment, estimating the maximum value of the electric field strength measured for the set‐up of electronic equipment at the test site by the 10‐m test method.

In the estimation method proposed, the electric field strength in the vicinity of electronic equipment is measured in cylindrical form, the phase of the measurement point is assigned by uniform random number and, employing the integral expression of electric field using these values, the maximum value of the electric field strength of the estimation surface is estimated.

In the investigation, even in the case of assigning phase by random numbers, it was found theoretically possible to estimate within 6‐dB accuracy the maximum value of the electric field strength of the estimation surface. Moreover, as a result of investigating the accuracy of the estimation method using a spherical dipole antenna as a radiation interference source, it was confirmed experimentally that the deviation between the estimated value and measurement value is roughly below 4 dB over a frequency of 100 MHz to 1 GHz.
Use of neural networks for the optimum frequency assignment problem
Authors: Kurokawa Takakazu , Kozuka Shigeki
Published: July 2007

When two satellites in close proximity to each other use the same frequency band, mutual signal interference is unavoidable. Especially, it is known in the FDMA communication system that the interference to each carrier and the total interference depends greatly on the carrier frequency assignment. At the present stage, where a large number of satellites have entered into operations, the assignment of the frequencies is becoming ever more important.

This paper aims at a high‐speed determination of the signal carrier assignment so that the signal interference is minimized and proposes a method of parallel solution using a Hopfield‐type neural network. In the proposed solution method, the given frequency band is segmented into n frequency bands and the assignment is derived by rearranging the segments using the two‐dimensional neural network array.

The following properties were revealed as a result of simulation. The optimal solution or a solution close to the optimal can be determined from a tremendous combination of possible solutions, while suppressing the explosive increase of the computational complexity with the increase of the problem size. The power to derive the solution depends on the carrier configuration.
Standardization aspects of B‐ISDN–‐technical issues in high‐speed data communications services deployment
Authors: Imai Kou Miyake Kazuo
Published: July 2007

This paper discusses issues in the research of B‐ISDN standardization being conducted by the CCITT and other institutions, the results of this research to date, and possible future studies. More specifically, it discusses the technology of deploying high‐speed data communications services for initial services.
Heterodyne optical detection/spatial tracking system using spatial field pattern matching between signal and local lights
Authors: Tsukamoto Katsutoshi , Morinaga Norihiko
Published: July 2007

The spatial tracking system controlling the directivity of the optical antenna determines the quality of communication in the ultradistance intersatellite optical communication system. The spatial tracking system using optical heterodyne detection has a high receiver sensitivity, being less susceptible to background light. This is the dominating factor for noise in cosmic space. In recent years, intensive studies have been made on this system hoping for the tracking performance with a higher accuracy than that obtained by the direct detection system.

This paper presents a principle of angular error detection which is different from the conventional system and proposes a new optical heterodyne/spatial tracking system based on that principle. The principle on which the proposed system is based is that the incoming angle of the signal light is tracked by utilizing the variation of the spatial matching to the local light due to the variation of the incoming angle of the signal light. Its feature is that the angle error can be detected using a single ordinary optical detector, not the quadrant optical detector.

A theoretical analysis of the noise equivalent angle (NEA) is presented. The optimal local light diffraction pattern is shown for the rectangular antenna aperture. The performance of the system is analyzed from the viewpoint of NEA, and the result is compared to the performance of the optical heterodyne detection/spatial tracking system using the quadrant optical detector.
A new design for program‐controlled voice switching circuits using a microprocessor
Authors: Oikawa Hiroshi , Makino Shoji , Nishino Masakazu , Yamamori Kazuhiko
Published: July 2007

The voice switching circuit (VS) is applied widely to various problems, including echo suppression and howling suppression in the communication equipment, realizing the magnified voice communication using microphones and loudspeakers. It is also applied frequently in recent years in combination with the echo canceller, in a form to complement the performance of the echo canceller.

Kato et al. [3] discussed in detail the operational performance and the design method when VS is realized by the analog circuit, and proposed the automatic loss switching VS (ALS), where the switching loss is reduced by automatically adapting to the change of the acoustic and side‐tone characteristics. In their method, however, ALS is constructed using only the analog circuit. This makes the design complicated and makes it difficult to reduce the switching loss compared to the present design. With this in mind, the goal here is to realize the ALS function by program control, using the microprocessor (μP). the following two program‐controlled VS with excellent voice communication functions are proposed.
Virtual path trace function and its mechanism for ATM transport networks
Authors: Matsunaga Haruhiko , Ueda Hiromi
Published: July 2007

To make the operation, administration, and maintenance (OAM) functions of virtual path (VP) in the ATM transport network efficient, the authors present a trace method which collects VP route configuration information automatically. This method enables rapid search of VP routes which are managed dynamically. Therefore, it becomes easy to operate and manage the accurate network configuration in ops.

In this paper, the requirements for the VP trace method are clarified and mechanisms for the VP trace method realization are presented. Then, the VP trace OAM cell format, the VP trace processing algorithms in each ATM network system, and the implementation of the required functions are discussed. Finally, the VP performance is evaluated.
Global motion compensation in video coding
Authors: Kamikura Kazuto , Watanabe Hiroshi
Published: July 2007

As a motion compensation method for video coding, a global motion estimation method is proposed that estimates and compensates general image motion caused by camera pan and zoom. By utilizing block displacement vectors derived from the widely utilized block‐matching method, global motion parameters are computed with a noniterative process requiring few multiply‐add operations. Parameters associated with pairs of blocks symmetrically located with respect to the center of the image are calculated, and the histogram of these parameters is then used to efficiently compute accurate motion values that depend on nothing but camera pan and zoom. A corresponding block‐by‐block ON/OFF control method is also proposed for the global motion compensation scheme. By utilizing these methods, a relatively simple and efficient coding technique with global motion estimation is realized.
Protocols to accommodate asynchronous transfer mode cells in satellite TDMA links
Authors: Ohta Atsushi , Okada Kazuyasu
Published: July 2007

To deyelop the broadband integrated services digital network (B‐ISDN) service on a national scale and to handle various media in a unified way economically from ‐ an early stage, it will be effective to construct a system combining the satellite link into the terrestrial communication network. the TDMA system is adequate as the transmission system in the satellite link in such a system which can contain efficiently users distributed over a country.

When the satellite TDMA link, which is a synchronous system, and the terrestrial network, based on the asynchronous transfer mode (ATM), are to be connected, the deterioration of the ATM transmission quality such as the cell delay variation, is a serious problem. Then there must be a compensation method for the delay variation which can cope with the asynchronous transfer. In such a transformation between ATM and TDMA, it is required that the maximum delay variation should be kept below the specified value, the burstiness of the transferred cell sequence should not be increased, and the satellite link with limited network resources should efficiently be utilized.

This paper assumes that the time‐stamp method, which is considered in the ground network, is applied to the satellite link as a method for the delay variation 38 compensation and summarizes the problems in the application. Then the cell‐numbering method is proposed and the performance is evaluated to solve the problems.
Differential detection for 16 amplitude/phase shift keying (16 dapsk) using viterbi algorithm
Authors: Nemoto Koji , Sasase Iwao
Published: July 2007

Recently, differentially encoded 16 amplitude/phase shift keying (16 DAPSK) has been investigated intensively for mobile radio applications. Since the bit error rate (BER) performance of differential detection (DD) is inferior to that of coherent detection (CD), multisymbol DD of 16 DAPSK has been proposed. However, as the observation interval of multisymbol DD is increased to improve the BER performance, computational complexity increases.

In this paper, the differential detection scheme of 16 DAPSK based on the maximum likelihood sequence estimation (MLSE) using Viterbi algorithm is proposed and the BER performance of the proposed scheme is investigated by computer simulation. It is shown that the BER performance of Viterbi‐decoding DD outperforms that of three‐symbol DD without increasing the computational complexity.
An autonomous provisioning algorithm of remote operation in asynchronous transfer mode networks
Authors: Tsuboi Toshinori , Kikuchi Katsuaki
Published: July 2007

To achieve efficient and highly reliable network operation requires a mechanism to monitor and control the states of remote terminals (nodes) automatically by the central operation system (OpS). This paper is an attempt to obtain such a mechanism. Operation and maintenance (OAM) cell is defined that contains the connection information for remote monitoring and the control path to be set. By successively transferring OAM cells according to the connection information, remote monitoring and control virtual paths (VPs) can be obtained autonomously.

Based on the proposed idea, this paper discusses the structure of the OAM cell, the functions to be provided in the cross‐connect system, and transmission algorithms for the OAM cell. The proposed system well utilizes the unique feature of the ATM cell. The cell routing information (VPI) is transferred within itself.
Development of experimental automatic dependent surveillance system and inflight performances
Authors: Ishide Akira , Fujita Mitsuhiro , Niimi Kenji , Matsuzaki Fumitaka , Yukawa Kiyoshi
Published: July 2007

The automatic dependent surveillance (ADS) system has been developed and tested through flight trials using INMARSAT satellites. ADS is a new surveillance system that uses a satellite datalink for aircraft in oceanic areas. Test results showed that the ADS transmission protocol is reliable and message losses are very few, the transmission delay for the R channel is about 3.4 s and that for the T channel is 15.6 s under fair link conditions. The latter should be reduced for additional improvement in surveillance capability in the future. It may increase due to degradation of link condition by aircraft attitude change.
Satellite channel assignment method with control of call‐loss probability for carriers with different transmission bandwidths under frequency‐division multiple access
Authors: Hayashi Masato , Takahata Fumio
Published: July 2007

In the satellite communication system with frequency‐division multiple access (FDMA), the efficient use of the frequency band is very important. This paper discusses the channel assignment method which can realize a high channel utilization for three kinds of information with different bandwidths while efficiently controlling the call loss probability.

As conventional methods, the orderly assignment method, which is known to realize a high channel utilization, as well as the separate assignment for each kind of call, where the odd effect is not produced, are considered. For the purpose of this study, the floating boundary assignment (FA) is considered, which is based on the orderly assignment and a new channel search algorithm so that the call loss probability can be controlled. The proposed method is compared to the conventional methods.

First, it is shown by the performance evaluation by simulation that the FA method can realize a high channel utilization and the call loss probability control. Using the satellite communication system based on the demand‐assignment scheme, the performance of the FA method is partially examined by experiment. By assuming a precise requirement for the call loss probability, the call loss probability control performance as well as the channel utilization are examined. The proposed FA method is shown to be useful through the comparison.
A delay lock loop using delay path cancellation for mobile communications
Authors: Takeuchi Makoto , Nakagawa Masao
Published: July 2007

Under multipath fading channels, the conventional delay lock loop (DLL) performance is degraded because of delay jitter caused by multipath signals. This error causes a large performance degradation of signal‐to‐noise ratio (SNR). It is necessary to reject the multipath error in order to improve the CDMA mobile communications performance.

This paper introduces a new tracking system which cancels the effect of the delayed paths. The proposed system consists of multi‐DLLs, an adaptive equalizer and a replica generator. This system generates a replica of the received signals by employing estimated values of the delay errors and the amplitude levels and removes the undesired signals from the received signal. The performance of this system is evaluated by computer simulations, showing a remarkable improvement of the delay jitter and a better performance of 3 dB at BER of 10−2.
Performance analysis of input and output queueing packet switch with multiple priority classes
Authors: Takemori Keisuke , Shiokawa Shigeki , Sasase Iwao
Published: July 2007

This paper proposes an N X N input‐output buffered switch model which switches several kinds of packets emphasizing the real‐time property as well as packets emphasizing the secure transmission. The model corresponds to the Poisson and Bernoulli traffic switching system. Such performances as the average system queueing delay and the loss probability for the packet emphasizing the real‐time transmission are analyzed. Nonpreemptive priority discipline is applied on the input side where the circuit configuration is relatively simple. On the output side, the first‐come/first‐served (FCFS) process is applied without considering the priority service.

In the proposed model, the output buffer size is assumed as finite and the input buffer size is assumed as infinite. For the two kinds of switching systems which serve the Poisson arrival packets and the Bernoulli arrival packets, respectively, the mean system queueing delay for the priority class is analyzed. For the case where the input buffer size is limited for the packet with a high priority emphasizing the real‐time transmission, the relation between the loss probability for the packet with a high priority and the sizes of the input and output buffers is investigated by a computer simulation for the case of two classes. The adequate input buffer size for the packet with a high priority is determined.
Circular patch antennas miniaturized by shorting posts
Authors: Kuga Nobuhiro , Arai Hiroyuki
Published: July 2007

As a small antenna for mobile communication, a circular patch antenna miniaturized with a shorting post is proposed. These shorting posts are placed near the feed post. The circular patch antenna miniaturized by offset feed is excited by a hybrid of the coaxial TM01 mode and the TM11 mode. Hence, the antenna has directivities in several polarization planes so that a low gain pattern not realizable with an antenna with a monopole mode is attained.

The theoretical analysis of the antenna is carried out by a cavity model in which an impedance boundary is assumed at the edge of the element. Since the conventional procedure cannot be applied to the coaxial TM01 mode that is the fundamental mode of the antenna, an approximate formulation based on the equivalent circuit containing the feed post and the shorting post as the current sources is proposed. It is confirmed that the numerical results of the input impedance and the experimental results agree well. From the numerical analysis, the modal amplitude characteristics of the magnetic current contributing the radiation and the resonant frequency characteristics of the antenna are discussed from the relationship to the feed method.
Radiation efficiency measurement of a small antenna using the wheeler method
Authors: Muramoto Mitsuru , Ishii Nozomu , Itoh Kiyohiko
Published: July 2007

The antennas for mobile communication handsets have become smaller in shape, which has degraded their electrical performance significantly. To obtain a small but high‐performance handset, it is important to increase the antenna efficiency. The important parameter for such a purpose is the radiation efficiency which can be measured easily by the Wheeler method. This method is carried out based on the assumption that the input power is equal to the power loss if the antenna is covered with a cap of a size on the order of a radian sphere. However, unless this assumption holds, the computed Wheeler efficiency does not give accurate radiation efficiency.

When the radiation efficiency is actually measured by the Wheeler method, the measured values often have a dip from the theoretical value. In this paper, the cap is approximated by wire grids and the Wheeler method is simulated on a computer. It is confirmed that the dip is not caused by the measurement method. It is shown that the cause derives from the invalidness of the presumption of the Wheeler method that the internal reactive electromagnetic field does not change when a cap is placed. It is shown also that the Wheeler method can be used sufficiently even if the size of the cap is larger than the radian sphere. The limit of application is studied.
Performance of limited‐state sequence estimation under land mobile frequency‐selective fading channels
Authors: Kamio Yukiyoshi
Published: July 2007

The frequency‐selective fading is one of the problems in the high‐speed transmission in land mobile communications. A solution is to use the Viterbi equalizer. When this method is applied to the highly efficient modulation system such as QPSK, however, the computational complexity increases rapidly with the increase of the delay time of the delayed wave to be compensated. This makes the instrumentation impractical.

This paper proposes a method in which the computational complexity is reduced drastically by the limited‐state sequence estimation. In the proposed method, limited‐state sequence estimation (Viterbi algorithm) is applied where two waves with the largest powers are selected based on the estimated impulse response. Based on the tentative decision obtained beforehand by a simple method, the effects of other waves are eliminated. The number of states is estimated considering only the selected two waves.

The performance of the proposed method is examined by a computer simulation. It is shown as a result that the range of compensation can be enlarged and the computational complexity can be reduced, compared to the conventional simplified method. In other words, the effectiveness of the proposed method is demonstrated.
Fast channel impulse response estimation scheme for adaptive maximum likelihood sequence estimation equalizer—proposal of variable‐gain least mean square algorithm
Authors: Denno Satoshi , Saito Yoichi
Published: July 2007

This paper discusses the channel estimation algorithm in the adaptive maximum likelihood sequence estimation (MLSE) and proposes the variable‐gain least square (VLMS) algorithm that can realize a fast acquisition by a simple configuration. When the sent code is a random sequence, VLMS is represented by a deterministic canonical equation based on the fact that a deterministic autocorrelation matrix for VLMS can be diagonalized.

It is shown that VLMS can be realized with nearly the same computational complexity as least‐mean square (LMS) algorithm. It is shown theoretically by analysis that VLMS can realize the same fast acquisition and tracking characteristics as those of the recursive least square (RLS) algorithm. An algorithm also is derived which is an extension of the basic idea of VLMS and can be used for the fractional MLSE equalizer. It is shown experimentally that the fractional MLSE equalizer with VLSE algorithm can compensate the performance deterioration due to the sampling phase error. In the two‐wave Rayleigh fading environment with faT = 4.0 × 10−4, the floor error can be suppressed below 10−4. It is shown also experimentally that the proposed equalizer has an excellent synchronization performance in which the initial acquisition can be completed in approximately six symbols.
Antenna factors of half‐wavelength dipole antennas with roberts balun
Authors: Kim Ki‐Chai , Tokumaru Shinobu
Published: July 2007

To use antenna factors most effectively in either EMI measurement or the reference antenna method, the antenna factor is more accurately derived than the conventionally obtained value when a half‐wave resonant dipole antenna with Roberts balun (ANSI C63.5 Specification) is placed on the ground plane. In the calculation, the antenna is treated as the boundary value problem of Maxwell's equations and is analyzed by the Galerkin moment method. The balun is treated using circuit theory based on power transmission mismatch. To confirm the validity of these theoretical calculations, the computed value of the antenna factor in free space is compared with the measured results by the standard site method and the standard antenna method. It is confirmed that the tendency of the numerical results agrees well with that of the measured values.
Measurements and analyses of multipath propagation structure for small‐cell digital mobile radio in hilly areas
Authors: Laksono Trisila Heru , Maeyama Toshiyuki , Kitano Yasushi , Ikegami Fumio
Published: July 2007

For research on characterization and reduction of the bit error rate in high‐speed digital mobile communication, the understanding of the multipath propagation structure is indispensable. In this research, a measurement system is developed in which the two sets of directive antennas and the delay time measurement method by TV video signals with a sharp pulse inserted are combined.

The multipath propagation structure is measured in detail in hilly small‐cell model areas. In addition to conspicuous reflections from the buildings and hills around the measurement course, the reflected waves from far away buildings and multiple (several times) reflected waves are observed. The power‐delay profiles and the nature of the delay spread of the multipath waves are analyzed so that the effect of the delayed multipath waves on the bit error rate in the digital transmission is found.
Magnetic layer design considerations for highly durable recording tape
Authors: Iijima Tetsuo , Hosokawa Shigefumi , Hiratsuka Hiroaki
Published: July 2007

Among magnetic recording tapes for such applications as mass storage systems, the antiabrasion properties of the magnetic layer along with storage life are major factors determining magnetic tape life. This paper examines the effect of magnetic layer structural parameters which affect durability and the signal‐to‐noise ratio. Several magnetic tape layer design conditions aimed at improving magnetic tape reliability and recording density are then presented. That is, in order to effect a highly durable binder structure, it is necessary to achieve appropriate mechanical characteristics (tensile strength ≥1 kg/mm2 and elongation at break ≥40%) by crosslinking a large‐matrix, high‐molecular weight polyurethane as well as carefully adjusting the balance of each additive. On the one hand, lapping treatment is effective in improving the SN ratio, with a decrease of up to two‐thirds in surface roughness possible. At the same time, it is found that magnetic pigment content is an important factor limiting durability and that it is a sensitive structural parameter which must be determined based on its inverse relation to the SN ratio. Using a specially developed binder, we demonstrate that a highly durable magnetic tape capable of withstanding more than 108 head scan passes is possible, that the use of lapping treatment can improve the SN ratio by 4 dB, and that a suitable value for the magnetic pigment content is on the order of 68‐72%.
Electrical characteristics in indium thin oxide (ITO)/selenium heterojunction
Authors: Nakada Tokio , Kunioka Akio
Published: July 2007

Although low‐cost solar cells based on Se have recently been examined, there have been extremely little basic data which provide a guideline for the improvement of energy conversion efficiency. In this paper, to clarify the behavior of heterojunctions between Se and conductive oxides, an ITO/Se heterojunction has been fabricated and its basic electrical characteristics and impurity concentration distribution by x‐ray photoelectron spectroscopy have been studied. The ITO/Se heterojunction can be regarded as a Schottky contact based on capacitance‐voltage (C‐V) and photoelectric response characteristics. Also, in the current density‐voltage (J‐V) characteristics, the slope of ln J vs. V is constant regardless of temperature. This has been explained in terms of the tunneling mechanism through interface states; Te (20 Å) introduced at the ITO/Se interface not only prevents the peeling of Se film during the thermal crystallization process, but also improves the diffusion potential and the barrier height by 10%. Although a part of the Te thermally diffused into Se layer forms an acceptor level and changes the impurity doping distribution, it does not especially affect the energy band, the J‐V characteristics or the spectral response. Since the diffusion potential determined from the C‐V characteristics is approximately 1.5 times the open circuit voltage under AM illumination, this implies that SIS (Semiconductor‐Insulator‐Semiconductor) structures are more suitable for Se‐based solar cells.
Theoretical investigation of a gap coupling of two dielectric slab waveguides with arbitrarily shaped ends
Authors: Nishimura Eiichi , Morita Nagayoshi , Kumagai Nobuaki
Published: July 2007

An integral equation method is used to analyze the scattering of the incident guided mode at the gap between two dielectric slab waveguides with arbitrarily shaped ends. As a typical example, a two‐dimensional model of the coupling gap, which occurs in the preheating stage of the fusion splicing of optical fibers is treated. The possibility is studied for indirect understanding of the situation of the coupling location from the measured values of the reflected light, transmitted light, etc. A detailed study is done for the correlation of the reflected, transmitted, radiated power and radiation patterns with the gap width and the end shape (functions of the preheating time). The reflected, transmitted, and radiated power change quickly within a short period but without significant characteristics. However, their envelopes indicate characteristic tendencies. The maximum of the reflected power and the difference between the maximum and minimum of the transmitted power decrease monotonically. The backward, rather than forward, radiation pattern varies more sensitively to the change of the end shape.
Analysis and characterization of corrosion products on gold‐plated contacts for electrical contacts
Authors: Ishino Masakazu
Published: July 2007

Methods for measuring the thickness and composition of corrosion products due to pin‐holes on gold‐plated contacts using an energy dispersive X‐ray analyzer are described. The thickness and composition of the corrosion products measured using the methods are also described, and their effects on electrical characteristics of the contacts are discussed. The thickness of the corrosion products is about 1 μm at the center of the pinhole and decreases in the peripheral area. The corrosion products in the peripheral area consist mainly of copper sulfate of lower resistivity and less copper oxide which has higher resistivity. This results in higher contact resistance in the center of the pinhole and lower contact resistance in the peripheral area. However, the contact resistance rarely exceed 60 O even at the center. Electrical and mechanical breakdown phenomena of the corrosion products are also discussed. It is shown that continuous poor contact is rarely caused by corrosion products on gold‐plated contacts.
Suppression of noise of echo sounder using exponential smoothing method
Authors: Shigeyasu Kuniyuki , Ogasawara Motoyasu
Published: July 2007

The method of noise cancellation of echo sounder using a logical data product has been used in the presence of clutter noise and interference noise. However, significant data for multioverlapping noise cancellation may be eliminated by this method. To solve this problem we study the noise suppression by the averaging method and select an exponential smoothing method which requires a small amount of memory and is computed quickly. Additionally, by using jointly a table‐lookup method for division, the computation time is shortened considerably. Consequently, it becomes clear that noises on color display are suppressed remarkably and schools of fish are revealed clearly due to the smoothing effect. This paper discusses the application of the exponential smoothing method to noise processing and its effectiveness.
Transmission characteristics of one‐dimensional image fiber‐strong coupling case
Authors: Mori Kensuke , Yamaguchi Shoji , Hosono Toshio
Published: July 2007

When an image is transmitted over a long distance by an image fiber in which a great number of homogeneous fibers is bundled, cross‐talk (mode coupling) is easily introduced and the resolution is decreased by blurring. In this paper, an exact numerical analysis of the transmission characteristics (cross‐talk characteristics) of one‐dimensional image fiber, constructed by arranging a finite number of homogeneous dielectric slabs at equal spacing, is carried out by means of wave‐optics for the strong coupling as well as the weak coupling case. The main conclusions drawn from this research are:

(1) The weak coupling approximation theory on the cross‐talk characteristics of the image fiber is applicable to the case, which is usually considered as strong coupling.

(2) When N element fibers are bundled in an image fiber, the mode generation is removed and each mode of single fiber separates into N different modes, some of which, if coupling is too strong, may turn into leaky modes.

(3) The girth of the image fiber has an effect similar to that of a perfect conductor.

(4) If the mode coupling in an image fiber is used deliberately, the structure can be used as a spatial image processing element such as planar lens, spatial filter, etc.
Electrical properties of anodized hf thin‐film capacitors
Authors: Noya Atsushi , Umezawa Toshiji
Published: July 2007

Thin‐film capacitors of Hf‐HfO2‐Al are fabricated by anodizing the Hf film deposited on a glass substrate by r.f. diode sputtering. The dependence of electrical properties on the anodizing voltage and the heat‐treatment temperature has been studied experimentally. In the capacitor fabricated with anodizing voltage of 40 V, the capacitance density is found to be 0.257 μF/cm2 and an appropriate heat treatment can improve the tan Δ of 0.0026 and the temperature coefficient of capacitance of 230 ppm/°C. These values are comparable to those for the capacitor with the anodizing voltage of 160 V. The capacitor electrical properties improve with heat treatment in the temperature range of 100 to 300°C so that the thermal stability is increased. It has been confirmed from these results that the anodized Hf thin film can be a useful dielectric material for a capacitor with a large capacitance density fabricated with a low anodizing voltage. By means of Auger electron spectroscopy, the depth profiles of these capacitors have been studied. The thickness of the nonstoichiometric interface layer between the anodized oxide and the base hafnium metal varies by the anodizing voltage and the heat treatment. The tan Δ of the capacitor is especially closely related to the thickness of the interface layer.
Temperature resolution of a noninvasive thermometry for hyperthermia using NMR
Authors: Kamimura Yoshitsugu , Amemiya Yoshifumi
Published: July 2007

Thermometry of the deep interior of the human body should be realized in a noninvasive way when clinical hyperthermia is applied to cancer therapy. This paper describes temperature resolution of a noninvasive thermometry using temperature dependence of the thermal equilibrium magnetization MO in the nuclear magnetic resonance (NMR) measured by the magnetic field focusing method.

In this paper, it is assumed that temperature errors are caused by: (a) the relaxation time; (b) incomplete focus; and (c) the thermal noise of the measurement system when (1) the temperature dependence of MO approximates to water, and (2) the influence of blood flow is negligible except in the main arterial region. The effects on temperature errors are studied and, as a result, the relations between the temperature errors and parameters of the measurement instrument are determined quantitatively. For example, a temperature measurement with an error of °0.5°C in a small cylinder 4 cm in diameter and 4 cm long requires that the current for a line‐shaped magnetic field and the current for gradient field be 9.89 kAT and 2.51 kAT, respectively. Here, the resonance frequency is 4 MHz and the cut‐off frequency of the low‐pass filter is 100 Hz.
High‐speed thin‐film thermal print head
Authors: Shibata Susumu , Kanamori Takashi , Kuroki Kenji
Published: July 2007

This paper describes the result of thermal analysis of the inner region of the thin film thermal print head and the effect of the shape of the meander type heating resistor. The thermal head allowing short pulse driving for higher speed with higher reliability has been demanded recently. The influence of the pulse duration on the temperature profile of the inner region of the head and the heating resistor shape have not been studied.

We have studied various conditions affecting the temperature profile of the inner region of the thin film thermal print head and the shape of the meander type heating resistor, and obtained the following results:

1. As the pulse applied to the heating resistor gets shorter, the necessary power for pulse application increases and the temperature slope in the heat insulating layer near the heating resistor becomes steeper.

2. To lessen the temperature slope in the heat insulating layer, thinning the protective layer, increasing the thermal conductivity of the protective layer and preheating the whole inner region are effective.

3. In surface temperature distribution, corners of the meander type heating register become hotter as the width of the pulse applied to it becomes shorter. Widening the heating register at corners, narrowing the straight parts and increasing the number of meanderings are effective.
SHG in a slab‐type waveguide with a 2‐methyl‐4‐nitroaniline crystal as a high index top layer
Authors: Sasaki Keisuke , Kinoshita Takeshi , Karasawa Naoki
Published: July 2007

Recently, it has been recognized that organic materials have a very large nonlinear optical constant compared with non‐organic materials (e.g., KDP and LiNbO3). It has been known that 2‐methyl‐4‐nitroaniline (MNA), among them, has an extremely large SHG tensor, although this has a disadvantage in that the d11 component cannot be matched in phase in the bulk crystal state. When an MNA single‐crystal made by using the vapor‐phase method and shaped in a thin parallelogram, is set on a tapered slab‐type thin‐film waveguide appropriately, and the fundamental wave is applied as a TE wave, it is possible to match the phase of the fundamental wave and the phase of the second harmonic wave at a certain waveguide thickness. Since the refractive index of the MNA is greater than that of the slab‐type waveguide film, an SHG is observed at the resonating film thickness when the high‐refractive‐index top layer is used. The observation of the second harmonic (0.532 μm) was made by using an Nd:YAG pulse laser (1.064 μm) for the fundamental wave. The phase matching point was examined from the dispersion curves which was calculated from the waveguide structure parameter. The results show that this phenomenon is the conversion from the TE first of the fundamental wave to the TE second of the secondary harmonic. The efficiency of the MNA observed was not great since the overlapping of the two wave types is not large.
Brightness distribution in rf‐sputtered zns:tbf3 electroluminescent panels
Authors: Mikami Akiyoshi , Ando Keiichi
Published: July 2007

Thin‐film ZnS:TbF3 was deposited by sputtering and a thin‐film electroluminescent panel having a display area of 34 mm × 34 mm was fabricated. The brightness distribution was investigated and film thickness variation and distribution of Tb luminescence centers were studied in conjunction with the brightness. It was found that uniformity of the brightness increases as the applied voltage increases and frequency decreases. Relative brightness deviation (Bmax ‐Bmin,)/Ba, where Bmax, Bmin and Ba indicate maximum, minimum and average brightness, respectively, of the film was 13 to 23% when it was driven by 5 kHz, 40‐V voltage. It was observed that brightness distribution depends on film thickness of the ZnS:TbF3 layer and that the thinner part has higher brightness. Based on the consideration that thickness variation causes irregular field intensity as well as the conduction charge distribution, and results in brightness variation, we calculated the brightness deviation and found that it agreed well with the experimental results. It was also demonstrated that Tb ions were scattered uniformly in the sputtered ZnS film, which was proved to have uniform luminescence center distribution.
Edge‐junction type nanometer bridge
Authors: Yamashita Tsutomu , Hamasaki Katsuyoshi , Matsumoto Kazutaka , Kodaira Yoshimitsu , Komata Toranosuke
Published: July 2007

An edge‐junction type nm (nanometer) bridge is fabricated which has bridges on the joint of the edges of two Nb films. Each nm bridge has an effective length of less than 50 nm, width about 2 μm, and thickness from 30 to 60 nm. To make a good edge‐junction type nm bridge, it is necessary to form a sharp edge on an Nb film. For this purpose, dry‐etching with a teflon holder in an He gas was used. Voltage steps up to about about 100 μV induced by a microwave were observed in the fabricated device, and the value of IORn greater than 50 μV was obtained. By measuring the threshold characteristic of a DC‐SQUID consisting of this nm bridge, it was confirmed that the current‐phase relation of the bridge is sinusoidal. The temperature range in which this sinusoidal relation is kept is as wide as 4 to 6 K approximately.
Thin‐film energy‐transfer dye lasers in spectral region of near ultraviolet to violet
Authors: Muto Shinzo , Shiba Fumikazu , Sano Seigo , Ito Chiaki , Inaba Humio
Published: July 2007

The development of the thin‐film waveguide dye lasers has created extensive applications in laser technology and fiber optics. This paper reports the laser properties of two types of thin‐film energy‐transfer dye lasers (thin‐film ETDL). One is the mixture‐type doped with a donor‐acceptor dye pair in the polymer thin‐film waveguide, which operates largely by nonradiative resonance transfer; the other is two‐layer type with the active core (layer of acceptor dye) and clad (layer of donor dye), which operates only by radiative transfer. These ETDLs are pumped by an N2 laser and operate efficiently as practical compact laser sources in the spectral region of near ultraviolet to violet. Furthermore, the measurement of the energy transfer rate constants in these ETDLs is also presented.
A new thin‐film electroluminescent device with a gate layer and its properties
Authors: Hirate Takashi , Ito Takahiro
Published: July 2007

A novel structure is proposed for thin‐film EL devices which incorporates a gate layer (of various materials) into the active layer (ZnS, etc.) of a conventional insulator‐active layer‐insulator structure. Such devices have been fabricated and their characteristics investigated. The result was that especially for gates made of metal or semiconductor materials, characteristics completely different from conventional devices were found. That is, when a metal or semiconductor gate had a thickness of ≥1000 Å, only one of the two active layers sandwiching the gate exhibited luminescence, and which one, was the opposite in the metal and semiconductor cases. Further, for an Al gate, the single luminescent active layer was reversed for thick and thin (200 Å‐500 Å) gates and making the gate even thinner (∼100Å) resulted in both layers being luminescent. In this latter case, a very significant result was obtained that by doping the active layers with ErF3 and SmF3, respectively, a continuously variable color ranging from light yellow to orange could be obtained by changing the driving voltage or frequency.
A switching‐mode ultralow‐frequency signal delayer and its application
Authors: Sekiguchi Tsutomu , Tsukamoto Kazumi , Kaku Shukichi , Shimooka Yasuyoshi
Published: July 2007

The signal delayer is presently an important device in measurement and automatic control. The schemes for the signal delayer presently used have some problems. This paper extends the already‐known PWM delay method [1] and proposes an ultralow‐frequency signal delayer achieved by means of the switching‐mode system, which controls the on‐phase of the switching element based on the comparison point information between the input signal and the specified bias. The principle and the basic configuration are described first. The operating signal waveform of the proposed signal delayer is analyzed. The condition for the output signal and the possible range of generated signal waveforms are discussed. Then a delay method by waveform conversion is described based on the principle of the switching‐mode operational amplifier, indicating the applications to various kinds of ultralow‐frequency signal generators. An experiment was performed of the comb filter composed by the delayer. It is shown that the system can be used as an ultralow‐frequency difference device and can be applied to the arbitrary transfer function generator and waveform equalizer. In particular, it is shown that the device is useful as a high‐power delay operator for ultralow‐frequency regions.
Analyses and experiments of nonlinear phenomena in piezoelectric semiconductors
Authors: Yamanouchi Kazuhiko , Inada Tsutomu
Published: July 2007

Since a GaAs semiconductor has a piezoelectricity and a high mobility at the same time, it has attracted the attention of many research workers as material for surface‐acoustic‐wave (SAW) devices utilizing its nonlinearity. However, in published works, the analyses have regarded a semiconductor substrate as a piezoelectric element, or an epitaxial‐growth film as a semiconductor. Also, some analyses of a piezoelectric semiconductor were limited to a one‐dimensional model, or to obtaining the velocity and attenuation of the surface wave by using the perturbation method.

In this paper, a numerical analysis of the SAW on a general piezoelectric element is carried out. The propagation characteristics of the SAW for the carrier density of a semiconductor, the convolution efficiency for the carrier density, and its dependence on the mobility represent new findings. Also, the results of analyses on a double‐layer are shown. Also, the experimental results of the excitation characteristics of an SAW on a GaAs piezoelectric element, and the output of the convolution relating to the carrier density are shown.
Recovery voltage in dielectric absorption of capacitors and consideration by using an equivalent circuit
Authors: Miyairi Keiichi , Yazawa Kazuhiro
Published: July 2007

A voltage appearing between the electrodes of a charged capacitor, after it is discharged by short‐circuiting its electrodes, is known as a recovery voltage. A test method by which the dielectric absorption of a capacitor is calculated from its recovery voltage is described in the Japanese Industrial Standard (JIS). In this paper, the effect of the applied voltage, charging time, discharging time, and input impedance of a voltmeter, on the recovery voltage is investigated experimentally. The dielectric absorption is also investigated theoretically by using an equivalent circuit of the recovery voltage. It was found experimentally by using polystyrene capacitors that the greater the input impedance of the voltmeter, the greater the dielectric absorption calculated from the recovery voltage, and the shorter the discharge time, the greater the dielectric absorption. These relationships were confirmed by a computer simulation based on the above‐mentioned theory. It has been concluded that the input impedance of the voltmeter used for measuring the recovery voltage should be higher than the leakage resistance of the capacitor under test.