bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hybrid clock synchronization: Condition for the existence of steady state in a ring network
Authors: Yahata Haruki 
Published: July 2007

AbstractIn the clock synchronization of the closed area network (such as local area network (LAN) and metropolitan area network (MAN)) to the wide area network, it is advantageous to use the hybrid synchronization from the viewpoint of reliability, where the master‐slave synchronization is applied at several points from the wide area network, and the mutual synchronization is applied within the closed area network.This paper considers the case where the hybrid synchronization is applied to the ring‐type area network and derives the condition for the existence of the stable phase state. When the synchronization circuit is a two‐input complete integrating second‐order PLL with the sinusoidal or equilateral triangular phase comparator characteristic, the sufficient condition for the existence of the stable phase state of the whole network is that the ratio of the gain for the mutual synchronization to the gain for the master‐slave synchronization is less than 1 in at least one PLL. When the synchronization circuit is the incomplete integrating PLL, the sufficient condition is that the above gain ratio is less than a certain limit in at least one PLL, and the ratio is above the inverse of that limit in other PLL, where the limit is less than 1 and is determined by the difference between the input frequency from the wide area network and the center frequency of PLL as well as the magnitude of the gain. The above properties are shown theoretically and are verified also by computer simulation.
Optical fiber cable extension method applicable to the large demand distribution
Authors: Morita Hideyo , Tsujino Masayuki , Ikeuchi Noriyuki 
Published: July 2007

AbstractOptical access networks are important for developing an information infrastructure. When an optical fiber is first introduced, the demand generated varies greatly so an optical fiber cable extension method to address this is necessary. This paper uses the concept of fixed fiber and common fiber, both of which are used in the conventional method as the base, α, and proposes a new method to find the optimal extension amount to meet the large demand deviation. First, a method for determining the amount of common fiber extension that satisfies the required reliability with respect to the fixed‐fiber extension is introduced. Next, a simulator to simulate the extension of both the fixed and common fiber is developed to determine the total cost for the various fixed‐fiber extension parameter. Using this procedure, an optimal amount of fixed‐fiber and common‐fiber extension is found as parameters such as average demand and standard deviation. The proposed method is then shown to produce more economical planning than the conventional method.
Fan‐beam forming for a linear antenna with exponential‐tapered amplitude distribution
Authors: Konishi Yoshihiko , Ohtsuka Masataka , Matsunaga Makoto , Urasaki Shuji 
Published: July 2007

AbstractAs a fan‐beam forming method for a line source having an exponential‐tapered amplitude distribution simulating the linear array antenna or a linear antenna with a traveling‐wave feed such as in the multifilar helical antenna, this paper investigates a method in which the entire source is divided into n : 1 and the excitation phase in the 1/(n + 1) portion is π shifted. First, the fan‐beam forming method is studied analytically for a linear source with an exponential‐tapered amplitude distribution so that the equation needed for realizing a fan beam is derived. Next, in the case where a fan beam is formed for the determined coverage angle (angle θ = 30–60°) from the zenith, the relationship between the total length LT of the source and the coverage gain is studied. It is shown that the coverage gain can be improved by forming a fan beam. It is shown also that there exists an optimum value of the total length of the source maximizing the coverage gain for a given coverage area. Further, by using a bifilar helical antenna, a fan‐beam forming experiment is carried out. It is confirmed that a fan beam close to the computed value can be formed and the coverage gain can be improved although there exists asymmetry in the measured radiation pattern.
Two‐dimensional numerical analysis for high electron mobility transistors (HEMTs)
Authors: Yoshida Jiro , Kurata Mamoru 
Published: July 2007

AbstractA two‐dimensional numerical model has been developed for the analysis of operation of a high electron mobility transistor (HEMT) based on the AlGaAs/GaAs heterojunction. In this model, the basic equations are formulated under the assumption that the band structure is continuous and Boltzmann statistics are applicable. Further, it is assumed that the velocity‐electric field curve of the two‐dimensional electron gas system is identical to that of the bulk GaAs. The calculations have been performed for the device with a 1 μm gate length and the following results have been made on the operating mechanism of the HEMT. 1 In the short‐channel HEMT, the electron velocity saturates in the channel directly below the drain‐side edge of the gate electrode and as a result the current also saturates. 2 In the HEMT operated in the saturation region, an electron accumulation region is formed in the GaAs layer below the drain‐side edge of the gate electrode. In this region, the current flow significantly extends into the bulk GaAs from the heterojunction interface. 3' A strong electric field concentration occurs in this region and the major portion of the applied drain voltage is sustained by this region. This concentration is limited in an extremely narrow region.
Built‐In ECC techniques for LSI memories
Authors: Yamada Junzo , Mano Tsuneo , Date Shigeru 
Published: July 2007

AbstractBuilt‐in Error Checking and Correcting (ECC) is essential for megabit level dynamic MOSRAMs to reduce an alpha parcle‐induced soft error rate. As the one‐bit per multicell ECC method makes a one‐bit item of information from multiple memory cell items of information, a one‐bit per three‐cell method and a one‐bit per two‐cell method are proposed. Next, encoding methods for items of memory cell information on an identical word‐line, namely, the bidirectional parity method and the Hamming code method are proposed and their logical structures are clarified. The advantages and disadvantages of these techniques are compared from the viewpoints of memory overhead, error correcting time and the soft error rate. As a result, it is shown that an ECC method using a bidirectional parity code is best suited for a built‐in ECC applicable to megabit level dynamic RAMs.
A time‐dependent and two‐dimensional device analysis of CMOS structures
Authors: Odanaka Shinji , Wakabayashi Mutsuko , Ohzone Takashi , Takemoto Toyoki 
Published: July 2007

AbstractLatchup phenomena are becoming important problems for increased density CMOS integration. Here, a 2‐dim device simulator is used for transient analysis of latchup phenomena in CMOS structures. The dynamic characteristics of the latchup turn‐on process due to parasitic MOSFET or direct forward biasing are investigated. From this, difficulties for scaling the n‐well CMOS structure, and the design of latchup resistant CMOS devices are considered. Also discussed will be the effectiveness for device design of applying two carrier 2‐dim device simulators to large area devices with complex shapes, such as typified by the CMOS structure.
Two‐dimensional modeling based on boltzmann transport equation for ion implantation
Authors: Takeda Tadao , Yoshii Akira 
Published: July 2007

AbstractA highly accurate analysis method based on the two‐dimensional Boltzmann transport equation is proposed for ion implantation. In this method, the ion energy and traveling angle distributions are quantized so that the analysis of the diffusion and scattering terms in the Boltzmann transport equation is simplified. Also, the degradation of the analysis accuracy due to the above quantization can be avoided by newly introducing the packet beam model. To show the validity of this method, As+ and P+ ion implantation into Si and SiO2 substrates is analyzed and the results are compared with the experimental data. Consequently, the calculated impurity distributions agree well with the experimental results and hence this agreement indicates the high‐accuracy of the method. Also, the ion‐irradiation‐region dependence on the impurity distribution is successfully shown. From the energy deposition and subsequent heat generation in the substrate by ion‐irradiation, it is indicated that the thermal impurity diffusion toward the substrate surface is possible. Moreover, it is indicated that the channeling effect must be considered for the low‐energy, P+ ion implantation. Finally, the deviation of the SiO2 stopping cross section from Bragg's rule is obtained using this method.Thus, using this method, the ion implantation can be analyzed so accurately that complex and fine structured devices can easily be designed.
Epitaxial growth of gaas on ge/si substrates by mocvd
Authors: Okamoto Kotaro , Yukawa Teizo , Asano Yasanori 
Published: July 2007

AbstractGe was deposited on n‐type (100) Si substrates by electron beam evaporation and it became clear that to obtain good morphology of a single‐crystal Ge layer, the conditions of crystal growth should be maintained as follows: pressure should be less than 10‐6 Pa, the temperature range should be 400‐500°C, and the growth rate should be kept less than 7 Å/s. Moreover, in the growth of GaAs, it was found that we can obtain an epitaxial layer of monocrystalline n‐type GaAs if we use the MOCVD method in which trimethyl gallium (TMG: (CH3)3 Ga) and arsine (As H3) are used, silane (SiH4) is used an an n‐type doping gas, the temperature range is 590 to 670°C, the mole ratio of As H3/TMG is 10 to 24, the mole ratio of Si H4/TMG is 2‐5 × 10‐3, and the growth rate is kept below 0.4 μm/min. Zn diffusion is done on n‐type* p‐n junctions, and the resulting light‐emitting diode was observed to have electroluminescence at the peak wavelength of 897 nm at room temperature. In the case of GaAs/Ge/Si structure, the thermal expansion coefficients of Si and GaAs are different and tension is produced so the spectrum shifts to the longer wavelength. Moreover, if the thickness of the GaAs layer becomes less than 5 μm, then cracks are produced.
Finite‐element analysis of periodically perturbed piezoelectric waveguides
Authors: Mitobe Seiichi , Koshiba Masanori , Suzuki Michio 
Published: July 2007

AbstractThe propagation velocity of the acoustic wave can be reduced in a periodic acoustic waveguide (periodic waveguide) on which a periodic perturbation is added along the propagation direction of the acoustic wave. The passband and stopband appear in the dispersion characteristics (Brillouin diagram). The structure is used widely for the delay line, filter, reflector and resonator. The design of these devices made of periodic waveguides requires the Brillouin diagram. The objective of this paper is to develop a method that can be used to derive the Brillouin diagram of the periodic piezoelectric waveguide receiving an arbitrary mechanical or electrical perturbation. A method based on the finite element method is proposed and its formulation is presented. Further, for the periodic waveguide used as a reflector, the stopband width and the shift of the center frequency are calculated. These are important parameters for the design of the reflector. The groove reflector and the metal strip reflector are analyzed and the results are found to agree well with the experimental values.
High‐sensitivity analysis of impurities in gaas using multi‐element‐doped gaas standard samples
Authors: Kurosawa Satoru , Homma Yoshikazu , Yamawaki Masataka , Tanaka Tohru 
Published: July 2007

AbstractIn order to improve the quality of GaAs crystal, it is indispensable to conduct ultramicroanalysis of impurities in GaAs. For the analyses in this paper standard samples were made by adding a certain amount of impurities which can adequately be detected by chemical analyses. Using these samples, the SSMS, SIMS and chemical analysis methods are examined. The results are: (1) three chemical analysis methods (FLAA, ICP and colorimetric methods) are examined and permit a detection limit of 0.05 ∼ 5 ppm and a CV value of ±30%. (2) For the SSMS method, a process for making a specimen electrically conductive by applying a vacuum‐evaporated silver film is introduced. Comparing this result with those obtained by the chemical methods, a relative sensitivity factor is found which permits determination of the absolute value and it is possible to conduct analysis with detection limits of 10 ∼ 30 ppb and CV value of ±30%. (3) For the SIMS method, the secondary ionization yields for B, Al, Si, S, Cr and Mn are obtained, by comparison with the results of chemical analysis, which makes absolute quantitative analyses of these elements possible. The accuracy of quantitative analysis in which ion‐implanted specimens were used for the standard samples is confirmed.
High‐rate syntheses of high tc superconducting nbcxn1‐x films by hollow‐type target sputtering
Authors: Yamamoto Hiroshi , Ishii Koichi , Tanaka Masaichi 
Published: July 2007

AbstractA new high‐speed sputtering method using a hollow target is proposed. Its model analysis and experimental examination are carried out. As a result, it has been shown that a high‐speed film synthesis without damages from high‐energy particles is possible. This is not only because the plasma discharge is confined inside the target resulting in high density, but also because the particles sputtered from the target inner wall lose considerable energy due to collisions. In the actual experiments, by argon sputtering a small hollow cylindrical Nb target with inner wall area of 33 cm2, a high deposition rate of more than 200 nm/min has been obtained despite a very simple electrode configuration. Furthermore, as a result of applying this method to the NbCxN1‐x film formation by reactive sputtering with nitrogen, it has been verified that a high‐speed film synthesis with more than 60 nm/min is possible. In addition, a high‐quality film with superconducting critical temperature of 17.7 K in the composition range of x = 0.1–0.3 can be obtained. Moreover, this film shows a peculiar preferential growth in the (200) plane on a high‐temperature substrate.
Judgment of outlying observations in automatically measured SI wafer inspection data
Authors: Aoki Yukio , Toyabes Tooru , Shimada Shozo , Sato Shoji 
Published: July 2007

AbstractResearch and development of LSIs require rapid evaluation of the characteristics of fabricated devices. For this purpose automatic measurement systems have been developed in various laboratories. Some outlying data unavoidably exist in the data collected by the automatic data acquisition system, and it is necessary to judge the outliers in data processing. In this paper two algorithms to judge outliers are examined and one new algorithm is presented. They applied for Si wafer inspection data collected automatically. The three algorithms are the outlier judgment method proposed by Grubbs, the judgment method using Mahalanobis's distance and the method combining the principal component analysis method with the latter method. The conclusions are as follows:
Grubb's method is easy to use for one kind of measured items
Mahalanobis's method is useful for several kinds of measured items and is especially effective when they are correlated
The combination of the principal component analysis method and the method by Mahalanobis's distance is useful in saving manpower for routine judgment of the same data produced in the same line for several measured items.
Radiation from a circular bend of step‐index single‐mode fibers
Authors: Morita Nagayoshi , Tanaka Toshiaki , Kumagai Nobuaki 
Published: July 2007

AbstractThe problem of radiation from a uniform bend of step‐index single‐mode fibers is analyzed in detail. Unlike the previous methods of approximate evaluation of the bending loss of fibers, a strict analysis of the radiated electromagnetic fields is performed. A detailed study of the electromagnetic fields, radiated in the neighborhood of the junction of straight and bend portions, which have not been studied fully so far, is performed here. The radiated field is expressed in integral form, using the mode field on the curved surface circumscribing the core in the cladding, and the far field expressions are determined using the stationary phase method. From these results, many factors that had not been clarified before such as the degree of contribution of mode field components and radiated power, the direction of travel of radiated light, and radiation patterns, etc., are evaluated in detail in addition to the evaluation of radiation losses with greater precision. Moreover, the numerical examples for the radiation from the starting portion of a bend in the curved fiber, and the radiation patterns in the fiber cross‐section plane when radiation is uniform, are also shown.
Relationship between losses under a large flux excitation and small signal loss factors tanδ in magnetic cores for high frequency use
Authors: Sakaki Yo , Sato Toshiro 
Published: July 2007

AbstractFor the evaulation of magnetic core losses in a high‐frequency region, the small‐signal parameter tan δ or the relative loss coefficient tan δ/μs, which are a small‐signal parameter in the region of an initial permeability, has been used. The magnetic cores for transformers or reactors have recently been used at a frequency greater than 100 kHz, and with a magnetic flux density far greater than the initial permeability, due to the demands of miniaturizing switching power supplies. This paper examines the relationship between the large‐signal loss of magnetic cores and their tan δ in a frequency range of 1 kHz to 1 MHz. It was found that the large‐signal loss has poor correlations with a small‐signal parameter, such as tan δ or tan δ/μs. ‘A loss‐evaluation parameter’ ζ = tanδ/μs (1 + tan2δ) was newly introduced. It is shown that the large‐signal eddy‐current losses of most magnetic cores at a frequency greater than 100 kHz can be estimated with a high accuracy by using this parameter; ζ is expected to be a useful parameter for evaluating the losses of cores for power applications at a frequency greater than 100 kHz.
Improvement of the spatial resolution of ultrasonic imaging using the holographic technique
Authors: Ikegami Masiki , Yamamoto Tsuyoshi , Aoki Yoshinao 
Published: July 2007

AbstractIn the conventional synthetic aperture technique the antenna directivity is assumed to be wide enough that sufficient phase information can be obtained with antenna scanning. This assumption is made in the experimental studies as well. With a sharp antenna directivity, however, sufficient phase information cannot be obtained and the reconstructed image obtained by the conventional synthetic aperture technique has poor resolution. On the other hand, if the real aperture technique is employed, an image of improved quality can be obtained with a sharp antenna directivity and the resolution increases as the directivity becomes sharper. The present paper deals with the case of directivity which is too sharp for the synthetic aperture technique and too wide for the real aperture technique. Theoretical and experimental studies are made on ultrasonic imaging by using the modified synthetic aperture technique for this case. Specifically, the actually measured point spread function is used in the synthetic aperture technique and it is confirmed that a higher resolution can be obtained in this way than by the conventional synthetic or real aperture technique.
Switched‐capacitor realization of a fourier analyzer using integral feedback capacitance circuit
Authors: Sasaki Itsuo , Okabe Kaoru , Yoneda Shojiro , Kasai Tamotsu 
Published: July 2007

AbstractThe technique of forming a discrete Fourier transform (DFT) circuit with an analog circuit has numerous attractive features not available in the DFT circuit with a digital circuit. For example, frequency analysis can easily be carried out and real time processing is possible. The switched‐capacitor (SC) circuit has recently been considered suited for MOSIC of analog circuits. In this paper, a DFT circuit is constructed with an SC circuit in an analog format so that circuit integration is possible. For SC realization of a DFT circuit, an integral feedback capacitance circuit has been proposed for a signal processing circuit. This circuit makes use of the feedback capacitance terminal voltage of an integrator made of an operational amplifier. It is used for the SC sample‐and‐hold circuit and the SC multiplier and adder. This SCDFT circuit has been fabricated with discrete components and the operating principle has been confirmed.
Magnetostriction of co‐based alloy films for magnetic recording
Authors: Matsuoka Morito , Naoe Masahiko , Hoshii Yoichi 
Published: July 2007

AbstractThis paper evaluates the magnetostriction in various kinds of Co–based alloy sputtered film for magnetic recording, especially Co film and Co–Cr film for vertical magnetic recording, Co–Cr–M film containing a third element (Fe, Ta and Zr) and Co–Pt film with large face–angle ratio. The result shows that evaluation of the magnetostriction is useful as measure of the extent of stress–induced demagnetization in a medium for magnetic recording and also in prediction of the microscopic structural changes peculiar to Co–based alloys, where α(fcc) high–temperature phase is mixed in the film by α–ϵ transition. Consequently, it is concluded that the evaluation of demagnetization is useful for evaluation of Co–based alloy film medium. By simultaneously measuring the magnetostriction and the stress–induced demagnetization one can determine the value of λc, which is one of the magnetostrictive constants in C–oriented film and has been difficult to determine by other methods.
Method for measuring the glossiness of curved surfaces using charge‐coupled‐device line sensor
Authors: Aida Teizo , Serikawa Seiichi , Tamura Hiroyuki , Kugisawa Hideo 
Published: July 2007

AbstractThe method for measuring the glossiness of a plane object is regulated in JIS Z 8741. However, no method has been established for the glossiness of a curved surface. For instance, the psychological glossiness Gph to humans depends on the radius of curvature of the object even if the material and the surface finish are identical. However, the conventional physical glossiness is almost unrelated to Gph. A system for measuring the indistinctness‐degree glossiness GID has been fabricated with a light source, an optical system (lens and slit), and charge‐coupled‐device (CCD) line sensor. This equipment has been used to measure GID of metal spheres of various radii, enamel‐coated spheres, and a spherical pearl of 8 mm diameter. In all samples, a strong correlation with a correlation factor more than 0.88 has been observed between GID and the psychological glossiness GID. From this fact, it has been found that GID is effective as a physical glossiness of a curved surface with a relatively large glossiness such as the curved surface of a metal body, painted body and spherical pearl. On the other hand, GID is not suited for a curved surface with a low glossiness such as paper and plastic or for a highly glossy metal surface with a mirror finish.