bluuebunny/crossref_metadata_2025_split huggingface dataset:
An analysis of the effective radiation efficiency of the normal mode helical antenna close to the human abdomen at 150 MHz and consideration of efficiency improvement
Authors: Ogawa Koichi , Koyanagi Yoshio , Ito Koichi 
Published: August 2002

AbstractIn this paper, a new radiation efficiency based on the available power is defined with regard to a normal mode helical antenna at 150 MHz placed close to the human abdomen, so that the power loss caused by impedance mismatch and by the resistance of the antenna itself can be taken into consideration in the treatment. In this way, the variation of the effective radiation efficiency of the antenna in a practical situation caused by the antenna length and the distance to the human body is analytically derived. Further, by deriving the loss power in each section, the factors causing degradation of the radiation efficiency are analyzed and the mechanisms for efficiency degradation are clarified. Based on the results, the possibility of improved radiation efficiency of the antenna near the human body is discussed. It is shown that the radiation efficiency of the antenna near the body is less than −20 dB, that its main cause is impedance mismatch, and that improvement of the radiation efficiency by more than 10 dB is possible by always maintaining conjugate match near the human body. These findings are experimentally confirmed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(8): 23–33, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1115
An analysis of a door seal structure of a microwave oven with an inserted sheet‐type lossy material using FDTD method
Authors: Matsumoto Kouta , Kusama Yuusuke , Hashimoto Osamu 
Published: August 2002

AbstractBy means of the three‐dimensional FDTD, the shield effect is studied for a sheet‐type lossy material inserted in the gap between a microwave oven body and its door as a way to suppress the microwave leakage in place of the generally used choke structure. Specifically, the shield effect versus the inserted length of the lossy material and the gap is studied by means of the TE40 mode, which has the closest shape to the leakage field among various higher‐order modes. It is shown that a shield effect of more than 30 dB can be exhibited if a certain lossy material completely fills the gap and that the inserted length of more than 50 mm is needed to obtain a shield effect of more than 30 dB if there is gap of 1 mm. Hence, the shield effect in a practical situation is quantitatively confirmed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(9): 13–20, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1121
A frame timing and carrier frequency synchronization scheme for OFDM using frequency‐shifted signal
Authors: Konishi Muneo , Hosokawa Taisuke , Maeda Tsuyoshi , Takahata Fumio 
Published: August 2002

AbstractThis paper proposes a scheme for realizing simultaneously frame timing and carrier frequency synchronization in OFDM systems for wireless packet communications. Data symbols, which are frequency shifted by the half of subcarrier spacing based on the pattern of Barker sequence, are utilized as pilot symbols for the synchronization. The reduction of transmission efficiency could be minimized by carrying the data information on the pilot symbols. The performance evaluation by means of computer simulation demonstrates the good characteristics of the proposed system against the small Doppler frequency shift. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(10): 74–83, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1133
A study on efficient information search with agents in a large‐scale network
Authors: Sugawara Shinji , Ohshima Takamitsu , Yamaoka Katsunori , Sakai Yoshinori 
Published: August 2002

AbstractIn this paper, we study improving the efficiency of search methods to search a huge, superdistributed data space like the Internet. Specifically, in a search for information by agents, we first classify the search problems into several models based on the type of agent. Next, we determine the optimal search method that minimizes the communication and processing costs and the time costs for the basic model. Then we extend the optimal technique, propose highly efficient search methods for the other models, and evaluate their characteristics. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(10): 84–95, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1134
A consideration of multipath detection in navigation systems
Authors: Tajima Hirohisa , Fukushima Sonosuke , Yokoyama Hisasi 
Published: August 2002

AbstractSome navigation systems measure the range or the angle by detecting the position of the pulse waveform. They cause some position detection errors, if the multipath wave overlaps with the direct wave with different position and phase. This paper presents a multipath detection method to improve the integrity of these systems. The results of simulation and ground‐based experiment for DME/P are described as an example, which use dual function of time‐of‐arrival detection. Each function is supposed to have a different multipath error characteristic. In addition, its multipath error detection method and application to MLS and GPS are also described. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(11): 52–59, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1137
An adaptive access control scheme for a reservation TDMA/adaptive modulation system
Authors: Watanabe Kazumi , Sampei Seiichi , Morinaga Norihiko 
Published: August 2002

AbstractIn realizing multimedia communication systems in land mobile communications, high‐frequency efficiency must be achieved, while satisfying various requirements for transmission quality depending on the media. In the proposed system, voice and the data of long message size are transmitted by the reservation TDMA (time division multiple access) system, and data of shorter message size are transmitted by the slotted ALOHA system, using slots which are not used for voice or long data. In order to ensure a larger number of idle slots for short data transmission, the voice activation technique and adaptive modulation are utilized in voice transmission. This paper considers the reservation TDMA/adaptive modulation system, and the transmission of voice/data integrated traffic at high speed and high efficiency through the common radio channel. An adaptive access control system is proposed in which the threshold for separating long and short data is automatically controlled according to traffic variation. It is verified by a simulation that the proposed system is effective in integrating data with high efficiency and in reducing delay in data transmission, while maintaining the voice transmission capacity. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(11): 77–86, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1140
Raising accuracy in the finding of radiated emission sources utilizing the CISPR emission measurement system
Authors: Ishida Yasuhiro , Murakawa Kazuo , Yamashita Kouji , Tokuda Masamitsu 
Published: August 2002

AbstractIn order to mitigate the emission radiated from electrical equipment, emission source finding methods need to be studied. In this regard, the finding method utilizing CISPR emission measurement system, which uses only amplitude data, has been proposed. However, there were some problems related to calculation convergence and dependence on initial source positions, as a result of which the finding accuracy decreases in some cases. In this paper, it is shown that the finding accuracy in this method is greatly raised when the calculation convergence is improved by optimizing Marquardt's constant, and the estimated sources are initially given at the optimum positions by taking into account the deviation (Norm) between the measured electric field and the estimated one. In order to experimentally verify this finding, unknown sources were estimated by using electric field data measured at a distance of 3 m in a semianechoic chamber, where two simulated emission sources were placed 0.4 m apart. Accurate estimated values were obtained, namely, a position estimation deviation of 0.09 m and an amplitude estimation deviation of 0.29 dB at 500 MHz. Additionally, the finding accuracy is raised by adding the directivity of the source and the receiving antenna. Furthermore, results in a fully anechoic chamber, in which the floor is covered with an electric wave absorber, show good finding accuracy, equivalent to that in a semianechoic chamber. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(6): 50–59, 2001
Performance evaluation of PRML systems using rate 9/10 trellis codes
Authors: Saito Hidetoshi , Okamoto Yoshihiro , Osawa Hisashi 
Published: August 2002

AbstractTrellis codes are a form of recording codes considered to have good compatibility with PRML systems, which are signal‐processing systems that are effective for digital magnetic recording. In this paper, trellis codes which are compatible with PR4 and EPR4 are constructed by a set partitioning method. The best trellis codes are constructed by defining a signal constellation on the basis of output symbols allowing a partial response scheme and by partially dividing sets on a multidimensional Euclidean space. It is shown that trellis codes having a coding rate of 9/10 and bundle lengths of 6 and 7 can be obtained for PR4 and EPR4 systems using Nyquist equalization, and that the SN ratios are improved by 2.4 and 2.3 dB for the existing 8/9 (0,4/4) codes for the PR4 system and 16/17 (0,6/6) codes for the EPR4 system at a bit error rate of 10–4. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(7): 58–65, 2001
Production of binary holograms with laser punch
Authors: Iwai Yoshiaki , Nakajima Masato 
Published: August 2002

AbstractA method for fabrication of binary holograms with a laser punch is proposed. In the present method, the hologram pattern is first computed in a computer so that a given reconstruction image can be obtained. This hologram pattern is binarized by a newly proposed algorithm. Based on the binary hologram pattern, laser illumination and motion of the stage with a film attached are computer controlled. In this way, holes with a fixed diameter are punched into the film to form binary holograms. Further, in order to verify the method's effectiveness, it is confirmed that excellent reconstruction images can be obtained from the holograms fabricated by the proposed method. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(10): 17–23, 2001
Content distributing algorithm for replicated Web servers based on market models
Authors: Nishimura Kenji , Yamamoto Miki , Ikeda Hiromasa 
Published: August 2002

AbstractA content distributing algorithm based on market models for a replication distribution scheme of Web contents is proposed. In general, replication distribution is considered to effectively utilize the time and space local properties of access from a client and has been the topic of numerous studies. However, maintaining QoS (such as shortening the content obtaining time) in replicated servers when servers are in a congested state has not been considered in these studies. Since replicated servers constitute a resource shared by multiple ISPs (Internet Service Providers), the accesses need to be limited to replicated servers in case of a congested state to maintain the QoS enjoyed by each client. Thus, in this paper, a scheme for determining allocation of access to replicated servers for each content during congestion based on market models is proposed. The analytical and simulation results have confirmed that the proposed method controls the QoS in accordance with the access arrival rate to each content. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(11): 9–19, 2001
In‐situ observation of GaAs surface in high vacuum by contact angle measurement
Authors: Matsushita Koichi , Monbara Takuya , Nakayama Ken , Naganuma Hiroshi , Okuyama Sumio , Okuyama Katsuro 
Published: August 2002

AbstractWe developed an apparatus to measure the contact angle formed by a Ga droplet adhering to a GaAs substrate and the GaAs surface to understand the surface state of a GaAs substrate maintained at a substrate temperature in the range of 20 to 550 °C in a high vacuum. The following results were obtained by this apparatus. The contact angle of a Ga droplet on a GaAs(100) substrate with a grown oxide film had the value of 140° in a vacuum independent of the substrate temperature and showed no variation in the wettability. The contact angle decreased as the wettability improved and the substrate temperature increased when the oxide film was removed. Furthermore, the degree of wetting depends on the surface orientation of the GaAs substrate. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(11): 51–59, 2001
Asynchronous current‐mode multiple‐valued VLSI system based on two‐color two‐rail coding
Authors: Hanyu Takahiro , Kameyama Michitaka 
Published: August 2002

AbstractIn deep submicron VLSI, the asynchronous data protocol is a known technique to solve the performance degradation and increase in power dissipation problems arising from wiring such as cross queues. In this paper, we propose a new asynchronous multiple‐valued data communication scheme without rest phases in multiple‐valued data transfers. This scheme uses two‐railR‐value complementary signal pairs, and the sum of the two‐rail signal pair is always a constant for “valid data.” Along with defining a two‐rail signal pair with each signal having an odd phase or an even phase, each signal level in the even phase is set to always be larger than in the odd phase. The sum of a two‐rail signal pair becomes the minimum and the maximum, respectively, of the odd phase and the even phase. Consequently, if the sum of the two‐rail signal pair is examined, the monotonicity can be maintained in data transitions in two phases, and valid data can be detected by a simple threshold calculation. Furthermore, an asynchronous control circuit layout based on the linear sum of a two‐rail signal pair focuses on “the ability to implement the linear addition of current only at the connections” and clearly shows the ability to implement a more compact system than current‐mode multiple‐valued circuit systems. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(11): 60–67, 2001
Scattering analysis of large‐scale cavities using the nonstandard FDTD method
Authors: Ohtani Tadao , Kudo Hironori , Kashiwa Tatsuya 
Published: August 2002

AbstractThe nonstandard FDTD method has been proposed for highly accurate numerical analysis of large structures. However, the conventional nonstandard FDTD has been defined only with isotropic grids, and hence the treatment of arbitrary cavity shapes has been severely restricted. In order to remove this restriction in this paper, the nonstandard FDTD method is extended to more general noniso‐tropic grids. First, the FD Laplacian for the nonisotropic grids is newly defined. From the expression for decomposition by the first‐order difference operator, the nonstandard FDTD equations are derived for nonisotropic grids. The physical meaning of the nonstandard FD method used in the nonstandard FDTD method is clarified. Next, by means of the nonstandard FDTD method extended to nonisotropic grids, a scattering analysis of large‐scale cavities is performed and its effectiveness is demonstrated. The results obtained by the nonstandard FDTD method agree well with the measured values, confirming that the nonstandard FDTD method is effective as a highly accurate scattering analysis method for large‐scale cavities. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(12): 8–16, 2001
Speeding up multiagent reinforcement learning by coarse‐graining of perception: The hunter game
Authors: Ito Akira , Kanabuchi Mitsuru 
Published: August 2002

AbstractReinforcement learning is a promising technique for making agents learn to cooperate in the real world. When we try to apply the technique to a practical problem, however, the slowness of learning due to the increased number of states becomes a bottleneck. We try to speed up learning by reducing the effective number of states by coarse‐graining of perceptions at the early stage of learning, and at the same time try to ensure the overall performance by switching back to complete perception later. By only switching the perception granularity, however, it is difficult to rectify bad habits acquired at the early stage of learning. Hence, we make a coarse‐grained perception learner and a complete perception learner work in parallel, and switch the learner used for action selection at an appropriate time. This technique makes possible both fast early‐stage learning and overall good performance. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(12): 37–45, 2001
Finding all solutions of piecewise‐linear circuits by using linear programming
Authors: Yamamura Kiyotaka , Tanaka Shigeru 
Published: August 2002

AbstractAn efficient algorithm is proposed for finding all solutions of piecewise‐linear (PWL) resistive circuits using linear programming (LP). This algorithm is based on a simple test (termed the LP test) for nonexistence of a solution to a system of PWL equations of the formPg(x) +Qx–s= 0 in a given region. In the LP test, the system of PWL equations is transformed into an LP problem, to which the simplex method is applied. Such an LP problem is obtained by surrounding the PWL functions by rectangles. In this paper, it is shown that the LP test can be performed very efficiently mostly by Phase II of the simplex method. Using the proposed techniques, the number of pivotings in the LP test becomes much smaller, which makes the algorithm very efficient. By numerical examples, it is shown that the proposed algorithm could find all solutions of relatively large scale circuits (including those where the number of variables is 200 and the number of linear regions is 10200) in practical computation time. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(7): 1–11, 2001
Calculating the upper bound of the Multiple‐Choice Knapsack Problem
Authors: Nakagawa Yuji , Kitao Masachika , Tsuji Mitsuhiro , Teraoka Yoshinobu 
Published: August 2002

AbstractAn upper bound or a lower bound of the Multiple‐Choice Knapsack Problem can be calculated by solving LP relaxation. In 1979, Sinha and Zoltners proposed a branch‐and‐bound algorithm for solving the Multiple‐Choice Knapsack Problem, and provided a method to obtain the strict upper bound. In this paper, we propose a new calculation method to obtain a stricter upper bound than the upper bound of Sinha–Zoltners and compare the results of the two methods. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(7): 22–27, 2001
Precise interpolation for band‐limited digital signals based on sampling theorem incorporated with window functions
Authors: Asai Takahiro 
Published: August 2002

AbstractThis paper proposes an interpolation method called the “window function method” in which the sampling theorem and the window functions are combined. The cause of the generation of the interpolation error is the folding distortion due to the multiplication of the time‐limited window to the input signal. The conditions to enable precise interpolation are that the functions are continuous, the windows with large spectral decays in the side lobes are normalized such that the window function values are unity at the interpolation points, and the main lobe width is set to an optimum. When the interpolation precision is compared with those by other interpolation methods, the present one is about the same as that in the “filter method” (the conventional method using the filter to eliminate the unwanted image components) but is somewhat poorer than that in the “least RMS error method” (theoretical limit) if Kaiser–Bessel windows are used. However, the number of input signal data to obtain the same interpolation precision is larger only by 10%. Hence, the operating time to obtain the required interpolation precision is close to optimum. The calculation of the coefficients needed for interpolation is basically a simple substitution and can avoid a design of higher‐order filters (in the filter method) and solution of the ill‐conditioned simulation equations (in the least RMS error method). © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(7): 63–77, 2001
Development of template matching hardware and its high‐speed processing strategy
Authors: Muramatsu Shoji , Kobayashi Yoshiki , Takahashi Kazuya , Shimizu Eiji 
Published: August 2002

AbstractThe template matching technique is now applied to tracking of outdoor object and position measurement, and there is increasing demand for application of template matching based on the normalized correlation coefficient, which is robust against the variation of illumination. In order to apply the technique based on the normalization technique to practical application problems, however, high‐speed calculation of the normalized correlation coefficient is required. This paper intends to improve the speed by implementing by hardware the calculation of the normalized correlation coefficient, which requires a large amount of computation. The proposed method decomposes the normalized correlation coefficient calculation into five operational components, each of which is implementated by hardware. The speed of processing is improved being combined with a parallel processing with a high degree of freedom based on the local property owned by the template matching process. For further improvement of the speed, the application of the pyramid structure is considered. Hardware that can handle the pyramid structure is realized. An evaluation was tried using an actual machine. The performance of the developed hardware is evaluated. The effectiveness of the approach is verified by applying the method to the traffic flow measurement system, as an example of an actual outdoor system. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(11): 1–10, 2001
On selection rules for database compression using KDD
Authors: Aisaka Kazuki , Tsukamoto Masahiko , Harumoto Kaname , Nishio Shojiro 
Published: August 2002

AbstractDespite the drop in disk prices in recent years, the costs associated with disks still represent the primary costs for large‐scale databases such as those used in data warehouses. Compression and storage of such databases is seen as an effective means to reduce these costs. The authors' research group has already proposed a compression method that exchanges the priority for rules and data after extracting rules latent in data by using knowledge discovery as a database compression method which can access a database in its compressed state. However, this proposed method has the problem of producing differences in the compression ratio due to the priority with which the extracted rules are used for compression. Simply finding all the combinations for the priority for the use of such rules is not practical, and so in this paper the authors propose a rule selection method which provides comparatively good compression ratios without excessive computational requirements, then demonstrate the validity of their method using experimental results. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(11): 11–20, 2001