bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability considerations and dynamic control in csma packet radio networks
Authors: Mukumoto Kaiji , Fukudas Akira 
Published: July 2007

AbstractSo far, many proposals have been put forward for increasing the channel capacity of the ALOHA system. Among these is the use of the CSMA system which is known to improve to a great extent the properties of the random access system by ground radio or cable. So far, the slotted CSMA system has been studied in detail for its dynamic characteristics and traffic control effect. But in the case of non‐slotted CSMA, except that its capacity is almost the same, a detailed analysis has yet to be done. In this paper, the dynamic characteristics of the non‐slotted CSMA due to ground radio has been investigated by equilibrium point analysis. It is revealed that the throughput characteristics of the non‐slotted CSMA system are almost similar to those for the slotted CSMA system, but the system stability is quite poor. Next it is proposed that a simple traffic control be applied in the non‐slotted CSMA and the improvement in stability has been studied. It is shown that the dispersion of the packet delay is increased slightly but the operation due to this simple control system can be made sufficiently stable. Thus it is shown that it is not necessary to apply the complex terminal control, i.e., synchronizing the transmission with the slot, for the system stability.
Analysis of oscillation characteristics and design of a plate‐type impatt oscillator
Authors: Chiang Tai‐Ho , Suemune Ikuo , Fukushima Makoto , Yamanishi Masamichi , Kawanos Tadsu 
Published: July 2007

AbstractThe admittance of an IMPATT‐diode pellet is calculated by a large‐signal analysis and the equivalent circuit parameters of the diode package are obtained by measurement. The operating characteristics of a rectangular‐plate‐type IMPATT‐diode oscillator are measured and compared with those obtained analytically employing the diode admittance and are almost in good agreement with the experimental ones.A stepped‐plate‐type IMPATT‐diode oscillator is proposed and designed by the aid of a computer. The oscillation frequencies and the output powers of the constructed oscillator are almost in good agreement with the designed ones.
An automatic equalizer using block‐iterative algorithm
Authors: Sakaniwa Kohichi , Yokoyama Hiroshi 
Published: July 2007

AbstractThis paper presents an automatic equalizer consisting of transversal‐type circuits which uses a block‐iterative algorithm for tap‐gain adjustment. The taps of an FIR filter are divided into groups. The proposed algorithm seeks the optimum tap gain for each group in one step. This algorithm may be regarded as an extension of the Gauss Seidel algorithm, which is a solution method for first‐order simultaneous equations. Unlike the ordinary steepest‐descent method, it is guaranteed to converge to the global optimum even for transmission lines having totally unknown channel distortion. Computer simulations reveal that the block‐iterative algorithm, by allocating two to three taps in a group, converges faster than the ordinary steepest‐descent method and requires fewer computational steps.
Tube‐contacted slab dielectric waveguide for millimeter waves
Authors: Gomi Jun , Yoneyama Tsukasa , Nishida Shigeo 
Published: July 2007

AbstractIn this paper, a tube‐contacted slab dielectric waveguide for millimeter waves is proposed, and a theoretical analysis and experiments are performed to determine the propagation characteristics. This waveguide consists of a dielectric tube with its radius larger than the wavelength, placed on a guiding film. The guided wave energy is concentrated near the contact point between the tube and the film. Since the tube is easily bent due to its structure and the field distribution is similar to Gaussian, the structure can be used as a low‐dispersion flexible dielectric waveguide. Also, since the tube radius is larger than the wavelength, the waveguide can be used for high power transmission. The effective dielectric constant method has been used for analysis, and the field distribution and the phase constant have been computed. A waveguide has been fabricated for 35 GHz and the field distribution, propagation loss, guide wavelength, the field distribution at a bend and the bending loss have been measured. Measured results of the field distribution, guide wavelength and bending loss have agreed well with theoretical predictions. The propagation loss is 1.52 dB/m. In addition to the bending loss, variations of the field distribution at the transition from the straight guide to the bend have been measured. Based on these measured results, it is shown that the waveguide can be used for low‐dispersion flexible transmission line or for high power transmission.
Investigation of a low spurious noise frequency synthesizer using a two‐stage sample‐and‐hold phase comparator
Authors: Yamashita Kiichi 
Published: July 2007

AbstractIn the low spurious noise frequency synthesizer used in communication or measuring equipment, a ripple‐suppression filter with a high attenuation is required to suppress the noise in the phase comparator. This filter, however, often causes instability in the phase‐feedback loop because of its large group delay. An analysis is made of the noise of the sample‐and‐hold phase comparator, which is suited to the low spurious‐noise frequency synthesizer, and it was found that a dip‐type noise is always produced in the sampling period together with the sag noise. This phenomenon was not recognized in the past. It is shown that this is the major source of the spurious noise, and a ripple‐suppression filter with an attenuation of several tens of dB is required to realize a spurious noise level of ‐85 dB or less to meet the system specification. Then, based on the results of the noise analysis, a two‐stage sample‐and‐hold phase comparator is proposed; sampling of the second stage is initiated immediately after sampling of the first stage is completed. It is shown that the noise is thus drastically reduced. Finally, it is shown that with this new phase comparator a low spurious‐noise frequency synthesizer can be realized without using the noise‐suppression filter.
Precoded and polarity‐controlled 3B‐2T code transmission systems
Authors: Ohue Kenji , Yoshikai Noriaki , Yamaguchi Haruo 
Published: July 2007

AbstractIn realizing block polarity controlled 3B‐2T code transmission systems, suppression of burst error occurrence due to block polarity control for BSI is the most important problem. This system is more efficient then the conventional AMI code transmission and 4B‐3T code transmission systems. This paper describes a new polarity‐control method, PPC, which makes it possible to eliminate burst errors, and the 3B‐2T code transmission system construction using this method. The proposed polarity‐control burst error elimination is realized by precoding and decoding for polarity indicating signal sequence, and inserting dummy bit at the head of polarity‐control block.The characteristics of twenty‐four 3B‐2T code conversion rules and the four optimum 3B‐2T code conversion rules with average error extension rate 1.6 and average parity detection rate 1.0 are shown. Moreover, word synchronization at demodulation is achieved by detecting the ternary illegal word and its average synchronization detection digit length is shown to be 16. The optimum polarity control block length for an 800 Mbit/s coaxial PCM transmission system is determined to be 32 digits, considering SN degradation caused by waveform distortion due to low‐frequency‐cutoff, timing information disappearance and scapegoat bit insertion which are introduced to satisfy BSI condition.
Efficient energy transfer dye lasers in spectral region of near ultraviolet to violet
Authors: Muto Shinzo , Ito Regular Chiaki , Inaba Humio 
Published: July 2007

AbstractAn experiment was performed on the operation and development of energy transfer dye lasers (ETDL), using scintillator dye mixture to obtain higher efficiency and an expanded range of wavelengths in the ultraviolet to violet region, in which an N2 laser is used for excitation. High lasing efficiencies were observed with αNPO‐dimethyl. POPOP, PPF‐αNPO, and some other dye mixtures, and overlapping lasing was observed, involving the donor and acceptor dye laser regions. A blue shift of the oscillation frequency was analyzed theoretically, and the theoretical results concerning the dependence of the oscillation wavelength on laser power and donor dye concentration were in good agreement with observations.
Control of a‐Si FETs characteristics by impurity‐doping
Authors: Sugiura Osamu , Matsumura Masakiyo 
Published: July 2007

AbstractThis paper reports the study on characteristics control of amorphous silicon field‐effect‐transistors (a‐Si FETs). For the application of a‐Si FETs to switching elements in the display panel, it is necessary to have enhancement‐type transistors. To do so, the impurity‐doping method is investigated. First, a numerical analysis considering the localized states was carried out. It was shown that the characteristics control of a‐Si FETs, such as single‐crystal Si MOS FETs, can be achieved by impurity doping. Next, practical a‐Si FETs were fabricated with phosphorus doping or boron‐doping into the channels of transistors. Characteristics of these transistors were investigated and characteristics control was shown. Characteristics of the phosphorus‐doped transistor as well as characteristics of boron‐doped p‐channel transistors showed the same properties as have been predicted by numerical analysis. By contrast, at the boron‐doped transistors, characteristics of n‐channel operation were deteriorated even at a small concentration of boron‐doping. This is due probably to a large variation of the localized state density by boron‐doping.
Programmable generation of nonlinear cyclic shift sequences
Authors: Tanaka Mamoru , Ozawa Shinji , Mori Shinsaku 
Published: July 2007

AbstractThis paper proposes a nonlinear feedback shift‐register system Rn composed by combining a memory with an n‐stage shift‐register. A new method for generating a nonlinear binary cyclic shift sequence of length T (1 ≤ T ≤ 2n) which can be generated by the proposed system is discussed using a binary graph Gn corresponding to the state transition of the system Rn. As a first step, the number of sequences is briefly discussed. It is then shown that a sequence of length T that can be generated by the system Rn can also be generated by extending the traditional Scholtz algorithm to determine the non‐degenerate cyclic equivalence classes of length T. Then a method of generating a de Bruijn sequence of length 2n without using Boolean function is proposed which corresponds to the Hamilton directed loop in the graph Gn. The method consists of converting the initial n‐th order Hamilton directed loop to another n‐th‐order Hamilton directed loop and requires less memory capacity than the traditional method that determines the next n‐th‐order de Bruijn sequence by utilizing all of the (n‐1)‐th order de Bruijn sequences. The method is effective since the conversion procedure is easy. Because of the greater number of sequences generated and the programmable property of the sequence conversion, the method can be expected to be applicable to spread spectrum communication.
Topological properties of sequential network analysis
Authors: Ozawa Takao , Yamada Masaaki 
Published: July 2007

AbstractSequential network analysis is a method of analyzing a network by choosing some independent variables among the unknown variables in the network, expressing the remaining unknown variables sequentially in terms of the independent variable by applying KCL and KVL, and then solving the constraint equations obtained as the result of the sequential process to determine the independent variables. This paper deals with the topological properties of a sequential analysis formulated for an active network. The network topology is represented by current‐ and voltage‐graphs. The set of edges whose unknown variables are chosen as independent variables is called the independent‐edge set (denoted by Eb), the set of edges at which the constraint equations are obtained is called the constraint‐edge set (denoted by Eu), and the set of edges whose unknown variables are expressed in terms of the independent variables is called the covered‐edge set (denoted by Eβ). The sequential step of the analysis proceeds by repeatedly adding to Eβ an edge which is current‐dependent and/or voltage‐dependent with respect to Eβ. Thus a sequence of covered‐edge sets is obtained. The conditions for current‐dependent, voltage‐dependent, independent and constraint edges are presented and the duality among them is also clarified. From the sequence of Eβ a sequence of Eβ U Eb ‐ Eu is obtained. Each of the sets in this sequence specifies the electrical connectivities between Eb and Eu. The relation between the edge sets defined above and the structure of 2‐graphs is given. Finally, minimum independent‐edge sets are given for some special types of graphs, and an algorithm to decrease the number of independent edges is presented.
Error rate performance of dpsk signal in land mobile radio with predetection diversity combiner
Authors: Miyagaki Yoshiya , Morinaga Norihiko , Namekawas Toshihiko 
Published: July 2007

AbstractThe symbol rate of an M‐ary DPSK signal, caused largely by inherent high irreducible error in the delay detection system, will be discussed for the case of applying the diversity‐combining reception under high‐speed Rayleigh fading in land mobile radio systems. As for the predetection combining methods of the L‐branch, which comprise selective combining iso‐gain combining and the maximum ratio combining, we will demonstrate anew that both error rates, caused by the envelope fade and random‐FM can be represented entirely by L‐square of the error rate in case of no diversity combiner. Particularly, our analysis centers on improvement of random‐FM. We conclude that the L‐square improvement could be applied to the random‐FM similar to the envelope fade and, further, the optimum combining system which minimizes the random‐FM is also maximum ratio combiner. This report will be helpful in doing comparisons among systems, because it shows that the error rates of M‐ary DPSK with the diversity reception characteristics could be represented in a thorough and understandable form.
Long‐term high‐vacuum maintenance in the sealed cryogenic cable envelope for superconducting telecommunication cables
Authors: Hikita Makoto , Yoshikiyos Haruo 
Published: July 2007

AbstractTo obtain the high performance of a cyrogenic cable envelope employing multilayer vacuum insulations, it is necessary to maintain the presence between layers under 10−2 Pa. To investigate the possibility of long‐term high‐vacuum maintenance of a sealed cryogenic cable envelope containing adsorbents, we have cooled a 2‐m cryogenic envelope to a liquid nitrogen temperature and made a degassing analysis and degassing rate measurements. We found that the main degassing component was N2 and the degassing rates were at 10‐2 to 10‐3 Pa. We have also cooled a coconut‐shell charcoal to the liquid nitrogen temperature and obtained the N2 adsorption amounts. Based on the above results, we obtained the following conclusion. In a cryogenic cable envelope with an external diameter 70 mm in which Al is used as an outer pipe and the nitrogen shield pipes are stored inside, if we can realize the ultimate pressure below 10‐3 Pa, it is possible to have a durability life of over 20 years at a pressure below 10‐2 Pa by placing about 1 g of coconut‐shell charcoal per 1 m on the circumference of the liquid nitrogen shield pipe.
Design of 6‐port compensating circuits for circulators
Authors: Ikeda Akihiro , Araki Kiyomichi , Naitos Yoshiyuki , Iwakuni Mikio 
Published: July 2007

AbstractThe authors first proposed, for circulators, the 6‐part compensating circuit synthesis method taking into account the interpart couplings. On using the 6‐part compensating circuit, any incomplete lossy circulator can be transformed into a completely matched and isolated circulator. The circulator, after being compensated, will have its transmission coefficient determined uniquely by the circulator characteristics alone. The transmission coefficient can be taken as the suitable figure of merit of the circulator and as an invariant quantity for analysis.In this paper the practical circuit structure of the 6‐part compensating circuit is shown and its design method clarified. The general design method will be discussed first, followed by that which is simplified by use of less elements. Based on this a 200‐MHz band compensating circuit is fabricated and its design soundness is confirmed.
Detection with net‐structure arrays of Josephson Junctions
Authors: Fujimaki Norio , Okabes Yoichi , Okamura Sogo 
Published: July 2007

AbstractSeveral studies have been performed on fabrication of Josephson junction arrays to improve the voltage sensitivity and impedance matching of Josephson junctions to be used as high‐speed and high‐sensitivity detectors of microwaves and submillimeter‐waves. This paper proposes a method for arranging point‐contact Josephson junctions in a net structure and describes experimental results of detection. First, we measured the I‐V characteristic at super low temperature and found that the critical current can be adjusted from a few μA to a few mA by varying the contact pressure. Next, we obtained the equivalent circuit of this net‐structure array installed in an x‐band waveguide in such a way that the array is perpendicular to the wave traveling direction. The net‐structure array was treated as a uniform surface impedance and the series admittance due to the gap between the array and the waveguide wall was obtained by an extension of the analysis for a capacitive window. To compare the equivalent circuit parameters with measured values, we carried out an impedance measurement at room temperature. The results agreed well with theoretical values. Further, a preliminary experiment for a wideband detection was performed in the superconducting state and obtained detection voltages for 10‐GHz signals as well as HCN laser light of wavelength 337 μm.
Residual stresses in optical fiber preforms
Authors: Edahiro Takao , Jinguji Kaname , Shibata Noriyoshi 
Published: July 2007

AbstractThe optical fiber consisting mainly of quartz glass comprises a number of different kinds of glass having different constituents. Therefore, as is widely known, there are residual stresses left in the optical fiber preforms and the fiber itself which are caused by the difference of thermal expansion coefficients. To clarify the effect of the residual stress on the optical performances of the optical fiber, a measurement was carried out on the residual stresses of the optical fiber preforms and the fiber in a vertical plane normal to the longitudinal axis by means of optoelastic effect. Then the variation due to different thermal hysteresis and dimensions, influence of GeO2 addition concentration in the core and the effect of different refractive index were studied. As a result, it was revealed that the thermal hysteresis during drawing almost did not influence the residual stress distribution. The residual stress increased depending on the increase of additive concentration and its tendency agreed well qualitatively with a theoretical forecast. The residual stresses had such an influence on the refraction index decrease that with respect to the quadratic distribution of 1% relative refractive index difference between core and clad, the refractive index decreased by approximately 3.9 × 10‐4, Also, it was made obvious that the effect of residual stresses could not be disregarded for more precise refractive index control.
Computer simulation of respiratory control system
Authors: Suzuki Naoki , Uchiyamas Akihiko 
Published: July 2007

AbstractThe respiratory system in a human body is a control system for maintaining the stability of the body against the variations of the external environment. In the system, the gas concentration in the alveoli and the blood play an important role as a source of information. A computer simulation of the respiratory system is performed based on a model in which the diffusion phenomenon and the gas transportation delay are incorporated. Also, analyses of the response of the system to a variation of the control mechanism as well as of the overall inspired gas components in the system are conducted. The simulation model used in this paper is largely composed of two components, i.e., the control system itself and several kinds of body tissues, representing a whole body. The system to be controlled is the vascular circulatory system which connects the lungs, the brain and the body tissues. O2, CO2 and N2 are carried through the system. On the basis of this fact, the external respiration in the lungs and the internal respiration in the body tissues can be expressed by equilibrium functions, representing the gas exchange by the diffusion phenomenon, the variation of hydrogen ion concentration in the blood, and the quantity of oxidized hemoglobin. Utilizing the model, the variation of the respiratory system in response to the inspiration of air lacking O2 as well as to the possible damage occurring within the system are investigated.
Identification of an unknown pattern asynchronously generated in noise
Authors: Kikkawa Sho , Murata Tatsuhiko 
Published: July 2007

AbstractThis paper discusses the identification of an asynchronously generated unknown pattern buried in stationary noise. The historical background of the problem is described and it is pointed out that the existence in principle of a solution of this problem is not known. The statistical moment function of the ensemble of observation is defined in the frequency domain and the discussion is carried out in the frequency domain. The pattern is represented in the frequency domain in polar coordinates, and identification is attempted separately for amplitude and phase. The unknown pattern is shown to be identified by utilizing information on the first and the second moment functions of the samples. It is shown that the amplitude term of the solution can be represented quite simply for white noise. It is further shown (even when the noise is not white but is normally distributed) that the amplitude term of the solution can be represented relatively simply by using the third‐order moment function of the sample. It is shown that the phase term of the solution is given as a solution of a certain system of equations. When the characteristic function of the probability density of the fluctuation in position of the pattern is a positive real function, the representation becomes simple by using the first‐order moment function of the sample.
An analysis of unbounded field problems by finite element method
Authors: Washisu Shin , Fukai Ichiro , Suzuki Michio 
Published: July 2007

AbstractIn recent years, the finite element method has been used widely in the field of electrical and electronics engineering. This method is applied mainly to bounded fields with specified boundary conditions. In practice, however, there are many problems dealing with unbounded fields. Several attempts have been made to solve these problems by using free‐space Green's function. Some of them are advantageous in eliminating singularities of Green's function. However, these methods do not produce good calculation result. This paper proposes a new modified finite‐element method which is effective in solving the unbounded electrostatic and electromagnetic‐field problems. This method is applied for the analysis of the field distribution near the open end of the parallel‐plate waveguide.