bluuebunny/crossref_metadata_2025 huggingface dataset:
Postdetection selection diversity effects in a digital fm land mobile radio with discriminator and differential detections
Authors: Adachi Fumiyuki
Published: July 2007

In the digital FM land mobile radio communication with fast fading whose maximum Doppler frequency reaches several ten Hz, the error occurs due to the signal amplitude variation and random FM noise caused by the phase variation. This paper discusses the performance improvement by the postdetection selection diversity for the digital FM radio communication with discriminator and differential detections under a fast Rayleigh fading environment. The conditional error ratio is derived for the instantaneous detector input amplitude at fast Rayleigh fading and the average error rate at the diversity reception is obtained as a general solution with the effect of random FM noise taken into account. Further, the improvement effect in the presence of co‐channel interference is analyzed. The comparison is made with the postdetection synthesis diversity.
Residual stresses of fibers in tape‐type optical cable and their reduction
Authors: Yamauchi Ryozo , Inadas Koichi , Ishihara Koshi
Published: July 2007

When the tape‐type optical fibers are twisted or cabled, longitudinal stress is generated in the fibers. This stress has been discussed solely as a practical problem on the stress generation among the tape‐type fibers. In this paper, a practical model is set up and calculation is conducted for the stress generated in the fibers of a tape‐type optical cable. Under the practical condition of normal tape cabling, the main stresses generated on the fiber surfaces are governed by the twists appearing on the individual fibers. The direction of the main stress caused by the twist is different from the stress direction by the conventionally applied screening strength test. Accordingly, it is needed to apply screening to the fiber elements in a tape‐type cable under more intense tensile stress. To reduce the fiber stresses generated by the fiber tape cabling, we propose a “pre‐twisting method” where the fibers are pretwisted in the opposite direction to that of tape cabling, thereby cancelling the cabling stresses. Its effectiveness has been made clear by the experiment.
Dynamic characteristics of the improved forward‐type multiple‐output dc‐dc power converter using cross regulation
Authors: Matsuo Hirofumi , Kurokawa Fujio
Published: July 2007

The conventional forward‐type multiple‐output dc‐dc converter has a deficiency in that when the output load current drops below a certain value, and the reactor current becomes discontinuous, or when the load changes dynamically, the cross‐regulation function is lost.

The authors previously proposed a means to improve the steady‐state characteristics via a forward‐type multiple output converter in which magnetic couplings of windings in the transformer and reactor are utilized.

In this paper, the improved forward‐type multiple‐output converter was studied including analysis of its dynamic characteristics. First, the steady‐state characteristic was analyzed. Second, the dynamic characteristic was disclosed in which it was shown that, due to the magnetic coupling between reactor windings and P‐D feedback control, a dynamic cross‐regulation function was obtained and even when the smoothing capacitors are relatively small, the variations of output voltages on load change are well suppressed. Further, comparisons were made with the conventional forward‐type multiple‐output converter and the superiority of the improved circuit was clearly shown.
Preparation and characteristics of PBF2‐ALF3 and PBF2‐ZRF4 glasses
Authors: Shibata Shuichi , Kanamoris Terutoshi , Mitachi Seiko , Manabe Toyotaka
Published: July 2007

It was found that PbF2‐AlF3 and PbF2‐ZrF4 form glasses. Glass forming regions are 30 ≤ AlF3 ≤ 60 and 40 ≤ ZrF4 ≤ 60 (mol.%). Glasses are prepared by the casting quenching technique or the roller quenching technique. Both glass systems have transmission windows in 0.3 to 9 μm wavelength region with a minimum loss band at 3 to 4 μm and are expected to have a loss of less than 0.1 dB/km.

The infrared absorption edge is determined by the absorption band of AlF3 or ZrF4. The refractive index is about 1.6 to 1.7 and decreases as the amount of AlF3 or ZrF4 increases. Therefore, it is possible to design a propagation structure by controlling the amount of AlF3 or ZrF4. Their crystallization temperatures are in a range of 250 to 400°C and increase as the amount of AlF3 or ZrF4 increases. The crystallization temperature of PbF2‐AlF3is higher than that of PbF2‐ZrF4.

The activation energy of crystallization is about 80 kcal/mol and therefore, is thermally stable at room temperature. Because of these results, PbF2‐AlF3 and PbF2‐ZrF4 glass systems are promising optical fiber materials for the 3‐4 μm wavelength region. Furthermore, it becomes clear that the quenching technique is an important method for making glasses from various crystals.
Cross‐correlation speed measurement using itv camera
Authors: Nagai Keinosuke , Akazawa Hideo , Idogawa Tohru
Published: July 2007

A new method for speed measurement by correlation techniques is proposed. An image of a rough surface of a moving object is obtained every 1/30 second using an ITV camera with a rotary shutter. The displacement of the object during 1/30 second is estimated from a polarity cross‐correlation function between two successive surface images. (1) The speed v to be measured is proportional to the displacement. (2) v = O can be measured. (3) The average length for the computation of correlation function is determined from the measurement accuracy required. The time required for signal processing is less than one field period (1/60 second).
Solid‐state inductors by gic
Authors: Nakamura Masataka , Shigehiros Takanori
Published: July 2007

The solid‐state inductor is realized using the GIC which has the voltage‐current relations E1 = E2 and I1 = I2/Jτ at the input‐output terminals. The present GIC is composed of three transistors and suffers from the parasitic oscillation at high frequencies. This parasitic oscillation is prevented effectively by creating the transmission zeros in the loop circuits. The Q deterioration can be compensated by adding a series circuit of capacitance and resistance.

The experimental inductor has the temperature coefficient 500 ppm/°C up to 1 MHz and is highly stable (high Q). Several GIC's can be cascaded with stable supply of the dc bias. This GIC is applied to bandpass filters (center frequency 455 kHz, bandwidth 21.4 kHz).
Asymptotic behavior of nonlinear discrete‐time compartmental systems—comparison with continuous‐time systems
Authors: Fukui Ayumu , Maeda Hajime , Kodama Shinzo
Published: July 2007

This paper derives the difference equation for nonlinear compartmental systems by means of the forward Euler method and compares the solution of the continuous‐time compartmental system with the solution of the system by the difference equation. That is, the objective of this paper is to derive the conditions under which the discretized system created by difference equation preserves the specific properties of the original continuous‐time compartmental systems (non‐negativity, monotony and non‐oscillatory properties of the solutions) and the admissible range of the step width in the difference equation. It shows that the uniformly bounded solutions with constant input can be approximated uniformly in [0, ∞) by the solutions of the difference equation with arbitrary small errors. Furthermore, it derives the condition under which the accumulated round‐off errors become uniformly bounded for uniformly bounded round‐off errors.
Design of new predictor using covariance information and its application to prediction of air pollution levels
Authors: Nakamori Seiichi , Hatajis Akira
Published: July 2007

This paper presents a new, linear continuous predictor based on innovation theory using covariance information on data to be predicted as a statistical non‐physical model. Model simulation is performed to investigate the effectiveness of the proposed predictor. The predictor obtained for the case when observed noises are stationary white + colored noises is seen to exhibit reasonable prediction and white noise characteristics. As its practical application, the predictor is used to predict SO2 levels and the SO2 data thus obtained is compared quantitatively against the prediction by conventional auto‐regressive model based on MEM. As a result of experiments, the effectiveness of the predictor is assumed.
256‐bit elastic store cmos LSI
Authors: Fukuda Hideki , Yasukawa Hiroshi , Ohwadas Norihiko
Published: July 2007

This paper reports the design and characteristics of the 256‐bit elastic store (ES) CMOS LSI. The elastic store circuit absorbs phase differences of signals and is one kind of First‐In‐First‐Out (FIFO) Read/Write memory with the function of application to multiplex. The circuit is equipped with an elastic function which can perform write and read of the data independently and other functions such as reset and inhibit of the address counter and phase comparator. As CMOS circuits, NAND gate at store cell and D‐F/F with reset terminals at address counter are used to obtain stabilization, high‐speed operation and low‐power consumption. As the result of a prototype LSI, a performance at more than 9 MHz under the worst condition of VDD = 4.75 V and Ta = 70°C and the characteristics of high speed and low power consumption of 125 mW have been obtained. Its possible application to various equipment for digital network in PCM secondary group is discussed.
Fine pattern technology for multilevel metallization with piq insulation
Authors: Saiki Atsushi , Mukai Kiichiro , Haradas Seiki , Okubo Toshio
Published: July 2007

PIQ (patented) is known to be a very effective polymer for use in planar multilevel interconnection technology. To realize fine patterns and a high order of integration of this technology, we studied a wet‐etching mechanism with an etchant based on hydrazine hydrate. Hydrazine hydrate is known to be an etchant for the PIQ, as are also NaOH and KOH. However, hydrazine hydrate is not suitable for fine‐pattern technology because it causes a region of swelling in PIQ film. We analyzed the swelling region by infrared spectroscopy and found that ethylenediamine solves the swelling quite effectively. Based on these results, we developed a new etchant containing hydrazine hydrate and ethylenediamine. The new etchant enables the creation of stable 3 μ2 via‐holes in the PIQ film. The electrical properties of these holes are also found to be quite good.
Consideration on fine‐patterning techniques in eb lithography
Authors: Sugiyama Naoshi
Published: July 2007

The corrections on the beam distortion and proximity effect in the electron‐beam lithography are discussed from the viewpoint of computer processing. The coefficient parameters of the beam‐deflection‐distortion mapping function are estimated by the least square method from the measurement data of the beam deflection distortion, and the error distribution is clarified. The measurement errors in the movement and rotation of the sample desk are minimized. For the proximity effect correction at the rectangular beam illumination, the illumination intensity distribution function is approximated to the trapezoidal form and the computer simulation is made for the calculation of the exposure dose. Finally, the dependences of the beam scanning direction and the scanning interval on the proximity effect are examined by computer simulation.
Analysis of a binary quantized dpll by equivalent analog model
Authors: Kurita Taiichiro , Mori Shinsaku , Ozawas Shinji
Published: July 2007

A binary quantized digital phase‐locked loop (DPLL) is a class of digital PLLs having advantage of its simplicity and high reliability. This class of DPLL has been analyzed by applying Markov theory. However, this method has a limited range of applications and the numerical solutions of the performances have not been obtained without using a computer. In this paper, a binary quantized DPLL is analyzed by replacing the DPLL with the equivalent linear and nonlinear analog PLL. This equivalent method of analysis can be applied to more general cases. The numerical results agree with those of experiments.
Stability considerations and dynamic control in csma packet radio networks
Authors: Mukumoto Kaiji , Fukudas Akira
Published: July 2007

So 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

The 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

This 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

In 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

In 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

In 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

An 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

This 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

This 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

Sequential 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

The 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

To 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

The 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

Several 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

The 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

The 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

This 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

In 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.
A composite sinusoidal model applied to spectral analysis of speech
Authors: Sagayama Shigeki , Itakura Fumitada
Published: July 2007

A new technique of speech analysis based on a composite sinusoidal model is proposed. In this model, parameters (frequency and intensity of each sinusoid) are determined such that the lower‐order autocorrelation functions of the finite number for the reference signal (a sum of several sinusoidal waves) is equal to those for the observed speech signal. The model is classified into four types: (1) the frequencies of the sinusoids are free; (2) one frequency is fixed to 0; (3) one frequency is fixed to π; and (4) two frequencies are fixed to 0 and π. For all of these, the parameters are solved easily by the basic algebraic method. While the problem is essentially related to the theory of orthogonal polynomials, it is proven that the roots exist if only the autocorrelation function is a positive definite matrix. The efficient algorithm is introduced. Itakura's theory of line spectral representation of linear predictive coefficients can be considered as the conversion theory from the LPC to the composite sinusoidal model. Some experiments of speech analysis are demonstrated. Applications to the speech analysis and synthesis, synthesis by rule, speech recognition, speaker identification, etc., are suggested.
Chromatic spatial frequency response of the human vision—chromatic axes with spatial frequency bandwidth at colored point
Authors: Sakata Haruo
Published: July 2007

A chromatic spatial sinusoidal pattern composed of a complementary color‐pair is displayed on a color‐monitor screen, and, on adding color (saturated Y, M, C and B) to the screen, the color‐difference discrimination threshold for the colored chromatic sinusoidal pattern is determined at low frequency (0.36 cpd) and high‐frequency (3.6 cpd). The direction of the complementary color‐pair, along which the high‐frequency sensitivity decreases most at each color, passes through a point on the u‐axis of the CIE u v chromaticity diagram and almost coincides with the color‐confusion locus of the third color‐abnormal case. On the other hand, the direction of the complimentary color‐pair along which the high‐frequency sensitivity decreases least is almost parallel to the U‐axis. These results indicate that the spatial frequency characteristic of the chromatic channel can be considered to be independent of the average chrominance.
Propagation paths of cyclotron harmonic waves with curvature of geomagnetic field taken into account
Authors: Utsunomiya Toshio
Published: July 2007

The propagation path of cyclotron harmonic waves in the ionosphere and magnetosphere was derived by J. Bitoun. However, the propagation path at low altitude has not yet been investigated. This has been due to the complexity in the analysis in which the curvature of the earth's magnetic field must be considered. In this paper, the propagation path is expressed in a simple equation which considers the curvature of the earth's magnetic field. With this expression, the traveling distance varies depending on the magnetic latitude and altitude of the location of the wave exciter. With the assumed electron density distribution, the corresponding regions in the ionosphere and magnetosphere are clarified. Then the propagation path is calculated with two representative points in these regions. When kX0 > 0, the traveling distance becomes maximum after the reflection point. When kX0 < 0, the effect of the curvature is large, causing a large variation in the traveling distance.
An erasing method of hard magnetic recording media
Authors: Matsumoto Mitsunori , Morisako Akimitsu
Published: July 2007

A two‐step erasing method (dc and ac erasures) is proposed for hard magnetic recording media and test results obtained using experimental erasing heads are presented. The ac erasing characteristics of the commercially available voice‐recording magnetic tapes are measured. The metal tape with 1.06 kOe coercive force requires 2.1 kOe erasing field to obtain 60 dB erasing rate. In the two‐step erasing method, only a 1.2–1.3 kOe field is needed to obtain 60 dB erasing rate for the metal tape when the tape is dc‐erased up to 30 dB. An experimental dc erasing head (permalloy head with 0.08–0.36 mm air gap, 900–3000 windings and 0.81–2.1 mm core width) is fabricated and its dc erasing characteristics are examined. The erasing state is observed by the Bitter method. The gap length of the erasing head must be 1/4 ‐ 1/5.6 of the recording tack width. The effectiveness of the two‐step erasing method is confirmed experimentally.
Nonvolatile memory effects of chalcogenide amorphous semiconductor doped with AG
Authors: Hirose Yooichi , Hirose Haruo , Kunioka Akio
Published: July 2007

With Ag‐photodoped amorphous As2S3 specimens that have nonvolatile memory effect, the electric conduction, temperature and frequency characteristics and thermoelectromotive force are investigated. The fabrication yield of this specimen is almost 100%. This device has a switching function, and the off‐state has a semiconductor type electric conduction with energy gap of 2 eV. The on‐state has metallic conduction and its temperature coefficient is almost the same as that of Ag, 4.0 × 10−3/°C. With a lateral‐type specimen (Au‐Ag electrodes), Ag dendrites are observed under a microscope. The dendrites bridge the two electrodes, resulting in memory action. The bridging of an Ag dendrite played the same role as a crystalline‐amorphous phase change in ordinary semiconductor memory operation.
A new sampling theorem based on the minimum energy principle
Authors: Kishi Genya , Sakaniwa Kohichi
Published: July 2007

Among those low‐pass band‐limited waveforms which take specified sampled values at a specified finite number of sampling points, the one with minimum energy is called the minimum‐energy waveform. This paper first derives the minimum‐energy waveform and strictly proves its uniqueness. Discussion is then devoted to the minimum‐energy waveform which is determined by sampled values of a low‐pass band‐limited waveform of finite energy, and it is shown that the sequence obtained by successively adding sampling points uniformly converges to a low‐pass band‐limited waveform. In general, when a low‐pass band‐limited waveform is uniquely determined from the sampled values at the sampling points, the sampling point sequence is called complete. This paper shows that various kinds of sampling theorems can be derived, by prescribing sampled values for the low‐pass band‐limited waveform for the complete sampling point sequence given by Levinson and constructing the limiting waveform of minimum energy. Especially, a new reconstruction formula is obtained which restores the original band‐limited waveform solely from the past sampled values. It is shown that the traditional Someya‐Shannon interpolation formula can be obtained by specifying particular sampling points in the above restoration formula. The relation between the two formulas is also discussed.
Probability distributions for ratios of fading signal envelopes and their generalization
Authors: Okui Shigehiko
Published: July 2007

This paper describes statistical characteristics of the ratios of fading signal envelopes. The Rayleigh fading is contained as a special case. We derive the ratios of the fading signals following the m distribution, generalized Nakagami‐Rice distribution and generalized Nakagami‐Hoyt distribution. An extension to the case of multiple variable distribution is attempted under some conditions. The results in this paper are given in simple functional forms appropriate for theoretical analysis. The distributions of the ratios of fading signal envelopes can be applied to a wide range of problems of radio wave interference such as evaluation of the ratio of desired signal to unwanted interference signal (DU ratio) and of degradation of cross‐polarization discrimination (XPD) in a microwave transmission channel, determination of frequency reuse distance and of modulation types for mobile communications, and analysis of ratio detection in radar technology.
Generation of defects at Si‐SiO2 interface in electron beam lithography
Authors: Sugano Takuo , Yeh Ching‐Fa
Published: July 2007

It is found that the Si‐SiO2 interface‐state density generated by 25‐keV electron beam lithography does not depend on thickness of the resist. With delineation by a 2‐keV electron beam, interface states are mainly generated by the characteristic × rays, Kα of an Al electrode which the beam strikes. These trapping centers are holes trapped in the interface and they remain when the specimen is annealed in an inert gas at 800°C. However, after annealing in a hydrogen gas at 400°C for 30 min they disappear, but when annealed further in a neutral gas at a higher temperature they reappear. On the other hand, interface states which disappear by annealing in a carbon tetrachloride gas at 800°C for 1 hour, never reappear by annealing at 1000°C in the same atmosphere.
Approximation and construction of the network containing variable elements
Authors: Kawakami Atsushi , Takahashi Shin‐Ichi , Tajima Jun
Published: July 2007

A variable network is a network in which a designated input‐output characteristic can be obtained continuously by varying continuously a specific parameter. This paper describes two methods of approximating the desired variable characteristics by a rational transfer function and constructing it as a concrete network. In the conventional method, an approximation with good accuracy is obtained by raising the orders of the complex frequency s and the variable parameter λ. The actual construction of the network becomes difficult because of the higher orders. Two methods are proposed in this paper to avoid this difficulty. In the first method, the approximated transfer function is divided into unit blocks, lower order for the complex frequency s and a bilinear form for the variable parameter λ. By this method, the actual construction of a network can be simplified considerably. In the second method, the desired characteristics are approximated in the form of a transfer function in which the denominator polynomial is resolved into the polynomials of s and λ, respectively. The approximated transfer function in this form has a merit in that it can be realized with a minimal number of dynamic elements and variable elements in the network construction. Moreover, its stability is independent of λ.
A theory of a nonuniform transmission line and the structure of signal flow
Authors: Ito Chiaki , Sato Risaburo
Published: July 2007

This paper deals principally with the phenomenological description and structural analysis of the signal flow of a nonuniform transmission line and presents a theoretical discussion, including the traditional theories, of the uniform transmission line. Due to the existence of local multiple reflections caused by nonuniformity, the phenomena on the nonuniform transmission line cannot be as clearly described as in the case of the uniform transmission line. The reason for existence of the local multiple reflections, however, is the lack of appropriate selection of the incident and reflected waves from the solutions of the transmission line equation. From such a viewpoint, this paper newly defines the incident and reflected waves as waves obtained by exciting a semiinfinite transmission line in the positive or negative direction. According to this definition, the two waves are not coupled and do not produce the local multiple reflections due to the nonuniformity. Thus, using such incident and reflected waves, a unified analysis can be made for the transmission line, independently of whether it is uniform or nonuniform. At the same time, the signal‐flow structure for such phenomena as reflection, matching and resonance can clearly be described. Using the concept of signal flow, the ultimate expressions for various quantities can easily be reached.
Considerations on diameter of communication networks
Authors: Kurosawa Kaoru , Tsujii Shigeo
Published: July 2007

This paper discusses the relation between the diameter and the number of nodes of a regular graph; also discussed is the relation between a regular graph with minimum diameter and minimal d‐connectivity from the viewpoint of graph theory for the construction of a communication network with high reliability and quality of communication.

First, it is shown that the upper bound of the number of nodes n for given diameter k is Nk−2 in almost all cases, where Nk is Moore's upper bound. Second, it is derived that a regular graph with diameter k and degree d is minimal d‐connected when k ≧ 3 and Nk−d ≦ n < NK or k = 2 and n = N2−2.