bluuebunny/crossref_metadata_2025 huggingface dataset:
The age at diagnosis of type 1 diabetes continues to decrease in Belgian boys but not in girls: a 15‐year survey
Authors: Weets I. , Rooman R. , Coeckelberghs M. , De Block C. , Van Gaal L. , Kaufman J.‐M. , Keymeulen B. , Mathieu C. , Weber E. , Pipeleers D. G. , Gorus F. K.
Published: July 2007

Background

The age at clinical onset of type 1 diabetes is decreasing. Preliminary Belgian data suggested that this anticipation occurred preferentially in boys. We investigated whether this gender‐specific anticipation could be confirmed over a 15‐year observation period.

Methods

In Antwerp, we studied incidence trends between 1989 and 2003 in 746 type 1 diabetic patients under age 40. For 2928 antibody‐positive patients diagnosed nationwide during the same period, age at diagnosis was analysed according to gender and calendar year.

Results

In Antwerp, the incidence of type 1 diabetes under age 15 increased significantly with time from 10.9/100 000/year in 1989–1993 to 15.8/100 000/year in 1999–2003 (p = 0.008). The rising incidence in children was largely restricted to boys under age 10 where the incidence more than doubled during the 15‐year period (6.8/100 000/year in 1989–1993 vs 17.2/100 000/year in 1999–2003; p < 0.001). Such an increase was not found in girls under age 10 (p = 0.54). This selective trend toward younger age at diagnosis in boys was confirmed in the larger group of Belgian patients where the median age at diagnosis decreased in boys—but not in girls—from 20 years in 1989–1993 to 15 years in 1999–2003 (p < 0.001).

Conclusions

Over a 15‐year observation period, a selective anticipation of clinical onset of type 1 diabetes was found in boys but not in girls. This suggests that an environmental factor may preferentially accelerate the sub‐clinical disease process in young boys. Copyright © 2007 John Wiley & Sons, Ltd.
Parasitic reactances and invariant properties in nonlinear networks
Authors: Suzuki Yoshihiko , Maekawa Hidehiro
Published: July 2007

The effect of parasitic reactances on the original networks as a stage in the qualitative analysis of nonlinear networks is considered. The parasitic reactances considered here are in the form of capacitors connected in parallel with resistors in the branches of a tree and inductors connected in series with the resistors in the branches of a cotree. The first result seen is the effect of the parasitic reactances on the stability of the equilibrium point. It is shown that if the equilibrium point of the original network is strongly stable and matrix (M + Mt) is positive definite, the equilibrium point is asymptotically stable even with parasitic reactances. The second result shows the effect of the parasitic reactances on the eigenvalues of the linearized equation in the vicinity of the equilibrium point. The result shows that the eigenvalues can be classified into those which converge to the eigenvalues of the original network and those which diverge to infinity of the eigenvalues of the matrix ‐M, (λ = lim [a → ∞ sgn {λ(‐M]}), when the parasitic reactances approach zero uniformly (a → ∞).
Periodically sampled queues with multiserver and finite waiting room
Authors: Yoshida Makoto
Published: July 2007

This paper evaluates the effect of periodic data transfer from an input processor to internal processors in a distributed‐control, real‐time system. Two models comprising N (≧ 1) call processors (CP) and M (≧ 0) common buffers (CPB) are analyzed and compared. In one model data transfer from the input processor is accepted at any sampling point by the CP subsystem. In the other model data transfer is not allowed if one or more calls are being processed in the CP subsystem at the time of sampling. Steady‐state distributions of calls in the system immediately after the sampling points and maximum traffic to be carried (a0) for the above two models are derived under such conditions as constant sampling period (T), Poisson arrival and negative exponential processing time distribution (mean value h). Furthermore, using such distribution, the distributions of calls in the system at any arbitrary instant are obtained to formulate various performance measures such as the average number of waiting calls in and out of the system and the average waiting time (w). Finally, the following results are shown from some examples of numerical calculation. When T/h is small, although the system with call rejection gives lower performance in terms of a0 and w, it exhibits remarkable behavior in reducing the frequency of data transfer. As T/h which is determined by the sampling period.
Design of quadrature modulator for digital FM signaling with digital signal processing
Authors: Suzuki Hiroshi , Yamao Yasushi
Published: July 2007

To introduce digital transmission into mobile communications, various digital FM methods with a modulation index of 0.5, such as TFM and GMSK, have been studied. Stable operation of these transmission systems requires high accuracy in setting the modulation index and carrier frequency in the modulator. This paper describes a quadrature modulator that provides accurate phase control using digital signal processing (DSP). GMSK is used as a modulation scheme, and its characteristics are discussed in detail. In general, the output of a modulator adapting DSP contains deviations from the ideal analog waveforms attributable to sampling, quantization and truncation errors. These errors are superposed as noise on the modulating waves and cause degradation in signal transmission. The relation between the noise spectra and the circuit parameters is first analyzed and the design procedure is then made clear in a form of a flowchart. An example of circuit parameters yielding a ratio of the signal‐to‐noise spectra of 60 dB is given. We fabricated a DPS orthogonal modulator using these parameters and confirmed that the desired modulation characteristics could be obtained.
Error rate performance of a 4‐phase DPSK system with multiple co‐channel interferences in land mobile radios
Authors: Rang Wu Ke , Morinaga Norihiko , Namekawa Toshihiko
Published: July 2007

In land mobile communications in a small zone, the same frequency is used repeatedly for efficient use of the frequency spectrum. Therefore, co‐channel interference is easily generated. An analysis is made of the statistical characteristics and error rate performance of a fading 4‐phase DPSK system when multiple channel interference with an arbitrary modulation phase number is present. It is assumed that several services in addition to voice communication will be added in the future. The probability density of two orthogonal outputs from the differential detectors is derived using the characteristic functions, and, based on this quantity, the effects of multiple co‐channel interference on the error rate are studied analytically. The resulting theoretical equation contains not only the autocorrelation of the desired wave but also the correlation of each interference wave. This makes it possible to evaluate the multiple co‐channel interference, the power distributions of each interference and the number of channels. It is assumed that the fading spectra of the desired and interference waves are symmetric with respect to the center frequency.
On decoding methods for double‐encoding systems
Authors: Imai Hideki , Nagasaka Yasuji
Published: July 2007

Double encoding is a method by which a new code is constructed by twofold encoding with two codes. Using this method, a code with excellent error‐correcting capabilities can be constructed from relatively simple codes. The decoding can also be made simpler compared with a single code with the same code length and the same error‐correcting performance. Both random and burst errors can be corrected. This paper describes a general, practical decoding method for use in a double‐encoding system. Algebraic decoding is used in both the first and the second stages, but the detailed information obtained in the first decoding is fully utilized in the second stage: the usual error‐correcting method is applied in the first decoding and a Chase algorithm is applied in the second decoding. A decoding system which is a practical simplification of the above method is also proposed. The proposed methods are compared with widely‐used conventional systems in terms of the decoding error rate; it is shown that the decoding error rate can drastically be improved.
Dielectric and conductor losses in coplanar waveguides
Authors: Koshiji Kohji , Shu Eimei , Miki Shichiro
Published: July 2007

Conductor and dielectric losses in a coplanar waveguide are analyzed and the results are verified experimentally. Since the waveguide is made of two conductors, TEM transmission is assumed and the Laplace equation for the potential distribution in the waveguide cross section is solved. From the resultant potential distributions, the current distributions on the conductor surfaces and the conductor loss are obtained. We also obtain the effective dielectric constant, which expresses the electrical effect exerted on the waveguide by the dielectric substrate. From this quantity, the dielectric loss is derived. The Laplace equation is solved numerically on a computer using the successive overrelaxation method. Only one quarter of the cross section is analyzed due to symmetry, so that computation time and memory requirements are reduced. The experiment verification of these results involves measurement of Q of a resonator consisting of a coplanar waveguide. The difference between the theoretical and experimental values is less than 25% for the conductor loss and less than 6% for the dielectric loss.
A control method of variable resonance type adaptive equalizer for a digital radio system
Authors: Matsue Hideaki , Yoshida Teruaki , Morita Kozo
Published: July 2007

In a microwave‐band highly efficient digital radio system, transmission characteristics deteriorate remarkably due to multipath fading generated on propagation paths. This paper describes a control method of adaptive equalizer using a variable resonance‐type equalizer circuit which has been developed for the correction of multipath fading. Since a received power spectrum is used for the detection of fading characteristics, the bandwidth and response speed of the detector are optimized first and, then, its control algorithm is investigated. A microcomputer is introduced for the first time in the control circuit, enabling advanced control. As a result, a well‐convergent algorithm, taking advantage of equalizing circuit characteristics, is developed.

Laboratory experiments, in a 200 Mbit/s 16 QAM (transmission speed, 50 Mband) digital radio system, using a two‐ray fading simulator confirmed that the control method has good convergency and the adaptive equalizer has sufficient equalization effects.
Insertion loss and TTE of SAW filter using 3‐transducer configuration
Authors: Setsune Kentaro , Wasa Kiyotaka
Published: July 2007

The use of a 3‐transducer SAW element configuration gives complete suppression of the triple‐transit effect (TTE) at the frequency at which the external circuit is electrically matched to the central transducer. But when designing such an element as a filter it is necessary to deal with TTE at all frequencies within the filter band. This paper discusses the TTE within the filter band for an element with a 3‐transducer configuration, assuming negligible SAW reflection. The significance of the impedances of the external circuit and the interdigital transducer, the electromechanical coupling coefficient of the substrate and the relation between bandwidth and insertion loss in obtaining 40 dB or better TTE suppression in the main signal is demonstrated. In particular, a TV‐VIF filter with the regular 3‐transducer configuration prepared on a thin‐film ZnO substrate gave 40 dB of TTE suppression in the filter band and had 11 dB insertion loss. A device with a proportional band for use in a TV‐VIF filter was prepared in order to test the theoretical calculation. The TTE and main response signals were separated by means of a pulse modulation set‐up. The TTE frequency response within the filter band was observed directly, and the 3‐transducer configuration was found to be capable of producing the low‐loss filters needed for band design without alteration of commonly‐used design methods, and is an effective method of achieving TTE suppression.
The Runge‐Kutta method with Arcs of equal length and its applications
Authors: Fukuda Kaoru , Nagashima Hideyo
Published: July 2007

The Runge‐Kutta method, a popular numerical procedure for solving a differential equation, is based on Taylor series expansions of the solution. It provides the solution if the function is single‐valued. However, it is difficult to obtain the solution in the case of a multivalued function. In this paper, a coordinate system that follows the shape of the solution is introduced for developing a numerical solution of a differential equation with a multivalued functional solution. For a step describing accurately the shape of the function, the arc length of the solution function is used. the Runge‐Kutta method with arcs of equal length is proposed in which the arc length is kept identical. From the error formula for the Runge‐Kutta method, the condition is shown under which the solution by the proposed method is more accurate than the one by the conventional Runge‐Kutta method. Next, a numerical method for a differential equation with a multivalued solution function is given by combining the new Runge‐Kutta method and the coordinate transformation. This transformation is applied not only to numerical values but also to the differential equation itself. This process can eliminate the points at which the function on the right‐hand side of the differential equation becomes singular and provide solutions even when the solution function is multivalued.
Selection of state variables for locally solvable nonlinear networks
Authors: Suzuki Yoshihiko
Published: July 2007

This paper considers the necessary and sufficient condition for the state variables for locally solvable nonlinear networks to be capacitor currents vector iC and inductor voltages vL, (iCT, vLT), instead of capacitor charges vector q and inductor fluxes vector ψ (qT, ψT). the condition is given by the regularity of matrix K and |ta, vj|→∞ as |e, j|→∞ in the resistance network where all the capacitors and inductors are replaced by voltage sources e and current sources j, respectively. Here, ie and vj are the voltage source current and current source voltage, respectively.

As a result, in the networks where (qt, ψt) can be transformed into (iCT, vLT), the network dynamics can be described in the same way as in a linear system and global consideration on networks can be done only by investigating the property of matrix KA. For example, the sufficient condition for the equilibrium point to be globally asymptotic‐stable is given comparatively easily, the consideration on eventual passivity can be done easily, and, in general, there exist various analysis methods such as in the case where (qT, ψT) are used as state variables.
Analysis of the M/G/1 and GI/M/1 queueing systems by the supplementary variable approach
Authors: Nogami Shinya , Komota Yasuo , Hoshiko Yukio
Published: July 2007

Studies on the analysis of M/G/1 and GI/M/1 using the supplementary variable approach have already been reported. However, there has been no study which analyzed consistently the systems from the transient state to the steady state.

Using the remaining service time of a customer being served in the M/G/1 and the residual interarrival time in the GI/M/1 as supplementary variables, we derive the basic equations of state probability density functions and state transition probability density functions which describe the behavior of the systems and the transient distributions of characteristic quantities, such as queue length, virtual waiting time, etc. the transient solution is derived as a solution of certain initial‐value‐ and boundary‐value problems. Using this solution, the transient solutions of the characteristic quantities (including queue length, virtual waiting time, mean queue length, mean virtual waiting time, etc.) are derived. Furthermore, by applying the final value theorem of Laplace transform to these results, we obtain stationary distributions of the characteristic quantities which equal those results obtained by imbedded Markov chain analysis.
A wiring problem on single‐layer printed circuit board without mounting modules upside‐down
Authors: Masuda Sumio , Kashiwabara Toshinobu , Fujisawa Toshio
Published: July 2007

In some cases of realizing a circuit on a single‐layer printed board, all modules are mounted on the same side of the board. This paper proposes an algorithm, assuming that a circuit contains modules which cannot be mounted upside‐down, to determine whether or not a single‐layer printed wiring is possible under the following two restrictions: (i) the modules can be mounted only on the specified side of the board; (ii) wiring should not be made under the module. the notion of PQ tree is extended as the data structure in the proposed algorithm, and the computational time is proportional to the total number of terminals in the circuit.
A surface current detector for high‐frequency currents on a metal surface
Authors: Nagasawa Yoji , Sato Risaburo
Published: July 2007

It is very important from the viewpoint of environmental electromagnetic engineering to detect vectors of high‐frequency currents on a metal plate (high‐frequency surface currents). In this paper, a high‐frequency surface current detector has been realized based on the coupling theory between an electromagnetic plane wave and a wire above the earth, and by modelling this arrangement. For the modelling, it has been considered that the electric field is approximately perpendicular to the metal plane in the space near its surface due to the surface currents flowing along the plate; and that the magnetic field is parallel to the metal plane. In practice, the pointing vector carried by the magnetic field is measured. It has been confirmed that the detector actually made can detect the vectors of surface currents by detecting progressing waves generated along a metal plane. the coupling coefficient between the surface currents and detector has been obtained experimentally by varying the parameters of the coupling line.
Formation of an evaporated thin‐film CdSe rectifying barrier by controlling the deposition rate
Authors: Yuasa Yasuhito , Ema Yoshinori , Hayashi Toshiya
Published: July 2007

The formation of a rectifying barrier using the variation with deposition rate of the resistivity of the evaporated thin CdSe film is described. Characteristics of the devices are measured and compared with the theoretical values.

Substrate temperature is maintained at room temperature during the deposition. For a deposition rate of 11.5 Å sec−1, the film has an excess of Cd and therefore exhibits n+‐type characteristics with a resistivity of 0.05 Ωcm. On the other hand, for a deposition rate of 20.0 Å sec−1 the film exhibits n‐type characteristics with a resistivity of 0.25 Ω cm. the structure of the device is as follows: an Au film is first deposited on a glass substrate, and a CdSe film, 3200 Å in thickness, is then formed at a high deposition rate (n‐type) and, subsequently, CdSe of 4450 Å thickness is formed at a low deposition rate (n+‐type). Finally, an Au film is deposited on top of the CdSe film in the final stage of formation of the device. the forward‐bias voltage of the device rises at 0.25 V and the reverse‐bias voltage is 3.5 V. Further, the index number of the forward‐rectifying characteristics is calculated to be 1.99, indicative of a good device. Moreover, the capacitance and temperature dependence of the I‐V characteristics are measured and are used to explain the properties of the device, using diffusion theory. As a result, the barrier height from the metal side is 0.54 V, the diffusion voltage is 0.48 V and the depletion layer (at OV) is 895 Å.
Optronic controllable functions of S‐type negative resistance circuits using photocoupled FETs
Authors: Takahashi Haruo
Published: July 2007

The photocoupler has been widely used as an interface element for circuit coupling functions. A light‐emitting diode is used on one side and the second side consists of an FET‐optocoupler. This combination of elements can be used as an optronit controllable device which exhibits optically controlled negative resistance characteristics.

A negative resistance circuit consisting of a combination of two photocouplers is discussed and a reversible switch in this circuit capable of flip‐flop switching is experimentally demonstrated. A negative resistance circuit with bilateral characteristics that are independent of the polarity of the applied voltage is also proposed. This circuit can control the polarity selection of the negative resistance characteristics, depending on the external light. Phase control of the starting AC voltage, as well as oscillation control of a bilateral relaxation oscillator circuit are discussed on the basis of the experimental results.
Fundamental theory on regeneration of high‐quality image
Authors: Iijima Taizo
Published: July 2007

In many cases of image description, it is often required to maintain high distinctivity to deal with the dissolving ability of the human eye. However, since ordinary images contain high redundancy, in the processes such as storage, transmission and processing with which a human operator is not concerned directly, it is desirable to compress the image information into the least but necessary size to achieve efficiency. In this paper, we attempt to establish a rational theory when a high‐quality image containing redundancy is reconstructed from compressed image information. We have obtained a reconstruction theory for a high‐quality image as well as a concrete formula to reconstruct an image by an interpolating polynomial. Thus, it seems to be useful to apply the results of this paper to establish an image processing technique to make many practical images, such as TV images, facsimile images, CT images, of high quality.
Reliability of arc‐fusion spliced fiber with a reinforcing element
Authors: Matsumoto Michito , Haibara Tadashi , Miyauchi Mitsuru
Published: July 2007

Due to the fact that optical fiber cable technology is entering the stage where it can be of practical use, the need to improve the reliability of the arc‐fusion spliced parts of fibers has become important. Although the improvement in the strength of the spliced parts of fibers has been studied and various methods of reinforcing them have been developed, to date, the breakdown mechanism of the fibers within their reinforcing elements has not been analyzed sufficiently. In this paper, the “pushing out” of a fiber from its “coat” and the transmission of torsion of a fiber within a reinforcing element have been examined. These have not been considered before as types of stress acting on an arc‐fusion spliced part of a fiber. It has been found that fiber breakdown is caused by the combined effect of a buckling stress due to fiber pushing out and a torsion stress. It has been found also that reinforcing the spliced parts of a fiber with a heat‐shrink tube is a highly reliable method having excellent characteristics for preventing the pushing out and torsion of the fiber. A spliced part of the fiber, which has been reinforced with a heat‐shrink tube, also has an excellent light transmission characteristic. For example, transmission loss at the spliced part is only 0.02 dB at −70°C.
Phase matched optical dielectric waveguide using the artificial anisotropic structure
Authors: Mizumoto Tetsuya , Naito Yoshiyuki
Published: July 2007

Birefringent material in a thin film dielectric waveguide is used to realize phase matching of the waves with different polarizations. However, this method cannot be used exclusively due to lattice mismatch as happens in a mode conversion type isolator. This paper proposes an artificial anisotropic waveguide realizing phase matching with isotropic dielectric materials only. the structure is a slab waveguide loaded with dielectric strips parallel to the wave propagation direction. This structure can equalize the phase velocities of the Ex and Ey modes. A numerical analysis based on the mode matching technique is used to obtain the phase match condition. the effect of an artificial anisotropy is confirmed in a waveguide fabricated in experiments. A waveguide is realized in which difference of the propagation constants of the Ex and Ey modes is extremely small. It is believed possible that a thin film optical isolator can be reproduced with this waveguide.
Applications of wave digital filters to branching filters with low coefficient sensitivity
Authors: Suzuki Masatoshi , Wakabayashi Hiroyuki , Miki Nobuhiro , Nagai Nobuo
Published: July 2007

Wave digital filters made to imitate the behavior of doubly terminated lossless filters (resistance terminated reactance circuits) are a class of digital filters with low coefficient sensitivity. A wave digital filter can realize not only an input‐output transfer function, but also an input reflection coefficient of the doubly terminated lossless filter. However, so far, almost no consideration has been given to the realization of the reflection coefficient by wave digital filters. This paper shows that wave digital filters can be applied to branching filters, narrowband eliminate filters and multibranching filters by utilizing two transfer functions of wave digital filters. Some examples show that these filters composed of wave digital filters can be realized with fewer multipliers and have low coefficient sensitivity properties.
A design method for low‐pass filter using nonuniform transmission lines
Authors: Kobayashi Kunikatsu , Nemoto Yoshiaki , Sato Risaburo
Published: July 2007

This paper presents a design method for the low‐pass filter using nonuniform transmission lines. First, two kinds of nonuniform transmission lines are considered‐parabolic and exponential lines. the strict and low‐frequency approximate solutions are determined for two kinds of nonuniform lines and the mixed lumped and distributed circuit consisting of parallel capacitors and uniform transmission lines. By equating those two kinds of solutions, an approximate expression is obtained for the nonuniform line made up of mixed lumped and distributed circuit. Then by using this approximate equivalence relation, sections of pre‐designed lumped and distributed circuits are approximately replaced by nonuniform lines. Due to the replacement by approximate elements, the resulting circuit has characteristics different from the original lumped and distributed circuit. It was seen from several numerical examples that the circuit made up of nonuniform lines has steeper roll‐off characteristics and larger attenuation in the stop‐band than the lumped and distributed circuit and are suited for a low‐pass filter. It is observed also that the circuit made up of nonuniform lines can reduce the number of lumped capacitors more than the lumped and distributed circuit.
Coated optical fiber for high strength splice
Authors: Kukita Shigezo , Kimura Takao , Nihei Fumihiro , Sakamoto Akira
Published: July 2007

Introduction of optical fibers into subscriber loops requires further improvements in the structure of coated fibers presently in use. Further improvements are required also in a splice technique which ensures simple installation and reliable system performance in various environments. the present coated‐fiber structure rquires removal of all coatings in the splice which degrades splice strength. This paper describes a new coated fiber structure which allows splicing without removal of the primary coating. This has improved the strength by a factor of two as well as splice time by a factor of three. This structure also showed optical transmission characteristics which are comparable to the conventional coated fiber.
Numerical analysis of the horizontal antenna above a lossy ground
Authors: Nakagawa Kinsaku , Inagaki Naoki
Published: July 2007

Since the electric field integral equation for the horizontal antenna above a ground contains a kernel of the form δ2/δxδz f (x, z) derived from the vertical Herz potential, its numerical integration is difficult. In this paper, it is shown that this kernel can be transformed to the form δ2/δx2 g(x, z) so that the moment method can easily be introduced without approximation of the kernel by the reflection coefficient method (RCM). Numerical calculations have been performed for the input impedance and the radiation pattern of a half‐wave antenna above a typical lossy ground at 60 MHz in terms of height, relative dielectric constant and conductivity as well as the thickness parameter ω. the resistive part of the computed input impedance agrees almost with the value by the RCM, whereas the discrepancy between two methods increases in the reactance for a fatter antenna if the antenna height is less than about 0.4 times the height. the input impedance vs. the ground conductivity varies abruptly near the transition σ = ωϵ0ϵs from capacitive to conductive nature in the ground. If the height is half wavelength, the H‐plane pattern has the main radiation direction at 62 degrees and hence long‐distance communication is possible by ionospheric reflection. In the case of the ground, about ‐9 dB of the electric field in the maximum direction remains near the zenith and the beam is different from that for perfect conductor cases.
Digital delay locked loop
Authors: Kuroda Akihiro , Nakagawa Masao
Published: July 2007

In spread spectrum communication systems, Delay Locked Loops (DLL) are used widely for synchronizing the spreaded signal, which is the most important part at the receiver side. However, the conventional DLL's are all analog ones. Considering reliability, compactness and programmability, the DLL's are well worth digitalizing. In this paper we propose a new digital DLL. This loop has concise constitution and good performances.
Analysis of strip‐line circuit by planar circuit approach—Application of higher‐mode impedance concept
Authors: Hsu Jui‐Pang , Anada Tetsuo
Published: July 2007

Triplate‐line circuit and strip‐line circuit are the circuit structures used frequently at microwave and millimetric wave frequency bands. In these frequency bands, the strip‐line width is not negligible compared with the wavelength. Also, the presence of electromagnetic field disturbance at junction and the mutual interaction of the frequency bands has strong effects on frequency characteristics. In this paper, to treat this kind of problem, the strip transmission line circuit is modeled and it is shown that the electromagnetic field distribution in this model is determined by the planar circuit equations. In solving these planar circuit equations, the circuit is separated into transmission line and junction circuit, and the mode impedance for each circuit is derived. It is shown that the input/output characteristics of the strip‐line circuit are obtained by making analogous circuit equations conventional equations and solving them. This method of analysis is applied to a simple triplateline circuit and its wideband frequency characteristic is calculated for dc 18 GHz. Furthermore, the corresponding circuit is constructed and its frequency characteristic is measured for 4 ± 18 GHz. Since the calculated results based on this method of analysis agrees well with the measured results, the validity of this method of analysis is confirmed.
A new maximum likelihood decoding of high rate convolutional codes using a trellis
Authors: Yamada Takahiro , Harashima Hiroshi , Miyakawa Hiroshi
Published: July 2007

Maximum likelihood decoding of convolutional codes by Viterbi decoding method is an effective error correcting technique. However, little study on Viterbi decoding of high rate codes has been done since the number of paths entering each trellis state increases as the code rate increases. This paper presents a new maximum likelihood decoding of convolutional codes of rate (n ‐ 1)/n using a trellis. the trellis is drawn according to the state transitions of the syndrome former of the code, and has only one or two paths entering each state rather than 2n‐1 paths as in the case of conventional trellises. Thus, we can replace the 2n‐1‐ary comparisons at each state needed in the conventional Viterbi decoding for the code of rate (n ‐ 1)/n by binary comparisons. the implementation of maximum likelihood decoders for high rate convolutional codes is simplified greatly by this approach. Moreover, this decoding method shows the same performance as that of conventional Viterbi decoding method from the viewpoint of selecting the maximum likelihood code sequence.
Characteristics of microwave power absorption in an insect exposed to standing‐wave fields
Authors: Fujiwara Osamu , Goto Yoshiyuki , Amemiya Yoshifumi
Published: July 2007

In the study of microwave biological effects, microwave irradiation experiments with pupae of insect (Tenebrio molitor) are performed actively. Experiments of this kind showed that the developmental anomalies produced by microwave irradiation on the pupae can not be explained simply by only the thermal effect. As a result, there has been considerable discussion on the nonthermal effects of microwaves. Among the many experiments, Olsen's 6‐GHz band standing‐wave irradiation experiment is noteworthy because it ignores the above nonthermal effects in that developmental anomalies depend only on the absorptive ability of the pupa. In a standing‐wave experiment performed using the 2 GHz band, the result differed from that in the 6 GHz band. Thus we observed that the heating pattern distribution within a pupa is related to developmental anomalies. Using this prospective, this paper analyzes the absorbed power in a pupa exposed to microwave standing‐wave electromagnetic fields and clarifies the characteristics of the absorbed power to the frequency as it relates to exposure locations. the results showed that a pupa can be exposed to an approximately uniform electromagnetic field separated into individual components of the fields in the 2 GHz band; however, this does not hold in the 6 Hz band. Moreover, distribution of heating potential (absorbed power per unit volume) within a pupa differs remarkably between the two frequency bands.
Considerations of SNR improvement characteristics of the optimum linear filter of systems with signal‐dependent noises
Authors: Kuwahara Ichiro , Takahara Mikio , Amemiya Masaki
Published: July 2007

This paper proposes a new expression model of signal‐dependent noises such as shot noise, multiplicative noise, etc., by introducing signal dependent index n. the optimum linear filter on the signal‐to‐noise‐ratio (SNR) criterion in transmission systems containing additive noise, some signal dependent noises, and intersymbol‐interference, is derived. the optimum filter can be regarded as an extended matched filter from the used criterion. By assuming Gaussian input signal waveforms, SNR improvements by the optimum filter are obtained through numerical calculation. We have shown that the SNR improvement increases as the signal‐dependent index n of the dominant noise of the system increases, the improvement of intersymbol‐interference is large, and the optimum filter operates so as to eliminate first the dominant noise of the system. Moreover, it is shown that SNR of the optimum filter varies according to the value of the standard deviation of a signal waveform and has a certain maximum value when the standard deviation varies under the constant signal energy. the SNR improvement characteristics by this filter are compared to those of the full cosine roll‐off filter and the advantage of this filter is shown quantitatively.
Influences of circuit design on the characteristics of soft error in MOS dynamic RAMs
Authors: Yoshihara Tsutomu , Mashiko Koichiro , Takano Satoshi , Nakano Takao , Nagayama Yasuji
Published: July 2007

The circuit design of MOS dynamic RAM has a great influence on its fsoft errors; effects of capacity of the dummy cell, the word line potential, sensitivity of the sense amplifier, and their mutual timing, on soft errors were observed in accelerated tests with radioisotopes. the ratio of the dummy cell capacity to the memory cell capacity determines critical charges for “1” and “0,” the smaller of which controls the soft error rate. the soft error rate was reduced to one‐tenth by rainsing the word line potential before operation of the sense amplifier is improved by preserving sufficient time for grounding of its flip‐flop terminal and that the soft error rate is proportional to the bit line floating time. the error is minimized by adjusting properly the operation time of the sense amplifier.
Coherent characteristics of superconducting closed loop composed of Josephson junctions
Authors: Kobayashi Tadayuki , Kondo Nobuyoshi , Hamasaki Katsuyoshi , Yamashita Tsutomu
Published: July 2007

When the impedance of a Josephson junction is too low, the elements are connected in series. We connected two arrays with N series elements of Josephson junctions each (denoted 2N‐JJ loop) and tried to find conditions for it to operate coherently by investigating voltage‐current curves. the computer simulation showed that coherent operation is easier with this circuit than with a series connection of the elements when the elements have different junction parameters. Pb‐alloy tunnel‐type junctions were produced which have N = 2 and 3, and we found that voltage steps generated by application of rf current with frequency F have a voltige interval corresponding to NF. This agrees with the simulation results and indicates coherent operation.
A 256 bit 12L RAM with a high‐voltage analog circuit
Authors: Kaneko Kenji , Okabe Takahiro , Maio Kenji , Nagata Minoru , Matsumoto Keizo
Published: July 2007

Recently, it has become desirable for the analog‐digital LSI to have ROM, PLA, or RAM in addition to the conventional random logic circuits: I2L described in this paper is suitable for these purposes with its capability to be on‐chip with high‐voltage analog circuits. to suppress the circuit area increase which is the largest problem in coexistence with the high‐voltage devices, this RAM has a simplified peripheral circuit by an extensive use of I2L devices. Also, it has a circuit configuration which minimizes the number of device isolation regions. As operating features, it uses the memory cell read‐out transistor in the reverse mode during the signal read‐out in association with the simplification of the circuit configuration. Thus, it is possible to set up the power consumption according to its use. As a result of the fabrication of 256 bit RAM using the process technology for high‐voltage analog circuits (epitaxial layer: 1 ω cm, 10 μm, device‐isolation distance: 20 μm), npn transistor breakdown voltage BVCEO of 22 V, RAM area of 1.7 × 3.4 mm2, minimum access time 600 ns, and minimum write pulsewidth of 440 ns have been obtained.
Optimal design for two dimensional recursive digital filters
Authors: Fukuzawa Junji , Shimizu Kiyotaka
Published: July 2007

Techniques are proposed for the design of two‐dimensional recursive filters approximating simultaneously prescribed specifications of magnitude and group delay. By treating the coefficients of the transfer function as decision variables, these approximation problems are formulated as (1) preference optimization problem and (2) optimization‐satisfaction problem, in order to obtain optimal transfer functions. In Case (1) an optimal preference solution is selected by a designer interactively from among a set of non‐inferior solutions of a 2‐object optimization problem for two performance indices of magnitude and group delay. In Case (2) the performance index for magnitude is optimized under the satisfaction condition so that the index of approximation error of group delay is always within a specified value. Finally, design examples from these two techniques are given.
Monolithic crystal filters exhibiting improved symmetric passband characteristics by means of two‐dimensional electrode arrangement
Authors: Sekimoto Hitoshi
Published: July 2007

Many one‐dimensional arrangements have been used with only unilateral elastic coupling for electrode arrangement of a monolithic crystal filter (MCF). However, such an arrangement has the disadvantage that disturbance occurs within the passband and asymmetry of the characteristic increases with the specific bandwidth of the filter. to remedy this, the present paper proposes an MCF with two‐dimensional electrode arrangement to allow the bridged coupling to be zero. First, confirming that the bridged coupling between nonadjacent electrodes is a main factor disturbing the passband characteristic, a method of achieving zero bridged coupling between electrodes is provided by means of two‐dimensionally arranged electrodes. A design procedure for an MCF with two‐dimensionally arranged electrodes MCF is then introduced based on the M‐coupled equivalent circuit. Furthermore, a tandem arrangement with electrodes of different length is shown to be valid for suppression of skew symmetric modes necessarily excited in the two‐dimensional arrangement. Lastly, design of a 9‐resonator, tandem crystal MCF with 0.5% specific bandwidth is presented to decrease disturbance of the in‐band ripple and asymmetry of the passband and rising characteristics. Moreover, undesired response caused by the skew symmetric mode is seen to be suppressed sufficiently without difficulty in practical use.
Numerical analysis of plane wave scattering from a cylindrical scatterer with edge points by the mode matching method—the h‐wave case
Authors: Okuno Yoichi , Matsuda Toyonori , Yasuura Kamenosuke
Published: July 2007

A mode matching algorithm with a second‐order smoothing process is proposed for accurate and efficient analysis of H‐wave scattering from a cylindrical body with edge points in the resonant region. the smoothing process is a method for transforming the boundary condition for the wave function to a smoother one by way of an indefinite integral. Since the smoothed condition can more easily be satisfied than the original boundary condition, convergence of the approximate wave function series by modal expansion can be accelerated by the smoothing process. In H‐type scattering problems, the first‐order indefinite integral can be evaluated by the conventional smoothing process without considering the existence of edge points. However, since convergence of the mode matching solution with the smoothing process is not fast enough, accurate solutions are difficult to obtain. Hence, second‐order smoothing is used in this paper. In this case, even for H‐type problems, the algorithm has to rely on the singular smoothing technique considering the edge point. Therefore, the algorithm becomes a mode matching technique in which the conventional smoothing and singular smoothing are combined. to find the effectiveness of the method, the problem of plane wave scattering by a conducting rectangular cylinder is numerically calculated. It is found that significant improvement is achieved in accuracy of the solution.
Burst‐error‐correction capability of cyclic codes
Authors: Tokiwa Kinichiroh , Kasahara Masan , Namekawa Toshihiko
Published: July 2007

Previously, the algebraic error‐correcting codes have usually been investigated independently for each error type [random, burst or compound]. the demand for high‐performance error‐correcting codes, however, has increased considerably due to the remarkable progress on many fields of digital communication. to meet this demand, a new research direction has been adopted by Matt‐Massey, Wang and the authors, reevaluating the burst‐error‐correction capability of the cyclic codes.

In this paper an algorithm based on the generator matrix is proposed to analyze the burst‐error‐correction capability of cyclic codes. This algorithm appears particularly efficient in terms of the amount of computation. to apply the method in practice, a number of burst‐error‐correction cyclic codes has been investigated, and this paper presents some of the results obtained. Finally, a very interesting conjecture is given, which relates to the burst‐error‐correction capability of the maximum‐strength sequence codes.
A fast calculation algorithm for a parameter estimation of autoregressive and moving‐average model
Authors: Miyanaga Yoshikazu , Watanabe Hiroshi , Miki Nobuhiro , Nagai Nobuo
Published: July 2007

Levinson's algorithm is one of the fast algorithms for estimating the parameters of an auto‐regressive model. Since this algorithm is recursive with respect to the order of a model, it is an effective method to obtain models of various orders when the true order is unknown. This paper proposes a fast algorithm to estimate the parameters of an autoregressive and a movingaverage model. the parameter estimation can be accomplished using a criterion based on the least square method. the problem of estimating autoregressive and moving‐average parameters from the criterion is reduced to that of solving a 2 × 2 block Toeplitz matrix. This method is an algorithm to solve this block Toeplitz matrix rapidly and it does not require the calculation of the inverse matrix. Also, it is recursive with respect to the order; the orders of an autoregressive model and a moving‐average model can be changed independently of each other. This method is an expansion of Levinson's algorithm and this paper shows the relationship between this method and Levinson's algorithm. Furthermore, properties of this method are discussed and as an example of its application, an experiment of model reduction is performed.
Frequency keeping algorithm for atomic reference frequency and clock supply
Authors: Kihara Masami , Jumonji Hiromichi
Published: July 2007

A high‐accuracy cesium atomic oscillator is used as a clock for a digital communication network, in which, for instance, three cesium oscillators are used to take statistical average with the aid of a reference clock. We will discuss the algorithm for monitoring the frequency error by assuming a step frequency deviation. It has been confirmed that the algorithm satisfies the CCITT Time Interval Error requirements and that it switches to a normal cesium oscillator when frequency error is detected.
Separating capacity of a cascaded network of threshold elements
Authors: Takiyama Ryuzo
Published: July 2007

This paper discusses the information processing ability of the cascade network of threshold elements, which is a fundamental structure to realize a piecewise‐linear machine. the upper bounds for the number of dichotomies and the separating capacity are determined for that type of network, where theory of equivalent transformation from cascade network to two‐layered network is utilized positively. As a result, it is shown that the upper bound for the separating capacity of the cascade network consisting of k threshold elements is given by 2k(n + 1), where n is the dimension of the patterns to be classified.
Constitution of satellite switched TDMA network
Authors: Akiyama Minoru , Hirose Masatoshi
Published: July 2007

In constituting a satellite switched TDMA network with a multispot beam satellite it is necessary to determine an on‐board switching scheme and access scheme from an earth station, taking account of traffic intensity and number of stations in a beam, and to design an efficient system. This paper discusses the optimal design method, assuming that the satellite has both a microwave switch and a baseband switch. First, a traffic analysis method is shown for each switching scheme and access scheme, and the applicability of each scheme is investigated using the cost of an on‐board switch, etc., as criteria. Next, it is revealed to be about 20% effective in switch cost to use baseband switch channels as the final circuit to absorb overflow traffic from microwave switch channels.