An efficient full–wave spectral domain moment method is developed to compute the current distribution and the radiation associated with microstrip discontinuities. Two techniques are used to increase the efficiency of the method of moments algorithm so that a transmission line of moderate electrical size can be analyzed in reasonable time.

In this paper, we subjects the case that frequency–shift–keying (FSK) modulation and phase locked loop (PLL) demodulator are used in frequency hopped spread spectrum (FH–SS) communication system. So the carrier frequencies of undesired transmitters may come into collision with the carrier frequency of desired transmitter in this communication system, we evaluate the response of PLL by two sinusoidal inputs so as to estimate how the response of PLL demodulator is affected by the collision of carrier frequencies. First, we compute the synchronization diagrams of PLL with two sinusoids. From this, it is indicated that allowable value of amplitude ratio of interference transmitter's signal to disired transmitter's signal decreases with increasing FSK modulation width of desired transmitter. Next, we calculated the output of PLL demodulator with two sinusoids. To this end, it is shown that the allowable value of amplitude ratio is bounded by a constant value even if FSK modulation width is enough small.

A three-dimensional analysis of Whispering-Gallery modes (W. G. modes) in a coaxial dielectric resonator is proposed and presented. The coaxial dielectric resonator is constructed from a lossy dielectric disk and ring which have diameters of several tens times as large as wavelength. Eigenvalue equations of the W. G. modes are derived rigorously from field expressions and boundary conditions. The resonant frequencies, unloaded Q values and field distributions are calculated numerically from the eigenvalue equations. These calculated results are in good agreement with experimental ones for an X band model. As a result, it is shown that a considerable quantity of modal energy can be confined in a loss-less gap between the disk and ring, and then the unloaded Q value is higher than that of a conventional dielectric disk and ring resonator.

The authors have studied mechanism of transition from metallic phase to gaseous phase in contact break arc. For further elucidation of the mechanism, we have carried out spectroscopic measurement. The spectrum measurement system which had high time resolution was composed using two monochromators and a bifurcated image fiber, which had one input port and two output ports. The input port received the arc light, and the two monochromators received the arc light from the two output ports, respectively. The spectral sensitivity of the two monochromators was corrected with a standard lamp. We have measured simultaneously two spectra of break arc for Ag in laboratory air, under the condition where source voltage E=48 V, load inductance L=2.3 mH, and closed contact current I0=6 A. As a result, the time-varying tendency of spectrum intensity is similar for the same element, even if the wavelength is different. And from the comparison of time average spectrum intensity, it is clarified that average intensity for gas spectrum does not attain to 10% of that for metallic atomic spectrum (Ag I, 520.91 nm). In addition, the decrease point of Ag II (ion) spectrum has been found to correspond with the peak of Ag I (atom) spectrum.

As a result of examination based on a newly available data set of millimeter-wave rain attenuation measured in the UK, it is found that the ITU-R specific rain attenuation model tends to appreciably underestimate millimeter-wave rain attenuation at frequencies above about 60GHz for the UK rain climate. This tendency is very similar to that previously reported for the Japanese experimental data at frequencies up to 245GHz. Furthermore, an alternative specific rain attenuation model based on the Japanese experimental data is found to be in fairly good agreement with the experimental data in the UK at frequencies up to 137GHz.

This paper describes a simple system of measuring the spatial distributions of spectral intensities with AgI-421 nm and AgI-546 nm among many optical spectrums emitted from an arc discharge between separating Ag contacts. In order to detect the intensities of two optical spectrums, the prototype equipment has two sets assembled with a CCD color linear image sensor, a lens and optical filters, which are arranged on rectangularity. The intensities of two spectrums can be recorded with 2 ms time-resolution within a long arc duration on a digital memory. The recorded digital signals are processed by using a personal computer in order to reconstruct two spatial distributions of spectral intensities in a cross section of arc column with the Algebraic Reconstruction Technique.

Parallel processing in speech recognition is described, which is carried out at each frame on time axis. We have already proposed a parallel processing algorithm for HMM (Hidden Markov Model)-based speech recognition using Markov Random Fields (MRF). The parallel processing is realized by modeling the hidden state sequence by an MRF and using the Iterated Conditional Modes (ICM) algorithm to estimate the optimal state sequence given an observation sequence and model parameters. However this parallel processing with the ICM algorithm is applicable only to the standard HMM but not to the improved HMM like the linear predictive HMM which takes into account the correlations between nearby observation vectors. In this paper we propose a parallel processing algorithm applicable to the correlation-considered HMM, where a new deterministic relaxation algorithm called the Generalized ICM (GICM) algorithm is used instead of the ICM algorithm for estimation of the optimal state sequence. Speaker independent isolated word recognition experiments show the effectiveness of the proposed parallel processing using the GICM algorithm.

We have studied in detail the effect of gas flow rates on the film properties of low-temperature (300) polycrystalline silicon (poly-Si) films prepared by conventional plasma enhanced chemical vapor deposition (13.56 MHz) with SiF4/SiH4/H2 gases. The effect of SiH4 flow rate on crystallization is shown to be large. A small amount of SiH4 with high SiF4 and H2 flow rates (50[H2]/[SiH4]1200, 20[SiF4]/[SiH4]150, 1[H2]/[SiF4]16) is important to form poly-Si films. The poly-Si films deposited under such optimized conditions had shown preferential 〈110〉-orientation and the crystalline fraction is estimated to be more than 80%. The deposition rates are in the range of 5-30 nm/min. The conductivity is in the range of 10-8-10-6 S/cm. Further, the electrical conduction indicates an activation type, and the activation energy is in the range of 0.5-0.6 eV.

A new method for the accurate extraction of glottal source parameters is proposed. This method, called Heuristic Analysis-by-Synthesis (HAbS), has been developed specifically to overcome the weaknesses of other methods of glottal source parameter extraction. The specific features of this method are the use of the AbS method for extraction of glottal source and vocal tract parameters, the use of a parametric glottal source model during vocal tract analysis, the use of alternating glottal source and vocal tract analyses, and simultaneous, time-domain analysis of the glottal source parameters and the first formant. This method has been implemented in such a way that user interaction is not required. The performance of the HAbS method is evaluated using both synthetic-speech and natural-speech data. Error is measured in both the time domain and the spectral domain, and the standard deviation of extracted parameter values is computed. In addition, the error in analysis of each glottal-source parameter is computed using synthetic-speech data. In order to assess the accuracy of the HAbS method as compared to other methods, three other methods (LPC, AIF, and AbS) are evaluated using the same data methods of error measurement. From these evaluations, it is clear that the HAbS method yields results that are more accurate than these other methods.

This paper presents a support method for specifying communication systems. Generally, a set of requirements for a target system is partial and ambiguous to construct the whole system, namely it lacks certain necessary descriptions for the target system. To attack this problem, our method enables a designer to obtain such necessary descriptions from specifications stored in a knowledge base, namely by reusing specifications, and helps the designer to specify the target system completely. In our support method, we adopt labelled transition systems (LTSs) which are state transition graphs and are shared as a common notion by most FDTs. Therefore, our method is the common approach to FDTs. We propose a new idea about similarity berween LTSs, and propose an algorithm to suggest similar LTSs to the designer.

Contextual classification of multispectral image data in remote sensing is discussed and concretely two improved contextual classifiers are proposed. The first is the extended adaptive classifier which partitions an image successively into homogeneously distributed square regions and applies a collective classification decision to each region. The second is the accelerated probabilistic relaxation which updates a classification result fast by adopting a pixelwise stopping rule. The evaluation experiment with a pseudo LANDSAT multispectral image shows that the proposed methods give higher classification accuracies than the compound decision method known as a standard contextual classifier.

This paper presents the M-LCELP (Multi-mode Learned Code Excited LPC) speech coder, which has been developed for the next generation half-rate digital cellular telephone systems. M-LCELP develops the following techniques to achieve high-quality synthetic speech at 4kb/s with practically reasonable computation and memory requirements: (1) Multi-mode and multi-codebook coding to improve coding efficiency, (2) Pitch lag differential coding with pitch tracking to reduce lag transmission rate, (3) A two-stage joint design regular-pulse codebook with common phase structure in voiced frames, to drastically reduce computation and memory requirements, (4) An efficient vector quantization for LSP parameters, (5) An adaptive MA type comb filter to suppress excitation signal inter-harmonic noise. The MOS subjective test results demonstrate that 4.075kb/s M-LCELP synthetic speech quality is mostly equivalent to that for a North American full-rate standard VSELP coder. M-LCELP codec requires 18 MOPS computation amount. The codec has been implemented using 2 floating-point dsp chips.

A new gradient type adaptive algorithm is proposed in this paper. It is formulated based on the least squares criteria while the conventional gradient algorithms are based on the least mean square criteria. The proposed algorithm has two variable parameters and by changing them we can adjust the characteristic of the algorithm from the RLS to the LMS depending on the environment. This capability of adjustment achieves the possibility of providing better solutions. However, not only it provides better solutions than the conventional algorithms under some conditions but also it provides a very interesting theoretical view point. It provides a unified view point of the adaptive algorithms including the conventional ones, i.e., the LMS or the RLS, as limited cases and it enables us to analyze the bounds for those algorithms.

We compare interfaces of Nb/AlOx-Al/Nb and Nb/ZrOx-Zr/Nb junctions using secondary ion mass spectroscopy and cross-sectional transmission electron microscopy. We have clarified that an interface of the Nb/AlOx-Al/Nb junction is drastically different from that of the Nb/ZrOxZr/Nb junction. An adsorbed water vapor layer plays an important role in suppressing grain boundary diffusion between Nb and Al at the interface of the Nb/AlOxAl/Nb junction. In depositing Nb and Al at low power and cooling the substrate, it is important to control the formation of the adsorbed water vapor layer for fabricating Nb/AlOx-Al/Nb junctions exhibiting excellent current-voltage characteristics.

Circuit techniques for realizing fast cycle time of DRAM are described. 1) A high-speed and high-efficiency word-line level Vpp supply can be obtained by a unique static CMOS double-boosted level generator (SCDB) which controls the Vpp charge supply gate. 2) A new write-control scheme eliminates the timing overhead of a read access time after write cycle in a fast page mode operation. 3) A floor plan that minimizes the load of signal paths by employing the lead-on-chip (LOC) assembly technique. These techniques are implemented in an address-multiplexed 16 Mbit CMOS DRAM using a 0.5-µm CMOS technology. A 31-ns RAS cycle time and a 19-ns fast page mode cycle time at Vcc3.3 V, and also even at Vcc1.8 V, a 53-ns RAS cycle time and a 32-ns fast page mode cycle time were achieved. This DRAM is applicable to battery-operated computing tools.

We propose a method which can construct LOTOS specifications of communication systems from temporal properties described in Extended branching time temporal logic (EBTL) in this paper. Description of LOTOS, one of Formal Description Techniques, is based on behaviors of systems so that LOTOS permits strict expression. However, it is difficult to express temporal properties explicitly. On the other hand, Temporal logic is based on properties of systems. Thus temporal logic permits direct expression of temporal properties which can be understood intuitively. Accordingly, temporal logic is more useful than FDTs on the first step of systems specification. This method is effective in this point of view. Specifications obtained using this method can have a structured style. When temporal properties are regarded as constraints about temporal order among actions of systems, those specification can have a constraint oriented style. This method is based on sequential composition of Labelled Transition Systems (LTSs) which are semantics of LOTOS. EBTL is also defined on LTSs. In general, many LTSs satisfy the same temporal property. To obtain such the minimal LTS, the standard form of LTSs corresponding to EBTL operators are defined. Those standard LTSs are mainly tailored to the field of communication protocol. We also show conditions that original temporal properties are preserved in case of sequential composition of standard LTSs. In addition, applying this method to the Abracadabra Protocol, we show that this method can construct specifications of concrete protocols effectively.

This paper reports on the properties of thin-film thermal switches that are monolithically fabricated on high-Tc superconductive filter. Operating at a wide temperature range of 50-77 K, it was found that the switch could control the center frequency by -10 MHz with an increased insertion loss of less than 0.7 dB. In an on-off switching operation of filter characteristics using thin-film switches, power consumption was approximately 20 mW at 77 K, and the signal decay time as a switching speed was 30 ms at 76 K with a switch current of 70 mA. The decay time decreased exponentially as the switch current or the temperature setting increased.

A multiple-registered architecture is described for 180 MHz 16 Mbit synchronous DRAM. The proposed architecture realizes a flexible control of critical timings such as I/O line busy time and achieves an operation at 180 MHz clock rate with area penalty of only 5.4% over the conventional DRAM.

Multilevel RLL (Runlength Limited) sequences are analyzed. Their noiseless capacity and lower bounds on the channel capacity in the presence of additive white Gaussian noise are given. Moreover, the analytical power spectra formulae for those sequences which generalize the previously derived one for binary sequences are newly derived. We conclude from the analysis of the power spectra that multilevel RLL sequences are attractive from the point of view that they increase information rate while keeping low DC-content and self-clocking capability of binary RLL sequences.

In this paper, we analyze high-Tc superconducting (HTS) microstrip antenna (MSA) using modified spectral domain moment method. Although it is assumed that the patch and the ground plane of the MSA are perfect electric conductors (PECs) in the conventional spectral domain method, we modify this method to compute the conduction loss of the HTS-MSA. In our analysis, the effect of the HTS film is introduced by the surface impedance which we can estimate by using the three fluid model and experimental results. This paper presents numerical results about the HTS-MSA, for example, the relations between the thickness of the substrate and the radiation efficiency, the temperature and the resonant frequency, and so forth. And we discuss the effective power range where the performance of the HTS-MSA is superior to that of the Cu-MSA.