Matsuo SEKINE Yoshiwo OKAMOTO TetsurNAKAMURA Ruixing LIANG
The critical temperature Tc of recent oxide superconductors in Ba-Y-Cu-O systems is considered from the complete electron-phonon interactions in two-dimensional [CuO2]-layers. It is concluded that the value of Tc does not exceed 110 K, so long as the phonon-mechanism is assumed.
Kazutoshi KOGA Hidetoshi MIIKE Masahiro MOMOTA
An exact method determining optical flow from a sequence of images is presented. We adopt a pixel-based analysis calculating mutual-correlation functions between temporal change of brightness at a targer pixel and that at neighboring ones. Local velocity at the target pixel is deceided analytically from lag times of the correlation functions.
Naohiko INABA Toshimichi SAITO Shinsaku MORI
It is known that the modified van der Poloscillator proposed by Shinriki et al. can exhibit various interesting phenomena such as a period-doubling-bifurcation, chaos, windows, and a Double Scroll like attractor. But the mechanism of the generation of such phenomena has not yet been explained and cleared. In this paper, it is shown that the phenomena generated in the Shinrikis' circuit could be well explained by a simplified model which we hereafter call as the Ideal System. Here the idealization means that the element of diodes in the circuit operates as an ideal switch. The Ideal System is extremely simple because it contains 3 reactance elements, one linear negative coductance and only one nonlinear element constructed from diodes where the operation of such nonlinear element is very simple. The advantages of using the Ideal System to analyze the mechanism of chaos are as follows: Poincaré map could be derived strictly as a 1-dimensional discrete map from this model and from this obtained Poincaré map, the phenomena could be well explained. Moreover, the theoretical results are verified in the circuit experiments. The Ideal System makes clear the mechanism of chaos gonerated in the circuit.
Masayuki TANIMOTO Takashi MORI
A hybrid scheme of subsampled DPCM and interpolative DPCM is proposed for the HDTV coding. A large bit rate reduction is realized by the two effects of pixel reduction and bit reduction. SN ratio is greatly improved compared with that of the coventional DPCM.
Yoshihiro SHIMAZU Satoki KAWANISHI Jun-ichi YAMADA Masao SUZUKI
High-speed NRZ-DMI coder and decoder monolithic ICs employing novel circuits suitable for high-speed operation have been developed using Si bipolar technology. They operate up to 1.8 Gb/s with a 3.6 GHz clock frequency. Power dissipations of the coder and decoder are 872 mW and 1333 mW, respectively.
Masaki AMEMIYA Mamoru AIKI Toshiyuki MATSUNO Yasutaka ICHIHASHI Hidetoshi SHIRAKAWA
Jitter accumulation is examined in a 122 optical regenerator line of a 4758 km submarine cable. Accumulated jitter at the 122nd regenerator is less than 3.6rms at a line bit rate 445.837 Mb/s using a 2231 pseudorandom signal. With a 2151 PN signal, obtained jitter saturates at about the 60th regenerator. These results agree with theoretical jitter accumulation estimations for PN pattern signals.
Hideaki TSUSHIMA Yoshitaka TAKASAKI Minoru MAEDA
This letter proposes an improved polarization diversity method for heterodyne/coherent optical transmission systems. It is theoretically clarified that this method can reduce the noise caused by polarization fiuctuations and can receive a binary FSK or PSK modulated signal with high sensitivity.
Butt coupling efficiency between edge-emitting LEDs operating at 1.3 and 1.55µm wavelengths and single-mode fibers, has been investigated using far-field pattern data.
Toshiaki SATAKE Shinji NAGASAWA Norio KASHIMA
Single-mode 1 N switch for 10-fiber ribbon has been developed. The switch has a movable 10-fiber connector plug and linear arrangement of 10-fiber plugs to be mated. The plugs are precisely aligned by inserting alignment pins. The tested 1 50 switch exhibits an average insertion loss of 0.5 dB for single-mode potical fibers with 10µm core. The minimum and the maximum switching times are 17 msec for port 1 to 2 and 80 msec for port 1 to 50, respectively. Insertion loss change after over 1000 times switching is less than 0.1 dB.
Yoshimasa DAIDO Sadao TAKENAKA Hiroshi NAKAMURA
Since power penalty of multilevel QAM system is caused by many simultaneously existing impairments, it is important to know whether the sum of the penalties caused by each impairment coincides with the power penalty caused by the actual channel condition or not. To examine the combined effect caused by plural impairments, theoretical power penalty is estimated in detail when any two impairments among the typical seven exist simultaneously. The excess penalty is defined as deviation of the power penalty from the sum of penalties caused by each impairment. Calculation of the excess penalty shows that there are four categories for combinations of impairments. It is shown that there is a typical category of combinations which includes more than half of all possible combinations. Calculated excess penalties are very close for all combinations within this category. A simple algebraic equation is given to approximate the excess penalty for the category. The excess penalties of other categories will be shown and their characteristics will be discussed in detail.
We are trying to automate the optimum design and production of a set of physical masks for functional IC's. Our bit-map CAD for bottom-up IC design of mask pattern, coupled to a direct-write-on-wafer electron-beam (SEM) lithography system, has been used to design a D/A conversion circuit for an innerproduct multiplier so as to reduce the chip area drastically. We also have developed a program for automatic mask pattern generation from a schematic logic description. Even with parameter extractions from a trial-fabricated IC, we have been able to design and produce optimum IC's in a very short time.
Toshiaki SAKATE Norio KASHIMA Masayuki OKI
A small plastic molded 50-fiber connector has been developed for high-count optical subscriber cables. The connetor ferrule has a two-dimensional fiber arrangement constructed by five layered 10-fiber ribbons. The ferrules are precisely aligned by alignment pins and a guide sleeve. The fabricated 50-fiber connector, which has a small sectional area of 4 mm6 mm, exhibits an average loss of 0.23 dB for graded-index optical fibers. Connection loss chang is small after over 1000 times reconnection.
Kunihito USUI Hiroyuki ARAI Naohisa GOTO
One of the key technologies in the RF heating is the design of vacuum windows. This paper presents the theory of a pill-box shaped vacuum window connected with circular waveguides. We solved it regarded as a typical boundary value problem of microwave circuits, and evaluated its reflection coefficient and field distributions inside the window.
A Gaussian pulse propagated through a multimode optical fiber is well explained by introducing a weighting function of higher order modes into the theoretical formula, being consistent with experimental results. Extending the equation of the pulse propagation in a single mode fiber into that for the multimode fiber, the calculated waveform with several weighting functions is compared with the experimental pulse of a He-Ne 3.39µm mode-locked laser, which propagated through As-S glass fiber. Cosequently, the most appropriate weighting function is found to be hyperbolic function W(l)l-0.7, which depends only on the radial mode l and is independent of the azimuthal mode m. Physical interpretation about the obtained weighting function is also discussed.
Kazunori UCHIDA Toshiaki MATSUNAGA Takeaki NODA
This paper is concerned with the theoretical and experimental study of electromagnetic wave excitation in a tunnel with a cross-junction. In the analyses, a surface impedance model is introduced for the boundary conditions on the tunnel walls to take into account their dissipative effect on propagation. Experiments based on a microwave simulation are also performed in order to check whether the surface impedance approximation is valid or not for a bended tunnel. It is found that numerical and experimental results agree well regarding electric field intensity in each tunnel.
This study describes the relationship between the recognition of shape and the electromyogram(EMG)generated on the surface of the human hand. Three spectral peaks(100, 160, and 250 Hz)were obtained after grasping each shape(sphere, tetrahedron, and cube). Peaks in the EMG spectra were identical in frequency for each shape. Feature extraction of different forms could not therefore be quantified as spectral variation in the EMG.
Hideki NAKAJIMA Takako ITOH Yakichi KANATA
The purpose of this paper is to facilitate an objective diagnosis of a disordered retina on the stand point of engineering. We have analyzed the frequency of every ERG (electroretinogram) with the MEM (maximum entropy method) algorithm to distinguish the normal ERG from the disordered ERGs.
This paper describes measured results of details of arc voltage fluctuations and a surge in breaking Ag contacts.
This paper describes the refined analysis of the angle-tracking performance of a coherent amplitude-comparison monopulse radar system in the presence of an interfering second target and, on the basis of the results, proposes a new improved system. The original system investigated by Kliger & Olenberger deteriorates the tracking performance for the wideband AGC in combination with narrowband PLL case. By appropriately combining systems with and without PLL, our new system is shown to have good tracking performance for all bandwidth" of the AGC and PLL relative to the Doppler separation.
Ivan STOJMENOVI Masahiro MIYAKAWA
We show that symmetric Boolean fanout-free functions or cascade functions realizable by networks of AND's, OR's and inverters are only the functions 0, 1, x1x2xn, x1+x2+xn,