In 1985, Kues et al. (Bioelectromagnetics, 6, pp.177-188, 1985) reported that corneal endothelial abnormalities were observed after a 4-hour exposure of anesthetized monkey eyes to 2.45GHz CW. We have traced their experimental study without anesthetization. Although we irradiated with power density exceeding the threshold of 30mW/cm2 obtained by them, we could not observe the same abnormalities as they did.

Physical optics (PO) is an approximation method for high-frequency scattering and diffraction problems. But PO fields are inaccurate in the shadow region where the source is screened by the scatterer. It has been difficult to extract the mechanism of this error because PO includes numerical integration. In 2-D problems, PO fields are analytically and accurately expressed in terms of PO equivalent edge currents (PO-EECs) which represent the leading contributions of PO original integration. Comparison of PO in this form and geometrical theory of diffraction (GTD) which gives accurate fields in the shadow region, clarifies the cause of PO errors. For a scatterer with a corner, PO errors are mainly due to the rays emanating from the invisible edges. For a curved surface scatterer, the contributions penetrating the scatterer are small and main PO errors generally consist in PO-EECs itself.

This paper studies the effect of frequency re-using patterns on the channel capacity in the forward link of orthogonal code division multiple access (CDMA) cellular systems. The received carrier-to-interference ratio (CIR) determined by computer simulation shows that re-using the same frequency channel on every third sector (3-sector layout) provides superior channel capacity than does every-sector re-use (1-sector layout).

The radiation patterns of a circularly polarized GPS microstrip disk antenna mounted on the roof of a car are analyzed using UTD. Based upon the excellent agreements between the calculated and the measured results in all the observation directions, the effects of the antenna location upon radiation patterns are discussed in detail. As the distance between the antenna and the edge decreases, the gain in the low elevation angle on the same side as the edge considerably decreases. The effects of the earth are also extracted. They cause the fine ripples in the low elevation angle, though they are negligible in macroscopical view. Furthermore, the validity of the simple design neglecting the earth and the plates other than roof is investigated. The errors are localized at low elevation angle. The results obtained in this paper are useful in the design of the general antennas for mobile communication.

This paper presents an optimal filtering algorithm using the covariance information in linear continuous distributed parameter systems. It is assumed that the signal is observed with additive white Gaussian noise. The autocovariance function of the signal, the variance of white Gaussian noise, the observed value and the observation matrix are used in the filtering algorithm. Then, the current filter has an advantage that it can be applied to the case where a partial differential equation, which generates the signal process, is unknown.

The performance of parallel combinatory spread spectrum (PC/SS) communication systems in the frequency-nonselective, slowly Rayleigh fading channel is studied. Performance is evaluated by symbol error rate using numerical computation. To overcome the performance degradation caused by fading, we also studied the effects of selection diversity and Reed-Solomon coding applied to the PC/SS system. As a result, a remarkable improvement in error rate performance is achieved with Reed-Solomon coding and diversity technique. The coding rate for the maximum coding gain is almost a half of that in the additive white gaussian noise channel.

This paper describes the relaxation-based algorithms with the dynamic partitioning technique for bipolar circuit analysis. In this technique, a circuit is partitioned dynamically based on the consideration of the operating region of specified bipolar devices. This technique has been used already in the waveform relaxation method. In this paper, the dynamic circuit partitioning technique is implemented in the Iterated Timing Analysis (ITA). First, the dynamic partitioning method and its validity are described. Next, the present ITA is applied to the transient simulation of several digital bipolar circuits and compared with the waveform relaxation method.

A high-efficiency air cooling system is one of the keys to achieving high throughput in an ATM switching system for Broadband ISDN. Our approach is to cool the multichip modules plugged into a planar packaging system by using a two-phase thermosyphon cold-plate with an air-cooled condenser. Physically separating the cold-plate and the air-cooled condenser and connecting item by small diameter pipes is the key to applying this cooling technology to large planar packaging systems to increase volumetric packaging densities. Furthermore, thermosyphon technology allows the heat transfer process to operate without any external pumping power. Therefore this cooling system is regarded an extended high-performance air cooling system. The optimum structure was investigated while focusing on ways to reduce the external thermal resistance. The external thermal resistance between the system's cold-plate and air inlet was measured to be 0.21 K/W at an air velocity of 2 m/s and a cooling duty of 150 watts. Using this external thermal resistance value, we simulated the cooling characteristics of an MCM containing a 44 array of 10-mm-square LSI chips on an alumina substrate measuring 100100 mm. For an allowable temperature rise of 60, simulated thermal resistance was 6 K/W at an air flow of 2 m/s. This allows a power dissipation of more than 160 watts per MCM and a heat flux of 1.6 W/cm2. This system will extend the applicability of air cooling to power levels generally considered to lie in the domain of liquid cooling, and thus to the ATM switching nodes for B-ISDN.

A very-high-speed ten-neuron analog neural network LSI chip is fabricated for the first time using super self-aligned Si bipolar process technology. The LSI consists of ten neurons and 100 electrically modifiable synaptic weights. The neural network nonlinear mapping function to solve the four-bit parity problem is successfully demonstrated at 150 mega-patterns/sec. The operation speed of this neural network is, to the best of the authors, knowledge, the fastest yet reported.

Data of system parameters of real systems have some uncertainty and they should be given by sets (or intervals) rather than fixed values. To analyze and design systems contaning such uncertain parameters, it is required to represent and treat uncertainty in data of parameters, and to compute value sets of characteristic polynomials and transfer functions. Interval arithmetic is one of the most powerful tools to perform such subjects. In this paper, Polygon Interval Arithmetic (PIA) on the set of polygons in the complex plane is considered, and the data structure and algorithms to execute PIA efficiently is proposed. Moreover, practical examples are shown to demonstrate how PIA is useful to compute the evaluation of value sets.

In implementing the future Personal Communication Services (PCS), providing a system allowing simultaneous access by many subscribers is of utmost importance. The study of CDMA, as a candidate for the radio access method is being promoted for this purpose. Increasing the CDMA system capacity is determined by; the selection of a spread code having an excellent correlation characteristic; the interference cancellation method and; the method for controlling the power accordance with the near-far problems. In this paper we considered the cellular system, and have analyzed the correlation characteristic by using the PN or Walsh code as the innercell spreading code and the PN or Gold code as the intercell spreading code. We have also analyzed the sysytem capacity in terms of the correlation characteristics for different combinations of these spreading codes. It has been clarified as a result that 40 subscriber channels can be accommodated per cell by using the Walsh code and PN code as the innercell and intercell codes for the forward link (the Base Station (BS) to the Personal Station (PS)) and the PN code as both the innercell and intercell codes for the reverse link (the PS to the BS).

Let S(n) be a space constructible function such that S(n) log n. In this paper, we show that AuxSpTu (S(n),T(n)) NSPACE (S(n)log T(n)), where AuxSpTu (S(n),T(n)) is the class of languages accepted by nondeterministic auxiliary pushdown automata operating simultaneously in O(S(n)) space and O(T(n)) turns of the auxiliary tape head.

C-V and I-V characteristics of an n-MOSFET with Si-implanted gate-SiO2 of 50 nm are analyzed by using a test device with large equal channel width and length of 100 µm, and discussed for realizing a large hysteresis window of threshold voltage. Interface trap densities change logarithmically from 31010 to 11012cm2eV1 as the Si-dose at 25 keV increases from zero to 31016cm2. Threshold-voltage changes caused by 25 keV implantaions are as high as 0.2 V. Effective mobilities (subthreshold swings) change from 600 (0.10) to 100 cm2/Vs (0.26 V/decade) as the Si-dose increases from 0 to 31016 cm2 at 25 keV, and both parameters are related with the change of interface trap densities. There is a close relationship between the hysteresis windows of gate current and threshold voltage, and the largest threshold voltage window in a low gate voltage region is obtained for the MOSFET with Si-implantation at 25 keV/31016 cm2.

The frequency characteristics of whole-body averaged specific absorption rates (SARs) in a human model exposed to a near field of an electric dipole or a magnetic dipole are calculated, using a finite-difference time-domain method. The dependences of the characteristics on the orientation of the dipole and on the distance from the source to the model are investigated. It is shown that the resonant peak of the SAR that appears in the E-polarized far-field exposure is observed only when the source is E-polarized and is located at 80cm, while the peak vanishes or is not noted when the source is located at 40cm and 20cm nor when it is H-polarized. The relationships between the whole-body averaged SARs and the incident electromagnetic field strengths are also investigated. It is suggested that the spatially-averaged value of the dominating component between the electric field and the magnetic field over the space where a human body would occupy provides a relevant measure to estimate the whole-body averaged SAR of a body in the vicinity of a small radiation source.

Electromagnetic power absorption in multilayered tissue media including anisotropic muscle regions whose principal dielectric axes (that is, muscle fibers) have various directions are analyzed by using 44 matrix method. Numerical calculations in 10kHz-10MHz show the effects of orientation of muscle fibers and polarization of incident wave on absorbed power density in tissues.

In this paper, a new structure which is useful for the detection of multiple sinusoids is presented. The proposed structure is based on the direct form second-order IIR notch filter using simplified adaptive algorithm. It has been shown that the convergence characteristics of the proposed structure are much improved compared with the previously proposed structure. A cascaded adaptive notch filter using the proposed second-order section is also shown. It takes multiple sinusoids corrupted by white Gaussian noise and produces the individual sinusoids at each of the outputs. The results of computer simulation are shown which confirm the theoretical prediction.

A pseudoinverse rule, one of major rule to determine a weight matrix for associative memory, has large capacity comparing with other determining rules. However, it is wellknown that the rule has small domains of attraction of memory vectors on account of many spurious states. In this paper, we try to improve the problem by means of subtracting a constant from all diagonal elements of a weight matrix. By this method, many spurious states disappear and eigenvectors with negative eigenvalues are introduced for the orthocomplement of the subspace spanned by memory vectors. This method can be applied to two types of networks: binary network and analog network. Some computer simulations are performed for both two models. The results of the simulations show our improvement is effective to extend error correcting ability for both networks.

This paper discusses the effect of random errors in power meter readings by the six-port reflectometer. By means of six-port techniques, the determination of the reflection coefficient (Γ) of a divice under test is reduced to the problem of finding a common intersection of three circles in the complex plane. Since the intersection usually forms a cluster due to the effect of measurement error, the extraction of a single value from the cluster including the radical center of the three circles is required. Two types of methods are presented for determining Γ. One uses a linear solution for the radical center, and the other is a statistically based nonlinear solution. In order to improve measurement accuracy, the effect of random errors in the sidearm power meter readings and due to the influence of the q-point locations are investigated for each method. By adding a random variation of 0.5% onto each of the three port power ratios, the variance distributions of Γ over the entire area of the Smith chart are simulated for comparison of these two solutions. The three dimensional variance distribution chart reveals that only the nonlinear solution suffers a variance increase shown as a ridgelike peak along the lines of centers of the three circles. As a result of computer simulations, it is clarified that the reflectometer has the property of measurement accuracy dependence on the value of Γ. A new type of six-port model is suggested, which is unlikely to be affected by random errors in the nonlinear solution.

This paper proposes high-performance multiprocessor implementation for real-time one-dimensional (1-D) statespace digital filters (SSDFs). The block-state realization of SSDFs (BSRDF) is suitable for their high speed realization and gives the characteristics of high accuracy. Previously we proposed a VLSI-oriented highly parallel architecture for BSRDF. For the purpose of speeding up and reducing hardware complexity, the distributed arithmetic, of which processing time depends only on word length, is applied to this architecture. It is implemented as a 2-D SIMD processor array, and the processor consists of n homogeneous processing elements (PEs), n being filter order. The high sampling rate of one or more hundred MHz becomes possible for high filter order. Moreover, the number of I/O data per processor can be a small fixed value for any filter order, and the number of gates can also be smaller than that in the case of using multiplier. Consequently, this proposed system can be implemented easily even in the present VLSI environment.