This paper discusses a new image resolution conversion method which converts not only spatial resolution but also amplitude resolution. This method involves considering impulse responses of image devices and human visual characteristics, and can preserve high image quality. This paper considers a system that digitizes the multilevel input image with high spatial resolution and low amplitude resolution using an image scanner, and outputs the image with low spatial resolution and high amplitude resolution on a CRT display. The algorithm thus reduces the number of pixels while increasing the number of brightness levels. Since a CRT display is chosen as the output device, the distribution of each spot in the display, which is modeled as a Gaussian function, is taken as the impulse response. The output image is then expressed as the summation of various amplitudes of the impulse response. Furthermore, human visual perception, which bears a nonlinear relationship to the spatial frequency component, is simplified and modeled with a cascade combination of low-pass and high-pass filters. The output amplitude is determined so that the error between the output image and the input image, after passing through the visual perception filter, is minimized. According to the results of a simulation, it is shown that image quality can be largely preserved by the proposed method, while significant image information is lost by conventional methods.

To study the biological effects of the ion-current commonly found under ultra-high voltage DC transmission lines, a technique was developed to evaluate the human exposure to the ion-current field. This technique is based on numerical analysis using the boundary element method. The difficulty of handling the space charge in the calculation was overcome by assuming a lumped source ion-current. This technique is applicable to a three-dimensionally complex object such as a human body. In comparison with theoretical values, the accuracy of this technique was evaluated to be satisfactory for our purposes. It was then applied to a human body in an ion-current field. The distribution of the electric field along the body surface was obtained. The general characteristics of the field distribution were essentially the same as in those without space charges. However, it was found that the strength of the field concentration was significantly enhanced by the space charges. Further, the field exposure when a human body was charged by an ion-current was evaluated. As the charged voltage increases, the position of the field concentration moves from a human's head toward his legs. But the shock of micro spark increases. This technique provides a useful tool for the study of biological effects and safety standards of ion-current fields.

Nested relational models were proposed as natural extensions of the relational model to support new emerging database applications. Prototype implementations of nested relational database systems (NRDBSs) have been done by some research groups. However, there remain many research issues on nested relations. One important issue is query processing, in particular query optimization. In NRDBSs, efficient execution of queries involving hierarchical data structures inherent in nested relations is required. In this paper, we focus on two join-type operations on nested relations: nested join and embed, and propose an algorithm to derive a cost optimal execution sequence of nested joins and embeds for a given query graph. The cost optimality of the derived sequence is formally proved. The complexity of the algorithm is proved to be O(N 2), when N nested relations are included in the query graph.

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 plane wave diffraction by a two-dimensional parallel-plate waveguide cavity with partial material loading is rigorously analyzed for both the E and the H polarization using the Wiener-Hopf technique. Introducing the Fourier transform for the scattered field and applying boundary conditions in the transform domain, the problem is formulated in terms of the simultaneous Wiener-Hopf equations satisfied by the unknown spectral functions. The Wiener-Hopf equations are solved exactly via the factorization and decomposition procedure leading to the formal solution, which involves branch-cut integrals with unknown integrands as well as infinite series with unknown coefficients. Applying rigorous asymptotics with the aid of the edge condition, the approximate solution to the Wiener-Hopf equations is derived in the form suitable for numerical computations. The scattered field inside and outside the cavity is evaluated by taking the inverse Fourier transform together with the use of the saddle point method. Numerical examples of the radar cross section are presented for various physical parameters, and the far field backscattering characteristics of the cavity are discussed in detail. Some comparisons with a high-frequency technique are also given to validate the present method.

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.

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.

This paper presents a mathematical formulation of a data path allocation and floorplanning problem using the mixed integer linear programming, and shows some experimental results. We assume that a data flow graph and the scheduled result are given in advance. The chip area and total wire length are used for the quality measures of the solution for the problem. This method is applied to some examples, and compared with the other method reported previously in the points of the solution and computation time.

Transmission characteristics of CPW bends having various curvatures and a fixed bend angle were measured. It was found that the transmission level shows dips at some particular frequencies, and that the dips are less pronounced as the radius of curvature becomes larger.

This paper discusses the potential benefits of H0-based ISDN. By providing widespread H0 (384kb/s) call services, much like today's telephone systems, it should be possible to bring multimedia public communication services to the general public. Small distributed switching systems and reuse of existing metallic loops will contribute to its economical construction and rapid expansion into general use. System-on-a-chip technology, expected to appear soon, will make the necessary small switching systems cost-effective. The short loops resulting from the distribution will allow Hl-band (1.5/2.0Mb/s) metallic loops to be used. In terms of function, the distributed switching nodes will permit node-by-node customization, which will make switching systems simple and flexible. The proposed node-by-node customization will allow subscribers in each different node to choose they prefer. H0-based ISDN will provide various type of nodes, supporting various types of subscriber loops, whereas present public networks enforce standardized subscriber loops. Furthermore, when customized subscriber switching systems accommodate star-LAN interfaces as subscriber loops, the public network will be able to provide LAN services in a closed area as part of the public network services. The LAN users will be able to converse with ordinary residential subscribers through H0-calls. This will lead to the integration of LANs and public networks.

We propose a beam tracing frame which shifts together with either the guiding structure or the beam propagation in optical circuits. This frame is adaptive to the beam propagation analysis based on the finite-element method and can reduce the computational window size.

An experimental SAR (Specific Absorption Rate) estimation system based upon the thermograph method using a thermograph camera and newly developed homogeneous dry-phantom human models are presented. Experiments are conducted using this system and UHF fields to obtain SAR distributions in the human head irradiated by hand-held portable radios. Experiment results show that the estimated peak SAR's due to the radiation waves from radios of 1W transmitting power are lower than 2W/kg and so conform to the recommendations of the radio-frequency radiation safety guidelines. The developed system enables the surface SAR distributions on the phantom model to be precisely estimated; a function not available with the original system. System parameters required for providing precise estimations are discussed first, and then experiments are conducted to estimate SAR's in the human head exposed to a UHF hand-held portable radio's near field. Finally, estimated data are examined from the viewpoint of radio-frequency exposure safety guidelines.

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.

A new design methodology is proposed and analyzed for the design of ternary logic systems. In the new ternary logic systems, no conversions among radices are required and only the two-state ternary literals associated with the ternary signals are transmitted in the whole system. With the new design methodology, the ternary systems can be realized by the dynamic CMOS logic circuits which are simple and fully compatible with those of the conventional binary logic circuits in process, power supply, and logic levels. A new dynamic differential logic called the CMOS Redundant Differential Logic (CRDL) is also developed to increase the logic flexibility and the circuit performance. Using the new design methodology and the CRDL circuits, the multiplier with redundant binary addition tree is designed in both non-pipelined and pipelined systems. The experimental chip has been fabricated and measured, which successfully verifies the correctness of the logic functions and the speed performance of the designed circuits.

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.

A novel analysis method of the intermodulation (IM) and the noise power ratio (NPR) of multiple-carrier amplifiers is descrided. This method, based on Discrete Fourier Transform, allows an accurate calculation of IM and NPR of the amplifier having multiple carriers by directly using measured single-carrier amplitude and phase characteristics. This method has an outstanding feature in that it can be applied to the general case of n carriers having an arbitrary power level as long as frequency-dependence of amplitude and phase characteristics is negligibly small. Applying this method to the linearized amplifier, a good agreement between measured and calculated results for IM3, IM5, and NPR has been obtained for operation from linear up to saturation, which shows this method would be a good candidate for calculating IM and NPR of multiple-carrier amplifiers.

This paper describes a nondestructive measurement method for complex permittivity of dielectric material at pseudo microwave frequencies. The resonator used in this study has a cylindrical cavity filled with a sapphire material of a well known complex permittivity. The resonator is divided into two parts at the center. A dielectric substrate specimen is clamped with these halves. Relative permittivity εand loss tangent tan δ of the specimen are obtained at 3 GHz using the TE011 resonance mode. The accuracy of the present method is evaluated through the comparison of the measured values by the new method with those at around 10 GHz by the conventional empty cavity resonator method. The errors of measurements are smaller than 1% and 1105 for εand tan δ, respectively.

In this paper, we discuss an application of range Doppler imaging to measurement of reflected wave intensity from a moving object without using an anechoic chamber. The wave intensity reflected from a metal plate moving in the horizontal direction toward the antenna is typically 40-50 dB higher than that in the case without using the plate, and the estimated radar cross sections for a metal plate and sphere show good agreement with the theoretical value. The measurement of wave absorption by the present method suggests that frequency characteristics of the observed reflection loss are in close agreement with those of the calculated loss. These results show the reliability of the present experimental system and suggest that the method is applicable to wave reflection measurement not in an anechoic chamber but in an ordinary laboratory room.