Research in radar polarimetry is hampered by shortcomings of the conventional formulation of polarimetric backscatter concepts. In particular the correct form of the Sinclair backscatter matrix under changes of polarization bases is derived from the antenna voltage (energy transfer) equation yielding the erroneous impression that radar polarimetry is a mongrel between scattering behavior and network performance. The present contribution restores logical consistency in a natural way by introducing the concept of an antilinear backscatter operator. This approach decouples scattering process and network performance, illuminates matrix analytical properties of the radar backscatter matrix and highlights characteristic states of polarization.

Frequency demodulation of a single side-band signal with a carrier is discussed and a new demodulation method is proposed. Compared with the conventional RZSSB (real zero single-side band) demodulator, there are no even-order distortions in the demodulated output signal of the proposed method and the third-order distortion can be canceled very easily without any Hilbert transformer as is required in the conventional RZSSB demodulator. Since the carrier can be reproduced completely from the input signal by the proposed method, it can be used for not only an RZSSB signal but also a full-carrier SSB signal or a low-carrier SSB signal. Compared with transmitting an RZSSB signal, it more efficiently transmits a low carrier SSB signal since the carrier does not include any useful information. By this means, the transmission efficiency can be greatly improved by adopting the proposed method.

In practical applications of the artificial boundary surfaces, such as corrugation and strips on a grounded dielectric slab, the surfaces have finite sizes. The diffraction fields from anisotropic surface of this kind can not be calculated using conventional diffraction coefficients. In this paper, uniform diffraction coefficients for the strips on a grounded dielectric slab are given in the sense of physical optics, as functions of incident angle, polarization and structural parameters of the surface. Firstly, the incident plane wave is decomposed into the two special polarization directions. Then uniform diffraction coefficients originally derived for isotropic surfaces with arbitrary impedance can be applied for each polarization component. Finally, expressions for the diffraction coefficients from the anisotropic surface are given as the sum of those for two polarization components. The validity of the diffraction coefficients is verified theoretically and experimentally.

The growth characteristics of a two-dimensional Cherenkov laser composed of a planar relativistic electron beam and a parallel plate waveguide one plate of which is loaded with a nonlinear dielectric sheet are analyzed. The permittivity of the nonlinear dielectric sheet becomes inhomogeneous due to the Kerr effect as the electromagnetic wave grows along the waveguide. For the analysis of the electromagnetic fields in the nonlinear dielectric sheet, it is replaced by a number of thin dielectric layers each of which is assumed to be homogeneous. From numerical analysis, it is found that just a few homogeneous layers for the nonlinear dielectric sheet are enough to get the same results as obtained previously by means of the finite element method. This is because the variation of the permittivity across the nonlinear dielectric sheet is as small as within 10% of the linear permittivity of the nonlinear material. Thus the multilayer approximation method is found to be more simple and more efficient for the analysis of the Cherenkov laser loaded with a Kerr-like medium than the finite element method.

In this paper, the diffusion parameter-values in the K+-ion diffused waveguides made by diluted KNO3 with NaNO3 in the soda-lime glass, which are determined from measured values of the effective index, are presented together with a simple method for the determination. The surface-index changes are measured for the waveguides by KNO3 melts with 75%-, 50%- and 30%-dilutions (weight ratio), and for comparison purpose, also by the pure KNO3, and the dependence of the index-profile on the dilution of KNO3 in the ion-source melt is shown. Change of the two-dimensional index profile in the diffused channel waveguide with the KNO3-dilution is also shown, which is calculated with the measured diffusion parameters.

The dielectric rod waveguides with corrugation consisting of nonintegral-ratio period waves are investigated numerically. The leakage characteristics of HE11-type wave in the waveguide is analyzed by applying Yasuura's method. The complex propagation constants and the far field patterns are presented. The radiation pattern of a fabricated waveguide with corrugation agrees well with the calculated value. The dependence of radiation characteristics on the corrugation form is discussed. It is shown that the leakage directions and the intensity of leaky waves are controlled independently one another. The radiation pattern can be synthesized by choosing the geometric parameters of the corrugation properly.

This paper presents a theoretical study on transmission properties of bent optical waveguides of uniaxial anisotropic material. The waveguiding structure consists of two parallel straight slab waveguides connecting by an oblique section. By arranging the direction of the optical axis in the oblique section so that the wave normal always points to the same direction throughout the waveguiding structure, low loss transmission can be realized. The analysis of wave propagation through the structure is based on the finite difference beam propagation method. Numerical results indicate that by optimally arranging the direction of the optical axis in the oblique section power coupling coefficients better than 95% can be obtained for any tilt angle of the oblique section when the tilt angle is smaller than 2 degrees. Some field distributions are also presented along the waveguiding structure.

A method is proposed for locating large gas leaks in subscriber cable networks composed of different type cables and/or branch cables that uses pressures periodically measured at several points. Theoretical pressure curves corresponding to these measured pressure curves are calculated using a model representing the actual cable network. These curves are called the calculated pressure curves. The position of the leak is varied in the calculation model and where the measured and calculated pressure curves coincide the most, the leak position in the calculation model indicates the estimated leak position. The calculated pressure curves are based on the Laplace transform and an analogy between the pneumatic characteristics in cable networks and the electrical characteristics in electrical transmission networks. An experiment using a cable network about 910m long resulted in a location error of less than 30m.

Discrete higher-order modes of stripline, both proper and leaky, as well as its continuous spectrum are conceptualized and quantified by a full-wave integral operator formulation through complex analysis in the axial Fourier-transform plane. Poles associated with the parallel-plate background environment lead to branch points in the axial transform plane. A criterion for choice of associated branch cuts to restrict the migration of poles in the transverse transform plane is identified. The higher-order discrete modes are both bound (proper), with a low-frequency cutoff, and leaky (improper). The higher-order proper mode has a propagation constant very nearly equal to that for the TM parallel-plate mode. Distributions of the continuous-spectrum currents appear to consist of a smooth transition from those of the highest propagating proper discrete mode, as might be expected physically. The continuous spectrum is dominated by the propagating portions associated with any TM background modes (poles) which are above cutoff, and in fact by spectral points in a region very near to the branch point.

We propose a new high-performance message router for k-ary n-cube multicomputer systems, called the Tokky router. The router utilizes a small number of queues at the outputs of its communication ports to allow fully adaptive routing, misrouting to prevent deadlocks and randomization to prevent livelock. Uncongeste network performance is improved by the inclusion of the packet expressway. Accurate models are developed to predict the switch and buffer performance of routers for varying radix and dimension and these models can be used in the design of routers for networks other than those investigated here. The simulated performance of the router exceeds that of published results for oblivious routers and is equal to or exceeds those reported for other adaptive routers. These performance predictions are especially encouraging when the simplicity of the control structures required to implement the router are taken into consideration.

We present that event-transition diagrams are useful to analyze event concurrent response visually. Event-transition diagrams are dual for state-transition diagrams in graph theory. As an example of an usage of an event-transition diagram, a simple model of a railroad crossing is presented.

A folded short in parallel-plate waveguide is investigated using the Fourier transform and the mode-matching. A fast-converging series solution for scattering from the folded short is obtained and its characteristics are presented. Our solution for the E-plane short agrees well with measurements and is numerically more efficient than the existing moment-method solution. The presented scattering characteristics are useful for the design of the E- and H -plane shorts in rectangular waveguide.

Cellular Neural Networks (CNNs) are nonlinear dynamic array processors with mainly local interconnections. In most of the applications, the local interconnection pattern, called cloning template, is translation invariant. In this paper, an optimal ring-coding method for rotation invariant description of given set of objects, is introduced. The design methodology of the templates based on the ring-codes and the synthesis of CNN analogic algorithms to detect standing and moving objects in a rotationally invariant way, discussed in detail. It is shown that the algorithms can be implemented using the CNN Universal Machine, the recently invented analogic visual microprocessor. The estimated time performance and the parallel detecting capability is emphasized, the limitations are also thoroughly investigated.

This paper proposes a masked data transferring method for the write-back controlled disk cache system employing a fixed-length recording disk drive, enabling data transfer of discontinuous sectors on the same track between the cache and the disk. This paper also evaluates the method. In write-back controlled disk cache sytems, random write requests cause dirty data (write-pending data on a cache) on discontinuous areas on the cache. It is likely that several sectors on the same track become dirty. These dirty sectors must be written onto the disk according to the cache management scheme. In conventional data transferring methods between a disk cache and a disk drive, plural sectors can be transferred in one single operation when the sectors are adjacent, but discrete sectors must be transferred by individual operations. In the methods, an address of the head sector and number of sectors to be transferred are given to the transfer unit. For example, when two sectors on the same track are located closely but not adjacently, and data transfer is requested for those two sectors, the transfer operation for the second sector must be prepared after the first transfer had completed and before the second sector arrives under the disk head. Although the time for the head to pass by the uninterested sector is often too short for the software overhead for the first transfer to be completed and the second transfer to be prepared, which leads to an unwanted extra rotation of the disk. With the masked transferring method proposed in this paper, the micro program creates a bit-map specifying the target sectors to be transferred and passes it to the data transfer unit, enabling to transfer the discontinuous sectors without latency. The method was evaluated using OLTP warkloads. Results show an improvement in random I/O throughput of between 8% and 27%. The masked transferring method is adopted in Hitachi's A-6521 disk subsytems, shipped since December 1993.

The complex refractive indices n-jχ of typical magnetic fluids were evaluated for the sake of utilizing them as optical materials. Transmission and reflection spectra were measured in the wavelength range of 0.6-1.6 µm by using monochromators. Magnetic fluids were put into glass cells of 2.5-14-µm thickness for transmission measurement. Due to the absorption by magnetic fluids, the transmittance decreased notably with the increase of the sample thickness. The extinction coefficient χ was evaluated from the dependence of the transmittance on the sample thickness. χ was found to vary between 0.003 and 0.03 depending upon wavelength. The refractive index n was evaluated by fitting theoretical curves to the reflectances that were measured for various incident angles. n was found to vary between 1.6 and 1.7 depending slightly on wavelength. Since a magnetic fluid is a composite of ferrite particles and a solvent, the refractive index can be calculated by using the effective medium theory. The calculated value agreed well with the experimental value. Preliminary experiment of optical switching was also demonstrated by utilizing the mobility of a magnetic fluid.

In this paper, we present for the first time two three-dimensional analytical electrostatic Green's functions for shielded and open arbitrarily multilayered medium structures. The analytical formulas for the Green's functions are simply expressed in the form of Fourier series and integrals, and are applicable to the arbitrary number of dielectric layers. In combination with the complex image charge method, we demonstrate an efficient application to analyze microstrip discontinuities in a three-layered dielectric structure. Numerical results for the capacitance associated with on open-end discontinuity show good agreement with those from a previous paper and the effectiveness of using the analytical Green's functions to analyze three-dimensional electrostatic problems.

The rapid progress in semiconductor technology and chip mounting technology has made it possible to produce portable computes with high performance, such as notebook computers and PDAs. Portable computes can be used anytime and anywhere. By using the features of mobility, some cooperative works anywhere with multiple portable computers have been realized. However, present networks such as a wireless LAN or a public wireless network are too limited to permit portable computers to cooperate with each other. As the result, a new networking technology for portable computers has been highly requested. In this paper, we propose a novel network technology suitable for face-to-face communication, which we call "Wireless DAN" (Desk Area Network). Here, face-to-face communication is a communication between people who can directly see faces and hear voices with each other. In Wireless DAN, computers independently recognize the network configuration around them. Although present computer networks assume permanence and all computers must be registered before the system can be used, Wireless DAN enables a computer to communicate with computers nearby at any place the user goes without any complicated procedures or dedicated network equipment such as a base station. We also present a new support system for face-to-face cooperative work, which makes it possible to join or leave a meeting while it is in progress. We have developed an experimental system of Wireless DAN and the support system, which is comprised of notebook personal computers with an existing peer-to-peer infrared LAN card. The support system has been implemented using the functions provided by Wireless DAN and thus the system has been simplified. With the experimental system, we confirmed that Wireless DAN operates effectively for face-to-face communication.

In this work, a statistical analysis is performed for a simple constrained high-order Yule-Walker (YW) tone frequency estimator obtained from the first equation of the constrained high-order YW equations. Explicit expressions for its estimation bias and variance are efficiently derived by virtue of a Taylor series expansion technique. Especially, being explicit in terms of frequency, data length and Signal-to-Noise Ratio (SNR) value, the resulting bias expression can not be obtained by using the asymptotic analyses used for the parameter estimation methods. The obtained expressions are compared with their counterparts of the Pisarenko tone frequency estimator. Simulations are performed to support the theoretical results.

Information capture is a very desirable and important function in portable computers. The "Multimedia Notebook" is a portable tool for capturing information in multimedia format, which includes photos, voice, and handwritten memos. Recent portable units, sometimes called PDA (Personal Digital Assistants) or Communicators, have PIM (Personal Information Manager) software and some communication facility. Their purpose is to enlarge the desktop environment to follow the user outside the office. This is one application of portable equipment, however we felt that hand-held equipment can also be used for more general information capture. In the past, information capture was limited, because people had to carry bulky equipment to the information source. Recent portable computers that have the capability to handle still and motion pictures, voice, and handwritten drawings allow the implementation of more information capture capabilities. Capture of handwritten notes has already been implemented on portable equipment like PDAs. However, this application doesn't make the most of its potential. We feel that the Multimedia Notebook should integrate handwritten memos with pictures and voice. The advantage is that users can capture what they watch and hear easily in a variety of media for later review. The information in each medium complements the others. When arranging the recorded information, it is easy to use each medium efficiently. We have examined the human interface and designed it for user-friendliness and to be comparable to pen and paper. The prototypes also have a capture buffer which can operate continuously to capture voice and pictures that would otherwise be lost because of the user's delay in starting to record.

On a simple model, the quality of the security tag is simulated theoretically and experimentally. A simple correction makes both results correspond exactly and a simulation formula is provided. By using novel insulating film, a small-sized tag of high quality is developed.