We give an explicit formula for the number of n-variable clique function in terms of the parameters based upon the numbers of intersecting antichains of the lower half of the n-cube. We present the numbers of clique functions with up to seven variables through computer evaluation of the parameters.

This paper discusses a design method for two-dimensional (2-D) periodically time-variant digital filters (PTVDFs) whose filter coefficients vary periodically. First, 2-D periodicities for a variation of filter cefficients are considered, from which two and four-phase variations of coefficients are shown to be suitable for practical applications. Then, the input-output relation (transfer function) for 2-D separable-denominator (SD) PTV DFs is derived, which results in a linear combination of the baseband input signal and its modulated versions. Finally, in order ro approximate given filter specifications, the structure for 2-D SD PTV DFs is given and a design method is proposed. It is shown that, compared with the 2-D SD time-invariant DFs, approximation error can be reduced with the proposed SD PTV DFs.

In this paper, the evaluation of a hybrid acquisition performance has been considered for the pilot signal in direct sequence code division multiple access (DS/CDMA) forward link. The hybrid acquisition is introduced by the combination of two schemes, parallel and serial acquisitions. The mean acquisition time of the hybrid acquisition scheme is derived to consider both case 1 (the correct code-phase offsets ae included in one subset) and case 2 (the correct code-phase offsets exist at the boundary of two subsets), which are caused by the distribution of the correct code-phase offsets between two subsets. Detection, false alarm, and miss probabilities are derived for the cases of multiple correct code-phase offsets and multipath Rayleigh fading channel. Results are provided for the acquisition performance with respect to system design parameters such as postdetection integration length in the search and verification modes, subset size, and number of I/Q noncoherent correlators. Also, comparision between hybrid acquisition and parallel acquisition under the same hardware complexity is provided in terms of the minimum mean acquisition time.

A new cost function based on multi-band decomposition of the estimation error and application of a different step-size for each band is used in connection with the least-mean-square criterion to improve the fidelity of estimates as compared to those obtained with conventional least-mean-square adaptive algorithms. The basic new idea is to trade off time and frequency resolutions of the adaptive algorithm along the frequency domain by using different step-sizes in the analysis of distinct frequencies in accordance with the frequency-localized statistical behavior of the imput signal. The mathematical background for a stochatic approach to the multi-band decomposition-based scheme is presented and algorithms with fixed and variable step-sizes are derived. Computer experiments compare the performance of multiband and conventional least-mean-square methods when applied to system identification.

This paper describes a method to distinguish phase noise and amplitude noise from total oscillator noise in circuit simulation, and derives general relationships between periodic time-varying transfer functions for oscillators and phase and amplitude noises.

Introducing a mathematical model of noise in stereo images, we propose a new criterion for intelligent statistical inference about the scene we are viewing by using the geometric information criterion (geometric AIC). Using synthetic and real-image experiments, we demonstrate that a robot can test whether or not the object is located very far away or the object is a planar surface without using any knowledge about the noise magnitude or any empirically adjustable thresholds.

In this letter, the absolute exponential stability result of neural networks with asymmetric connection matrices is obtained, which generalizes the existing one about absolute stability of neural networks, by a new proof approach. It is demonstrated that the network time constant is inversely proportional to the global exponential convergence rate of the network trajectories to the unique equilibrium. A numerical simulation example is also given to illustrate the obtained analysis results.

Recently, the number of users utilizing mobile communication services has increased greatly in many information and communication fields. In the future, the number of mobile communication system users will increase even faster, until the rate of diffusion ultimately reaches that of telephones. The day that each person has his own portable mobile terminal is not so far off. Moreover, the systems will not only be used as telephones but also as mobile computing for multimedia information. Digitalization technologies of mobile communication systems needed to realize such mobile computing will be introduced in this paper.

Given the tremendous growth in the cellular phone system and the Personal Hadny-phone System (PHS), it is to be expected that demands for mobile computing using those wireless infrastructures, that is mobile computer access, will dramatically increase. This paper describes high-quality and high-speed data transmission technology for PHS mobile computing and current PHS data transmission standardization activities. Furthermore, wireless agent communication and a service example are presented together with the concept of background communication for the coming wireless multimedia services.

Within the framework of a previously proposed vision system, a new part-segmentation algorithm, that breaks an object defined by its contour into its constituent parts, is presented. The contour is assumed to be obtained using an edge detector. This decomposition is achieved in two stages. The first stage is a preprocessing step which consists of extracting the convex dominant points (CDPs) of the contour. For this aim, we present a new technique which relaxes the compromise that exists in most classical methods for the selection of the width of the Gaussian filter. In the subsequent stage, the extracted CDPs are used to break the object into convex parts. This is performed as follows: among all the points of the contour only the CDPs are moved along their normals nutil they touch another moving CDP or a point on the contour. The results show that this part-segmentation algorithm is invariant to transformations such as rotation, scaling and shift in position of the object, which is very important for object recognition. The algorithm has been tested on many object contours, with and without noise and the advantages of the algorithm are listed in this paper. Our results are visually similar to a human intuitive decomposition of objects into their parts.

This paper describes a nondestructive measurement method for complex permittivity of dielectric plates at 2 GHz, using a cylindrical cavity resonator. The resonator is divided into two parts at the center. Two dielectric plates are symmetrically loaded around the center of the cavity. These plates have high permittivity of 45. A dielectric plate specimen is clamped with these halves. The values of relative permittivity ε and loss tangent tanδ of the specimen are obtained from the resonant frequency and unloaded Q-value of TE011 mode. Measured results of various materials are compared with those values obtained at 3 and 10 GHz by other cavity resonator method. An edge effect is taken into account by a reference method, using measurement data of a sapphire plate. The errors of the present method are smaller than 1% and 2-310-5 for ε and tanδ, respectively.

The high resolution CRT displays used for computer monitor and high performance TV often produce a pattern of bright and dark stripes on the screen called a moire pattern. The elimination of the moire is an important consideration in the CRT design. In this paper, we propose a method for evaluating a moire pattern based on the measurement data of the electron beam distribution. (1) We describe a mathematical expression of the process whereby a moire pattern is produced. By applying the electron beam measurement data into the formulae, precise value of the period and the contrast of a moire are calculated from the actual data of the electron beam profile and the distribution of apertures of the shadow mask. (2) The visibility of the moire is evaluated by plotting the calculation results on the contrastperiod plane, which consists of visible and invisible moire pattern regions based on experimental results of the psychological tests. (3) In addition to the analysis by calculation, the visibility of moire patterns can be visually examined by simulating moire patterns using the same data as above calculation. Since not only fundamental design parameters such as a shadow mask pitch and a scanning line pitch but also details of an electron beam profile such as a distortion or an asymmetry can be examined, a newly developed method contributes the efficiency of the CRT design.

This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

Electroluminescent (EL) devices with mixed single layer that consist of fluorescent dyes, distylylbiphenyl derivative (DPVBi) and triphenylamine derivative (TPD), are studied. Blue light emission was observed from the device with DPVBi and TPD. White emission over 2,500 cd/m2 was observed from the devices with mixed single layer of DPVBi, TPD and dicyanomethylene derivative (DCM).

In order to improve luminance and luminous efficiency of color ac plasma displays (PDPs), absorption characteristics of ultraviolet rays were investigated for dielectric materials from a viewpoint of protecting layer of ac PDPs. The double protecting layer of MgF2 and MgO is clarified to be excellent property to improve the optical performance of color ac PDPs. The double protecting layer of MgF2 and MgO was applied to the barrier-rib electrode color ac PDPs and resulted in high luminance and luminous efficiency of 1030 cd/m2 and 1.0lm/W, respectively.

This paper describes a new multiple DmB1C (Differential m Binary 1 Complement insertion) /DmB1M (Differential m Binary with 1 Mark insertion) coding scheme for high-speed optical multiplex transmission. The coding scheme has the characteristics of small consecutive identical digits and a good balance between marks and spaces. Furthermore, it has also good synchronization characteristics and higher flexibility for extension to high capacity transmission than the conventional mB1C or DmB1M coding schemes. We describe a design methodology for a multiplex transmission system using the proposed coding scheme, and verify the characteristics of the proposed coding scheme using an experimental setup of a 2.8 Gbit/s serial optical interconnection circuit, which has 16 parallel 156 Mbit/s inputs. The coding scheme realizes transmission systems with simple analog circuit configuration, and small digital circuit complexity with wide dynamic range and good mark ratio tolerance.

Obradovic and Parberry showed that any n-input k-ary function can be computed by a depth 4 unit-weight k-ary threshold circuit of size O(nkn). They also showed that any n-input k-ary symmetric function can be computed by a depth 6 unit-weight k-ary threshold circuit of size O(nk+1). In this paper, we improve upon and expand their results. The k-ary threshold circuits of nonunit weight and unit weight are considered. We show that any n-input k-ary function can be computed by a depth 2 k-ary threshold circuit of size O(kn-1). This means that depth 2 is optimal for computing some k-ary functions (e.g., a PARITY function). We also show that any n-input k-ary function can be computed by a depth 3 unit-weight k-ary threshold circuit of size O(kn). Next, we show that any n-input k-ary symmetric function can be computed by a depth 3 k-ary threshold circuit of size O(nk-1), and can be computed by a depth 3 unit-weight k-ary threshold circuit of size O(knk-1). Finally, we show that if the weights of the circuit are polynomially bounded, some k-ary symmetric functions cannot be computed by any depth 2 k-ary threshold circuit of polynomial-size.

This paper describes the performance of a video communication system over mobile radio channels. Mobile channel quality changes rapidly due to various factors. When compressed video data is transmitted through these channels, it is indispensable to employ an error control scheme because reconstructed video quality is seriously degraded by channel error. To control this error, an automatic repeat request (ARQ) scheme is often employed, however, this incurs a cost. The benefit of a non-degraded reconstructed video sequence is offset by the transmission delay due to ARQ retransmission. We apply to a video communication system a selective-repeat ARQ which is combined with the coding control scheme to reduce the transmission delay. We evaluate the quality of the reconstructed video sequence and transmission delay using computer simulations and make clear its applicability over Rayleigh and Nakagami-Rican fading channels and intersymbol interference.

A new Neural Network Equalizer (NNE), employing multilayer feedforward neural network, is proposed as a compensation method for nonlinear and multipath distortion that arises from FTTA (Fiber To The Air) system. If a signal in a channel is affected by nonlinear distortion, the conventional Decision Feedback Equalizer (DFE) finds difficulty in perfect compensation of it. To compensate for nonlinear distortion as well as multipath distortion, an equalizer, employing neural network, is investigated. A new neural network equalizer, yielding a cubic function as unit output function, is proposed in order to compensate the nonlinear distortion effectively. We also propose an initial weights of neural network for preventing from local minimum. Computer simulation results show that the compensation performance of the new NNE is superior to the conventional DFE and the conventional NNE.

This paper proposes a protocol to support mobile hosts in IPv6 by introducing a new addressing architecture and a new hop-by-hop option. This protocol also allows a mobile host to communicate with another host via a firewall machine which drops packets from untrustworthy hosts. The new addressing scheme is based on the separation of the identifier and the location of a mobile host. This is a straightforward implementation of the basic concept of VIP, a protocol providing seamless mobility in IPv4. The new hop-by-hop option of IPv6 allows a firewall machine to authenticate the source host of the forwarded packet with negligible overhead. The author plans to implement this protocol on several operating systems in the near future.