In this paper, in order to control uncertain chaotic system, an adaptive fuzzy control (AFC) scheme is developed for the multi-input/multi-output plants represented by the Takagi-Sugeno (T-S) fuzzy models. The proposed AFC scheme provides robust tracking of a desired signal for the T-S fuzzy systems with uncertain parameters. The developed control law and adaptive law guarantee the boundedness of all signals in the closed-loop system. In addition, the chaotic state tracks the state of the stable reference model (SRM) asymptotically with time for any bounded reference input signal. The suggested AFC design technique is applied to control of a uncertain Lorenz system based on T-S fuzzy model such as stabilization, synchronization and chaotic model following control (CMFC).

Several subband array methods have been proposed as useful means to perform joint spatio-temporal equalization in digital mobile communications. These methods can be applied to mitigate problems caused by the inter-symbol interference (ISI) and co-channel interference (CCI). The subband array methods proposed so far can be classified into two major schemes: (1) a centralized feedback scheme and (2) a localized feedback scheme. In this paper, we propose subband arrays with partial feedback scheme, which generalize the above two feedback schemes. The main contribution of this paper is to derive the steady-state mean square error (MSE) performance of subband arrays implementing these three different feedback schemes. Unlike the centralized feedback scheme which can be designed to provide the optimum equalization performance, the subband arrays with localized and partial feedback schemes are in general suboptimal. The performance of these two suboptimal feedback schemes depends on the channel characteristics, the filter banks employed, and the number of subbands.

In this paper we show that the neuron filter is effective for relaxing the coefficient sensitiveness of the Hopfield neural network for combinatorial optimization problems. Since the parameters in motion equation have a significant influence on the performance of the neural network, many studies have been carried out to support determining the value of the parameters. However, not a few researchers have determined the value of the parameters experimentally yet. We show that the use of the neuron filter is effective for the parameter tuning, particularly for determining their values experimentally through simulations.

This short paper is a written version of one part of the plenary address given at the November 1999 NOLTA symposium held at the Hilton Waikoloa Village in Hawaii. I was invited by Professor Shin'ichi Oishi, a general vice-chairman of the symposium, to give a survey of some of my own research. I was happy to do that--in the context of a description of what Bell Labs.' research environment was like in its math center in the 1960's, and why I feel that today's young researchers are often too constrained in that they are typically not encouraged to try to do really interesting work. Here the emphasis is on only the origins of input-output stability theory.

An analytic equation was derived for the time jitter of digital NRZ signals due to inter-symbol interference in the PCB transmission lines loaded by DRAM chips which are located in uniform spacing. The inter-symbol interference is caused by a low-pass filtering effect of the loaded transmission line. Good agreements were observed between the equation and measurements with an average error of 17.5%.

In this paper, we shall construct mathematical theory based on the concept of set-valued mappings, suitable for available operation of network systems extraordinarily complicated and diversified on large scales. Fundamental conditions for availability of system behaviors of such network systems are clarified in a form of fixed point theorem for system of set-valued mappings.

TEM-mode electric field uniformity on the transverse plane that was perpendicular to a floor conductor of a GTEM (gigahertz transverse electromagnetic) cell, and the usable test volume in the cell, were evaluated both theoretically and experimentally at frequencies of up to 1 GHz. Electric fields in the GTEM cell were calculated by using the FD-TD (finite-difference time-domain) method. The fields were measured by using an optical E-field (electric field) sensor in order to confirm the calculation result. CISPR/A (CISPR: Comite International Special des Perturbations Radioelectriques) and IEC (International Electrotechnical Commission) SC77B proposed in their committee draft that the usable test volume was 0.6W 0.33h, where W and h were a width of the septum (inner conductor of the cell) and a distance between the septum and the floor conductor of the cell, respectively. We found that the usable test volume, i. e. the maximum width and height of an EUT, by the committee draft are reasonable and applicable for a GTEM cell.

Single crystal MnZn Ferrites are used as core materials for the reader of inductive magnetic heads. Magnetic phase homogeneity of the material is one of the parameters, which affects the quality of the devise. We used static magnetic measurements above the apparent Curie temperature of the Ferrite materials to determine the presence of such phases. High performance samples are non-magnetic at high temperature. In low performance materials, a small but non-zero spontaneous magnetization at high temperature indicates the presence of the second phase.

In this paper we consider a tensor-based approach to the analytical computation of higher-order expectations of quantized trajectories generated by Piecewise Affine Markov (PWAM) maps. We formally derive closed-form expressions for expectations of trajectories generated by three families of maps, referred to as (n,t)-tailed shifts, (n,t)-broken identities and (n,t,π)-mixing permutations. These families produce expectations with asymptotic exponential decay whose detailed profile is controlled by map design. In the (n,t)-tailed shift case expectations are alternating in sign, in the (n,t)-broken identity case they are constant in sign, and the (n,t,π)-mixing permutation case they follow a dumped periodic trend.

We propose hysteresis neural network solving combinatorial optimization problems, Box Puzzling Problem. Hysteresis neural network searches solutions of the problem with nonlinear dynamics. The output vector becomes stable only when it corresponds with a solution. This system does never become stable without satisfying constraints of the problem. After estimating hardware calculating time, we obtain that numerical calculating time increases extremely comparing with hardware time as problem's scale increases. However the system has possibility of limit cycle. Though it is very hard to remove limit cycle completely, we propose some methods to remove this phenomenon.

Most of the image restoration filters proposed so far include parameters that control the restoration properties. For bringing out the optimal restoration performance, these parameters should be determined so as to minimize a certain error measure such as the mean squared error (MSE) between the restored image and original image. However, this is not generally possible since the unknown original image itself is required for evaluating MSE. In this paper, we derive an estimator of MSE called the subspace information criterion (SIC), and propose determining the parameter values so that SIC is minimized. For any linear filter, SIC gives an unbiased estimate of the expected MSE over the noise. Therefore, the proposed method is valid for any linear filter. Computer simulations with the moving-average filter demonstrate that SIC gives a very accurate estimate of MSE in various situations, and the proposed procedure actually gives the optimal parameter values that minimize MSE.

This paper presents the design of low sidelobe single-layer slotted waveguide arrays. The Taylor distribution with -25 dB sidelobe level is synthesized in two orthogonal directions in the aperture. The multiple-way power divider consisting of a cascade of novel π-junctions is introduced; each π-junction, two-way power divider, is so designed as to accept unequal power dividing by adopting an offset window. The smooth Taylor distribution is realized at the output of the multiple-way power divider, which was originally developed only for uniform distribution. A model antenna for Taylor distribution is tested at 76 GHz. The measured sidelobe level is below -24 dB in both E- and H-plane. The highest gain is 34.5 dBi with 50% efficiency which is only 15% lower than that for uniform aperture illumination.

Solutions based on error-correcting codes for the blacklisting problem of a broadcast distribution system have been proposed by Kumar, Rajagopalan and Sahai. In this paper, detailed analysis of the solutions is presented. By choosing parameters properly in their constructions, we show that the performance is improved significantly.

This paper proposes a hardware configuration using only single pole dual throw (SPDT) switches to realize the previously proposed automatic calibration method using transmitting signals (ACT) for the adaptive array in TDD communication systems. The proposed configuration obtains the same calibration values as the conventional ACT does while reducing the number of switch branches. The transmission pattern using the proposed calibration method is also presented based on an experimental adaptive array testbed in an actual microcell environment. The experimental results show that the ideal radiation pattern formation is achieved by employing the proposed calibration method in an environment with a moving terminal station and where arriving co-channel interference exists.

In this paper, we are concerned in obtaining multicast trees in packet-switched networks such as ATM nets, when there exist constraints on the packet (cell)-replication capabilities of the individual switching nodes. This problem can be formulated as the Steiner tree problem with degree bounds on the nodes, so we call it the Degree-Constrained Steiner Tree problem (DCST). Four heuristic algorithms are proposed: the first is a combined version of two well-known Steiner tree algorithms, heuristic Naive and the shortest path heuristic (SPH), and the second is a relaxation algorithm based on a mathematical formulation of the DCST, and the last two use a tree reconfiguration scheme based on the concept of 'logical link. ' We experimentally compare our algorithms with the previous ones in three respects; number of solved instances, objective value or tree cost, and computation time. The experimental results show that there are few instances unsolved by our algorithms, and the objective values are mostly within 5% of optimal. Computation times are also acceptable.

This paper introduces a switched-voltage delay cell with differential inputs. It can be used as a building block for a range of analogue functions such as voltage-to-frenquency converter, A/D converter, etc. Applications incorporating the delay cell are presented. The performances are verified by simulations on PSpice.

The European Commission, through RACE, ACTS and now the IST programmes, has funded numerous consortium based research projects addressing capacity enhancement by means of Smart or Adaptive Antenna Technology. In addition to capacity enhancement, these projects have also considered the additional operational benefits, such as multipath mitigation and range extension, that this technology can offer to wireless network deployments. This paper provides an overview of the results obtained from the test-bed and field trial evaluations conducted under the ACTS TSUNAMI project. Here, a test-bed facility was developed by the project partners in order to appraise the potential merits of a Smart antenna facet deployment at the base-station cell site of a DCS1800 network. Details of the test-bed hardware and adaptive control algorithms are given, as well as results from the user tracking, traffic bearer quality assessments and range extension experiments. These results help substantiate many of the claims put forward by the proponents of Smart antenna technology, as well as ranking the relative performance of the family of adaptive control algorithms evaluated here. Further, new research activities, which embody Smart Antenna Technology, now supported under IST funding are also introduced.

The efficiency-fractional bandwidth product (EB), which is expressed as a ratio of the radiation resistance to the absolute value of the input reactance of an antenna, is used as a performance criterion for small dielectric loaded monopole antennas (DLMAs). The dependence of the EB on the permittivity of the dielectric loading (i.e., the electrical volume) is experimentally and numerically investigated for the first time in antenna research. As a result, it is found that the EBs of the some DLMAs are enhanced over a bare monopole antenna and an EB characteristic curve has a maximum point. This result suggests the presence of the optimum electrical volume for the dielectric loading in order to obtain the best EB performance. A general reason for the existence of the peak value is also explained using a mathematical deduction. Finally the system EB, which is an efficiency-fractional bandwidth product of the DLMA with a practical matching circuit, is defined and its dependence on the relative permittivity is illustrated. Consequently, the existence of the peak value is also confirmed for the system EBs. In addition, it is demonstrated that the enhancement of the system EB is mainly due to the enhancement in the efficiency of the antenna system.

A polarization diversity planar inverted-F antenna (PIFA) on portable telephone in the practical use near the operator's body is investigated at 1,800 MHz under multipath urban environment. The antenna structure comprises a center-fed square patch with one permanent short-pin and two RF-switches on three corners. The RF-switches perform as the polarization branch switches for dominantly vertical polarization (VP) or dominantly horizontal polarization (HP) modes. The radiation efficiency of the polarization diversity PIFA is 58% and 53% for VP and HP modes, respectively, which is higher than the 52% efficiency of the reference λ/4 monopole antenna under the same condition. The mean effective gain (MEG) of VP and HP modes decrease with respect to the increasing cross-polarization power ratio (XPR). The correlation coefficient of two diversity branches is between 0.66 through all the possible XPR ranging from -10 dB to +10 dB. The diversity gain is computed from the MEG and correlation coefficient to determine the diversity antenna gain (DAG). The diversity gain, based on 10-3 BER for selective combining, is 7.5 dB over non-diversity reception. The DAG is -1.2+2.8 dBi which is approximately 4 dB lower than the case without human body. In other words, the presence of the human body degrades the communication performance by a half.

This paper proposes a novel bi-directional rod antenna comprising a narrow patch and parasitic elements for base station antennas of street microcell systems. It is shown that the parasitic elements improve the antenna efficiency of an ordinary bi-directional printed antenna and make it possible to form the antennas using conventional substrates. This paper also proposes a suitable configuration for the array and investigates radiation characteristics of the configuration. Finally, a prototype of the bi-directional rod antenna is presented and the effectiveness of the bi-directional antenna is evaluated.