This paper surveys two methods for designing numerically robust geometric algorithms. The first method is the exact-arithmetic method, in which numerical computations are done in sufficiently high precision so that all the topological judgements can be done correctly. This method is usually accompanied with lazy evaluation and symbolic perturbation in order to reduce the computational cost and the implementation cost. The second method is the topology-oriented method, in which the consistency of the topological structure is considered as higher-priority information than numerical computation, and thus inconsistency is avoided. Both of the methods are described with the implementation examples.

Signal conservation logic (SCL) is a model of logic for the physical world subject to the matter conservation law. This letter proves that replication, complementary replication, and computational universality called elemental universality are equivalent in SCL. Since intelligence has a close relation to computational universality, the presented theorem may mean that life under the matter conservation law eventually acquires some kind of intelligence.

Metallic pair lines transmitting high-frequency information signals above several tens MHz are often used without being twisted, as flat floor cable installed in buildings, ribbon-type cables installed in computer equipment, and traces in printed circuit boards. However, the conversion characteristics of untwisted unbalanced metallic pair lines connecting unbalanced circuits have not been investigated over a wide range of frequencies in the MHz region. First, we developed a method to estimate effective power conversion factors using a cascade connection of F matrices, where the unbalance in impedance and admittance of each pair line is distributed uniformly along the line. As a result some useful information was obtained about the balance-unbalance conversion characteristics of the effective power which can be used to suppress EMI phenomena in wiring, especially over several decades of high frequencies. Next, we attempted to apply the conversion characteristics of untwisted unbalanced pair lines obtained at frequencies below several MHz to techniques for searching for the return circuits of conductors installed in buildings. It was clarified experimentaly that the depth of the equivalent ground plane can be estimated by comparing the measured conversion values of TV feeder lines installed at the place being tested with reference values measured in advance on a copper plate .

A nonlinear multiple complex sinusoidal estimator (NMSE) is proposed, as an extended and improved version with system noise of the single sinusoidal estimator previously presented by the author, for extracting multiple complex sinusoids in white noise. This estimator is derived by applying an extended complex Kalman filter (ECKF) to a noisy multiple complex sinusoidal model with state-representation, where the model becomes a nonlinear stochastic system. Proof of the stability is given by using a structure of the state-space signal model and Lyapunov techniques. Also, computer simulations demonstrate the effectiveness of the NMSE from various points of view.

This paper deals with two-processor scheduling for general acyclic SWITCH-less program nets with random node firing times. First, we introduce a hybrid priority list L* that has been shown to generate optimal schedules for the acyclic SWITCH-less program nets with unity node firing times, of which AND-nodes possess at most single input edge. Then considering the factors of existence of the AND-nodes with two input edges as well as random node firing times, we extend L* to design a new dynamic priority list Ld and four static priority lists {Lsii=1,2,3,4}; and then combining Ld and Lsi (i=1,2,3,4) we propose four hybrid priority lists {L*ii=1,2,3,4}. Finally, we apply genetic algorithm to evaluate the schedules generated by the four lists through simulations on 400 program nets. Our simulation results show two of the four lists can generate reasonably good schedules.

Nonlinear dynamics of xn+1=λ {4xn (1-xn)}q is studied in this paper. Different from the logistic map (q=1), in the case of q

It is well known that the electromagnetic interference (EMI) radiated from industrial, scientific and medical (ISM) apparatus seriously degrades the performance of wireless communication systems. In this paper, an ISM-band wireless local area network (WLAN) which employs a direct sequence-spread spectrum (DS-SS) system is designed to be sufficiently robust and reliable to operate in the presence of this EMI. To satisfy this goal, a technique to suppress EMI in the DS-SS system using a multicode transmission and an EMI observation channel is proposed. In the study, the EMI radiated from switching-type microwave ovens (MWO interference) which are ISM apparatus is concerned, and for a tractable investigation, a statistical model to represent MWO interference based on experimental measurement results is employed. As well known that MWO interference exhibits a bursty impulsive characteristic in time, a technique to transmit multiple long spreading codes (multicode transmission) is introduced for the DS-SS system to overcome the burstness of the interference. Moreover, inspired by the broadband in frequency of MWO interference, a technique to estimate the channel MWO interference by means of observing its levels in an adjacent channel is proposed, and this technique is applied to construct a multicode DS-SS receiver which can suppress the channel MWO interference. An evaluation of the bit error rate performance of the proposed multicode DS-SS system is conducted by computer simulation, and the numerical results demonstrate that the proposed DS-SS system can operate effectively even in the presence of MWO interference.

Given N real weights w1, w2, . . . , wN stored in one-dimensional array, we consider the problem for finding an optimal interval I [1, N] under certain criteria. We shall review efficient algorithms developed for solving such problems under several optimality criteria. This problem can be naturally extended to two-dimensional case. Namely, given a NN two-dimensional array of N2 reals, the problem seeks to find a subregion of the array (e. g. , rectangular subarray R) that optimizes a certain objective function. We shall also review several algorithms for such problems. We shall also mention applications of these problems to region segmentation in image processing and to data mining.

A new phasor model of neural networks is proposed in which the state of each neuron possibly takes the value at the origin as well as on the unit circle. A stability property of equilibria is studied in association with the energy landscape. It is shown that a simple condition guarantees an equilibrium to be asymptotically stable.

In order to investigate the possibility of avatar communication using sign-language, in this paper, we develop a sign-language chatting system on the Internet using CG aniamtion techniques between Korea and Japan. We construct the system in server-client architecture, where images of Korean or Japanese sign-language are analyzed into a series of parameters for sign-language animation by server. We transmit the parameters, which are text data instead of images or their compression, to clients and regenerate the corresponding CG animation using the received data. The chatting system is implemented with Visual C++ 5.0 on Windows platforms. Experimental results show that the sign-language could be used as a communication means between avatars of different languages.

In this paper, an algorithm of the median-cut quantization (MCQ) is proposed. MCQ is the technique that reduces multi-valued samples to binary-valued ones by adaptively taking the median value as the threshold. In this work, the search process of the median value is derived from the quick-sort algorithm. The proposed algorithm searches the median value bit by bit, and samples are quantized during the search process. Firstly, the bit-serial procedure is shown, and then it is modified to the bit-parallel procedure. The extension to the multi-level quantization is also discussed. Since the proposed algorithm is based on bit operations, it is suitable for hardware implementation. Thus, its hardware architecture is also proposed. To verify the significance, for the application to the motion estimation, the performance is estimated from the synthesis result of the VHDL model.

The performance of TCP/IP over ATM over an asymmetric digital subscriber line (ADSL) was investigated. Because the bandwidth of an ADSL link can vary over time due to changes in the link's physical conditions, which degrades TCP performance, we performed simulations for various ATM traffic controls, including available bit rate (ABR) and generic flow control, used to handle variations in the ADSL bandwidth. This analysis showed that using an ABR control is effective under various traffic conditions. An ABR switch algorithm that can achieve good performance under any condition was investigated.

It is important to establish the technology to accommodate best effort TCP/IP traffic over wide area ATM networks. The UBR (Unspecified Bit Rate) service category is the most typical service category for the best effort traffic, especially in the LAN environment. On the other hand, the VBR (Variable Bit Rate) service category with SCD (Selective Cell Discard) option is considered as the service category which is appropriate for wide area networks due to its fairness and minimum guarantee of the cell transmission using not only PCR (Peak Cell Rate) but SCR (Sustainable Cell Rate) and MBS (Maximum Burst Size). However, there is no actual evaluation for such service. We have, therefore, performed the experimental studies on TCP/IP over VBR with SCD along with UBR and VBR without SCD by VC (Virtual Channel) level policing when each TCP connection is mapped to a different VC. Through these experiments, we measured the link utilization of the effective data and the fairness between each obtained TCP throughput during the congestion of the ATM switch. From the results of the link utilization, the value is over 95% under the various conditions. Therefore, even in the case of the cell losses due to SCD or buffer overflow in ATM switch congestion, average throughput is almost the same as the value which equals the trunk line speed divided by the number of the accommodated TCP connections. From the results of the fairness, VBR with SCD per VC is better than UBR and also obtains better TCP throughput than VBR without SCD. Furthermore, to confirm those characteristics more generally, we adopt the accommodated TCP connections not only with the same TCP send/receive socket buffer size but with different sizes. Finally, we discuss the effectiveness between VBR with SCD and the other service categories, such as UBR and ABR (Available Bit Rate) and GFR (Guaranteed Frame Rate), and conclude that VBR with SCD is one of the most suitable ATM service categories for accommodating best effort traffic.

We have studied the characteristic trade-offs in low power and low voltage MOSFETs from the viewpoint of back-gate control and body effect factor. Previously reported MOSFET structures are classified into four categories in terms of back-gate structures. It is shown that a MOSFET with a fixed back-bias has only a limited current drive at low voltage irrespective of device structures, while current drive of a dynamic threshold MOSFET with body tied to gate is more enhanced with increasing body effect factor. We have proposed a new dynamic threshold MOSFET, electrically induced body (EIB) DTMOS, which has a very large body effect factor at low threshold voltage and high current drive at low supply voltage.

Heartbeat interval time series is an example of natural signals with 1/f characteristics. The exponent α of the 1/fα spectrum has some clinical significance. But sometimes the 1/f components is superimposed by some sinusoid components in the signal. To estimate the slope accurately, the 1/f component must be extracted from the signal. The singular spectrum analysis (SSA) method is recruited here to perform the task. Experimental results on data from real patients are satisfactory.

A large number of techniques have been proposed for acceleration of the Hough Transform, because the transformation is computationally very expensive in general. It is known that the sampling interval in parameter space is strongly related to the computation cost. The precision of the transformation and the processing speed are in a trade-off relationship. No fair comparison of the processing speed between various methods was performed in all previous works, because no criterion had been given for the sampling interval of parameter, and because the precision of parameter was not equal between methods. At the beginning of our research, we derive the relationship between the sampling interval and the precision of parameter. Then we derive a framework for comparing computation cost under equal condition for precision of parameter, regarding the total number of sampling points of a parameter as the computation cost. We define the transformation error in the Hough Transform, and the error is regarded as transformation noise. In this paper we also propose a design method called "Noise-level Shaping," by which we can set the transformation noise to an arbitrarily level. The level of the noise is varied according to the value of a parameter. Noise-level Shaping makes it possible for us to find the efficient parameterization and to find the efficient sampling interval in a specific application of the Hough Transform.

A multi-server system with trunk reservation is studied. The system is offered by two types of customers (class-1 and class-2). They arrive in independent batch Poisson streams and have an exponentially distributed service time. Class-1 customers will be lost or rejected if they find all S servers busy on their arrivals. Class-2 customers will use at most S'=S-R servers and enter a queue with N capacity if they find the number of idle servers less than or equal to R on their arrivals. Here, R is the number of reserved servers for class-1 customers. An example of the system is realized in NTT's facsimile communications network F-NET.

This paper addresses output regulation for nonlinear systems driven by a time varying parameter. The derivative information of the time varying parameter is necessary for the improved regulation performance but it is not readily available in general. In this paper, we propose a velocity estimation of the time varying parameter for use in the control law without amplifying noise signals.

The noise level distribution owing to only a non-stationary working objective machine has been stochastically expressed by reflecting the temporal change of distribution parameters under a generalized regression model especially with aid of the vibration level observation. The proposed method has been applied to a noise evaluation of non-stationarily operated jigsaw.

This paper presents a new fuzzy dynamic output feedback controller design technique for the Takagi Sugeno (T-S) fuzzy model with unknown-but-bounded time-varying modeling error. It is shown that the quadratic stabilization problem of the T-S fuzzy modeled system can be converted into an H control problem of the scaled polytopic Linear Parameter Varying (LPV) system. Then, a controller satisfying a prescribed H performance is designed for the stabilization of the T-S fuzzy modeled system.