This paper proposes a technique for estimating the harmonic frequencies based on instantaneous frequency (IF) of speech signals. The main problem is how to decompose the speech signal into the harmonic components. For this purpose, we use a set of bandpass-filters, each of whose center frequencies changes with time in order to track the instantaneous freuency of its output. As a result, the outputs of the band-pass filters become the harmonic components, and the instantaneous frequencies of the harmonics are accurately estimated. To evaluate the effectiveness of the approach, we apply it to pitch determination of speech. Pitch determination is simply accomplished by selecting the correct fundamental frequency out of the harmonic components. It is confirmed that the pitch extraction using the proposed pitch determination algorithm (PDA) is stable and accurate. The most significant feature of the PDA is that the extracted pitch contour is smooth and it requires no post-processing such as nonlinear filtering or any smoothing processes. Several examples are presented to demonstrate the capability of the harmonics estimation technique and the PDA.

The background concepts and methodologies of the knowledge-based program understander ALPUS is discussed. ALPUS understands user's buggy Pascal programs using four kinds of programming knowledge: the knowledge on algorithms, programming techniques, the Pascal language, and logical bugs. The knowledge on algorithms, the key knowledge, is represented in a form of hierarchical data structure called Hierarchical Procedure Graph (HPG). In HPG each node represents a chunk of operations called process," which is consisted of sub-processes. The other knowledge is maintained as independent knowledge bases and linked to associated processes of the HPG. The knowledge about bugs acquired by cognitive experiment is grouped into three categories: bugs on algorithms, programming techniques, and the Pascal language, and connected to associated elements of programming knowledge respectively. ALPUS tries to understand user's buggy programs, detects logical bugs, infers user's intentions, and gives advices for fixing bugs. Program understanding is achieved by three steps: normalization, variable identification, and process and technique identification. Normalization results in improving flexibility of understanding. Variable, process and technique identifications are achieved by knowledge-based pattern matching. Intentions are inferred by means of information attached to buggy patterns. The result of comprehension is reported to a user (i.e., student). Experimental results using Quicksort programs written by students show that the HPG formalism is quite powerful in understanding algorithm-oriented programs. The ALPUS's way of program comprehension is useful in the situation of programming education in an intermediate class of an engineering school. The ALPUS system is a subsystem of the intelligent programming environment INTELLITUTOR for learning programming, which was implemented in the frame-based knowledge engineering environment ZERO on a UNIX workstation.

This paper describes, from a system architectural viewpoint, how knowledge-based technologies have been utilized in developing EXLOG (an LSI circuit synthesis system) and SOFTEX (a software synthesis system) inside the authors' projects. Although the system architectures for EXLOG and SOFTEX started from the same production systems, consisting of transformation rules in the middle of the 1980's, both branched off in different directions in the 1990's. Based on experiences with EXLOG and SOFTEX, the differences between LSI and software design models are discussed, and the future directions are indicated for the knowledge-based design system architectures.

This paper discusses crystal-growth and device-design issues associated with the development of high-performance InP/InGaAs heretostructure bipolar transistors (HBTs). It is shown that a highly Si-doped n+-subcollector in the HBT structure causes anomalous Zn redistribution during metalorganic vapor phase epitaxial (MOVPE) growth. A thermodynamical model of and a useful solution to this big problem are presented. A novel hybrid structure consisting of an abrupt emitter-base heterojunction and a compositionally-graded base is shown to enhance nonequilibrium base transport and thereby increase current gain and cutoff frequency fT. A double-heterostructure bipolar transistor (DHBT) with a step-graded InGaAsP collector can improve collector breakdown behavior without any speed penalty. We also elucidate the effect of emitter size shrinkage on high-frequency performance. Maximum oscillation frequency fmax in excess of 250 GHz is reported.

This paper proposes a requirement description and elicitation approach for communication services. Requirements are described in natural language, refined with a knowledge base, and converted to a formal language for program generation. A model for communication services is made as a set of three items: terminal state, terminal action and the response of the communication system to the action. This set, in turn, corresponds to natural language syntax that expresses two conditions (terminal state and action) and their result. These conditions and result are expressed as a sequence of simple sentences that describe the relationship between a terminal and a communication system. Thus, by defining such a description style to reflect the features of communication services, it should be possible to achieve both a high level of description and mechanical processing capabilities at the same time. However, requirement descriptions usually include omission and inconsistency. This problem cannot be solved by merely introducing natural language for the descriptions. Knowledge about the target domain of requirements is needed to resolve it. This paper reports on a knowledge base that stores constraints existing between conditions and results in communication services. This knowledge base is shown to be effective in supplementing omissions and resolving inconsistency. This paper also presents a technique for converting the elicited requirements in natural language to descriptions in a formal language that can be used to generate a program.

A bottleneck identification methodology is proposed for the performance-oriented design of shared-bus multiprocessors, which are composed of several major subsystems (e.g. off-chip cache, bus, memory, I/O). A subsystem with the longest access time per instruction is the one that limits processor performance and creates a bottleneck to the system. The methodology also facilitates further refined analysis on the access time of the bottleneck subsystem to help identify the causes of the bottleneck. Example performance model of a particular shared-bus multiprocessor architecture with separate address bus and data bus is developed to illustrate the key idea of the bottleneck identification methodology. Accessing conflicts in subsystems and DMA transfers are also considered in the model.

Spectrum scrambling can be applied in vehicle telephones for more secure communication. This letter shows a spectrum scrambling method using real coefficients M band uniform QMF banks. Once QMF banks are designed, spectrum scrambling filters can be realized with simpler procedures. By introducing selectors in the filters, the scrambling scheme may be easily varied in real time processing. Design examples and experimental simulations are included.

In this paper, a novel noise parameters extraction technique for microwave packaged BJT and FET is proposed. The noise parameters of packaged BJT and FET for the entire operating frequency band can be obtained from the four noise parameters measured at a single frequency or a few frequencies. The predicated results obtained with this method agree well with the measured data. As a result, the novel noise parameters extraction technique can be used to predict the noise with a minimum effort.

A transmission power control technique on a TDD-CDMA/TDMA system for wireless multimedia networks is proposed. The assumed network connects mobile terminals to a node of an ATM based high speed LAN through a radio central unit. Only human interface facilities are implemented into the terminal so that users access integrated services through the node of the network. The uplink (from a mobile terminal to a radio central unit) employs a CDMA scheme to transmit human interface signals (2.4kbit/s) and the downlink employs a TDMA scheme to transmit display interface signals (24 Mbit/s). Both the CDMA and the TDMA signals occupy the same frequency band. To mitigate bit error rate degradation due to the fading, the radio central unit estimates the impulse response of the channel from the received CDMA signals and controls the transmission power of the TDMA signals to compensate the fading attenuation. The bit error rate performance of the downlink with the proposed transmission power control is theoretically analyzed under several fading conditions. Numerical results using the Nakagami-m fading model and recent propagation measurements show that the proposed power control technique compensates the fading attenuation and improves the bit error rate performances. The bit error rate of the downlink is reduced from 10-2 to 10-5 at the symbol SNR of 20dB by employing the proposed transmission power control, which is less sensitive to the severity of the fading. Furthermore, the proposed transmission power control is implemented without increasing the terminal complexity because all the processing on the power control of the downlink is carried out only in the radio central unit.

A novel method is presented for designing discrete coeffcient FIR linear phase filters using Hopfield neural networks. The proposed method is based on the minimization of the energy function of Hopfield neural networks. In the proposed method, the optimal solution for each filter gain factor is first searched for, then the optimal filter gain factor is selected. Therefore, a good solution in the specified criterion can be obtained. The feature of the proposed method is that it can be used to design FIR linear phase filters with different criterions simultaneously. A design example is presented to demonstrate The effectiveness of the proposed method.

A new variable step size Least Mean Square (LMS) FIR adaptive filter algorithm (VSS-CC) is proposed. In the VSS-CC algorithm the step size adjustment (α) is controlled by using the correlation between the output error (e(n)) and the adaptive filter output ((n)). At small times, e(n) and (n) are correlated which will cause a large α providing faster tracking. When the algorithm converges, the correlation will result in a small size α to yield smaller misadjustments. Computer simulations show that the proposed VSS-CC algori thm achieves a better Echo Return Loss Enhancemen (ERLE) than a conventional NLMS Algorithm. The VSS-CC algorithm was also compared with another variable step algorithm, achieving the VSS-CC a better ERLE when the additive noise is incremented.

This paper condiders a problem of logecal configuration in reconfigurable VCDN (Virtual Circuit Data Networks) which is analyzed through a mimimax approach, and its objective is to minimize the largest delay on any logical link, measured in both queueing delay and propagation delay. The problem is formulated as a 0/1 mixed integer programming and analyzed by decomposing it into two subproblems, called routing and dimensioning problems, for which an efficient hauristic algorithm is proposed in an iterating process made beween the two subproblems for solution improvement. The algorithm is tested for its performance eveluation.

This paper describes modifications to a previously proposed 8-kb/s 4-ms-delay CELP speech coding algorithm with a view to improving the speech quality while maintaining low delay and only moderately increasing complexity. The modifications are intended to improve the effectiveness of interframe pitch lag prediction and the sub-optimality level of the excitation coding to the backward adapted synthesis filter by using delayed decision and joint optimization techniques. Results of subjective listening tests using Japanese speech indicate that the coded speech quality is significantly superior to that of the 8-kb/s VSELP coder which has a 20-ms delay. A method that reduces the computational complexity of closed-loop 3-tap pitch prediction with no perceptible degradation in speech quality is proposed, based on representing the pitch-tap vector as the product of a scalar pitch gain and a normalized shape codevector.

This paper described discrete time Cellular Neural Networks (DT-CNN) with two types of neuron circuits for image coding from an analog format to a digital format and their VLSI implementations. The image coding methods proposed in this paper have been investigated for a purpose of transmission of a coded image and restoration again without a large loss of an original image information. Each neuron circuti of a network receives one pixel of an input image, and processes it with binary outputs data fed from neighboring neuron circuits. Parallel dynamics quantization methods have been adopted for image coding methods. They are performed in networks to decide an output binary value of each neuron circuit according to output values of neighboring neuron circuits. Delayed binary outputs of neuron circuits in a neighborhood are directly connected to inputs of a current active neuron circuit. Next state of a network is computed form a current state at some neuron circuits in any time interval. Models of two types of neuron circuits and networks are presented and simulated to confirm an ability of proposed methods. Also, physical layout designs of coding chips have been done to show their possibility of VLSI realizations.

This paper proposes a new type of optically controlled BFN (beam forming network), an electro-optic BFN using an optical waveguide structure. In this BFN, antenna beam forming is performed using conventional optical variable phase shifters and conventional optical variable directional couplers. An electro-optic BFN can easily utilize monolithic integration capability that will be advantageous to microwave stabilization. In order to discuss practical applicability, microwave characteristics and beam forming characteristics were examined using an experimental BFN fabricated on a LiNbO3 substrate. Resulting from electro-optic lightwave control, linear phase shifting and variable amplitude distribution were measured at various microwave frequencies. Without any other control except for optical offset frequency locking and applying constant voltages, typical short term fluctuation in L-band microwave was measured to be within 3 degreesp-p in phase and 2.5 dBp-p in amplitude, respectively. For the first time, an electro-optic BFN was successful in performing beam forming in an L-band array antenna as well as coaxial cables. It was also verified that radiation pattern measured in 60 degree beam steering using the experimental BFN was comparable to that calculated using conventional microwave BFNs. The experimental results show the feasibility of utilizing an electro-optic BFN in future advanced microwave/millimeter-wave array antenna systems.

This paper investigates the accepting powers of one-way alternatiog finite automata with counters and stack-counters (lafacs's) which operate in realtime. (The difference between counter" and stack-counter" is that the latter can be entered without the contents being changed, but the former cannot.) For each k0 and l0 ((k, l)(0, 0)), let 1AFACS(k, l, real) denote the class of sets accepted by realtime one-way alternating finite automata with k counters and l stack-counters, and let 1UFACS(k, l, real) (1NFACS(k, l, real)) denote the class of sets accepted by realtime one-way alternating finite automata with k counters and l stack-counters which have only universal (existential) states. We first investigate a relationship among the accepting powers of realtime lafacs's with only universal states, with only existential states, and with full alternation, and show, for example, that for each k0 and l0 ((k, l)(0, 0)), 1UFACS(k, l, real) 1NFACS(k, l, real) 1AFACS(k, l, real). We then investigate hierarchical properties based on the number of counters and stack-counters, and show, foe example, that for each k0 and l0 ((k, l)(0, 0)), and each X{U, N}, 1XFACS(k1, l, real)1AFACS(k, l, real)φ. We finally investigate a relationship between counters and stack-counters, and show, for example, that for each k0, l0 and m1, and each X{U, N}, 1XFACS(k, lm, real)1AFACS(k2m1, l, real)φ.

Data flow is a paradigm for concurrent computations in which a collection of parallel processes communicate asynchronously. For nondeterministic data flow networks many semantic models have been defined, however, it is complex to reason about the semantics of a network. In this paper, we introduce a transformation between data flow networks and the LOTOS specification language to make available theories and tools developed for process algebras for the semantic analysis based on traces of the networks. The transformation does not establish a one-to-one mapping between the traces of a data flow network and the LOTOS specification, but maps each network in a specification which usually contains more traces. The obtained system specification has the same set of traces as the corresponding network if they are finite, otherwise also non fair traces are included. Formal analysis and verification methods can still be applied to prove properties of the original data flow network, allowing in case of networks with finite traces to prove also network equivalence.

In this paper, we discuss design of quadrature mirror filter (QMF) banks using digital allpass networks in the frequency domain. In the QMF banks composed of a parallel connection of two allpass networks, both aliasing error and amplitude distortion are always completely canceled. Therefore, we only need to design the analysis filters and eliminate phase distortion of the overall transfer function. We consider design of the QMF banks in two cases where phase responses of the filters are repuired or not required. In the case where the phase responses are not required, the design problem can be reduced to design of phase difference of two allpass networks. In the case where the phase responses are required, we present a procedure for designing the QMF banks with both equiripple magnitude and phase responses.

Interdigital transducers (IDTs) with leaky-SAWs propagating on 36 YX-LiTaO3, and 41 and 64 YX-LiNbO3 were theoretically analyzed, providing a new equivalent circuit. This equivalent circuit included attenuation constant due to leakage as well as conductance caused by bulkwave radiation. All circuit parameters were derived by solving integral equations. Fundamental experiments showed fairly good agreement between theoretical and experimental results, which gave very accurate design tools for leaky-SAW devices.

This paper presents an analytical study and computer-based model of radio wave polarization propagating through a microcell. It covers the following topics: the influence of random orientation of a handset terminal on the performance of communication systems using either a linearly or circularly polarized base-station antenna; an analysis of the computer-based simulation of the power response on different polarizations in a street-canyon microcell.