The traceability of data flow diagrams against structure charts is very important for large software development. Specifying if there is a relationship between a data flow diagram and a structure chart is a time consuming task. Existing CASE tools provide a way to maintain traceability. If we can extract the input-output relationship of a system from a structure chart, the corresponding data flow diagram can be automatically generated from the relationship. For example, Benedusi et al. proposed a reverse engineering methodology to reconstruct a data flow diagram from existing code. The methodology develops a hierarchical data flow diagram from dependency relationships between the program variables. The methodology, however, transforms each module in structure charts into a process in data flow diagrams. The reconstructed diagrams may have different processes with the same name. This paper proposes a transformation algorithm that solves these problems. It analyzes the structure charts and extracts the input and ouput relationships, then determines how the set of outputs depends on the set of inputs for the data flow diagram process. After that, it produces a data flow diagram based on the include operation between the sets of output items. The major characteristics of the algorithm are that it is simple, because it only uses the basic operations of sets, it generates data flow diagrams with deterministic steps, and it can generate minimal data flow diagrams. This process will reduce the cost of traceability between data flow diagrams and structure charts.

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.

This paper proposes a human interface where a novel input method is used to substitute conventional input devices. It overcomes the deficiencies of physical devices, as it is based on image processing techniques. The proposed interface is composed of three parts: extraction of a person's handshape from a digitized image, detection of its fingertip, and interpretation by a software application. First, images of a pointing hand are digitized to obtain a sequence of monochrome frames. In each frame the hand is isolated from the background by means of gray-level slicing; with threshold values calculated dynamically by the combination of movement detection and histogram analysis. The advantage of this approach is that the system adapts itself to any user and compensates any changes in the illumination, while in conventional methods the threshold values are previously defined or markers have to be attached to the hand in order to give reference points. Second, once the hand is isolated, fingertip coordinates are extracted by scanning the image. Third, the coordinates are inputted to an application interface. Overall, as the algorithms are simple and only monochrome images are used, the amount of processing is kept low, making this system suitable to real-time processing without needing expensive hardware.

The impact of finite intermediate frequency (IF) on the sensitivity of heterodyne ASK lightwave receivers is examined and quantified. It is shown that certain choices of IF (fIFT=αopt, 3αopt/2, 2αopt, etc.) yield the same performance as infinite fIF where αopt is the optimum IF filter bandwidth when fIF=. The approximate results presented in this paper are within 0.4dB of exact results.

The distributed measurement-based quasi-fixed frequency assignment (also known as quasi-static adaptive frequency assignment-QSAFA) methodology is a practical solution for frequency assignment in the emerging TDMA personal communications networks (PCN/PCS). Five different QSAFA algorithms are studied in this paper under different interference threshold settings. It is found that a simple aggressive algorithm without using a threshold (LIA-Least Interference Algorithm) performs the best under the conditions studied. The performance of this algorithm is also justified by the theoretical proof presented at the end of this paper.

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.

Future digital land mobile communication, for a moving picture, requires more transmission speed and less bit error rate than the existing system does for speech. In the system, the intersymbol interference may not be ignored, because of higher transmission speed. An adaptive equalizer is necessary to cancel intersymbol interference. To achieve low bit error rate performance on the mobile radio channel, trellis-coded modulation with interleaving is necessary. This paper proposes an interleaved trellis-coded modulation scheme combined with a decision feedback type adaptive equalizer of high performance. The reliable symbol reconstructed in the trellis decoder is used as the feedback signal. To make equalizer be free from decoding delay, deinterleaving is effectively utilized. The branch metric, for trellis-coded modulation decoding, is calculated as terms of squared errors between a received signal and an expected signal by taking the reconstructed symbol and the impulse response estimated by the recursive least squares algorithm into account. The metric is constructed to have good discrimination performance to incorrect symbols even in non-minimum phase and to realize path diversity effect in a frequency selective fading channel. Computer simulation results are shown for several channel models. On a frequency selective fading channel, average bit error rate is less than 1/100 of that of the RLS-MLSE equalizer for fdTs=1/1000 at average Eb/N0 beyond 15dB. Performance degradation due to equalization error is less than 1.8dB. Performance is greatly improved by the effect of the reconstructed symbol feedback.

Closed-form solutions of the characteristic initial value problem for electric and magnetic fields propagating as nonsinusoidal plane TEM-waves in lossy unbounded media are calculated with Riemann's method and discussed in detail. As an application, the reflection and transmission of waves on a planar boundary is examined, when one semi-infinite medium is lossy.

A deterministic pushdown automaton (dpda) having just one stack symbol is called a deterministic restricted one-counter automaton (droca). A deterministic one-counter automaton (doca) is a dpda having only one stack symbol, with the exception of a bottom-of-stack marker. The class of languages accepted by droca's which accept by final state is a proper subclass of the class of languages accepted by doca's. Valiant has proved the decidability of the equivalence problem for doca's and the undecidability of the inclusion problem for doca's. Hence the decidability of the equivalence problem for droca's is obvious. In this paper, we evaluate the upper bound of the length of the shortest input string (witness) that disproves the inclusion for a pair of real-time droca's which accept by final state, and present a new direct branching algorithm for checking the inclusion for a pair of languages accepted by these droca's. Then we show that the worst-case time complexity of our algorithm is polynomial in the size of these droca's.

An error correction/detection decoding scheme of binary Hamming codes is proposed. Error correction is performed by algebraic decoding and then error detection is performed by simple likelihood ratio testing. The proposed scheme reduces the probability of undetected decoding error in comparison with conventional error correction scheme and increases throughjput in comparison with conventional error detection scheme.

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.

This paper presents a comprehensive framework for the organization, retrieval, and adaptation of image information and meta-information in image database systems. The multi-level hierarchy of images that emphasizes the composition of visual entities (such as Human, Chair, , etc.) from its constituents (eye, leg, , etc.) is managed by a host architecture that is called the semantic tree. This architecture is shown to integrate description, numeric, and statistic image constituent's information into a compound space that is used as retrieval basis for semantic, sketch, and template image queries and several other composite query types. The core architecture based on which the semantic tree is constructed is shown to offer several new features such as simple prototyping, complex prototyping, low storage requirements, and automatic knowledge acquisition compatibility. The object oriented data model constitutes our comparison basis throughout the paper. Methods (functions) used to access image information are shown to be organized into a separate architecture called the query dictionary. This architecture is shown to offer a convenient hierarchical message passing medium using which a variety of composite queries are constructed. Interaction between semantic trees and the query dictionary is clarified through several examples. It is shown that the semantic tree architecture embraces additional networking semantic intormation through a range of relation representation models, the first of which is introduced in this paper. A new inheritance method called semantic relation spreading is introduced. Comprehensive examples are given to demonstrate the versatility of the new strategy.

We have designed and implemented a simple yet powerful declarative synchronization mechanism for a paralle object-oriented computation model. The mechanism allows the user to control multiple message reception, specify the order of message reception, lock an invocation, and specify relations as invocation constraints. It has been included in a parallel object-oriented language, called A-NETL. The compiler and operating system have been developed on a total architecture, A-NET (Actors NETwork). The experimental results show that (i) the mechanism allows the user to model asynchronous events naturally, without losing the integrity of described programs; (ii) the replacement of the mechanism with the user's code requires tedious descriptions, but gains little performance enhancement, and certainly loses program readability and integrity; (iii) the mechanism allows the user to shift synchronous programs to asynchronous ones, with a scalable reduction of execution times: an average 20.6% for 6 to 17 objects and 46.1% for 65 objects. These prove the effectiveness of the proposed synchronization mechanism.

This paper describes a spatial and temporal multipath channel model which is useful in array antenna environments for mobile radio communications. From this model, a no distortion criterion, that is an extension of the Nyquist criterion, is derived for equalization in both spatial and temporal domains. An adaptive tapped-delay-line (TDL) array antenna is used as a tool for equalization in both spatial and temporal domains. Several criterion for such spatial and temporal equalization such as ZF (Zero Forcing) and MSE (Mean Square Error), are available to update the weights and tap coefficients. In this paper, we discuss the optimum weights based on the ZF criterion in both spatial and temporal domains. Since the ZF criterion satisfies the Nyquist criterion in case of noise free, this paper applies the ZF criterion for the spatial and temporal equalization as a simple case. The Z transform is applied to represent the spatial and temporal model of the multipath channel and to derive the optimal weights of the TDL array antenna. However, in some cases the optimal antenna weights cannot be decided uniquely. Therefore, the effect on the equalization errors due to a finite number of antenna elements and tap coefficients can be shown numerically by computer simulations.

This paper proposes a novel architecture and MMICs for an integrated 2-32 GHz front-end of a spectrum analyzer. The architecture achieves miniaturization by eliminating the large YIG tracking filter and also achieves multi-octave measurement with less than one octave sweep of the first local oscillator. The MMIC's demonstrate ultra-wideband performances with reduced chip sizes by utilizing newly developed FET cells for power combination, multi-order frequency conversion, low leakage variable resistance, and active impedance translation. The MMIC's are a fundamental/harmonic frequency converter, a variable attenuator, a single-pole triple-throw switch, a single-pole double-throw switch, a distributed pre-amplifier, and an active LC lowpass filter. All the MMIC's are smaller than 1 mm2, except the pre-amplifier and the filter.

In this letter, we introduce a predictor based least square (PLS) algorithm. By involving both order- and time-update recursions, the PLS algorithm is found to have a more stable performance compared with the stable version (Version II) of the RLS algorithm shown in Ref.[1]. Nevertheless, the computational requirement is about 50% of that of the RLS algorithm. As an application, the PLS algorithm can be applied to the fast Newton transversal filters (FNTF). The FNTF algorithms suffer from the numerical instability problem if the quantities used for extending the gain vector are computed by using the fast RLS algorithms. By combing the PLS and the FNTF algorithms, we obtain a much more stable performance and a simple algorithm formulation.

This paper presents a theoretically best algorithm within the framework of our image noise model for reconstructing 3-D from two views when all the feature points are on a planar surface. Pointing out that statistical bias is introduced if the least-squares scheme is used in the presence of image noise, we propose a scheme called renormalization, which automatically removes statistical bias. We also present an optimal correction scheme for canceling the effect of image noise in individual feature points. Finally, we show numerical simulation and confirm the effectiveness of our method.

This paper presents a simple and efficient method for estimation of parameters useful for textured image analysis. On the basia of a 2-D Wold-like decomposition of homogenenous random fields, the texture field can be decomposed into a sum of two mutually orthogonal components: a deterministic component and an indeterministic component. The spectral density function (SDF) of the former is a sum of 1-D or 2-D delta functions. The 2-D autocorrelation function (ACF) of the latter is fitted to the assumed anisotropic ACF that has an elliptical contour. The parameters representing the ellipse and those representing the delta functions can be used to detect rotation angles and scaling factors of test textures. Specially, rotation and scaling invariant parameters, which are applicable to the classification of rotated and scaled textured images, can be estimated by combining these parameters. That is, a test texture can be correctly classified even if it is rotated and scaled. Several computer experiments on natural textures show the effectiveness of this method.

This paper proposes a modified normalized LMS algorithm based on a long-term average of the reference input signal power. The reference input signal power for normalization is estimated by using two leaky integrators with a short and a long time constants. Computer simulation results compare the performance of the proposed algorithm with some previosuly proposed adaptive-step algorithms. The proposed algorithm converges faster than the conventional adaptive-step algorithms. Almost 30dB of the ERLE (Echo Return Loss Enhancement), which is comparable to the conventional algorithms, is achieved in noisy environments.

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.