We propose a learning algorithm for self-organizing neural networks to form a topology preserving map from an input manifold whose topology may dynamically change. Experimental results show that the network using the proposed algorithm can rapidly adjust itself to represent the topology of nonstationary input distributions.

In this paper 2-10 GHz hybrid-distributed preamplifiers using two and three cascaded single stage distributed amplifiers are demonstrated. These amplifiers produce available power gains significantly higher than conventional distributed preamplifiers using the same number of active devices. Simulation results show the advantage of the proposed preamplifier over the conventional one. Measured results of the two realised configurations of preamplifiers using two and three cascaded single stage distributed amplifiers are presented. Each configuration shows that the available power gain can be increased by increasing interstage characteristic impedance of the cascaded single stage distributed amplifiers. The measured available power gain for two stages shows an improvement from 18 dB to 20 dB, and for three stages an improvement from 26 dB to 31 dB across the 2-10 GHz frequency band, as the inter-stage characteristic impedance is increased from low to high level. Input and output return losses better than -10 dB, and input-output isolation better than -55 dB at the beginning of the band and better than -45 dB at the end are achieved. This approach also provides a good measured noise figure performance of an average of 4 dB across the 2-10 GHz frequency band for both two and three cascaded stages. The group delay of both cascaded amplifiers are measured. Its flat performance proves the viability of this approach which is suitable for digital optical communication and pulse applications.

This paper describes an MOS current-mode, voltage-controlled oscillator (VCO) circuit that potentially operates with a 2 V supply voltage, 500 MHz oscillation frequency, and -90 dBc/Hz phase noise at the 1 MHz offset. It also has an improved oscillation frequency linearity of the control voltage and 11 mW power dissipation. The oscillation frequency reached 920 MHz when the supply voltage was increased to 3 V.

In order to investigate the dynamic behavior of quantized interconnection neural networks on neuro-chips, we have designed and fabricated hardware neural networks according to design rule of a 1.2 µm CMOS technology. To this end, we have developed programmable synaptic weights for the interconnection with three values of 1 and 0. We have tested the chip and verified the dynamic behavior of the networks in a circuit level. As a result of our study, we can provide the most straightforward application of networks for a dynamic pattern classifier. The proposed network is advantageous in that it does not need extra exemplar to classify shifted or reversed patterns.

The transfer function of IIR all-pass filters is a rational function of ω. However, the optimization of such a rational function using the successive projections method, which has a wider range of application than the Remez algorithm, has not been presented. In this paper, we propose designing IIR all-pass filters using the successive projections method.

A new practical coherent detection scheme for biorthogonal signals, which uses multi-symbol observation interval, is proposed and its performances are analyzed and simulated. The technique jointly estimates both the demodulated data and the channel from received signal only while reducing computation complexity by an approximate maximum-likelihood sequence estimation rather than symbol-by-symbol detection as in previous noncoherent detection. The scheme achieves performance close to that of ideal coherent detection with perfect channel estimates when select the appropriate observation symbol interval N in the given symbol alphabet size M. What is particularly interesting is that the required average signal-to-noise ratio per bit γb can be reduced by as much as 1.4 dB and the capacity can be increased by as much as 38% when we use this system in the CDMA cellular reverse link.

According to the wide spread of mobile computer terminals, it is required to connect them to remote networks and to allow them to communicate with home computers and Internet servers. There are some mechanisms studied on the IP terminal mobility, including DHCP which assigns IP addresses dynamically and Mobile-IP which supports seemless mobility. However, there are some problems identified for those methods on compatibility with existing IP terminals, route optimization and compatibility with firewall systems. So we have proposed a virtual subnetwork system which can accommodate existing IP routers and terminals without any modifications, and which selects an optimal route for the communication with networks other than the home network. This paper describes the mechanism and the results of implementation of our system.

In a multisystem data sharing environment (MDSE), the computing nodes are locally coupled via a high-speed network and share a common database at the disk level. To reduce the amount of expensive and slow disk I/O, each node caches database pages in its main memory buffer. This paper focuses on the MDSE that uses record-level locking as a concurrency control. While the record-level locking can guarantee higher concurrency than page-level locking, it may result in heavy message traffic. In this paper, we first propose a cache coherency scheme that can reduce the message traffic in the standard locking. Then the scheme is extended to the context where lock caching and lock de-escalation are adopted. Using a distributed database simulation model, we evaluate the performance of the proposed schemes under a wide variety of database workloads.

In this paper, we propose a new adaptive control system design using internal model principle (IMP) for a bounded polynomial parameters. In this method, we regard time varying parameters as variable disturbance and design an estimating law used the internal model of the disturbance so that the law is able to rejected the effectness of the disturbance. Our method has the features that the tracking error can converge to zero. Furthermore, we give a sufficient condition for the stability based on a small-gain theorem. The condition shows that our proposed method relax the stability condition more than the conventional methods based on a passivity theorem. Finally, we contain a numerical simulation to show an effect of our system.

We have developed a practical 3-D integrated process simulator (3-D MIPS) based on the orthogonal grid. 3-D MIPS has a 3-D topography simulator (3-D MULSS) and 3-D impurity simulator which simulates the processes of ion implantation, impurity diffusion and oxidation. In particular, its diffusion and segregation model is new and practical. It assumes the continuity of impurity concentration at the material boundary in order to coordinate with the topography simulator (3-D MULSS) with cells in which two or more kinds of materials exist. And then, we introduced a time-step control method using the Dufort-Frankel method of diffusion analysis for stable calculation, and a selective oxidation model to apply to more general structures than LOCOS structure. After that, the 3-D MIPS diffusion model is evaluated compared with experimental data. Finally, the 3-D MIPS is applied to 3-D simulations of the nMOS Tr. structure with LOCOS isolation, wiring interconnect and pn-junction capacitances, and DRAM storage node area.

Fluctuations of three device parameters (Tox, Nsub, ΔL) based on process fluctuations are taken as cause of device/circuit performances. In-line measured device parameters are approximated by Gaussian functions, and their 2σ values are assigned as boundaries of the performance fluctuations. Measured distributions both for device and curcuit performances are successfully reproduced.

This paper develops a deterministic model for evaluating the influence of building windows upon the outdoor-to-indoor propagation path in cellular systems. This prediction model is based on the Aperture-field method of Huygens-Fresnel wave theory. Penetration losses and indoor signal characteristics are analyzed. It is found that the window frames of the building play an important role in determining the indoor field intensities. In order to verify this model's accuracy, numerical results are compared with measurement values. The calculations agree well with the measurements.

After a brief discussion of the demands in meshing for semiconductor process and device simulation, we present a three-dimensional Delaunay refinement technique combined with a modified advancing front algorithm.

A new IC interconnect transmission line parameter determination methodology and a novel fast simulation technique for non-uniform transmission lines are presented and verified. The capacitance parameter is a strong function of a shielding effect between the layers, while silicon substrate has a substantial effect on inductance parameter. Thus, they are taken into account to determine the parameters. Then the virtual straight-line-based per unit length parameters are determined in order to perform the fast transient simulation of the non-uniform transmission lines. It was shown that not only the inductance effect due to a silicon substrate but also the shielding effect between the layers are too significant to be neglected. Further, a model order reduction technique is integrated into Berkeley SPICE in order to demonstrate that the virtual straight-line-based per-unit-length parameters can be efficiently employed for the fast transient response simulation of the complicated multi-layer interconnect structures. Since the methodology is very efficient as well as accurate, it can be usefully employed for IC CAD tools of high-performance VLSI circuit design.

In this paper, a clustering-based method is proposed for automatically constructing a multi-input Takagi-Sugeno (TS) fuzzy model where only the input-output data of the identified system are available. The TS fuzzy model is automatically generated by the process of structure identification and parameter identification. In the structure identification step, a clustering method is proposed to provide a systematic procedure to partition the input space so that the number of fuzzy rules and the shapes of fuzzy sets in the premise part are determined from the given input-output data. In the parameter identification step, the recursive least-squares algorithm is applied to choose the parameter values in the consequent part from the given input-output data. Finally, two examples are used to illustrate the effectiveness of the proposed method.

This paper considers the problem of generating various calligraphy from some sample fonts. Our method is based on the deformable contour model g-snake. By representing the outline of each stroke of a character with a g-snake, we cast the generation problem into global and local deformation of g-snake under different control parameters, where the local deformation obeys the energy minimization principle of regularization technique. The base values of the control parameters are learned from given sample fonts. The experimental results on alphabet and Japanese characters Hiragana show such processing as a reasonable method for generating calligraphy.

A distributed computing system consists of processing elements, communication links, memory units, data files, and programs. These resources are interconnected via a communication network and controlled by a distributed operating system. The distributed program reliability (DPR) in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to retrieve data files from other processing elements will be executed successfully. This reliability varies according to 1) the topology of the distributed computing system, 2) the reliability of the communication edges, 3) the data files and programs distribution among processing elements, and 4) the data files required to execute a program. In this paper, we show that computing the distributed program reliability on a star distributed computing system is #P-complete. A polynomially solvable case is developed for computing the distributed program reliability when some additional file distribution is restricted on the star topology. We also propose a polynomial time algorithm for computing the distributed program reliability with approximate solutions when the star topology has no the additional file distribution.

In this paper, we propose methods for testing the usability of graphical user interface (GUI) applications based on log files of user interactions. Log analysis by existing methods is not efficient because evaluators analyze a single log file or log files of the same user and then manually compare results. The methods proposed here solve this problem; the methods enable evaluators to analyze the log files of multiple users together by detecting interaction patterns that commonly appear in the log files. To achieve the methods, we first clarify usability attributes that can be evaluated by a log-based usability testing method and user interaction patterns that have to be detected for the evaluation. Based on an investigation on the information that can be obtained from the log files, we extract the attributes of clarity, safety, simplicity, and continuity. For the evaluations of clarity and safety, the interaction patterns that have to be detected include those from user errors. We then propose our methods for detecting interaction patterns from the log files of multiple users. Patterns that commonly appear in the log files are detected by utilizing a repeating pattern detection algorithm. By regarding an operation sequence recorded in a log file as a string and concatenating strings, common patterns are able to be detected as repeating patterns in the concatenated string. We next describe the implementation of the methods in a computer tool for log-based usability testing. The tool, GUITESTER, records user-application interactions into log files, generates usability analysis data from the log files by applying the proposed methods, and visualizes the generated usability analysis data. To show the effectiveness of GUITESTER in finding usability problems, we report an example of a usability test. In this test, evaluators could find 14 problems in a tested GUI application. We finally discuss the ability of the proposed methods in terms of its log analysis efficiency, by comparing the analysis/sequence time (AT/ST) ratio of GUITESTER with those of other methods and tools. The ratio of GUITESTER is found to be smaller. This indicates the methods make log analysis more efficient.

We have improved the mechanical reliability of deep-submicron semiconductor devices by applying a simulation technique. Typical kinds of damages that reduce the reliability are dislocations in silicon substrates, delamination or cracking of thin films, and deterioration of electronic characteristics of devices. The mechanical stress that develops in device structures is caused by not only mismatches in thermal expansion coefficients among thin film materials but also intrinsic stress of thin films such as poly-silicon and silicides. Fine patterning by dry etching makes sharp edges and they also cause stress concentration and thus high stress. The manufacturing processes in which stress mainly develops are isolation, gate formation, and interconnect formation. We have developed methods for reducing the stress in each of the above-mentioned process. This stress reduction is very effective for highly reliable manufacturing. Finally, we clarify the effect of the residual stress in transistor structures on shift in the electronic characteristics of MOS transistors.

To design and develop user-oriented, flexible and distributed applications which can deal with various users' requirements, new technologies to manage, control and utilize the services of communication networks have to be provided. In this paper, the current challenges faced by large-scale distributed applications are discussed and a framework for the next generation network operation and management is presented on the basis of agent-based computing technologies. Examples of flexible distributed applications are presented to clarify the role of application-centric flexible network operation and management.