We present an efficient scheme for progressive fractal coding in a wavelet multiresolution pyramid. In our proposed scheme, range blocks are selectively coded, based on energy localization in wavelet bands. In order to form domain pools with blocks yielding less distortion, domain blocks are also selectively searched in the wavelet bands of either the same or a different orientation from that of each range block at the next lower resolution. It is shown that the performance of the non-hybrid fractal coder presented is much better than that of predictive pyramid coding (PPC).

This paper proposes an operation-region model for analyzing and testing analog and mixed-signal circuits, which is based on observation of change in MOSFET operation regions. First, the relation between the change in MOSFET operation regions and the fault behavior of a mixed-signal circuit containing a bridging fault is investigated. Next, we propose an analysis procedure based on the operation-region model and apply it to generate the optimal input combination for testing the circuit. We also determine which transistors should be observed in order to estimate the circuit behavior. Since the operation-region model is a method for modeling circuit behavior abstractly, the proposed method will be useful for modeling circuit behavior and for analyzing and testing many kinds of analog and mixed-signal circuits.

Test compression/decompression is an efficient method for reducing the test application cost. In this paper we propose a test generation method for obtaining test-patterns suitable to test compression by statistical coding. In general, an ATPG generates a test-pattern that includes don't-care values. In our method, such don't-care values are specified based on an estimation of the final probability of 0/1 occurrence in the resultant test set. Experimental results show that our method can generate test patterns that are able to be highly compressed by statistical coding, in small computational time.

In this paper, a method is proposed to construct an n-out-of-n visual secret sharing scheme for gray-scale images, for short an (n,n)-VSS-GS scheme, which is optimal in the sense of contrast and pixel expansion, i.e., resolution. It is shown that any (n,n)-VSS-GS scheme can be constructed based on the so-called polynomial representation of basis matrices treated in [15],[16]. Furthermore, it is proved that such construction can attain the optimal (n,n)-VSS-GS scheme.

In this paper we propose two diagnosis methods for crosstalk-induced pulse faults in sequential circuits using crosstalk fault simulation. These methods compare observed responses and simulated values at primary outputs to identify a set of suspected faults that are consistent with the observed responses. The first method is a restart-based method which determines the suspected fault list by using the knowledge about the first and last failures of the test sequence. The advantage of the restart-based method over a method using full simulation is its reduction of the number of simulated faults in a process of diagnosing faults. The second method is a resumption-based method which uses stored state information. The advantage of the resumption-based method over the restart-based method is its reduction of the CPU time for diagnosing the faults. The effectiveness of the proposed methods is evaluated by experiments conducted on ISCAS '89 benchmark circuits. From the experimental results we show that the number of suspected faults obtained by our methods is sufficiently small, and the resumption-based method is substantially faster than the restart-based method.

This paper deals with formal verification of high-level designs, in particular, symbolic comparison of register-transfer-level descriptions and behavioral descriptions. We use state machines extended by quantifier-free first-order logic with equality, as models of those descriptions. We cannot adopt the classical notion of equivalence for state machines, because the signals in the corresponding outputs of such two descriptions do not change in the same way. This paper defines a new notion of consistency based on signal-transitions of the corresponding outputs, and proposes an algorithm for checking consistency of those descriptions, up to a limited number of steps from initial states. As an example of high-level designs, we take a simple hardware/software codesign. A C program for digital signal processing called PARCOR filter was compared with its corresponding design given as a register-transfer-level description, which is composed of a VLIW architecture and assembly code. Since this example terminates within approximately 4500 steps, symbolic exploration of a finite number of steps is sufficient to verify the descriptions. Our prototype verifier succeeded in the verification of this example in 31 minutes.

In conventional Web Geographic Information System (GIS), there are serious drawbacks of high waiting time and low accessibility because the subsequent query has to wait until all the spatial data has been completely transmitted. In addressing these problems, this paper proposes a progressive transmission method which can reduce waiting time and increase accessibility. The proposed method has the following steps. First, significant vertices of geographic objects are selected into based on an algorithm, Priority_Order_Estimation (POE). Second, the selected vertices are inserted the data structure, Priority_Order_Queue (POQ). This allows a client to view, to request and occasionally to reject spatial data, rather than waiting for the whole map to arrive. Third, the transmission steps are processed progressively, where significant vertices of POQ are sent from server to client one by one. In the final step, if necessary, the entire spatial data set of SENDOBJSP, which is a transmission structure, is transmitted so that the original map is accurately displayed. The performance of the system proposed here has been evaluated according to the factors such as system response time and client storage space. For the comparisons, the total transmission method, layer transmission method and the proposed four-step transmission method were used. Compared with the conventional Web-based GIS, the system response time is twenty-two percent shorter and client storage space is reduced by about twenty-one percent. As a result, performance improvement, fast response time and less client storage usage, is achieved. Therefore, the proposed method can make a significant contribution in support of Web-based Vector GIS applications such as Environmental Management, Map On Demand Service and Assessment and Planning System.

The present paper deals with the frequency-dependent finite difference time domain ((FD)2TD) method analysis of the light-beam scattering from a land/groove recording magneto-optical (MO) disk model with an Al reflective layer (ALRL) in order to improve the conventional analysis for MO disk models under the assumption of perfectly conducting reflective layer (PCRL). Numerical examples of main- and cross-polarized scattered fields and the phase difference between them are presented. We show the comparison of the scattering characteristics between ALRL and PCRL, and also examine the dependence of the cross talk of the readout signal due to adjacent recorded marks on both the recorded mark size and the depth of grooves.

The plan of High Altitude Platform Station (HAPS) is considered as a revolutionary wireless system plan with several economic and technological advantages over both space- or ground-based counterparts. In this paper, we propose a joint system of terrestrial and HAPS cellular for Wideband-CDMA mobile communication. This system makes the conventional terrestrial W-CDMA cellular area smaller and the remainder area covered by HAPS to increase the total capacity. Furthermore in down link channel, we introduce the polarized wave and doughnut-like radiation. However, in the proposed system, the performance would be dependent on the terminal position especially near the boundary of doughnut-like cell zone. To overcome this, site diversity that uses both signals from terrestrial Base Station and HAPS Base Station is also introduced. To confirm the availability of the proposed system, we evaluate the system performance by computer simulation.

The effect of a nonmagnetic hcp-underlayer on the epitaxial growth of CoCr19Pt10 magnetic layers on substrates of Al2O3(0001) single-crystal has been investigated. Thin films of (0001)-oriented single-crystal CoCr19Pt10 were obtained by employing non-magnetic underlayers of CoCr25Ru25 and CoCr25Ru25/Ti, while thin films of polycrystalline CoCr19Pt10 were grown after the deposition of underlayers of TiCr10 and CoCr40. The growth of thin film CoCr19Pt10 on a Ti(0001) underlayer was interpreted as quasi-hetero-epitaxial where the continuity of the lattice across the interface is disturbed while the overall crystallographic relationship between the two layers is maintained. A thin film of epitaxially grown CoCr19Pt10 has a compositional variation of a few percent across the film plane in terms of elements that forms the alloy.

An information retrieval model that intends to conceptually deal with the documents in the Internet is proposed. The first half of this model is a stage to select the documents, which may meet the user's long-term interests, by employing a filtering or retrieval system. The latter half is a stage for linear document arrangement and for adjacent cluster based browsing. For the document collection filtered out, similarity matrices are computed and then the documents are arranged such that the highly similar ones are adjacently placed. By this treatment the documents are considered to form the clusters, some of which are adjacently placed when they include similar documents. A user can satisfy her/his needs by first browsing in the clusters containing documents highly similar to a query, and next by extending the browsing process into the clusters adjacent to the ones just examined. In the adjacent clusters the documents having no keywords common to but conceptually related to the query can be found. Computational and statistical evaluations were done on two standard test collections. A virtual space navigator is also designed by using JAVA to assist a user in the browsing task.

Recently, neural networks (NNs) have been extensively applied to many signal processing problem due to their robust abilities to form complex decision regions. In particular, neural networks add flexibility to the design of equalizers for digital communication systems. Recurrent neural network (RNN) is a kind of neural network with one or more feedback loops, whereas self-organizing map (SOM) is characterized by the formation of a topographic map of the input patterns in which the spatial locations (i.e., coordinates) of the neurons in the lattice are indicative of intrinsic statistical features contained in the input patterns. In this paper, we propose a novel receiver structure by combining adaptive RNN equalizer with a SOM detector under serious ISI and nonlinear distortion in QAM system. According to the theoretical analysis and computer simulation results, the performance of the proposed scheme is shown to be quite effective in channel equalization under nonlinear distortion.

Low-profile inverter power supplies are increasingly required for backlight systems of liquid crystal displays (LCDs). A great deal of attention has been focused on the application of piezoelectric transformers (PTs) to such power supplies. To miniaturize PT inverters still further, PTs need to have sufficient high voltage-step-up-ratio, which can be achieved by a multilayered PT. First, this paper describes a method for simulating such performance using a distributed constant equivalent circuit model. The results of the simulation for a multilayered PT operated in the third order longitudinal vibration mode show that the resistance of internal electrodes causes the dominant loss factor. Next, a power inverter incorporating the multilayered PT was fabricated. This power inverter can be operated over a wide input DC voltage range from 7-20 V. Regarding a conventional inverter drive circuit, when input DC voltage range was extended, the inverter efficiency remarkably decreased. For the reason, we developed a new inverter circuit, which is equipped with an automatic drive voltage control circuit to maintain the drive voltage to the PT at a constant value. As a result, the fabricated power inverter exhibited more than 90% overall efficiency and 3.5 W output power, which is enough to light up a 12.1-inch color LCD. The maximum luminance efficiency on a light transmission plate of the backlight was as high as 30 cd/m2/W.

In this letter, an analysis of bit error probability of 4-state soft decision Viterbi decoding is presented. The bit error probability of recursive systematic convolutional code is also derived.

The EB tester line delay fault localization algorithm for combinational circuits is proposed where line delay fault probabilities are utilized to narrow fault candidates down to one efficiently. Probabilities for two main causes of line delay faults, defects of contact/vias along interconnections and crosstalk, are estimated through layout analysis. The algorithm was applied to 8 kinds of ISCAS'85 benchmark circuits to evaluate its performance where the guided probe (GP) diagnosis was used as the reference method. The proposed method can cut the number of probed lines to about 30% in average compared with those for the GP method. The total fault localization time was 31% of the time for the GP method and was 6% less than that of our previous method where the fault list generated in concurrent fault simulation is utilized.

In this paper, we propose an equalizer for indoor infrared wireless systems using on-off keying code-division multiple-access (OOK-CDMA). The proposed equalizer has a decision-feedforward filter to mitigate the effects of inter symbol interference (ISI) at the previous chip position of the sampling instant. We evaluate the performance of indoor infrared wireless systems using OOK-CDMA with three kinds of equalizers: the decision-feedback qualizer (DFE), the feedforward equalizer (FE), and the proposed equalizer. To estimate the impulse response, we use the training sequence that alternates '1' and '0' sequentially. Among three kinds of equalizers, we show that the system with the proposed equalizer can achieve the best bit error rate (BER) performance at high bit rate, while the system with the FE achieves the best BER performance when the bit rate is low.

This paper presents the transmission performance of a class-IV partial-response signaling SSB system and proposes a method that can improve its power efficiency. A line code that has no dc component has been used in the SSB transmission of digital signals. The type of line code, such as a partial-response signaling, increases the modulation states, and as a result, decreases the power efficiency. To overcome this obstacle, a new demodulation method called "re-filtering and combining" is proposed on the assumption of orthogonal phase detection. The demodulated quadrature channel is re-filtered by a Hilbert filter and is combined with the in-phase channel. It is confirmed by computer simulations that the new demodulation method improves the BER performance and a 3 dB improvement of the power efficiency is obtained.

This paper addresses a novel scheme for variable rate error correction coding with interleavered puncturing serially concatenated convolutional code. In order to obtain a variable coding rate, the bits of the outer coder are perforated with a given puncturing pattern, and randomly interleaved. The effect of interleavered puncturing on the overall coding performance is analyzed, and the upper bound to the bit error probability of the proposed coder is derived. Moreover, to evaluate the effectiveness of the proposed scheme some simulation results are presented with the iterative decoding procedure, in which the channel models of Rayleigh fading and additive white Gaussian noises are assumed.

Transmit diversity, a key technique derived against multi-path mitigation in wireless communication system, is examined and discussed. Especially, we present an approach to investigate perfect/imperfect channel detection when the maximal ratio receiver combined scheme (MRRC) and a simple transmit diversity scheme (STD) are used in the wireless systems, which provide remarkable schemes for diversity transmission over Rayleigh-fading channels using multiple antennas. In order to effectively make use of the transmit diversity techniques, the same approach is extended to process the situation of one transmit antennas and N receive antennas in MRRC scheme (1 N MRRC) and two transmit antennas and N receive antennas in STD scheme (2 N STD). The effects of perfect/imperfect channel detection and the diversity reception with independent and correlated Rayleigh-fading signals are evaluated and compared carefully.

In recent years, the domino logic has received much attention as a design technique of high-speed circuits. However, in the case of standard domino logic, only non-inverting functions are allowed. Then, the clock-delayed (CD) domino logic that provides any logic function is proposed in order to overcome such domino's drawback. In addition, domino circuits are more sensitive to circuit noise compared with static CMOS circuits. In particular, crosstalk causes critical problems. Therefore, we focus our attention on crosstalk faults in CD domino circuits. However, in CD domino circuits, there are faults that don't propagate faulty values to any primary output even though crosstalk pulses are generated. Then, we remove such faults from the target fault list by considering structures of CD domino circuits, and perform a fault simulation for the reduced target fault list using two kinds of fault simulation method together. We realize CD domino circuits in VHDL and perform the proposed fault simulation for the combinational part of some benchmark circuits of ISCAS'89 on a VHDL simulator. Fault coverage for random vectors was obtained for s27 to s1494 under the limitation of simulation time.