We have proposed a neural network called the Lagrange programming neural network with polarized high-order connections (LPPH) for solving the satisfiability problem (SAT) of propositional calculus. The LPPH has gradient descent dynamics for variables and gradient ascent dynamics for Lagrange multipliers, which represent the weights of the clauses of the SAT. Each weight wr increases according to the degree of unsatisfaction of clause Cr. This causes changes in the energy landscape of the Lagrangian function, on which the values of the variables change in the gradient descent direction. It was proved that the LPPH is not trapped by any point that is not a solution of the SAT. Experimental results showed that the LPPH can find solutions faster than existing methods. In the LPPH dynamics, a function hr(x) calculates the degree of unsatisfaction of clause Cr via multiplication. However, this definition of hr(x) has a disadvantage when the number of literals in a clause is large. In the present paper, we propose a new definition of hr(x) in order to overcome this disadvantage using the "min" operator. In addition, we extend the LPPH to solve the constraint satisfaction problem (CSP). Our neural network can update all neurons simultaneously to solve the CSP. In contrast, conventional discrete methods for solving the CSP must update variables sequentially. This is advantageous for VLSI implementation.

Recently, system level design languages (SLDL), which can describe both hardware and software aspects of the design, are receiving attention. Mixed-signal extensions of SLDL enable current discrete-oriented SLDLs to describe and simulate not only digital systems but also digital-analog mixed-signal systems. The synchronization between discrete and continuous behaviors is widely regarded as a critical part in the extensions. In this paper, we present an event-driven synchronization mechanism for both timed and untimed system level designs through which discrete and continuous behaviors are synchronized via AD events and DA events. We also demonstrate how the synchronization mechanism can be incorporated into the kernel of SLDL, such as SpecC. In the extended kernel, a new simulation cycle, the AMS cycle, is introduced. Three case studies show that the extended SpecC-based system level design environment using our synchronization mechanism works well with timed/untimed mixed-signal system level description.

We have proposed two space division multiple access (SDMA) approaches for OFDM signals: "Virtual Subcarrier Assignment (VISA)" and "Preamble Subcarrier Assignment (PASA)," both of which can enhance the system capacity without significant change of transmitter/receiver structures for already-existing OFDM-based standards such as IEEE802.11a. In order to investigate the performance of the proposed approaches in real wireless scenarios, we conducted a measurement campaign to obtain real channel state data at 5-GHz band in an indoor environment. Using the measured channel data, we can make the performance evaluation realistic. In this paper, after the brief overview of the two proposed SDMA approaches, we describe our measurement campaign in detail. Furthermore, we evaluate the performance of VISA-based system and PASA-based system by computer simulations using the measured channel state data and present a comparative study on the performance of the two proposed SDMA approaches in the realistic wireless environment.

A novel method is proposed to synthesize dual-band bandpass filters (BPFs) from a prototype lowpass filter. By implementing successive frequency transformations and circuit conversions, a new filter topology is obtained which consists of only admittance inverters and series or shunt resonators, and is thereby easy to be realized by using conventional distributed elements. A microstrip dual-band BPF with central frequencies of 1.8 GHz and 2.4 GHz is designed and fabricated using microstrip lines and stubs. The simulated and measured results show a good agreement and validate thereby the proposed theory.

This paper presents a design procedure of multilayer single-input/single-output dual-band filters of small size fabricated in high-permittivity LTCC (Low Temperature Co-fired Ceramic) substrates. The present dual-band filter, with pass bands of 950 MHz and 1.9 GHz, consists of two single-band filters each one of which has a matching circuit for controlling the input impedance in the pass band of the counterpart. Discussed first in this paper is a dual-band filter that has the matching circuit connected to the single-band filters externally. Then, a dual-band filter with the matching circuit embedded in its body is investigated together with metallization patterns of the matching elements. Presented finally is a very small single-input/single-output dual-band filter suitable for dual-band wireless communication systems.

This letter presents robustness bounds (RBs) for receding horizon controls (RHCs) of uncertain systems. The proposed RBs are obtained easily by solving convex problems represented by linear matrix inequalities (LMIs). We show, by numerical examples, that the RHCs can guarantee robust stabilization for a larger class of uncertain systems than conventional linear quadratic regulators (LQRs).

We propose optical wireless multiple-input multiple-output (OMIMO) communications to achieve high speed transmission with a compact transmitter and receiver. In OMIMO, by using zero forcing (ZF), minimum mean square error (MMSE) or other detection techniques, we can eliminate the interference from the other optical transmit antennas. In this paper, we employ ZF as the detection technique. We analyze the signal-to-interference-plus-noise ratio (SINR) and the bit error rate (BER) of the proposed OMIMO with a linear array and a square array of optical transmit and receive antennas, where we employ subcarrier multiplexing (SCM) for each optical transmit antenna. Note that the proposed OMIMO is applicable to other arrangements of optical transmit and receive antennas. We show that the proposed OMIMO system can realize MIMO multiplexing and achieve high speed transmission by correctly aligning the optical transmit and receive antennas and the transmitter semiangle.

This paper presents fingerprint image enhancement and rotation schemes that improve the identification accuracy with the pixel-parallel processing of pixels. In the schemes, the range of the fingerprint sensor is adjusted to the finger state, the captured image is retouched to obtain the suitable image for identification, and the image is rotated to the correct angle on the pixel array. Sensor and pixel circuits that provide these operations were devised and a test chip was fabricated using 0.25-µm CMOS and the sensor process. It was confirmed in 150,000 identification tests that the schemes reduce the false rejection rate to 6.17% from 30.59%, when the false acceptance rate is 0.1%.

This paper shows that the Surrounding Gate Transistor (SGT) can be scaled down to decananometer gate lengths by using an intrinsically-doped body and gate work function engineering. Strong gate controllability is an essential characteristics of the SGT. However, by using an intrinsically-doped body, the SGT can realize a higher carrier mobility and stronger gate controllability of the silicon body. Then, in order to adjust the threshold voltage, it is necessary to adopt gate work function engineering in which a metal or metal silicide gate is used. Using a three-dimensional (3D) device simulator, we analyze the short-channel effects and current characteristics of the SGT. We compare the device characteristics of the SGT to those of the Tri-gate transistor and Double-Gate (DG) MOSFET. When the silicon pillar diameter (or silicon body thickness) is 10 nm, the gate length is 20 nm, and the oxide thickness is 1 nm, the SGT shows a subthreshold swing of 63 mV/dec and a DIBL of -17 mV, whereas the Tri-gate transistor and the DG MOSFET show a subthreshold swing of 71 mV/dec and 77 mV/dec, respectively, and a DIBL of -47 mV and -75 mV, respectively. By adjusting the value of the gate work function, we define the off current at VG = 0 V and VD = 1 V. When the off current is set at 1 pA/µm, the SGT can realize a high on current of 1020 µA/µm at VG = 1 V and VD = 1 V. Moreover, the on current of the SGT is 21% larger than that of the Tri-gate transistor and 52% larger than that of the DG MOSFET. Therefore, the SGT can be scaled reliably toward the decananometer gate length for high-speed and low-power ULSI.

Hardware prototyping has been widely used for ASIC/SoC verification. This paper proposes a new hardware design verification method, Transition and Transaction Tracer (TTT), which probes and records the signals of interest for a long time, hours, days, or even weeks, without a break. It compresses the captured data in real time and stores it in a state transition format in memory. Since it records all the transitions, it is effective in finding and fixing errors, even ones that occur rarely or intermittently. It can also be programmed to generate a trigger for a logic analyzer when it detects certain transitions. This is useful for debugging situations where the engineer has trouble finding an appropriate trigger condition to pinpoint the source of errors. We have been using the method in hardware prototyping for ASIC/SoC development for two years and found it useful for system level tests, and in particular for long running tests.

This is commonly thought that CASE tools reduce programming efforts and increase development productivity. However, no paper has provide quantitative data supporting the matter. This paper discusses productivity improvement through the use of an integrated CASE tool system named EAGLE (Effective Approach to Achieving High Level Software Productivity), as shown by various data collected in Hitachi from the 1980s to the 2000s. We have evaluated productivity by using three metrics, l) program generation rate using reusable program skeletons and components, 2) fault density at two test phase, and 3) learning curve for the education of inexperienced programmers. We will show that productivity has been improved by the various facilities of EAGLE.

In software development, comprehensive software reviews and testings are important activities to preserve high quality and to control maintenance cost. However it would be actually difficult to perform comprehensive software reviews and testings because of a lot of components, a lack of manpower and other realistic restrictions. To improve performances of reviews and testings in object-oriented software, this paper proposes a novel model for detecting cost-prone classes; the model is based on Mahalanobis-Taguchi method--an extended statistical discriminant method merging with a pattern recognition approach. Experimental results using a lot of Java software are provided to statistically demonstrate that the proposed model has a high ability for detecting cost-prone classes.

Activity patterns of metabolic subnetworks, each of which can be regarded as a biological function module, were focused on in order to clarify biological meanings of observed deviation patterns of gene expressions induced by various chemical stimuli. We tried to infer association structures of genes by applying the multivariate statistical method called graphical Gaussian modeling to the gene expression data in a subnetwork-wise manner. It can be expected that the obtained graphical models will provide reasonable relationships between gene expressions and macroscopic biological functions. In this study, the gene expression patterns in nematodes under various conditions (stresses by chemicals such as heavy metals and endocrine disrupters) were observed using DNA microarrays. The graphical models for metabolic subnetworks were obtained from these expression data. The obtained models (independence graph) represent gene association structures of cooperativities of genes. We compared each independence graph with a corresponding metabolic subnetwork. Then we obtained a pattern that is a set of characteristic values for these graphs, and found that the pattern of heavy metals differs considerably from that of endocrine disrupters. This implies that a set of characteristic values of the graphs can representative a macroscopic biological meaning.

A planar composite right/left-handed leaky wave antenna which operates at W-band is fabricated and its backward to forward beam scanning operation including broadside direction is confirmed experimentally. The scanning angle from 61 to 114 degrees with a frequency scanning range of 76 to 79 GHz is achieved.

The analog IC technology, might sound old-fashioned, is still important for the future wireless systems such as 4G cellular phone systems, broadband wireless networkings, and wireless sensor networkings. The analog features and issues of the scaled CMOS transistor, the basic issue and the technology trend for the ADC as an important building block of wires systems, and the feature of the digital RF architecture proposed recently are reviewed and discussed. Higher speed and lower power consumption are expected for low SNR systems along with the further technology scaling. However, the high SNR system is not realized easily due to a decrease of signal voltage. One of the important technology trends is the digitalization of RF signal to realize the system flexibility, robustness, area shrinking, and TAT shortening.

The effect of the power/ground plane on the through-hole signal via is analyzed in a viewpoint of a band-stop filter. When the through-hole signal via passes through the power/ground plane, the return current path discontinuity of the through-hole signal via occurs due to the high impedance of the power/ground plane. Since the high impedance is produced by the power/ground plane resonance, it acts as a band-stop filter, which is connected to the signal trace in series. Therefore, the power/ground plane filters off its resonance frequency component by absorbing and reflecting from the signal on the through-hole signal via, and consequently the signal distortion, the power/ground plane noise voltage, and the consequent radiated emission occur. With S-parameter and TDR-TDT measurements, the band-stop effect of the power/ground plane on the through-hole signal via is confirmed. And then, this analysis is applied to the clock transmission through the through-hole signal via to obtain the clearer confirmation. The measurements of the distorted clock waveforms, the induced power/ground plane noise voltages, and the radiated emissions depending on the power/ground plane impedance around the through-hole signal via are shown.

For various applications in image, communications and signal processing, two-dimensional (2-D) generalized orthogonal (GO) sequences, that is, 2-D sequences with zero correlation zone (ZCZ) and 2-D complementary orthogonal (CO) sequences with ZCZ, are widely investigated. New lower bounds for 2-D GO sequences, based on matrix theory on rank, are derived and presented, some examples that attain these lower bounds are given. As a direct application to our results, upper bound on family size of 2-D mutually complementary orthogonal (MCO) codes defined by Luke [9] is proposed.

We consider a watermark application to assist in the integrity maintenance and verification of the associated images. There is a great benefit in using WM in the context of authentication since it does not require any additional storage space for supplementary metadata, in contrast with cryptographic signatures, for instance. However there is a fundamental problem in the case of exact authentication: How to embed a signature into a cover message in such a way that it would be possible to restore the watermarked cover image into its original state without any error? There are different approaches to solve this problem. We use the watermarking method consisting of modulo addition of a mark and investigate it in detail. Our contribution lies in investigating different modified techniques of both watermark embedding and detection in order to provide the best reliability of watermark authentication. The simulation results for different types of embedders and detectors in combination with the pictures of watermarked images are given.

We theoretically analyze the performance of coherent ultrashort light pulse code-division multiple-access (CDMA) communication systems with a nonlinear optical thresholder. The coherent ultrashort light pulse CDMA is a promising system for an optical local area network (LAN) due to its advantages of asynchronous transmission, high information security, multiple access capability, and optical processing. The nonlinear optical thresholder is based on frequency chirping induced by self-phase modulation (SPM) in optical fiber, and discriminates an ultrashort pulse from multiple access interference (MAI) with picosecond duration. The numerical results show that the thermal noise caused in a photodetector dominates the bit error rate (BER). BER decreases as the fiber length in the nonlinear thresholder and the photocurrent difference in the photodetector increase. Using the nonlinear optical thresholder allows for the response time of the photodetector to be at least 100 times the duration of the ultrashort pulses. We also show that the optimum cut-off frequency at the nonlinear thresholder to achieve the minimum BER increases with fiber length, the total number of users, and the load resistance in the photodetector.

Genetic Algorithm (GA) and other Evolutionary Algorithms (EAs) have been successfully applied to solve constrained minimum spanning tree (MST) problems of the communication network design and also have been used extensively in a wide variety of communication network design problems. Choosing an appropriate representation of candidate solutions to the problem is the essential issue for applying GAs to solve real world network design problems, since the encoding and the interaction of the encoding with the crossover and mutation operators have strongly influence on the success of GAs. In this paper, we investigate a new encoding crossover and mutation operators on the performance of GAs to design of minimum spanning tree problem. Based on the performance analysis of these encoding methods in GAs, we improve predecessor-based encoding, in which initialization depends on an underlying random spanning-tree algorithm. The proposed crossover and mutation operators offer locality, heritability, and computational efficiency. We compare with the approach to others that encode candidate spanning trees via the Pr?fer number-based encoding, edge set-based encoding, and demonstrate better results on larger instances for the communication spanning tree design problems.