The characteristics of violet-sensitive organic photodetectors (OPDs) utilizing polyalkylfluorene and triplet materials have been studied as a host and a dopant material, respectively. For the photo absorption layer, poly(9,9-dioctylfluorene) [PFO] and a phosphorescent iridium complex (Iridium (III) bis(2-(4,6-difluorophenyl)pyridinato-N,C2) [FIrpic] or Iridium (III) bis(2-(2'-benzothienyl)pyridinato-N,C3')(acetyl-acetonate) [(btp)2Ir(acac)]) were used as a host and a dopant material, respectively. PFO: (btp)2Ir(acac) device showed less photocurrent than PFO device because (btp)2Ir(acac) enhances recombination of the photo generated carriers in the photo absorption layer. On the other hand, PFO : FIrpic device showed larger photocurrent than PFO device due to triplet energy transfer from FIrpic to PFO. A cutoff frequency of 20 MHz was observed using a sinusoidal modulated violet laser light illumination under the reverse bias of 8 V.

This paper proposes a distributed stream multiplexing architecture for video codec LSIs with multi-chip configuration. This distributed architecture utilizes a built-in media multiplexing unit with an external stream input and inter-chip communication interfaces. Parallel protocol processing, with an autonomous inter-chip control mechanism to mix and concatenate packets through daisy-chained transfer paths, provides a complete multi-chip stream output at the end of the chain. Dispensing with external post-processing devices contributes to both high throughput and downsizing of high-end video codec systems. It is configurable for parallel encoding of super high-resolution video, multi-view/-angled HDTV vision and multiple HDTV programs. The architecture was successfully implemented in a fabricated single-chip MPEG-2 422P@HL codec LSI and utilized for the development of a super high-resolution video codec system.

Multi-Car Elevator (MCE) systems, which consist of several independent cars built in the same shaft, are being considered as the elevators of the next generation. In this paper, we present MceSim, a simulator of MCE systems. MceSim is an open source software available to the public, and it can be used as a common testbed to evaluate different control methods related to MCE systems. MceSim was used in the group controller performance competition: CST Solution Competition 2007. This experience has proven MceSim to be a fully functional testbed for MCE systems.

We propose a flexible video CODEC system for super-high-resolution videos such as those utilizing 4k2k pixel. It uses the spatially parallel encoding approach and has sufficient scalability for the target video resolution to be encoded. A video shift and padding function has been introduced to prevent the image quality from being degraded when different active line systems are connected. The switchable cascade multiplexing function of our system enables various super-high-resolutions to be encoded and super-high-resolution video streams to be recorded and played back using a conventional PC. A two-stage encoding method using the complexity of each divided image has been introduced to equalize encoding quality among multiple divided videos. System Time Clock (STC) sharing has also been implemented in this CODEC system to absorb the disparity in the times streams are received between channels. These functions enable highly-efficient, high-quality encoding for super-high-resolution video.

This paper proposes a closed form solution to L2-sensitivity minimization of second-order state-space digital filters subject to L2-scaling constraints. The proposed approach reduces the constrained optimization problem to an unconstrained optimization problem by appropriate variable transformation. Furthermore, restricting ourselves to the case of second-order state-space digital filters, we can express the L2-sensitivity by a simple linear combination of exponential functions and formulate the L2-sensitivity minimization problem by a simple polynomial equation. As a result, L2-sensitivity is expressed in closed form, and its minimization subject to L2-scaling constraints is achieved without iterative calculations.

This paper presents a new method for reconstruction of trigonometric polynomials, a specific class of bandlimited signals, from a number of integrated values of input signals. It is applied in signal reconstruction, spectral estimation, system identification, as well as in other important signal processing problems. The proposed method of processing can be used for precise rms measurements of periodic signal (or power and energy) based on the presented signal reconstruction. Based on the value of the integral of the original input (analogue) signal, with a known frequency spectrum but unknown amplitudes and phases, a reconstruction of its basic parameters is done by the means of derived analytical and summarized expressions. Subsequent calculation of all relevant indicators related to the monitoring and processing of ac voltage and current signals is provided in this manner. Computer simulation demonstrating the precision of these algorithms. We investigate the errors related to the signal reconstruction, and provide an error bound around the reconstructed time domain waveform.

This paper proposes a closed form solution to L2-sensitivity minimization of second-order state-space digital filters. Restricting ourselves to the second-order case of state-space digital filters, we can express the L2-sensitivity by a simple linear combination of exponential functions and formulate the L2-sensitivity minimization problem by a simple polynomial equation. As a result, the L2-sensitivity minimization problem can be converted into a problem to find the solution to a fourth-degree polynomial equation of constant coefficients, which can be algebraically solved in closed form without iterative calculations.

This paper considers numerical methods for stability analyses of periodic solutions of ordinary differential equations. Stability of a periodic solution can be determined by the corresponding monodromy matrix and its eigenvalues. Some commonly used numerical methods can produce inaccurate results of them in some cases, for example, near bifurcation points or when one of the eigenvalues is very large or very small. This work proposes a numerical method using a periodic boundary condition for vector fields, which preserves a critical property of the monodromy matrix. Numerical examples demonstrate effectiveness and a drawback of this method.

The subject of this paper is maximum weight matchings of graphs. An edge set M of a given graph G is called a matching if and only if any pair of edges in M share no endvertices. A maximum weight matching is a matching whose total weight (total sum of edge-weights) is maximum among those of G. The maximum weight matching problem (MWM for short) is to find a maximum weight matching of a given graph. Polynomial algorithms for finding an optimum solution to MWM have already been proposed: for example, an O(|V|4) time algorithm proposed by J. Edmonds, and an O(|E||V|log |V|) time algorithm proposed by H.N. Gabow. Some applications require obtaining a matching of large total weight (not necessarily a maximum one) in realistic computing time. These existing algorithms, however, spend extremely long computing time as the size of a given graph becomes large, and several fast approximation algorithms for MWM have been proposed. In this paper, we propose six approximation algorithms GRS+, GRS_F+, GRS_R+, GRS_S+, LAM_a+ and LAM_as+. They are enhanced from known approximation ones by adding some postprocessings that consist of improved search of weight augmenting paths. Their performance is evaluated through results of computing experiment.

A branch-and-bound algorithm (BB for short) is the most general technique to deal with various combinatorial optimization problems. Even if it is used, computation time is likely to increase exponentially. So we consider its parallelization to reduce it. It has been reported that the computation time of a parallel BB heavily depends upon node-variable selection strategies. And, in case of a parallel BB, it is also necessary to prevent increase in communication time. So, it is important to pay attention to how many and what kind of nodes are to be transferred (called sending-node selection strategy). In this paper, for the graph coloring problem, we propose some sending-node selection strategies for a parallel BB algorithm by adopting MPI for parallelization and experimentally evaluate how these strategies affect computation time of a parallel BB on a PC cluster network.

This study proposes a method to decompose a signal into a set of periodic signals. The proposed decomposition method imposes a penalty on the resultant periodic subsignals in order to improve the sparsity of decomposition and avoid the overestimation of periods. This penalty is defined as the weighted sum of the l2 norms of the resultant periodic subsignals. This decomposition is approximated by an unconstrained minimization problem. In order to solve this problem, a relaxation algorithm is applied. In the experiments, decomposition results are presented to demonstrate the simultaneous detection of periods and waveforms hidden in signal mixtures.

An important issue in the realization of optical packet-switched (OPS) networks is the resolution of packet contention caused by the lack of RAM-like optical buffering. Although an optical buffer using fiber delay lines (FDLs) has been proposed, its capacity is extremely limited. There have been several studies of this problem. One approach is deflection routing, which is widely used in electronic packet-switched networks or optical burst-switched (OBS) networks. However, in OPS networks, packet lengths are short, so that the speed requirement for route lookup is very stringent. If the network topology is geometric, such as a Manhattan Street Network (MSN), hop-by-hop routing can be implemented by simple optical logic devices without an electronic routing table. However, if the topology is not geometric, it is hard to implement deflection routing electronically or optically. Another approach is reflection routing, which is easy to implement but has a higher probability of packet loss than does deflection routing. In this paper, we propose a packet contention resolution scheme, reflection-based deflection routing, which is based on reflection routing and enables switching the reflected packet to an alternate path if its primary path remains congested. Our method alleviates the time limitation on setting an alternate path by making use of the packet reflection latency and also reduces the probability of packet loss. We evaluate the performance of the proposed method by simulation experiments and show its effectiveness.

In this paper, we propose a method that recovers a smooth high-resolution image from several blurred and roughly quantized low-resolution images. For compensation of the quantization effect we introduce measurements of smoothness, Huber function that is originally used for suppression of block noises in a JPEG compressed image [Schultz & Stevenson '94] and a smoothed version of total variation. With a simple operator that approximates the convex projection onto constraint set defined for each quantized image [Hasegawa et al. '05], we propose a method that minimizes these cost functions, which are smooth convex functions, over the intersection of all constraint sets, i.e. the set of all images satisfying all quantization constraints simultaneously, by using hybrid steepest descent method [Yamada & Ogura '04]. Finally in the numerical example we compare images derived by the proposed method, Projections Onto Convex Sets (POCS) based conventinal method, and generalized proposed method minimizing energy of output of Laplacian.

In this letter, a semi-automatic method for road network extraction from high-resolution satellite images is proposed. First, we focus on detecting the seed points in candidate road regions using a method of self-organizing map (SOM). Then, an approach to road tracking is presented, searching for connected points in the direction and candidate domain of a road. A study of Geographical Information Systems (GIS) using high-resolution satellite images is presented in this letter. Experimental results verified the effectiveness and efficiency of this approach.

We have derived the novel extended UTD (Uniform Geometrical Theory of Diffraction) solution and the novel modified UTD solution for the back scattering of an incident whispering gallery (WG) mode on the edge of a cylindrically curved conducting sheet. By comparing with the reference solution obtained from the integral representation of the scattered field by integrating numerically along the integration path, we have confirmed the validity and the utility of the novel asymptotic solutions proposed in the present study. It is shown that the extended UTD solution can be connected smoothly to the modified UTD solution on the geometrical boundary separating the edge-diffracted ray and the surface-diffracted ray.

Most learning-based super-resolution methods neglect the illumination problem. In this paper we propose a novel method to combine blind single-frame super-resolution and shadow removal into a single operation. Firstly, from the pattern recognition viewpoint, blur identification is considered as a classification problem. We describe three methods which are respectively based on Vector Quantization (VQ), Hidden Markov Model (HMM) and Support Vector Machines (SVM) to identify the blur parameter of the acquisition system from the compressed/uncompressed low-resolution image. Secondly, after blur identification, a super-resolution image is reconstructed by a learning-based method. In this method, Logarithmic-wavelet transform is defined for illumination-free feature extraction. Then an initial estimation is obtained based on the assumption that small patches in low-resolution space and patches in high-resolution space share a similar local manifold structure. The unknown high-resolution image is reconstructed by projecting the intermediate result into general reconstruction constraints. The proposed method simultaneously achieves blind single-frame super-resolution and image enhancement especially shadow removal. Experimental results demonstrate the effectiveness and robustness of our method.

This paper introduces a texture analysis mechanism utilizing multiresolution technique to reduce false motion detection and hence thoroughly improve the interpolation results for high-quality deinterlacing. Conventional motion-adaptive deinterlacing algorithm selects from inter-field and intra-field interpolations according to motion. Accurate determination of motion information is essential for this purpose. Fine textures, having high local pixel variation, tend to cause false detection of motion. Based on hierarchical wavelet analysis, this algorithm provides much better perceptual visual quality and considerably higher PSNR than other motion adaptive deinterlacers as shown. In addition, a recursive 3-field motion detection algorithm is also proposed to achieve better performance than the traditional 2-field motion detection algorithm with little memory overhead.

High-resolution Direction-of-Arrival (DOA) estimation techniques for antenna arrays have been widely desired in many applications such as smart antennas, RF position location, and RFID system. To realize high-resolution capability of the techniques, precise array calibration is necessary. For an array of single-mode elements, a calibration matrix derived by the open-circuit method is the simplest one. Unfortunately, calibration performance of the method is not enough for the high-reslution DOA estimation techniques. In this paper, we consider problems of the calibration matrix derived by the method, and show that errors in the matrix can be effectively removed by an optimal diagonal weight coefficient. In the proposed compensation technique, the number of newly introduced parameters, or unknowns, is only one for an array of the identical elements. Performance of the simple compensation technique is verified numerically and experimentally.

In this paper, an ultra-low power variable-resolution sigma-delta (ΣΔ) modulator for biomedical application is presented. The resolution of proposed modulator can be adjusted by switching its sampling frequency and architecture. The architecture is switched between second-order single-loop modulator and fourth-order cascaded second stage noise shaped modulator to reach different resolution requirement. The proposed sigma-delta modulator is implemented by single phase integrators based on a fully differential switched-capacitor circuit. The digital cancellation logic is embedded in the chip so that it would easily be integrated with biomedical instrument for effective acquisition. Experimental results of the proposed variable-resolution ΣΔ modulator fabricated in standard CMOS 0.18 µm technology confirm the expected specifications from 65 dB signal-to-noise distortion to 96 dB with 1 kHz bandwidth and power consumption range from 48 µW to 360 µW with a 1.8 V battery supply.

As a powerful computational test for nonexistence of a DC solution of a nonlinear circuit, the LP test is well-known. This test is useful for finding all solutions of nonlinear circuits; it is also useful for verifying the nonexistence of a DC operating point in a given region where operating points should not exist. However, the LP test has not been widely used in practical circuit simulation because the programming is not easy for non-experts or beginners. In this paper, we propose a new LP test that can be easily implemented on SPICE without programming. The proposed test is useful because we can easily check the nonexistence of a solution using SPICE only.