UWB pulse radars that offer target shape estimation are promising as imaging techniques for household or rescue robots. We have already proposed an efficient algorithm for a shape estimation method SEABED which is a fast algorithm based on a reversible transform. SEABED extracts quasi wavefronts from received signals with the filter that matches the transmitted waveform. However, the scattered waveform is, in general, different from the transmitted one depending on the shape of targets. This difference causes estimation errors in SEABED. In this paper, we propose an accurate algorithm for a polygonal-target based on scattered waveform estimation. The proposed method is presented first, followed by results of numerical simulations and experiments that show the efficiency of the proposed method.

Combined input and output queuing (CIOQ) switches are being considered as high-performance switch architectures due to their ability to achieve 100% throughput and perfectly emulate output queuing (OQ) switch performance with a small speedup factor S. To realize a speedup factor S, a conventional CIOQ switch requires the switching fabric and memories to operate S times faster than the line rate. In this paper, we propose to use a CIOQ switch with space-division multiplexing expansion and grouped input/output ports (SDMG CIOQ switch for short) to realize speedup while only requiring the switching fabric and memories to operate at the line rate. The cell scheduling problem for the SDMG CIOQ switch is abstracted as a bipartite k-matching problem. Using fluid model techniques, we prove that any maximal size k-matching algorithm on an SDMG CIOQ switch with an expansion factor 2 can achieve 100% throughput assuming input line arrivals satisfy the strong law of large numbers (SLLN) and no input/output line is oversubscribed. We further propose an efficient and starvation-free maximal size k-matching scheduling algorithm, kFRR, for the SDMG CIOQ switch. Simulation results show that kFRR achieves 100% throughput for SDMG CIOQ switches with an expansion factor 2 under two SLLN traffic models, uniform traffic and polarized traffic, confirming our analysis.

In this paper, we propose a robust statistical framework for extracting scenes from a baseball broadcast video. We apply multi-stream hidden Markov models (HMMs) to control the weights among different features. To achieve a large robustness against new scenes, we used a common simple structure for all the HMMs. In addition, scene segmentation and unsupervised adaptation were applied to achieve greater robustness against differences in environmental conditions among games. The F-measure of scene-extracting experiments for eight types of scene from 4.5 hours of digest data was 77.4% and was increased to 78.7% by applying scene segmentation. Furthermore, the unsupervised adaptation method improved precision by 2.7 points to 81.4%. These results confirm the effectiveness of our framework.

Binary sequences with good autocorrelation and crosscorrelation properties are widely used in signal processing. If the autocorrelation properties are optimum, then the sequences are called perfect. In this paper we show, that the calculation of the crosscorrelation between Gordon-Mills-Welch sequences and Dillon-Dobbertin sequences is related to the crosscorrelation of m-sequences and their decimations. Furthermore, we give an upper bound for the maximum crosscorrelation coefficient (in absolute value) for certain perfect sequences.

The Schaub bound is one of well-known lower bounds of the minimum distance for given cyclic code C, and defined as the minimum value, which is a lower bound on rank of matrix corresponding a codeword, in defining sequence for all sub-cyclic codes of given code C. In this paper, we will try to show relationships between the Schaub bound, the Roos bound and the shift bound from numerical experiments. In order to reduce computational time for the Schaub bound, we claim one conjecture, from numerical examples in binary and ternary cases with short code length that the Schaub bound can be set the value from only defining sequence of given code C.

A rigorous and simple method is proposed for analyzing guided modes of metallic electromagnetic crystal waveguides. The method is a combination of generalized reflection and transmission matrices and the mode-matching technique. Fast convergence, low computer cost, and high calculating precision are main advantages of the proposed method. This method can easily avoid the relative convergence phenomena than a classical mode-matching method, and the proposed formulation is very suitable to analyzing multilayered problems with very low computer cost. The existence of H-polarized modes in metallic electromagnetic crystal waveguides has been verified.

A novel structure for a frequency-independent steerable composite right/left-handed (CRLH) leaky wave (LW) antenna in the millimeter-wave band is proposed. This has the advantages of wide beam scanning and low profile, and is a suitable structure for mass-production. The proposed antenna has features wherein a movable dielectric slab is placed above the CRLH LW antenna, and the radiation angle can be steered by changing the distance between the slab and the antenna using compact actuators. Moreover, slots are added to the antenna to control the aperture amplitude distribution of the array antenna in order to enhance aperture efficiency. A prototype CRLH LW antenna has been fabricated with these slots, and backward-to-forward beam scanning characteristics at 76 GHz have been demonstrated successfully by measurement. A wide scanning angle from 73 to 114 deg. has been achieved experimentally. The aperture efficiency is 25.3%.

Several research fields have to deal with very large classification problems, e.g. handwritten character recognition and speech recognition. Many works have proposed methods to address problems with large number of samples, but few works have been done concerning problems with large numbers of classes. CombNET-II was one of the first methods proposed for such a kind of task. It consists of a sequential clustering VQ based gating network (stem network) and several Multilayer Perceptron (MLP) based expert classifiers (branch networks). With the objectives of increasing the classification accuracy and providing a more flexible model, this paper proposes a new model based on the CombNET-II structure, the CombNET-III. The new model, intended for, but not limited to, problems with large number of classes, replaces the branch networks MLP with multiclass Support Vector Machines (SVM). It also introduces a new probabilistic framework that outputs posterior class probabilities, enabling the model to be applied in different scenarios (e.g. together with Hidden Markov Models). These changes permit the use of a larger number of smaller clusters, which reduce the complexity of the final classifiers. Moreover, the use of binary SVM with probabilistic outputs and a probabilistic decoding scheme permit the use of a pairwise output encoding on the branch networks, which reduces the computational complexity of the training stage. The experimental results show that the proposed model outperforms both the previous model CombNET-II and a single multiclass SVM, while presenting considerably smaller complexity than the latter. It is also confirmed that CombNET-III classification accuracy scales better with the increasing number of clusters, in comparison with CombNET-II.

This paper studies the scattering of a TM plane wave from a perfectly conductive sinusoidal surface with finite extent by the small perturbation method. We obtain the first and second order perturbed solutions explicitly, in terms of which the differential scattering cross section and the total scattering cross section per unit surface are calculated and are illustrated in figures. By comparison with results by a numerical method, it is concluded that the perturbed solution is reasonable even for a critical angle of incidence if the surface is small in roughness and gentle in slope and if the corrugation width is less than certain value. A brief discussion is given on multiple scattering effects.

Similar to algebraic decoding schemes, the (23, 12, 7) Golay code can be decoded by applying the step-by-step decoding algorithm. In this work, a modified step-by-step algorithm for decoding the Golay code is presented. Logical analysis yielded a simple rule for directly determining whether a bit in the received word is correct. The computational complexity can be reduced significantly using this scheme.

An H.264-based selective FGS coding scheme is proposed. It selectively uses the interframe-prediction data inside the enhancement-layer only when those data can significantly reduce the temporal-redundancies. Since this minimizes the drift effects, the overall coding efficiency is improved. Simulations show that average PSNR of the proposed scheme is higher by 1-3 dB and 3-5 dB than those of the H.264-based FGS and the MPEG-4 video FGS profile, respectively.

Arc occurrence rates were measured for Ag contacts in DC resistive and inductive load circuits. In inductive load conditions, arc occurrence rates in general came close to 100% at around 0.4 A, the conventional minimum arc current level of Ag. In resistive load conditions, the similar results were obtained with 30 V, while arc occurrence rates close to 50% were still obtained at around 0.4 A with 14 V and 10 V. Careful attention should be paid to the term "minimum arc current" to avoid misinterpretation thereof.

We proposed a method for suppressing arc ignition in mechanical contact devices using a transient current switch and a capacitor. We applied the method to conventional reed switches. For the electric circuit analysis, we clarified the momentary voltage-current characteristics at breaking operation of reed switches by FEM analysis. We could also estimate the capacitance of the contact electrodes at the metal bridge rupture by FEM analysis, and would derive the non-arcing condition using SPICE simulation. The suitable capacitor value in the transient current circuit for arc ignition suppression would be depend on the load impedance, the power supply, the time depending contact resistance R(t)s, the contact capacitance, and the minimum arc voltage and current.

In difficult classification problems of the z-dimensional points into two groups giving 0-1 responses due to the messy data structure, we try to find the denser regions for the favorable customers of response 1, instead of finding the boundaries to separate the two groups. Such regions are called the bumps, and finding the boundaries of the bumps is called the bump hunting. The main objective of this paper is to find the largest region of the bumps under a specified ratio of the number of the points of response 1 to the total. Then, we may obtain a trade-off curve between the number of points of response 1 and the specified ratio. The decision tree method with the Gini's index will provide the simple-shaped boundaries for the bumps if the marginal density for response 1 shows a rather simple or monotonic shape. Since the computing time searching for the optimal trees will cost much because of the NP-hardness of the problem, some random search methods, e.g., the genetic algorithm adapted to the tree, are useful. Due to the existence of many local maxima unlike the ordinary genetic algorithm search results, the extreme-value statistics will be useful to estimate the global optimum number of captured points; this also guarantees the accuracy of the semi-optimal solution with the simple descriptive rules. This combined method of genetic algorithm search and extreme-value statistics use is new. We apply this method to some artificial messy data case which mimics the real customer database, showing a successful result. The reliability of the solution is discussed.

In this paper, the separation of heat generation and heat transfer related to temperature rise of silver palladium contact was investigated experimentally in order to predict the temperature rise of contact by the use conditions such as voltage range between 25 to 40 V, current range between 3.2 to 5.0 A and silver palladium alloy (AgPd) materials. Firstly, relationship between temperature rise of contact and supply power was discussed. The effects of heat generation and heat transfer on temperature rise were separated and quantified by least squares method. Secondly, effects of durations and integral powers of bridge and arc on temperature rise were also discussed by changing supply power. Results show that the integral power of the bridge increases when supply power increases. As the supply power increases, integral power of arc also increases. The temperature rise is dominated by integral power of bridge. Remarkable difference of bridge duration can not be seen in the five materials (AgPd30, AgPd40, AgPd50, AgPd70 and Pd). The supply power is increased, arc duration gets longer. As weight percent of Pd content increases, the effect of supply power on arc duration becomes larger. Consequently, the integral power of arc increases. This study is a basic consideration to realize methods predicting temperature rise of contact.

Numerous studies have shown that scaling exponents of internet traffic change over time or scaling ranges. In order to analyze long-range dependent traffic with changing scaling exponents over time scales, we propose a multi-scale traffic model that incorporates the notion of a piecewise self-similar process, a process with spectral changes on its scaling behavior. We can obtain a performance curve smoothened over the range of queue length corresponding to time scales with different scaling exponents by adopting multiple self-similar processes piecewise into different spectra of time scale. The analytical method for the multiscale fractional Brownian motion is discussed as a model for this approach. A comparison of the analytical and simulation results, using traffic data obtained from backbone networks, shows that our model provides a good approximation for Gaussian traffic.

Breaking arcs occurring between silver electrical contacts are observed in DC42 V resistive circuit using a high-speed camera. The motion and current densities of the cathode and anode spot regions are investigated for different interrupt currents (I=7 A, 10 A and 14 A). Results indicate that the arc length at which the motion of arc spots becomes stable depends on the interrupt current, and the current densities of the cathode spot region are almost constant immediately before arc extinction for each interrupt current.

This letter discusses how to enhance the capacity of uplink DS-CDMA networks that support multihop transmission. For this purpose, we derived simple theoretic conditions by which one can choose between singlehop- and multihop transmission. Numerical results show that we can significantly increase the radio network capacity by adopting only a few number of multihop transmissions.

This article presents the analysis of the Bragg scattering phenomenon which has been observed in the images of machine-planted rice paddies acquired by the JERS-1 L-band synthetic aperture radar (SAR). The simultaneous measurements of rice plants were made at the SAR data acquisition times. Large differences of 20-25 dB in image intensity between the transplanting and ripening stages are found to be dependent on the planting direction and bunch separation. This selective image enhancement is a result of the Bragg resonance backscatter due to the double-bounce of incident L-band microwave between the flooded water surface and periodically planted bunches of rice plants. Support for the idea of double-bounce scattering is provided by the decomposition analysis of L-band and X-band polarimetric Pi-SAR data; and a simple numerical simulation based on the physical optics model shows fairly good agreement with the JERS-1 SAR data. The results presented in this paper is mainly of academic interest, but a suggestion can be made on the selection of suitable microwave band for monitoring rice fields.

Arranging n points as uniformly as possible is a frequently occurring problem. It is equivalent to packing n equal and non-overlapping circles in a unit square. In this paper we generalize this problem in such a way that points are inserted one by one with uniformity preserved at every instance. Our criterion for uniformity is to minimize the gap ratio (which is the maximum gap over the minimum gap) at every point insertion. We present a linear time algorithm for finding an optimal n-point sequence with the maximum gap ratio bounded by in the 1-dimensional case. We describe how hard the same problem is for a point set in the plane and propose a local search heuristics for finding a good solution.