A novel circularly polarized antenna with square slot for broadband characteristics is proposed in this paper. The horizontal and vertical components of the L-shaped probe, which is a key element to generate circular polarization, are separated in the structure, contrary to the concept of joined probes. Another novelty, placing stubs in the slot, which are attached to the ground plane, is proposed to improve the axial ratio (AR) characteristics of the antenna by around 10%. Placing a reflector at a distance of λ0/4 from the antenna to obtain unidirectional patterns is effective when no stubs are placed in the slot. The antenna attains a < 10 dB return loss bandwidth of 47.5% (2.76-4.48 GHz) and < 3 dB axial ratio (AR) bandwidth of 42.47% (2.67-4.11 GHz) in measurement. Parametric studies on key parameters and measured results are also presented.

Precise estimation of data distribution with a small number of sample patterns is an important and challenging problem in the field of statistical pattern recognition. In this paper, we propose a novel method for estimating multimodal data distribution based on the Gaussian mixture model. In the proposed method, multiple random vectors are generated after classifying the elements of the feature vector into subsets so that there is no correlation between any pair of subsets. The Gaussian mixture model for each subset is then constructed independently. As a result, the constructed model is represented as the product of the Gaussian mixture models of marginal distributions. To make the classification of the elements effective, a graph cut technique is used for rearranging the elements of the feature vectors to gather elements with a high correlation into the same subset. The proposed method is applied to a character recognition problem that requires high-dimensional feature vectors. Experiments with a public handwritten digit database show that the proposed method improves the accuracy of classification. In addition, the effect of classifying the elements of the feature vectors is shown by visualizing the distribution.

A solution-processed red-sensitive organic photoconductive device was demonstrated by using soluble nickel-phthalocyanine. We found that a ratio of four nickel-phthalocyanine regioisomers was important factor for the high optical-electrical conversion efficiency. A maximum external quantum efficiency of device of 0.83% was achieved by optimizing the device structure.

Pairing-based cryptosystems are generally constructed using many functions such as pairing computation, arithmetic in finite fields, and arithmetic on elliptic curves. MapToPoint, which is a hashing algorithm onto an elliptic curve point, is one of the functions for constructing pairing-based cryptosystems. There are two MapToPoint algorithms on supersingular elliptic curves in characteristic three, which is used by ηT pairing. The first is computed by using a square root computation in F3m, and the computational cost of this algorithm is O(log m) multiplications in F3m. The second is computed by using an (m-1)(m-1) matrix over F3. It can be computed by O(1) multiplications in F3m. However, this algorithm needs the off-line memory to store about m F3m-elements. In this paper, we propose an efficient MapToPoint algorithm on the supersingular elliptic curves in characteristic three by using 1/3-trace over F3m. We propose 1/3-trace over F3m, which can compute solution x of x3 -x = c by using no multiplication in F3m. The proposed algorithm is computed by O(1) multiplications in F3m, and it requires less than m F3-elements to be stored in the off-line memory to efficiently compute trace over F3m. Moreover, in our software implementation of F3509, the proposed MapToPoint algorithm is approximately 35% faster than the conventional MapToPoint algorithm using the square root computation on an AMD Opteron processor (2.2 GHz).

In this letter, we generalize the binary sequence introduced by Li et al. in [S. Q. Li et al., On the randomness generalized cyclotomic sequences of order two and length pq, IEICE Trans. Fund, vol. E90-A, no.9, pp.2037-2041, 2007] to sequence over arbitrary prime fields. Furthermore, the auto-correlation distribution and linear complexity of the proposed sequence are presented.

Scattering characteristics of a domain wall displacement detection (DWDD) disk with a control layer were investigated by finite-difference time-domain (FDTD) analysis. DWDD is one of the high-density storage technologies of magneto-optical (MO) disks and the control layer is used to suppress ghost signals due to a rear process. The effects of the control layer on the scattering characteristics were studied.

In this paper, we discuss the validity of the multi-scale gamma model and characterize the differences in host-level application traffic with this model by using a real traffic trace collected on a 150-Mbps transpacific link. First, we investigate the dependency of the model (parameters α and β, and fitting accuracy ε) on time scale Δ, then find suitable time scales for the model. Second, we inspect the relations among α, β, and ε, in order to characterize the differences in the types of applications. The main findings of the paper are as follows. (1) Different types of applications show different dependencies of α, β, and ε on Δ, and display different suitable Δs for the model. The model is more accurate if the traffic consists of intermittently-sent packets than other. (2) More appropriate models are obtained with specific α and β values (e.g., 0.1 < α < 1, and β < 2 for Δ = 500 ms). Also, application-specific traffic presents specific ranges of α, β, and ε for each Δ, so that these characteristics can be used in application identification methods such as anomaly detection and other machine learning methods.

This paper describes a spatial fading emulator based on Clarke's model that can evaluate spatial correlation characteristics between signals received by handset antennas including human-body effect under emulated multipath propagation environments. The proposed model is composed of scatterers, phase-shifters and attenuators. The scatterers are located at equal intervals on the circumference of a circle. Phase shifters and attenuators in a control circuit are used to control the phase and amplitude of each wave radiated from the scatterers in order to emulate multi-path propagation environments, such as Rayleigh or Nakagami-Rice distribution, to be generated at their center. In this paper, the maximum distance between receiving antennas that could be used to evaluate spatial correlation characteristics between antennas was investigated experimentally. The measurement results show that 15 scatterers with a radius of 1.5 m are sufficient to evaluate spatial correlation characteristics within the branch separation of 1.7 λ when parallel dipole antennas are used as receiving antennas.

Readout characteristics of a near-field optical disk with an acute-edged metallic nano-aperture were investigated. The electromagnetic field distributions of the near field around the aperture were analyzed, and the far-field scattering of the waves transmitted through the phase change disk was calculated by finite-difference time-domain method into which motion equations of free electrons were incorporated. Adjusting the edge angle of the aperture increased the field intensity of near-field light. The influence of the edge angle on output through the recorded mark was also investigated. It was found that there is an optimum edge angle that differs depending on the aperture width.

In this paper we clarify for the boost and the buck-boost converter that the ripple effect is not ignorable for the frequency response, and reveal that it causes the unexpected characteristics where either the phase lag or the phase lead appears depending on the shape of waveform of the ramp generator in the PWM circuit. Eventually the phase margin for the stability drastically changes depending on the slope direction (normal or reverse) of the sawtooth waveform of the ramp generator even in the same circuit configuration. For the ripple effects we propose the general analysis model and analyze them of the boost and the buck-boost converters. As the result we identify that the ripple effects are caused mainly by the variation of the slope and the average of the ripple, and reveal that the both converters have the asymmetric characteristics for the slope direction of the sawtooth waveform of the ramp generator and there is more advantage for the stability in case of the reverse slope direction than in case of the normal one. It also clarified that the effect of ESR of the output capacitor of the converter on the frequency response is different according to the shape of the sawtooth waveforms. The proposed analysis method is validated by the experiments and simulations.

The dynamic characteristics are the key issues in the optimum design of a permanent magnetic actuator (PMA). A new approach to forecast the dynamic characteristics of the multilink PMA is proposed. By carrying out further developments of ADAMS and ANSOFT, a mathematic calculation model describing the coupling of mechanical movement, electric circuit and magnetic field considering eddy current effect, is constructed. With this model, the dynamic characteristics of the multilink PMA are calculated and compared with the experimental results. Factors that affect the opening time of the multilink PMA are analyzed with the model as well. The method is capable of providing a reference for the design of the PMA.

We derive physics-based formula of current-voltage characteristic for resonant tunneling diodes (RTDs) by using the Voigt function. The Voigt function describes the mixing condition of homogeneous and inhomogeneous broadenings of peak energy width in transmission probability, which is sensitively reflected to nonlinear negative differential resistance of RTDs. The obtained formula is applicable to the SPICE model of RTD without performing numerical integrals. We indicate validity of the formula by comparing to measured data for double-barrier and triple-barrier RTDs.

We propose a character size optimization technique to reduce the number of EB shots of multi-column-cell (MCC) lithographic systems in which transistor patterns are projected with multiple column cells in parallel. Each and every column cell is capable of projecting patterns with character projection (CP) and variable shaped beam (VSB) methods. Seeking the optimal character size of characters contributes to minimizing the number of EB shots and reducing the fabrication cost for ICs. Experimental results show that the character size optimization achieved 70.6% less EB shots in the best case with an available electron beam (EB) size. Our technique also achieved 40.6% less EB shots in the best case than a conventional character sizing technique.

In this paper, we utilize low temperature co-fired ceramic technology (LTCC) to realize a modified short-circuited stub bandpass filter suitable for ultra-wideband (UWB) applications. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate (∈ r = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter is fabricated and measurement results show that it has an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49% has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are 480.57 mm3.

An analog circuit testing scheme is presented. The testing technique is a sinusoidal fault signature characterization, involving the measurement of DC offset, amplitude, frequency and phase shift, and the realization of two crossing level voltages. The testing system is an extension of the IEEE 1149.4 standard through the modification of an analog boundary module, affording functionalities for both on-chip testing capability, and accessibility to internal components for off-chip testing. A demonstrating circuit-under-test, a 4th-order Gm-C low-pass filter, and the proposed analog testing scheme are implemented in a physical level using 0.18-µm CMOS technology, and simulated using Hspice. Both catastrophic and parametric faults are potentially detectable at the minimum parameter variation of 0.5%. The fault coverage associated with CMOS transconductance operational amplifiers and capacitors are at 94.16% and 100%, respectively. This work offers the enhancement of standardizing test approach, which reduces the complexity of testing circuit and provides non-intrusive analog circuit testing.

A Multi-Property-Preserving (MPP) hash function is a hash function that simultaneously preserves several security properties of the underlying compression function. The Merkle-Damgård with a Permutation (MDP) was shown to preserve unforgeability and pseudorandom oracle property. In this paper, we consider the most basic security properties of hash functions, namely collision resistance, second-preimage resistance, and preimage-resistance. We first show which of these properties are preserved by MDP in the dedicated-key setting. We also identify the properties preserved by four variants of MDP, and five other variants of Merkle-Damgård iterated hash functions. As a result, for the ten hash functions we analyze, we obtain their complete MPP characteristics.

High Dynamic Range Imaging (HDRI) refers to a set of techniques that can represent a dynamic range of real world luminance. Hence, the HDR image can be used to measure the reflectance property of materials. In order to reproduce the original color of materials using this HDR image, characterization of HDR imaging is needed. In this study, we propose a new HDRI characterization method under a known illumination condition at the HDR level. The proposed method normalizes the HDR image by using the HDR image of a light and balances the tone using the reference of the color chart. We demonstrate that our method outperforms the previous method at the LDR level by the average color difference and BRDF rendering result. The proposed method gives a much better reproduction of the original color of a given material.

In this paper, we present a discriminative word-character hybrid model for joint Chinese word segmentation and POS tagging. Our word-character hybrid model offers high performance since it can handle both known and unknown words. We describe our strategies that yield good balance for learning the characteristics of known and unknown words and propose an error-driven policy that delivers such balance by acquiring examples of unknown words from particular errors in a training corpus. We describe an efficient framework for training our model based on the Margin Infused Relaxed Algorithm (MIRA), evaluate our approach on the Penn Chinese Treebank, and show that it achieves superior performance compared to the state-of-the-art approaches reported in the literature.

To obtain text information included in a scene image, we first need to extract text regions from the image before recognizing the text. In this paper, we examine human vision and propose a novel method to extract text regions by evaluating textural variation. Human beings are often attracted by textural variation in scenes, which causes foveation. We frame a hypothesis that texts also have similar property that distinguishes them from the natural background. In our method, we calculate spatial variation of texture to obtain the distribution of the degree of likelihood of text region. Here we evaluate the changes in local spatial spectrum as the textural variation. We investigate two options to evaluate the spectrum, that is, those based on one- and two-dimensional Fourier transforms. In particular, in this paper, we put emphasis on the one-dimensional transform, which functions like the Gabor filter. The proposal can be applied to a wide range of characters mainly because it employs neither templates nor heuristics concerning character size, aspect ratio, specific direction, alignment, and so on. We demonstrate that the method effectively extracts text regions contained in various general scene images. We present quantitative evaluation of the method by using databases open to the public.

The cooperative characteristics of electromagnetic relay's attraction torque and reaction torque are the key property to ensure its reliability, and it is important to attain better cooperative characteristics by analyzing and optimizing relay's electromagnetic system and mechanical system. From the standpoint of changing reaction torque of mechanical system, in this paper, adjusted parameters (armature's maximum angular displacement αarm_max, initial return spring's force Finiti_return_spring, normally closed (NC) contacts' force FNC_contacts, contacts' gap δgap, and normally opened (NO) contacts' over travel δNO_contacts) were adopted as design variables, and objective function was provided for with the purpose of increasing breaking velocities of both NC contacts and NO contacts. Finally, genetic algorithm (GA) was used to attain optimization of the objective function. Accuracy of calculation for the relay's dynamic characteristics was verified by experiment.