This paper addresses the variation of the attenuation characteristics of the Specific Absorption Rate (SAR) in a lossy medium as a function of the distance between an antenna and the medium with different EM-source sizes. Analysis and measurements were performed using a dipole antenna at 900 MHz and a COST244 cubic phantom. From this, an empirical equation has been derived, representing the attenuation characteristics of the SAR. The equation takes into consideration an energy loss due to the spatial spread of electromagnetic waves. In the case where an antenna is placed more than λ/2π away from the medium, the attenuation characteristics of the SAR are those obtained from plane waves in the lossy medium. In the case where a half-wavelength dipole antenna is located close to the medium, at a distance of less than λ/2π, the attenuation characteristics of the SAR are calculated from an equation that includes a loss caused by the spread of energy as a cylindrical wave. Moreover, when the length of antenna is short, it is found that a spatial attenuation factor appropriate to a spherical wave should be taken into account.

In a direct conversion receiver for mobile communication, it is important to reduce power dissipation. Because a low pass filter in a direct conversion receiver must suppress adjacent channel signals, a high order and high power dissipation is often required in the low pass filter. We propose a new phase compensation technique suitable for a low power transconductor used in a GmC filter as a low pass filter. The new phase compensation technique reduces 10% of power dissipation.

The three beam-switched top-loaded antenna is suited to be applied to a wireless local area network to switch the radiation pattern by arranging several unidirectional antennas. In this paper, a three beam switched top loaded monopole antenna is proposed to realize its small size and planar structure. Three top loaded monopole antennas are arranged around a parasitic hexagonal patch at intervals of 120 degrees. The feed element is selected by the switching device to switch the radiation pattern. This antenna allows for reduction in the number of elements as well as downsizing. The front to back ratio (F/B) becomes 23 dB by selecting suitable parameters.

According to the proliferation of ubiquitous computing, various products which contain large-size embedded software have been developed. One of most typical features of embedded software is concurrency of software and hardware factors. That is, software has connected deeply into hardware devices. The existence of various hardware make quality assurance of embedded software more difficult. In order to assure quality of embedded software more effectively, this paper discusses features of embedded software and an effective method for quality assurance for embedded software. In this paper, we first analyze a failure distribution of embedded software and discuss the effects of hardware devices on quality of embedded software. Currently, in order to reduce hardware related faults, huge effort for testing with large number of test items is required. Thus, one of the most important issues for quality assurance of embedded software is how to reduce the cost and effort of software testing. Next, focusing on hardware constraints as well as software specifications in embedded software, we propose an evaluation metrics for determinating important functions for quality of embedded software. Furthermore, by referring to the metrics, undesirable behaviors of important functions are identified as root nodes of fault tree analysis. From the result of case study applying the proposed method to actual project data, we confirmed that test items considering the property of embedded software are constructed. We also confirmed that the constructed test items are appropriate to detect hardware related faults in embedded systems.

An even-harmonic mixer using a bipolar differential pair (bipolar harmonic mixer;BHMIX) is theoretically analyzed from the direct conversion point of view; i.e, conversion gain, third-order input intercept point (IIP3), self-mixing induced dc offset level, and second-order input intercept point (IIP2). Also, noise are analyzed based on nonlinear large-signal model, and numerical results are given. Noises are treated as cyclostationary noises, thus all the folding effects are taken into account. Factors determining IIP3, IIP2, dc offset, and noise are identified and estimation procedures for these characteristics are obtained. For example, design guidelines for the optimal noise performance are given. Measured results support all the analysis results, and they are very useful in the practical BHMIX design.

This paper gives an efficient algorithm to compute addition in Jacobian of C34 curves, aiming at C34 curve cryptosystems. Using C34 curves for cryptosystems has two advantages. The first is safety and the second is the short size of the base field. In the paper, we modify the addition algorithm of for Cab curves in the specific manner to C34 curves. We classify all of the forms of the Groebner bases of ideals involved in the algorithm and eliminate the use of Buchberger algorithm from it. Our resulting algorithm computes the addition in Jacobian of C34 curves in about 3 times amount of computation of the one in elliptic curves, when the sizes of groups are set to be the same.

The recent sight system requires high stabilization functions for the longer range of observation and the higher kill probability. To this end, it is necessary to compensate rotational disturbances which are not stabilized with the conventional 2-axes stabilization system. This paper proposes a simple method on the rotational motion estimation for the stabilization of the sight system.

This paper presents a technique for designing a dielectric Electronically Steerable Parasitic Array Radiator (Espar) antenna to achieve miniaturization of the conventional Espar antenna. The antenna's size is reduced by immersing the central active element in a dielectric cylinder, mounting the surrounding planar parasitic elements at the circumference of the cylinder, and decreasing the radius of the ground skirt to that of the parasitic elements. An example of a polycarbonate (εr = 2.9 + j0.006) Espar antenna operating at 2.484 GHz is optimised by using a genetic algorithm in conjunction with an FEM-based cost function. The designed antenna generates a half-power beam width of 78and a main lobe that elevates at an angle of only 5from the horizontal plane. The designed antenna is also fabricated and measured. Good agreement between the measurement and simulation results is obtained. We reduce the size of the designed Espar antenna to 1/8 the size of its conventional counterpart while achieving a 12improvement in half-power beam width.

This paper describes a new interface for a barge-in free spoken dialogue system combining an adaptive sound field control and a microphone array. In order to actualize robustness against the change of transfer functions due to the various interferences, the barge-in free spoken dialogue system which uses sound field control and a microphone array has been proposed by one of the authors. However, this method cannot follow the change of transfer functions because the method consists of fixed filters. To solve the problem, we introduce a new adaptive sound field control that follows the change of transfer functions.

This paper presents a distributed task assignment algorithm in a logical unidirectional ring, which guarantees that almost all tasks are assigned to servers with the first come first served (FCFS) policy without a global clock. A task assignment for a process is obtained in the time period needed for a message to circle the ring. This time period is almost optimal for a unidirectional ring. The FCFS policy is very important in terms of task fairness and can also avoid starvation and provide an efficient response time. Simulation results show that the algorithm generally works better than conventional task assignment or load balancing schemes with respect to both mean response time and task fairness.

We proposed 3D-mesh watermarking using CEGI distribution that has robustness against mesh simplification, cropping, vertex randomization, and rotation and which does not need the original model for detection the watermark. The proposed algorithm embeds the watermark bits into the normal vector direction of meshes that are mapped into the cells that have the large magnitude of complex weight in patch CEGIs. The watermark can be detected based on the known center point of each patch and the rank table of the cell in each patch instead of original model. Experimental results verified that the proposed algorithm has robustness against the attacks.

This paper presents analysis results on finite-impulse response (FIR) channel estimation used for the equalization in Advanced Television Systems Committee digital television receivers. While channel estimation results have been effectively used for the equalization, the conditions of sufficient order and high signal-to-noise ratio (SNR) were assumed in most cases. To compensate for these unrealistic assumptions, we consider diverse probable conditions for channel estimation, such as reduced order and low SNRs, and then theoretically analyze each estimation case. The analysis shows that the adaptive FIR channel estimator provides an unbiased estimation and matches well its corresponding channel coefficients irrespective of the number of taps of the estimator and the non-causality of the unknown channel. Simulation results verify our analysis on the estimation of terrestrial DTV channels.

In this paper, the throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences which combines the ALOHA system with Code Shift Keying using nonorthogonal sequences is analyzed. In this system, the nonorthogonal sequences are constructed by concatenating Mcon orthogonal sequences. The throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences is analyzed in consideration that the number of packets changes at intervals of one orthogonal sequence. Moreover, the throughput performance of our system with Channel Load Sensing Protocol (CLSP) is also analyzed. We also examine the influence of unreachable control signal of CLSP. Consequently, it is found that the throughput performance of our system decreases significantly by this analysis. It is also found that the throughput performance of our system improves greatly by using CLSP. However, the unreachable control signal affects the throughput performance of this system, seriously.

Fundamentals of parametric processing in highly nonlinear optical fiber are reviewed. Experimental procedures necessary for construction of one- and two-pump parametric amplifier architectures are described. Pump phase broadening, dispersion fluctuation and birefringence form basic impairment mechanisms in fiber parametric devices and are analyzed in two-pump parametric devices. Parametric signal processing is introduced with specific applications in all-optical regeneration, band conjugation, multicasting, packet switching and signal distortion reversal.

For wavelength conversion based on cross-gain modulation (XGM) and cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), a CW assist light is quite effective for acceleration of carrier recovery and reduction of pattern effects. We theoretically study assist light conditions both for XGM- and XPM-based wavelength conversion by numerically simulating eye-diagrams. Taking into account the spatial and temporal variations of carrier density along the SOA length, we successfully clarify the dependences of wavelength, power, and propagation direction of the assist light, and reveal the principal difference of response characteristics between XGM and XPM depending on carrier modulation.

It is important to look for alternative forms of physical movement of people and equipments in order to assure diagnosis and maintenance tasks, especially in an environment where workers are subject to danger. An evident and classical solution is the use of the tele-operation and tele-robotics. If the tele-operation helps to solve a lot of real and technical problems, it still remains insufficient to assure an appropriate remote diagnosis and maintenance. The use of virtual reality techniques with the tele-operation can be the solution for an effective remote maintenance and diagnosis. In this paper we show the inefficiency occurred with the use of only tele-operation in the remote maintenance, we introduce our original new system where we use virtual reality techniques and 2D-3D matching (2D camera image-3D virtual objects) with tele-operation to remotely collect machinery vibration data. We explain its structure, implementation and its advantages. We finished by experimenting the system, measuring the different operating times and precision and discuss the results.

We show that the necessary and sufficient condition for the existence of a balanced C4-bowtie decomposition of the complete multi-graph λKn is λ(n - 1) 0 (mod 16) and n 7. Decomposition algorithms are also given.

We propose a unified view to deal with two formulations of image distortion and a method for estimating the distortion parameters for both of the formulations; So far the formulations have been developed separately. The proposed method is based on image registration and consists of nonlinear optimization to estimate parameters including view change and radial distortion. Experimental results demonstrate that our approach can deal with the two formulations simultaneously.

Photonic crystal fiber (PCF) is a promising candidate for future transmission media due to its unobtainable features in a conventional single-mode fiber. We discuss some important problems to realize a PCF for transmission purpose. We also present recent progress on the PCF as a transmission media.

Micro/picocellular architectures for wireless networks have been proposed to provide higher capacity under limited radio spectrum. With smaller cell size, the frequency of hand-off events will increase. This will in turn increase the overheads for processing hand-off events. To reduce the overheads due to frequent hand-off, a cell-cluster concept has been proposed in [1]. In this paper, we propose a call admission control policy for cluster-based micro/picocellular wireless networks, that employs two levels of admission thresholds: one at the cell level and the other at the cluster level. An analytical method is developed to analyze the performance of the proposed policy. The analytical method is then applied to find the values of the admission thresholds such that the throughput of the network is maximized under the condition that a predetermined bound on the call hand-off dropping probability is guaranteed. Compared with call admission policies that employ a single threshold either at the cell level or at the cluster level under the condition that the policies provide the same predetermined maximum level of call hand-off dropping probability, the proposed call admission policy provides significantly better performance.