Traveling electromagnetic waves on infinite linear periodic arrays of lossless penetrable spheres can be conveniently analyzed using the source scattering-matrix framework and vector spherical wave functions. It is assumed that either the spheres are sufficiently small, or the frequency such, that the sphere scattering can be treated using only electric and magnetic dipole vector spherical waves, the electric and magnetic dipoles being orthogonal to each other and to the array axis. The analysis simplifies because there is no cross-coupling of the modes in the scattering matrix equations. However, the electric and magnetic dipoles in the array are coupled through the fields scattered by the spheres. The assumption that a dipolar traveling wave along the array axis can be supported by the array of spheres yields a pair of equations for determining the traveling wave propagation constant as a function of the sphere size, inter-sphere separation distance, the sphere permittivity and permeability, and the free-space wave number. These equations are obtained by equating the electric (magnetic) field incident on any sphere of the array with the sum of the electric (magnetic) fields scattered from all the other spheres in the array. Both equations include a parameter equal to the ratio of the unknown normalized coefficients of the electric and magnetic dipole fields. By eliminating this parameter between the two equations, a single transcendental equation is obtained that can be easily solved numerically for the traveling wave propagation constant. Plots of the k - β diagram for different types and sizes of spheres are shown. Interestingly, for certain spheres and separations it is possible to have multiple traveling waves supported by the array. Backward traveling waves are also shown to exist in narrow frequency bands for arrays of spheres with suitable permittivity and permeability.

In order to achieve omni-directional coverages on base station antennas for fixed wireless access systems (FWA), a TM01 mode conical horn with 4.6λ aperture size was employed as a feed horn for an axisymmetrical reflector antenna. Here, a shaped dielectric lens was inserted in the conical horn so as to achieve low sidelobe radiation characteristics. However, it was pointed out that radiation pattern shaping ability was degraded in this small lens antenna. In this paper, deteriorations of aperture distributions in a shaped lens are clarified through FDTD calculations. Severe phase delays are shown in the aperture phase distributions. A novel lens shaping method of compensating the phase delays is developed. Aperture distributions and radiation patterns of the corrected lens are estimated through FDTD calculations. Satisfactory uniform phase distributions in aperture distributions and low sidelobe radiation patterns are ensured.

This paper introduces the design procedure of the contrived network TV broadcasting transcoder/encoder system, especially develops a new variable bit-rate (VBR) coding bit allocation strategy with a constraint channel bandwidth and consistent picture quality for multiple parallel video sequences broadcasting, which accommodates the complicated video sources with different frame rates and GOP structures, and combines the buffer control and the optimized macroblock (MB) coding mode selection. The proposed strategy absorbs several reasonable metrics in a hierarchical structure, and provides flexibility and promotion for resource allocation in multi-access scenario. Experimental results demonstrate the effect of the proposed scheme.

This paper presents an analysis of the Slotted DS-CDMA system with modified node components in order to construct a load control structure in which the service rates of each node can be dynamically adapted without using feedback information. In contrast to the traditional Slotted DS-CDMA which is widely represented with single queue, prior emphasis of the approach is laid on the usage of an additional queue which is applied to manage the collided packet traffic while its queue size is also used as a load control parameter. Semi-Markov process is applied to describe the statistic behavior of the system in steady state. Trade-offs between two major performance parameters, i.e., delay and throughput, are presented and compared with those of the traditional system. Results obtained from the simulation and numerical analysis using queuing concept are compared. With these results, an advantage performance for group packets is shown, and we finally extend the concept based on the obtained results to describe a simple algorithm using one way control message as the tool to alleviate the stability problem.

An asymmetric Dual Metal Stack Gate (DMSG) SOI MOSFET transistor has been investigated for its enhanced electrical characteristics. A 2-D physical model has been proposed and its results have been confirmed by those obtained by simulation. These results predict better short channel effects such as drain induced barrier lowering (DIBL) characteristics and hot carrier effects for this device compared to those for conventional SOI MOSFETs. The effects of the Stacked Gate (SG) and Dual Metal Gate (DMG) structures on short channel effects are compared. It has been observed that SG reduces DIBL significantly, while DMG prevents the normal roll-off of the threshold voltage reduction.

We have launched "Highly-Reliable Embedded Software Development" Project, held as a part of e-Society Project, supported by Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The aim of this project is to enable the industry to produce highly reliable and advanced software by introducing latest software technologies into embedded software development. In this paper, we introduce the overview of the projects and our activities and results so far.

A sub-grid finite-difference time-domain (FDTD) method was applied to analyze electromagnetic (EM) interaction between a 5 GH band antenna mounted laptop personal computer (PC) and a human body model in realistic use situations. The investigated situations were a typing and a non-typing PC users, who were simulated with a realistic whole body or half body model. It was found that the body proximity effect was mainly blocking the radiation up to 20 dB towards the body side, and the hands on the keyboard were mainly blocking the radiation up to 10 dB towards the direction at an angle to the head. It was also found that the highest EM absorption in the typing and non-typing situations occurred in the hand and in the chest, respectively, and the hands on the keyboard had a significantly blocking effect for the SAR spread to the head region. The peak SAR levels were low enough compared to the safety guidelines.

A structure of a track-and-hold (T/H) circuit based on a pair of complementary floating-gate (FG) MOS transistors is introduced. Its main features include low complexity, low operating supply voltage and gain insensitivity to device mismatches, leading to efficient realization of numerous baseband functions in modern communication systems. The detailed operation and performance analysis of the FG T/H circuit are given. Functional verification of the circuit is provided through a breadboard experiment. The effectiveness of the circuit is verified via simulations where the single T/H cell operating at 10 MHz clock frequency exhibits gain variation less than 0.13% and a dynamic range over 71 dB with the coupling capacitance of 300 fF at 1.5 V supply and 12.75 µW power consumption. As a demonstration on its practical viability, the designed FG T/H cell was also utilized to realize a 10 MS/s 7-tap analog correlator for possible use in modern communication applications.

In QoS routing, load balancing routing algorithm for long-lived traffic can be used efficiently to minimize the number of routing update, control traffic overhead and computational overhead which mainly come from network traffic fluctuation. The congestion problem from short-lived traffic is however difficult to handle. A simple and robust algorithm is needed for short-lived traffic to reduce the traffic loss probability. In the paper, we proposed a new hybrid routing schemes for short-lived traffic and long-lived traffic. An alternate routing algorithm is applied for the short-lived traffic when congestion occurs. We restricted the number of additional hops in the path to minimize the negative effect of alternate routing algorithm. The proposed algorithm reduces packet loss probability from 0.6% to 1.7% under various link utilizations. We also compare our proposed algorithms with and without crank-back.

A new approach is proposed in this paper for the tracking of the optimal operating frequency in a Class E backlight inverter using the phase-locked loop (PLL) technique. First, a new single-stage backlight module is introduced to simplify the circuit and to raise the system efficiency. A piezoelectric transformer (PT) is used to drive the cold cathode fluorescent lamp (CCFL) to eliminate the downside of a conventional transformer and to reduce the dimension of the backlight module. Next, a PLL is embedded in the backlight system, as a feedback mechanism, to track the optimal operating frequency of the PT so that the PT's temperature effect is removed and, hence, the system efficiency and stability is improved. The feedback variable proposed is a phase angle rather than a lamp current amplitude traditionally used. A simplified model, along with its design procedure, is next presented. The complete analysis and design considerations are detailed. Finally, it is rather encouraging to observe that the experimental results match our analytical solutions closely.

A series-fed beam-scanning array employing a MUlti-Stage Configured microstrip Antenna with Tunable reactance devices (MUSCAT) is proposed. The proposed antenna significantly expands the beam scanning range and achieves high efficiency. This antenna comprises unit element groups, whose elements are placed close to each other and employ tunable reactance devices. Analyses and experiments on the unit element groups show that their multi-stage configuration extends the phase shift range and increases the radiation efficiency, e.g., a 120phase shift and the radiation efficiency of more than 50% are achieved, when three stages are employed. The radiation pattern of the fabricated MUSCAT array antenna comprising eight unit element groups is measured. A beam scanning range of 27, which is greater than twice the beam scanning range of a non-multi-stage configuration, is achieved.

This paper describes the contours of a Dutch monitoring and research site for climate change and related atmospheric processes. The station has large benefits for atmospheric science, both in The Netherlands and internationally. It provides a platform for collaboration in this important field, and will provide the routine observations needed to assess the impact of the different atmospheric parameters on the local climate. The station fits in directly in the selected group of global monitoring networks that are currently operational or being set up to address the problems of climate. In addition, the station can play a major role in supporting worldwide satellite measurements of climate related parameters. The only way to get a global picture of the essential climate change parameters can be found in the combination of satellite measurements and ground-based stations equipped with advanced remote sensing and in situ instrumentation. Furthermore, the combined expertise of European universities and research institutes, encompassing the whole field of atmospheric research, offers a unique chance for the training of young scientists. The research site is an attractive center for international young scientists to develop and deepen their skills.

The rain attenuation in the 12-GHz band and one-minute-rain rate were measured in Tokyo over a four-year period (2000-2003). The statistical characteristics of this data are presented. The one-minute-rain rates at 0.01% of time percentage of year in Tokyo and Osaka are compared to other past and recent values. The comparison of measured rain attenuation in the 12-GHz band in Tokyo and Osaka with prediction by ITU-R methods is conducted. The root-mean-square prediction error of rain attenuation for the prediction by ITU-R Rec.P.618 is evaluated. Convective rain cell effects can be seen in the scatter diagram of one-minute-rain rate and rain attenuation. However, it is found that the effect is not properly accounted for by the slant path length adjustment factor of P.618-8. A reliable rain attenuation prediction requires some revisions of the slant path length adjustment factor with taking local weather characteristics into account for the P.618-8.

Larger object classes often become more costly classes in the maintenance phase of object-oriented software. Consequently class would have to be constructed in a medium or small size. In order to discuss such desirable size, this paper proposes a simple method for predictively discriminating costly classes in version-upgrades, using a class size metric, Stmts. Concretely, a threshold value of class size (in Stmts) is provided through empirical studies using many Java classes. The threshold value succeeded as a predictive discriminator for about 73% of the sample Java classes.

It is not always possible to find a global parse for an input sentence owing to problems such as errors of a sentence, incompleteness of lexicon and grammar. Partial parsing is an alternative approach to respond to these problems. Partial parsing techniques try to recover syntactic information efficiently and reliably by sacrificing completeness and depth of analysis. One of the difficulties in partial parsing is how the grammar might be automatically extracted. In this paper we present a method of automatically extracting partial parsing rules from a tree-annotated corpus using the decision tree method. Our goal is deterministic global parsing using partial parsing rules, in other words, to extract partial parsing rules with higher accuracy and broader expansion. First, we define a rule template that enables to learn a subtree for a given substring, so that the resultant rules can be more specific and stricter to apply. Second, rule candidates extracted from a training corpus are enriched with contextual and lexical information using the decision tree method and verified through cross-validation. Last, we underspecify non-deterministic rules by merging substructures with ambiguity in those rules. The learned grammar is similar to phrase structure grammar with contextual and lexical information, but allows building structures of depth one or more. Thanks to automatic learning, the partial parsing rules can be consistent and domain-independent. Partial parsing with this grammar processes an input sentence deterministically using longest-match heuristics, and recursively applies rules to an input sentence. The experiments showed that the partial parser using automatically extracted rules is not only accurate and efficient but also achieves reasonable coverage for Korean.

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.

We propose a modified Hidden Markov Model (HMM) with a view to improve gesture recognition using a moving camera. The conventional HMM is formulated so as to deal with only one feature candidate per frame. However, for a mobile robot, the background and the lighting conditions are always changing, and the feature extraction problem becomes difficult. It is almost impossible to extract a reliable feature vector under such conditions. In this paper, we define a new gesture recognition framework in which multiple candidates of feature vectors are generated with confidence measures and the HMM is extended to deal with these multiple feature vectors. Experimental results comparing the proposed system with feature vectors based on DCT and the method of selecting only one candidate feature point verifies the effectiveness of the proposed technique.

This study presents a method of realizing second order band-pass filters with planar inductive π-network. The proposed filter is more flexible in practical implementation than those using magnetic or electric coupling methods. Electromagnetic simulation results show that the bandwidth of the filter is quite insensitive to the variation in substrate thicknesses and physical layout. A 5.2 GHz filter prototype is designed and fabricated. The measured insertion loss is less than 2.3 dB in the designed pass band and the attenuations at the stop bands are all greater than 30 dB.

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.

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.