In this paper, we propose an interactive instruction system named IMPRESSION, which allows performance of interactive presentations using multimedia educational materials in class. In recent years, although many practices of educational methodology with information technology and presentation tools using multimedia resources as educational materials have come into common use, instructors can only present such materials in a slide-sheet form through the use of such presentation tools in class. Therefore, instructors can neither do formative evaluations nor can they present suitable materials according to students' reactions in class. Our proposed methodology employs a scenario-based approach in a double loop instructional design process to overcome such problems. Instructors design an instructional plan as a scenario, and subsequently implement and modify the plan through formative evaluation during the class. They then conduct a summative evaluation based on planned and implemented instructions for redesign. To realize our methodology, in this paper we propose and design an instruction system that provides functions to select and present multimedia materials interactively provided on the Internet during the class; we then record these instructions. After implementing it, we confirmed that we can conduct the class flexibly based on our methodology through its practical use in an actual classroom environment.

In this paper, a new dimming algorithm for the electronic ballast of an electrodeless fluorescent lamp is proposed. The proposed method is based on the burst dimming method that controls the duty ratio for the two switches of the electronic ballast by intermittently modulated pulse signal. This paper presents a fully digital circuit using an erasable programmable logic device (EPLD). To verify the validity of the proposed method, the implemented control circuit was applied to the electronic ballast for a 100 W electrodeless fluorescent lamp. As a result, a dimming method with a wide illumination range from 5 to 100% was obtained.

The concept of M-convex functions has recently been generalized for functions defined on constant-parity jump systems. The b-matching problem and its generalization provide canonical examples of M-convex functions on jump systems. In this paper, we propose a steepest descent algorithm for minimizing an M-convex function on a constant-parity jump system.

This paper proposes a Weil descent attack against elliptic curve cryptosystems over quartic extension fields. The scenario of the attack is as follows: First, one reduces a DLP on a Weierstrass form over the quartic extention of a finite field k to a DLP on a special form, called Scholten form, over the same field. Second, one reduces the DLP on the Scholten form to a DLP on a genus two hyperelliptic curve over the quadratic extension of k. Then, one reduces the DLP on the hyperelliptic curve to one on a Cab model over k. Finally, one obtains the discrete-log of original DLP by applying the Gaudry method to the DLP on the Cab model. In order to carry out the scenario, this paper shows that many of elliptic curve discrete-log problems over quartic extension fields of odd characteristics are reduced to genus two hyperelliptic curve discrete-log problems over quadratic extension fields, and that almost all of the genus two hyperelliptic curve discrete-log problems over quadratic extension fields of odd characteristics come under Weil descent attack. This means that many of elliptic curve cryptosystems over quartic extension fields of odd characteristics can be attacked uniformly.

The characteristics of various techniques, including some new techniques, in mitigating wavelength contention in optical path setups were compared by simulations. The assumed network here is a WDM photonic network in which each node is equipped with a limited number of wavelength-tunable optical transceivers. In the photonic network, the frequency of optical path setups and releases is very high, because optical path lifetime is short and optical transceivers are time-shared, and therefore, the wavelength contention becomes a serious problem. In this paper, we propose four new techniques to mitigate the phenomenon. In those techniques, a new small-sized parameter, the history number, was introduced based on the conceptual requirements of the assumed network, namely, low-cost and low additional control load. The four proposed techniques are history recording (HR), history notifying (HN), conditional random selection (CRS), and HN with dithering target (HNDT). We have evaluated the characteristics of those techniques along with those of two conventional techniques: no mitigation and random selection (RS). The simulations were carried out while varying four parameters: the maximum generation number, the optical path lifetime, the number of wavelengths, and the number of optical transceivers per node. Consequently, it is clarified that for a sufficient number of wavelengths, namely, almost no limitation on number of wavelengths, the CRS technique is advantageous, and for a small number of wavelengths the HNDT technique is advantageous.

Scenarios that describe concrete situations of software operation play an important role in software development, especially in requirements engineering. Since scenarios are informal, the correctness of scenarios is hard to be verified. The authors have developed a language for describing scenarios in which simple action traces are embellished. The purposes are to include typed frames based on a simple case grammar of actions and to describe the sequence among events. Based on this scenario language, this paper describes both (1) a correctness-checking method using rules to detect errors (lack of events, extra events, and wrong sequence among events) in a scenario and (2) a retrieval method of rules from rule DB that applicable to scenarios using pre and post- conditions.

In this paper, a novel projection-based method is presented to register partial 3D point clouds, acquired from a multi-view camera, for 3D reconstruction of an indoor scene. In general, conventional registration methods for partial 3D point clouds require a high computational complexity and much time for registration. Moreover, these methods are not robust for 3D point cloud which has a low precision. To overcome these drawbacks, a projection-based registration method is proposed. Firstly, depth images are refined based on both temporal and spatial properties. The former involves excluding 3D points with large variation, and the latter fills up holes referring to four neighboring 3D points, respectively. Secondly, 3D point clouds acquired from two views are projected onto the same image plane, and two-step integer mapping is applied to search for correspondences through the modified KLT. Then, fine registration is carried out by minimizing distance errors based on adaptive search range. Finally, we calculate a final color referring to the colors of corresponding points and reconstruct an indoor scene by applying the above procedure to consecutive scenes. The proposed method not only reduces computational complexity by searching for correspondences on a 2D image plane, but also enables effective registration even for 3D points which have a low precision. Furthermore, only a few color and depth images are needed to reconstruct an indoor scene. The generated model can be adopted for interaction with as well as navigation in a virtual environment.

A new technique incorporating combinatorial deposition to develop thin-film phosphors by r.f. magnetron sputtering is demonstrated using subdivided powder targets. In comparison with development using conventional r.f. magnetron sputtering, the atomic ratios of Si and Ge as well as the Mn content in Zn2Si1-XGeXO4:Mn thin film phosphors could be more efficiently optimized in order to obtain the highest intensity in electroluminescent and photoluminescent emissions. High luminances of 11800 and 1536 cd/m2 were obtained in Zn2Si0.6Ge0.4O4:Mn thin-film electroluminescent devices fabricated under optimized conditions and driven at 1 kHz and 60 Hz, respectively.

In search of suitable white-LED for general illumination, we fabricated various types of white-LEDs using different methods. As the first method, we used the multichip method in which multiple emitters were mounted in one package. This type showed a good general color-rendering index (Ra) = 90 by the optimizing the emission wavelength of each LED chip. However, the electric driving circuitry was too complex for use in general illumination. Secondly, we used a monolithic white-LED by using the multicolor emitting multiple-quantum well (MQW) for the active layers, which consisted of quantum wells (QWs) with different In compositions. A high Ra = 80.1 was obtained in the three-color-emitting white-LED but the luminous efficacy (ηL) was only 8.11 lm/W. As the third method, we used the color conversion method using phosphors. We fabricated a white-LED which consisted of a near-UV-LED chip and blue/yellow phosphors in order to improve the luminous efficacy of the white-LED under high forward-bias current. At 100 mA, the luminous flux (IL) was estimated to be 7.6 lm. However, this white-LED degraded quickly, because the epoxy resin used for package was the general purpose one and deteriorated under the UV-light from the n-UV-LED. Next, we improved the Ra and ηL of a traditional white-LED which consisted of blue-LED chip and yellow phosphor. In order to improve the Ra, we added a newly developed red phosphor. We obtained a Ra = 87.7 at low-color-temperature. Then, in order to improve the efficiency of the white-LED, we improved the extraction efficiency (ηEX) of the blue-LED by using a patterned sapphire substrate and a high reflection Rh-mesh-patterned p-electrode. Then, we obtained a 62.0 lm/W at 20 mA. As a result, we concluded that the color conversion method of using a blue-LED for general illumination has advantages in efficiency, color-rendering, cost and lifetime. It also has simpler electric driving circuitry.

The four-septum transverse electromagnetic (TEM) cell is like the traditional TEM cell but has four plate-like septa in the internal space. A slowly rotating field can be easily generated in the four-septum TEM cell, thus radiated immunity/susceptibility characteristics of an EUT under arbitrary specific polarizations can be measured without rearranging the test setup. A design approach for the four-septum TEM cell is discussed in this paper. The characteristics of the cell are analyzed based on the telegrapher's equation and decomposition of the transmission mode into four independent modes. Then a design approach is given based on the analytical results. A prototype of the four-septum TEM cell based on the design is constructed and the characteristics of the prototype cell are experimentally evaluated. The validity and effectiveness of the design approach are confirmed.

A new generation method of rotating electromagnetic fields (rotating-EM fields) for radio frequency (RF) radiated immunity/susceptibility test and its basic characteristics are described. Two different double-side-band suppressed-carrier (DSB-SC) signals are required for generating the slowly rotating-EM field for the immunity/susceptibility test. These DSB-SC signals are generated by a DSB-SC-signal generator based on the new concept which consists of voltage-variable attenuators, bi-phase switches, a direct-digital synthesizer and a micro processor. Using the DSB-SC-signal generator, the DSB-SC signal of arbitrary RF frequency can be generated more easily than the conventional system. In this paper, the principle of the DSB-SC signal generator and the basic characteristics of the DSB-SC signals generated by the generator are clarified. The measured basic characteristics of the rotating-EM field generated using the new concept are shown and it is confirmed that the field can be applied for the RF immunity/susceptibility test. In addition, the susceptibility test of an equipment under test is made as an example, the validity of our proposed system is established.

We calculated the shielding characteristic of a three-dimensional array of strip conductors by using the electric field integral equation method and its expansion to an array structure. From reflection coefficients, the effective permittivity of the array is calculated. The effective permittivity becomes negative in the frequency range above resonance, in which the electromagnetic waves travel through the material in an evanescent mode and the transmission coefficient becomes very small.

This CMOS transceiver IC exploits the superheterodyne architecture to implement a low-cost RF front-end with only 6.25 mm2 die area for IEEE 802.11b standard. The transceiver is implemented in 0.25 µm CMOS process with 2.7 V supply voltage, and achieves a -86 dBm 11 Mb/s receive sensitivity and a 2 dBm transmit output power.

An on-package dual-mode square-loop band pass filter is studied by applying a non-uniform finite difference time domain (NU-FDTD) method. The filter is integrated on a package containing a transceiver, and it is designed to operate in dual-modes, i.e., and , to ensure a good electric performance around the center frequency at 5.25 GHz, which is commonly allocated in wireless local area network (WLAN). This filter is also referred as a dual-mode integrated-circuit package filter (DM-ICPF) based on its operational mode and integration onto an IC-package. The frequency characteristics in terms of the scattering parameters are studied, and the results are validated against the computed results using commercial software, the high frequency structure simulator (HFSS). Results show an excellent agreement between the numerical data, and the proposed DM-ICPF structure can be applied in the area of the highly integrated wireless transceivers.

The discovery of the Turbo codes has driven research on the creation of new signal detection concepts that are, in general, referred to as the Turbo approach. Recently, this approach has made a drastic change in creating signal detection techniques and algorithms such as equalization of inter-symbol interference (ISI) experienced by broadband single carrier signaling over mobile radio channels. A goal of this paper is to provide readers with broad views and knowledge of the Turbo concept-based Multiple-Input Multiple-Output (MIMO) signal transmission techniques. How the techniques have been developed in various applications and how they perform in real-field environments are introduced.

This paper presents an overview of four on-going European research projects in the field of mobile and wireless communications leading to the next generations of wireless communications. The projects started in 2004. They investigate requirements and definition of access technology, network architecture, antennas and propagation, security, services, applications and socio-economic impact.

The abstract ray-tracing problem asks, for a given scene consisting of a light source, a light receiver and finitely many obstacles in a space, and a given positive integer ε > 0, whether a ray going out from the light source could reach the light receiver with intensity at least ε. The problem is known to be PSPACE-hard, and it is very unlikely that there exists an efficient algorithm to solve the problem without adding any restriction. In this paper, we show that the problem can be solved in polynomial time under some weak practical restrictions.

Hypersequential programming is a new method of concurrent-program development in which the original concurrent program is first serialized, then tested and debugged as a set of sequential programs (scenarios), and finally restored into the target concurrent program by parallelization. Both high productivity and reliability are achieved by hypersequential programming because testing and debugging are done for the serialized versions and the correctness of the serialized programs is preserved during the subsequent parallelization. This paper proposes scenario-based hypersequential programming for reactive multitasking systems that have not only concurrency and nondeterminacy, but also interruption and priority. Petri nets with priority are used to model reactive systems featuring interruption and priority-based scheduling. How reactive systems are made highly reliable by this approach is explained and the effectiveness of the approach is demonstrated through the example of a telephone terminal control program.

In this report, we propose a tracking algorithm of speaker direction using microphones located at vertices of an equilateral triangle. The method realizes tracking by minimizing a performance index that consists of the cross spectra at three different microphone pairs in the triangular array. We adopt the steepest descent method to minimize it, and for guaranteeing global convergence to the correct direction with high accuracy, we alter the performance index during the adaptation depending on the convergence state. Through some computer simulation and experiments in a real acoustic environment, we show the effectiveness of the proposed method.

Integrated 900-MHz ISM band transceiver LSI for analog cordless telephone has been realized by cost-effective process technology with sufficient performance. This LSI consisted of fully integrated transceiver, from RF-LNA to audio amplifier for RX chain, from microphone's amplifier to RF-PA for TX chain, and integrated RX- and TX-LO consisting of PLLs and VCOs. In view of narrow signal bandwidth with analog modulation, extremely low phase noise at low offset frequency from carrier was required for integrated VCO. Also, in view of fully duplex operations, signal isolation between TX and RX was required. Despite such a high integration and high performance, chip cost had to be minimized for low-cost applications. The 12-dB SINAD RX sensitivity was -111.2 dBm, the output power of TX was +3 dBm, and the phase noise of integrated VCO was -77 dBc/Hz at 3 kHz offset away from carrier. The current consumption at fully duplex operation was 76 mA at 3.6 V power supply. The chip was realized by 0.8 µm standard silicon BiCMOS process.