Ultra wideband (UWB) radar cross sections (RCSs) of several targets have been measured using various combinations of transmitting and receiving linear polarizations (V-V, H-H, and +45- -45) with a view to obtaining information on the design of vehicular short-range radars. This paper reports the UWB RCSs (σLR and σLL) of a typical passenger automobile using two circular polarization combinations (L and R denote left and right circular polarizations). The wideband measurements were carried out with use of a vector network analyzer by sweeping the frequency from 24.5 to 28.8 GHz in a radio anechoic chamber. The UWB RCSs were derived by integrating the received power in the frequency domain. Similar to the linear polarization results, fluctuations of the RCSs were smaller in the UWB than in narrowband for both L-R and L-L, because the ultra-wide bandwidth cancels out RCS plunges caused by narrowband interference among reflected waves from various facets of the target. The median of (σLR- σLL) was 2 dB, while the median of (σHH - σ+45 - -45) or (σVV-σ+45- -45) was 6 dB. This is because the body of the automobile comprises a number of smaller scattering objects yielding σ LL, either similar to the corner reflectors or asymmetrical to the radar boresight. Frequency-domain responses showed a number of notches caused by the interference between numerous reflecting waves having power levels of a similar order and different round-trip path lengths. Some representative reflective parts of the automobile were identified through analyses of time-domain responses.

A new paradigm in the design of optical coatings connected with an outstanding computational efficiency of modern design techniques is discussed. Several other topics including pre-production error analysis, monitoring of coating production, and computational manufacturing of optical coatings are considered.

Optical anisotropy was induced in azobenzene copolymer film using linearly or elliptically polarized laser beams. The Jones matrix of the anisotropic film was calculated from the change in polarization of the probe light. Two eigenpolarization states were obtained from the matrix. These two eigenstates are useful as a polarization basis for a polarization-tunable component.

We developed new principle of electronic paper that is one side (for 2D image) or double side (for stereoscopic 3D image) light printable rewritable matter with polarization dependent gray scale. It consists of one or two liquid crystal displays based on Optical Rewritable (ORW) technology, which is the development of rotation azo-dye photoalignment. Each ORW display uses bare plastic or polarizers as substrates. The conductor is not required, as the image is formed by rewritable states of azimuthal direction, which results in 2D pattern of the liquid crystal twist angle. Continuous grey image maintains proper performance even when the device is bent. Simple construction provides durability and low cost, thin substrates minimize parallax for 3D image. Fluorescent dye dopant of liquid crystal partly absorbs light in blue and re-emit in green specter range improving photopic reflection and enhancing color of the ORW e-paper.

This letter presents an efficient adaptive beamformer to deal with the multipath environments created by signal source scatterings. To improve the performance possible with the fixed forgetting factor, the regular adaptive forgetting factor algorithm is derived and applied to the subarray recursive least squares (RLS) beamforming. Simulations confirm that the proposed scheme has better performance than not only the conventional RLS algorithm but also the subarray RLS and adaptive forgetting factor RLS algorithms.

Ga-doped ZnO thin films were prepared by RF magnetron sputtering. The effects of adding H2 to pure Ar sputtering gas were investigated. In the case of pure Ar at 2 Pa, the resistivity is 7.4510-3 Ωcm, whereas for Ar+1%H2 at 0.3 Pa, it markedly decreases to 2.5210-4 Ωcm. In this case, the carrier density and Hall mobility are 1.121021 cm-3 and 23.4 cm2/Vs, respectively. This conductive film also exhibits a transmittance of 90% within the visible-wavelength range. The addition of H2 and the decrease in the pressure results in the fabrication of a significantly more transparent and conductive film.

In the execution on a smart card, elliptic curve cryptosystems have to be secure against side channel attacks such as the simple power analysis (SPA), the differential power analysis (DPA), and the refined power analysis (RPA), and so on. MMM-algorithm proposed by Mamiya, Miyaji, and Morimoto is a scalar multiplication algorithm secure against SPA, DPA, and RPA, which can decrease the computational complexity by increasing the size of a pre-computed table. However, it provides only 4 different cases of pre-computed tables. From the practical point of view, a wider range of time-memory tradeoffs is usually desired. This paper generalizes MMM-algorithm to improve the flexibility of tables as well as the computational complexity. Our improved algorithm is secure, efficient and flexible for the storage size.

This letter proposes a UWB signaling localization scheme for indoor multipath channel. It demonstrates that the proposed method does not require LOS path (LP) and is suitable for severe non line-of-sight (NLOS) condition. A low-complexity TOA estimation algorithm, the strongest path (SP) detection by convolution, is designed, which is easier to implement than the LP detection since it dispenses with the process of threshold setting. Experiments under NLOS channels in IEEE.802.15.4a are conducted and the localization influences due to the algorithm parameters are discussed. The results prove the feasibility of the proposed localization scheme under the indoor multipath NLOS environment.

Focusing on time correlation of real communication channels, a channel quantization algorithm based on finite state vector quantization (FSVQ) is proposed. Firstly channels are partitioned into finite states, then codebooks corresponding to each state are constructed, which are used to quantize channels transferred from corresponding states. Further, the state transition function is designed to ensure the synchronization between transmitter and receiver. The proposed algorithm can achieve improved performance with the same feedback load compared with classical memoryless channel quantizer without consideration of the influence of time correlation. Simulation results verify the effectiveness of the proposed algorithm.

This paper proposes the Gramian-preserving frequency transformation for linear discrete-time state-space systems. In this frequency transformation, we replace each delay element of a discrete-time system with an allpass system that has a balanced realization. This approach can generate transformed systems that have the same controllability/observability Gramians as those of the original system. From this result, we show that the Gramian-preserving frequency transformation gives us transformed systems with different magnitude characteristics, but with the same structural property with respect to the Gramians as that of the original system. This paper also presents a simple method for realization of the Gramian-preserving frequency transformation. This method makes use of the cascaded normalized lattice structure of allpass systems.

This paper performs application-level QoS and user-level QoS assessment of audio-video streaming in cross-layer designed wireless ad hoc networks. In order to achieve high QoS at the user-level, we employ link quality-based routing in the network layer and media synchronization control in the application layer. We adopt three link quality-based routing protocols: OLSR-SS (Signal Strength), AODV-SS, and LQHR (Link Quality-Based Hybrid Routing). OLSR-SS is a proactive routing protocol, while AODV-SS is a reactive one. LQHR is a hybrid protocol, which is a combination of proactive and reactive routing protocols. For application-level QoS assessment, we performed computer simulation with ns-2 where an IEEE 802.11b mesh topology network with 24 nodes was assumed. We also assessed user-level QoS by a subjective experiment with 30 assessors. From the assessment results, we find AODV-SS the best for networks with long inter-node distances, while LQHR outperforms AODV-SS for short inter-node distances. In addition, we also examine characteristics of the three schemes with respect to the application-level QoS in random topology networks.

The properties of the surface-conduction electron-emitter display (SED) are mainly decided by the surface-conduction electron emitters (SCE), which are normally made from the expensive metal Pd. In this study, we propose to use metal Zn instead of Pd as the emitter material. Both the device electrode and ZnO thin film are deposited by a sputter, and the electron emitters (SCE) are formed by the electro-forming process. The electron emission characteristic is obtained and the luminescence is observed.

Rubbed polyimide films have been widely used as liquid crystal alignment films for liquid crystal displays. Washing after rubbing is essential to fabricate liquid crystal displays, and should affect alignment of liquid crystal as well as rubbing. We investigated the effects of rubbing condition and soaking in acetone on polyimide films by grazing incidence X-ray diffraction. It was found that soaking in acetone promoted crystallization of surface aligned polymers, and that the crystallization by acetone was dependent on the initial polymer alignment. The larger initial crystalline phase was, the more newly crystallization occurred by soaking. It was also revealed that the crystallization by soaking in acetone was completed within 1 min.

Two types of thin-film phototransistors (TFPTs), p/i/n TFPT and n/i/n TFPT, are characterized from the viewpoint of operation condition and device behavior. It is found that the detected current can be both independent of the applied voltage (Vapply) and linearly dependent on the photo-illuminance in the saturation region of the p/i/n TFPT. This characteristic is because even if Vapply increases, the depletion layer remains in the whole intrinsic region, and the electric field changes only near the p-type/intrinsic interface and intrinsic/n-type interface but remains in the most intrinsic region. This characteristic is preferable for some kinds of photosensor applications. Finally, an application example of the p/i/n TFPT, artificial retina, is introduced.

An image sensor for a use of colorimeter is characterized based on the CIE standard colorimetric observer. We use the method of least squares to derive a colorimetric characterization matrix between RGB output signals and CIE XYZ tristimulus values. This paper proposes an adaptive measuring method to obtain the chromaticity of colored scenes and illumination through a 33 camera transfer matrix under a certain illuminant. Camera RGB outputs, sensor status values, and photoelectric characteristic are used to obtain the chromaticity. Experimental results show that the proposed method is valid in the measuring performance.

In this paper, a new formulation of equal-length three-section open stubs having two zeros located on the unit circle and one zero at z=-1 (θ=π) in the Z-plane is presented. In particular, new filter configurations consisting of equal-length two-section open stubs, cascade lines, open stubs, and three-section open stubs are employed to emulate the discrete-time filters. To examine the validity of our formulation, we realized two discrete-time Chebyshev type II low-pass filters in the form of microstrip lines. The frequency responses of these two filters are measured to validate this new formulation.

This paper presents the analysis of a new multi-oscillated current resonant type DC-DC converter. Current resonant converters have several remarkable features such as high efficiency, small size, low cost and low noise, and are frequently employed in many portable electronic systems such as personal computers, cellular phones and flat panel displays. The current resonant type converter generally employs pulse frequency modulation for constant voltage control in the output. For this reason, the magnetizing current through the converter not only causes a power loss under a light load, but also a loss during stand-by. Therefore, this type of converter has a problem in that the required smaller size cannot be achieved, because an auxiliary source is necessary for stand-by. In order to solve these problems, a new current resonant type power supply is proposed in which two driving methods are employed. In these driving methods, one MOSFET as a main switch is driven by an auxiliary winding of the transformer and another MOSFET as a main switch is driven by the driving IC with a low withstand voltage. Good agreement of the observed and simulated waveforms was confirmed. In addition, eight distinct states and four distinct operating modes, which compose of the sequence of states, were clarified by experimental and simulated analysis.

To fully utilize the limited battery energy of mobile electronic devices, we propose an adaptive adjustment method of processing quality for multiple image stream tasks running with widely varying execution times. This adjustment method completes the worst-case executions of the tasks with a given budget of energy, and maximizes the total reward value of processing quality obtained during their executions by exploiting the probability distribution of task execution times. The proposed method derives the maximum reward value for the tasks being executable with arbitrary processing quality, and near maximum value for the tasks being executable with a finite number of processing qualities. Our evaluation on a prototype system shows that the proposed method achieves larger reward values, by up to 57%, than the previous method.

This paper describes a new color segmentation based on a normalized RGB chromaticity diagram for face detection. Face skin is extracted from color images using a coarse skin region with fixed boundaries followed by a fine skin region with variable boundaries. Two newly developed histograms that have prominent peaks of skin color and non-skin colors are employed to adjust the boundaries of the skin region. The proposed approach does not need a skin color model, which depends on a specific camera parameter and is usually limited to a particular environment condition, and no sample images are required. The experimental results using color face images of various races under varying lighting conditions and complex backgrounds, obtained from four different resources on the Internet, show a high detection rate of 87%. The results of the detection rate and computation time are comparable to the well known real-time face detection method proposed by Viola-Jones [11],[12].

This paper considers a proportional fairness of end-to-end session rates in a multihop wireless network through the rate control framework. In multihop wireless networks, there are two classes of rate control problem. One focuses in optimizing the transmission attempt probabilities at the lower layers, but not the transmit powers while other problem is closely related to jointly optimal congestion control and power control. Proportional fairness is a fundamental concept in flow control problems. In this paper, we give in-depth analysis and show that the optimal solutions of these problems are proportionally fair provided that the objective functions are suitably chosen.