The luminance of about 10,000 cd/m2 at an applied voltage of 9.2 V and the external emission efficiency 5.5 cd/A at an injection current density of 50 mA/cm2 have been obtained from an organic light emitting diode (OLED) using starburst molecule doped with 5,6,11,12-tetraphenylnaphthacene fabricated by wet-processing. We demonstrate that the OLEDs fabricated by wet-processing can be applied to fields of short range optical communication as the electro-optical conversion device for transmitting the signals of moving picture.

We have developed a high-power organic radical battery for information technology equipment such as personal computers (PCs). The battery provides several minutes of backup power without an external uninterrupted power source. Since the built-in battery makes energy conversion from AC to DC, or DC to AC, unnecessary, it protects equipment from power failure with no loss of energy. The fabricated battery shows a high power density of 1 kW/L and is capable of driving a desktop PC for several minutes. The use of purely organic polyradicals, poly (2,2,6,6-tetramethylpiperidinyloxy mathacrylate), for the cathode active material opens up a new field of high power density, environmentally friendly batteries.

FEC (Forward Error Correction) is widely used to recover packet loss over the Internet since it does not involve additional network delay. However, FEC still needs much additional network bandwidth for redundancy, and does not consider the priority or the importance of video frames to generate redundant data. In this paper, we present Periodic FEC (PFEC) to make up for the shortcomings of FEC. PFEC divides frames into high-priority frames and low-priority frames, and gives redundancy only to high-priority frames. As specific examples, we describe two types of PFEC: Media-Independent PFEC and Media-Dependant PFEC. Moreover, based on the two-state continuous time Markov chain, we propose redundancy control algorithms of the PFEC schemes that can adjust the amount of redundancy to optimal levels depending on network loss conditions. For better performance, we also consider UEP (Unequal Error Protection) based on PFEC that gives redundancy to low-priority frames as well as high-priority frames. Experimental results show that compared with FEC, PFEC reduces the amount of redundancy considerably but degrades PSNR slightly, and UEP based on PFEC economizes redundancy without the degradation of the PSNR.

We fabricated organic p-n heterojunction, p-i-n heterojunction and all-i-layer photovoltaic cells of a zinc phthalocyanine (ZnPc)/1:1 codeposition (ZnPc:C60)/C60 structure with Al cathode. We investigated the effects of the device structure and the cathode material on the photovoltaic properties. The thickness of the i-layer was changed as 0 nm (= p-n heterojunction), 10 nm (= p-i-n heterojunction) or 50 nm (= all-i-layer) with the total thickness of 50 nm. We also changed cathode materials from Al to low-workfunction Mg:Ag electrode. Photovoltaic properties, i.e., short-circuit current density, fill factor and power conversion efficiency, were strongly influenced by the device structure and cathode material. Finally, the power conversion efficiency showed a maximum (1.5%) with the p-i-n structure and a Mg:Ag cathode under Air Mass 1.5 global solar conditions.

Photoacoustic (PA) spectra on the 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) films deposited by the vacuum evaporation were measured. The films have layered structures constructed from the perylene molecule plane structures. The crystal quality depended on the deposited substrate and the photoacoustic spectroscopy (PAS) seems to be the very useful tools to evaluate these properties from the non-radiative features. The films deposited on the three different substrate had the almost same PL spectra, but the films deposited on the glass substrate had the large non-radiative peaks in the PA spectra contrary to the films deposited on the alumina or crystal Si (100) those had the non-radiative peaks only observed at the short wavelength region.

Thin film of polyurethane having metal complex was prepared by vapor deposition polymerization of bis (5,8-dihydroxyquinoline) zinc (ZnHq2) and 4, 4'-diphenylmethane diisocyanate monomers. The film was applied for the electron-transporting emissive layer of the organic light emitting diode. The deposition-polymerized film was found to give higher quantum efficiency of luminescence than the ZnHq2 monomer film.

Displaying a 3D geometric model of a user in real time is an advantage for a telecommunication system because depth information is useful for nonverbal communication such as finger-pointing and gesturing that contain 3D information. However, the range image acquired by a rangefinder suffers from errors due to image noises and distortions in depth measurement. On the other hand, a 2D image is free from such errors. In this paper, we propose a new method for a shared space communication system that combines the advantages of both 2D and 3D representations. A user is represented as a 3D geometric model in order to exchange nonverbal communication cues. A background is displayed as a 2D image to give the user adequate information about the environment of the remote site. Additionally, a high-resolution texture taken by a video camera is projected onto the 3D geometric model of the user. This is done because the low resolution of the image acquired by the rangefinder makes it difficult to exchange facial expressions. Furthermore, to fill in the data occluded by the user, old pixel values are used for the user area in the 2D background image. We have constructed a prototype of a high presence shared space communication system based on our method. Through a number of experiments, we have found that our method is more effective for telecommunication than a method with only a 2D or 3D representation.

We describe a new inconsistent case which is susceptible to occur while producing consistent answer set using prioritized default logic. We define new semantics for prioritized default logic in order to solve this problem. There is a sign difference between General and Extended logic programs. Extended logic programs are formulated using classical negation, For this reason, an inconsistent answer set can sometimes be produced. For the most part, default reasoning semantics successfully resolved this problem, but a conflict could still arise in one particular case. The purpose of this paper is to present this eventuality, and revise the semantics of default logic in order to give an answer to this problem.

Theoretical calculation has been done on the decay time of photoluminescence of Ir(ppy)3 dissolved in tetrahydrofuran and its temperature dependence at 1.2-300 K. Taking into account that the emitting triplet state consists of three zero-field splitting substates and taking into account one-phonon non-radiative transitions among these substates, the rate equations for the populations of these substates have been obtained. Three decay components are derived by solving not only the secular equation but also the rate equations, where the slow decay time shows decrease from 145 to 2 µs with increasing temperature from 1.2 to 300 K. A good agreement has been obtained for the temperature dependence between the calculated slow decay time and the observed one.

In wide-area wireless access systems such as satellite communications systems and stratospheric platform systems, electric power supplies for radio communications are realized using solar photovoltaic cells and/or fuel cells. However, the on-board weight limits restrict the number of cells that can be equipped. In addition, the transmission power of such systems is limited taking account of issues and regulations on sharing the same frequency band with other systems. Hence, both the frequency band and electric power is limited, which are crucial radio resources for those systems. Although radio channel allocation methods taking account of the frequency constraint only or the power constraint only have been proposed, radio channel allocation methods taking account of both constraints simultaneously have been insufficiently studied. This paper proposes a radio channel allocation method that provides global optimum allocation results by utilizing the linear programming method. The proposed method has features such that the method first allocates radio channels in proportion to the traffic demand distributed over the service coverage area and then maximizes the total radio channels allocated to systems. Numerical results are presented for a stratospheric platform system that covers an area of Japan, as an example, to demonstrate that the proposed method optimally allocates radio channels taking account of both constraints while efficiently allocating excess resources. In addition, whether a system reaches either the frequency or power limit can be estimated, by investigating the radio channel allocation results. Furthermore, enhanced linear programming models based on a method aiming at practical use of the radio channel allocation results in operation are also introduced. The enhanced model is demonstrated to work effectively to avoid unbalanced radio channel allocations over geographical areas. The proposed method and linear programming models are useful not only for making pre-plans but also for determining the amount of necessary frequency and power resources in designing systems.

In this paper, iterative adaptive soft parallel interference canceller (ASPIC) is proposed for turbo coded multiple-input multiple-output (MIMO) multiplexing. ASPIC is applied to transform a MIMO channel into single-input multiple-output (SIMO) channels for maximum ratio diversity combining (MRC). In the ASPIC, replicas of the interference are generated and subtracted from the received signals. For the generation of replicas with higher reliability, iterative ASPIC is proposed. It performs the iterative interference cancellation by feedback of the log-likelihood ratio (LLR) sequence obtained as the turbo decoder output. For iterative ASPIC, at the transmitter, the information sequence and parity sequence are transmitted from different antennas. In this paper, the achievable bit error rate (BER) performance, in a Rayleigh fading channel, for the turbo coded MIMO multiplexing with the proposed iterative ASPIC system is evaluated by computer simulation.

We have demonstrated improvement in the efficiency of TDAPB-based OLEDs. The external quantum efficiency of 8.2% and a power efficiency of 17.3 lm/W were achieved. The results suggest that using the starburst small-molecule TDAPB allows for easy fabrication and is effective for achieving high efficiencies in simple device structures.

The polarized absorption measurement was employed to investigate the orientational order of the 4-n-4-pentyl-cyanobiphenyl (5CB) film of sub-nanometer thick. It was confirmed that this optical technique is simple but effective to observe the second orientational order parameter, S2, of the organic ultra thin film at the interface region.

In multicarrier code division multiple access (MC-CDMA) systems, the orthogonality among the spreading codes is destroyed because the channels exhibit frequency-selective fading and the despreading stage performs gain control; that is, inter-code interference (ICI) can significantly degrade system performance. This paper proposes an optimum spreading code assignment method that reflects our analysis of ICI for up and downlink MC-CDMA cellular systems over correlated frequency-selective Rayleigh fading channels. At first, we derive theoretical expressions for the desired-to-undesired signal power ratio (DUR) as a quantitative representation of ICI; computer simulation results demonstrate the validity of the analytical results. Next, based on the ICI imbalance among code pairs, we assign specific spreading codes to users to minimize ICI (in short, to maximize the multiplexing performance); our proposed method considers the quality of service (QoS) policy of users or operators. We show that the proposed method yields better performance, in terms of DUR, than the conventional methods. The proposed method can maximize the multiplexing performance of a MC-CDMA cellular system once the channel model, spreading sequence, and combining strategy have been set. Three combining strategies are examined at the despreading stage for the uplink, equal gain combining (EGC), orthogonality restoring combining (ORC), and maximum ratio combining (MRC), while two are considered for the downlink, EGC and MRC.

Electronic Toll Collection (ETC), an application of Dedicated Short Range Wireless Communication (DSRC), had suffered from wrong operations due to multipath problems. To solve this problem, we proposed to apply a simple configured path determination scheme for the ETC system. The system consists of a vector network analyzer, low-noise amplifier, and X-Y positioner and achieves an automatic measurement of the spatial transfer function with emphasis on accurate measurement and reproducibility. For the reliable identification of the propagating paths, 3-D Unitary ESPRIT and SAGE algorithms were employed. Having developed the system, field experiments at the toll gate of the highway was carried out. In the measurements, we could determine many propagation paths so that the dominant propagation phenomena at the toll gate was identified. They included a ground-canopy twice reflected wave, which was a potential path that caused wrong operation. Consequently, their reflection coefficients and polarization characteristics were investigated. From the results, applicability of the path determination system for short range on-site measurement was confirmed.

This letter develops a practical sectorized antenna array using center-fed half-wavelength dipole antennas that are parallel to and a distance in front of a large ground plane reflector. Each element in the array is designed to provide coverage to isolate each 120sector from adjacent sectors. We derive a closed-form expression for spatial correlation function that can be used as guides in evaluating the effects of array spatial correlation on diversity performance in sectorized cellular communications.

In this letter, a circular microstrip patch antenna with a conical cup is proposed. The results of a simulation and experiment show that the conical cup has a beneficial effect on the antenna's gain and principal plane beamwidths. The maximum gain of this antenna was 12.6 dBi, which is about 3 dB higher than one with a cylindrical cup. The 3-dB beamwidths of the E-and H-planes were 34and 44, respectively.

This paper presents an asynchronous data transfer scheme using 2-color 2-phase dual-rail encoding based on a differential operation and its circuit realization. The proposed encoding enables seamless asynchronous data transfer without inserting a spacer, because each logic value is represented by two kinds of codewords with dual-rail, called "color" data. Since the difference x-x between components of a codeword (x,x) becomes constant in every valid state, the data-arrival state can be detected by calculating the difference x-x. From the viewpoint of circuit implementation, during the state transition, since the dual-rail x and x are defined so as to transit differentially, the compatibility with a comparator using a differential amplifier becomes high, which results in reduction of the cycle time. It is evaluated using HSPICE simulation with a 0.18 µm CMOS technology that communication speed using the proposed dual-rail encoding becomes 1.4 times faster than that using conventional dual-rail encoding.

An experimental model of a redox microarray, which provides a foundation for constructing future massively parallel molecular computers, is proposed. The operation of a redox microarray is confirmed, using an experimental setup based on an array of microelectrodes with analog integrated circuits.

In this paper, we propose an optimal power control algorithm with fast convergence rate for CDMA cellular systems. The new power control algorithm is based on linear quadratic control theory (LQR). Using the state feedback control designed to minimize an objective function, each mobile performs a successful transmission with optimal power. Simulation results show a fast convergence rate to target SIR with less power consumption, and an augmented channel capacity through decreased outage probability.