We determine the annealing dynamics of AsGa antisite defects in As ion-implanted GaAs. An Arrhenius plot of the carrier decay rate or the defect density vs. the annealing temperature in the high temperature regime gives an energy EPA, which is different from true activation energy. The annealing time dependence of EPA obtained by the two diffusion models (self diffusion of AsGa antisite defects and VGa vacancy assisted diffusion of AsGa antisite defects) are compared with EPA's obtained from already published works. The results prove that the diffusion of AsGa antisite defects is assisted by the VGa vacancy defects that exist in a high density.

We have proposed a diffusion-type flow control mechanism to achieve the extremely time-sensitive flow control required for high-speed networks. In this mechanism, each node in a network manages its local traffic flow only on the basis of the local information directly available to it, by using predetermined rules. In this way, the implementation of decision-making at each node can lead to optimal performance for the whole network. Our previous studies concentrated on the flow control for a single flow. In this paper, we propose a diffusion-type flow control mechanism for multiple flows. The proposed scheme enables a network to quickly recover from a state of congestion and to achieve fairness among flows.

It has been shown that the maskless dye-diffusion technique is applicable to a conjugated polymer poly(9,9-dioctylfluorene). The introduction of Coumarin 6 and Nile red results in green and white emission, with the increased onset voltage for the both cases. It has also been confirmed that the heat treatment effect during the maskless dye diffusion technique results in not the increase but the decrease of the onset voltage, indicating that the dye plays a role of carrier trap in the polymer.

We have developed a solid-electrolyte nonvolatile switch (here we refer as NanoBridge) with a low ON resistance and its small size. When we use a NanoBridge to switch elements in a programmable logic device, the chip size (or die cost) can be reduced and performance (speed and power consumption) can be enhanced. Developing this application required solving a couple of problems. First, the switching voltage of the NanoBridge (0.3 V) needed to be larger than the operating voltage of the logic circuit (>1 V). Second, the programming current (>1 mA) needed to be suppressed to avoid large power consumption. We demonstrate how the Nanobridge enhances the switching voltage and reduces the programming current.

In current IP-based networks, the application of window-based end-to-end flow control, including TCP, to ensure reliable flows is an essential factor. However, since such a flow control is provided by the end hosts, end-to-end control cannot be applied to decision-making in a time-scale shorter than the round-trip delay. We have previously proposed a diffusion-type flow control mechanism to realize the extremely time sensitive flow control that is required for high-speed networks. In this mechanism, each network node manages its own traffic only on the basis of the local information directly available to it, by using predetermined rules. The implementation of decision-making at each node can lead to optimal performance for the whole network. Our previous studies showed that the mechanism works well, by itself, in high-speed networks. However, to apply this mechanism to actual networks, it needs to be able to coexist with other existing protocols. In this paper, we investigate the performance of diffusion-type flow control coexisting with TCP. We show that diffusion-type flow control can coexist with TCP and the two can be complementary. Then, we show that a combination of both controls achieves higher network performance than TCP alone in high-speed networks.

A 3 dimensional (3D) error diffusion method based on edge detection for flat panel display (FPD) is presented. The new method diffuses errors to the neighbor pixels in current frame and the neighbor pixel in the next frame. And the weights of error filters are dynamically adjusted based on the results of edge detection in each pixel's processing, which makes the weights coincide with the local edge feathers of input image. The proposed method can reduce worm artifacts and improve reproduction precision of image details.

We developed a system that detects the vehicle driving immediately ahead of one's own car in the same lane and measures the distance to and relative speed of that vehicle to prevent accidents such as rear-end collisions. The system is the first in the industry to use non-scanning millimeter-wave radar combined with a sturdy stereo image sensor, which keeps cost low. It can operate stably in adverse weather conditions such as rain, which could not easily be done with previous sensors. The system's vehicle detection performance was tested, and the system can correctly detect vehicles driving 3 to 50 m ahead in the same lane with higher than 99% accuracy in clear weather. Detection performance in rainy weather, where water drops and splashes notably degraded visibility, was higher than 90%.

We have fabricated and investigated InGaAs Esaki tunnel diodes, grown on GaAs or InP substrates, of varied defect densities. The tunnel diodes exhibit the same I-V characteristics in spite of the variation of defect density. Under the simple thermal annealing and forward current stress tests, the change in the valley current was not observed, indicating that defects were not increased. On the other hand, the reduction in the peak current due to the carbon diffusion was observed under both tests. The diffusion was enhanced by the stress current owing to the energy dissipation associated with the nonradiative electron-hole recombination. From the reduction rates of the peak current, we obtained the thermal and current-enhanced carbon diffusion constants in InGaAs, which are independent of defect density. Although thermal diffusion of carbon in InGaAs is comparable with that in GaAs, the current-induced enhancement of diffusion in InGaAs is extremely weaker than that in GaAs. The difference between activation energy of thermal and current-enhanced diffusion is 0.8 eV, which is independent of stress current density and close to InGaAs bandgap energy. This indicates that the current-enhanced diffusion is dominated by the energy dissipation associated with nonradiative band-to-band recombination. This enhancement mechanism well explains that the current-induced enhancement is independent of defect density and extremely weak. We also have found that the current-enhanced diffusion constant is approximately proportional to the square of current density, suggesting that the recombination in the depletion layer dominates the current-enhanced diffusion.

We propose a novel strategy to obtain a high spatio-temporal resolution video. To this end, we introduce a dual sensor camera that can capture two video sequences with the same field of view simultaneously. These sequences record high resolution with low frame rate and low resolution with high frame rate. This paper presents an algorithm to synthesize a high spatio-temporal resolution video from these two video sequences by using motion compensation and spectral fusion. We confirm that the proposed method improves the resolution and frame rate of the synthesized video.

A triple density Error Diffusion for medical monochrome LCDs is proposed to improve their gray-scale precisions. In addition, a measurement technique of image qualities based on E-MSE (Eye model-based Mean Square Error) is proposed. Several conventional techniques for medical LCDs, such as Sub-Pixel Modulation and Error Diffusion, are evaluated based on E-MSE and the validity of the proposed technique is ensured objectively.

We propose a novel blind watermarking algorithm, called XFuseMark, which can hide a small, visually meaningful, grayscale logo in a host image instead of using a random-noise-like sequence based on the multiresolution fusion principles, and extract a recognizable version of the embedded logo even without reference to the original host data at the receiving end. XFuseMark is not only secure, i.e., only authorized users holding a private key are able to conduct the logo extraction operation, but also robust against noise addition and image compression. Experiments verify the practical performance of XFuseMark.

We clarify the effective range of distance between the front and rear images of the depth-fused 3-D (DFD) visual illusion. The DFD visual illusion is perceived when two images with many edges in the front and rear frontal-parallel planes at different depths are overlapped from the viewpoint of an observer. We evaluated how the fusion of the DFD visual illusion depended on the difference in distance between the front and rear images when the distance between the two images was changed. Subjective tests clarified the cases where DFD can be applied.

This paper presents a shortest path search algorithm using a model of excitable reaction-diffusion dynamics. In our previous work, we have proposed a framework of Digital Reaction-Diffusion System (DRDS)--a model of a discrete-time discrete-space reaction-diffusion system useful for nonlinear signal processing tasks. In this paper, we design a special DRDS, called an "excitable DRDS," which emulates excitable reaction-diffusion dynamics and produces traveling waves. We also demonstrate an application of the excitable DRDS to the shortest path search problem defined on two-dimensional (2-D) space with arbitrary boundary conditions.

This paper proposes a novel speech synthesis method to generate human-like natural speech. The conventional unit-selection-based synthesis method selects speech units from a large database, and concatenates them with or without modifying the prosody to generate synthetic speech. This method features highly human-like voice quality. The method, however, has a problem that a suitable speech unit is not necessarily selected. Since the unsuitable speech unit selection causes discontinuity between the consecutive speech units, the synthesized speech quality deteriorates. It might be considered that the conventional method can attain higher speech quality if the database size increases. However, preparation of a larger database requires a longer recording time. The narrator's voice quality does not remain constant throughout the recording period. This fact deteriorates the database quality, and still leaves the problem of unsuitable selection. We propose the plural unit selection and fusion method which avoids this problem. This method integrates the unit fusion used in the unit-training-based method with the conventional unit-selection-based method. The proposed method selects plural speech units for each segment, fuses the selected speech units for each segment, modifies the prosody of the fused speech units, and concatenates them to generate synthetic speech. This unit fusion creates speech units which are connected to one another with much less voice discontinuity, and realizes high quality speech. A subjective evaluation test showed that the proposed method greatly improves the speech quality compared with the conventional method. Also, it showed that the speech quality of the proposed method is kept high regardless of the database size, from small (10 minutes) to large (40 minutes). The proposed method is a new framework in the sense that it is a hybrid method between the unit-selection-based method and the unit-training-based method. In the framework, the algorithms of the unit selection and the unit fusion are exchangeable for more efficient techniques. Thus, the framework is expected to lead to new synthesis methods.

There is increasing evidence from in vivo recordings in monkeys trained to respond to stimuli by making left- or rightward eye movements, that firing rates in certain groups of neurons in oculo-motor areas mimic drift-diffusion processes, rising to a (fixed) threshold prior to movement initiation. This supplements earlier observations of psychologists, that human reaction-time and error-rate data can be fitted by random walk and diffusion models, and has renewed interest in optimal decision-making ideas from information theory and statistical decision theory as a clue to neural mechanisms. We review results from decision theory and stochastic ordinary differential equations, and show how they may be extended and applied to derive explicit parameter dependencies in optimal performance that may be tested on human and animal subjects. We then briefly describe a biophysically-based model of a pool of neurons in locus coeruleus, a brainstem nucleus implicated in widespread norepinephrine release. This neurotransmitter can effect transient gain changes in cortical circuits of the type that the abstract drift-diffusion analysis requires. We also describe how optimal gain schedules can be computed in the presence of time-varying noisy signals. We argue that a rational account of how neural spikes give rise to simple behaviors is beginning to emerge.

We report the empirically obtained conditions for the fusion splicing with photonic crystal fibers (PCF) having large mode areas. By controlling the arc-power and the arc-time of a conventional electric-arc fusion splicer, the splicing loss between two PCFs could be lowered down to 0.2 dB in average. For the splicing PCF with a conventional single mode fiber (SMF), the loss was increased due to the modal field mismatch, but still below 0.45 dB in average. The tensile strength was weakened by the splicing from 2.83 GPa down to 1.04 GPa for the PCF-PCF case and 0.89 GPa for the PCF-SMF one.

We have proposed diffusion-type flow control as a solution for the extremely time-sensitive flow control required for high-speed networks. In our method of flow control, we design in advance simple and appropriate rules for action at the nodes, and these automatically result in stable and efficient network-wide performance through local interactions between nodes. Specifically, we design the rules for the flow control action of each node that simulates the local interaction of a diffusion phenomenon, in order that the packet density is diffused throughout the network as soon as possible. However, in order to make a comparison with other flow control methods under the same conditions, the evaluations in our previous studies used a closed network model, in which the number of packets was unchanged. This paper investigates the performance of our flow control method for an end-to-end flow, in order to show that it is still effective in more realistic networks. We identify the key issues associated with our flow control method when applied to an open network model, and demonstrate a two-step solution. First, we consider the rule for flow control action at the boundary node, which is the ingress node in the network, and propose a rule to achieve smooth diffusion of the packet density. Secondly, we introduce a shaping mechanism, which keeps the number of packets in the network at an appropriate level.

Charge carrier generation, transport, and exciton diffusion in f ac tris(2-phenylpyridine)iridium(III) Ir(ppy)3 doped in 4,4'-N,N'-dicarbazole-biphenel (CBP) thin films, an emissive layer of green electrophosphorescent devices, have been studied in terms of time-of-flight (TOF) transient photocurrent, steady-state photocurrent and time-resolved photoluminescence (PL) spectroscopies. It is found that the excitation energy rapidly transfer from CBP to Ir(ppy)3, and that the charge carriers are generated on Ir(ppy)3 sites. With increasing Ir(ppy)3 concentration, the electron drift mobility is slightly decreased, while the hole transit signals become unobservable. The electron and hole transport properties of Ir(ppy)3 doped CBP thin films result from the energy levels of the lowest unoccupied molecular orbital and the highest occupied molecular orbital of Ir(ppy)3 with respect to those of CBP. From steady-state photocurrent measurement, the diffusion lengths of 3.5% and 7.0% Ir(ppy)3 doped CBP thin films are determined to be 21 nm and 50 nm, respectively.

Digital halftoning is used to quantize a grayscale image to a binary image. Error diffusion halftoning generates a high-quality binary image, but also generates some defects such as the warm effect, sharpening, and so forth. To reduce these defects, Kite proposed a modified threshold modulation method that utilizes a multiplicative parameter for controlling sharpening. Nevertheless, some degradation was observed near the edges of objects with a large luminance change. In this paper, we propose a method of controlling the multiplicative parameter in proportion to the magnitude of the local edge slope. The results of computer simulation show a greater reduction of sharpening in the halftone image. In particular, there is a great improvement in the quality of the edges of objects with a large luminance change.

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.