Low‐temperature poly‐Si TFT transferred onto plastic substrates by using surface free technology by laser ablation/annealing (SUFTLA®)

A novel technology that makes it possible to transfer electronic devices from an original substrate to another substrate is introduced. Because laser irradiation is utilized during the transfer process, this technology was named SUFTLA® (surface free technology by laser ablation/annealing). Low‐temperature poly‐Si TFTs first manufactured on a quartz substrate were transferred onto a PES substrate without any damage or characteristic degradation. A trial TFT‐LCD device with peripheral integrated driver circuits was also transferred onto the PES substrate and their operation was observed under typical conditions. These results indicate that the SUFTLA technology is one of the leading candidates for fine‐patterned high‐performance electronic‐device manufacturing on flexible substrate.     

Analysis of drain ac stress‐induced hot‐carrier degradation in low‐temperature poly‐Si TFTs

We investigated hot‐carrier degradation in low‐temperature (≤425° C) polycrystalline‐silicon thin‐film transistors (poly‐Si TFTs). When the appropriate stress is applied to the TFTs, a decrease in on‐current and an increase in off‐current are induced by the drain avalanche hot carriers (DAHC). The extent of the degradation is quite large, however, when the ac stress is applied to the drain (drain ac stress). Moreover, the degradation is accelerated by an increase in the frequency of the drain ac stress. We found that the pulse number of the drain ac stress dominated this degradation. It is well known that hot carriers are generated by impact ionization, and the impact ionization rate increases with an increase in the carrier density and the electric field in the channel. When the dc stress is supplied to the drain (drain dc stress), the electric field near the drain is high, while the electron density near the drain is low because of the formation of a pinch‐off region. On the other hand, for the case of drain AC stress, both the electric field and electron density near the drain become high during the transition when the voltage of the stress pulse changes from low to high. The impact ionization rate increases at this point. As this cycle is repeated, it is thought that the degradation of TFTs is accelerated.     

Substring-based machine translation

Machine translation is traditionally formulated as the transduction of strings of words from the source to the target language. As a result, additional lexical processing steps such as morphological analysis, transliteration, and tokenization are required to process the internal structure of words to help cope with data-sparsity issues that occur when simply dividing words according to white spaces. In this paper, we take a different approach: not dividing lexical processing and translation into two steps, but simply viewing translation as a single transduction between character strings in the source and target languages. In particular, we demonstrate that the key to achieving accuracies on a par with word-based translation in the character-based framework is the use of a many-to-many alignment strategy that can accurately capture correspondences between arbitrary substrings. We build on the alignment method proposed in Neubig et al. (Proceedings of the 49th Annual Meeting of the Association for Computational Linguistics. Portland, Oregon, pp. 632–641, 2011), improving its efficiency and accuracy with a focus on character-based translation. Using a many-to-many aligner imbued with these improvements, we demonstrate that the traditional framework of phrase-based machine translation sees large gains in accuracy over character-based translation with more naive alignment methods, and achieves comparable results to word-based translation for two distant language pairs.     

Fundamental Technologies and Recent Advances of Cell-Sheet-Based Tissue Engineering

Tissue engineering has attracted significant attention since the 1980s, and the applications of tissue engineering have been expanding. To produce a cell-dense tissue, cell sheet technology has been studied as a promising strategy. Fundamental techniques involving tissue engineering are mainly introduced in this review. First, the technologies to fabricate a cell sheet were reviewed. Although temperature-responsive polymer-based technique was a trigger to establish and spread cell sheet technology, other methodologies for cell sheet fabrication have also been reported. Second, the methods to improve the function of the cell sheet were investigated. Adding electrical and mechanical stimulation on muscle-type cells, building 3D structures, and co-culturing with other cell species can be possible strategies for imitating the physiological situation under in vitro conditions, resulting in improved functions. Finally, culture methods to promote vasculogenesis in the layered cell sheets were introduced with in vivo, ex vivo, and in vitro bioreactors. We believe the present review that shows and compares the fundamental technologies and recent advances for cell-sheet-based tissue engineering should promote further development of tissue engineering. The development of cell sheet technology should promote many bioengineering applications.     

Change in piezoelectric boundary acoustic wave characteristics with overlay and metal grating materials

This paper describes how the characteristics of shear-horizontal type piezoelectric boundary acoustic waves (PBAWs) change with combination of different overlay and metal grating materials. It is shown that PBAWs are supported in various structures provided that highly piezoelectric material(s) are employed as structural member(s). For verification, numerical simulation of different material combinations is done. The results are in good agreement with the qualitative prediction. That is, large electromechanical coupling factor K² is obtainable when materials having small mass densities shear modulus c₄₄ and shear velocity VBS; and materials having extremely large shear modulus c₄₄ are chosen, respectively, for overlay and metallic grating. When YX-LiNbO₃ is assumed as a substrate, for example, the best choice seems to be SiO₂ and Au for overlay and metallic grating, respectively. Although metals with extremely large ρ and c₄₄ such as W and Ta offer large K², they may not be acceptable for practical PBAW applications because of their large electric resistivity.     

Sugar-dependent solubility and fluorescence property of copolymers consisting of phenylboronic acid and 2-hydroxyethyl methacrylate moieties

Copolymers consisting of N-3-acrylamidophenylboronic acid (APBA) and 2-hydroxyethyl methacrylate moieties (HEMA) were synthesized and their solubility and fluorescence properties were evaluated in the presence of sugar. The APBA–HEMA copolymer composed of 25 mol% of APBA moiety was found to be poorly soluble in water at pH 7.4. However, the water solubility of APBA–HEMA was improved in the presence of fructose in solution. The solubility of APBA–HEMA was influenced by fructose in a concentration-dependent manner, due to the formation of boronate ester of APBA moiety with fructose added. In addition, APBA–HEMA was modified with fluorescein isothiocyanate (FITC) for the fluorometric detection of sugars. The fluorescence intensity of FITC-modified APBA–HEMA was dependent on the type and concentration of sugars in solution. The fluorescence intensity of FITC-modified APBA–HEMA was highly enhanced by the addition of fructose, while the fluorescent response was negligibly small when other sugars were added. Thus, usefulness of FITC-modified APBA–HEMA for the selective determination of fructose was demonstrated.     

Design of controller switching strategy for reusable launch vehicle with elevon jamming failure

When a reusable launch vehicle (RLV) returns to earth, it flies just by gliding without thrust. In this phase, one of the most likely and important faults to occur in the airframe is a jamming of the elevon. To tolerate this failure, the flight control system must keep stability and performance during such a failure. One of the effective ways to overcome this problem is to switch the controllers based on the information of the detected failure in the plant. Generally speaking, the controller must have integrators so as to yield the zero steady‐state error for the controlled output even if there exist some perturbations in the plant dynamics. In this paper, the design of controller switching scenario is addressed especially focusing on the decision of the controller state at the instant of switching the controllers with integrator. Then, the proposed switching scenario is applied to the control of ALFLEX (Automatic Landing FLight EXperiment), which is the automatic landing experimental vehicle being developed for RLV, considering the occurrence of the jamming fault. Some simulations are shown to verify the usefulness of the proposed idea. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 80–90, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20356     

Parameter design of event‐driven logic controller for two‐wheeled vehicle

Programmable Logic Controllers (PLCs) are widely used in industry. In PLC‐based control systems, low‐resolution (especially ON‐/OFF) sensors are inexpensive, and actuators are commonly used because they are compatible with programming languages used in PLCs. PLC switches the actuators ON/OFF as the state of the sensor changes between ON/OFF. In designing PLC‐based systems, the design of the parameters of these sensors and actuators (e.g., position of limit switches and torque of motors) is an important problem because they affect the overall performance of the system. This problem, however, has not yet been fully discussed. In the present paper, a systematic design method for this problem is developed. The main concept is to express the model of the system as a Mixed Logical Dynamical System (MLDS) and to formulate the problem as a mathematical programming problem. The developed idea is applied to the line‐following control of a two‐wheeled vehicle. The usefulness of the proposed method is demonstrated through simulation and experiments. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 51–60, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20584