High‐current lightning discharges in winter

Lightning electric‐field waveforms related to power line faults in winter have been identified. Most of those waveforms appear to be associated with upward lightning discharges with absolute peak currents of over 100 kA. They are quite different from common return‐stroke waveforms, and the lightning discharges which produce these characteristic waveforms are called GC (Ground to Cloud) flashes. These high‐current lightning discharges are distributed around the coastline in different ways depending on their polarities. The spatial distributions of high‐current lightning discharges around Japan are also investigated. It is revealed that the region of Honshu Island along the coastline of the Sea of Japan belongs to the area in which the density of high‐current lightning flashes is the highest in Japan through the year. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 8–15, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20874     

Colorless polyimides derived from 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride,self-orientation behavior during solution casting,and their optoelectronic applications

A novel cycloaliphatic monomer for polyimides (PI), 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride (H′-PMDA) is proposed in this work. H′-PMDA shows high polymerizability with various diamines in contrast to its isomer, i.e., conventional hydrogenated pyromellitic dianhydride (H-PMDA) and leads to highly flexible and colorless PI films with very high T_g's. In particular, the combinations with rigid structures of diamines give rise to PIs with significantly decreased coefficients of thermal expansion (CTE) owing to high extents of in-plane chain orientation induced by thermal imidization, whereas the H-PMDA-based counterparts do not. The decreased CTE reflects structural rigidity/linearity of the H′-PMDA-based diimide units as supported by liquid crystallinity observed in the corresponding model compound. Solution casting of a chemically imidized PI derived from H′-PMDA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) results in a lower CTE than that of the thermally imidized counterpart, suggesting the presence of a self-orientation phenomenon during solvent evaporation. The mechanism is proposed in this work. H′-PMDA/TFMB and its copolymer systems can be useful as plastic substrates in image display devices and/or novel coating-type optical compensation films.     

Isolation,purification and characterisation of angiotensin I‐converting enzyme–inhibitory peptides derived from catfish (Clarias batrachus) muscle protein thermolysin hydrolysates

The angiotensin I‐converting enzyme (ACE)‐inhibitory activities of catfish (Clarias batrachus) muscle protein hydrolysates were investigated. Thermolytic digests of C. batrachus sarcoplasmic and myofibrillar proteins exhibited inhibitory activity towards ACE and were purified with the aim of ultrafiltration, gel filtration and reversed‐phase high‐performance liquid chromatography (RP‐HPLC). The amino acid sequences of hydrolysates with the highest ACE‐inhibitory activities were determined using electrospray quadrupole time‐of‐flight tandem mass spectrometry (ESI‐TOFQ MS/MS). The sequences of GPPP (IC₅₀ = 0.86 μm ) and IEKPP (IC₅₀ = 1.2 μm ) corresponding to the fragments 986–989 and 441–445 of myosin‐I heavy chain were identified for the sarcoplasmic and myofibrillar protein hydrolysates, respectively. Peptide GPPP exhibited a mixed‐type inhibition whereas peptide IEKPP could only bind to the active sites of ACE. The results demonstrate that hydrolysates of C. batrachus muscle proteins obtained by thermolysin may contain bioactive peptides.     

Development of rapid hygrothermal pasteurization using saturated water vapor

We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100 °C. In the present study, the effects of RHP on microbiological quality and quality attributes such as color changes, firmness and ascorbic acid content on many fresh-cut fruits and vegetables (cabbage, cucumber, carrot, cherry tomato, bell pepper, strawberry, pineapple and melon) were investigated. The RHP was performed within a second by free-falling samples through a cylindrical processing chamber filled with steam. The RHP resulted in a 0.7–2.0 log order reduction in the numbers of naturally inoculated mesophilic bacteria. Furthermore, the RHP induced no significant changes in color and firmness of samples, except on the leafy vegetable, cabbage. Ascorbic acid was also retained approximately 80% and above. These results indicate that the RHP is a clean and effective method for decontaminating mesophilic bacteria on fresh fruits and vegetables with minimal changes in quality.Industrial relevanceIn fresh-cut industry, an effective and risk-free decontamination technology is required for use in place of a conventional method, washing by chlorine that can produce carcinogenic chlorinated by-products. In this study, the rapid hygrothermal pasteurization (RHP) method using saturated water vapor was invented and their ability for applying minimal processing was evaluated. The results showed that RHP, without using chemicals, can reduce microorganism load and preserve quality attributes in many kinds of fresh-cut fruits and vegetables. Therefore, RHP could be used as a novel method, which can be generally applicable to fresh-cut fruits and vegetables in the food industry.     

Product mix problems considering several probabilistic conditions and flexibility of constraints

This paper considers product mix problems including randomness of future returns, ambiguity of coefficients and flexibility of upper value with respect to each constraint such as budget, human resource, time and several costs. Particularly, the flexibility is assumed to be a fuzzy goal. Then, several models based on maximizing total future profits under a level of satisfaction to each fuzzy goal are proposed. Furthermore, the model considering preference ranking to each fuzzy goal of constraints is proposed. Since these problems are basically formulated as nonlinear programming problems, the transformations into deterministic equivalent problems are introduced and the efficient solution methods are developed. A numerical example for product mix problem is given to illustrate our proposed models.     

Design and test of hydraulic vacuum breaker check valve for simplified boiling water reactor

In the current design of the simplified boiling water reactor, the vacuum breaker check valve is an important safety component. The vacuum breaker check valve is the only key safety components which is not passive in nature. Failure of this mechanical valve drastically reduces the passive containment cooling system cooling capability and hence containment pressure may exceed the design pressure. To eliminate this problem novel vacuum breaker check valve was developed to replace the mechanical valve. This new design is based on a passive hydraulic head, which is fail-safe and is truly passive in operation. Moreover this new design needs only one additional tank and one set of piping each to the wetwell and drywell. This system is simple in design and hence is easy to maintain and to qualify for operation. The passive vacuum breaker check valve performance was first evaluated using RELAP5. Then the passive vacuum breaker check valve was constructed and implemented in the PUMA integral test facility. Its performance was studied in a large break loss of coolant accident simulation test performed in PUMA facility.     

产品设计对改进产品生命终期的影响

本研究的主要目标是在鼓励创造性思维的同时，建立一个结构化方法用于阐明产品生命周期策略。当前提倡采用适用于大多数产品的通用规则。联系“通用性”原则，与“放之四海皆准”的方法相比，本研究找出了影响产品生命终期的主要因素。研究结果可分为两个核心部分。第一，根据产品的技术特性，该方法论确定了合理的产品生命终期策略第二，为了评估和验证该方法，将产品生命终期策略的分类和当前工业实践进行了对比，开发的产品生命终期设计顾问(ELDA)软件，指导生产商确定适合的产品生命终期策略。对产品生命终期进行分类的能力使得设计者能够重新设计对环境负荷较小产品。这篇文章为设计者和生产管理者提供了合适的产品生命终期策略。通过更深入的理解相应产品的生命终期策略，本文的研究结果能够帮助设计者开发适合他们情况的、系统的产品生命终期策略。通过技术革新或者价值链的改进，将ELDA的结果运用于生命终期改善。     

Randomized algorithms for synthesis of switching rules for multimodal systems

In this paper, we consider the design of globally asymptotically stabilizing state-dependent switching rules for multimodal systems, first restricting attention to linear time-invariant (LTI) systems with only two states for the switch, and then generalizing the results to multimodal LTI systems and to nonlinear systems. In all cases, the systems considered do not allow the construction of a single quadratic Lyapunov function and, hence, fall in the class of problems that require multiple Lyapunov functions and thus are nonconvex. To address the challenge of nonconvexity , we introduce probabilistic algorithms, and prove their probability-one convergence under a new notion of convergence. Then, to reduce complexity, we develop modified versions of the algorithm. We also present a class of more general nonconvex problems to which this approach can be applied. The results are illustrated using two- and three-dimensional systems with multiple switch states.     

Acrobot control by learning the switching of multiple controllers

Reinforcement learning (RL) has been applied to constructing controllers for nonlinear systems in recent years. Since RL methods do not require an exact dynamics model of the controlled object, they have a higher flexibility and potential for adaptation to uncertain or nonstationary environments than methods based on traditional control theory. If the target system has a continuous state space whose dynamic characteristics are nonlinear, however, RL methods often suffer from unstable learning processes. For this reason, it is difficult to apply RL methods to control tasks in the real world. In order to overcome the disadvantage of RL methods, we propose an RL scheme combining multiple controllers, each of which is constructed based on traditional control theory. We then apply it to a swinging-up and stabilizing task of an acrobot with a limited torque, which is a typical but difficult task in the field of nonlinear control theory. Our simulation result showed that our method was able to realize stable learning and to achieve fairly good control.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

Address‐While‐Display technique combined with gas‐discharge AND logic for driving AC‐PDPs

A hybrid AWD/AND drive technique has been developed in which an Address‐While‐Display (AWD) scheme is combined with an AND logic characteristic that gas discharges demonstrate. The AWD technique enables AC‐PDPs to be driven at high luminance, while the AND logic reduces the number of scan drivers by an order of magnitude. A detailed analysis of the addressing operation has been made. The hybrid drive utilizes the AND logic in two ways: (1) a combination of two voltage pulses and (2) a combination of a voltage pulse and discharge‐priming particles. It was found that the addressing operation requires the establishment of a discharge between the scan and data electrodes, and also between the scan and display electrodes.