Membrane degradation mechanism during open-circuit voltage hold test

A detailed analysis is made of the relation between the degradation behavior of a membrane electrode assembly (MEA) and deposited Pt (Pt band) in the membrane during an open-circuit voltage (OCV) hold test. Molecular-structural changes in the membrane are investigated by micro-Raman spectroscopy. When the Pt band was not significantly observed in the membrane after the test, the membrane is relatively stable. In contrast, when the Pt band was clearly formed, the membrane around it was intensively degraded. The magnitude of the fluoride ion emission rate (FER) of the effluent water from the anode and the cathode was also consistent with the location of the Pt band. It was verified that the Pt band is one of the factors accelerating membrane degradation, and the catalyst materials strongly affects the degradation. Besides, not the cation transport which enhances the degradation but the kinetics of either the H₂O₂ and/or hydroxyl radical production might be the rate determining step.     

Data-based and model-based blockage diagnosis for stacked microchemical processes

One of the critical problems in the operation of microchemical processes is blockage in microchannels. Therefore, a process monitoring system which can detect and diagnose blockage is indispensable for effective and stable operation of microchemical processes. In the present research, two types of diagnosis systems, a data-based blockage diagnosis system (DB-BDS) and a model-based blockage diagnosis system (MB-BDS), are proposed. To realize efficient diagnosis for various degrees of blockage, the proposed DB-BDS uses the ratios of temperature differences between normal and abnormal operating conditions at one sensor to those at the other sensor. On the other hand, MB-BDS, which uses simple physical models of the process, diagnoses blockage by calculating the correlation coefficients between the prepared temperature distribution vectors and the actual temperature distribution vector when blockage is detected. The performance of the proposed systems is evaluated with their applications to a stacked microreactor. DB-BDS and MB-BDS are applied to various types of blockage, i.e., various locations and degrees. The results show that both DB-BDS and MB-BDS can diagnose the blockage location successfully even when blockage degree is less than 10%.     

Broadening of the effective temperature range for NO removal on Co·Pd-modified H-ZSM-5 catalyst by suppression of CH4 combustion

Broadening the effective temperature range (window) of NO removal on Co·Pd-modified H-ZSM-5 (Co/Pd/H-ZSM-5) in the presence of methane under an excess-oxygen condition was tried under the concept that the lack of the amount of methane occurred by CH₄ combustion at high temperature reduced NO conversion to N₂. The activity for NO removal of the catalyst at high temperature was improved due to suppression of methane combustion by the thermal treatment of Pd in a H₂-containing flow. Co/Pd/H-ZSM-5s with and without the thermal treatment of Pd showed different temperature windows for NO elimination. These different windows were then combined by a two-stage catalyst packing, in which Co/(Pd/H-ZSM-5)_red. and Co/Pd/H-ZSM-5 were placed in series, resulting in the broadening of the window. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation of Apatite Thin Films through rf-Sputtering from Calcium Phosphate Glasses

Apatite thin films of calcium phosphate were successfully prepared by rf-magnetron sputtering, followed by postannealing, from calcium phosphate glass targets with Ca/P atomic ratios of 0.6 to 0.75, much lower than the stoichio-metric value of 1.67 for hydroxyapatite. Using targets with low Ca/P ratios of 0.65 to 0.25, tricalcium and pyrocalcium phosphate thin films were obtained. The formation of these calcium phosphates phases was attributed to the phosphorus oxide losses during sputtering. H₂O vapor was effective in the formation of the apatite phase at high temperatures; apatite was the exclusive phase in the ambient H₂O, even when the target with the low Ca/P ratio of 0.4 was used. Based on phase stability at high temperatures, it was assumed that various kinds of apatites, such as stoichiometric and nonstoichiometric hydroxy- and Ca-deficient hydroxy-apatites were formed, depending on the composition of the glass targets.     

Development of nutation motors (improvement of pneumatic nutation motor by optimizing diaphragm design)

This article describes the improvement of a pneumatic nutation motor. Pneumatic nutation motors that are driven by diaphragm are expected to have bigger torque. In this report, refined design of the diaphragm is discussed. First, several different shapes of diaphragms are proposed and analyzed with nonlinear FEM. Second, a “bellows type” diaphragm is fabricated and built in the motor. Holding fixture for the diaphragm is also refined to improve its performance. Finally, torques of the new model and conventional model are compared, resulting in that the new model generates the torque 20 percent higher than that of the conventional model at any air pressure.     

QoE assessment of fairness in networked game with olfaction: influence of time it takes for smell to reach player

In this paper, we carry out QoE (Quality of Experience) assessment of fairness between players in a networked game with olfaction. In the assessment, we investigate the influence of the time it takes for a smell to reach a player on the fairness. As the networked game, we deal with a fruit harvesting game in which two players play in a 3D virtual space, and we change the time it takes for a smell to reach a player by generating constant delays at two terminals. As a result, for example, we illustrate that the fairness is hardly damaged when the constant delays are smaller than about 500 ms.     

Discrete-time observability for distributed parameter systems

The aim of this paper is to study the observability for systems described by first-order evolution equations and for those described by second-order evolution equations in the case of discrete-time observations. For the systems with a finite number of sensors we present necessary and sufficient conditions for observability. We show that these distributed parameter systems are never finite-step observable. We give the restricted sets of the initial-state spaces whose elements are N-step observable. We also investigate the relations between the systems with discrete-time observations and the systems with continuous-time observations from the viewpoint of observability Moreover, we see the essential difference between the parabolic case and the hyperbolic case.     

Dynamic shape control for a flexible beam

In this paper we discuss the dynamic shape control for a flexible beam such that even under unknown step disturbances, the shape of the beam will track the desired shape after a certain regulation time. In order to treat the case of point controls and point observations, we formulate the flexible beam by a second-order partial differential equation on a Hilbert space H^?1(0, 1). We apply the theory of multivariable tuning regulators to the dynamic shape control problem. Two kinds of methods will be proposed for the determination of an integral feedback gain matrix M. Simulation results will show the efficiency of the theory developed in this paper.     

Parameter identifiability for distributed parameter systems of hyperbolic type

In this paper we study questions regarding parameter identifiability for distributed parameter systems of hyperbolic type. The unknown parameters are input distribution functions. We consider the systems with continuous-time input-output data and the systems with discrete-time inputs-output data. For these systems we present the necessary and sufficient conditions for identifiability, in the case of a finite number of sensors. We investigate the relations between the continuous-time input-output systems and the discrete-time input-output systems from the viewpoint of identifiability. Moreover we give the sets of input distribution functions which are N-step identifiable, for the discrete-time input-output systems.