Research on Liquid Management Technology in Water Tank and Reactor for Propulsion System with Hydrogen Production System Utilizing Aluminum and Water Reaction

High pressure hydrogen produced by aluminum and water reaction is considered to be applied to space propulsion system. Water tank and hydrogen production reactor in this propulsion system require gas and liquid separation function under microgravity condition. We consider to install vane type liquid acquisition device (LAD) utilizing surface tension in the water tank, and install gas-liquid separation mechanism by centrifugal force which swirling flow creates in the hydrogen reactor. In water tank, hydrophilic coating was covered on both tank wall and vane surface to improve wettability. Function of LAD in water tank and gas-liquid separation in reaction vessel were evaluated by short duration microgravity experiments using drop tower facility. In the water tank, it was confirmed that liquid was driven and acquired on the outlet due to capillary force created by vanes. In addition of this, it was found that gas-liquid separation worked well by swirling flow in hydrogen production reactor. However, collection of hydrogen gas bubble was sometimes suppressed by aluminum alloy particles, which is open problem to be solved.     

Difference Frequency Generation of 5-18 mum in a AgGaSe(2) Crystal

Mid-infrared radiation in the 5-18-mum range has been obtained by difference frequency generation in a AgGaSe(2) crystal by pumping with the output of a type I LiNbO(3) optical parametric oscillator (OPO). Here we suggest the use of a LiTaO(3) retarder to achieve an orthogonal state of polarization between OPO outputs that are necessary for efficient pumping of a AgGaSe(2) crystal. Several tens of kilowatts of peak power near 8 mum and continuously tunable operation in the above range have been obtained.     

High-efficiency diffractive micromachined chopper for infrared wavelength and its application to a pyroelectric infrared sensor

We have developed a diffractive micromachined chopper (DMC) for an IR wavelength of ~10 mum. This device operates mechanically by movable reflection grating beams. It modulates the diffraction efficiency by controlling the displacement of grating beams by an electrostatic force. For a CO(2) laser beam, a high modulation efficiency of 84% with an -0.8-dB small insertion loss was obtained by detecting 0th-order diffracted light. A novel pyroelectric IR microsensor with a DMC and a diffractive multilevel Si microlens was proposed and it demonstrated the detection of human existence.     

Access concentration detection in click logs to improve mobile Web-IR

Effective ranking algorithms for mobile Web searches are being actively pursued. Due to the peculiar and troublesome properties of mobile contents such as scant text, few outward links, and few input keywords, conventional Web search techniques using bag-of-words ranking functions or link-based algorithms are not good enough for mobile Web searches. Our solution is to use click logs to clarify access-concentrated search results for each query and to utilize the titles and snippets to expand the queries. Many previous works regard the absolute click numbers as the degree of access concentration, but they are strongly biased such that higher-ranked search results are more easily clicked than lower-ranked ones. Therefore, it is considered that only higher-ranked search results are access-concentrated ones and that only terms extracted from them can be used to expand a query. In this paper, we introduce a new measure that is capable of estimating the degree of access concentration. This measure is used to precisely extract access concentration sites from many search results and to expand queries with terms extracted from them. We conducted an experiment using the click logs and data from an actual mobile Web search site. Results obtained show that our proposed method is a more effective way to boost the search precision than using other query expansion methods such as the top K search results or the most-often-clicked search results.     

A small-gain condition for iISS of interconnected retarded systems based on Lyapunov-Krasovskii functionals

This paper considers interconnected retarded nonlinear systems. Integral input-to-state stable subsystems and the construction of Lyapunov-Krasovskii functionals for their interconnections are focused on. Both discrete and distributed time-delays in the subsystems and the communication channels are covered. This paper provides a sufficient small-gain type condition for the stability of the interconnected systems with respect to external inputs in the framework of Lyapunov-Krasovskii functionals. Global asymptotic stability is addressed as a special case which deals with time-varying delays in communication channels effectively.     

Molecular mechanics and molecular orbital simulations on specific interactions between peroxisome proliferator-activated receptor PPARalpha and plasticizer

Peroxisome proliferator-activated receptor α (PPARα) has various physiological functions such as lipid and glucose metabolism, inflammation and fibrosis in living organisms. Many types of ligand molecules such as phthalate and adipate esters control these physiological functions. In the present study, to elucidate the dependence of PPARα properties on ligand binding, we investigated stable structures and electronic properties for the complexes of PPARα and phthalate as well as adipate esters, which are used as a plasticizer, by molecular simulations based on molecular mechanics and molecular orbital methods. Furthermore, to elucidate the influence of these esters in vivo, we injected them into male mice and observed the change in the expression of PPARα-related enzymes. The comparison between the calculated and observed results indicates that the change in the expression has a correlation with the size of energy gaps between highest occupied and lowest unoccupied molecular orbitals of the complexes with mouse PPARα and esters.     

Realization of flock behavior by using Tau-margin

Recently autonomous robot that is designed based on biological mechanism has attracted much attention. In this paper we focus on mechanism of timing control which is studied in ecological psychology, and we apply it for controlling of multi mobile robot. Simulations have been conducted and various flock behaviors have been realized. In addition, we have confirmed that by using two leader robots, separation of flock is also possible. We can conclude that it is possible to realize flock behaviors by using the timing control without information of distance. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Peer-to-peer sensor network system for a school temperature measurement system

In this paper, we propose the technique of sensor data mining by the peer-to-peer (P2P) network. The mechanism that it is possible to share on the P2P network is considered by receiving information from the sensor by the P2P application. A searching request for a sensor unit and mining the sensor data occurs on the P2P application. We applied the proposed technique to a school environment measurement system. In this system, sensor units are arranged on campus and a user can measure a room’s temperature and humidity. The temperature sensor and the humidity sensor are implemented in a microcomputer board that can connect to the Internet, and we define the microcomputer board as a sensor unit. We construct the P2P sensor network on which a PC accesses the sensor unit and the P2P application on its PC uploads on the P2P network. The P2P network can disclose sensor information after more advanced processing is given by thinking as a P2P application and not a sensor unit, but on the sensor unit and the PC. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Adaptive immunity based reinforcement learning

Recently much attention has been paid to intelligent systems which can adapt themselves to dynamic and/or unknown environments by the use of learning methods. However, traditional learning methods have a disadvantage that learning requires enormously long amounts of time with the degree of complexity of systems and environments to be considered. We thus propose a novel reinforcement learning method based on adaptive immunity. Our proposed method can provide a near-optimal solution with less learning time by self-learning using the concept of adaptive immunity. The validity of our method is demonstrated through some simulations with Sutton’s maze problem. This work was present in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Three-dimensional parallel Turing machines

Informally, the parallel Turing machine (PTM) proposed by Wiedermann is a set of identical usual sequential Turing machines (STMs) cooperating on two common tapes: storage tape and input tape. Moreover, STMs which represent the individual processors of a parallel computer can multiply themselves in the course of computation. On the other hand, during the past 25 years or so, automata on a three-dimensional tape have been proposed as computational models of three-dimensional pattern processing, and several properties of such automata have been obtained. We proposed a three-dimensional parallel Turing machine (3-PTM), and dealt with a hardware-bounded 3-PTM whose inputs are restricted to cubic ones. We believe that this machine is useful in measuring the parallel computational complexity of three-dimensional images. In this article, we continue the study of 3-PTM, whose inputs are restricted to cubic ones, and investigate some of its accepting powers. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007