Application of virtual machine technology to real-time mapping of Thomson scattering data to flux coordinates for the LHD

This paper presents a system called “TSMAP” that maps electron temperature profiles to flux coordinates for the Large Helical Device (LHD). Considering the flux surface is isothermal, TSMAP searches an equilibrium database for the LHD equilibrium that fits the electron temperature profile. The equilibrium database is built through many VMEC computations of the helical equilibria. Because the number of equilibria is large, the most important technical issue for realizing the TSMAP system is computational performance. Therefore, we use multiple personal computers to enhance performance when building the database for TSMAP. We use virtual machines on multiple Linux computers to run the TSMAP program. Virtual machine technology is flexible, allowing the number of computers to be easily increased. This paper discusses how the use of virtual machine technology enhances the performance of TSMAP calculations when multiple CPU cores are used.     

Flow characteristics of rectangular underexpanded impinging jets

In this paper, the flow fields of underexpanded impinging jet issued from rectangular nozzles of aspect ratio 1, 3 and 5 are numerically and experimentally studied. Two dimensional temperature and pressure distributions are measured by using infrared camera and the combination of a pressure scanning device and a stepping motor, respectively. The variation of the stagnation pressure on the impinging plate reveals that a hysteretic phenomenon exists during the increasing and decreasing of the pressure ratio for the aspect ratio of 3.0 and 5.0. It is also found that the nozzle of aspect ratio 1.0 caused the largest total pressure loss pc / p0 = 0.27 at the pressure ratio of p0 /pb = 6.5, where pc is the stagnation center pressure on the wall, p0 the upstream stagnation pressure, pb the ambient pressure. The other two nozzles showed that the pressure loss pc /p0 =0.52 and 0.55 were achieved by the nozzles of the aspect ratio 3,0 and 5.0, respectively. The comparison between the calculations and experiments is fairly good, showing the three dimensional streamlines and structures of the shock waves in the jets. However, the hysteresis of the pressure variations observed in the experiments between the pressure ratio of 3.5 and 4.5 cannot be confirmed in the calculations.     

Lithium ion secondary batteries; past 10 years and the future

Technologies of lithium ion secondary batteries (LIB) were pioneered by Sony. Since the introduction of LIB on the market first in the world in 1991, the LIB has been applied to consumer products as diverse as cellular phones, video cameras, notebook computers, portable minidisk players and others. Years of assiduous efforts and researches to improve LIB performances enabled LIB to play a leading role in the portable secondary battery market. In this article, the past 10 years’ technological achievement is traced and future possibilities are discussed.     

Modeling the phase partitioning behavior of gas tracers under geothermal reservoir conditions

A model of the liquid-vapor phase partitioning behavior of low concentrations of gas tracers in water at geothermal temperatures and pressures is presented. This model uses Henry's coefficient to describe the variation of the gas tracer solubility with temperature and pressure. A new method is described for the determination and representation of Henry's coefficients. The method uses experimentally determined values of Henry's coefficient and a theoretically predicted value of behavior at the critical point of water to provide data that can be fitted by a semi-empirical correlation. No assumptions regarding ideal behavior are necessary. The semi-empirical correlation is a modified version of that presented by Harvey, A. (1996. Semiempirical correlation for Henry's constants over large temperature ranges. American Institute of Chemical Engineers Journal 42(5), 1491-1494) and better accounts for high temperature and non-ideal behavior. Sets of model coefficients are given for a range of possible gas tracers. The resulting phase partitioning model is simple and may be easily implemented in a numerical geothermal simulator. The use and behavior of the model is illustrated by its application to a number of idealised test problems.     

Characterization of strong solid bases by test reactions

The isomerization of 2,3-dimethylbut-1-ene and the decomposition of 2-methyl-3-butyn-2-ol were carried out over a number of solid base catalysts. Rubidium amide supported on alumina was the most active for the isomerization, which proceeds almost to the equilibrium in 10 min at 201 K. The isomerization is a very useful test reaction for determining the relative activities of very strong solid bases. However, weak solid bases such as K⁺-exchanged Y zeolite are totally inactive for the isomerization. The decomposition of 2-methyl-3-butyn-2-ol is a suitable reaction to discriminate acidic and basic catalysts. It can be also used for estimating the basic property of weak bases such as lithium hydroxide supported on alumina. However, caution is necessary for strongly basic catalysts because of strong adsorption of the products, acetylene and acetone.     

Effect of material processing on fatigue of FPC rolled copper foil

The effects of rolling strain during final cold reduction and of post-anneal grain size prior to final reduction on fatigue behavior of the rolled copper foil after recrystallization anneal were examined. The fatigue property was characterized by the bending/unbending fatigue tests. Low rolling strain and large grain size prior to final rolling improved the low-cycle fatigue life due to increase in the ductility of material. High rolling strain and small grain size prior to final rolling improved the high-cycle fatigue presumably due to highly enhanced cube texture.     

Approximate analysis of traffic congestion in AGV system

This paper deals with a merging section of the Automated Guided Vehicle system under a time limit for merging. Near the merging section, one flow of traffic must form a queue to avoid collision of vehicles. The vehicle behavior is analyzed using approximate analysis with the Markov chain approach; the analysis is based on an idealized model. It is important to consider the behavior of traffic at merging sections in the design of the overall AGV system, and also in the realization of the system. We derive the average queue length and the average waiting time by using recurrence. The relationship between queuing delay and traffic density is examined. Therefore, we can make quantitative analysis of the behavior of traffic. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(2): 36–45, 1997     

Autonomous decentralized system for torque control of high‐power permanent magnet synchronous motor

An autonomous decentralized system (ADS) for the control of a high‐power permanent magnet synchronous motor (PMSM) presented in this paper. The system decentralizes a centralized control system into several autonomous subsystems. Thus the power supply and power electronic devices of the control system can be replaced by smaller ones, thereby obtaining better fault tolerance of the system. The subsystems are connected only through the data field, which, in this paper consists of feedback elements and communication modules. This structure enables the autonomous controllability and autonomous coordinability of the system. The mathematical model of the PMSM with decentralized stator coils is proposed. This model takes into account the self‐ and mutual inductance of the coil, as well as the effect of the stator slot‐pitch angle. In addition, an autonomous algorithm for the torque control of the PMSM with decentralized stator coils is proposed, and the fault‐tolerance design is developed. Experimental results of the torque control and fault‐tolerance control confirm the validity of the proposed system. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Distribution of electric field strength around a large-scalecharged particle cloud

To investigate an electrical discharge occurring from or in a space-charge cloud, a large-scale charged particle cloud was formed by using a cloud generator consisting of a blower and corona charger. The distribution of the electric field strength around a charged particle cloud has been investigated to determine the behavior of charged particles. The soil-conditioning particles were charged by corona charging and blown by high-speed air flow in a test room, 5 m wide, 10 m long, and 3 m high. The average charge-to-mass ratio of the particles blown by this method was 170 μC/kg. The space-charge density of the cloud was calculated at the order of 10 μC/m³ from the electric field strength outside of the cloud. While the electric field strength at the outside of the cloud increased up to 52 kV/m within 2 m downstream from the cloud generator, it decreased below 25 kV/m farther than 2 m away from the cloud generator due to dispersion of charged particles. The change in the electric field strength due to dispersion of charged particles can be qualitatively explained by a simple cloud model. The velocity of charged particles transported by air flow and mobility of charged particles are found to be effective factors increasing the electric field strength around the large-scale charged particle cloud     

A maximum neural network algorithm for route selection problems in multihop radio networks

In a multihop radio network, packets are transmitted from course nodes to destination nodes by activating several links between nodes. Each node can either send a packet to, or receive a packet from, at most one of its adjacent nodes simultaneously. To minimize the transmission time for given requests, the problems must be solved by selecting a transmission route for each request (the routing problem) and by finding a link activation schedule (the link activation problem). The routing problem is decomposed into two subproblems: the candidate extraction problem and the route selection problem. In this paper, we propose a neural network algorithm using the maximum neuron model for the route selection problem. We verify through simulations that our algorithm finds better solutions in a shorter time than the existing algorithms. We also probe the NP‐hardness of this problem. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 78–86, 1999