Control Model for Large‐Sized Gantry Type Linear Motor Slider

At present, many industrial carrier devices utilize linear motor sliders. However, a heavier load requires a linear motor (which is an example of a direct drive device) to get higher power, compared with a rotary motor with a ball screw slider (which is an example of an indirect drive device). In order to obtain higher power at a lower cost, a linear slider with multiple motors can be utilized, for example, a gantry type linear motor slider. Moving the gantry type slider requires two linear motors that are set up in parallel to enable synchronization control. Some conventional synchronization control methods have been proposed for the parallel twin linear slider; however, a large‐scaled gantry type linear motor slider has two unique problems: mechanical distortion caused by the limitations of installation environment and coupling caused by joints with low stiffness. This paper proposes a control model to solve these problems, and an identification method of each parameter. Furthermore, the effectiveness of the control model is verified by comparison with simulation results and experimental results.     

Performance Evaluation of Lithium‐Ion Batteries on Small Electric Bus

We evaluate performance of lithium‐ion batteries on the small electric bus, conducting tests of cell and battery pack using discharge/charge machine. We suggest the test item on distinction between good and bad of a battery. In the discharge/charge cycle tests of cell at environmental temperature (25 °C), the relative capacity was 60% at 10,000 cycles. In the discharge capacity test of battery packs on the small electric bus, the relative capacity maintained more than 90% in progress for approximately 900 days. Finally, based on these results, we analyzed about influence factor on a battery discharge capacity.     

Manufacturing and Control of a Variable Magnetic Flux Motor Prototype with a Mechanical Adjustment Method

A new structure and control method for a variable magnetic flux motor (VMFM) is proposed to achieve a high‐efficiency electric vehicle (EV) motor drive under a wide range of conditions. A VFMF prototype that was designed by considering the loss was manufactured and evaluated in an experiment. The prototype demonstrated low iron loss and sufficient max torque. Thus, the prototype can provide a high‐efficiency drive with low output, which is frequently the case for EVs. Map control enables a wide phase angle for the vector‐control drive of the VMFM under a changing magnetic flux. Thus, the VMFM provides a high‐efficiency drive under a wide range of conditions.     

Preparation and Thermal Properties of Dense Polycrystalline Oxyhydroxyapatite

Solution-grown crystals of hydroxyapatite were sintered into polycrystalline oxyhydroxyapatite bodies, using the range 1050 to 1450°C. The heat capacity, thermal diffusivity, and thermal conductivity of the sintered bodies were measured by the laser flash method at 130–1000 K. The sintered bodies were 94.4 to 99.4% of theoretical density and 0.8 to 12 μm in grain size. Sintering is accompanied by grain growth and by vacancy formation and cell contraction due to thermal dehydration. Typical values of the heat capacity, thermal diffusivity, and thermal conductivity at room temperature are 0.73 J/g K, 0.0057 cm²/s and 0.013 J/s cm K, respectively. Low-temperature thermal conductivity increased with increasing temperature, similarly to that of amorphous solids. This odd behavior is discussed in terms of phonon mean free path.     

Mechanism of inactivation of heat-tolerant spores of Bacillus stearothermophilus IFO 12550 by Rapid Decompression

The effect of three rapid decompression methods to clear the mechanism of inactivation of heat tolerant spores of Bacillus stearothermophilus IFO 12550 was investigated. Pressurization of the spores at 200 MPa and 75°C for 60 min caused a kill of 10⁴ CFU/mL by the link-motion system but the nonrotational rod valve and E.G. seal methods gave a kill of about 10³ CFU/mL. Sterilization was due to the physical breakdown of spore coat, and was induced by its physical permeability of water at high pressure and temperature. Rapid decompression by the link-motion system at 200 MPa decreased the D-value of the spores from 3000 min (100°C, one atmosphere) to 6 min, 11 min, and 17 min at 95, 85, and 75°C, respectively.     

Microstructural development with crystallization of hexagonal boron nitride

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Lead Zirconate Titanate Film Formation Technology with Use of Spray Coating Method

This paper presents a three-dimensional microfabrication and integration technology for MEMS smart materials that utilizes a spray coating method. Spray coating is shown to be most effective for additional deposition on non-planar surfaces. PZT films were formed both on flat and uneven surfaces at a thickness of about 1μ m. Perovskite structures were formed with suitable heat treatment and ferroelectric P-E hysteresis loop was also obtained. This paper is the first report from our group and other researchers on the deposition of smart materials for MEMS using a spray coating method. Spray coating has been proposed as an effective three-dimensional coating method which can be used to deposit piezoelectrics, pyroelectrics, magnetics, etc. for sensors and actuators. The hydrophilic and hydrophobic properties between the substrate surface and ejected liquid are most essential process factors in the spray coating method for improving the film growth conditions.     

Properties of Space Charge Distributions and Conduction Current in XLPE and LDPE under DC High Electric Field

Space charge behavior and conduction current in polyethylene under dc stress were investigated. One of the reasons for the different breakdown property in cross‐linked polyethylene (XLPE) from that in low‐density polyethylene (LDPE) may be based on the existence of cross‐linking by‐products in XLPE. Furthermore, a thermal history in cross‐linking process for XLPE may also cause of the difference. It is generally accepted that the existence of the cross‐linking by‐products increase the conduction current in XLPE under dc stress. It is also said that an anneal treatment in air atmosphere may affect to the electrical properties under dc stress. Therefore, we investigated the effect of the cross‐linking by‐products and the anneal treatment on space charge behavior and conduction current in polyethylene under dc stress. In our research, it is thought that the increasing dissipation power in XLPE is the cause of the breakdown in it under dc stress. Therefore, to calculate the dissipation power in the bulk of test sample, we measured the space charge distribution and the external circuit current simultaneously. Based on the results, we discussed the reason of the difference of the space charge properties in XLPE and LDPE focusing on the cross‐linking by‐products and the oxidation of the test samples.     

Synthesis of Magnetically Intensified Aluminosilicate

Intensification of magnetic susceptibility of the zeolite ensures not only quick and reliable separation of the zeolite from waste medium by using a magnetic separation but also efficient micro-wave heating of the zeolite.Thus,reinforcement of magnetic susceptibility of the zeolite has been attempted.In this study,a composite material has been synthesized by adding magnetite during a synthesis process of the zeolite.And the composite was evaluated by using XRD and SEM.It was composed of zeolite and magnetite.And,its shape was polygonal with a few micrometers size under the synthesis time of 4 weeks.Its magnetization in magnitude was about 400 times larger than that of the normally synthesized zeolite.And the mass ratio of the zeolite and the magnetite in the synthesized material was estimated at about 7.8:1.