Predicting the Life Span of Dies Used for Soft Magnetic Core Motors

This paper describes a method of predicting the life span of the dies used in motor manufacture from soft magnetic composites (SMCs). In the present study, a clawtooth motor was used. The method involves performing a stress analysis of a die followed by fatigue testing of test pieces. In the analysis, the SMC was assumed to be in powder form and its yield function was derived by a simple method. In addition to the analysis, we describe a simpler and more effective method in which the properties of the SMC are treated as boundary conditions. In the fatigue tests, we used test pieces that simulated the shape and construction material of the die. To predict the life span of the die, we evaluate the SN diagram, which represents the relationship between the maximum stress and fatigue life with respect to the stress generated in the die. The life expectancy of a new die, which is about 100 cycles of use, is found to agree substantially with its actual life. Furthermore, we explain how to extend the life span of a die to the targeted life span, namely, more than 200,000 cycles of use, by changing its shape to reduce stress.     

Synthesis of ZnFe2O4 nanosized powders by pulsed wire discharge

Nanocrystalline zinc ferrite (ZnFe₂O₄) powders have been synthesized successfully by high-power short-pulse electric discharge of Fe and Zn wires in oxygen gas. The powders were characterized by X-ray diffraction and transmission electron microscopy (TEM). Mean size of the obtained particles determined by both BET and TEM was 12 to 56 nm depending on the oxygen pressure. X-ray analysis showed that the zinc ferrite spinel was clearly obtained. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(450), pp. 3–6, July–August, 2006.     

Evidence for Altered Phosphoinositide Signaling-Associated Molecules in the Postmortem Prefrontal Cortex of Patients with Schizophrenia

Phosphoinositides (PIs) play important roles in the structure and function of the brain. Associations between PIs and the pathophysiology of schizophrenia have been studied. However, the significance of the PI metabolic pathway in the pathology of schizophrenia is unknown. We examined the expression of PI signaling-associated proteins in the postmortem brain of schizophrenia patients. Protein expression levels of phosphatidylinositol 4-phosphate 5-kinase type-1 gamma (PIP5K1C), phosphatidylinositol 4-kinase alpha (PIK4CA, also known as PIK4A), phosphatase and tensin homolog deleted from chromosome 10 (PTEN), protein kinase B (Akt), and glycogen synthase kinase 3β (GSK3β) were measured using enzyme-linked immunosorbent assays and multiplex fluorescent bead-based immunoassays of the prefrontal cortex (PFC) of postmortem samples from 23 schizophrenia patients and 47 normal controls. We also examined the association between PIK4CA expression and its genetic variants in the same brain samples. PIK4CA expression was lower, whereas Akt expression was higher, in the PFC of schizophrenia patients than in that of controls; PIP5K1C, PTEN, and GSK3β expression was not different. No single-nucleotide polymorphism significantly affected protein expression. We identified molecules involved in the pathology of schizophrenia via this lipid metabolic pathway. These results suggest that PIK4CA is involved in the mechanism underlying the pathogenesis of schizophrenia and is a potential novel therapeutic target.     

Effect of nickel addition on the toughness of 18Cr-1 Mo stainless steels

The toughness of ferritic stainless steels has been thought to deteriorate due to carbide and nitride precipitation and also due to grain coarsening. The effect of martensite dispersion on the toughness of 18Cr–1 Mo stainless steel was studied by adding nickel up to 4%, by which the-loop was extended and an- transformation was introduced. To precipitate austenite homogeneously, proper thermomechanical processing was conducted: rapid hot-rolling without recrystallization in the temperature range just above the two-phase region, followed by precipitation treatment of austenite at the temperature of the two phase region. The ferrite single phase of grain size 100/gmm was developed by nickel addition up to 2%, and a microduplex structure composed of ferrite and martensite of 10m was developed by above 3%. The impact transition temperature in the ferritic single phase decreased remarkably only with 1 to 2% nickel addition and water quenching from solution treatment temperature. In the microduplex structure, the transition temperature decreased remarkably with 4% nickel addition and tempering treatment. Martensite has the effect of stopping the crack propagation, and the transition temperature depends mainly on the fracture facet size, which decreases with the amount of martensite.     

Facile preparation of a polysiloxane-based hybrid composite with highly-oriented boron nitride nanosheets and an unmodified surface

A facile technique was developed to fabricate polysiloxane-based hybrid composite films containing boron nitride (BN) nanosheets using a nanopulse-width electric field. BN nanosheets assumed anisotrophic alignment under the electric field, without requiring surface coating with metallic nano particles despite the wide band gap. BN was dispersed by sonication in a pre-polymer polysiloxane mixture. The homogeneous suspension was cast on a glass spacer and subjected to either a DC electric field or a nanopulse-width electric field before the mixture was cured through polymerization. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that BN nanosheets in the polysiloxane matrix were aligned with high anisotropy to the electric field direction, which was perpendicular to the film plane. The transmittance of the film samples, measured by UV–visible spectrometry, indicated that the composite, prepared using a nanopulse-width electric field manifested a significantly improved transmittance, compared with composites prepared without using the electric field.     

Facile orientation of unmodified BN nanosheets in polysiloxane/BN composite films using a high magnetic field

Composite films consisting of highly oriented boron nitride (BN) nanosheets in polysiloxane were fabricated without modifying the BN surface by applying a high magnetic field generated by a superconducting magnet. The hexagonal BN nanosheets were dispersed by sonication in a prepolymer mixture of polysiloxane. The homogeneous suspension was then cast on a polyamide spacer of microscale thickness and a magnetic field was applied before the mixture became crosslinked. The BN nanosheets in the polysiloxane were aligned with high anisotropy either parallel or perpendicular to the composite film plane depending on the magnetic flux direction. The fabricated composite films exhibited enhanced thermal conductivity by controlling the anisotropy of the BN nanosheets in the film. The mechanisms for rotation of BN nanosheets and heat diffusion across the composite film are discussed.     

Fabrication of CPA Salt Pill with Circulating Solution Method

We report results on fabrication of a Chromium Potassium Alum (CPA) salt pill. CPA is a typical paramagnetic salt used as refrigerant of Adiabatic Demagnetization Refrigerator (ADR) because of its low Curie point, 4–11 mK. We made an test model of CPA salt pill by fast crystallizing method, namely circulating solution between 36°C and 15°C. The crystallizing rate was 0.5 g h⁻¹, and 40 g of CPA crystal was obtained inside a stainless steel cylinder equipped with 160 copper wires. The cooling test was operated utilizing a commercial ADR system. We attached three thermometers and four heaters to the salt pill, in order to measure thermal conductance among different parts of the pill. It is confirmed that our salt pill was cooled down from B/T=4T/2 K to 64 mK at zero magnetic field. We suspect the cause of limiting the cooling temperature in the present level to be the dehydration of CPA, non-uniformity of magnetic field, and stainless steel of the pill which has large heat capacity below 0.1 K.      

Nanoparticle synthesis of transition-metal borides by pulsed discharge of compacted powder

In this study, boride nanoparticles were synthesized via a low-cost and simple pulsed discharge of compacted crystalline and amorphous B micron-sized powders for the first time. Borides of Ti, Mo, W, and Zr were chosen for synthesis experiments. The as-synthesized powders were spherically shaped and smaller than 100 nm. X-ray diffraction patterns indicated the presence of several minor phases in each boride powder in addition to a single main-phase boride. Specifically, the main phases were TiB₂, MoB₂, WB₄, and ZrB₂ for borides of Ti, Mo, W, and Zr, respectively. Energy-dispersive spectroscopy (EDS) indicated the presence of B and metal in almost all particles of every sample. The observed particles usually exhibited a two-part structure: a boride phase and B. Small amounts of C, Fe, Cr, and Ni were detected by EDS; however, the contents of Fe, Cr, and Ni were substantially reduced after improvements to the experimental setup.     

128×128 three-dimensional MEMS optical switch module with simultaneous optical path connection for optical cross-connect systems

A 128×128 three-dimensional MEMS optical switch module and a switching-control algorithm for high-speed connection and optical power stabilization are described. A prototype switch module enables the simultaneous switching of all optical paths. The insertion loss is less than 4.6 dB and is 2.3 dB on average. The switching time is less than 38 ms and is 8 ms on average. We confirmed that the maximum optical power can be obtained and optical power stabilization control is possible. The results confirm that the module is suitable for practical use in optical cross-connect systems.     

High‐Efficiency Motors Using Soft Magnetic Cores

We have developed a small and highly efficient axial gap motor whose stator core consists of a soft magnetic core. First, the loss sensitivities to various motor design parameters were evaluated by magnetic field analysis. Low sensitivity to the pole number and core dimensions ( ? 2.2 dB) was found for the total loss, which is the sum of the copper loss and the iron losses in the stator core and the rotor yoke. From this we concluded that to improve the motor efficiency, it is essential to reduce the iron loss in the rotor yoke and to minimize the other losses. With this in mind, a prototype axial gap motor was manufactured and tested. The motor has four poles and six slots. The motor is 123 mm in diameter and the axial length is 47 mm. The rotor has parallel magnetized magnets and a rotor yoke with magnetic steel sheets. The maximum measured rotor efficiency is 93%. This value roughly agrees with the maximum calculated efficiency of 95%.