Harmonic compensation using a synchronous machine with resonantfield circuits

This paper deals with a harmonic compensation method using a synchronous machine with resonant field circuits. Harmonics have become one of the major problems in power systems and a lot of methods of harmonic suppression have been studied. The authors have proposed a new method of harmonic suppression using a synchronous machine excited with the 6th harmonic current. This paper shows that armature inductances for the 5th or 7th harmonics decrease when the field circuits are connected to capacitors resonating at the 6th harmonic. The variations of armature impedances are explained theoretically by Park's equations. The optimal capacitances are selected so as to resonate with field inductances for the short-circuited armature. The experiments to suppress the 5th and 7th harmonics using the synchronous machine are successful     

Catalytic oxidation of isobutane to methacrylic acid with molecular oxygen over activated pyridinium 12-molybdophosphate

Isobutane was catalytically oxidized to methacrylic acid with molecular oxygen above 300°C over 0 crystalline particles of pyridinium 12-molybdophosphates which were activated by heat-treatment under a nitrogen stream up to 420°C. During the treatment two third of pyridine were released from the sample and one third remained accompanied by the formation of orthorhombic structure. It was proved by IR studies that the catalyst became a reduced state by this treatment. The reduced state was highly stable even under catalytic oxidation conditions with molecular oxygen. 50% selectivity to methacrylic acid and 22% to acetic acid were achieved at 22% conversion of isobutane. The highly stable reduced state and structure of the activated heteropolymolybdophosphate catalyst seem to be responsible for the high activity for isobutane oxidation and high selectivity to methacrylic acid formation. This revised version was published online in July 2006 with corrections to the Cover Date.     

A real time sectional image measuring system using timesequentially coded grating method

A real-time sectional image measuring system is developed using the time-sequentially-coded grating method, and its application to automatic 3D image data measuring systems is studied. A PLZT electron shutter array is used to project time-sequentially-coded grating patterns on the object. The sectional image is calculated from deformed grating images which are picked up by a TV camera. This system takes about 530 ms to project the 100-slit time-sequentially-coded grating patterns and about 30 ms to calculate one sectional image     

RETRACTED ARTICLE: Single-Phase <Emphasis Type="Italic">β</Emphasis>-Zn<Subscript>4</Subscript>Sb<Subscript>3</Subscript> Prepared by a Mechanical Grinding Method

Single-phase β-Zn₄Sb₃ materials were prepared by mechanical grinding (MG). Source materials for the Zn₄Sb₃ ingots were prepared using three different processes after the direct melting of constituent elements. In process 1, the ingot was obtained by quenching the melt in water within an evacuated quartz ampoule. In process 2, the ingot was heat-treated for 100 h at 723 K after process 1. In process 3, the ingot was heat-treated for a total of 200 h in two stages at 723 K and 673 K after process 1. The resultant ingots were mechanically ground and sintered at 623 K by hot pressing. The sintered materials were characterized by x-ray diffraction, differential thermal analysis (DTA), and thermoelectric property measurements. The thermal conductivity of the sintered materials was 0.88 W m⁻¹ K⁻¹ at room temperature, being slightly lower than that reported for the materials prepared by a conventional method. Results indicate that the dimensionless figure of merit of the single-phase β-Zn₄Sb₃ ranged from 1.06 to 1.31 at 573 K.     

Photoswitching of diarylethene using bisazomethine dye

The photoswitching behavior of a diarylethene/glass/bisazomethine (DE/glass/BAE) three-layered structure was investigated. Upon UV light irradiation of 300 nm, DE in the three-layered structure was isomerized by a cyclization photochromic reaction and its color changed from red to deep red. BAE is a blue–violet compound with strong absorption in the region from 400 to 600 nm and fluorescence from 550 to 700 nm. When UV radiation having a wavelength of 300 nm was irradiated on the BAE layer, DE underwent a cycloreversion photochromic reaction, and its color changed from deep red to red due to fluorescence from BAE at 604 nm. Exposure of the BAE layer to visible light did not induce the decoloration of DE because visible light induces the cycloreversion of DE was absorbed by BAE. We demonstrated that DE/glass/BAE three-layered structure has a potential application for photoswitching using a single UV light source.     

Ultimate strength of compressed stiffened plates and minimum stiffness ratio of their stiffeners

A theoretical investigation into the effectiveness of a stiffener against the ultimate strength of a stiffened plate is carried out. Series of the buckling analyses, the elastic large deflection analyses and the elastic-plastic large deflection analyses are performed by the analytical method and the finite element method on the stiffened plate under thrust. Experiments are also carried out on the stiffened plate under thrust to confirm the theoretical results.On buckling of a stiffened plate, it is well known that ther exxists a minimum stiffness ratio of a stiffener to the plate, $\text{λ}{}^{\mathrm{B}}{}_{\min }$, which gives the maximum limiting value of the buckling strength. Concerning the ultimate strength it was confirmed that there exists a significant stiffness ratio of a st stiffener to the plate, $\text{λ}{}^{\mathrm{U}}{}_{\min }$ similar to $\text{λ}{}^{\mathrm{B}}{}_{\min }$ for the buckling strength.It was also found that there are three typical collapse modes for the stiffened plate under thrust, that is: (1) MODE OO, overall collapse after overall buckling; (2) MODE LO, overall collapse after local buckling; (3) MODE LL, local collapse after local buckling.Approximatelmethods are proposed to evaluate the ultimate strength and $\text{λ}{}^{\mathrm{U}}{}_{\min }$ of a multi-stiffened plate under thrust.The effects of initial imperfections such as welding residual stresses and initial deflection on ultimate strength and $\text{λ}{}^{\mathrm{U}}{}_{\min }$ of a stiffened plate under thrust are also discussed.     

High density packaging technology ultra thin package & new tab package

As electronic devices become more highly integrated, the demand for small, high pin count packages has been increasing. We have developed two new types of IC packages in response to this demand. One is an ultra thin small outline package (TSOP) which has been reduced in size from the standard SOP and the other, which uses Tape Automated Bonding (TAB) technology, is a super thin, high pin count TAB in cap (T.I.C.) package. In this paper, we present these packages and their features along with the technologies used to improve package reliability and TAB. Thin packages are vulnerable to high humidity exposure, especially after heat shock.1 The following items were therefore investigated in order to improve humidity resistance: (1) The molding compound thermal stress, (2) Water absorption into the molding compound and its effect on package cracking during solder dipping, (3) Chip attach pad area and its affect on package cracking, (4) Adhesion between molding resin and chip attach pad and its affect on humidity resistance. With the improvements made as a result of these investigations, the reliability of the new thin packages is similar to that of the standard thicker plastic packages.