Theory and characteristics of novel variable reluctance 1X resolver

Although brushless resolvers have been used widely as angular position transducers, they are expensive due to their intricate construction, involving a rotary transformer to supply the exciting coils wound on the rotor poles with the current. It is shown theoretically in this paper that the resolver without rotary transformer or brushes can be realized by simple construction, which consists of the stator core with both 4-poles exciting windings and 2-poles output ones and the rotor core carrying no windings. In this resolver the rotor core has minimum gap at one side and a maximum gap at another side of the diameter. It is characterized by an outer surface form that makes the fluctuation part of gap permeance very in proportion to cos θ, where θ represents the angular position of a point in the air gap with respect to the origin on the rotor, the point of minimum air gap. The method determining the rotor form to embody the aforementioned gap permeance variation is also shown. It has been confirmed not only by simulation but also experiment that the 2-phase output voltages of a model designed based on the theory have sinusoidal waveforms with very small harmonic contents. Moreover, the rotor position detected by processing the output voltages through the conventional resolver/digital converter was within acceptable engineering accuracy.     

Are lebed’s magic angles truly magic?

We report high-resolution angle-dependent measurements of the Periodic Orbit Resonance (POR) effect in (TMTSF)₂ClO₄. We observe additional harmonic resonances that were not observed in previous studies. By measuring over a broad range of frequency, field, and field orientation, we find that all of the POR evolve from the Lebed magic angles observed in dc (ω=0) AMRO measurements. However, we find that the resonance angles vary with frequency in a manner that can easily be explained using a semiclassical model. This indicates that these angles are not ‘magic’ at frequencies on the order of the cyclotron frequency.     

Voltage Control of Static Var Compensator for a Remote System Interconnected by Long‐Distance AC Cables

The voltage variation in a remote system is large when the system is connected by long‐distance AC cables due to the cable capacitance. In Japan, the longest 54‐km 66‐kV AC submarine cable interconnection between the Kyushu mainland and Goto Islands was commissioned in 2005. It was requested to mitigate the voltage variation caused by switching off and on one circuit of the two circuits in the AC cables when a fault occurs. Since the conventional voltage control methods such as transformer tap changer or shunt capacitor and reactor banks are not sufficient because of their slow response time, a static var compensator (SVC) was installed on the Goto Islands. In such an application, an SVC control method should be developed so as not to override the existing voltage control systems. This paper describes the SVC control method developed for the Goto Islands AC interconnection project, which can be applied to similar situations. The effectiveness of the control method was verified by the results of effective value simulation and of field testing, which was implemented before the SVC was commissioned in 2007. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 19–30, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22337     

Performance Comparison of Circuits for Pole‐Mounted STATCOM Using SiC Devices

The recent years have seen an increasing trend in the cumulative installed capacity of distributed generators. As a result, voltage management may become difficult in existing power distribution systems in the future. A STATCOM (STAtic synchronous COMpensator) is a promising option for solving this problem because it can control reactive power rapidly and continuously. For a distribution system, STATCOM needs to be pole‐mounted to realize its low cost. However, a transformer for a STATCOM is large and heavy, and hence it is difficult to install a STATCOM on a distribution pole. We adopt a transformerless STATCOM to reduce STATCOM size and use SiC devices with low‐loss performance to obtain a more compact and efficient STATCOM. There are a large number of circuits available for a STATCOM, and there has been considerable research on performance comparisons among these circuits. However, these comparisons were drawn under different conditions, including switching frequency and level number for the circuits. In addition, these comparisons do not include the use of SiC devices. We made an equitable comparison for a 100 kVa pole‐mounted STATCOM using SiC devices. We discuss the performance and characteristics of each circuit in terms of efficiency and volume.     

Preparation of ultrafine polyurethane fiber web by laser‐electrospinning combined with air blowing

Thermoplastic polyurethane fiber webs were prepared using a laser‐heated electrospinning process combined with air blowing. The effect of spinning conditions such as air flow rate and air temperature on fiber diameter and molecular weight was investigated. Although the average fiber diameter decreased with increased air flow rate at each air temperature, the diameter increased when the air flow rate was >15 NL min^?1. In addition, the fiber was comparatively thicker with an increase in the air temperature. The variation in the fiber diameter tends to increase with the air flow rate, and a reduction in the molecular weight of the fiber by thermal degradation was suppressed. The thinnest and most uniform fiber with a diameter of 0.9 µm and a diameter coefficient variation of 15% was obtained at an air temperature of 25°C under an air flow rate of 15 NL min^?1. This fiber also had a minimum of decreased molecular weight. POLYM. ENG. SCI., 54:2605–2609, 2014. © 2013 Society of Plastics Engineers     

Synthesis of Ti-based bulk quasicrystal by shock compression

We attempted to produce a Ti₄₅Zr₃₈Ni₁₇ bulk icosahedral (i) quasicrystal by a shock compression technique, in which a single-stage powder gun discharges a flyer plate that consolidates the target powders. The results were also compared with those by a conventional hot-pressing. The powder mixtures for the shock compression were blended by two kinds of methods; that is, gently mixing in a vial, and mechanically alloying by a planetary ball mill. A large bulk i-phase sample, with a Ti₂Ni crystal phase, was synthesized from mechanically alloyed powders after shock compression at a higher flyer velocity, although the conventional hot-pressing at 3 MPa synthesized only the Ti₂Ni phase. For the gently mixed powders, no reaction occured even after shock compression. High-pressure and high-temperature produced during shock compression, and milling process were key factors to obtain the i-phase. The Vickers hardness and the wetting contact angle with pure water under an atmospheric pressure for the bulk sample containing the i-phase were about 7 GPa and about 70°, respectively.     

Caenorhabditis elegans has two isozymic forms, CE-1 and CE-2, of fructose-1,6-bisphosphate aldolase which are encoded by different genes

Two distinct types of cDNAs for fructose-1,6-bisphosphate (FBP) aldolase, Ce-1 and Ce-2, have been isolated from nematode Caenorhabditis elegans, and the respective recombinant aldolase isozymes, CE-1 and CE-2, have been purified and characterized. The Ce-1 and Ce-2 are 1282 and 1248 bp in total length, respectively, and both have an open reading frame of 1098 bp, which encodes 366 amino acid residues. The entire amino acid sequences deduced from Ce-1 and Ce-2 show a high degree of identity to one another and to those of vertebrate and invertebrate aldolases. The highest sequence diversity was found in the carboxyl-terminal region that corresponds to one of the isozyme group-specific sequences of vertebrate aldolase isozymes that play a role in determining isozyme-specific functions. Southern blot analysis suggests that CE-1 and CE-2 are encoded by different genes. Concerning general or kinetic properties, CE-2 is quite different from CE-1. CE-1 exhibits unique characteristics which are not identical to any aldolase isozymes previously reported, whereas CE-2 is similar to vertebrate aldolase C. These results suggest that CE-2 might preserve the properties of a progenitor aldolase with a moderate preference for FBP over fructose 1-phosphate (F1P) as a substrate, whereas CE-1 evolved to act as an intrinsic enzyme that exhibits a much broader substrate specificity than dose CE-2.     

Protective effect of arginine, leucine and preinjection of insulin on glutamate neurotoxicity in mice

The simultaneous intubation of 10-day-old mice with either 2.28 g/kg body weight arginine hydrochloride or 0.2 g/kg b.wt. leucine significantly reduced the number of necrotic neurons in the arcuate nucleus (AN) of the hypothalamus resulting from 2 g/kg b. wt. monosodium L-gultamate (MSG). The prior injection of 0.02 units per capita of insulin suppressed the MSG-induced lesions to an even great extent. These findings are believed to form a basis for the ineffectiveness of dietary MSG in producing hypothalamic lesions.     

Development of multianode photomultiplier tube

We have developed a multianode photomultiplier tube (MAPMT) which has a sensitive cathode diameter of 36 mm and an anode with 88 segments. The position sensitivity of the tube was studied by using light from a LED and scintillation light from a scintillation-fiber bundle. We observed particle tracks for the first time by using a single photomultiplier tube.     

Effects of light guides and optical filters for a high density lead glass counter

Effects of various light guides on energy resolution, position dependence of the output pulse and the hadron suppression factor were studied for a high density lead glass counter with particles of energies between 1 GeV and 16 GeV. The best hadron suppression factor was obtained for a configuration with a plastic light guide and a short wave cutoff filter at little expense to energy resolution. The energy resolution is worse at high energy and is dependent on the hit position of an incident particle for a BK7 light guide.