低压小功率风力直驱笼型异步发电机的设计

分析应用于无线通信基站的风力发电机性能的特殊要求,结合实例给出异步风力发电机的设计指标;总结异步电机电动和发电2种工作状态下的异同点,对比异步电动机的设计程序,提出低压小功率风力直驱笼型异步发电机的设计方法;并运用电磁设计的计算机辅助软件MathCAD,验证了设计方法的合理性.     

Reconstruction of the Front End Gland of the Intermediate-Pressure Cylinder of the K-300-240 Turbine at the Konakovskaya GRÉS Using Mathematical Modeling

In order to raise the reliability of operation of the system of end glands of K-300-240 turbines at the Konakovo State Regional Power Plant (Konakovskaya GRÉS), the system for feeding steam to the end glands of high-pressure and intermediate-pressure cylinders has been updated. The updating included reconstruction of chimneys at the suggestion of the Komtek-Énergoservis Co. and feeding of cooling steam to the zone of the third compartment of the front end gland of the intermediate-pressure cylinder. The measures taken increased the reliability of operation of the system of turbine glands, eliminated oil watering due to steaming, and reduced the temperature deformations of chimney gland yokes.     

Identification of Volatile Synomones, Induced by Nezara viridula Feeding and Oviposition on Bean spp., That Attract the Egg Parasitoid Trissolcus basalis

Bean plants (Vicia faba L. and Phaseolus vulgaris L.) damaged by feeding activity of Nezara viridula (L.) (Heteroptera: Pentatomidae), and onto which an egg mass had been laid, produced volatiles that attracted the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae). Extracts of volatiles of broad bean and French bean plants induced by adults of N. viridula as a result of their feeding activity, oviposition activity, and feeding and oviposition activity combined were analyzed by gas chromatography-mass spectrometry (GC-MS), and tested in Y-tube olfactometer bioassays as attractants for T. basalis females. In extracts from undamaged leguminous plants, green-leaf volatiles were absent or scarcely detected, and monoterpenes and sesquiterpenes were present at trace levels. No significant differences were detected in the profiles of volatiles of undamaged plants, and undamaged plants on which bugs were allowed only to lay eggs. In contrast, feeding and oviposition by adults of N. viridula induced in both leguminous plants a significant increase in terpenoids such as linalool, (E)-beta-caryophyllene, (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, and (3E)-4,8-dimethyl-1,3,7-nonatriene, which was induced only in French bean plants. Quantitative comparisons revealed increased levels of (E)-beta-caryophyllene in extracts from feeding-damaged plants with N. viridula egg masses compared to feeding-damaged plants without egg masses. In Y-tube olfactometer bioassays, T. basalis females were attracted by extracts of both leguminous plants only when N. viridula adults were allowed to feed and oviposit upon them. Fractionation of extracts of volatiles from broad bean plants with N. viridula feeding damage and egg masses yielded two fractions. but only the fraction containing (E)-beta-caryophyllene was attractive to the egg parasitoid. These findings indicate that N. viridula feeding and oviposition induce leguminous plants to produce blends of volatiles that are characterized by increased amounts of (E)-beta-caryophyllene, and these blends attract female T. basalis. The role of (E)-beta-caryophyllene as a potential synomone for T. basalis is discussed.     

Querying high-dimensional data in single-dimensional space

In this paper, we propose a new tunable index scheme, called iMinMax( ), that maps points in high-dimensional spaces to single-dimensional values determined by their maximum or minimum values among all dimensions. By varying the tuning knob, , we can obtain different families of iMinMax structures that are optimized for different distributions of data sets. The transformed data can then be indexed using existing single-dimensional indexing structures such as the B ⁺ -trees. Queries in the high-dimensional space have to be transformed into queries in the single-dimensional space and evaluated there. We present efficient algorithms for evaluating window queries as range queries on the single-dimensional space. We conducted an extensive performance study to evaluate the effectiveness of the proposed schemes. Our results show that iMinMax( ) outperforms existing techniques, including the Pyramid scheme and VA-file, by a wide margin. We then describe how iMinMax could be used in approximate K-nearest neighbor (KNN) search, and we present a comparative study against the recently proposed iDistance, a specialized KNN indexing method.Received: 21 May 2000, Revised: 14 March 2002, Published online: 8 April 2004Edited by: M. Kitsuregawa.     

Theory Extension in ACL2(r)

ACL2(r) is a modified version of the theorem prover ACL2 that adds support for the irrational numbers using nonstandard analysis. It has been used to prove basic theorems of analysis, as well as the correctness of the implementation of transcendental functions in hardware. This paper presents the logical foundations of ACL2(r). These foundations are also used to justify significant enhancements to ACL2(r).      

Irradiation effect on dielectric properties and electrical conductivity of Au/SiO2/n-Si (MOS) structures

The Au/SiO₂/n-Si (MOS) structures were exposed to beta-ray irradiation to a total dose of 30 kGy at room temperature. Irradiation effect on dielectric properties of MOS structures were investigated using capacitance−voltage (C−V) and conductance−voltage (G/ω−V) characteristics. The C−V and G/ω−V measurements carried out in the frequency range from 1 kHz to 10 MHz and at various radiation doses, while the dc voltage was swept from positive bias to negative bias for MOS structures. The dielectric constant (ε′), dielectric loss (ε″), loss factor (tan δ) and ac electrical conductivity (σ_ac) were calculated from the C−V and G/ω−V measurements and plotted as a function of frequency at various radiation doses. A decrease in the ε′ and ε″ were observed when the irradiation dose increased. The decrease in the ε′ and ε″ of irradiated MOS structures in magnitude is explained on the basis of Maxwell−Wagner interfacial polarization. Also, the σ_ac is found to decrease with increasing radiation dose. In addition, the values of the tan δ decrease with increasing radiation dose and give a peak. From the experimental results, it is confirmed that the peak of loss tangent is due to the interaction between majority carriers and interface states which induced by radiation.     

A systematic study on MOS type radiation sensors

Radiation sensors based on metal oxide semiconductor (MOS) structure are useful because of their superior sensitivity as well as excellent compatibility with the existing microelectronic technology. In this paper, a systematic study of MOS capacitors built on p- and n-type Si substrates with different SiO₂ thicknesses (10 nm, 50 nm, 100 nm and 240 nm) is presented. MOS device response to gamma radiation up to 256 Gray have been studied from the sensor application point of view. Variation of the radiation induced device response with oxide thickness, substrate type, applied bias and post annealing have been measured and discussed. Radiation induced charge in MOS devices is shown to be a strong function of the oxide thickness as expected. Application of a positive bias to the gate is found to enhance the device sensitivity for both n- and p-type devices. This is explained in terms of the involvement of the interface states in the sensing process. Devices have also been studied after repeated cycles of irradiation and annealing treatment under hydrogen atmosphere. Each cycle consists of gamma irradiation with 60 Gray dose and an anneal at 200 °C for 30 min. The charging-discharging mechanism during these cycles is discussed.     

热处理温度对Z型铁氧体反射损耗的影响

本文采用溶胶-凝胶工艺制备Z型铁氧体材料，并且通过不同的热处理温度对Z型铁氧体的成相结构、电磁参数、反射损耗的影响进行研究。结果表明，当热处理温度为1250℃—1275℃时，材料成相完全，磁导率增加，反射损耗增大。     

Crystallized TiO2 film growth on unheated substrates by pulse-powered magnetron sputtering

Crystallized TiO₂ films were successfully grown in situ without heating by bipolar-pulse sputtering method at high deposition rates (∼40 nm/min). The optical emission study of the sputtering plasma during growth revealed that the “pulse geometry” had a great influence on the electron/ion temperature of the plasma. It was revealed that the crystallization and the accompanying enhancement in the photocatalytic activity were not caused by the “temperature effect” but caused by the “plasma effect”.