ABB变频器在双馈发电机试验台上的应用

本文介绍了风力发电系统目前存在的技术方案，重点介绍了ABB用于双馈式风力发电系统的变频产品ACS800—67的特性，并对由其构建的发电机测试平台的案例进行了实验分析。     

Detrended Fluctuation Analysis of the Human EEG during Listening to Emotional Music

A nonlinear method named detrended fluctuation analysis （DFA） was utilized to investigate the scaling behavior of the human electroencephalogram （EEG） in three emotional music conditions （fear, happiness, sadness） and a rest condition （eyes-closed）. The results showed that the EEG exhibited scaling behavior in two regions with two scaling exponents β1 and β2 which represented the complexity of higher and lower frequency activity besides α band respectively. As the emotional intensity decreased the value of β1 increased and the value of β2 decreased. The change of β1 was weakly correlated with the ＇approach-withdrawal＇ model of emotion and both of fear and sad music made certain differences compared with the eyes-closed rest condition. The study shows that music is a powerful elicitor of emotion and that using nonlinear method can potentially contribute to the investigation of emotion.     

Photoluminescence characteristics of ZnTiO3: Bi nanocrystals

The photoluminescence properties of the Bi³⁺ in sol-gel derived ZnTiO₃ nanocrystals have been investigated. An ultra-violet emission at 360 nm and a visible emission band at 506 nm have been observed, originating from two kinds of emission centers. The former is ascribed to the ³P₁-¹S₀ transition of Bi³⁺ and the latter to the recombination of the electrons with the photo-generated holes trapped in the zinc vacancies. In all cases the latter contribution is predominant.     

NOESY技术在地胆草倍半萜内酯化合物结构鉴定中的应用（I）

明确从地胆草中分离得到的两对牦牛儿内酯型的立体异构体即地胆草种内酯（scabertopin）、异地胆草种内酯（isoscabertopin）、异去氧地胆草内酯（isodeoxyelephantopin）和去氧地胆草内酯（deoxyelephantopin）的C-2相对构型；方法 NOESY技术，并结合这4个化合物的¹H NMR，¹³C NMR，HMQC谱；结果 两对立体异构体的NOESY谱有明显差异；结论 通过分析NOESY谱，找寻H-1相关信息，若发现H-1与H-8，H-9β和14-CH₃有NOE相关，可以判断化合物的C-2为α构型，若H-1与H-5，H-7，H-3α及H-9α之间有NOE相关，则化合物的C-2为β构型.     

曲轴激光喷丸强化试验研究

采用实验的方法,研究了激光冲击强化对175A型柴油机曲轴疲劳寿命的影响,取得了激光冲击强化试验条件下曲轴过渡圆角处残余应力场的数据。并将激光冲击强化工艺效果和曲轴滚压强化效果做了对比性分析,结果表明：虽然激光冲击强化效果不如曲轴滚压强化,但考虑到激光工艺参数精确可控、加工质量好、成本低以及可避免滚压强化所造成的表面疲劳、撕痕等,激光冲击强化工艺可望代替滚压强化成为新型的曲轴强化手段。通过此类激光冲击强化强化实验可优化激光冲击的相关参数,使曲轴过渡圆角产生有利的残余应力场。     

Measurement of gain spectrum for Fabry-Perot semiconductor lasers by the Fourier transform method with a deconvolution process

To improve the accuracy of measured gain spectra, which is usually limited by the resolution of the optical spectrum analyzer (OSA), a deconvolution process based on the measured spectrum of a narrow linewidth semiconductor laser is applied in the Fourier transform method. The numerical simulation shows that practical gain spectra can be resumed by the Fourier transform method with the deconvolution process. Taking the OSA resolution to be 0.06, 0.1, and 0.2 nm, the gain-reflectivity product spectra with the difference of about 2% are obtained for a 1550-nm semiconductor laser with the cavity length of 720 /spl mu/m. The spectra obtained by the Fourier transform method without the deconvolution process and the Hakki-Paoli method are presented and compared. The simulation also shows that the Fourier transform method has less sensitivity to noise than the Hakki-Paoli method.     

High‐Performance,Monolithic Polyaniline Electrochemical Actuators

New polyaniline (PANI) asymmetric membranes were fabricated using a phase‐inversion technique with hexane as the coagulation bath. These membranes exhibit a dense structure with macrovoids distributed asymmetrically throughout the cross‐section. A stress–strain study demonstrated that the Young's modulus (1.421 GPa) and strain at break (7.6 %) of the new PANI asymmetric membranes prepared from hexane are approximately 12 and 4 times higher, respectively, than the values reported previously for the PANI integrally skinned asymmetric membranes (ISAMs) (123 MPa Young's modulus and 1.8 % strain at break). Furthermore, monolithic electrochemical actuators based on a single PANI asymmetric membrane were constructed, and a bending movement of up to 20 Hz was experimentally recorded in a hydrochloric acid aqueous solution. A lifetime of over 329 500 cycles was determined for these actuators at a ± 2° angular displacement (5 Hz). The lifetime is limited by a bending fatigue that creates a transversal crack on the PANI membrane at the air–water interface. Control over the actuator movement is also manifested by the linear dependences of the bending angle on the charge and of the angular velocity on the current. These relationships are independent of both the kind of applied electric signal and the frequency used.     

Ionic conductivity of epitactic MBE-grown BaF2 films

We studied parallel conductivities of pure BaF₂ films with thicknesses ranging from 35 to 300 nm, epitaxially grown on Al₂O₃(0 1 2) substrates by molecular beam epitaxy technique. The overall conductivities of the films are found to increase with decreasing thickness. The detailed investigation of the overall conductance as a function of the thickness permits the deconvolution of bulk and boundary effects, the latter being attributed to distinct space charge effects in the interface between BaF₂ film and Al₂O₃ substrate. The (extrinsic) Debye length (λ) is estimated to be about 8 nm at T=593 K, which corresponds to an impurity content of 10¹⁸/cm³ (singly ionized dopant assumed). This is consistent with the fact that we observed a constant boundary contribution for all investigated films (film thickness >4λ). It is also consistent with the Debye length observed in a previous report on CaF₂/BaF₂ heterolayers fabricated by the same technique, in which the low temperature enhancement was also attributed to space charges in BaF₂ [Nature 408 (2000) 946]. Only at low temperatures (below 370 °C), the conductance seems to be influenced by strain effect.     

关于《一类奇异边值问题的正解》的注记

文[4]通过构造反例断言文[1]中定理的必要性证明有误,本文首先指出文[4] 的这个断言不正确,然后对文[4]中定理2.1作了本质性的改进.     

靶场测量雷达新一代引导接收机

介绍了靶场测量雷达新一代引导接收机。它是一种模拟／数字混合型锁相接收机，可对ＵＳＢ（ＵｎｉｆｙＳ－Ｂａｎｄ）信号进行谱线识别和谱线跟踪，其捕捉范围和跟踪范围可达±１８０ｋＨｚ。它能提供目标角误差信号、目标强度信息和目标速度信息。