用解析表达式计算螺旋电感的S参数

推导出了计算方形螺旋电感模型各电路元件值的解析表达式，其中包括了频率和基片厚度的影响。计算３个电感的参数，所得结果与测试值吻合较好。     

基于PSASP程序的励磁系统PID控制的仿真与验证

励磁系统的PID参数对发电机组和电网稳定的可靠性和动态品质具有重要的作用。检验励磁系统PID参数准确性的方法主要是进行发电机空载阶跃响应试验。本文采用中国电力科学研究院研制的电力系统综合仿真程序PSASP对沧东电厂4号机励磁系统进行了5%机端电压阶跃仿真试验,然后根据仿真结果进行了现场试验,结果表明仿真结果对现场试验具有重要的指导意义,不仅节省了现场调试的时间,而且进一步提高了现场试验的安全性。     

Bringing the fiber to the home

The issues involved in replacing copper telephone lines by fiber all the way to the subscriber's home are examined. The advantages of deploying single-mode fiber in the trunk and local-loop feeder networks are enumerated. The biggest problem namely, how to power the electronics in the absence of copper wire, is discussed. The need to allow a graceful upgrade to capture future opportunities for broadband revenue is emphasized, and potential broadband services are described. Predictions are made regarding the ISDN network of the future     

Multiregime character of the nonlinear precession of the second-order magnetization under the conditions for the orientational transition

The forced nonlinear precession of the magnetization vector in the normally magnetized magnetic plate is considered under the conditions for the orientational transition. The time dependences and precession patterns of the oscillations of magnetization are presented. Five regimes of precession are revealed: small-amplitude circular precession, precession of the equilibrium position without encircling of center, undamped precession of equilibrium position with encircling of center, damped precession of equilibrium position with encircling of center, and full-scale circular precession. The transitions between the regimes are studied using the 3D model of potential. The domains of the regimes of precession are determined on the plane decay parameter-ac field amplitude. It is demonstrated that a variation in the amplitude of the ac field leads to the stepwise dynamic orientational transition from the fourth regime to the fifth regime. The recommendations for the practical applications are worked out using the results.     

Assessing the Core Resources in the Environmental Management System From the Resource Perspective and the Contingency Perspective

The purpose of this paper is twofold. The first objective is to examine the core resources that make environmental management system (EMS) a potential basis of sustainable competitive advantage from the resource-based view of the firm. The second objective is to investigate the set of core resources from the contingency perspective. Particularly, experience in implementing other manufacturing systems and the stage of EMS implementation were tested as the contingency factors. The proposed model and its related hypotheses were tested using structural equation modeling on a large-scale database consisting of 1453 respondents. The results showed that it is the tacit resources within an EMS, in the form of top management team's strategic perception, cross-functional cooperation, and environmentally responsible suppliers, which help explain firmspsila operational performance. The findings provided the general principles in investment decisions of EMS. However, the results also demonstrated that the pattern of the core resources varies across firms with different experience in other manufacturing systems and at different stages of EMS implementation. As a result, there is no standard bundle of critical resources for each firm. Rather, firms need to tailor their resource investment decisions in light of these factors beyond the general principles.     

Unlocking the power of the Grid

The Grid, it is widely agreed, is the next big thing in computing, but a consensus on what exactly it is can be harder to come by. Grid computing implies the idea of accessing computational resources over a network, the Internet, untroubled by low-level concerns about where these resources might be located. Almost inevitably, the US is in the lead, with NASA's Information Power Grid (IPG) providing the world's most credible example of a functioning Grid. The objective of the IPG is to facilitate the interconnection of computing systems across a number of NASA sites, allowing, for example, the multi-site simulation of a whole space shuttle design. The paper discusses the e-Science Programme. The UK e-Science Grid represents a technical challenge, operating across nine separate centres, each with their own IT policies. Each of the centres on the e-Science Grid provides a local knowledge-base of Grid expertise, implementing currently available public-domain Grid middleware, including the Globus Toolkit, and developing a portfolio of industrial projects     

ECM的相位受振膜材料影响的讨论

着重讨论了驻极体电容传声器(ECM)的相位受振膜材料影响的问题,即振膜的基材在生产中,受生产过程影响而对振膜产生影响的分析,以及各种因素形成的应力对驻极体电容传声器(ECM)相位影响的分析.     

Effects of the nature of the starting population on the propertiesof Rugate filters designed with the genetic algorithm

The genetic algorithm optimization technique for optical filter design is applied to two starting populations, an inverse Fourier transform population and a random population. The refractive index profiles after convergence, and the transmittance of the filter outside the region of support, are markedly different in the two cases. The Fourier filter has lower sidelobes and fails gracefully outside the region of support whereas the random filter fails catastrophically in this wavelength region. The ripple in the passband is higher for the random filter. Furthermore, the average value of refractive index profile and the excursion in refractive index are much larger for the filter generated with the random starting population. However, most of the drawbacks of the random starting population are eliminated by chromosome manipulation in the spatial frequency domain. The fitter properties after this intervention approximate those of the Fourier filter     

Relations Between the Winding Errors of the Double Pancakes and the Spherical Harmonics Expansion of the Field

A 500-MHz whole-body magnetic-resonance-imaging magnet has been under study for the Iseult/Inumac project since 2006. The central field of this magnet must be 11.7 T in a warm bore of 900 mm. The required field homogeneity is 0.5 ppm peak to peak in a sphere of diameter 22 cm. An innovative winding method using double pancakes (DPs) was devised to handle these outstanding specifications. The choice of the used method will be explained. Among the different sources that can generate field errors, we shall focus on the winding errors while manufacturing. The accuracy on the magnetic field must be less than a few parts per million, which implies precisely evaluating the effects of these errors on the field quality. Therefore, different methods were developed in that aim. The principle of each of these methods will be given. A code that links the winding data to the errors on the spherical harmonics expansion was then written. To check the availability of the results, the code was applied to several cases whose exact solution is known. Finally, the code was applied to wound DPs for the prototype H0 of Iseult. A first estimation of the mechanical tolerances on the winding will be done.      

无源雷达协同定位精度仿真研究

无源雷达定位精度直接影响雷达的作战使命,本文分析了对典型运动目标双站协同测距理论定位精度,具体给出了提高双站定位精度优化算法的计算机仿真结果,并在计算机仿真结果基础上讨论这种方法的应用范围和需要注意的问题。     

Generalization of the Lee Method for the Analysis of the Signal Variability

The Lee method, which was recommended by the International Telecommunications Union (ITU) and the European Conference of Postal and Telecommunications Administrations (CEPT) to obtain the local mean values of the received signal along a route, was developed for a Rayleigh distribution in the ultrahigh-frequency (UHF) band. This paper describes the generalization of this method to any propagation channel and frequency band and describes the methodology to obtain the parameters involved. The Generalized Lee Method is based on field data samples, which allows estimating the mean values without the requirement of a priori knowing the distribution function that better fits the propagation channel. The accuracy in obtaining the averaging interval is also improved. The Generalized Lee Method is solved for ground-wave propagation at the medium-wave (MW) band, taking data from field trials of a Digital Radio Mondiale (DRM) transmission. The results show that the values considerably differ from those obtained for a Rayleigh channel and prove that the method allows the adequate differentiation of long-term and shortterm signals. The Generalized Lee Method completes the results obtained by Lee and Parsons and makes better characterization of the spatial variability possible.      

BP神经网络对固井信号分类能力的研究

本文研究了BP神经网络对固井信号的分类能力．首先应用理论框模型分析了不同层状介质结构的回波，并系统深入地研究了层状介质物理参数的变化对BP神经网络分类的影响。理论研究结果表明，当各层介质参数在一定范围内变化时，不影响网络的正确分类，即BP神经网络对固井信号分类具有很强的Robust性。本文也给出了对实际困井信号的分类结果，其正确识别率在叨％以上。该研究结果反映出BP神经网络具有很强的信号分类能力，对将其用于固并信号分类的工程实际有重要价值。     

Automation of the Measurement Process of the Parameters of the Sensitive Elements of the Gas Flow Rate Sensors

Russian Microelectronics - The study of the characteristics and errors of sensors is as difficult as designing and manufacturing them. The operation of sensors needs to be accurately studied in...     

Application of the wavelet transform to the problem of the detection and determination of the Lorentzian positions of the 2D band in the Raman spectrum of bilayer graphene

Semiconductors - The possibility of quantifying the number of graphene layers using the integral wavelet transform is shown. The integral wavelet transform is applied to process the 2D band of the...     

用强场中的高次谐波标定单色仪

利用实验中测得的高次谐波,对实验中使用的美国Acton公司生产的VSN－515型0．5m真空紫外单色仪进行标定,标定结果表明,单色仪的数字式波长显示器直接同以0．1nm为单位的波长数值与实际的射线辐射波长值符合的奶好,但是,每次对射线辐射测量时,光栅必须从波长短向波长长的方向进行扫描,否则会出现由于单色仪驱动光栅转传动的步进电机向不同方向转向引起的误差。     

On the asymptotics of the busy period tail under the critical load

The behavior of the tail of the busy period distribution in the M/G/1/∞ conservative queueing system under the critical load ρ = 1 is studied. The distribution function of the service time belongs to the class of regularly varying functions. Two cases are investigated: the finite and infinite second momentsof the service time distribution. The first of these cases is considered in [7], where the service time distribution is not assumed to be a regularly varying function.     

星敏感器的星点定位方法研究

介绍了星敏感器的基本工作原理,分析了星图的特点．并结合星图的特点对星图阈值的确定和内插细分算法进行了研究,从理论和实践两个方面对星点定位算法进行了分析,最后确定了适合星图使用的星点定位方法。并用星敏感器对该定位方法进行了试验检验,取得了较为满意的结果。     

On the theory of the electrocardiogram

The biophysical basis for understanding the electrocardiogram is set forth. Bioelectric sources arise from electrical activity in the heart at the cellular level. The relation of these sources, which can be formally represented as impressed currents, to potentials involves solution of the volume conductor problem. This solution is based on Green's theorem. Sources are related to the transmembrane action potential through a bidomain model of heart muscle. Microscopic and macroscopic aspects of the bidomain model are developed. Various transformations of the source are considered, including multipoles, multiple dipoles, and replacement of the volume distribution with distributions on the heart surface. Time integrals of the waveform are related to excitation time and action potential duration. The theoretical results form the basis of a computer model of the electrocardiogram that relates skin potentials to the spatial and temporal distribution of action potentials in the heart     

提高金属化电容器喷金质量探讨

金属化电容器端面喷金质量对电容器主要电性能指标——tg,起着决定性的影响。分析了影响金属化电容器端面喷金质量的因素,介绍了提高金属化电容器端面喷金质量的方法及如何检查金属化电容器端面喷金质量。     

PTN流量监控方案研究

PTN流量监控能够确保电信运营商全面掌握PTN网络流量的使用状况,合理统计资源使用效率,有效开展资源预警扩容和流量均衡优化工作,防止出现网络拥塞,切实保障各类业务的传送质量。本文在PTN流量监控方面做了一些简单的探讨和研究。