河北省中央节目地面数字电视覆盖网优化研究

本文所述工作是中央广播电视节目无线数字化覆盖工程的一部分。本文概括介绍了河北省频率规划方案,逐一确定了网络优化工作所需的技术参数,重点分析了网络优化工作的原理和方法。通过区域单频网和多频网实例,解决了存在的干扰问题,提出了河北省中央节目地面数字电视覆盖网组网的优化参数和方案,为其他省份开展类似工作提供了技术参考。     

掺Cr,Ni对S在Fe(100)面吸附的第一性原理研究

基于密度泛函理论(DFT)的第一性原理方法,在广义梯度近似下计算了Fe中掺Cr或Ni时S原子在Fe(100)面吸附的结构和电子性质,并计算了其分子轨道和吸附能。结果表明:S原子均是吸附在H位最稳定;纯铁时S在Fe(100)面H位的吸附能为-7.70 eV,掺Ni时S原子在H位的吸附能为-7.35 eV,吸附能的相对变化为4.5%;掺Cr时S原子在H位的吸附能为-5.79 eV,吸附能相对纯铁时变化为24.8%,表明掺Cr对S原子在Fe表面的吸附抑制作用更大。对比分析了每种吸附情况下的分波态密度,结果发现掺Cr时具有较高的局域电子云重叠,从而产生的排斥作用抑制了S原子的吸附。     

Optimum Design for RF Windows in Millimeter Wave High Power Tubes

The pill-box and block RF windows for millimeter wave (MMW) tubes are presented. The pill-box window is suitable for broadband MMW tubes. And the block window can be used for high power tubes in short MMW. The equivalent circuits for two windows are given. To reach better match characteristics in wider operating bandwidth, the optimum design methods for pill-box and block window in MMW tubes are described in this paper. The testing results show that the theoretic computation is fast and useful accuracy. The design methods possess references value to designer for MMW tubes.     

Volterra series representation of a forward-biased p-i-n diode

A nonlinear model is proposed for a forward-biased p-in diode controlled by an ac signal consisting of a group of sinusoidal signals. The model is applicable to these phases of diode operation where linearized basic physical equations are valid. Current-voltage relations have been obtained for junctions and the "i" region in the form of a Taylor series with frequency-dependent coefficients. The new model is valid for signal levels considerably exceeding those admissible for the known linear model [3], [4]. A new form of signal limiting condition, suitable for measurement verification and calculations, has been obtained. The Volterra series for the equations representing the diode has been found which correspond to the Taylor series obtained. The convergency condition for this series is identical to that for thel Taylor series. The conformability of measurement and calculation results fully testifies to the usefulness of the proposed model for nonlinear distortion analysis.     

Image Processing of Biological Liquids Films for Medical Diagnostics

In this paper, the development of smart medical autonomous technology is considered. An example of a smart medical autonomous distributed system for diagnostics is also discussed. To develop this system for medical image analysis we review several processing methods. The use of the cuneiform dehydration method for medical diagnosis is considered. The experimental results obtained for blood serum dehydrated films are presented. The author proposes an algorithm for the primary identification of structures formed in the films and their use for automated detection of various structures for diagnostic purposes. The paper describes the first stage of image processing, i.e. the selection of filtering types for the correct identification of structural features and characteristics of the images. The results of filtering and some computational results of various types of structures in the films are presented.     

Address decoding for randomly scattered memory segments of equalsize

The authors explain two methods for obtaining the address decoding expressions for memory segments of equal size. The first method is based on Karnaugh map and is useful for short segment addresses. The second method is a tabular approach, useful for longer segment addresses. Examples are provided for both methods     

Supercomputers-perspectives on visualization

The role of visualization and its capabilities are discussed. The loss of information incurred in translating a three-dimensional scene into a two-dimensional image plane and ways of compensating for it are considered. The need for interactive capability is stressed. The dichotomy between the use of visualization for analysis and for communication is traced to the way the technology evolved. That is, historically, computer graphics has been used in two separate and quite different industries: for science and engineering, and for entertainment. The emergence of cross-fertilization between the two is examined. Future trends and challenges are discussed     

Spatially Adaptive Estimation via Fitted Local Likelihood Techniques

This paper offers a new technique for spatially adaptive estimation. The local likelihood is exploited for nonparametric modeling of observations and estimated signals. The approach is based on the assumption of a local homogeneity of the signal: for every point there exists a neighborhood in which the signal can be well approximated by a constant. The fitted local likelihood statistics are used for selection of an adaptive size and shape of this neighborhood. The algorithm is developed for a quite general class of observations subject to the exponential distribution. The estimated signal can be uni- and multivariable. We demonstrate a good performance of the new algorithm for image denoising and compare the new method versus the intersection of confidence interval (ICI) technique that also exploits a selection of an adaptive neighborhood for estimation.     

基于泰勒分布线阵特殊旁瓣技术的研究

提出了基于泰勒加权分布线阵特殊旁瓣要求的设计方法,其波束图是由给定的旁瓣级要求来设计的泰勒分布波束图,在实际需要的特殊旁瓣要求上,设计满足了要求的最窄波束宽度波束图。给出了相应的参数设计,并证明该设计能在要求的最大旁瓣级上获得最大阵增益。借助计算机对线阵进行波束图设计。结果表明,使用该方法设计的波束图能满足特殊旁瓣要求和最大阵增益。     

Waveguide discrete modes in slab and cylindrical FIR laser

The characteristic equation is solved for oversized slab and cylindrical hollow waveguides. The outter medium is a dielectric or a metal for cylindrical waveguides, and a dielectric for slab waveguides. The results are applied to consider the resonance conditions for a FIR laser cavity.     

The infrared physical layer of the IEEE 802.11 standard forwireless local area networks

The new IEEE 802.11 standard for wireless local area networks defines a specification for an infrared physical layer. This article gives an overview of infrared technology and describes the IEEE 802.11 specification in detail, presenting a historical perspective of its development. The infrared physical layer was designed for diffuse systems supporting two data rates (1 and 2 Mb/s) and includes provisions for a smooth migration to higher data rates. The specification is suitable for low-cost transceivers but allows interoperability with higher-performance systems. The main application envisaged for IEEE 802.11 infrared wireless local area networks is ad hoc networks     

Phased Mission Analysis: A Review of New Developments and An Application

Both exact and approximate methods for obtaining the unreliability of a nonrepairable system undergoing a phased mission are presented. The techniques are applied to an emergency core cooling system for a boiling water reactor. The estimates for the example agree well with the exact solution. The accuracy and ease of implementation are compared for both methods. The approximation techniques for unavailability estimates for phased missions contained in this paper are useful for industrial applications. The techniques are implementable and existing computer programs such as MOCUS, PREP, and KITT can be used for the analysis although such use is not efficient at this time. These programs are currently being modified, for efficient use in phased mission problems, at the Idaho National Engineering Laboratory. MOCUS, PREP, and KITT are obtainable from the Argonne Code Center; 9700 South Cass Avenue; Argonne, IL 60439 USA.     

Reduction of motion artifacts using a two-frequency impedanceplethysmograph and adaptive filtering

The authors measured transthoracic impedance in nine presumed healthy adult subjects with a two-frequency plethysmograph at 57 kHz and 185 kHz. The measurement protocol included periods of normal breathing without motion and periods of motion without breathing. The authors analyzed the cross-correlation and the ratio between the signals at both frequencies for all the different maneuvers. The correlation coefficient was between 0.97 and 1 for breathing, the minimal cross-correlation (0.81) was for simulated obstructive apnea. The authors found that the amplitude ratio between the two-frequency signals was different for normal breathing and for motion. Based on these results, the authors designed and tested an adaptive filter to increase the signal-to-artifact ratio (SAR). The increase in SAR (mean±standard deviation) compared with the signal at 57 kHz was: 183%±117% for arm movement, 133%±93% for leg movement, and 34%±62% for simulated obstructive apnea     

铝电解电容器技术的新进展

详细讨论了电子技术的发展对铝电解电容器的性能要求,提出了其技术对策,分析了存在的技术瓶颈,找出了它的技术出路,探讨了它的技术难点,给出了当前我国铝电解电容器行业的技术现状,指出了未来发展方向。     

Moving window detection for discrete data (Corresp.)

The moving window detection procedure for discrete data is studied. Bounds for the probabilities and expected values of the waiting time for a detection are derived. The bounds are evaluated for independent identically distributed zero-one Bernoulli trials, binomial, and Poisson random variables, and also for the two-state stationary Markov chain. The results are applicable to the theory of radar detection, time sharing systems, and quality control.     

Temperature control for food in pots on cooking hobs

A control system for the temperature of food in a cooking pot is introduced. The cooking pot is heated on a consumer cooking hob. The temperature of the pot side is used as input for the controller. It is measured by an infrared detector. The infrared detector is a thermopile. The sensor signal is evaluated by a rule-based control algorithm. The system is simple, reliable, and very user friendly. An exact temperature settlement in a consumer hob is available for the first time. The system is used for automatic cooking     

A recursive T-matrix approach for the solution of electromagneticscattering by many spheres

The generalized recursive aggregate T-matrix algorithm (RATMA) is used to solve for the multiple scattering solution for over 6000 spheres. The solution is valid for all angles of incidence. An efficient method is used to calculate the coefficients for the vector addition theorem. This, together with the use of the generalized RATMA, makes calculation possible for many-particle scattering. The theory can be used for Monte Carlo simulation in remote sensing and geophysics applications     

Self-capacitance of inductors

A new method for predicting the stray capacitance of inductors is presented. The method is based on an analytical approach and the physical structure of inductors. The inductor winding is partitioned into basic cells-many of which are identical. An expression for the equivalent capacitance of the basic cell is derived. Using this expression, the stray capacitance is found for both single- and multiple-layer coils, including the presence of the core. The method was tested with experimental measurements. The accuracy of the results is good. The derived expressions are useful for designing inductors and can be used for simulation purposes     

高硬度薄膜溅射工艺稳定性分析

本文简要介绍了当前高硬度薄膜制备的常用工艺方法，着重分析了反应溅射的工艺条件，对反应溅射系统中的粒子输运进行了详细的分析，讨论了该工艺条件下薄膜制备的稳定性条件。     

An operational amplifier model for evaluating test strategies at behavioural level

This paper proposes a new operational amplifier model for evaluating test strategies at behavioural level. Major modifications on a previously reported model for improving its performance and for allowing reliable fault simulations are presented here. The new model presents a set of very appealing characteristics for behavioural-level fault injection and simulation.The matching between the behavioural-level model and a transistor-level one is evaluated for validating the model. We suggest the use of the model early in the design process, when the schematic of the circuit is not available for the test engineer and only the specifications are given. The model is also useful for evaluating different test alternatives for commercial operational amplifiers or standard cells designed by others vendors. The paper addresses two application examples and shows the usefulness of the model for evaluating test strategies when only the specifications of the circuit are available.