教育卫星数字化宽带网接收系统的设计与调试

中国教育卫星宽带多媒体传输网的运行,标志着我国卫星教育节目传输进入了Ku频段和宽带、多媒体、数字化时代.介绍了教育卫星数字化宽带网接收系统,以理论和实践相结合的方法,阐述了系统的组成、工程参数的计算、器材的选择以及系统的安装和调试.     

第三代移动通信无线直放站链路预算

针对第三代移动通信制式之一的WCD-MA数字移动通信网中直放站的引入对系统产生噪声，引起基站或直放站接收机灵敏度下降的问题，通过调整直放站的上行增益GRep来控制噪声的增加量，以便达到所需的覆盖半径。     

Investigation of the electrical parameters of Ag/p-TlGaSeS/C Schottky contacts

p-type TlGaSeS single crystal was used to fabricate a Schottky device. Silver and carbon metals were used as the Ohmic and Schottky contacts, respectively. The device which displayed wide RF band at 13.200 and narrow band at 62.517 kHz with Q value of 1.4 and of 6.3 × 10⁴, respectively, is characterized by means of current (I)–voltage (V), capacitance (C)–voltage characteristics as well as capacitance–frequency (f) characteristics. The device series resistance, ideality factor and barrier height are determined from the I–V curve as 35.8 MΩ, 1.2 and 0.74 eV, respectively. The apparent acceptor density and the build in voltage of the device increased with increasing ac signal frequency. The high Q value, observed at 62.517 kHz, indicated a much lower rate of energy loss relative to the stored energy of the device. The energy loss (Q⁻¹) is much less than 0.001% of the stored value. The device was tested and found to remain at the same mode of resonance for several hours. It never switched or ceased unless it was tuned off.     

Revised and extended Utilities for the Ratip package

During the last years, the Ratip package has been found useful for calculating the excitation and decay properties of free atoms. Based on the (relativistic) multiconfiguration Dirac-Fock method, this program is used to obtain accurate predictions of atomic properties and to analyze many recent experiments. The daily work with this package made an extension of its Utilities [S. Fritzsche, Comput. Phys. Comm. 141 (2001) 163] desirable in order to facilitate the data handling and interpretation of complex spectra. For this purpose, we make available an enlarged version of the Utilities which mainly supports the comparison with experiment as well as large Auger computations. Altogether 13 additional tasks have been appended to the program together with a new menu structure to improve the interactive control of the program.

Program summary

Title of program: RATIPCatalogue identifier: ADPD_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADPD_v2_0Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions: noneReference in CPC to previous version: S. Fritzsche, Comput. Phys. Comm. 141 (2001) 163Catalogue identifier of previous version: ADPDAuthors of previous version: S. Fritzsche, Department of Physics, University of Kassel, Heinrich-Plett-Strasse 40, D-34132 Kassel, GermanyDoes the new version supersede the original program?: yesComputer for which the new version is designed and others on which it has been tested: IBM RS 6000, PC Pentium II-IVInstallations: University of Kassel (Germany), University of Oulu (Finland)Operating systems: IBM AIX, Linux, UnixProgram language used in the new version: ANSI standard Fortran 90/95Memory required to execute with typical data: 300 kBNo. of bits in a word: All real variables are parameterized by a selected kind parameter and, thus, can be adapted to any required precision if supported by the compiler. Currently, the kind parameter is set to double precision (two 32-bit words) as used also for other components of the Ratip package [S. Fritzsche, C.F. Fischer, C.Z. Dong, Comput. Phys. Comm. 124 (2000) 341; G. Gaigalas, S. Fritzsche, Comput. Phys. Comm. 134 (2001) 86; S. Fritzsche, Comput. Phys. Comm. 141 (2001) 163; S. Fritzsche, J. Elec. Spec. Rel. Phen. 114-116 (2001) 1155]No. of lines in distributed program, including test data, etc.:231 813No. of bytes in distributed program, including test data, etc.: 3 977 387Distribution format: tar.gzip fileNature of the physical problem: In order to describe atomic excitation and decay properties also quantitatively, large-scale computations are often needed. In the framework of the Ratip package, the Utilities support a variety of (small) tasks. For example, these tasks facilitate the file and data handling in large-scale applications or in the interpretation of complex spectra.Method of solution: The revised Utilities now support a total of 29 subtasks which are mainly concerned with the manipulation of output data as obtained from other components of the Ratip package. Each of these tasks are realized by one or several subprocedures which have access to the corresponding modules of the main components. While the main menu defines seven groups of subtasks for data manipulations and computations, a particular task is selected from one of these group menus. This allows to enlarge the program later if technical support for further tasks will become necessary. For each selected task, an interactive dialog about the required input and output data as well as a few additional information are printed during the execution of the program.Reasons for the new version: The requirement for enlarging the previous version of the Utilities [S. Fritzsche, Comput. Phys. Comm. 141 (2001) 163] arose from the recent application of the Ratip package for large-scale radiative and Auger computations. A number of new subtasks now refer to the handling of Auger amplitudes and their proper combination in order to facilitate the interpretation of complex spectra. A few further tasks, such as the direct access to the one-electron matrix elements for some given set of orbital functions, have been found useful also in the analysis of data.Summary of revisions: extraction and handling of atomic data within the framework of Ratip. With the revised version, we now ‘add’ another 13 tasks which refer to the manipulation of data files, the generation and interpretation of Auger spectra, the computation of various one- and two-electron matrix elements as well as the evaluation of momentum densities and grid parameters. Owing to the rather large number of subtasks, the main menu has been divided into seven groups from which the individual tasks can be selected very similarly as before.Typical running time: The program responds promptly for most of the tasks. The responding time for some tasks, such as the generation of a relativistic momentum density, strongly depends on the size of the corresponding data files and the number of grid points.Unusual features of the program: A total of 29 different tasks are supported by the program. Starting from the main menu, the user is guided interactively through the program by a dialog and a few additional explanations. For each task, a short summary about its function is displayed before the program prompts for all the required input data.     

DVB数字视频广播中Eb/N0与C/N的关系

在DVB数字视频广播系统中，能够用Eb／N0或C／N来表征系统基本性能，介绍Eb/N0和C／N的概念，并描述Eb／N0与C/N的代数关系。     

A program for accurate solutions of two-electron atoms

We present a comprehensible computer program capable of treating non-relativistic ground and excited states for a two-electron atom having infinite nuclear mass. An iterative approach based on the implicitly restarted Arnoldi method (IRAM) is employed. The Hamiltonian matrix is never explicitly computed. Instead the action of the Hamiltonian operator on discrete pair functions is implemented. The finite difference method is applied and subsequent extrapolations gives the continuous grid result. The program is written in C and is highly optimized. All computations are made in double precision. Despite this relatively low degree of floating point precision (48 digits are not uncommon), the accuracy in the results can reach about 10 significant figures. Both serial and parallel versions are provided. The parallel program is particularly suitable for shared memory machines such as the Sun Starcat series. The serial version is simple to compile and should run on any platform.

Program summary

Title of program: corr2elCatalogue identifier: ADUXProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUXProgram obtainable from:CPC Program Library, Queen's University of Belfast, N. IrelandDistribution format: tar.gzComputer for which the program is designed and others on which it has been tested:Computers: Sun Fire 15K StarCat, Sun Ultra SPARC III, PCOperating systems or monitors under which the program has been tested: Sun Solaris 9, LinuxProgramming language used: ANSI CMemory required to execute with typical data: 3 Mwords or moreNo. bits in a word: 32No. processors used: arbitraryHas the code been vectorized or parallelized: parallelizedNumber of lines in distributed program, including test data, etc.:5885Number of bytes in distributed program, including test data, etc.: 26 199Nature of physical problem: The Schrödinger equation for two-electron atoms is solved using finite differences.Method of solution: An iterative eigenvalue-solver that requires only the action of the Hamiltonian on a trial function is applied. The two-electron wave function is expanded in a sum of partial waves. The finite difference method is then applied to approximate the derivatives of the pair functions. The total action of the Hamiltonian on the partial waves, including correlation effects, is computed using highly optimized routines.Restriction on the complexity of the problem: The Hamiltonian employed here does not take relativistic or finite nuclear mass effects into account. The amount of computing time may become unreasonable for excited states far above the ground state. The use of double precision puts a limit on the accuracy obtainable.Typical running time: This ranges from half a minute (to obtain 10 significant figures for the s-limit of the Helium ground state) to perhaps a day for advanced examples depending on the level of parallelization.Unusual features of the program: The implicitly restarted Arnoldi method used to obtain the eigenvalues is implemented by using the ARPACK/PARPACK program library [http://www.netlib.org/arpack]. This package also depends on the standard numerical libraries BLAS and LAPACK [http://www.netlib.org/lapack]. Good performance is obtained by using Sun's optimized performance libraries [http://www.sun.com]. By using a 64-bit environment (Ultra SPARC III and Solaris 9), memory limitations are non-problematic. Shared memory is used in the parallel version. Fast communication between the nodes is made over shared memory using Sun's implementation of MPI.     

A program of generation and selection of configurations for the configuration interaction method in atomic calculations SELECTCONF

This program written in FORTRAN is aimed at generation and selection of the admixed configurations which are used in the theoretical calculations of atomic states by the configuration interaction (CI) method. The admixed configurations are generated and selected using the file of radial orbitals written down in the form adopted in the code [C. Froese Fischer, Comput. Phys. Comm. 43 (1987) 355] and other analogous codes. Selection of configurations is performed on the ground of evaluations in the second order of the perturbation theory [P. Bogdanovich, R. Karpuškien?, Comput. Phys. Comm. 134 (2001) 321; R. Karpuškien?, R. Karazija, P. Bogdanovich, Phys. Scripta 64 (2001) 333]. Output of selected configurations is arranged in a format suitable for the codes generating the configuration states [C. Froese Fischer, B. Liu, Comput. Phys. Comm. 64 (1991) 406; P. Bogdanovich, A. Momkauskait?, Comput. Phys. Comm. 157 (2004) 217].

Program summary

Title of program:SELECTCONFCatalogue identifier:ADWDProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWDProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions:NoneComputers:Any computer with a FORTRAN 77 compilerOperating systems under which the program has been tested:LinuxProgramming language used:FORTRAN 77Memory required to execute with typical data:4 MBNo. of lines in distributed program, including test data, etc.:7459No. of bytes in distributed program, including test data, etc.:108 420Distribution format:gzip fileNature of the physical problem:Due to the restricted possibilities of the computers and codes, which are employed, the practice of CI requires one to select and superpose those configurations the usage of which happens to be the most effective. This program is designed for the selection of such admixed configurations.Method of solution:All admixed configurations possible in the specified basis set of radial orbitals (RO) are constructed using the one-electron and two-electron virtual excitations. Then the averaged evaluation of their influence on the energy or wave function of the adjusted configuration is performed in the second order of perturbation theory. The results of this evaluation are used for the selection of admixed configurations.Restrictions onto the complexity of the problem:In the present version of the program the number of passive shells is restricted by MIUZ=20; the number of active shells by MIAT=10; the number of generated admixed configurations, by MECO=10000; the number of RO used, by MOR=MRO=99. All these limitations are not hard-coded and can be changed by substituting the values of the corresponding parameters.Unusual features of the program:The possibility of carrying out the averaged evaluation of the influence of admixed configurations in the second order of perturbation theory and to perform their selection on this ground.Typical running time:Several seconds. This time depends on the size of the problem: the computation time depends approximately linearly on the number of possible admixed configurations, which increases rapidly with a growing number of active shells and an extending RO basis set.     

小口径天线接收中星6B卫星电视信号的功率储备评估

2007年转星后,国内大量个体接收用户采用小口径天线接收中星6B卫星的状况,本文通过理论计算和实地测量,对小口径天线接收系统的功率储备进行了评估和分析,并给出了最终的结论。     

Study of the temperature evolution of defect agglomerates in neutron irradiated molybdenum single crystals

Small angle neutron scattering as a function of temperature, differential thermal analysis, electrical resistivity and transmission electron microscopy studies have been performed in low rate neutron irradiated single crystalline molybdenum, at room temperature, for checking the evolution of the defects agglomerates in the temperature interval between room temperature and 1200 K. The onset of vacancies mobility was found to happen in temperatures within the stage III of recovery. At around 550 K, the agglomerates of vacancies achieve the largest size, as determined from the Guinier approximation for spherical particles. In addition, the decrease of the vacancy concentration together with the dissolution of the agglomerates at temperatures higher than around 920 K was observed, which produce the release of internal stresses in the structure.     

DVB-C系统在高斯信道下的理论性能

本文对DVB—C系统在高斯信道下的理论性能进行了分析，并进行了蒙特卡罗仿真，获得了64QAM的BER～Eb/N。、Eb/N。～MER和BER～MER性能曲线。此外还对MER、C／N、S／N、Eb/N。的关系进行了分析，结合仿真结果和测量结果重点讨论了MER在数字有线电视测量和实践中的重要作用。