Design parameters and measured performance of the IRAM 30-mMillimeter Radio Telescope

The “Millimeter Radio Telescope” (MRT) is operated by the Institute for Radio Astronomy in the millimeter range (IRAM) and is located at 2850-m altitude in the Sierra Nevada, near Granada, Spain. It is a reflector antenna of 30-m diameter with a surface accuracy of 0.08 mm and a pointing accuracy of better than 2 arcsec. The telescope is equipped with sensitive receivers for the atmospheric windows between 0.8- and 7-mm wavelength. The authors describe the optics layout of the receiver and calibration system, which allows simultaneous observations at a number of frequencies. The special design aspects of the antenna, in particular the control of thermal deformations and the achievement of a high reflector and pointing accuracy are described. The authors compare the design computations with the characteristics of the telescope, derived from several years of operation and optimization. The success of the design is demonstrated by observational experience. The authors conclude the paper with a short review of some of the astronomical results obtained with the telescope     

系统级封装(SiP)组装技术与锡膏特性(续)

4 结果和讨论 4.1 焊盘间的桥接 结果比较表明,使用不同的治具配置有明显的区别.使用平台治具作为板支撑的激光切割钢网在80 μm间隙的情况下未发现桥接.使用真空支撑时,激光切割钢网在50 μm间隙的情况下也未发现桥接.这说明使用真空支撑在印刷时的钢网和电路板间间隙更小,支撑性能更好.图5显示了其在125 μm×15...     

Effect of Melt Conditioning on Removal of Fe from Secondary Al-Si Alloys Containing Mg,Mn, and Cr

Metallurgical and Materials Transactions A - Primary intermetallic sludge formation in hypoeutectic secondary Al7.1Si(1.5-xM)FexMM alloys was investigated in view of potential Fe removal by...     

Die Fließgrenze bei behinderter Formänderung

Ohne Zusammenfassung Mitteilung aus der Staatlichen Materialprüfungsanstalt an der Techn. Hochschule Darmstadt Der Notgemeinschaft der Deutschen Wissenschaft sei an dieser Stelle für die Unterstützung der Versuche gedankt.     

Suessen:新一代EliTe网格圈

Suessen公司的5Star牌网格圈是一种具有特殊矩阵结构的无接缝机织网格圈.这种矩阵结构将在网格圈的整个使用寿命期间表现出明显较好的摩擦性能.而且,它将可靠地防止灰尘和纤维碎屑粘附在网格圈上.     

Electrostatic field computation by an integral equation method

The accuracy of the charge simulation method of calculating electrostatic fields can be improved by optimization techniques that involve the determination of the best location and strength of each individual charge and its image. This paper presents a method that eliminates the optimization of the location of the charges by considering the charges to be distributed in a certain manner on the surface of the object. It is basically an integral technique applied to the method of moments. A simple least-square procedure is employed to reduce the r.m.s. error in potential on the surface. Results are presented to illustrate the greater accuracy achieved and the advantages as well as disadvantages of this method.