精密机械零件的统计尺寸公差

精密机械产品的发展要求具有高性能、高可靠性和高质量。如果用设计时减小公关的方法来保证精度，则将难以解决加工和装配中产生的问题。因此需要在采用尽可能大的公差值的民政部下满足精度一文将讨论一些实例，寻找借助于统计尺寸公差降低加工精度要求的办法。     

用于高压动态校准的快开阀装置

介绍一种高压快开阀装置。它可产生３７０ＭＰａ上升时间小于２０μｓ的阶跃压力，用于对高压传感器进行动态校准。     

Protection by WR-2721 and WR-151327 against late effects of gamma rays and neutrons.

Two thiophosphoroate compounds WR-2721 and WR-151327 were assessed for their ability to modify the deleterious effects (life shortening and carcinogenesis) of fission-spectrum neutrons (kerma-weighted mean energy of 0.85 MeV) or gamma rays on B6CF1 hybrid mice. Male and female mice, 200 of each sex per experimental group, were irradiated individually at 110 days of age. Radioprotectors (400 mg/kg of WR-2721 or 580 mg/kg of WR-151327) were administered intraperitoneally 30 min prior to irradiation. Neutron doses were 10 cGy or 40 cGy and gamma ray doses were 206 cGy or 417 cGy. Animals were housed five to a cage; cage locations in the holding rooms were randomized by computer. Animals were checked daily and all deceased animals were necropsied. WR-2721 afforded protection against both neutron- and gamma-ray-induced carcinogenesis and subsequent life shortening. Cumulative survival curves for unirradiated mice of either sex were unaffectecd by protectors. WR-2721 protected irradiated groups against life shortening by approximately 10 cGy of neutrons or 100 cGy of gamma rays. WR-151327 was as effective as WR-2721 against neutron irradiation.     

Carrier-wave interference to Loran-C: a statistical evaluation

Loran-C is a pulsed, hyperbolic radio aid for long-range marine, air, and land navigation. The worldwide expansion of Loran-C, especially in Europe, has focused attention on carrier-wave interference to the system. The effects of a multiplicity of carrier-wave interferers (CWIs) on receiver timing measurement accuracy are considered. Both the phase tracking and the cycle-selection performance of receivers are quantified in terms of the probabilities that they will operate correctly within the arbitrarily set error limits. Characteristic functions (CFs) are used to compute these probabilities. Analyses and results are presented for typical situations. The relative sensitivity of the phase tracking and cycle-selection functions to interfering signals are discussed     

Design of the TRIO system-on-chip for aerospace

Several design and testing aspects of the TRIO smart sensor data acquisition chip, developed by JHU/APL for NASA spacecraft applications are presented. TRIO includes a 10 bit self-corrected analog-to-digital converter (ADC), 16/32 analog inputs, a front end multiplexer with selectable aquisition time, a current source, memory, serial and parallel bus, and control logic. So far TRIO is used in many missions including Contour, Messenger, Stereo, Pluto, and the generic JPL X2000 spacecraft bus.     

一种新型的微机补偿晶体振荡器及开发系统

提出了一种新型的以微处理器为核心的AT切温度补偿晶体振荡器 (MCXO)的设计思想 ,说明了其开发系统的原理 ,给出了最后的实验结果。使用该开发系统得到的这种振荡器可以工作在 - 40℃～ 85℃的环境内 ,频率—温度稳定性≤± 5× 10 - 7。     

Modeling stress strain state of thin shells with a degenerating domain

We consider a possibility to apply the method of analyzing the complex-shaped shells, proposed in [1], for determining the stress strain state of thin shells with a degenerating domain. The results of numerical calculations are presented.     

The finite element approximation of vector fields in curvilinear coordinates

We demonstrate that it is possible to express each component of the displacement vector for the interior point of the finite element (FE) through all components of nodal unknowns in curvilinear coordinates. The effectiveness of the valid technique of vector approximation for displacement fields has been verified on an example.