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371.
靶场安全问题随导弹性能的提高日趋重要。在发射场附近这一问题更为突出,因为这里导弹爆炸能量最大。诸如雷达、GPS外测系统和光测因多种原因在这里用得不多,故需要一种设备能在导弹起飞后头几秒内提供有用的外测数据。该设备能提供从发射台起飞直到120秒内的导弹偏离理论弹道的数据。 本文叙述的外测系统利用了无线电干涉仪的原理,从两个精密间隔的天线提取相位差测量值。这些测量值送往“试验显示设施”,转换成常用的角偏差曲线,供靶场安全人负使用。 本文介绍了无线电干涉仪系统的基本概念,这种特殊外测系统的设置和使用情况。并详细介绍了这种设备的射前演练、设置以及实时显示的设置和最终数据产品的输出。 相似文献
372.
We report the discovery of fossilized filamentous structures in samples of the lithified, volcaniclastic apron of Gran Canaria, which were obtained during Leg 157 of the Ocean Drilling Program (ODP). These filamentous structures are 2-15 μm in diameter and several hundred micrometers in length and are composed of Si, Al, Fe, Ca, Mg, Na, Ti, and C. Chitin was detected in the filamentous structures by staining with wheat germ agglutinin dye conjugated with fluorescein isothiocyanate (WGA-FITC), which suggests that they are fossilized fungal hyphae. The further elucidation of typical filamentous fungal morphological features, such as septa, hyphal bridges, and anastomosis and their respective sizes, support this interpretation. Characteristic structures that we interpreted as fossilized spores were also observed in association with the putative hyphae. The fungal hyphae were found in pyroxene phenocrysts and in siderite pseudomorphs of a basalt breccia. The fungal colonization of the basalt clasts occurred after the brecciation but prior to the final emplacement and lithification of the sediment at ～16-14 Ma. The siderite appears to have been partially dissolved by the presence of fungal hyphae, and the fungi preferentially colonized Fe-rich carbonates over Fe-poor carbonates (aragonite). Our findings indicate that fungi may be an important geobiological agent in subseafloor environments and an important component of the deep subseafloor biosphere, and that hydrothermal environments associated with volcanism can support a diverse ecosystem, including eukaryotes. 相似文献
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已经用砷化镓制作出高 Q 表面波谐振器,并且用来控制振荡器的频率。由于砷化镓既是压电材料,又是半导体材料,因此有可能用来对全单片振荡器进行电调节。曾对半绝缘基片上的表面波谐振器的参数进行了研究。这些器件既有刻槽,又有金属电极反射栅。可调节频率的声表面波谐振器被制作在用肖脱基势垒电极作为谐振器栅的外延砷化镓基片上。调节频率并不显著改变介入损耗。两端对谐振器的介入损耗值典型的在15和20dB 之间,在180兆赫的负载 Q 值高达12000。虽然砷化镓的延迟温度系数为52ppm/℃,但是,可以通过加一层 Au/SiO_2对砷化镓延迟线进行温度补偿。 相似文献
375.
为了在一定的跟踪精度范围内且存在不确定性因素的情况下控制机器人跟踪设定的轨迹,给出了一种基于控制器输出误差法的自适应模糊控制法来控制机器人手臂.采用梯度下降法调节部分或全部参数以减小输出误差.该方法被应用于5自由度机器人控制系统中,仿真结果显示模糊逻辑控制器参数得到了实时调整,该方法有效. 相似文献
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377.
<正>未来可能应用于MRO领域的新技术有很多,有的是受上游产业影响而发展的,有的是新技术的直接应用,如复合材料修理、增材制造、数字孪生、预测性维修、增强现实、自动化、机器人等等,但这些技术真正应用于MRO领域后会是何种程度,应用中还存在哪些障碍,亦或是其他新的商业模式还会催生出哪些新的技术,这些都应该提前思考。 相似文献
378.
With several attractive properties, rotary lip seals are widely used in aircraft utility system, and their reliability estimation has drawn more and more attention. This work proposes a reliability estimation approach based on time-varying dependence analysis. The dependence between the two performance indicators of rotary lip seals, namely leakage rate and friction torque, is modeled by time-varying copula function with polynomial to denote the time-varying parameters, and an efficient copula s... 相似文献
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Pfiffner SM Onstott TC Ruskeeniemi T Talikka M Bakermans C McGown D Chan E Johnson A Phelps TJ Le Puil M Difurio SA Pratt LM Stotler R Frape S Telling J Lollar BS Neill I Zerbin B 《Astrobiology》2008,8(3):623-638
A scientific drilling expedition to the High Lake region of Nunavut, Canada, was recently completed with the goals of collecting samples and delineating gradients in salinity, gas composition, pH, pe, and microbial abundance in a 400 m thick permafrost zone and accessing the underlying pristine subpermafrost brine. With a triple-barrel wireline tool and the use of stringent quality assurance and quality control (QA/QC) protocols, 200 m of frozen, Archean, mafic volcanic rock was collected from the lower boundary that separates the permafrost layer and subpermafrost saline water. Hot water was used to remove cuttings and prevent the drill rods from freezing in place. No cryopegs were detected during penetration through the permafrost. Coring stopped at the 535 m depth, and the drill water was bailed from the hole while saline water replaced it. Within 24 hours, the borehole iced closed at 125 m depth due to vapor condensation from atmospheric moisture and, initially, warm water leaking through the casing, which blocked further access. Preliminary data suggest that the recovered cores contain viable anaerobic microorganisms that are not contaminants even though isotopic analyses of the saline borehole water suggests that it is a residue of the drilling brine used to remove the ice from the upper, older portion of the borehole. Any proposed coring mission to Mars that seeks to access subpermafrost brine will not only require borehole stability but also a means by which to generate substantial heating along the borehole string to prevent closure of the borehole from condensation of water vapor generated by drilling. 相似文献