The Coma of Comet 9P/Tempel 1

As comet 9P/Tempel 1 approaches the Sun in 2004–2005, a temporary atmosphere, or “coma,” will form, composed of molecules and dust expelled from the nucleus as its component icy volatiles sublimate. Driven mainly by water ice sublimation at surface temperatures T > 200 K, this coma is a gravitationally unbound atmosphere in free adiabatic expansion. Near the nucleus (≤ 10² km), it is in collisional equilibrium, at larger distances (≥10⁴ km) it is in free molecular flow. Ultimately the coma components are swept into the comet’s plasma and dust tails or simply dissipate into interplanetary space. Clues to the nature of the cometary nucleus are contained in the chemistry and physics of the coma, as well as with its variability with time, orbital position, and heliocentric distance. The DI instrument payload includes CCD cameras with broadband filters covering the optical spectrum, allowing for sensitive measurement of dust in the comet’s coma, and a number of narrowband filters for studying the spatial distribution of several gas species. DI also carries the first near-infrared spectrometer to a comet flyby since the VEGA mission to Halley in 1986. This spectrograph will allow detection of gas emission lines from the coma in unprecedented detail. Here we discuss the current state of understanding of the 9P/Tempel 1 coma, our expectations for the measurements DI will obtain, and the predicted hazards that the coma presents for the spacecraft. An erratum to this article is available at .     

Sol-gel法制备CuSO4，Cu〈AC）2掺杂SnO2的气敏性能研究

以溶胶-凝胶法（Sol-gel）制备纳米SnO2及其不同比例的铜源掺杂物。采用热分析（TG-DTA），XRD等手段对其产物进行表征，利用静态配气法测试了掺杂产物的气敏性能。实验结果表明：采用Sol-gel法制备掺杂SnO2的气敏性能，同时受铜源和掺杂量的影响，且掺杂产物对乙醇不很敏感，但在150℃工作温度下对0．005％的H2S具有36367倍的高灵敏度。     

氮气介质下钛合金铣削特性的分析研究

提出了用氮气作为切削介质的绿色加工技术,并通过试验设计,分别在干切削和以氮气为介质的切削条件下,对铣削钛合金的铣削力及刀具的后刀面磨损进行了分析研究,最后对试验结果进行了讨论。     

一种改进的概括性卡诺循环燃气轮机及其性能预测分析

基于气体多变压缩以及等温涡轮燃烧技术，提山了一种改进的概括性卡诺循环燃气轮机，通过模型预测分析了其性能，并与传统燃气轮机进行了比较。结果表明，改进的概括性卡诺循环燃气轮机的效率有很大的提高，其循环是一种接近概括性卡诺循环的气体动力循环和一个蒸汽动力循环所构成的联合动力循环，有利于降低NOx的排放。     

点接触CATT齿轮润滑油膜厚度的实验研究

介绍用电阻法测量CATT（Circdar－Arc－Tooth－Trace）齿轮润滑油膜的测量原理、实验设备和方法，研究了油膜沿啮合线和沿齿线的变化规律，得出了可供CATT齿轮设计参考的结论。     

用内文丘里管流量计测量酸气流量

介绍了新型差压装置--内文丘里管的结构、测量原理、技术性能;根据差压式流量计的测量原理,建立了计算酸气流量的数学模型,并将内文丘里管流量计成功地应用于酸气流量的测量.     

氢氧气体爆轰光谱的研究

在以前用摄谱仪研究激液管内氢氧气体爆轰光谱的基础上，用光学多道分析仪（ＯＭＡ光学系统）收集了不同初始压强条件下３００～８００ｎｍ光谱范围氢氧气体爆轰的低分辨和高分辨光谱．     

某型船用燃气轮机的仿真建模

利用部件级建模法建立了某型船用燃气轮机的仿真模型;描述了该仿真模型的功能、计算方法和部件模块设计及程序运行界面。     

对气液二相流音速的进一步研究

测量小药量电雷管爆炸压力波的传播速度,再修正到音速。结果表明:气液二相流音速比单相液体或空气介质低得多,流动机构对音速变化有显著影响。对低气泡率泡状流,音速与均匀流模型导出的结论相一致。随气泡率增加,流动机构改变时,音速值变化很大。