Hazard Prevention in Mission Plans for Aerial Vehicles Based on Soft Institutions

Hazard prevention in mission plans requires careful analysis and appropriate tools to support the design of preventive and/or corrective measures. It is most challenging in systems with large sets of states and complex state relations. In the case of sociotechnical systems, hazard prevention becomes even more dicult given that the behaviour of human centric components can at best be partially predictable. In the present article we focus on a specic class of sociotechnical systems namely air spaces containing pilot controlled as well as autonomous aircrafts and introduce the notion of relevant hazards. We also introduce soft institutions as an appropriate basis for analysis, with the aim of addressing relevant hazards. The concept of soft institutions is drawn from specication languages for interaction between agents in multi agent systems but, in our case, is adapted for use in systems that combine human and automated actors.     

FeS/S/FeS(2) redox system and its oxidoreductase-like chemistry in the iron-sulfur world

The iron-sulfur world (ISW) theory is an intriguing prediction regarding the origin of life on early Earth. It hypothesizes that life arose as a geochemical process from inorganic starting materials on the surface of sulfide minerals in the vicinity of deep-sea hot springs. During the last two decades, many experimental studies have been carried out on this topic, and some interesting results have been achieved. Among them, however, the processes of carbon/nitrogen fixation and biomolecular assembly on the mineral surface have received an inordinate amount of attention. To the present, an abiotic model for the oxidation-reduction of intermediates participating in metabolic pathways has been ignored. We examined the oxidation-reduction effect of a prebiotic FeS/S/FeS(2) redox system on the interconversion between several pairs of α-hydroxy acids and α-keto acids (i.e., lactate/pyruvate, malate/oxaloacetate, and glycolate/glyoxylate). We found that, in the absence of FeS, elemental sulfur (S) oxidized α-hydroxy acids to form corresponding keto acids only at a temperature higher than its melting point (113°C); in the presence of FeS, such reactions occurred more efficiently through a coupled reaction mechanism, even at a temperature below the phase transition point of S. On the other hand, FeS was shown to have the capacity to reversibly reduce the keto acids. Such an oxidoreductase-like chemistry of the FeS/S/FeS(2) redox system suggests that it can determine the redox homeostasis of metabolic intermediates in the early evolutionary phase of life. The results provide a possible pathway for the development of primordial redox biochemistry in the iron-sulfur world. Key Words: Iron-sulfur world-FeS/S/FeS(2) redox system-Oxidoreductase-like chemistry. Astrobiology 11, 471-476.     

氧化铝的直接电镀

讨论了在氧化铝基板上的厚膜应用领域中采取直接电镀的方法。研究了建立在钯涂层、碳涂层和导电聚合物基础上的三种直接电镀的方法，测定和比较了它们与传统电镀／ 化学镀技术的操作步序、电镀速度和膜层结合力等技术指标。     

JSF计划办公室将加速JSF备用主发动机的研究进度

JSF计划办公室可能加速GE/艾利逊/罗-罗研究组的YF120-FX备用主发动机的研究进度,这可减少在早期采购JSF时对只有一种发动机的依靠。关于这种发动机进度安排的协商是在5月中旬进行的。据称,如果协调结果像制造商预计的那样,则第一台全尺寸备用主发动机的地面试验将在2002年春进行。虽然这仍在现有计划进度内,但这比发动机制造商原来计划提前约两年。按原来计划,该备选主发动机的第三阶段地面试验将在2000～2004财年期间进行。     

广域差分GPS(WADGPS):未来的导航系统

一般差分GPS(DGPS)在距基准站100公里的范围内,定位精度通常为1—3m,广域差分GPS(WADGGPS)在更广阔的区域内可以获得和DGPS一样的精度,但是可以减少基准站的数量并且大大提高系统的稳妥性。利用WADGPS的试验结果表明,使用6个监视站,最短基线长1632公里的情况下,龄期为10—20s的双频用户,定位精度可达到1.5—4m。     

用于合成孔径雷达图像生成的紧凑的声光处理器

本文描述了合成孔径雷达（ＳＡＲ）实时声光成像器的一种紧凑的实现方法，这种结构通过将所需完成的二维积分分解为两个级的一维积分，以类似于在医学成像中所采用的计算机层析扫描成像的方式形成合成孔径雷达图象。为了降低功耗，所需完成的积分采用交叉式布拉格结构，综合利用光学信号的时间积分与空间积分，在模拟光学域实现，这种结构的时间积分与空间模块是通过一个公用路经干淑仪耦合的，在一个图像形成的旋转的二维ＣＣＤ探测     

广域差分GPS（WADGPS）：未来的导航系统

一般差分GPS（DGPS）在距基准站100公里的范围内，定位精度通常为1-3m，广域差分GPS（WADGPS）在更广阔的区域内可以获得和DGPS一样的精度，但是可以减少基准站的数量并且大大提高系统的稳妥性。利用WADGPS的试验结果表明，使用6个监视站，最短基线长1632公里的情况下，龄期为10-20s的双频用户，定位精度可达到1.5-4m。     

GE/艾利逊公司继续为JAST计划研究发动机

GE公司和艾利逊公司先进发展部(AADC)已获得一项为期一年价值700万美元的合同,以便开始研究能与普惠公司的F119发动机竞争的动力装置。与联合先进攻击技术(JAST)计划办公室签订的这项合同,能使GE公司恢复在JAST计划中的位置。麦道/罗斯诺普-格鲁门/英国宇航公司的JAST小组在1995年初在其JAST设计中不采用F120发动机作为基准的主推进装置时,GE公司失去了在     

联信公司许诺改进LT101发动机

联信公司在今后3年内将为LT101 发动机系列投资1500万美元,以改进该发动机的可靠性和使用户更满意。据该发动机计划经理米勒说:“我们必须保证LT101系列的可靠性与联信公司的其他发动机的可靠性相当。”1994年10月,联信公司采购了来科明公司的燃气涡轮业务后,该公司就开始负责LT101系列。目前虽然有1650多台LT101在使用中,但该发动机已