来自热带雨林的解译

来自热带雨林的解译︹美︺Ｃ芬尼维西钱峰译曾一度为玛雅文明中心地带的危地马拉彼德克斯贝顿热带雨林，就连强盗、窃贼也绕道而行。但在以往的６年中，一支非凡的大型研究队伍抵挡住毒蛇猛兽及当地游击队的侵袭，深入到这一秘密丛林之中去探寻一个秘密：为何这一高度文...     

浅议高等学校人才引进工作

讨论高校师资队伍建设中人才引进工作的重要性,人才引进政策制定,人才招聘,以及建设留住人才的服务平台等.     

陆军机动防空的发展趋势

地面部队的低空防空可分为保护固定发射场和机动设施两种.后者或者安装在机动车辆上限随机动部队进行,或者被牵引着用于保护构筑工事的部队.     

世界标准日祝词

就最广泛的意义来讲,运输意味着把各种人员、技术和组织团体相互联结起来的一个错综复杂的网络。请设想一下,为了乘小汽车、长途汽车或火车以及飞机来加速商务活动或每家每户歼出度假的旅行,为了把     

GENERATION AND APPLICATION OF UNSTRUCTURED ADAPTIVE MESHES WITH MOVING BOUNDARIES

INTRODUCTIONMany engineering applications require thenumerical prediction of strongly unsteady flowsinteracting with moving bodies.A case in pointis that the detailed calculation of sphere motionsin an unsteady field induced by blast waves is akey issue to determine the drag force exerting up-on the sphere by the surrounding gas and,inturn,to reveal the mechanism of unsteady effectson the drag coefficient.To cope with such pro-blems,one should simulate unsteady flows withmoving boundary co…     

Psychological considerations of man in space: problems & solutions

With concrete plans for long duration flight taking form a new impetus is lent to preparing man for this hostile and unnatural environment. Cramped conditions, isolation from family and loved ones, work stress, fear, and incompatibility with fellow crew, are but a few of the problems suffered by astronauts and cosmonauts during their long missions in orbit about the earth.

Although criteria for selection of crew is one aspect of attacking the problem, it has not solved it Notwithstanding good selection, team combination, and counselling before flight, problems have still occurred with unwanted consequences. Incompatibility of team members, far from being the exception, has been frequent. This has been detrímental both physiologically and psychologically for the individual as well as for the operational success and safety of the missions.

Because problems will inevitably occur in future long duration missions, especially when they are of international and multi-cultural nature, the importance of dealing with them is underlined. This paper takes a different approach towards ameliorating these problems, namely that of psychological group training before a mission.     

Effects of microgravity on the binding of acetylsalicylic acid by Rhizobium leguminosarum bv. trifolii

Bacteroids can be induced in vitro by treating growing Rhizobium leguminosarum bv. trifolii with succinic acid or succinic acid structural analogs like acetysalicylic acid. Quantitating bacteroid induction by measuring acetylsalicylic binding under normal (1 g) conditions showed two forms of binding to occur. In one form of binding cells immediately bound comparatively high levels of acetylsalicylic acid, but the binding was quickly reversed. The second form of binding increased with time by first order kinetics and reached saturation in 40 s. Similar experiments performed in the microgravity environment aboard the NASA 930 aircraft showed only one form of binding and total acetylsalicyclic acid bound was 32% higher than at 1 g.     

预测固体推进剂火箭发动机侵蚀燃烧的数值法

对于固体推进剂火箭燃烧可采用一维模型预测固体推进剂火箭发动机的侵蚀燃烧特性。用取决于不同燃烧速率的速度来表示固体推进剂的侵蚀燃烧。数值积分控制偏微分方程就可得到分析结果。使用非定常公式预测固体推进剂侵蚀燃烧特性。计算了各种不同药形的复合推进剂和双基推进剂的侵蚀燃烧特性。测出了各种不同药形装填密度(药柱初始通孔面积与喉面积之比)对压力时间曲线的影响。现有分析指出,装填密度是确定某一特定药形及化学成分的推进剂侵蚀燃烧特性的最重要参数之一。研究表明低燃速推进剂比高燃速推进剂反映出具有较大的侵蚀燃烧效应。同时也表明长方药形与圆柱药形相比具有较大的初始压力峰,相反压力很快就稳定到一般与装填密度无关的平衡压力。     

Lick Observatory Optical SETI: targeted search and new directions

Lick Observatory's Optical SETI (search for extraterrestrial intelligence) program has been in regular operation for 4.5 years. We have observed 4,605 stars of spectral types F-M within 200 light-years of Earth. Occasionally, we have appended objects of special interest, such as stars with known planetary systems. We have observed 14 candidate signals ("triple coincidences"), all but one of which are explained by transient local difficulties. Additional observations of the remaining candidate have failed to confirm arriving pulse events. We now plan to proceed in a more economical manner by operating in an unattended drift scan mode. Between operational and equipment modifications, efficiency will more than double.     

俄国的SA—11防空导弹

SA—11导弹是原苏联在70年代末开始研制的一种防空导弹,它还有一种舰载型称为SA—N—7。 SA—11是单级固体导弹,弹长5.5m,弹径400mm,弹重690kg,采用半主动单脉冲雷达寻的制导方式,装载70kg重的高爆/预制破片战斗部,采用无线电—电动近炸引信。该导弹的的总体布局类似于美国的RIM—66标准导弹,采用较长的小展弦比弹翼和十字型尾翼。