Heavy-ion induced genetic changes and evolution processes.

On Moon and Mars, there will be more galactic cosmic rays and higher radiation doses than on earth. Our experimental studies showed that heavy ion radiation can effectively cause mutation and chromosome aberrations and that high-LET heavy-ion induced mutants can be irreversible. Chromosome translocations and deletions are common in cells irradiated by heavy particles, and ionizing radiations are effective in causing hyperploidy. The importance of the genetic changes in the evolution of life is an interesting question. Through evolution, there is an increase of DNA content in cells from lower forms of life to higher organisms. The DNA content, however, reached a plateau in vertebrates. By increasing DNA content, there can be an increase of information in the cell. For a given DNA content, the quality of information can be changed by rearranging the DNA. Because radiation can cause hyperploidy, an increase of DNA content in cells, and can induce DNA rearrangement, it is likely that the evolution of life on Mars will be effected by its radiation environment. A simple analysis shows that the radiation level on Mars may cause a mutation frequency comparable to that of the spontaneous mutation rate on Earth. To the extent that mutation plays a role in adaptation, radiation alone on Mars may thus provide sufficient mutation for the evolution of life.     

晚清修律对封建正统法律思想的改易

自汉朝以来，以儒家法律思想为主的封建正统法律思想在中国法律史上一直处于独尊独尚的地位。然而，清廷统治的最后十年，一场史无前例的变法修律，却首开吸收西方资产阶级法律思想入律之先河，第一次对封建正统法律思想的根本原则，基本内容等进行了突破、改易。尽管这些突破是有限的，但它足以表明晚清修律终于结束了两千多年来封建正统法律思想的垄断统治，终于使中国古代法律冲破了旧的樊篱，迈上了近现代型的历史轨道，为新的法律思想的发展完善开拓出了广阔的空间。     

Deceleration and heating constrained footprint of shuttle vehicles

With increasing frequency in shuttle operation, it is of interest to have more than one or two landing fields within the boundary of the reachable area of the reentry vehicle. This boundary, called the footprint, depends on the aerodynamic characteristics of the vehicle and is severely restricted by the deceleration and heating constraints imposed upon the atmospheric reentry trajectory. This paper gives a general assessment of the footprint as a function of various deceleration and heating constraints. The difficulties in the computation of the three-dimensional reentry trajectories with optimal modulation in both the angle-of-attack and the bank angle are alleviated by the following devices: (a) nondimensionalizing of the equations of motion and use of the density as the altitude variable; (b) use of the classical integrals of the motion; (c) transformation of the adjoint variables into physical variables; and (d) spherical rotation of the coordinates.     

圆度仪被测工件的自动对中

对Ｙ９０２５—Ｂ型圆度仪中被测工件的自动对中部分作了较为详细的介绍，其中包括基本工作原理、数据采集、电机控制及有关的软件框图等。该系统能自动把被测工件的偏心调至微米级。     

高旋转数下45°斜肋回转通道平均换热特性研究

为了更加深入地研究涡轮叶片回转通道的换热特性,研究了高旋转数下带45°斜肋回转通道的平均换热特性。在通道进口雷诺数从10000~70000,旋转数从0~2.07的范围内,实验研究了旋转状态下,方形截面带45°斜肋U型通道径向出流与径向入流两个流程四个侧面在0°,22.5°和45°三个安装角下的平均换热系数。研究结果表明:45°斜肋增强了通道换热,减弱了旋转对换热的影响;由于浮升力作用在肋间二次流上,导致通道内外侧出现临界回流现象;转角减弱了第一通道旋转对换热的影响,增强了第二通道旋转对换热的影响,其影响在低旋转数下并不显著,在高旋转数下开始变得明显。     

大型客机一体化试飞改装设计方法研究

研究了大型客机试飞改装的要求和特点,提出了一体化试飞改装的设计方法,结合其在型号研制过程中的具体应用情况,具体阐述了一体化改装设计的方法及关键技术点。     

最后圣殿的陨落？费卢杰之围攻

科技总是最能在单纯的环境发挥作用，1991年海湾战争即充分展现了优势科技武力在开阔地带对于劣势科技武力催枯拉朽般的威力。打从2003年第二次海湾战争爆发，各方无不预期伊拉克部队或出于无力，或出于无愿，部将无法对美军的进击构成任何有意义的阻碍。于是乎复杂的城镇战（MOUT）环境就成了萨达姆眼下削弱美军科技优势的一张王牌，让美军身陷巴格达的都市丛林，使之成为一个教美军血流成河的“斯大林格勒”。美军优势科技武力能否经得起城镇战的考验呢？多少令人意外的是，美军轻易推倒了萨达姆政府，各方所担忧的惨烈城镇战反倒没有发生。     

Functional models for space power electronic circuits

Presented here is a new approach to model power electronic components so that system level issues of large space power systems can be studied. To demonstrate this approach, the models for two major power electronic components in the space station power system are described. The new models are useful not only in system level studies but also in the design/analysis of particular components     

大口径反射镜在平行光管中的安装方法

文章介绍了3种平行光管中大口径反射镜的安装方法，并通过力学分析进行比较，给出了各自的优缺点。