全球遥测数据处理系统

各种实验和试验计划都有一种倾向,即需要多套重复的处理系统以满足它们各自的需要。在某些情况下,不断购进新的设备;在另一些情况下,又不得不使用不可靠的旧设备。“遥测数据处理系统”(TDRS)计划是一项新的技术进展,它为将来的试验计划提供实时的、集中而可靠的数据处理。现代通信技术使这种处理可为在任一地方进行的试验服务,使原来将数据送到工程师手里的时间减少了几天。本文阐明了采用这种系统的必要性,描述了选择所用设备的基本依据,并报道了进展情况。     

美国国防部签订24个有关JAST的合同

美国国防部最近已同美国18家公司签订了总价值为1.278亿美元的24个合同,用于JAST(联合先进攻击技术)计划的方案定义和有关的设计研究。美国三大军用飞机制造商都已接收到一个15个月的合同,为JAST提出一个总体武器系统的方案定义和设计,其中麦道得到的合同价值为282万美元,诺斯罗普公司为241万美元,洛克希德公司为199万美元。在此以前波音已经获得了一个价值为276万美元的合同,也将提出一个武器系统的方案。     

新的维修技术新的发动机性能

介绍了航空发动机的一些维修新技术,包括先进的维修思想、各种涂层以及检测技术,并且认为评价这些新技术的关键是全寿命期成本。     

高压涡轮工作叶片叶型设计研究

针对高压涡轮工作叶片叶栅型面特征,采用可压燃气黏性流2维计算方法对高压涡轮工作叶片叶型进行了气动研究,并通过试验验证了优化设计,得到了叶栅气动设计参数。经与初始叶型对比,优化叶型在各状态下损失特性变化更为平缓,在超临界状态下效率更高,在λ2is=1.20状态下的损失减少了2.8%。该方法缩短了设计时间,并且节省了平面叶栅吹风试验的成本。     

海上发射那些事

正在不久前举行的第二届中国航天高峰论坛上,中国航天科技集团有限公司一位负责人表示,长征火箭海上发射关键技术试验将很快进行,预计2018年就可以面向国际商业用户提供海上发射服务。这就意味着,蔚蓝的海洋很快将成为中国运载火箭新的起飞点,长征火箭将从那里直上九天,奔向深邃的太空。世界海上发射虽然沉寂了一段时间,但是从其发展思路和应用前景来看,应该依然具有相当不错的未来。     

长期记忆是怎么形成的?

正记忆是如何产生的?我们怎么储存记忆?在美国马萨诸塞州剑桥市,诺贝尔奖得主、日本理化学研究所与麻省理工学院神经回路遗传学研究中心所长利根川进正带领研究团队研究记忆痕迹如何在大脑皮层中形成长期记忆。其实记忆痕迹的概念早在100多年前就被提出来了,利根川进的研究团队在《科学》杂志发表的论文证明了这些很早之前就提出的设想,但是有一点与设想的不同:记忆痕迹并非     

TanSat Mission Achievements: from Scientific Driving to Preliminary Observations

The Chinese global carbon dioxide monitoring satellite (TanSat) was successfully launched in December 2016 and has completed its on-orbit tests and calibration. TanSat aims to measure the atmospheric Carbon Dioxide column-averaged dry air mole fractions (X_CO2) with a precision of 4 ppm at the regional scale, and further to derive the CO₂ global and regional fluxes. Progress toward these objectives is reviewed and the first scientific results from TanSat measurements are presented. During the design phase, Observation System Simulation Experiments (OSSE) on TanSat measurements performed prior to launch measurements using a nadir and a glint alternative mode when considering the balance of stable measurements and reduces the flux uncertainty (64%). The constellation measurements of two satellites indicate an extra 10% improvement in flux inversion if the satellite measurements have no bias and similar precision. The TanSat on-orbit test indicates that the instrument is stable and beginning to produce X_CO2 products. The preliminary TanSat measurements have been validated with Total Carbon Column Observing Network (TCCON) measurements and have inter-compared with OCO-2 measurements in an overlap measurement.      

Advances in Researches on the Middle and Upper Atmosphere in 2008-2010

This paper summarizes the results of the researches on the middle and upper atmosphere obtained by Chinese scientists in 2008-2010. The focuses are specifically placed on the researches being associated with ground-based observation capability development, dynamical processes, the property of atmospheric circulation and the chemistry-climate coupling of the middle atmospheric layers.     

Raman spectroscopic analysis of a desert cyanobacterium Nostoc sp. in response to UVB radiation

Cyanobacteria are capable of tolerating environmental extremes. To survive in extreme environments, cyanobacteria have developed the capability to adapt to a variety of stresses. For example, cyanobacteria have adopted a number of strategies with which to survive UV stress, including expression of UV-screening pigments and antioxidant systems. We have previously shown that several antioxidants are significantly expressed in Nostoc sp. by UVB irradiation. We report here that the content of UV-responsive biomarkers such as β-carotene and scytonemin can be easily detected by Fourier transform Raman spectroscopy with use of a small sample size and that the content of β-carotene is dependant on the UVB intensity and exposure time. Our results indicate that Raman spectroscopy may be a helpful tool to analyze UV-protective molecules of cyanobacterium in astrobiological studies without access to large sample sizes and complicated extractions, which are needed by other analytical techniques such as high-performance liquid chromatography and mass spectrometry.     

处理太空垃圾刻不容缓

居住在美国北卡罗来纳州阿什维尔市的NASA退休科学家唐纳德·克斯勒尔经常在自己住宅的后院平台上架起塞莱斯特望远镜观测太空。虽然这台望远镜算不上是最先进的,但却是克斯勒尔最珍爱的物品。1978年,克斯勒尔发表的一篇论文《人造卫星频繁碰撞：碎片带的产生》,使他在航天界名声鹊起。