用于脉冲多普勒雷达EMI检测和角度测量的杂波滤波和处理技术

脉冲多普勒雷达发射一组脉冲重复频率（ＰＲＦ）恒定且相位相参的射频脉冲，叫做相干驻留间隔或ＣＤＩ。由此产生的雷达回波脉冲在雷达接收机／处理机的多普勒滤波器组中被当作一个整体并进行相参积累，以便为在杂波环境中检测小目标提供必要的相参处理增益和速度鉴别能力，相对较长的ＣＤＩ和最小天线扫描速率约束常常使目标照射限制在每个波束驻留时间的几个ＣＤＩ上，由于每个ＣＤＩ回波的功率可能因ＣＤＩ之间射频频率分集（为减     

Spore UV and acceleration resistance of endolithic Bacillus pumilus and Bacillus subtilis isolates obtained from Sonoran desert basalt: implications for lithopanspermia

Bacterial spores have been used as model systems for studying the theory of interplanetary transport of life by natural processes such as asteroidal or cometary impacts (i.e., lithopanspermia). Because current spallation theory predicts that near-surface rocks are ideal candidates for planetary ejection and surface basalts are widely distributed throughout the rocky planets, we isolated spore-forming bacteria from the interior of near-subsurface basalt rocks collected in the Sonoran desert near Tucson, Arizona. Spores were found to inhabit basalt at very low concentrations (相似文献   

玩意儿

苹果的CEO乔布斯说,这世界每天都有一些革命性的产品推出。如果把这句话转变成更好听的话就是:科技,每天都在进步。“玩意儿”是个比李宇春还中性的名词,但相对于科技世界,它就是创意的代名词。它的出现总带来一种新奇,比如说Ipod,再比如说手机,当初无不是从新鲜玩意儿发家的。也许,这些玩意儿并不代表科技的明天,甚至过了本季的流行趋势就成了废品,但至少它会给今天的沉闷注入一些新鲜的空气。     

使用数字电视通道的多媒体信息广播

本文概述了数字电视通道内广播多媒体信息的一种新的系统结构。所提出的方案是建立在ＤＳＭ－ＣＣ（数字存贮媒体指令和控制）功能的基础上，并使用了一种最近拟定的，能有效传送多媒体信息的协议。上述的信息与在ＷＷＷ环境中使用的ＨＴＭＬ文件的特性相同，因此，它可以包含本文、图像声音，和按照超本文编制的动画。     

UV photochemistry of DNA in vitro and in Bacillus subtilis spores at earth-ambient and low atmospheric pressure: implications for spore survival on other planets or moons in the solar system

Two major parameters influencing the survival of Bacillus subtilis spores in space and on bodies within the Solar System are UV radiation and vacuum, both of which induce inactivating damage to DNA. To date, however, spore survival and DNA photochemistry have been explored only at the extremes of Earth-normal atmospheric pressure (101.3 kPa) and at simulated space vacuum (10(-3)-10(-6) Pa). In this study, wild-type spores, mutant spores lacking alpha/beta-type small, acid-soluble spore proteins (SASP), naked DNA, and complexes between SASP SspC and DNA were exposed simultaneously to UV (254 nm) at intermediate pressure (1-2 Pa), and the UV photoproducts cis,syn-thymine-thymine cyclobutane dimer (c,sTT), trans,syn-thymine-thymine cyclobutane dimer (t,sTT), and "spore photoproduct" (SP) were quantified. At 101.3 kPa, UV-treated wild-type spores accumulated only SP, but spores treated with UV radiation at 1-2 Pa exhibited a spectrum of DNA damage similar to that of spores treated at 10(-6) Pa, with accumulation of SP, c,sTT, and t,sTT. The presence or absence of alpha/beta-type SASP in spores was partly responsible for the shift observed between levels of SP and c,sTT, but not t,sTT. The changes observed in spore DNA photochemistry at 1-2 Pa in vivo were not reproduced by irradiation of naked DNA or SspC:DNA complexes in vitro, suggesting that factors other than SASP are involved in spore DNA photochemistry at low pressure.     

Survival and germinability of Bacillus subtilis spores exposed to simulated Mars solar radiation: implications for life detection and planetary protection

Bacterial spores have been considered as microbial life that could survive interplanetary transport by natural impact processes or human spaceflight activity. Deposition of terrestrial microbes or their biosignature molecules onto the surface of Mars could negatively impact life detection experiments and planetary protection measures. Simulated Mars solar radiation, particularly the ultraviolet component, has been shown to reduce spore viability, but its effect on spore germination and resulting production of biosignature molecules has not been explored. We examined the survival and germinability of Bacillus subtilis spores exposed to simulated martian conditions that include solar radiation. Spores of B. subtilis that contain luciferase resulting from expression of an sspB-luxAB gene fusion were deposited on aluminum coupons to simulate deposition on spacecraft surfaces and exposed to simulated Mars atmosphere and solar radiation. The equivalent of 42 min of simulated Mars solar radiation exposure reduced spore viability by nearly 3 logs, while germination-induced bioluminescence, a measure of germination metabolism, was reduced by less than 1 log. The data indicate that spores can retain the potential to initiate germination-associated metabolic processes and produce biological signature molecules after being rendered nonviable by exposure to Mars solar radiation.     

用于CATV光纤／同轴混合网络的基于CDMA的通信框架的初始化协议

描述了用于光纤电缆混合（ＨＦＣ）公用天线电视（ＣＡＴＶ）网络通信系统的基于ＣＤＭＡ通信系统的初始化协议。ＨＦＣ ＣＡＴＶ网络是媒体共享的存取网络，它是利用在光链路终端和用户之间的同轴电缆总线原理实现媒体共享的。为了实现上行方向的存取，可以采用基于ＣＤＭＡ（码分多址）的多址存取方案（１，２，３），然而，在允许上行存取之前，要对连接在电缆总线上的每个电缆调制解调器进行初始化，在允许上行存取之前，要对连     

捆绑火箭和载人飞船的构结强度及环境情报交流会在武夷山召开

捆绑火箭和载人飞船的结构强度及环境情报交流会1991年10月16日至20日在福建省武夷山市召开。交流会是由航空航天工业部航天系统第八情报网和北京宇航学会联合主     

The O/OREOS mission: first science data from the Space Environment Survivability of Living Organisms (SESLO) payload

We report the first telemetered spaceflight science results from the orbiting Space Environment Survivability of Living Organisms (SESLO) experiment, executed by one of the two 10?cm cube-format payloads aboard the 5.5?kg Organism/Organic Exposure to Orbital Stresses (O/OREOS) free-flying nanosatellite. The O/OREOS spacecraft was launched successfully to a 72° inclination, 650?km Earth orbit on 19 November 2010. This satellite provides access to the radiation environment of space in relatively weak regions of Earth's protective magnetosphere as it passes close to the north and south magnetic poles; the total dose rate is about 15 times that in the orbit of the International Space Station. The SESLO experiment measures the long-term survival, germination, and growth responses, including metabolic activity, of Bacillus subtilis spores exposed to the microgravity, ionizing radiation, and heavy-ion bombardment of its high-inclination orbit. Six microwells containing wild-type (168) and six more containing radiation-sensitive mutant (WN1087) strains of dried B. subtilis spores were rehydrated with nutrient medium after 14 days in space to allow the spores to germinate and grow. Similarly, the same distribution of organisms in a different set of microwells was rehydrated with nutrient medium after 97 days in space. The nutrient medium included the redox dye Alamar blue, which changes color in response to cellular metabolic activity. Three-color transmitted intensity measurements of all microwells were telemetered to Earth within days of each of the 48?h growth experiments. We report here on the evaluation and interpretation of these spaceflight data in comparison to delayed-synchronous laboratory ground control experiments.