前沿芯材:多功能芯结构

<正>等距折叠蜂窝结构,即折叠芯材,是一种用于轻质夹层结构、具有优异性能的新型芯材。这种结构是运用基本的手工折纸方法由平面薄片材料折叠得到的,并没有对原材料进行剪裁、胶结或牵伸。这种等距折叠方法可用于高品质的材料,并且可     

联邦快递公司的自动灭火系统

<正>美国联邦快递公司(FedEx)开发出一种新的灭火系统(FSS),可以安装在越洋飞行的远程宽体飞机上。到2011年初,FedEx将在其59架MD-11货机上的安装该系统,该公司还计划在新接收的波音777货机上安装该灭火系统。     

Sikkim's Teesta River fog, mist and dust particle monitoring using monostatic LIDAR

Fog, mist, and atmospheric dust particles, having the dimension of one micrometer or less, play an important role in the deterioration of visibility, as well as in causing local warming in the atmosphere. With an attempt to reduce the deterioration, a scientific approach has to be taken to determine their origins. A monostatic LIDAR may be one of the best instruments for such work. The authors are tempted to develop such a LIDAR for fog, mist, and dust particle monitoring over River Teesta at Sikkim. LIDAR is an acronym for Light Detection And Ranging. What can we do with LIDAR? Measure distance, measure speed, measure rotation, measure chemical composition and concentration, and measure cross-sections of the targets. The digital technique is always utilized for its development which results in better security, lower power consumption, higher power efficiency, higher reliability, lower transmitter power, lower multipath effect, higher interference suppression as compared to an analog system. The commercial systems like disdometer, rain radar, mobile robot, etc., utilizing LIDAR principles are operational in different parts of the world. The authors are highly motivated for such LIDAR development and their development effort follows.     

A Modification to Improve the Inverse Filter of Senmoto and Childers

An inverse filter, contained in a recently published paper by Senmoto and Childers, is improved by the application of a shaping function derived by Turin in an earlier paper.     

X-ray and optical variability at the hour timescale for 1E 0630+178 (GEMINGA) and its proposed optical couterpart

Einstein and EXOSAT data on the soft X-ray source IE 0630+178, the proposed counterpart of the -ray source GEMINGA, are analyzed for variability on the time scale of one to three hours. The EXOSAT September 1983 data, with an uninterrupted strech of over 10 hours offer the most interesting case. In parallel, a similar analysis is presented for the first time, for the optical data of the m_V21 proposed counterpart. About 30 CCD exposures, of 15 min. each, taken over two consecutive nights at the 3.6 m CFH telescope, yield evidence of variability, when compared to the data of similar nearby objects in the field.Visiting astronomer at the Canada-France-Hawaii Telescope, operated by the National Concil of Research, Canada, the Centre National de la Recherche Scientifique, France, and the University of Hawaii.     

Investigation of Satellite Trace (ST) and Multi-reflected Echo (MRE) ionogram signatures and its possible correlation to nighttime spread F development from Cyprus over the solar mini-max (2009–2016)

Multi-reflected echoes (MREs) and satellite traces (STs) are referred in literature as ionogram signatures of Travelling Ionospheric Disturbances (TIDs) which is a phenomenon that apparently drives spread F development mainly at nighttime mid-latitude ionosphere. A long-term statistical study has been undertaken to investigate the morphological aspect of these signatures over the lower midlatitude European station of Nicosia, Cyprus (35.19°N, 33.38°E geographic; magnetic dip. 29.38°N) by inspecting all ionograms recorded by the DPS-4D digisonde in the interval 2009–2016. The results underline the systematic manifestation of these TID signatures over Cyprus with a possible (although not quite clear) solar activity dependence and a distinctive seasonal and diurnal occurrence rate with a seasonal peak of STs during summer and of MREs during January to April. Based on the experimental results of the present study, the seasonal occurrence rate of MREs and STs is found to increase by 75% and 56% during high solar activity periods. Satellite traces are well known ionogram signatures of TIDs and mostly correlated to the nighttime spread F formation. The occurrence of mid-latitude spread Fs over European longitude sector normally increases during summer. The occurrences of TIDs are also prominent at this interval of the year over nighttime mid-latitude ionosphere. The presence of MREs as an ionogram signature of TIDs over mid-latitude ionosphere is unique in nature.