ESA再入探测器的某些空气热动力问题(英文)

给出了两种不同的再入飞行器:充气的再入和下滑演示器(IRDT)和Huygens。两者的任务都涉及在靠近轨道的条件下再入并均已于2005年完成。概述了IRDT的使命和具体设计问题, 综述了IRDT最近飞行的初步结果和ESTEC估计Huygens受到的辐射通量采用的方法。

Multiplex PCR for Identification and Detection of Cassava Mosaic Begomoviruses in Togo

Cassava mosaic disease (CMD) caused by Cassava Mosaic Begomoviruses (CMBs) is one of the most devastating crop diseases and a major constraint for cassava production. In order to ensure surveillance for epidemic prevention, low-cost diagnostic tools are appropriate for large-scale testing of cassava viruses. Multiplex PCR diagnosis is one approach that can reduce diagnostic costs and delays. A multiplex PCR approach was developed for simultaneous detection of African cassava mosaic virus (ACMV), East African Cassava Mosaic Virus and East African cassava mosaic Cameroon virus (EACMV/CM) in Togo CMD-infected cassava leaves. Three primers pairs were used to target their respective viruses in a single tube PCR. Multiplex PCR detected ACMV, EACMV and EACMV/CM in plant DNA extracts prepared from cassava leaves infected with CMB. The primers amplified 783 bp specific to ACMV, 650 bp specific to EACMV and 560 bp specific to EACMCV/CM in both uniplex and multiplex formats. Multiplex PCR is an excellent tool for the effective control of cassava diseases. .

γ-TiAl基金属间化合物合金的显微组织与内应力研究

通过采用不同的热处理工艺，对锻造后的ＴｉＡｌ基金属间化合物进行热处理，得到了含有不同等轴 γ及片层 （γ＋α）时体积比的双态组织，并采用Ｘ射线衍射技术对试样进行内应力测定。实验结果表明，ＴｉＡｌ基金属间化合物合 金中的内应力随显微组织及α２的体积分数的变化而变化，并对实验结果及产生内应力的原因进行了分析。

γ-TiAl基金属间化合物近γ组织强度的细观力学分析

通过选用不同 Al含量的 γ- Ti Al基金属间化合物及采用适当的热加工工艺及热处理工艺 ,获得了几种含有不同α2 体积含量的近 γ组织 ,采用室温拉伸试验研究 α2 相的含量对合金力学性能的影响。然后利用细观力学的方法分析了含有不同 α2 体积含量的合金的强度随外载的变化关系。结果表明 ,α2 相的体积含量对合金的强度有较大的影响 ,所选用细观力学模型的计算结果和试验结果吻合较好 。

薄膜几种重要力学性能的评价

提出了一种利用X射线应力分析技术和应变电测法测量附着膜的等效应力———等效单轴应变、屈服强度和加工硬化指数的方法。利用该方法测得一种厚度为2.5μm的TiN膜的条件屈服点σ0.1和σ0.2分别等于4.2GPa和4.4GPa,加工硬化指数n为0.36;对于一种厚度为2.4μm的铜膜,得到σ0.1=328MPa,σ0.2=415MPa,n=0.62。利用无应变剥层技术逐层剥离薄膜,同时测量基片曲率半径的变化,由此测得了一种厚度为2.3μm的TiN膜的残余应力沿层深分布。用新建立的一种利用X射线应力分析法测量薄膜泊松比的技术,测出一种TiN膜的泊松比等于0 27。给出了测量陶瓷膜的杨氏模量的设想。

TiN附着膜的应力-应变关系

利用等离子体辅助化学气相沉积法(PACVD)在60Mn钢基片上沉积2.5μm厚的TiN膜,借助X射线应力分析技术和微拉伸设备,测量该附着膜纵向(加载方向)应力和横向应力及外载应变,进而求其等效应力-等效单轴应变关系,并由此算得它的条件屈服点σ_(0.1)和σ_(0.2)分别为4.2和4.4 GPa,加工硬化指数为0.36,用纳米压痕仪测得其硬度为25 GPa,弹性模量为420 GPa,TiN膜在拉伸过程中发生了塑性变形。

Combined Remote Sensing and GIS Techniques for Studying the Large Roman Urban System Expansion during the Last Twenty Years

Several factors may contribute to on-going challenges for spatial planning and policy in megacities such as Rome, including rapid population shifts, poorly organized areas, and lack of data through which monitoring urban growth and land use change. This research was conducted to examine past and current effects of the urbanization process, occurred over the large Roman urban system, on the basis of multi-source and multi-temporal optical remote sensing (RS) data, collected between 1990 and 2013. These changes were then validated via Geographic Information System (GIS) techniques, in a particular procedure applied to urban land/agricultural transformations. The proposed approach, based on geo-statistical methods, was used to calculate the index of innovative space (AP Index), useful for the monitoring of the urban sprawl phenomenon. Strong evidence of urban expansion over the north-eastern quarter of the city, accompanied by environmental degradation and loss of biodiversity, is provided. Urban infill developments are expected to emerge in the south-eastern areas too, and these might increase urban pressure as well. In conclusion, RS and GIS technologies together with ancillary data can be used to assist decision makers in preparing future plans to find out appropriate solutions to urbanization encroachment.

Traffic Fluxes and Urban Congestion: A Simple Approach with the <i>Attractors</i>’ Method

Situations of heavy and congested traffic in urban areas have been analysed by using a statistical approach based on both the identification of specific locations that attract drivers in a multipoint-to-multipoint traffic structure and their classification (attractor’s value) as a function of the number of people visiting them by car in different time ranges. By using a Kernel Density Estimation (KDE) function, attractors’ distribution density values have been estimated and then integrated with nodal and critical traffic points and traffic density in a “congestion” map. Finally, cross-comparing congestion values with the location of buildings, the road network and the Corine Land Use/Land Cover environmental classification, a “Quality of Life” map has been generated. The authors use this term because the congestion of traffic flows, with all the problems that it entails (such as long travel time, air and acoustic pollution, and so on) is a good indicator of the quality of life, especially in small towns. Results show that this type of “off-line” analysis would allow administrators to identify, quickly and at low cost, areas where citizens’ quality of life is most affected by traffic noise and jumps and, hence, to focus costly ground measurements and interventions primarily there.

Traffic Attractors and Congestion in the Urban Context, the Case of the City of Rome

Traffic flows form a complex system, especially in the context of urban sprawl. Direct estimation of traffic flows requires significant efforts and knowing in advance where to focus the study and where to place tools to directly measure traffic flows, and consequently traffic congestion could lead to significant savings in time and money. In the case of Rome municipality, we have monitored a situation in which a very high rate of urban fragmentation has occurred in the last 30 years, making the direct estimation of traffic difficult. The work described here can help to solve the problem of estimating traffic flows and in particular the congestion phenomenon through a very cheap approach by using remote sensing and geographical information system technology. This method is based on the identification of attractor points that draw traffic flows such as malls, schools, offices, shops, etc. that is to say, points in a territory that attract a certain number of people with vehicles (estimated with a scale) in specific periods of the day. The identification of those points and the calculation of the urban density through the satellite image processing have allowed the creation of a congestion map for the study area. Then the road network and the buildings have been classified according to the congestion values. The results highlight the most critical and congested areas that affect the traffic flows and impact the quality of life.

X-ray elastic constant determination and residual stress of two phase TiAl-based intermetallic alloy

To evaluate the residual stress in TiAl based alloys by X ray diffraction, X ray elastic constants (REC) of a γ TiAl alloy were determined. From these results, the stress state of a given phase in a duplex TiAl based alloy under a uniaxial tensile loading has been characterized by X ray diffraction. The results show that the X ray elastic constants and the microscopic stresses of the given phase are different from the apparent elastic constants and the macroscopic stresses of the alloy. The reason of the different distribution of the alloy was also discussed. [

Psychological problems related to capillary blood glucose testing and insulin injection among diabetes patients

Objective:This review is aimed at explaining the psychological problems related to capillary blood glucose(CBG)testing and insulin injection,as well as recommending essential strategies to solve the fear thereof.Methods:Databases,including PubMed,Cumulative Index of Nursing and Allied Health Literature(CINAHL),Scopus,and Google Scholar,were searched to extract the relevant articles.Initially,the terms used to retrieve related studies were"fear of blood glucose monitoring","anxiety capillary blood glucose testing and insulin injection","psychological problems on blood glucose monitoring and insulin injection","diabetes management",and"diabetes mellitus".Results:Results showed that the psychological problems related to CBG testing and insulin injection were associated with the stress and depression experienced during diabetes self-monitoring of blood glucose.This psychological issue has its impacts such as nonadherence to medication as well as a lack of self-discipline in terms of CBG testing and insulin injection.Inadequate information,inappropriate perception,and pain/discomfort during pricking of fingers were the main reasons for the psychological issues in CBG testing and self-injection of insulin.Conclusions:The expected benefits of this review include the explanation of the issues related to the psychological problems in CBG testing and insulin injection among type 2 diabetes mellitus(T2DM)patients.This review article also provides the recommendations on providing counseling and empowering the patients on CBG monitoring and insulin injection.Moreover,family members should provide psychological support to reduce fear,anxiety,and distress arising from CBG testing and insulin injection.

Magnetospheric Boundary Layer Structure and Dynamics as Seen From Cluster and Double Star Measurements

In this review,we discuss the structure and dynamics of the magnetospheric LowLatitude Boundary Layer(LLBL)based on recent results from multi-satellite missions Cluster and Double Star.This boundary layer,adjacent to the magnetopause on the magnetospheric side,usually consists of a mixture of plasma of magnetospheric and magnetosheath origins,and plays an important role in the transfer of mass and energy from the solar wind into the magnetosphere and subsequent magnetospheric dynamics.During southward Interplanetary Magnetic Field(IMF)conditions,this boundary layer is generally considered to be formed as a result of the reconnection process between the IMF and magnetospheric magnetic field lines at the dayside magnetopause,and the structure and plasma properties inside the LLBL can be understood in terms of the time history since the reconnection process.During northward IMF conditions,the LLBL is usually thicker,and has more complex structure and topology.Recent observations confirm that the LLBL observed at the dayside can be formed by single lobe reconnection,dual lobe reconnection,or by sequential dual lobe reconnection,as well as partially by localized cross-field diffusion.The LLBL magnetic topology and plasma signatures inside the different sub-layers formed by these processes are discussed in this review.The role of the Kelvin-Helmholtz instability in the formation of the LLBL at the flank magnetopause is also discussed.Overall,we conclude that the LLBL observed at the flanks can be formed by the combination of processes,(dual)lobe reconnection and plasma mixing due to non-linear Kelvin-Helmholtz waves.

Neutralized solar energetic particles for SEP forecasting:Feasibility study of an innovative technique for space weather applications

Energetic neutral atoms(ENAs)are produced by the neutralization of energetic ions formed by shock-accelerated gradual solar energetic particle events(SEP).These high-energy ENAs(HENAs)can reach the Earth earlier than the associated SEPs and thus can provide information about the SEPs at the lower corona.The HENA properties observed at Earth depend on the properties of the coronal mass ejection(CME)-driven shocks that accelerate the SEPs.Using a model of HENA production in a shock-accelerated SEP event,we semi-quantitatively investigate the energy-time spectrum of HENAs depending on the width,propagation speed,and direction of the shock,as well as the density and ion abundances of the lower corona.Compared to the baseline model parameters,the cases with a wider shock width angle or a higher coronal density would increase the HENA flux observed at the Earth,while the case with an Earthpropagating shock shows a softened HENA spectrum.The comparison of expected HENA fluxes in different cases with a flight-proven ENA instrument suggests that solar HENAs can feasibly be monitored with current technologies,which could provide a lead time of 2−3 hours for SEPs at a few MeV.We propose that monitoring of solar HENAs could provide a new method to forecast shock-driven SEP events that are capable of significant space weather impacts on the near-Earth environment.

Enhanced Urban Sprawl Monitoring over the Entire District of Rome through Joint Analysis of ALOS AVNIR-2 and SENTINEL-2A Data

Based on the continuation of our past study, the present analysis is conducted to examine recent effects of the urbanization process occurring over the entire district of Rome. Overlays of ALOS AVNIR-2 and SENTINEL-2A satellite images, collected over a 6 years period, were validated via Geographic Information System (GIS) techniques, in a particular procedure applied to urban land and agricultural transformations. The use of Copernicus SENTINEL-2A imagery has improved the previous results on urban processes, by reducing the uncertainty of the discrimination of land cover classes and facilitating the photo-interpretation. Statistical analysis was performed via the Urban Area Profile index in order to quantify the sprawl phenomenon, by defining several landscape metrics. This work, to be enriched in the future by means of complementary information available from Copernicus radar sensors, like the one onboard Sentinel-1, completes the series of observations on land use published by the Italian National Institute for Environmental Protection and Research, which stopped back in 2008.

魅影如幻——外太空精彩天文摄影赏析

NASA,是美国国家航空航天局的简称,是美国负责太空计划的政府机构。ESA,是欧洲数国政府间的空间探测和开发组织。现如今,能在外太空依靠强大的光学望远镜做太空摄影的机构,最牛的恐怕只有NASA、ESA了。因为它们拥有最先进的航空航天技术,在载人空间飞行、航空学、空间科学等方面有很大的成就。

An Event Horizon Imager(EHI) Mission Concept Utilizing Medium Earth Orbit Sub-mm Interferometry

Submillimeter interferometry has the potential to image supermassive black holes on event horizon scales,providing tests of the theory of general relativity and increasing our understanding of black hole accretion processes.The Event Horizon Telescope(EHT) performs these observations from the ground,and its main imaging targets are Sagittarius A~* in the Galactic Center and the black hole at the center of the M87 galaxy.However,the EHT is fundamentally limited in its performance by atmospheric effects and sparse terrestrial(u,v)-coverage(Fourier sampling of the image).The scientific interest in quantitative studies of the horizon size and shape of these black holes has motivated studies into using space interferometry which is free of these limitations.Angular resolution considerations and interstellar scattering effects push the desired observing frequency to bands above 500 GHz.This paper presents the requirements for meeting these science goals,describes the concept of interferometry from Polar or Equatorial Medium Earth Orbits(PECMEO) which we dub the Event Horizon Imager(EHI),and utilizes suitable space technology heritage.In this concept,two or three satellites orbit at slightly different orbital radii,resulting in a dense and uniform spiral-shaped(u,v)-coverage over time.The local oscillator signals are shared via an inter-satellite link,and the data streams are correlated on-board before final processing on the ground.Inter-satellite metrology and satellite positioning are extensively employed to facilitate the knowledge of the instrument position vector,and its time derivative.The European space heritage usable for both the front ends and the antenna technology of such an instrument is investigated.Current and future sensors for the required inter-satellite metrology are listed.Intended performance estimates and simulation results are given.