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。     

The Interstellar Boundary Explorer (IBEX):

The Interstellar Boundary Explorer (IBEX) mission is exploring the frontiers of the heliosphere where energetic neutral atoms (ENAs) are formed from charge exchange between interstellar neutral hydrogen atoms and solar wind ions and pickup ions. The geography of this frontier is dominated by an unexpected nearly complete arc of ENA emission, now known as the IBEX ‘Ribbon’. While there is no consensus agreement on the Ribbon formation mechanism, it seems certain this feature is seen for sightlines that are perpendicular to the interstellar magnetic field as it drapes over the heliosphere. At the lowest energies, IBEX also measures the flow of interstellar H, He, and O atoms through the inner heliosphere. The asymmetric oxygen profile suggests that a secondary flow of oxygen is present, such as would be expected if some fraction of oxygen is lost through charge exchange in the heliosheath regions. The detailed spectra characterized by the ENAs provide time-tagged samples of the energy distributions of the underlying ion distributions, and provide a wealth of information about the outer heliosphere regions, and beyond.     

Earth's earliest biosphere-a proposal to develop a collection of curated archean geologic reference materials

The discovery of evidence indicative of life in a Martian meteorite has led to an increase in interest in astrobiology. As a result of this discovery, and the ensuing controversy, it has become apparent that our knowledge of the early development of life on Earth is limited. Archean stratigraphic successions containing evidence of Earth's early biosphere are well preserved in the Pilbara Craton of Western Australia. The craton includes part of a protocontinent consisting of granitoid complexes that were emplaced into, and overlain by, a 3.51-2.94 Ga volcanigenic carapace - the Pilbara Supergroup. The craton is overlain by younger supracrustal basins that form a time series recording Earth history from approximately 2.8 Ga to approximately 1.9 Ga. It is proposed that a well-documented suite of these ancient rocks be collected as reference material for Archean and astrobiological research. All samples would be collected in a well-defined geological context in order to build a framework to test models for the early evolution of life on Earth and to develop protocols for the search for life on other planets.     

The first cell membranes

Organic compounds are synthesized in the interstellar medium and can be delivered to planetary surfaces such as the early Earth, where they mix with endogenous species. Some of these compounds are amphiphilic, having polar and nonpolar groups on the same molecule. Amphiphilic compounds spontaneously self-assemble into more complex structures such as bimolecular layers, which in turn form closed membranous vesicles. The first forms of cellular life required self-assembled membranes that were likely to have been produced from amphiphilic compounds on the prebiotic Earth. Laboratory simulations show that such vesicles readily encapsulate functional macromolecules, including nucleic acids and polymerases. The goal of future investigations will be to fabricate artificial cells as models of the origin of life.     

美国开始进行长航时无人机的武器投放试验

普罗透斯又称"希腊海神"飞机,是由美国缩比复合材料公司研制的,早先曾被用于科学仪表测试,后来被广泛用于美国防部中空长航时无人机性能试验和其他先进技术的验证工作,并成为一种在无人机发展项目中的低风险、相对廉价的试验飞机.     

E-10机载雷达与高能微波武器

如今的MP—RTIP雷达不仅可对如巡航导弹大小的隐身目标进行定位和瞄准,还可直接作为攻击性电子战武器使用;高能微波武器的精确性要求比激光武器低,成本又比之低廉。这些性能优势使它们在定向能武器发展方向上迅速超越激光武器,成为研发人员高度关注的技术领域之一。     

Calculation of the Initial Magnetic Field for Mercury’s Magnetosphere Hybrid Model

Several types of numerical models are used to analyze the interactions of the solar wind flow with Mercury’s magnetosphere, including kinetic models that determine magnetic and electric fields based on the spatial distribution of charges and currents, magnetohydrodynamic models that describe plasma as a conductive liquid, and hybrid models that describe ions kinetically in collisionless mode and represent electrons as a massless neutralizing liquid. The structure of resulting solutions is determined not only by the chosen set of equations that govern the behavior of plasma, but also by the initial and boundary conditions; i.e., their effects are not limited to the amount of computational work required to achieve a quasi-stationary solution. In this work, we have proposed using the magnetic field computed by the paraboloid model of Mercury’s magnetosphere as the initial condition for subsequent hybrid modeling. The results of the model have been compared to measurements performed by the Messenger spacecraft during a single crossing of the magnetosheath and the magnetosphere. The selected orbit lies in the terminator plane, which allows us to observe two crossings of the bow shock and the magnetopause. In our calculations, we have defined the initial parameters of the global magnetospheric current systems in a way that allows us to minimize paraboloid magnetic field deviation along the trajectory of the Messenger from the experimental data. We have shown that the optimal initial field parameters include setting the penetration of a partial interplanetary magnetic field into the magnetosphere with a penetration coefficient of 0.2.     

The Magnetic Field Pile-up and Density Depletion in the Martian Magnetosheath: A Comparison with the Plasma Depletion Layer Upstream of the Earth's Magnetopause

Using magnetometer and electron observations from the Mars Global Surveyor (MGS) and the Wind spacecraft we show that the region of magnetic field pile-up and density decrease located between the Martian ionosphere and bow shock exhibit strong similarities with the plasma depletion layer (PDL) observed upstream of the Earth's magnetopause in the absence of magnetic reconnection when the magnetopause is a solid obstacle in the solar wind. A PDL is formed upstream of the terrestrial magnetopause when the magnetic field piles up against the obstacle and particles in the pile-up region are squeezed away from the high magnetic pressure region along the field lines as the flux tubes convect toward the magnetopause. We here discuss the possibility that at least part of the region of magnetic field pile-up and density depletion upstream of Mars may be formed by the same physical processes which generate the PDL upstream of the Earth's magnetopause. More complete ion, electron, and neutral measurements are needed to conclusively determine the relative importance of the plasma depletion process versus exospheric processes.     

Telemetry Transmitters Using Solid-State Wideband Microwave Voltage-Controlled Oscillators

A practical approach for meeting the immediate and future needs of communication systems that require very wideband transmitters capable of operating in the S-, C-, and X-band frequency ranges is described. Included are: 1) a review of the basic studies conducted to determine the most practical transmitter approach for wideband applications; 2) a discussion of a prototype 10-watt frequency-modulated transmitter developed to demonstrate the feasibility of a wideband system; and 3) a review of the preliminary computer analyses and empirical results obtained on the development of a unit capable of wide deviation with reasonable linearity at baseband frequencies up to 10 Megahertz.