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Ou X.,Fudan University | Ou X.,Beijing Institute of Spacecraft Environment Engineering | Wang H.,Fudan University | Fan F.,Fudan University | And 2 more authors.
Physical Review Letters | Year: 2015

Large magnetic anisotropy energy (MAE) is desirable and critical for nanoscale magnetic devices. Here, using ligand-field level diagrams and density functional calculations, we well explain the very recent discovery [I. G. Rau et al., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001) surface has a large MAE of more than 60 meV. More importantly, we predict that a giant MAE up to 110 meV could be realized for Ru adatoms on MgO (001), and even more for the Os adatoms (208 meV). This is a joint effect of the special ligand field, orbital multiplet, and significant spin-orbit interaction, in the intermediate-spin state of the Ru or Os adatoms on top of the surface oxygens. The giant MAE could provide a route to atomic scale memory. © 2015 American Physical Society.


Li G.,Dalian Jiaotong University | Liu X.,Harbin Power System Engineering and Research Institute | Li T.,Beijing Institute of Spacecraft Environment Engineering
Composites Part B: Engineering | Year: 2013

Precise prediction on atomic oxygen undercutting by numerical simulation technique plays an importance role for long lifetime spacecraft design. A Monte Carlo mathematical model is presented to predict the undercutting process interaction between atomic oxygen and polyimide films of spacecraft in low earth orbital degree. In the meantime, the physical undercutting processes is described by tracing transportation particle approach on the basis of statistics. Simulated results showed that undercutting profiles with breaker patterns are in good agreement with flight experimental data for 43° and 28.5° orbit angle, as well as complicated effect factors are discussed in detail. Larger atomic oxygen fluence is favorable for producing more depth and width undercutting profiles and maximum depth is always larger than maximum width. Mass loss increased with the initial impact reaction probability increasing and decreased with the thermal assimilation coefficient going down. Especially for bigger orbit angle, the difference between depth and width are reduced due to the decrement of depth and the increment of width. © 2012 Published by Elsevier Ltd.


News Article | September 28, 2016
Site: www.materialstoday.com

A nitrogen-doped mesoporous carbon thin film acts as a high capacity, binder-free supercapacitor with a long cycling stability, according to research published in the journal Applied Materials Today. [P Hu et al., Appl. Mater. Today (2016) 5, 1-8; DOI: 10.1016/j.apmt.2016.08.001] Pan Hu and Xinsheng Peng of Zhejiang University, in Hangzhou and Donghui Meng, Guohua Ren, Rongxin Yan of Beijing Institute of Spacecraft Environment Engineering, China, explain how they could convert gelatin/copper hydroxide nanostrands into a composite film of gelatin/HKUST-1, which they could then carbonize to generate the free-standing composite films. These films have a high specific energy of 28.1 Watt hours per kilogram and a specific capacity of 316 Farads per gram at a current density of 0.5 Amps per gram. They also have a capacitance retention of almost 93% and degrade by a mere 0.00064% after 11000 charge-discharge cycles, the team reports. Porous carbons, with their high surface area to volume ratio have been the focus of much research for their potential applications in electronics, separation science and beyond. They can be generated by chemical vapour decomposition, laser ablation, chemical or physical activation, carbonization of polymer aerogels, carbide-derived carbon, as well as template procedures. Often, their production then requires an additional step to dope them with nitrogen. Simpler approaches to functional porous carbons, for development as electrodes or supercapacitors are keenly sought and as such Hu and colleagues have sidestepped the problem of low doping levels seen with earlier approaches. Instead of using post-treatment with ammonia gas, the team has demonstrated how starting with a nitrogen-rich carbon compound and the carbonizing the processed material gives them much higher nitrogen content and so potentially more powerful electrical phenomena in the resulting doped material. They previously suggested gelatin as a low-cost, abundant fibrous material having a high nitrogen content, by virtue of it being a protein, as a precursor for a doped mesoporous carbon. Early studies required harsh conditions to generate the mesoporous material, but this leads to powders that then require a non-electrochemical binder to hold the particles together in a solid block before use. The presence of the binder inhibits activity, so a binder-free approach would be better. The team's room temperature method generates active thin films rather than powders and so requires no binder to aggregate particles into a usable component for their supercapacitor. The team concedes that their thin films are no more electrochemically active than other carbon-based materials, it is their method that sets apart the products and opens the door to a cool and efficient fabrication of supercapacitor films. David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".


Liu Y.,Dalian Maritime University | Li G.-H.,Dalian Jiaotong University | Jiang L.-X.,Beijing Institute of Spacecraft Environment Engineering
Acta Astronautica | Year: 2010

An Euler-Euler two-fluid model incorporating with the influence of gravity to describe the hydrodynamic behavior of dense gas-particle flows in gas-fluidization reactor is presented and simulated numerically. It based on the dense gases of kinetic theory and the kinetic theory of granular media for considering the interactions between particleparticle and gas-particles. Gas turbulent flow is solved by large eddy simulation. Results showed that the mean value and the variance of vertical particle velocity are greater than those of horizontal velocity under both lunar-reduced and earth gravity conditions. Comparison of the earth gravity, reduced condition is easier to produce the bigger volume bubble and the more heterogeneous flow structure, as well as the greater the variance of vertical and horizontal particle velocity and the higher particle fluctuation intensity. © 2010 Elsevier Ltd. All rights reserved.


Yan R.,Beijing Institute of Spacecraft Environment Engineering
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2015

The gas transport, viathe fairly long sampling pipeline in its partial pressure measurement, was empirically approximated, mathematically modeled on the basis of the previous studies on adsorption of unsteady-state gas, and analytically calculated and experimentally evaluated. The impact of the transport conditions, including but not limited to the pipeline length, position and pressure at the pipeline inlet, pressure and pumping speed of the analysis chamber, gas properties, stabilization and analysis times, on the partial pressure measurement was theoretically investigated. The gas transportation equation and pumping equation in the analysis chamber were formulated with the appropriate initial and boundary conditions, so the transient gas partial pressure distribution could be obtained. The spacecraft gas propellants were exemplified to test the calculated results. The experimental and calculated results were found to be in good agreement. ©, 2015, Science Press. All right reserved.


Gong Z.,Beijing Institute of Spacecraft Environment Engineering
Proceedings of the International Astronautical Congress, IAC | Year: 2015

Laser-driven flyer technique (LDFT) shows many advantages in simulating micro-space debris hypervelocity impacting effects. In this paper; some recent progresses in laser-driven flyer system for space debris hypervelocity impact simulations researches conducted in CAST were reviewed and introduced, including: 1) Theoretical analysis of flyer velocity is conducted based on Lawrence Model; 2) A new kind of velocity in-situ measurement technology is developed for laser-driven flyer system;3) Flyers were accelerated up to 9 knVs with good repeatability using two layers targets; 4) Hypervelocity impact experiments of micro-space debris on spacecraft surface materials were carried out, and the degradation laws of material functional performance were obtained; 5) Cumulative damage evaluation method is studied; 6) Diamond-like Carbon (DLC) film is employed to protect the optical materials against micro-spacc debris impact. At last, the new trend of laser-driven flyer hypervelocity impact research is addressed. Copyright © (2015) by International Astronautical Federation All rights reserved.


Patent
Beijing Institute of Spacecraft Environment Engineering | Date: 2015-04-01

A fuel-free spacecraft propelling system having an open-ended outer cylinder of a propelling device and an atomic oxygen collecting device is disclosed. The latter is arranged at the forwardly-propelled front end of the outer cylinder and is hermetically connected with an RF generating device and an ion cyclotron wave heating device through a magnetic confinement device. A spiral wave discharge oxygen plasma inlet and a spiral wave discharge oxygen plasma outlet in the ion cyclotron wave heating device are respectively provided with another magnetic confinement device. The propulsion of the invention does not need to carry the propellant, which greatly reduces the launch costs, enables a spacecraft to work on an orbit in the whole life circle work and is advantageous.


Patent
Beijing Institute of Spacecraft Environment Engineering | Date: 2013-05-07

A chemical-electromagnetic hybrid propeller with variable specific impulse. Fuel gas ejected out from a spraying tube of the chemical propeller through chemical propulsion enters an ionization chamber through a first magnetic mirror tube for ionization. The fuel gas after ionization is heated up by radio-frequency ion cyclotron waves in an ion cyclotron wave heating chamber so as to improve the kinetic energy. Then a second magnetic mirror tube is used, so that ions in the fuel gas after the ionization are heated up many times in a reciprocating manner between the magnetic mirror tubes, and ejected to generate forward propulsion force. By means of the propeller, the propulsion force and the specific impulse are greatly increased.


Patent
Beijing Institute of Spacecraft Environment Engineering | Date: 2013-05-07

A fuel-free spacecraft propelling system having an open-ended outer cylinder of a propelling device and an atomic oxygen collecting device is disclosed. The latter is arranged at the forwardly-propelled front end of the outer cylinder and is hermetically connected with an RF generating device and an ion cyclotron wave heating device through a magnetic confinement device. A spiral wave discharge oxygen plasma inlet and a spiral wave discharge oxygen plasma outlet in the ion cyclotron wave heating device are respectively provided with another magnetic confinement device. The propulsion of the invention does not need to carry the propellant, which greatly reduces the launch costs, and enables a spacecraft to advantageously have an increased orbit life over existing spacecraft systems.


Patent
Beijing Institute of Spacecraft Environment Engineering | Date: 2015-04-01

A chemical -electromagnetic hybrid propeller with variable specific impulse. Fuel gas ejected out from a spraying tube of the chemical propeller through chemical propulsion enters an ionization chamber through a first magnetic mirror tube for ionization. The fuel gas after ionization is heated up by radio-frequency ion cyclotron waves in an ion cyclotron wave heating chamber so as to improve the kinetic energy. Then a second magnetic mirror tube is used, so that ions in the fuel gas after the ionization are heated up many times in a reciprocating manner between the magnetic mirror tubes, and ejected to generate forward propulsion force. By means of the propeller, the propulsion force and the specific impulse are greatly increased.

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