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News Article | April 16, 2017
Site: news.yahoo.com

China launched its newest communications satellite, Shijian-13, on Wednesday. Other than a throughput capacity that exceeds all of the country’s earlier communications satellites taken together, Shijian-13 was another first for the Asian powerhouse: it is propelled by an ion thruster, which coverts solar energy into fuel. The ion thruster was indigenously developed by Chinese researchers, who spent about five years on it, Chinese daily Global Times reported. The thruster reduces the amount of jet propellant needed to be carried by the spacecraft for it to carry out maneuvers in space, potentially improving efficiency by up to a factor of 10, according to engineers from the Lanzhou Institute of Physics, which built the thruster. The country has a very ambitious space program, including building its own space station and landing on the crewed mission to the moon, and earlier in the year, it declared a November mission that would return samples from the moon. Closer in time, the launch of the country’s first cargo spacecraft is currently scheduled for April 20. Tianzhou-1 is the first cargo vessel independently built by China, and can carry a payload of up to six tons. There is one capsule each for carrying the cargo and the propellant, and the spacecraft will weigh about 13 tons at liftoff. It has been designed to stay in space for up to three months. The launch of Tianzhou-1 — to take place from facility at Wenchang, China, using an indigenous Long March 7 rocket — will also showcase China’s capability to resupply and refuel the Tiangong-2 space laboratory, which was launched in September 2015. Along with Tiangong-1 and other components to be launched by 2022, the space lab would have formed Tiangong-3, China’s own orbiting space station. But those plans seem to be up in the air after Tiangong-1 malfunctioned; it is expected to fall to Earth this year, but the time and place it will fall are not known. Despite the Tiangong (which means heavenly palace) setback, the country has made big strides in its space program. The first Chinese astronaut went beyond the atmosphere only in 2003, but it has already landed a rover, Jade Rabbit, on the moon — one of the only three countries to do so — in 2013. The rover, however, developed problems soon after. Two astronauts also spent a month aboard Tiangong-2 in 2016.

He M.,Beijing Institute of Technology | Guo D.,Beijing Institute of Technology | Feng Y.,Lanzhou Institute of Physics | Xiong X.,China Institute of Metrology | And 3 more authors.
Journal of Mass Spectrometry | Year: 2015

In this study, three ion-neutral collisionmodels have been discussed and compared, including the Langevin, the hard-sphere and the mixed collision models. With the pseudo-potential approximation, analytical expressions of ion secular motions with the hardsphere and mixed collision models have been obtained for the first time. Through numerical simulations and theoretical calculations, it is found that the mixed collision model could be used as a general description of ion-neutral collisions under different conditions. Langevin collision model is a good description of low energy collisions between small ions and neutrals, while hard-sphere collision model could be used to describe high energy collisions and/or ions with higher masses (larger physical sizes). These analytical expressions of ion motion decay profiles enable the creation of direct relationships between time-domain image currents with ion collision cross sections. Copyright © 2015 John Wiley & Sons, Ltd.

Ma D.,Lanzhou Institute of Physics
Advanced Materials Research | Year: 2012

We reviewed an introductory course in embedded systems, it is not in the embedded system resource constraints, but depends on the interaction between the physical world. This course teaches students the basic model, and analysis tools, design in embedded systems use. The traditional undergraduate courses in embedded systems focus on AD hoc of engineering practice, the use of existing modeling technology, often omitted critical analysis and meta-modeling; We emphasize cyber-physical design model and the embedded system. Students will learn how to model the physical world differential equation and continuous time, and how to use logic model calculation model and discrete state machine. Officially designated verification technologies, want to act. Structure design project for the laboratory and conception is applied in the design of the embedded system and cyber-physical to provide real-time, parallel behavior. © (2012) Trans Tech Publications, Switzerland.

Zhang T.,Lanzhou Institute of Physics
Proceedings of the International Astronautical Congress, IAC | Year: 2013

LIPS-200 ion electric propulsion system has been developed by Lanzhou institute of physics (LIP) since 1990s and its first flight test was conducted on SJ-9A satellite launched on October 10, 2012. After the checkout and activation in orbit were finished, the first firing operation has been implemented successfully on November 7, 2012. The first-phase test plan was completed until December 9, 2012, and the second-phase test plan was implemented continuously. In this paper, the initial test results of the LIPS-200 on SJ-9A satellite in the first phase are presented in details. Copyright ©2013 by the International Astronautical Federation.

Tianping Z.,Lanzhou Institute of Physics
Proceedings of the International Astronautical Congress, IAC | Year: 2013

LIPS-200 ion electric propulsion system for the NSSK mission on DFH-3B satellite platform has been developing by Lanzhou Institute of Physics since 2010. The LIPS-200 system is composed of a system control unit, 4 ion thrusters, 2 power processing units(PPU), and a xenon storage and feed subsystem including 2 xenon tanks, a pressure regulator unit and 4 flow controllers. In this paper, the development status of the LIPS-200 ion electric propulsion system is summarized and the next development program is presented. Copyright © 2013 by the International Astronautical Federation. All rights reserved.

Yue H.,Dalian University of Technology | Wu A.,Dalian University of Technology | Feng Y.,Lanzhou Institute of Physics | Zhang X.,Dalian University of Technology | Li T.,Dalian University of Technology
Thin Solid Films | Year: 2011

Al-doped ZnO thin films were deposited by radio frequency magnetron sputtering using a ZnO target with 2 wt.% Al2O3. The structures and properties of the films were characterized by the thin film X-ray diffraction, high resolution transmission electron microscopy, Hall system and ultraviolet/visible/near-infrared spectrophotometer. The Al-doped ZnO film with high crystalline quality and good properties was obtained at the sputtering power of 100 W, working pressure of 0.3 Pa and substrate temperature of 250 °C. The results of further structure analysis show that the interplanar spacings d are enlarged in other directions besides the direction perpendicular to the substrate. Apart from the film stress, the doping concentration and the doping site of Al play an important role in the variation of lattice parameters. When the doping concentration of Al is more than 1.5 wt.%, part of Al atoms are incorporated in the interstitial site, which leads to the increase of lattice parameters. This viewpoint is also proved by the first principle calculations. © 2011 Elsevier B.V. All rights reserved.

Xue D.-T.,Lanzhou Institute of Physics
Yuhang Xuebao/Journal of Astronautics | Year: 2011

The electrostatically suspended accelerometers are one of the main payloads in the gravity field measurement satellite. The accelerometer sensor heads (flight model) must be calibrated on-ground with gravity inclination before and after environmental test. As different coupling mechanism between sensitive axes from the conventional accelerometers, the model equation used during calibrating the accelerometers is differential. As the misalignment angles are extremely bigger than the gravitational tilt angle on-ground in the accelerometer range, the parameters each of the model equation could not be verified by using the conventional static calibration methods. For approximately estimating the scale factor and verifying consistency of the model equation parameters each of the twin accelerometers with the dynamic calibration method and obtaining the second order non-linearity coefficient with the electrical analogue method on the dedicated pendulum bench, one must adopt some technical artifices to make the third order non-linearity coefficient ignored. The techniques for preventing the spectrum leakage and depressing the magnitude of noise disturbance in the amplitude spectrum are put forward. The concrete executive plan and the effect of the electrical analogue method are unfurled by demonstration.

Xue D.-T.,Lanzhou Institute of Physics
Yuhang Xuebao/Journal of Astronautics | Year: 2011

In this paper, the specification items of the accelerometers are reduced to five kinds, of which the relation to the requirements is explained. It is accentuated that the sample rate of 10 SPS and the corresponding 3Hz bandwidth of the closed loop transfer function are indispensable. It is pointed out that the laboratory calibration shall be disturbed by the ambient vibration noise, so usual calibration methods are not applicable without exception, and main difficulty of the static calibration is accurately determining misalignment angles; the scale factors could be approximately estimated and the consistency of various parameters of the model equation for the twain accelerometers could be observed through the dynamic calibration with a dedicated pendulum bench; in order to implement various performance tests for accelerometers in the dedicated pendulum bench, the proof mass of the accelerometer is required to be levitated under the ground gravity; the function of the free fall test is limited and the test is not quantitative assessment test for the performance index of accelerometers; the analytic confirmation method is adopted to verify the noise of accelerometers before launch, and in order to reduce the noise, one must depend on the exhaustive theoretic analysis and experimental validation, find out the various influence factors and degrees one by one, take forceful means and faithfully improve the insufficiencies.

Wang J.-J.,Northwest Normal University | Wang D.-S.,Lanzhou Institute of Physics | Wang J.,Northwest Normal University | Zhao W.-L.,Northwest Normal University | And 2 more authors.
Surface and Coatings Technology | Year: 2011

In order to obtain the TiO2 films with high transmittance and superhydrophilicity without UV irradiation, porous TiO2/SiO2 bi-layer films were prepared by spin coated SiO2 sol and TiO2 sol including polyethylene glycol 2000 (PEG 2000) onto glass and subsequent calcination at 550°C. Meanwhile, factors that affect the TiO2/SiO2 bi-layer films transmittance and superhydrophilicity were investigated in details by observing their surface morphologies and measuring their water contact angles (WCAs), spreading time and transmittances. The results indicated that the as-prepared TiO2/SiO2 bi-layer film showed superhydrophilicity without UV irradiation when 0.5wt.% PEG 2000 was added in TiO2 sol. At the same time, its maximum transmittance was as high as 92.3%. The spreading time was only about 0.16s. More importantly, the resultant film had an excellent stability of the superhydrophilic property. © 2010 Elsevier B.V.

Wang J.,Northwest Normal University | Li Y.,Northwest Normal University | Wang D.-S.,Lanzhou Institute of Physics | Wang C.-W.,Northwest Normal University | Wang C.-W.,Lanzhou Institute of Physics
Thin Solid Films | Year: 2012

The super low refractive index of less than 1 is obtained through adjusting the deposition time of nano-metal Ag in Ag-anodic aluminum oxide (Ag-AAO) composite films. It is very interesting that the Ag-AAO composite films with super low refractive index are still transparent. Based on the results, the Ag-AAO composite films and titanium dioxide (TiO 2) films were used to assemble 1D TiO 2/Ag-AAO photonic crystal (PC) structure and its optical responses were simulated in the 500-2500 nm range by using the finite difference time domain method. It is found that the increase of Ag-AAO layer thickness makes the photonic band gap (PBG) become broad greatly, but has few effects on the blue edge of the PBG, which is different from the effect of TiO 2 layers. It is more important that a broad omnidirectional PBG can be easily obtained from the simple 1D TiO 2/Ag-AAO photonic crystal structure through the modulation of both the TiO 2 and Ag-AAO layer thicknesses. Furthermore, the absorption of 1D TiO 2/Ag-AAO PC structure at the PBG edges is very strong due to the photon localization in Ag-AAO layer. The different roles of Ag-AAO layer in the above mentioned 1D PC structure are mainly attributed to the different transmission process of optical pulse in Ag-AAO layer. © 2012 Elsevier B.V.

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