中国科学院机构知识库网格系统: 检索

浏览/检索结果: 共7条，第1-7条

帮助

条数/页：排序方式：
	In-orbit Demonstration of X-Ray Pulsar Navigation with the Insight-HXMT Satellite 期刊论文 OAI收割 The Astrophysical Journal Supplement Series, 2019, 卷号: 244, 页码: 1 作者: HXMT \| 收藏 \| 浏览/下载：14/0 \| 提交时间：2022/02/08 pulsars: general techniques: miscellaneous Astrophysics - Instrumentation and Methods for Astrophysics Abstract: In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT) Satellite, which was launched on 2017 June 15. The new pulsar navigation method Significance Enhancement of Pulse-profile with Orbit-dynamics is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from 2017 August 31 to September 5. Using the five-day long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard: High Energy X-ray Telescope, Medium Energy X-ray Telescope, and Low Energy X-ray Telescope, respectively. By combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3ҩ and 10 m s^-1 (3ҩ, respectively.
	Synthesis, characterization, and luminescent properties of a red-emitting Europium complex (EI CONFERENCE) 会议论文 OAI收割 1st International Conference on Energy and Environmental Protection, ICEEP 2012, June 23, 2012 - June 24, 2012, Hohhot, China 作者: Li B.; Zhang L.; Zhang L.; Li B.; Li B. 收藏 \| 浏览/下载：78/0 \| 提交时间：2013/03/25 a fluorine functionalized 1 10-phenanthroline ligand 3-ethyl-2-(2- fluorophenyl) imidazo[4 5-f]1 10-phenanthroline(EFPIP) and the corresponding red-emitting Eu(III) complex Eu(DBM)3(EFPIP) (DBM = dibenzoylmethanate) was synthesized and the photophysical properties and electroluminescent(EL) performances were researched. When Eu(DBM) 3(EFPIP) was used as emitting material in organic devices the maximum efficiency and luminance of red emission achieved from the EL device with the configuration of ITO/m-MTDATA (30 nm)/NPB (20 nm)/x wt% Eu(DBM) 3(EFPIP) doped in CBP (30 nm)/Bphen (20 nm)/Alq3 (20 nm)/LiF (0.8 nm)/Al were 3.6 cd/A and 563 cd/m2 respectively. Compared with the previously reported devices based on methyl or chlorine substitute Eu(III) complexes the EL performances of the device using Eu(DBM)3(EFPIP) as an emitter was significantly enhanced due to the introduction of fluorine. (2012) Trans Tech Publications Switzerland.
	Characteristics of ZnMgO-based metal-semiconductor-metal photodetectors (EI CONFERENCE) 会议论文 OAI收割 International Symposium on Photoelectronic Detection and Imaging, ISPDI 2007: Photoelectronic Imaging and Detection, September 9, 2007 - September 12, 2007, Beijing, China 作者: Zhang J.; Li B.; Li B.; Li B.; Zhao Y. 收藏 \| 浏览/下载：23/0 \| 提交时间：2013/03/25 In recent years ZnMgO semiconductor alloys with a direct bandgap tunable between 3.37 eV and 7.8 eV become one of the most suitable materials for the fabrication of ultraviolet detectors. In this paper we have fabricated metal-semiconductor-metal photodetectors on 1-m thick Zn 0.8Mg0.2O films. The interdigital metal electrodes are 500 m long and 5 m wide with an interelectrode spacing 2 m 5 m and 10 m respectively. Zn0.8Mg0.2O films were grown on quartz by ratio frequency magnetron sputtering at 500C. Dark current spectral responsivity and pulse response were carried out for the devices with different finger pitches. All the photodetectors showed the peak responsivity at 330 nm and the ultraviolet-visible rejection ratio (R330 nm/R400 nm) is more than four orders of magnitude at 3 V bias. For the device with 2 m finger pitch the detectivity was calculated as 4.21011 cm Hz 1/2/W at 330 nm. Furthermore the transient response measurement for all devices revealed similar rise time of 10 ns. The 90%-10% fall times are 130 ns 170 ns and 230 ns for the devices with different finger pitches of 2 m 5 m and 10 m respectively..
	Design of dual-FOV refractive/diffractive LWIR optical system (EI CONFERENCE) 会议论文 OAI收割 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Advanced Optical Manufacturing Technologies, July 8, 2007 - July 12, 2007, Chengdu, China 作者: Wang L.-J.; Zhang J.-P.; Wang L.-J.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：33/0 \| 提交时间：2013/03/25 An infrared-optical zoom system using binary element is proposed in this paper. The two main advantages of the zoom system introducing here are: bigger F-number and lower cost. The primary optical properties are: F/#=1 Second Others zoom ratio =1:4 binary element is used to correct the chromatical aberration by taking the advantage of negative dispersion characteristics and the cost of the system is lower than that of conventional ones with Zinc Selenide (Znse) material at the same level. In the binary element is rotational symmetric with one step which is easy to fabricate in order to balance 5th spherical aberration and dual field are 26.6 and 5.6respectively. Wider field of view is used for search and the smaller one is used for imaging details. This system uses un-cooled infrared detector with 320240 pixels and 45m pixel size. The F-number matches the sensitivity range of the detector array. Three aspects are considered during design process to make the system more satisfactory and more achievable. First 5th coma aberration and 5th astigmatic aberration the manner of zoom is accomplished by exchanging tow lenses into the smaller field of view system layout. The lens exchange manner faces the requirement of simple system structure and good image quality in both focal points. It can also make the system more feasible in the alignment process than mechanical-zooming manner and optical-zooming manner high-order asphere surfaces with 2th order to 10 th order are also hired in the system. Asphere surface is useful in compressing the system and improving optical system transmittance. This kind asphere surface is on industrial level featuring low cost and easy to fabricate. It is shown that good image quality can achieved by implementing five Germanium lenses and the transmittance of system is 72%. All aberrations are diffraction-limited both spherical aberration and astigmatic aberration are corrected. When the field of view(FOV) is 26.6 and the focal length is 152mm MTF at Nyquist frequency(11lp/mm) is great than 0.7. The spherical aberration is -0.0073. The coma aberration is 0.0978 and the astigmatic aberration is -0.013. When the field of view(FOV) is 5.6 and the focal length is 38mm MTF at Nyquist frequency is great than 0.8 with spherical aberration -0.0046 the coma aberration 0.055 and astigmatic aberration 0.034.
	A new spaceborne compression approach for remote sensing imagery (EI CONFERENCE) 会议论文 OAI收割 ICO20: Remote Sensing and Infrared Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China 作者: Xu S. 收藏 \| 浏览/下载：27/0 \| 提交时间：2013/03/25 After analyzing advantages and disadvantages of these typical encoding methods: SPIHT and VQ a "DWT+MRLE" approach for spaceborne data compression was proposed in this paper. This approach includes two steps: Discrete Wavelet Transform (DWT) and Modified Run Length Encoding (MRLE). The former used CDF9/7 biorthogonal wavelet filters to powerfully get rid of correlation between pixels in imagery. The later put enlightening information into the lowest bit of some key-position transform coefficients. Consequently CDF9/7 and MRLE together make hardware platform remain high real-time capability and help reconstructed images keep good fidelity with PSNR being about 40dB compared with the original ones. Comparison between experimentations on SPOT4's low-spatial-resolution (10m) imagery and Ikonos2's high-spatial-resolution (1m) imagery shows this "DWT+MRLE" method having better performance for remote-sensed imagery especially those of higher resolution. Although inferior to 8:1 Compression Ration (CR) here near 5:1 is greater than France SPOT5's 3:1 and American Ikonos2's 11:2.6 on-board data compression. More important this method having less computational amount is good for spaceborne capability of real time. The consumed time of different image size is also presented in this paper based on TI TMSC6416 DSP chip with 600MHz CPU cycle clock.
	Study of micro-actuator with electrostatic actuating (EI CONFERENCE) 会议论文 OAI收割 ICO20: MEMS, MOEMS, and NEMS, August 21, 2005 - August 26, 2005, Changchun, China 作者: Liu C.-X.; Liu C.-X. 收藏 \| 浏览/下载：17/0 \| 提交时间：2013/03/25 The micro-actuator with the torsion beam and the cantilever beam on silicon is designed and analyzed which is actuated by electrostatic force. Based on the torsion dynamics theory the technique and relative formula are presented for analyzing the actuating voltage and the switching time on which the effect of the air squeeze film damping is already considered. The optimized results of the structural parameters are compared between this technique and the finite element modeling (FEM). The optimized result of parameters is as: length width and thickness of the torsion beam are 700 12 and 10m length and width of the cantilever beam are 1900 and 1000m length and width of the balance beam are 100 and 1000m and distance of the upper and lower electrodes is 55m respectively. The actuating voltage is about 50 V and the switching time Toff and Ton are about 5 and 12 ms respectively. The computed results show that the air squeeze film damping is an important factor for the study of dynamic response on micro-actuator. Finally an optical technique is described for the measurement of the actuating voltage and switching time of the device and the difference between the experimental results and theoretical datum is discussed.
	Fabrication and electron emission of carbon microtubes (EI CONFERENCE) 会议论文 OAI收割 Technical Digest of the 18th International Vacuum Nanoelectronics Conference, IVNC 2005, July 10, 2005 - July 14, 2005, Oxford, United kingdom 作者: Liu L.; Liu L.; Wang W.; Wang W. 收藏 \| 浏览/下载：40/0 \| 提交时间：2013/03/25 Carbon nanotubes have been attracting attention because of their unique physical properties and their application potential for field emission cathode. Carbon nanotubes possess the following properties favorable for field emission material such as a high aspect ratio and sharp tip high chemical stability high mechanical strength stable at high temperature. Some research works on carbon nanotubes field emitter and field emission display have been reported. Here a kind of carbon microtubes and its field emission properties are introduced. They have some different properties with carbon nanotubes and the density is lower than carbon nanotubes bundles. These carbon microtubes are directly synthesized by liquidoid epitaxy method on silicon substrates at low temperature. The field emission properties of carbon microtubes are reported too. Carbon microtubes film is synthesized in liquid by electrolysis. The graphite plate is as anode and n-silicon substrate with resistivity of 4-8 cm is as cathode. The electrolysis current is about 5-8mA/cm2 and applied voltage is 800-1500V. Temperatures of the methanol base solution is maintained at 60C in process of deposition of carbon microtubes. Carbon microtubes film is observed by scanning electron microscopy(SEM) as shown in fig.1(a b). The wall's thickness of carbon microtube is about 60nm. The diameter of carbon microtube is about 0.8 m. Raman spectrum of carbon microtubes film shows the two peaks at 1342and 1560cm-1. The field emission properties of carbon microtubes are measured in high vacuum chamber(10-5Pa). The emission area of carbon microtubes is 0.5cm 0.5cm. The threshold of field emission of the carbon microtubes film is about 3.6V/ m. Field emission property of carbon microtubes film is shown in fig.2. Another when the electric field between anode and cathode is 10V/ m the electric field distribution on single carbon microtube is also given after calculation according to electric field theory. Fig 3 shows that electric field distribution vertical section on the of single carbon microtube top with 2 m of highness. These results may help us to understand field emission properties of carbon microtubes. According to research results it is found that liquidoid synthesis is simple method to produce carbon microtubes cold cathode material and the carbon microtubes have better field emission properties. 2005 IEEE.