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排序方式: 共有502条查询结果,搜索用时 15 毫秒
81.
SHOU Ji-lin YUAN Ying Dept. of Applied Mathematics Xi′an Jiaotong University Xi′an China 《系统科学与系统工程学报(英文版)》1999,(4)
1 IntroductionWilliamA.ByrdhasstudiedtheexistenceofequilibriuminasimplemodelwithdistinctiveChineseeconomy(seeByrd,1989).Industrialgoodsaresubjecttomultipleallocationmechanism,includingvariousadministrativechannels,termedplanningsystemandcom-modityma... 相似文献
82.
Huiling Zhang Min Hao Hao Wu Hing-Fung Ting Yihong Tang Wenhui Xi Yanjie Wei 《清华大学学报》2022,(5):843-854
Sequence-based protein tertiary structure prediction is of fundamental importance because the function of a protein ultimately depends on its 3 D structure.An accurate residue-residue contact map is one of the essential elements for current ab initio prediction protocols of 3 D structure prediction.Recently,with the combination of deep learning and direct coupling techniques,the performance of residue contact prediction has achieved significant progress.However,a considerable number of current D... 相似文献
83.
Lijie Zhang Jianguo Huang Yong Jin Yunshan Hou Min Jiang Qunfei Zhang .College of Marine Northwestern Polytechnical University Xi’an P.R.China .Yichang Testing Technique Research Institute Yichang 《系统工程与电子技术(英文版)》2010,21(2):186-190
A new monostatic army system taking advantage of diverse waveforms to improve the performance of underwater target localization is proposed.Unlike the coherent signals between different elements in common active array,the transmitted signals from different elements here are spatially orthogonal waveforms which allow for array processing in the transit mode and result in an extension of array aperture.The mathematical derivation of Capon estimator for this sonar system is described in detail.And the performance of this orthogonal-waveform based sonar is analyzed and compared with that of its phased-array counterpart by water tank experiments.Experimental results show that this sonar system could achieve 12 dB-15 dB additional array gain over its phased-array counterpart,which means a doubling of maximum detection range.Moreover,the angular resolution is significantly improved at lower SNR. 相似文献
84.
85.
ZHANG Xi LIU Hui JIANG Kunliang WANG Jinqi XIONG Zhuanxian HE Lingxiang Lü Baolong 《武汉大学学报:自然科学英文版》2018,23(1):51-55
We report laser frequency stabilization with modulation transfer spectroscopy (MTS) on 85Rb atoms. With both PZT (piezo-electric transducer) slow-loop feedback and current fastloop feedback to the laser head, we get a linewidth narrowing less than 5 kHz simultaneously. Laser injection to a laser diode and frequency beating with another polarization spectroscopy based stabilization setup are also employed to check the narrow linewidth property. With the help of the technique, a linewidth around kHz-level laser is obtained and pave the way for the locking of the lattice laser of ytterbium clock with transfer cavity technique. The setup can be used as a frequency reference for precise frequency control of atomic clock system. 相似文献
86.
Hierarchical porous metal oxides arrays is critical for development of advanced energy storage devices. Herein, we report a facile template-assisted electro-deposition plus glucose decomposition method for synthesis of multilayer CoO/C hollow spheres arrays. The CoO/C arrays consist of multilayer interconnected hollow composite spheres with diameters of ~350 nm as well as thin walls of ~20 nm. Hierarchical hollow spheres architecture with 3D porous networks are achieved. As cathode of high-rate hybrid batteries, the multilayer CoO/C hollow sphere arrays exhibit impressive enhanced performances with a high capacity (73.5 mAh g?1 at 2 A g?1), and stable high-rate cycling life (70 mAh g?1 after 12,500 cycles at 2 A g?1). The improved electrochemical performance is owing to the composite hollow-sphere architecture with high contact area between the active materials and electrolyte as well as fast ion/electron transportation path. 相似文献
87.
Characteristics of dry friction backward whirl-A self-excited oscillation in rotor-to-stator contact systems
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JIANG Jun SHANG ZhiYong & HONG Ling MOE Key Laboratory of Strength Vibration Xi’an Jiaotong University Xi’an China 《中国科学:技术科学》2010,(2)
In this paper, the response characteristics of dry friction backward whirl of a general rotor/stator model, which accounts for both the dynamics of the rotor and the stator as well as the friction and the deformation at the contact surfaces, are investigated. The existence boundaries and the whirl frequencies of the dry friction backward whirl are determined analytically. It is found that there are two or three existence boundaries of the dry friction backward whirl that usually form two existence regions, ... 相似文献
88.
GUO Jie CHEN HuiJuan SUN WeiGuo HAO RuiTing XU YingQiang & NIU ZhiChuan Material School NorthWest Polytechnical University Xi’an China Luoyang Optical Electronics Center Luoyang Institute of Semiconductors Chinese Academy of Sciences Beijing 《中国科学:技术科学》2010,(4)
Type Ⅱ superlattices(SLs) short period InAs(4ML)/GaSb(8ML) were grown by molecular-beam epitaxy on lattice-mismatched GaAs substrates and on GaSb substrates.A smooth GaSb epilayer was formed on GaAs substrates by inserting mulit-buffer layers including an interfacial misfit mode AlSb quantum dot layer and AlSb/GaSb superlattices smooth layer.SLs grown on GaAs substrates(GaAs-based SLs) showed well-resolved satellite peaks in XRD.GaSb-based SLs with better structural quality and smoother surface showed strong photoluminescence at 2.55μm with a full width at half maximum(FWHM) of 20 meV,narrower than 31 meV of GaAs-based SLs.Inferior optical absorption of GaAs-based SL was observed in the range of 2-3μm. Photoresponse of GaSb-based SLs showed the cut-off wavelength at 2.6μm. 相似文献
89.
90.
XIAO Yang DU Xi |yu Rolf Unbehauen .Institute of Information Science Northern Jiaotong University Beijing P.R.China . Institute of General Theoretic Electronic |Technique University of Erlangen |Nürnberg Cauerstr. 《系统科学与系统工程学报(英文版)》1999,(3)
1 IntroductionThereexistsakindof2Ddiscretesystemswithuncertainparametersorsubjecttorandomdisturbances.Differentfromuncertain1Dpolynomials,theparameterspaceoftheuncertain2Dpolynomialsisof(M+1)×(N+1)dimensionsatmost.ThoughsomeresultsabouttherobustH… 相似文献