检索结果-南通市图书馆

Closed-loop flow control of an ultra-compact serpentine inlet based on nondimensional model

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第10期33卷 2555-2562页

作者： Xingya da Jianchao FAN High Speed Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

Ultra-compact serpentine inlet faces serve inlet-engine compatibility issues due to flow *** ensure inlet-engine compatibility over a wide range of Mach number,novel active flow control techniques with the ability of being opened or adjusted as needed draw many attentions in recent *** this paper,a feedback control system was developed based on the method of microjet *** proposed system includes a pressure adjusting valve to adjust the control effort,a dynamic pressure sensor to sense the inlet distortion intensity,a signal processing instrument to calculate the Root-Mean-Squared(RMS)pressure,and a controller to implement feedback *** achieve high quality closed-loop controls at dynamic conditions,a novel nondimensional feedback method was *** advantage of this nondimensional method was validated at both off-design and arbitrarily changing Mach number *** a sectional PI control law,the RMS control error reduced more than 56%at arbitrary changing *** in this paper also showed that the dynamics of this nondimensional system can be simplified as a stable second-order overdamped system.

关键词： Closed-loop flow control Flow distortion Nondimensional feedback PI control Serpentine inlet

Impact of China’s Outward Foreign Direct Investment on Enterprise Performance

在线全文

学校读者我要写书评

暂无评论

Journal of Donghua University(English Edition) 2019年第5期36卷 513-520页

作者： XU Qiqi WANG Lei id Bouichou Said Glorious Sun School of Business and Management Donghua University

The present study seeks to address two fundamental questions.(1)Does outward foreign direct investment(OFDI)enhance enterprise performance ultimately?(2)How does this effect come about?A new dataset from the years 2011 to 2016 based on the micro-data of 88 Chinese multinational-listed enterprises was used to test research hypotheses with the mediating effect modeling *** study results reveal that:(1)the investment intensity has a positive influence,while investment span has a negative influence on enterprise performance;(2)the enhanced innovation capability can considerably increase the enterprise performance,while investment intensity and span both hinder the upgrading of innovation capability;and(3)the innovation capability of an enterprise plays a partial intermediary role among investment span and enterprise ***,there is no mediating effect between investment intensity,innovation ability,and enterprise performance.

关键词： outward foreign direct investment(OFDI) enterprise performance innovation capability mediating effect

Torsion Fields Generated by the Quantum Effects of Macro-bodies

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第12期22卷 335-343页

作者： da-Ming Chen National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

We generalize Einstein's General Relativity(GR)by assuming that all matter(including macro-objects)has quantum *** appropriate theory to fulfill this task is Gauge Theory Gravity(GTG)developed by the Cambridge *** is a“spin-torsion”theory,according to which,gravitational effects are described by a pair of gauge fields defined over a flat Minkowski background *** matter content is completely described by the Dirac spinor field,and the quantum effects of matter are identified as the spin tensor derived from the spinor *** existence of the spin of matter results in the torsion field defined over *** field plays the role of Bohmian quantum potential which turns out to be a kind of repulsive force as opposed to the gravitational potential which is *** equivalence principle remains and essential in this theory so that GR is relegated to a locally approximate theory wherein the quantum effects(torsion)are *** a toy model,we assume that the macro matter content can be described by the covariant Dirac equation and apply this theory to the simplest radially symmetric and static gravitational ***,by virtue of the cosmological principle,we are led to a static universe model in which the Hubble redshifts arise from the torsion fields.

关键词： cosmology:theory (cosmology:)dark matter (cosmology:)dark energy

Strong Approximation for a Toric Variety

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2021年第1期37卷 95-103页

作者： da Sheng WEI Academy of Mathematics and System Science CASBeijing 100190P.R.China School of Mathematical Sciences University of CASBeijing 100049P.R.China

Let X be a toric variety over a number field k with k[X]×=k×.Let W■X be a closed subset of codimension at least *** prove that X\W satisfies strong approximation with algebraic Brauer-Manin obstruction.

关键词： Torus universal torsor strong approximation Brauer–Manin obstruction

The Dynamics of Vector Fields with Singularities

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2022年第1期38卷 225-248页

作者： da Wei YANG School of Mathematical Sciences Soochow UniversitySuzhou 215006P.R.China

We give a brief survey on the dynamics of vector fields with *** aim of this survey is not to list all results in this field,but only to introduce some results from several viewpoints and some technics.

关键词： Vector filed singularity Morse–Smale horseshoe singular hyperbolicty

Van Hove Scenario in Two-Layer BCS Model

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1996年第1期13卷 46-49页

作者： SHI da-ning College of Science Nanjing University of Aeronautics and AstronauticsNanjing 210016

In this letter,we study the effects of the interlayer hopping and pairing of the layered high-T_(c) superconductors within tiie framework of BCS-van Hove singularity *** obtained results are in qualitative agreement w... 详细信息

关键词： Hove singularity qualitative

Depth to the bottom of magnetic layer in South America and its relationship to Curie isotherm,Moho depth and seismicity behavior

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2018年第1期9卷 93-107页

作者： Javier idárraga-García Carlos A.Vargas Research Group on Geophysics Universidad Nacional de ColombiaBogotáColombia Deportment of Geosciences.Universidad Nacional de Colombia.Bogota.Colombia

We have estimated the DBML（depth to the bottom of the magnetic layer） in South America from the inversion of magnetic anomaly data extracted from the EMAG2 grid. The results show that the DBML values, interpreted as the Curie isotherm, vary between -10 and -60 km. The deepest values（〉-45） are mainly observed forming two anomalous zones in the central part of the Andes Cordillera. To the east of the Andes, in most of the stable cratonic area of South America, intermediate values（between -25 and-45 km） are predominant. The shallowest values（〈-25 km） are present in northwestern corner of South America, southern Patagonia, and in a few sectors to the east of the Andes Cordillera. Based on these results, we estimated the heat flow variations along the study area and found a very good correlation with the DBML. Also striking is the observation that the thermal anomalies of low heat flow are closely related to segments of flat subduction, where the presence of a cold and thick subducting oceanic slab beneath the continent, with a virtual absence of hot mantle wedge, leads to a decrease in the heat transfer from the deeper parts of the *** comparing our results with the Moho depths reported by other authors, we have found that the Curie isotherm is deeper than Moho in most of the South American Platform（northward to -20°S）, which is located in the stable cratonic area at the east of the Andes. This is evidence that the lithospheric mantle here is magnetic and contributes to the long wavelength magnetic signal. Also, our results support the hypothesis that the Curie isotherm may be acting as a boundary above which most of the crustal seismicity is concentrated. Below this boundary the occurrence of seismic events decreases dramatically.

关键词： Magnetic layer depth Curie isotherm Heat flow Crustal seismicity Flat subduction South America

Tailoring interface of lead-halide perovskite solar cells

在线全文

学校读者我要写书评

暂无评论

Nano Research 2017年第5期10卷 1471-1497页

作者： Peimei da Gengfeng Zheng Laboratory of Advanced Materials Department of Chemistry Collaborative Innovation Center of Chemistry for Energy Materials Fudan University Shanghai 200438 China

Lead-halide perovskite solar cells （PSCs） have attracted tremendous attention during the past few years owing to their extraordinary electronic and photonic properties. To improve the performances of PSCs, many researchers have focused on the compositional engineering, solvent engineering, and film fabrication methodologies. Interfacial engineering of PSCs has become a burgeoning field in which researchers aim to deeply understand the mechanisms of cells and thereby increase the efficiency and stability of PSCs. This review focuses on the interface tailoring of lead-halide PSCs, including the modification of each layer of the cell structure （i.e., perovskite absorber, electron-transport layers, and hole- transport layers） and the interfacial materials that can be introduced into the PSCs.

关键词： perovskite solar cell interface engineering

Mean-square exponential stability for stochastic time-varying delay systems with Markovian jumping parameters:a delay decomposition approach

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2011年第5期22卷 816-824页

作者： Li Ma Feipeng da Key Laboratory of Measurement and Control for Complex Systems of Engineering Ministry of Education Research Institute of Automation Southeast University Nanjing 210096 E R. China College of Electronic and Information Engineering Jiangsu University Zhenjiang 212013 P. R. China

The mean-square exponential stability problem is investigated for a class of stochastic time-varying delay systems with Markovian jumping parameters. By decomposing the delay interval into multiple equidistant subintervals, a new delay-dependent and decay-rate-dependent criterion is presented based on constructing a novel Lyapunov functional and employing stochastic analysis technique. Besides, the decay rate has no conventional constraint and can be selected according to different practical conditions. Finally, two numerical examples are provided to show that the obtained result has less conservatism than some existing ones in the literature.

关键词： stochastic systems time-varying delay Markov chain linear matrix inequality (LMI).