检索结果-南通市图书馆

Attractors for discrete Nonlinear Schrdinger Equation with Delay

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2010年第4期26卷 633-642页

作者： Tao Chen Sheng-fan Zhou Cai-di zhao Admissions and Career Service Shanghai UniversityShanghai 200444China Department of Applied Mathematics Shanghai Normal UniversityShanghai 200234China Department of Mathematics and Information Science Wenzhou UniversityWenzhou 325035China

In this paper,we first prove the existence of the global attractor Aν ∈ C（[-ν,0],2）（ν 0） for a weak damping discrete nonlinear Schrdinger equation with *** we consider an upper semi-continuity of Aν as ν ... 详细信息

关键词： discrete Schrdinger equation delay global attractor upper semi-continuity

Characteristics of elemental carbon and organic carbon in PM_(10) during spring and autumn in Chongqing,China

在线全文

学校读者我要写书评

暂无评论

China Particuology 2007年第4期5卷 255-260页

作者： di Ye Qi zhao Changtan Jiang Jun Chen Xiaoxing Meng Chongqing Academy of Environmental Science Chongqing 400020 China

PM10 （particulate matter with aerodynamic diameter less than 10 μm） samples were collected simultaneously at nine urban sites and one urban background site during two intensive observation campaigns in 2006. Concentrations of elemental carbon （EC） and organic carbon （OC） in PM10 were analyzed using an element analyzer. The characteristics regarding spatial and seasonal distribution patterns of OC and EC concentrations and their contributions to PM10 mass, as well as correlation between OC and EC, were investigated in detail. The average OC and EC concentrations for urban sites were 57.5 ± 20.8 and 8.3 ± 3.9 μg/m^3, respectively, both being around three times higher than those for urban background site. As a whole, EC concentrations did not show distinct seasonal variations, though OC concentrations were generally higher in autumn than in spring. For urban sites, total carbonaceous aerosol （TCA） accounted for 33.2% in spring and 35.0% in autumn of PM10 mass. The OC and EC concentrations were found significantly correlated to each other both in spring and in autumn, implying the existence of similar emission sources such as coal combustion. The OC/EC ratios generally exceeded 2.0, indicating the presence of secondary organic carbon （SOC）, whose estimated concentration for urban Chongqing was 26.7 and 39.4μg/m^3, accounting for 48.9 and 61.9% of the total OC observed in the samples, in spring and in autumn, respectively.

关键词： PM10 Elemental carbon Organic carbon Secondary organic carbon Chongqing

From Spiritual Communication to digital Communication:Rethinking Marx’s Communication Theory in the Information Age

在线全文

学校读者我要写书评

暂无评论

Contemporary Social Sciences 2023年第4期8卷 40-58页

作者： zhao di Yang Qian School of Marxism Communication University of China

Karl Marx and Friedrich Engels introduced the theory of spiritual communication in their influential work,The German Ideology,thereby establishing the Marxist perspective on *** theory has a distinct historical context,meaning,and *** society advances,driven by the proliferation of commodity-based economies and advancements in science and technology,humanity has entered the digital information *** prevailing mode of communication in this era,centered around the Internet and big data,brings great convenience to society but also raises concerns about the potential alienation of both subjective and objective aspects of communication,as well as social *** this backdrop,the rethinking of Marx’s communication theory in the 21st century provides a logical framework and theoretical basis for critiquing the contemporary form of spiritual communication through the digital communication of the information age.

关键词： spiritual communication digital communication alienation

Microstructure and hot ductility behavior of Ni-based superalloy U720Li with boron addition

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第5期40卷 1145-1154页

作者： Guang-di zhao Fang Liu Xi-Min Zang Wen-Ru Sun School of Material and Metallurgy University of Science and Technology LiaoningAnshan 114051China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

High-alloyed superalloy U720 Li is difficult to be processed through the conventional cast and wrought *** is an important strengthening element for superalloys,but the role of boron in the hot ductility of U720 Li alloy is not *** study is focused on the effect of boron addition,in the range ofdition significantly increases the content of eutectic(γ+γ’)and greatly affects the degree of continuity of the grain boundary eutectic(γ+γ’)*** addition dramatically worsens the 1100℃ tensile ductility of conventional cast U720 Li alloy and causes a change in tensile fracture mode from transgranular to *** eutectic(γ+γ’)represents the most effective site for crack *** deteriorates the hot ductility mainly by promoting the continuous precipitation of eutectic(γ+γ’)along the grain boundary.

关键词： Boron U720Li Eutectic(γ+γ’) Hot ductility Fracture mechanism

Numerical study of the kinematic and acoustic characteristics of bubble clusters

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2023年第1期35卷 61-75页

作者： Fu-qiang Deng di zhao Ling-xin Zhang Xue-ming Shao State Key Laboratory of Fluid Power and Mechatronic Systems Department of Engineering MechanicsZhejiang UniversityHangzhou310027China

direct numerical simulations are performed to study single gas/vapor bubble and spherical bubble clusters containing 13–352 vapor bubbles in compressible flow *** numerical results show that the single cavitation bubble keeps spherical during the collapse process,and the far-field acoustic pressure calculated by the Ffowcs William-Hawkings(FW-H)formulation is basically consistent with the analytical solution obtained based on the volume acceleration ***,the spherical bubble cluster collapses layer by layer due to the strong coupling between *** closer to the center of the bubble cluster,the shorter the collapse time and the stronger the non-spherical *** collapse of a bubble cluster would generate multiple acoustic pressure peaks,which cannot be accurately predicted by the volume fluctuation sound source *** size and volume fraction of the bubble cluster have a significant influence on the collapse time and the distribution of sound *** found that when the volume fraction of a bubble cluster is large,the total collapse time is basically the same as that of its corresponding single bubble with the equal *** frequency distribution of sound pressure of a dense bubble cluster is also close to that of its corresponding single *** addition,we found that a bubble cluster with randomly distributed bubble diameters collapses asymmetrically and rebounds in the late stage of the collapse *** above study reveals part of the mechanism of bubble cluster collapse and sound generation,and provides a theoretical basis for the establishment of cavitation noise model.

关键词： Bubble dynamics acoustic radiation spherical bubble clusters Ffowcs William-Hawkings method

Effect of Silicon Content on Thermodynamics of Austenite Decomposition in C-Si-Mn TRIP Steels

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 Iron and Steel Research International 2006年第3期13卷 57-60,73页

作者： ZHU Li-juan WU di zhao Xian-ming State Key Lab of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

Some numerical models such as central atoms model （CAM） and superelement model were used to simulate the thermodynamics of austenite decomposition in the Fe-C-Mn-Si TRIP （transformation induced plasticity） steels. Thermodynamic calculations were carried out under a para-equilibrium （PE） condition. The results show that certain silicon content can accelerate the polygonal ferritic transformation and increase the volume fraction and stability of retained austenite by retarding the precipitation of carbides during the bainitic transformation.

关键词： central atoms model superelement model para-equilibrium austenite decomposition TRIP steel

Asymptotic Smoothing Effect of Solutions to Davey-Stewartson Systems on the Whole Plane

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2007年第11期23卷 2043-2060页

作者： Cai di zhao Yong Sheng LI Sheng Fan ZHOU School of Mathematics and Information Science Wenzhou University Wenzhou 325035 P. R. China Department of Mathematical Sciences South China University of Technology Guangdong 510640 P. R. China Department of Applied Mathematics Shanghai Normal University Shanghai 200234 P. R. China

This paper discusses the Cauchy problem of elliptic-elliptic-type Davey-Stewartson systems with zero-order dissipation on R^2. Making use of the Fourier spectral projector, together with a long time comparison between the solutions to the Davey-Stewartson systems and to an auxiliary problem, we prove that the global attractor in H^1 （R^2） for the addressed Davey-Stewartson systems is a compact subset of H^2（R^2）, and thus reveal the asymptotic smoothing effect of the solutions for the systems.

关键词： Davey-Stewartson systems asymptotic smoothing effect global attractor zero-order dissipation

A Recursive DRL-Based Resource Allocation Method for Multibeam Satellite Communication Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第5期33卷 1286-1295页

作者： Haowei MENG Ning XIN Hao QIN di zhao State Key Laboratory of Integrated Services Networks Xidian University China Academy of Space Technology Institute of Telecommunication Satellite

Optimization-based radio resource management(RRM) has shown significant performance gains on high-throughput satellites(HTSs). However, as the number of allocable on-board resources increases, traditional RRM is difficult to apply in real satellite systems due to its intense computational complexity. Deep reinforcement learning(DRL) is a promising solution for the resource allocation problem due to its model-free advantages. Nevertheless, the action space faced by DRL increases exponentially with the increase of communication scale, which leads to an excessive exploration cost of the algorithm. In this paper, we propose a recursive frequency resource allocation algorithm based on long-short term memory(LSTM) and proximal policy optimization(PPO), called PPO-RA-LOOP,where RA means resource allocation and LOOP means the algorithm outputs actions in a recursive manner. Specifically, the PPO algorithm uses LSTM network to recursively generate sub-actions about frequency resource allocation for each beam, which significantly cuts down the action space. In addition, the LSTM-based recursive architecture allows PPO to better allocate the next frequency resource by using the generated sub-actions information as a prior knowledge, which reduces the complexity of the neural network. The simulation results show that PPO-RA-LOOP achieved higher spectral efficiency and system satisfaction compared with other frequency allocation algorithms.

关键词： Knowledge engineering Spectral efficiency Simulation Satellite broadcasting Neural networks Performance gain Resource management

Magnetogenetics: remote non-invasive magnetic activation of neuronal activity with a magnetoreceptor

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science Bulletin 2015年第24期60卷 2107-2119页

作者： Xiaoyang Long Jing Ye di zhao Sheng-Jia Zhang School of Life Sciences Tsinghua University School of Medicine Tsinghua University IDG/Mc Govern Institute for Brain Research Tsinghua University Tsinghua-Peking Center for Life Sciences Tsinghua University

Current neuromodulation techniques such as optogenetics and deep-brain stimulation are transforming basic and translational neuroscience. These two neuro- modulation approaches are, however, invasive since surgical implantation of an optical fiber or wire electrode is required. Here, we have invented a non-invasive magnetogenetics that combines the genetic targeting of a mag- netoreceptor with remote magnetic stimulation. The noninvasive activation of neurons was achieved by neuronal expression of an exogenous magnetoreceptor, an iron-sulfur cluster assembly protein 1 （Iscal）. In HEK-293 cells and cultured hippocampal neurons expressing this magnetoreceptor, application of an external magnetic field resulted in membrane depolarization and calcium influx in a reproducible and reversible manner, as indicated by the ultrasensitive fluorescent calcium indicator ***, the magnetogenetic control of neuronal activity might be dependent on the direction of the magnetic field and exhibits on-response and off-response patterns for the external magnetic field applied. The activation of this magnetoreceptor can depolarize neurons and elicit trains of action potentials, which can be triggered repetitively with a remote magnetic field in whole-cell patch-clamp recording. In transgenic Caenorhabditis elegans expressing this magnetoreceptor in myo-3-specific muscle cells or mec-4- specific neurons, application of the external magnetic field triggered muscle contraction and withdrawal behavior of the worms, indicative of magnet-dependent activation of muscle cells and touch receptor neurons, respectively. The advantages of magnetogenetics over optogenetics are its exclusive non-invasive, deep penetration, long-term continuous dosing, unlimited accessibility, spatial uniformity and relative safety. Like optogenetics that has gone through decade-long improvements, magnetogenetics, with continuous modification and maturation, will reshape the current landscape of neuromodul

关键词： Magnetogenetics - Optogenetics Iron-sulfur cluster assembly protein Magnetoreceptor Non-invasive and remote activation Neuronalactivity and circuit