检索结果-南通市图书馆

Dynamically Exploring the QCD Matter at Finite Temperatures and Densities:A Short Review

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2021年第8期38卷 23-31页

作者： Shanjin wu chun Shen Huichao Song Center for High Energy Physics Peking UniversityBeijing 100871China Department of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China Department of Physics and Astronomy Wayne State University DetroitMichigan 48201USA RIKEN BNL Research Center Brookhaven National Laboratory UptonNew York 11973USA

We provide a concise review on recent theory advancements towards full-fledged(3+1)D dynamical descriptions of relativistic nuclear collisions at finite baryon ***-ion collisions at different collision energies produce strongly coupled matter and probe the QCD phase transition at the crossover,critical point,and first-order phase transition *** frameworks provide a quantitative tool to extract properties of hot QCD matter and map fireballs to the QCD phase *** challenges are highlighted when confronting current theoretical frameworks with current and forthcoming experimental measurements from the RHIC beam energy scan programs.

关键词： density Dynamical collision

Effects of imperfect pulses on dynamical decoupling using quantum trajectory method

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第12期27卷 182-188页

作者： Lin-Ze He Man-Chao Zhang chun-Wang wu Yi Xie Wei wu ping-Xing Chen Department of Physics College of Science and Liberal ArtsNational University of Defense TechnologyChangsha 410073China interdisciplinary Center for Quantum Information National University of Defense TechnologyChangsha 410073China State Key Laboratory of High Performance Computing National University of Defense TechnologyChangsha 410073China

The dynamical decoupling(DD) method is widely adopted to preserve coherence in different quantum systems. In the case of ideal pulses, its effects on the suppression of noise can be analytically described by the mathematical form of filter function. However, in practical experiments, the unavoidable pulse errors limit the efficiency of DD. In this paper,we study the effects of imperfect pulses on DD efficiency based on quantum trajectories. By directly generating a pseudo noise sequence correlated in time, we can explore the performance of DD with different pulse errors in the typical noise environment. It shows that, for the typical 1/f noise environment, the phase error of operational pulses severely affects the performance of noise suppression, while the detuning and intensity errors have less influence. Also, we get the thresholds of these errors for efficient DD under the given experimental conditions. Our method can be widely applied to guide practical DD experimental implementation.

关键词： pulse imperfections dynamical decoupling

Effect of stress-relief annealing on thermal fatigue cracks for die-casting die steels

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第5期31卷 1164-1176页

作者： Zhi-xiong Bai Xiao-chun wu School of Materials Science and Engineering Shanghai UniversityShanghai200444China

The effect of stress-relief annealing at different stages of thermal fatigue tests on crack growth was investigated using a self-built thermal cycle *** results showed that annealing could limit crack expansion *** reduced dislocation density and released the accumulation of residual *** addition,the strain accumulation in carbides was reduced by this *** was also found that double annealing was even more effective at inhibiting crack expansion compared to single stress-relief *** 1000 cycles,the maximum crack length was reduced by 31.1%and 45.2%for the samples after using the optimal single and double annealing processes,*** single stress-relief annealing,earlier annealing provides more benefit in delaying crack ***,effective double stress-relief annealing requires a suitable time interval between the annealing ***,after 800 cycles,surface hardness decreased significantly accompanied by an increase in the size and number of carbides,and cracks expanded predominantly along grain boundaries.

关键词： Thermal fatigue Steel Carbide Stress-relief annealing Dislocation Residual stress

Human impacts on runoff regime of middle and lower Yellow River

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

Water Science and Engineering 2011年第1期4卷 36-45页

作者： Yan-fang SANG Dong WANG Ji-chun wu Qing-ping ZHU Ling WANG Department of Hydrosciences School of Earth Sciences and Engineering Nanjing University Nanjing 210093 P. R. China China Water International Engineering Consulting Co. Ltd. Beijing 100053 P.. R. China Hydrology Bureau of Yellow River Conservancy Committee of Ministry of Water Resources Zhengzhou 450001 P. R. China

In this study, the 54-year （1950 to 2003） monthly runoff series from February, April, August, and November, as well as the annual runoff series, measured at both Huayuankou and Lijin hydrological stations were chosen as representative data, and the continuous wavelet transform （CWT） was applied to analyze the impacts of human activities on the runoff regime of the middle and lower Yellow River. A point of change in 1970 was first determined, and the observed series before 1970 were considered natural runoff while those after 1970 were restored according to linear trends. Then, the CWT was applied to both the observed and restored runoff series to reveal their variations at multi-temporal scales, including the five temporal ranges of 1-4, 6-8, 9-12, 16-22, and 22-30 years, and the trend at the temporal scale of 54 years. These analysis results are compared and discussed in detail. In conclusion, because of the impacts of human activities, there have been significant changes in the runoff regime in the middle and lower Yellow River since 1970. The decaying tendency of annual runoff has become more pronounced, and the inner-annual distribution of runoff has changed, but human activities have had little impact on the periodic characteristics of runoff.

关键词： time series analysis wavelet analysis runoff human activity Yellow River

VARIATION IN FLOW AND SEDIMENT OF DASHA RIVER AND INFLUENCE OF HUMAN ACTIVITIES ON IT IN SOUTHWEST REGION OF ANHUI PROVINCE

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2006年第2期16卷 109-115页

作者： CHEN Bao-ping ZHANG Jian-chun State Key Laboratory of Estuarine and Coastal Research East China Normal Un＆ersity Shanghai 200062 P. R. China Department of Geography Chizhou Teachers College of A nhui Province Chizhou 247000 P. R. China School of Humanities Hangzhou Teachers College Hangzhou 310036 P. R. China

Soil and water loss is now a major environmental problem in many areas of China, especially in the area of the Dabie Mountain, Anhui Province, which results in environmental degradation and does harm to the people＇s life and production there. Based on the observational records from the Dasha River, the authors analyze the character of the variation in flow and sediment in different flood and dry seasons from 1970 to 2000. The result shows that human activities had significantly reduced the sediment discharge and sediment module, and increased the runoff in low-water seasons since the 1980s. The average contribution rate ofhnman activities to decreasing sediment was 65.67%, and at the same period the contribution rate of runoff and rainfall was about 34.33%. Therefore, it is necessary to take the biological and engineering measures to solve the problem of soil and water loss in the Dasha River watershed.

关键词： river flow sediment discharge human activities effect Dasha River southwest of Anhui Province

Investigation of the effect of quantum measurement on parity-time symmetry

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2022年第6期65卷 36-43页

作者： Wei-Chen Wang Yi Xie Man-Chao Zhang Jie Zhang chun-Wang wu Ting Chen Bao-Quan Ou Wei wu ping-Xing Chen Department of Physics College of Liberal Arts and SciencesNational University of Defense TechnologyChangsha 410073China Interdisciplinary Center for Quantum Information National University of Defense TechnologyChangsha 410073China

Symmetry,including the parity-time(PT)-symmetry,is a striking topic,widely discussed and employed in many *** is well-known that quantum measurement can destroy or disturb quantum ***,can and how does quantum measurement destroy the symmetry of the measured system?To answer the pertinent question,we establish the correlation between the quan-tum measurement and Floquet PT-symmetry and investigate for the first time how the measurement frequency and measurement strength affect the PT-symmetry of the measured system using the 40Ca+*** is already shown that the measurement at high frequencies would break the PT ***,even for an inadequately fast measurement frequency,if the measurement strength is sufficiently strong,the PT symmetry breaking can *** current work can enhance our knowledge of quantum measurement and symmetry and may inspire further research on the effect of quantum measurement on symmetry.

关键词： quantum measurement PT-symmetry ion trap

同方期刊数据库

Dunkl's Theory and Best Approximation by Entire Functions of Exponential Type in L_2-metric with Power Weight

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第10期30卷 1748-1762页

作者： Yong ping LIU chun Yuan SONG School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education

In this paper, we study the sharp Jackson inequality for the best approximation of f ∈L2,k（Rd） by a subspace Ek2（σ）（SEk2（σ））, which is a subspace of entire functions of exponential type （spherical exponential type） at most σ. Here L2,k（Rd） denotes the space of all d-variate functions f endowed with the L2-norm with the weight vk（x）=Пζ∈R＋}（ζ,x）}2k（ζ）,which is defined by a positive subsystem R＋ of a finite root system R Rd and a function k（ζ）：R→R＋ invariant under the reflection group G（R） generated by R. In the case G（R） = Z2d, we get some exact results. Moreover, the deviation of best approximation by the subspace Ek2（σ）（SE2（σ）） of some class of the smooth functions in the space L2,k（Rd） is obtained.

关键词： Reflection group Dunkl transform Bessel function Jackson inequality continuous modulus

Energy-Based Collaborative Spectrum Sensing for Cognitive UWB Impulse Radio

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2015年第2期13卷 174-180页

作者： Wei-Chiang wu chun-Te wu Department of Electrical Engineering Da-Yeh University

This paper focuses on the issue of collaborative spectrum sensing in cognitive ultra wideband（CUWB） impulse radio. We employ energy-based signal detection method and apply the Neyman-Pearson（NP） decision rule to determine the optimum threshold. Two cooperative spectrum sensing schemes are developed in this paper. The decision fusion scheme is based on hard decision, in which each cooperating cognitive user（CU） sends its own local decision to the fusion center（FC）. The FC then makes a final decision according to the majority voting rule. Alternatively, the data fusion scheme is based on soft decision, in which each local CU sends its observed value directly to the FC. The FC combines these values, compares to a threshold and then makes the final decision. The performances of both schemes are studied by using analytical tools and computer simulations. The receiver operating characteristics（ROC）, which reveal the probability of detection versus false-alarm curve, are employed to evaluate the system performance under different scenarios. Simulation results demonstrate that the data fusion scheme outperforms the decision fusion scheme and verify that the collaborative spectrum sensing has practical importance in CUWB networks.

关键词： Impulse collaborative false Spectrum wideband alarm apply receiver verify scenarios

Boundary value problems for two types of degenerate elliptic systems in R^4

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2016年第4期31卷 469-480页

作者： WANG Li-ping WEN Guo-chun School of Mathematics and Information Science Hebei Normal University LMAM School of Mathematical Sciences Peking University

Firstly, the Riemann boundary value problem for a kind of degenerate elliptic sys- tem of the first order equations in R4 is proposed. Then, with the help of the one-to-one correspondence between the theory of Clifford valued generalized regular functions and that of the degenerate elliptic system＇s solution, the boundary value problem as stated above is trans- formed into a boundary value problem related to the generalized regular functions in Clifford analysis. Moreover, the solution of the Riemann boundary value problem for the degenerate elliptic system is explicitly described by using a kind of singular integral operator. Finally, the conditions for the existence of solutions of the oblique derivative problem for another kind of degenerate elliptic system of the first order equations in R4 are derived.

关键词： Clifford analysis generalized regular function degenerate elliptic system Riemann boundaryvalue problem oblique derivative problem.