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Experimental investigation of the fluctuations in nonchaotic scattering in microwave billiards

Chinese Physics B 2019年第10期28卷 160-171页

作者： Runzu zhang weihua zhang Guozhi Chai Liang Huang School of Physical Science and Technology Lanzhou UniversityLanzhou 730000China Key Laboratory for Magnetism and Magnetic Materials of MOE Lanzhou UniversityLanzhou 730000China

We report on the experimental investigation of the properties of the eigenvalues and wavefunctions and the fluctuation properties of the scattering matrix of closed and open billiards, respectively, of which the classical dynamics undergoes a transition from integrable via almost integrable to fully chaotic. To realize such a system, we chose a billiard with a 60° sector shape of which the classical dynamics is integrable, and introduced circular scatterers of varying number, size,and position. The spectral properties of generic quantum systems of which the classical counterpart is either integrable or chaotic are universal and well understood. If, however, the classical dynamics is pseudo-integrable or almost-integrable,they exhibit a non-universal intermediate statistics, for which analytical results are known only in a few cases, e.g., if it corresponds to semi-Poisson statistics. Since the latter is, above all, clearly distinguishable from those of integrable and chaotic systems, our aim was to design a billiard with these features which indeed is achievable by adding just one scatterer of appropriate size and position to the sector billiard. We demonstrated that, while the spectral properties of almostintegrable billiards are sensitive to the classical dynamics, this is not the case for the distribution of the wavefunction components, which was analyzed in terms of the strength distribution, and the fluctuation properties of the scattering matrix which coincide with those of typical, fully chaotic systems.

关键词： wave chaos quantum billiards microwave billiards random matrix theory

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玻璃材料的宏微观辐照效应

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中国科学：物理学、力学、天文学 2024年第8期54卷 1-26页

作者：魏来凌雪吴俊豪郑卫芳张立国张伟华崔一南中国地质大学(北京)工程技术学院北京100083 清华大学航天航空学院应用力学教育部重点实验室北京100084 中国原子能科学研究院放射化学研究所北京102413 清华大学核能与新能源技术研究院北京100084

玻璃材料在核工业及航天航空、深空探测等领域发挥着重要的作用.然而,强辐照效应常常会导致玻璃材料变色、脆化、光学性能退化等,极大制约了其服役的可靠性和耐久性.设计抗辐照玻璃的核心便是深入理解其辐照损伤的宏微观物理过程,然而... 详细信息

玻璃材料在核工业及航天航空、深空探测等领域发挥着重要的作用.然而,强辐照效应常常会导致玻璃材料变色、脆化、光学性能退化等,极大制约了其服役的可靠性和耐久性.设计抗辐照玻璃的核心便是深入理解其辐照损伤的宏微观物理过程,然而鲜有论文对其展开深入系统的总结和论述.本文从辐照效应的位移损伤和离子损伤原子级物理图像出发,阐述了玻璃中色心缺陷的形成机制,综述了损伤演化带来的光学及力热特性的变化,继而总结了不同损伤特征的实验监测方法及宏微观损伤的多尺度计算方法和模型,旨在为抗辐照及耐辐照玻璃设计提供指导和依据.

关键词：抗辐照玻璃辐照效应多尺度模拟掺杂改性

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Changes in somatosensory evoked potentials elicited by stimulation of upper-limb and lower-limb nerves in amyotrophic lateral sclerosis patients

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Neural Regeneration Research 2011年第26期6卷 2018-2021页

作者： Ying Zheng Zhaohuan zhang weihua Wu Zhongxin Zhao Department of Neurology Changzheng Hospital Second Military Medical University of Chinese PLA Shanghai 200003 China

This study observed the changes in somatosensory evoked potentials between patients with amyotrophic lateral sclerosis （ALS） and healthy controls to evaluate the function of the central deep somatosensory pathway. In patients with ALS, 28 patients （54%） showed an abnormality in somatosensory evoked potentials. All had abnormal lower limb somatosensory evoked potentials. Compared with healthy controls, the abnormality in somatosensory evoked potential was characterized by prolonged N20, P2, N2 latency and central conduction time, with or without a decrease in wave amplitude or disappearance of waveform. Results showed marked alterations in the somatosensory evoked potential in cortical components of the upper and lower limb in 54% of patients with ALS, and confirmed that patients with ALS may also have a defective deep somatosensory pathway, particularly an abnormal central deep somatosensory pathway.

关键词： amyotrophic lateral sclerosis somatosensory evoked potential central conduction time neural regeneration

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Microwave-promoted Synthesis of Novel Fused Osthole Analogues

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Chinese Journal of Chemistry 2016年第12期34卷 1344-1352页

作者： Mingzhi zhang Rongrong zhang Jiaqun Wang Xiang Yu Yaling zhang Qingqing Wang weihua zhang Jiangsu Key Laboratory of Pesticide Science College of Sciences Nanjing Agricultural University Nanjing Jiangsu 210095 China

Osthole is a natural coumarin derivative and has a broad scope of biological activities. Two series of novel fused osthole analogues were designed, and synthesized through a highly efficient microwave-promoted synthetic proto- col via the reaction of 4-hydroxycoumarins and fl-ketoesters. The reaction conditions including solvent, catalyst, microwave power and irradiation time were also optimized. The pyrano[3,2-c]chromene-2,5-diones and furo[3,2-c]- coumarins were obtained through two distinct intramolecular cyclization processes, and the proposed mechanism was also discussed.

关键词： osthole microwave-promoted synthesis pyrano[3,2-c]chromene-2,5-diones furo[3,4-c]coumarins mechanism

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Numerical simulation and optimization of aerodynamic uplift force of a high-speed pantograph

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Railway Engineering Science 2022年第1期30卷 117-128页

作者： Zhiyuan Dai Tian Li Ning Zhou Jiye zhang weihua zhang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

Aiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent,and their magnitudes do not satisfy the corresponding standard, the aerodynamic uplift forces of pantographs with baffles are numerically investigated, and an optimization method to determine the baffle angle is proposed. First, the error between the aerodynamic resistances of the pantograph obtained by numerical simulation and wind tunnel test is less than 5%, which indicates the accuracy of the numerical simulation method. Second, the original pantograph and pantographs equipped with three different baffles are numerically simulated to obtain the aerodynamic forces and moments of the pantograph *** different angles for the baffles are-17°, 0° and 17°.Then the multibody simulation is used to calculate the aerodynamic uplift force of the pantograph, and the optimal range for the baffle angle is determined. Results show that the lift force of the baffle increases with the increment of the angle in the knuckle-downstream condition, whereas the lift force of the baffle decreases with the increment of the angle in the knuckle-upstream condition. According to the results of the aerodynamic uplift force, the optimal angle of the baffle is determined to be 4.75° when the running speed is 350 km/h, and pantograph–catenary contact forces are 128.89 N and 129.15 N under the knuckledownstream and knuckle-upstream operating conditions,respectively, which are almost equal and both meet the requirements of the standard EN50367:2012.

关键词： High-speed pantograph Aerodynamic uplift force Baffle Numerical simulation Multibody simulation

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A bibliometric review of driver information processing and application studies

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第5期10卷 787-807页

作者： Jingyu Li weihua zhang Zhongxiang Feng Lulu Liu Haoxue Guan College of Civil Engineering Hefei University of TechnologyHefei 230009China School of Automotive and Transportation Engineering Hefei University of TechnologyHefei 230009China

With the continuous development of information technology,the information environment while driving is constantly being enriched,and driver information processing and application are also dynamically *** information processing and application can better provide information services and is particularly important for traffic *** on VOSviewer bibliometric software,this paper explores the research hotspots and future development trends of the driver information processing and application fields using the Web of Science(WoS)core collection as the data *** results show that the field has a long history and has grown steadily in recent *** United States,China and Germany are the top three countries in terms of the number of published articles.“Situational awareness and visual load”,“route selection under variable information signs”,“en-route information and behaviour”and“new information technology attitudes”are important knowledge bases for driver information processing and ***-route information sources,human-computer interaction,and autonomous vehicle information are the research trends of the driver information processing and application *** results of this research can help people comprehensively and systematically understand the current situation of driver information processing and application research,provide directions for future driver information processing and application research,and promote the engineering application of such research.

关键词： Traffic safety Human factor Information processing Driving behaviour Bibliometric analysis

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Restoration technologies of damaged paddy in hilly post-mining and subsidence-stable area of Southwest China

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International Journal of Agricultural and Biological Engineering 2015年第2期8卷 46-57页

作者： Zhong Shouqin Wei Chaofu Liu Bo zhang weihua Du Jing zhang Shichao Key Laboratory of Arable Land Conservation(Southwest China) Ministry of AgricultureChongqing 400715China College of Resources and Environment Southwest UniversityChongqing 400715China

The paddy fields and water storage facilities are seriously damaged by the coal mine subsiding in the hilly post-mining and subsidence-stable areas in China,which make the farmers there being suffered greatly from the lack of water for traditional rice cultivation and daily *** purpose of this paper is to find a method to restore the damaged paddy fields,thereby promoting sustainable development of land resources,and alleviating the contradiction between people and land,as well as creating a more inhabitable *** research methodology included field experiments,cultivated observation,and field *** paper selected the Songzao Mining Area as the research area,and focused on the restoration technologies of damaged paddy fields,through the following four different measures at three experimental fields:(1)Traditional repeated cattle plowing(CK);(2)Water retention agent with repeated cattle plowing(W&C);(3)Film without holes under tilth depth(FO);and(4)Film with holes under tilth depth(FW).At last,a contrastive analysis of the four measures was made according to the results of the *** results show that the use of water retaining agent with repeated cattle plowing(W&C)can be the most appropriate method to restore the damaged paddy field in the hilly post-mining and subsidence-stable area in southwest *** with the other three measures,its water productivity is the maximum(0.81 kg/m3),and the net income is the highest(1403$/hm^(2)).What’s more,it is simple,short time-consuming,and low cost,which is benefit to generalize the use of this restoration technology.

关键词： land restoration damaged paddy field post-mining and subsidence-stable area water consumption hilly areas

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Computer comparisons in the presence of performance variation

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Frontiers of Computer Science 2020年第1期14卷 21-41页

作者： Samuel IRVING Bin LI Shaoming CHEN Lu PENG weihua zhang Lide DUAN Louisiana State University Baton RougeLA 70803USA Shanghai Institute of Intelligent Electronics&Systems Shanghai 201203China Software School Fudan UniversityShanghai 201203China Shanghai Key Laboratory of Data Science Fudan UniversityShanghai 200433China University of Texas at San Antonio San AntonioTX 78249USA

Performance variability,stemming from nondeterministic hardware and software behaviors or deterministic behaviors such as measurement bias,is a well-known phenomenon of computer systems which increases the difficulty of comparing computer performance metrics and is slated to become even more of a concern as interest in Big Data analytic *** methods use various measures(such as geometric mean)to quantify the performance of different benchmarks to compare computers without considering this variability which may lead to wrong *** this paper,we propose three resampling methods for performance evaluation and comparison:a randomization test for a general performance comparison between two computers,bootstrapping confidence estimation,and an empirical distribution and five-number-summary for performance *** results show that for both PARSEC and highvariance BigDataBench benchmarks 1)the randomization test substantially improves our chance to identify the difference between performance comparisons when the difference is not large;2)bootstrapping confidence estimation provides an accurate confidence interval for the performance comparison measure(e.g.,ratio of geometric means);and 3)when the difference is very small,a single test is often not enough to reveal the nature of the computer performance due to the variability of computer *** further propose using empirical distribution to evaluate computer performance and a five-number-summary to summarize computer *** use published SPEC 2006 results to investigate the sources of performance variation by predicting performance and relative variation for 8,236 *** achieve a correlation of predicted performances of 0.992 and a correlation of predicted and measured relative variation of ***,we propose the utilization of a novel biplotting technique to visualize the effectiveness of benchmarks and cluster machines by *** illustrate the results and concl

关键词： performance of systems variation performance attributes measurement evaluation modeling simulation of multiple-processor systems experimental design Big Data

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不同级别横风下虚拟轨道车辆动力学性能研究

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现代交通与冶金材料 2024年第2期4卷 43-48,76页

作者：张弛朱涛张卫华王超黄文杰西南交通大学轨道交通运载系统全国重点实验室四川成都610031 中车南京浦镇车辆有限公司江苏南京210031

为了研究虚拟轨道车辆在不同级别横风下的动力学性能,基于非线性胎地耦合关系建立了3编组虚拟轨道车辆多体动力学模型,研究虚拟轨道车辆在AW0和AW3状态下,不同级别横风对其胎地垂向力、抗倾覆稳定性、抗侧滚性能等主要动力学指标的影响... 详细信息

为了研究虚拟轨道车辆在不同级别横风下的动力学性能,基于非线性胎地耦合关系建立了3编组虚拟轨道车辆多体动力学模型,研究虚拟轨道车辆在AW0和AW3状态下,不同级别横风对其胎地垂向力、抗倾覆稳定性、抗侧滚性能等主要动力学指标的影响。结果表明:AW0状态且低速工况下,不同风级的风载和运行速度对各编组车辆影响较小,车辆动力学性能等指标基本一致;AW3状态下,各个指标值均随着运行速度和风级的提高而增大,且AW0状态下车辆的抗倾覆稳定性总体上优于AW3状态;针对各编组车辆而言,中间车的抗侧滚性能优于头车和尾车,其中尾车的抗侧滚性能最差,但各编组之间的抗倾覆稳定性相差不大。

关键词：车辆动力学虚拟轨道车辆胎地耦合关系抗倾覆稳定性抗侧滚性能

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Research on the classification for road traffic visibility based on the characteristics of driving behaviour–a driving simulator experiment

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Journal of Intelligent and Connected Vehicles 2020年第1期3卷 30-36页

作者： Kun Wang weihua zhang Zhongxiang Feng Cheng Wang College of Civil Engineering Hefei University of TechnologyHefeiChina School of Automobile and Traffic Engineering Hefei University of TechnologyHefeiChina

Purpose–The purpose of this paper is to performﬁne classiﬁcation of road trafﬁc visibility based on the characteristics of driving behavior under different visibility ***/methodology/approach–A driving simulator experiment was conducted to collect data of speed and lane *** was used to explore the difference in driving behavior under different visibility ***–The results show that only average speed is signiﬁcantly different under different visibility *** the visibility reducing,the average vehicle speed *** road visibility conditions in a straight segment can be divided intoﬁve levels:less than 20,20-30,35-60,60-140 and more than 140 *** road visibility conditions in a curve segment can be also divided into four levels:less than 20,20-30,35-60 and more than 60 ***/value–Aﬁne classiﬁcation of road trafﬁc visibility has been performed,and these classiﬁcations help to establish more accurate control measures to ensure road trafﬁc safety under low-visibility conditions.

关键词： Speed Driving simulator experiment Lane position Low visibility Trafﬁc safety

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