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Analysis of some large-scale nonlinear stochastic dynamic systems with subspace-EPC method

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Science China(Physics,Mechanics & Astronomy) 2011年第9期54卷 1631-1637页

作者： er GuoKang IU VaiPan Faculty of Science and Technology University of Macao Macao SAR China

The probabilistic solutions to some nonlinear stochastic dynamic (NSD) systems with various polynomial types of nonlinearities in displacements are analyzed with the subspace-exponential polynomial closure (subspace-EPC) method. The space of the state variables of the large-scale nonlinear stochastic dynamic system excited by Gaussian white noises is separated into two subspaces. Both sides of the Fokker-Planck-Kolmogorov (FPK) equation corresponding to the NSD system are then integrated over one of the subspaces. The FPK equation for the joint probability density function of the state variables in the other subspace is formulated. Therefore, the FPK equations in low dimensions are obtained from the orig.nal FPK equation in hig. dimensions and the FPK equations in low dimensions are solvable with the exponential polynomial closure method. Examples about multi-degree-offreedom NSD systems with various polynomial types of nonlinearities in displacements are given to show the effectiveness of the subspace-EPC method in these cases.

关键词： nonlinear stochastic dynamic systems large-scale systems probability density function Fokker-Planck-Kolmogorov equation subspace-EPC

Efficacy of methanol-water extract of Inula helenium root against oxidative DNA damage

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Journal of Traditional Chinese Medicine 2021年第2期41卷 293-300页

作者： Onder Aybastıer Bursa Uludag University Faculty of Science and ArtsDepartment of ChemistryBursa 16059Turkey

OBJECTIVE:To investig.te the efficacy of methanol-water extract of Inula helenium root against oxidative DNA ***:Antioxidant properties of methanol-water extract of Inula helenium root were revealed by 2,2'-azinobis(3-ethylbenzothiazoline-6-suphonic acid)di-ammonium salt(ABTS),Folin-Ciocalteu and hig.-performance liquid chromatography(HPLC)*** effect against oxidative DNA base damage was determined analyzing oxidative DNA base damage products by GC-MS/***:The methanol-water extract of Inula helenium root showed good antioxidant capacity[32.20 mg trolox equivalents(TE)/g dried weig.t(dw)by ABTS method,54.53 mg TE/g dw by chromium reducing antioxidant capacity method]and total phenolic content[29.83 mg gallic acid equivalent(GAE)/g dw].The chlorogenic acid,ferulic acid,rosmarinic acid and caffeic acid were determined in the extract by *** chlorogenic acid,ferulic acid and Inula helenium root extract were revealed to inhibit the oxidative DNA base damage by GC-MS/***:The studies showed a crucial decrease in the amount of the DNA base damage products when antioxidants were *** results showed that ferulic acid has better inhibition than chlorogenic acid for DNA *** methanol-water extract of Inula helenium root was determined to inhibit the oxidative DNA damage.

关键词： Inula DNA damage Antioxidants Phytochemicals Gas chromatography-mass spectrometry

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Monopole Charge Domain in Hig.-Gain Gallium Arsenide Photoconductive Switches

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Chinese Physics Letters 2002年第8期19卷 1119-1121页

作者： Shi Wei, Chen er-Zhu Department of Applied Physics Xi"an University of Technology

Considering that semi-insulating gallium arsenide photoconductive switches can be trig.ered into the hig. gain mode and no reliable theories can account for the observed transient characteristics, we propose the monopole charge domain model to explain the peculiar switching phenomena occurring in the hig. gain mode and we discuss the requirements for the lock-on switching. During operation on this mode, the applied field across the switch and the lock-on field are all larger than the Gunn threshold field. Our developed monopole charge domain is based on the transferred-electron effect, but the domain is only composed of large numbers of electrons piled up due to the negative differential mobility. Using the model and taking the physical mechanism of the avalanche impact ionization and recombination radiation into consideration, we interpret the typical phenomena of the lock-on effect, such as the time delay between the beginning of optical illumination and turning-on of the switch, and the conduction mechanism of the sustaining phase. Under different conditions of bias field intensity and incident lig.t energy, the time delay of the switching is calculated. The results show that the physical mechanisms of impact ionization and recombination radiation occurring in the monopole charge domain are responsible for the lock-on switching

关键词： Time delay

Northern China maximum temperature in the summer of 1743: A historical event of burning summer in a relatively warm climate background

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Chinese Science Bulletin 2004年第23期49卷 2508-2514页

作者： ZHANGDe'er DemareeGaston NationalClimateCenterofChina Beijing100081China RoyalMeteorologicalInstitute BrusselsBelgium

In the context of historical climate records of China and early meteorological measurements of Beijing discovered recently in Europe, a study is undertaken on the 1743 hottest summer of north China over the last 700 a, cov- ering Beijing, Tianjin, and the provinces of Hebei, Shanxi and Shandong, with the hig.est temperature reaching 44.4℃ in July 1743 in Beijing, in excess of the maximum climate record in the 20th century. Results show that the related weather/climate features of the 1743 heat wave, e.g., flood/ drought distribution and Meiyu activity and the external forcings, such as solar activity and equatorial Pacific SST condition are the same as those of the 1942 and 1999 heat events. It is noted that the 1743 burning summer event oc- curs in a relatively warm climate background prior to the Industrial Revolution, with a lower level of CO2 release.

关键词： 1743年中国夏季气温气候背景历史二氧化碳

Comparison of engineering failures and seismic responses of 500 kV transformer-bushing systems in the 2022 Luding earthquake

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Earthquake Engineering and Engineering Vibration 2024年第4期23卷 1029-1041页

作者： Zhu Wang Wu Ming’er Xie Qiang Department of Structural Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures(Tongji University) Shanghai 200092China

Cemented and mechanically clamped types of end fittings(fitting-C and fitting-M)are commonly used in transformer *** the Luding Ms 6.8 earthquake that occurred in China on September 5,2022,all transformer bushings with the two types of end fittings in a 500 kV substation were ***-earthquake field investig.tions were conducted,and the failures of the two types of bushings were *** elementary simulation models of the transformer-bushing systems were developed to simulate the engineering failures,and further compute their seismic responses for *** results indicate that the hitch lugs of the connection flange are structurally harmful to seismic ***-M can decrease the bending stiffness of the bushing due to the flexible sealing rubber *** it provides a more flexible connection that dissipates energy,the peak accelerations and relative displacements at the top of the bushing are sig.ificantly lower than those of the bushing with *** with fitting-C,fitting-M transfers the hig.-stress areas from the connection flange to the root of the porcelain,so the latter becomes the most vulnerable ***-M increases the failure risk of the low-strength porcelain,indicating the unsuitability of applying it in hig.-intensity fortification regions.

关键词： transformer bushing end fitting Luding earthquake,engineering failure seismic responses

Debris flow susceptibility and propagation assessment in West Koyulhisar, Turkey

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Journal of Mountain Science 2020年第11期17卷 2611-2623页

作者： Ali POLAT Dursun erİK Provincial Directorate of Disaster and Emergency Sivas 58050Turkey Republic of Turkey General Directorate of Hig.way 16.DistrictSivas 58049Turkey

Turkey is hig.ly prone to landslides because of the geological and geographic *** study area,which is located in a tectonically active region,has been sig.ificantly affected by mass *** type landslides are frequently observed due to this *** study aims at determining the source area and propagation of debris flows in the study *** used the heuristic method to extract source areas of debris flow,and then used receiver operating characteristic(ROC)curve analysis to assess the performance of the method,and finally calculated the Area under curve(AUC)values being 83.64%and 80.39%for the success rate and prediction rate,*** calculated potential propagation area and runout distance with Flow-R *** conclusion,the obtained results(susceptibility map,propagation and runout distance)are very important for decisionmakers at the region located on an active fault zone,which is hig.ly prone to natural *** outputs of this study could be used in site selection studies,desig.ing erosion prevention systems and protecting existing human-made structures.

关键词： Koyulhisar Debris flow Flow path assessment Heuristic method Landslide susceptibility mapping Geographical Information System(GIS)

Effects of Density—Dependent Bag Constant and Strange Star Rotation

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Communications in Theoretical Physics 2003年第1期39卷 89-90页

作者： ZHOUQiao－er GUOHua DepartmentofTechnicalPhysicsandMOELaboratoryofHeavyIonPhysics PekingUniversityBeijing100871China DepartmentofTechnicalPhysicsandMOELaboratoryofHeavyIonPhysics PekingUniversit

With the emphasis on the effects of the density-dependent bag constant and the rotation of strange star the limiting mass of strange star is calculated. The obtained results show that the limiting mass and the corresponding radius of strange star increase as the rotation frequency increases, and tend to be lowered when the density-dependent bag constant is considered.

关键词： density-dependent bag constant rotation frequency of strange star limiting mass and radius of strange star

Asymmetric catalytic anhydride openings via carbon-based nucleophiles

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Chinese Chemical Letters 2014年第1期25卷 1-8页

作者： Chen Zheng Fen-er Chen Department of Chemistry Fudan University

The asymmetric desymmetrization of cyclic anhydrides via the addition of carbon-based nucleophiles has been the focus of considerable levels of interest because it leads to optically active products. Over the past 20 years, a variety of different catalytic asymmetric alkylation reactions have been developed for the desymmetrization of cyclic anhydrides using different metal reagents as nucleophiles and using chiral lig.nds. The purpose of this review is to provide an overview of sig.ificant developments in this field. ~ 2013 Fen-er Chen. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rig.ts reserved.

关键词： Cyclic anhydrides Carbon-based nucleophiles Chiral lig.nds Asymmetric catalysis Metal reagents

Characteristics of American Scholars’Research on Chinese Medical Classics and Their Contributions

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Chinese Journal of Integrative Medicine 2020年第8期26卷 629-632页

作者： WANG er-liang CHEN Xiao School of Basic Medicine Shanghai University of Traditional Chinese MedicineShanghai 201203China

Chinese medical classics are important carriers for the inheritance,innovation and development of academic thoughts of Chinese medicine(CM),containing rich thoughts on diagnosis and treatment as well as therapeutic principles of *** international exchange of CM has a very long *** the development of society,Western scholars in modern times are deepening their researches on Chinese medical *** would provide a new way for promoting CM in Western countries to investig.te researches made by famed American scholars and their academic viewpoints.

关键词： Chinese medicine classics international exchange American scholar