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Solitary Excitations of Dipolar Bosons in Optical Lattice under Magnetic Fields

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Communications in Theoretical Physics 2006年第2X期46卷 233-238页

作者： wang shi-En Department of Physics Honghe University Mengzi 661100 China Department of Materials Tsinghua University Beijing 100084 China Department of Physics Wenshang Normal Academy Wenshaag 663000 China Department of Physics Beijing Normal University Beijing 100875 China

We obtain the multisolitary solutions of the extended Bose-Hubbard model which describes dipolar Bose- Einstein condensates in optical lattices under time-dependent magnetic fields, and indicate that the nonlinearity is due to both on-site short-range interactions and also （long-range） dipole-dipole interactions which can act between neighboring sites. The discrete breathers as nonlinear excitations are always oscillatory in time and can also be spatially localized, while the oscillatory frequencies are determined by an external field. We show that these excitations will be observable and discuss how the parameters can be tuned in future experiments.

关键词： solitary excitation extended Bose-Hubbard model bosons optical lattice

Eutectic precipitates and microstructure of electroslag remelted 15Cr-22Ni austenitic heat-resistant steel with varying Nb contents

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Journal of Iron and Steel Research International 2022年第11期29卷 1823-1835页

作者： Hao-chi Xu Cheng-bin shi Xin Zhu shi-jun wang Jing Li shi-zhou wang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing(USTB)Beijing 100083China

The microstructure,eutectic carbides and intermetallic compounds in as-cast ingots with varying Nb contents produced by electroslag remelting were *** solidification behavior,microsegregation of alloying elements and its influence on precipitates were *** increase in Nb content from 0.64 to 1.40 wt.%has no effect on the dendrite morphology and secondary dendrite arm *** total area fraction of eutectic NbC and Laves phase in as-cast ingots increases with the increase in Nb *** eutectic precipitates in the ingot with 0.64 wt.%Nb are mainly NbC,and the others are Fe_(2)Nb-type Laves *** the Nb content of the steel significantly promotes the precipitation of Laves phases and lowers the precipitation temperature of NbC eutectic *** carbide M_(2)C is precipitated only in the ingot with 1.4 wt.%*** average concentration of Nb in both interdendritic and intragranular regions increases with the increase in Nb content of the steel,leading to a change in the morphology of Fe_(2)Nb-type Laves phase from honeycomb to *** the Nb content exerts little effect on the microsegregation degrees of Si,Mo,Cr and Ni in the steel.

关键词： Eutectic carbides Fe2Nb-type Laves phase Austenitic heat-resistant steel Microsegregation Electroslag remelting

Optimal design of vibration absorber using minimax criterion with simplified constraints

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Acta Mechanica Sinica 2012年第3期28卷 848-853页

作者： Jie Fang shi-Min wang Qi wang School of Aeronautics Science and Engineering Beihang University100191 BeijingChina

In this paper, a minimax design of damped dynamic vibration absorber for a damped primary system is investigated to minimize the vibration magnitude peaks. Moreover, to reduce the sensitivity of the primary system response to variations of the forcing frequency for a two- degree-of-freedom system, the primary system should have two equal resonance magnitude peaks. To meet this re- quirement, a set of simplified constraint equations includ- ing distribution characteristics of the resonant frequencies of the primary system is established for the minimax objective function. The modified constraint equations have less un- known variables than those by other authors, which not only simplifies the computation but also improves the accuracy of the optimal values. The advantage of the proposed method is illustrated through numerical simulations.

关键词： Minimax Optimization Dynamic vibrationabsorber (DVA) Sensitivity

Investigation on Mesh and Sideband Vibrations of Helical Planetary Ring Gear Using Structure, Excitation and Deformation Symmetries

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Chinese Journal of Mechanical Engineering 2018年第6期31卷 55-67页

作者： shi-Yu wang Chanannipat Meesap School of Mechanical Engineering Tianjin University 300072 Tianjin China Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin University Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin University 300072 Tianjin China

Time?variant excitations in planetary gear trains can cause excessive noise and vibration and even damage the system on a permanent basis. This paper focuses on the elastic vibrations of a helical planetary ring gear subjected to mesh and planet?pass excitations. Motivated by the structure, excitation and deformation symmetries, this paper proposes dual?frequency superposition and modulation methods to capture the mesh and sideband vibrations. The transi?tion between ring gear tooth and planet is introduced to address the excitations and vibrations. The phasing e ect of ring gear tooth and planet on various deformations is formulated. The inherent connections between the two types of vibrations are identified. The vibrations share identical exciting rules and the wavenumber and modulating signal order both equal the linear combination of tooth and planet counts. The results cover in?plane bending and extensional, out?of?plane bending and torsional deformations. Main findings are verified by numerical calculation and comparisons with the open literature. The analytical expressions can be used to determine whether the sideband is caused by component fault or only by elastic vibration. The methods can be extended to other power?transmission systems because little restriction is imposed during the analysis.

关键词： Helical planetary ring gear Typical vibration modes Planet phasing Sideband

LEM-DEM coupling for slope stability analysis

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Science China(Technological Sciences) 2020年第2期63卷 329-340页

作者： XU WenJie wang shi BILAL Manzoor State Key Laboratory of Hydroscience and Hydraulic Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China

Slope stability analysis is a keen area of interest to researchers of geotechnical engineering and geological hazards. To date, the most popular approach applied in slope engineering design is the limit equilibrium method(LEM). However, for this method,some assumptions are required when obtaining the sliding force and the resistance force on the slide face. The discrete element method(DEM) presents an advantage in the calculation of the interaction forces between adjacent blocks without *** paper introduces a new slope stability analysis based on coupling of both approaches, herein referred to as LEM-DEM. The main LEM-DEM procedure is to transform the slice model of a slope in LEM into the DEM model and obtain the sliding force and the resistance force to calculate the factor of stability(Fos). The sensitivity analysis of the parameters in DEM, such as normal and shear stiffness, was conducted to illustrate that LEM-DEM suggests higher contact stiffness. A comparison between the Fos values in DEM and LEM-DEM was also conducted to indicate the rationality and advantages of LEM-DEM, especially for a gentle slope with a changing shear force direction in the slice model where the interslice forces in LEM are ***, this study carried out a 3 D landslide stability analysis extension, along with the results, for the proposed method.

关键词： limit equilibrium method(LEM) discrete element method(DEM) slope stability factor of stability(Fos) coupling

Northeastern Asia humidification at the end of the Miocene drives the boost of mammalian dispersals from the Old to New World

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Journal of Palaeogeography 2023年第1期12卷 50-68页

作者： Qigao Jiangzuo shi-Qi wang Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking UniversityBeijing 100871China Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100871China CAS Center for Excellence in Life and Paleoenvironment Beijing 100871China Division of Paleontology American Museum of Natural HistoryNew YorkNY 10024-5102USA

Mammals have high dispersal ability,and many lineages can spread across the continents when a landbridge ***,we summarize the dispersal of mammals between the Old and New World at the end of the *** analysis suggested that the three phases of dispersal represented the largest dispersal tide during the Neogene,and the direction of dispersal is dominated by being from the Old to New *** from the components that crossed the dispersal corridor,the Arctic environment near the Beringia corridor in the first phase(~7.5 Ma)is a mixed environment,and in the second phase(~6.5 Ma)is an open environment,and in the third phase(~5.8 Ma and continue to the Pliocene)is a wooded(closed)environment.A clear trend of eastern Asian humidification driven by Asian monsoon and the global C4 grassland expansion explain this dispersal *** boost of mammalian dispersals is controlled by the heterogeneity of environmental changes in different continents.

关键词： Eastern asia North America Carnivora Dispersal Late miocene

Zero-voltage switching converter absorbing parasitic parameters for super high frequency induction heating

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 564-571页

作者： Zheng-shi wang Hui-ming CHEN School of Electrical Engineering Zhejiang University Hangzhou 310027 China

This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.

关键词： Induction heating Super high frequency Soft-switching converter Parasitic parameters

Non-metallic inclusions in electroslag remelting:a review

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Journal of Iron and Steel Research International 2021年第12期28卷 1483-1503页

作者： Cheng-bin shi shi-jun wang Jing Li Jung-wook Cho Institute of Advanced Steel State Key Laboratory of Advanced MetallurgyUniversity of Science and Technology Beijing(USTB)Beijing100083China Graduate Institute of Ferrous and Energy Materials Technology Pohang University of Science and Technology(POSTECH)Pohang790-784Republic of Korea

Non-metallic inclusion in electroslag remelting is a constant topic that has been studied for *** results and conclusions are obtained on some of the subjects from these previous *** differences originate in part from different experimental conditions,including original inclusion chemistries in consumable electrode,slag composition,oxygen level,liquid metal compositions,deoxidation schemes,and melting rates of electroslag *** advances in the operating practices of inclusion control in electroslag remelting production are *** evolution during the electroslag remelting and related processing parameters are also reviewed and *** role of the reoxidation of liquid steel during electroslag remelting on oxide inclusion composition is *** generation of inclusions in remelted ingot is critically *** and remaining issues are noted.

关键词： Non-metallic inclusion Electroslag remelting Inclusion removal Reoxidation

Impact of frailty on outcomes of elderly patients undergoing percutaneous coronary intervention: A systematic review and metaanalysis

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World Journal of Clinical Cases 2024年第1期12卷 107-118页

作者： shi-shi wang wang-Hao Liu Department of Emergency Medicine Huzhou Third Municipal HospitalThe Affiliated Hospital of Huzhou UniversityHuzhou 313000Zhejiang ProvinceChina Department of Geriatrics Huzhou Third Municipal Hospitalthe Affiliated Hospital of Huzhou UniversityHuzhou 313000Zhejiang ProvinceChina

BACKGROUND Frailty is a common condition in elderly patients who receive percutaneous coronary intervention(PCI).However,how frailty affects clinical outcomes in this group is *** To assess the link between frailty and the outcomes,such as in-hospital complic-ations,post-procedural complications,and mortality,in elderly patients *** The PubMed/MEDLINE,EMBASE,Cochrane Library,and Web of Science databases were screened for publications up to August *** primary outcomes assessed were in-hospital and all-cause mortality,major adverse cardiovascular events(MACEs),and major *** Newcastle-Ottawa Scale was used for quality *** Twenty-one studies with 739693 elderly patients undergoing PCI were *** was consistently associated with adverse *** patients had significantly higher risks of in-hospital mortality[risk ratio:3.45,95%confidence interval(95%CI):1.90-6.25],all-cause mortality[hazard ratio(HR):2.08,95%CI:1.78-2.43],MACEs(HR:2.92,95%CI:1.85-4.60),and major bleeding(HR:4.60,95%CI:2.89-7.32)compared to non-frail *** Frailty is a pivotal determinant in the prediction of risk of mortality,development of MACEs,and major bleeding in elderly individuals undergoing percutaneous coronary intervention.

关键词： Frailty Elderly Percutaneous coronary intervention Systematic review Meta-analysis