检索结果-南通市图书馆

Acta Geochimica 2017年第3期36卷 367-369页

作者： Sujin kang Kyoung-Hoon shin Jung-Hyun Kim Department of Marine Science and Convergence Technology Hanyang University Ansan Korea Korea Polar Research Institute 26 Songdomirae-ro Yeonsugu Incheon Korea

We investigated the occurrence and distribution of terrestrial-derived hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system and their potential impact on the application of the ring index of OH-GDGTs(RI-OH) as a sea surface temperature(SST) proxy in the eastern Yellow Sea. Thereby, we analyzed various samples collected along the Han River and from its surrounding areas(South Korea, n = 34). The OHGDGTs were found in all samples investigated. OH-GDGT-0 was the dominant OH-GDGT component in the estuary and marine samples while OH-GDGT-2 was generally dominant in the soils, the lake sediments and the river suspended particulate matter(SPM). Our results thus suggests a possible warm bias of the RI-OH-derived summer SSTs in the coastal zone to which a large amount of terrestrial organic matter is being supplied. Further studies are necessary to better assess the applicability of the RI-OH proxy in the eastern Yellow Sea.

关键词： Hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) Sea surface temperature(SST) Han river Yellow Sea

Generation of Accelerated Stability Experiment Profile of Inertial Platform Based on Finite Element

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2012年第4期25卷 584-592页

作者： chen Yunxia HUANG Xiaokai kang Rui School of Reliability and System Engineering Beihang UniversityBeijing 100191China

The residual stress generated in the manufacturing process of inertial platform causes the drift of inertial platform parameters in long-term storage ***,the existing temperature cycling experiment could not meet the increased repeatability technical requirements of inertial platform *** order to solve this problem,in this paper,firstly the Unigraphics（UG） software and the interface compatibility of ANSYS software are used to establish the inertial platform finite element ***,the residual stress is loaded into finite element model by ANSYS function editor in the form of surface loads to analyze the *** then,the generation based on ANSYS simulation inertial platform to accelerate the stability of experiment profile is achieved by the application of the analysis method of orthogonal experimental design and ANSYS thermal-structural *** optimum accelerated stability experiment profile is determined finally,which realizes the rapid,effective release of inertial platform residual *** research methodology and conclusion of this paper have great theoretical and practical significance to the production technology of inertial platform.

关键词： inertial platform residual stresses accelerated stability orthogonal experimental design ANSYS thermal-structural coupled analysis

Validation methodology for distribution-based degradation model

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2012年第4期23卷 553-559页

作者： Yunxia chen Zhiguo Zeng Rui kang School of Reliability and Systems Engineering Beihang UniversityBeijing 100191E R.China

Distribution-based degradation models （or graphical approach in some literature） occur in a wide range of applications. However, few of existing methods have taken the validation of the built model into consideration. A validation methodology for distribution-based models is proposed in this paper. Since the model can be expressed as consisting of assumptions of model structures and embedded model parameters, the proposed methodology carries out the validation from these two aspects. By using appropriate statistical techniques, the rationality of degradation distributions, suitability of fitted models and validity of degradation models are validated respectively. A new statistical technique based on control limits is also proposed, which can be implemented in the validation of degradation models＇ validity. The case study on degradation modeling of an actual accelerometer shows that the proposed methodology is an effective solution to the validation problem of distribution-based de qradation models.

关键词： degradation model distribution-based degradationmodel graphical method model validation control limits.

High Mg# of the continental crust explained by calc-alkaline differentiation

在线全文

学校读者我要写书评

暂无评论

National Science Review 2023年第3期10卷 92-99页

作者： Ming Tang Xuanyu Liu kang chen Key Laboratory of Orogenic Belt and Crustal Evolution Ministry of Education School of Earth and Space Sciences Peking University State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

We used compiled geochemical data to investigate the mechanisms that control Mg#(molar ratio of Mg/(Mg+FeT)) in andesitic arc *** find that andesites from mature continental arcs with crustal thickness of>45 km have systematically higher Mg# than those from oceanic arcs with crustal thickness of<30 *** elevated Mg# in continental arc lavas results from strong Fe depletion during high-pressure differentiation favored in thick *** proposal is reinforced by our compiled melting/crystallization experiment *** show that the Mg# characteristics of continental arc lavas match that of the continental *** findings suggest that the formation of many high-Mg#andesites and the continental crust may not require slab-melt/peridotite ***,the high Mg# of the continental crust can be explained by intracrustal calc-alkaline differentiation processes in magmatic orogens.

关键词： high-Mg# andesite calc-alkaline differentiation Fe depletion slab melting continental crust

Coupling behavior between adhesive and abrasive wear mechanism of aero-hydraulic spool valves

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2016年第4期29卷 1119-1131页

作者： chen Yunxia Gong Wenjun kang Rui School of Reliability and Systems Engineering Beihang University

Leakage due to wear is one of the main failure modes of aero-hydraulic spool valves. This paper established a practical coupling wear model for aero-hydraulic spool valves based on dynamic system modelling theory. Firstly, the experiment for wear mechanism verification proved that adhesive wear and abrasive wear did coexist during the working process of spool valves. Secondly coupling behavior of each wear mechanism was characterized by analyzing actual time-variation of model parameters during wear evolution process. Meanwhile, Archard model and three-body abrasive wear model were utilized for adhesive wear and abrasive wear, respectively. Furthermore, their coupling wear model was established by calculating the actual wear volume. Finally, from the result of formal test, all the required parameters for our model were obtained. The relative error between model prediction and data of pre-test was also presented to verify the accuracy of model, which demonstrated that our model was useful for providing accurate prediction of spool valve's wear life. (C) 2016 The Authors. Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.

关键词： Abrasive wear Adhesive wear Aero-hydraulic spool valves Coupling effects Dynamic model

Dynamical model of encapsulated gas microbubble under ultrasound based on elastic mechanics

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2017年第7期60卷 60-69页

作者： kang chen JiangTao Feng KaiYu Xu Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China College of Sciences Shanghai University Shanghai 200444 China

Based on the theory of elastic mechanics, a dynamical model of an encapsulated gas microbubble under ultrasound is *** dynamical motion of the microbubble is divided into three states: buckled, elastic, and ruptured. The model describes the compression-only behavior appropriately and derives the transient variation of the resonance frequency of the damped oscillation and the relation between the critical rupture radius and initial outer radius. The normal stress in the tangential direction plays the principal role in the rupture and buckling of the encapsulating shell, resulting in likely rupture for a larger microbubble and resistance to rupture for a thicker-shell microbubble. Comparison of proposed dynamical model with Marmottant's model has been given. The dynamical model can be employed in ultrasound medical diagnostics and therapy of drug incorporation or extravasation through further understanding the influence of the encapsulating shell.

关键词： dynamical model encapsulated gas microbubble ultrasound buckle rupture

High-efficiency technique based on dielectrophoresis for assembling metal,semiconductor,and polymer nanorods

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第5期12卷 368-373页

作者： Heng YUAN Kyu-jin KIM Won-seok kang Byoung-ho kang Se-hyuk YEOM Jae-ho KIM shin-won kang School of Electrical Engineering and Computer Science Kyungpook National University 1370 Sankyuk-dong Bukgu Daegu 702-701 Korea) Department of Molecular Science and Technology Ajou University San s.Woncheon-dongYeongtong-guSuwon 443-749Korea School of Electronic Engineering College oflT Engineering Kyungpook National University 13 70 Sankyuk-dong Bukgu Daegu 702-701 Korea

This paper presents a high-efficiency technique based on dielectrophoresis (DEP) for assembling metal, semiconductor, and polymer nanorods, which are synthesized by electrochemical deposition (ECD). The assembly patterns of these nanorods (width: 20 nm; length: 7 μm) were designed using a finite element method (FEM) simulation tool. Further, these nanorods were used in our experiment after their assembly patterns were fabricated. The assembly yield was found to be approximately 70% at an AC voltage of 30 Vp-p and at frequencies of 20 and 30 kHz, and the DC voltage prevented the random alignment of the nanorods at the edge of the assembly pattern. Moreover, the above-mentioned nanorods, which had different permittivities, were found to have similar assembly yields. The proposed method can be improved and applied to nanostructure device fabrication.

关键词： Nanorod Assembly Dielectrophoresis (DEP) Finite element method (FEM) Electrochemical deposition (ECD) method

Numerical characterization of heat transfer in closed-loop vertical ground heat exchanger

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第1期53卷 111-116页

作者： Chulho LEE Hujeong GIL Hangseok CHOI shin-Hyung kang School of Civil Environmental and Architectural EngineeringKorea University5-GaAnam-DongSeongbuk-GuSeoul 136-713Republic of Korea Pyungsan SI Co. Ltd.1337-31 Seocho-DongSeocho-GuSeoul 137-860Republic of Korea Department of Mechanical Engineering Konyang University119Deahak-RoNonsanChungnam 320-711Republic of Korea

A series of numerical analyses has been performed on the characteristics of heat transfer in a closed-loop vertical ground heat exchanger(U-loop).A 2-D finite element analysis was conducted to evaluate the temperature distribution over the cross section of the U-loop system involving high-density polyethylene(HDPE) pipe/grout/soil to compare the sectional efficiency between the conventional U-loop and a new latticed HDPE pipe system,which is equipped with a thermally insulating lattice in order to reduce thermal interference between the inlet and outlet *** addition,a 3-D finite volume analysis(FLUENT) was adopted to simulate the operation of the closed-loop vertical ground heat exchanger with the consideration of the effect of a distance between the inlet and outlet pipes,grout's thermal properties,the effectiveness of the latticed HDPE pipe system,and the rate of circulation *** was observed that the thermal interference between the two strands of U-loop is of importance in enhancing efficiency of the ground heat ***,it is recommended to modify the configuration of the conventional U-loop system by equipping the thermally insulating lattice between the two pipe strands.

关键词： ground heat exchanger HDPE pipe latticed pipe sectional efficiency

Numerical Simulation of Macrosegregation Caused by Thermal–Solutal Convection and Solidification Shrinkage Using ALE Model

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2019年第11期32卷 1396-1406页

作者： kang-Xin chen Hou-Fa Shen Key Laboratory for Advanced Materials Processing Technology Ministry of Education School of Materials Science and Engineering Tsinghua University

Solidifi cation shrinkage has been recognized as an important factor for macrosegregation formation. An arbitrary Lagrangian–Eulerian(ALE) model is constructed to predict the macrosegregation caused by thermal–solutal convection and solidi-fi cation shrinkage. A novel mesh update algorithm is developed to account for the domain change induced by solidifi cation shrinkage. The velocity–pressure coupling between the non-homogenous mass conservation equation and momentum equation is addressed by a modifi ed pressure correction method. The governing equations are solved by the streamline-upwind/Petrov–Galerkin-stabilized fi nite element algorithm. The application of the model to the Pb-19.2 wt%Sn alloy solidifi cation problem is considered. The inverse segregation is successfully predicted, and reasonable agreement with the literature results is obtained. Thus, the ALE model is established to be a highly effective tool for predicting the macrosegregation caused by solidifi cation shrinkage and thermal–solutal convection. Finally, the effect of solidifi cation shrinkage is analyzed. The results demonstrate that solidifi cation shrinkage delays the advance of the solidifi cation front and intensifi es the segregation.

关键词： Macrosegregation Solidification shrinkage Finite element method Arbitrary Lagrangian–Eulerian(ALE)

Using PoF models to predict system reliability considering failure collaboration

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2016年第5期29卷 1294-1301页

作者： Zeng Zhiguo kang Rui chen Yunxia Chair on Systems Science and Energetic Challenge Fondation Electricitéde France (EDF) Centrale Supélec Université Paris-Saclay School of Reliability and Systems Engineering Beihang University

Existing Physics-of-Failure-based （PoF-based） system reliability prediction methods are grounded on the independence assumption, which overlooks the dependency among the compo- nents. In this paper, a new type of dependency, referred to as failure collaboration, is introduced and considered in reliability predictions. A PoF-based model is developed to describe the failure behavior of systems subject to failure collaboration. Based on the developed model, the Bisection-based Reliability Analysis Method （BRAM） is exploited to calculate the system reliability. The developed methods are applied to predicting the reliability of a Hydraulic Servo Actuator （HSA）. The results demonstrate that the developed methods outperform the traditional PoF-based reliability prediction methods when applied to systems subject to failure collaboration.

关键词： Dependency Failure collaboration Physics-of-failure Reliability modeling Reliability prediction