检索结果-南通市图书馆

Research on the iterative method for model updating based on the frequency response function

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第2期28卷 450-457页

作者： Wei-Ming Li jia-zhen Hong Department of Engineering Mechanics Shanghai Jiaotong University200240 ShanghaiChina

Model reduction technique is usually employed in model updating process. In this paper, a new model updat- ing method named as cross-model cross-frequency response function （CMCF） method is proposed and a new iterative method associating the model updating method with the mo- del reduction technique is investigated. The new model up- dating method utilizes the frequency response function to avoid the modal analysis process and it does not need to pair or scale the measured and the analytical frequency re- sponse function, which could greatly increase the number of the equations and the updating parameters. Based on the traditional iterative method, a correction term related to the errors resulting from the replacement of the reduction ma- trix of the experimental model with that of the finite element model is added in the new iterative method. Comparisons be- tween the traditional iterative method and the proposed itera- tive method are shown by model updating examples of solar panels, and both of these two iterative methods combine the CMCF method and the succession-level approximate reduc- tion technique. Results show the effectiveness of the CMCF method and the proposed iterative method .

关键词： Model updating Model reduction Frequency response function Iteration

Reversibly photochromic wood constructed by depositing microencapsulated/polydimethylsiloxane composite coating

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2022年第4期33卷 1409-1418页

作者： zhen jia Wenhui Bao Chengyun Tao Wenlong Song School of Mechanical and Electrical Engineering Northeast Forestry UniversityHarbin 150040People’s Republic of China School of Civil Engineering Harbin UniversityHarbin 150086People’s Republic of China

Photochromic wood was fabricated by coating microencapsulated photochromic material(MP)/polydimethylsiloxane composites onto wood using a simple drop-coating ***-melamine–formaldehyde resin was used to microencapsulate the photochromic material(PM)via in situ *** concentration of the MP affected the photochromic property of the wood *** total color change(ΔE*)reached 82.2 when the concentration of the composite coating is 8%.Adhesion tests confirmed that the composite coating adhered firmly to the *** method is potentially useful for the production of functional wooden products,such as anti-counterfeiting materials and aesthetic wood.

关键词： Wood Photochromism Microencapsulation Urea-melamine–formaldehyde resin Drop-coating method

ADDITIONAL PRESSURE LOSSES OF SOLID-LIQUID FLOW IN AN OSCILLATING PIPELINE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2002年第1期14卷 75-80页

作者： Xia, jian-Xin Huang, jia-zhen Cent. of Environ. Sci. Peking Univ. Beijing 100871 China

Manganese nodules on the ocean bed become attractive mineral resources because of its huge commercial benefits. In the last decades, a set of hydraulic lifting system with pipeline has been developed to mining these particles. It is inevitable that lifting pipe will oscillate due to its operation and the motion properties of the solid in the two-phase flow will be changed because of the oscillating of pipe-line. The pressure gradient along the lifting pipeline was investigated with a series of experiments. At the same time, a new pressure drop prediction method on the basis of Lagrange simulation technique was worked out by use of an axial momentum balance and this method provides a way to predict the pressure loss of solid-liquid mixture. The results show that compared with the fixed pipe transportation, the pressure gradient of the oscillating pipe is greater than that of the fixed pipe because of the collision and unsteady friction between particles and the pipe wall due to the oscillating motion of the pipe. Moreover, it is found that the prediction results are in good agreement with those of the experiments.

关键词： Two phase flow Underwater mineral resources

An efficient formulation based on the Lagrangian method for contact–impact analysis of flexible multi-body system

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2016年第2期32卷 326-334页

作者： Peng Chen Jin-Yang Liu jia-zhen Hong Department of Engineering Mechanics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiaotong University

In this paper,an efficien formulation based on the Lagrangian method is presented to investigate the contact–impact problems of f exible multi-body ***,the penalty method and the Hertz contact law are the most commonly used methods in engineering ***,these methods are highly dependent on various non-physical parameters,which have great effects on the simulation ***,a tremendous number of degrees of freedom in the contact–impact problems will influenc thenumericalefficien *** of these two problems,a formulation combining the component mode synthesis method and the Lagrangian method is presented to investigate the contact–impact problems in fl xible multi-body system ***,the finit element meshing laws of the contact bodies will be studied preliminarily.A numerical example with experimental verificatio will certify the reliability of the presented formulationincontact–***,aseries of numerical investigations explain how great the influenc of the finit element meshing has on the simulation *** the limitations of the element size in different regions are summarized to satisfy both the accuracy and efficien y.

关键词： Multi-body dynamics Contact–impact analysis Lagrangian method Component mode synthesis

Contact-impact formulation for multi-body systems using component mode synthesis

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第3期29卷 437-442页

作者： Peng Chen Jin-Yang Liu jia-zhen Hong Department of Engineering Mechanics School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University

The efficiency and accuracy are two most concerned issues in the modeling and simulation of multi-body systems involving contact and impact. This paper proposed a formulation based on the component mode synthesis method for planar contact problems of flexible multi-body systems. A flexible body is divided into two parts： a contact zone and an un-contact zone. For the un-contact zone, by using the fixed-interface substructure method as reference, a few low-order modal coordinates are used to replace the nodal coordinates of the nodes, and meanwhile, the nodal coordinates of the local impact region are kept unchanged, therefore the total degrees of freedom （DOFs） are greatly cut down and the computational cost of the simulation is significantly reduced. By using additional constraint method, the impact constraint equations and kinematic constraint equations are derived, and the Lagrange equations of the first kind of flexible multi-body system are obtained. The impact of an elastic beam with a fixed half disk is simulated to verify the efficiency and accuracy of this method.

关键词： Contact-impact analysis · Flexible multi-body system · Component mode synthesis

The Standard Association Constant of Ion Pair [GaCl]^(2+)in the System of HCl+GaCl_3+H_2O

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2002年第5期13卷 442-443页

作者： jia zhen YANG Ru Bo ZHANG Institute of Rare Scattered Element Chemistry Liaoning UniversityShenyang 110036

The standard association constants of ionic pair [GaCl]2+, Kas, were determined by emf(electromotive force) method at 278.15 to 318.15 K. The thermodynamic quantities for the ionic association process were calculated... 详细信息

关键词： Ion pair association entropy EMF GaCl3.

Crown ether-assisted room-temperature halide passivation for highefficiency PbS quantum dots enabling large-area and long-lifetime near-infrared QD-OLEDs

在线全文

学校读者我要写书评

暂无评论

Nano Research 2023年第5期16卷 7537-7544页

作者： zhen jia Haoyun Shao Jingyi Xu Yu Dai Juan Qiao Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of ChemistryTsinghua UniversityBeijing 100084China Laboratory for Flexible Electronics Technology Tsinghua UniversityBeijing 100084China

High-efficiency and low-cost near-infrared(NIR)emitting quantum dots(QDs)are highly desirable for next-generation intrinsically flexible NIR light *** passivation is commonly employed to passivate surface traps to obtain high-quality NIRemitting PbS QDs,but this procedure requires high temperature and inert *** we develop a facile roomtemperature halide passivation method for highly efficient NIR-emitting PbS QDs by employing crown ethers as a unique auxiliary *** and theoretical investigations reveal that the formation of K^(+)-crown ethers complex effectively facilitates the dissociation of KCl in toluene and releases more Cl^(−)ions for extraordinary halide passivation at room temperature and in the air,thus improving the photoluminescence quantum yield from 24%to 35%in solution and further to 44%in blend *** well-passivated PbS QD films are integrated with red organic light-emitting diodes(OLEDs)and the resulting QDOLEDs exhibit high-performance NIR emission centered at 887 nm,a high external quantum efficiency of 5.2%at a radiance of 10 W·sr^(−1)·m^(−2),superior operational stability with long lifetime T90 of 188 h at the current density of 25 mA·cm^(−2).We also construct a large-area NIR QD-OLED(5 cm×5 cm)with desirable uniform *** work opens a new avenue to achieve robust large-area NIR planar light sources for broad applications.

关键词： near-infrared emission PbS quantum dot chloride surface passivation crown ether light-emitting diode

Efficacy of iontophoresis-assisted epithelium-on corneal cross-linking for keratoconus

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

International Journal of Ophthalmology(English edition) 2018年第4期11卷 687-694页

作者： Hong-zhen jia Xiu-Jun Peng Department of Ophthalmology Chinese PLA Navy General Hospital

Corneal cross-linking（CXL） is a noninvasive therapeutic procedure for keratoconus that is aimed at improving corneal biomechanical properties by induction of covalent cross-links between stromal proteins. It is accomplished by ultraviolet A（UVA） radiation of the cornea, which is first saturated with photosensitizing riboflavin. It has been shown that standard epithelium-off CXL（S-CXL） is efficacious, and it has been recommended as the standard of care procedure for keratoconus. However, epithelial removal leads to pain, transient vision loss, and a higher risk of corneal infection. To avoid these disadvantages, transepithelial CXL was developed. Recently, iontophoresis has been adopted to increase riboflavin penetration through the epithelium. Several clinical observations have demonstrated the safety and efficacy of iontophoresisassisted epithelium-on CXL（I-CXL） for keratoconus. This review aimed to provide a comprehensive summary of the published studies regarding I-CXL and a comparison between I-CXL and S-CXL. All articles used in this review were mainly retrieved from the Pub Med database. Original articles and reviews were selected if they were related to the I-CXL technique or related to the comparison between I-CXL and S-CXL.

关键词： corneal cross-linking keratoconus iontophoresis riboflavin ultraviolet A

Selective dissolution of eodiagenesis cements and its impact on the quality evolution of reservoirs in the Xing＇anling Group,Suderte Oil Field, Hailar Basin, China

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

Petroleum Science 2016年第3期13卷 402-417页

作者： zhen-zhen jia Cheng-Yan Lin Li-Hua Ren Chun-Mei Dong School of Geosciences China University of Petroleum Qingdao 266580 Shandong China Key Laboratory of Reservoir Geology in Shandong Province Qingdao 266580 Shandong China

Reservoirs in the Xing＇anling Group in the Suderte Oil Field,Hailar Basin exhibit ultra-low to low permeability and high tuffaceous material *** study comprehensively analyzed diagenesis and quality evolution of these low-permeability reservoirs using thin sections,SEM samples,rock physical properties,pore water data,as well as geochemical numerical *** and analcite are the two main types of cements precipitated in the eodiagenetic stage at shallow burial depths in the *** two cements occupied significant primary intergranular pores and effectively retarded deep burial *** textures suggest selective dissolution of massive analcite and little dissolution of calcite in the mesodiagenetic *** calculations utilizing the Geochemist＇s Workbench 9.0indicated that the equilibrium constant of the calcite leaching reaction is significantly smaller than that of the analcite leaching reaction,resulting in extensive dissolution of analcite rather than calcite in the geochemical system with both minerals *** simulations with constraints of kinetics and pore water chemistry demonstrated that the pore water in the Xing＇anling group is saturated with respect to calcite,but undersaturated with analcite,leading to dissolution of large amounts of analcite and no dissolution of *** secondary intergranular pores have formed in analcite-cemented reservoirs from selective dissolution of analcite in the mesodiagenetic stage;the analcite dissolution formed preferential flow paths in the reservoirs,which promoted feldspar dissolution;and dissolution of such minerals led to the present reservoirs with medium porosity and low ***-cemented tight reservoirs have not experienced extensive dissolution of cements,so they exhibit ultra-low porosity and permeability.

关键词： Eodiagenetic cements Calcite Analcite Selective dissolution Secondary porosity Hailar Basin