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The influence of agglomerates on the densification and microstructural evolution in sintering of a multi-particle system

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Science China(Physics,Mechanics & Astronomy) 2012年第6期55卷 1051-1058页

作者： WANG Chao chen shaohua The State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Effects of agglomerates on the densification behavior and microstructural evolution during solid-state sintering of a cube of copper particles have been studied with discrete element method (DEM).It is found that the densification of the sintering system decreases as the volume fraction of agglomerates *** a given volume fraction of agglomerates,the smaller the size of agglomerates,the poorer the densification and more inhomogeneous the compact *** morphology and distribution of agglomerates have negligible effects on the densification,especially for the case with a low volume fraction of *** with a smaller average coordination number would have more restriction on the densification of sintering *** our best knowledge,it is the first time to study the effect of agglomerates on sintering behavior using *** study should be useful for further investigations of the effect of various inhomogeneities of microstructure on the complex sintering process by DEM.

关键词： solid-state sintering discrete element method agglomerate microstructure evolution

Landfill leachate treatment by MBR: Performance and molecular weight distribution of organic contaminant

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Chinese Science Bulletin 2006年第23期51卷 2831-2838页

作者： chen shaohua LIU Junxin Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

A membrane bioreactor (MBR) with an air-lift bioreactor and gravity flow is applied to treating landfill leachate. More than 99% of BOD5 (biochemical oxygen demand for five days) removal effi-ciency is achieved with less than 35 mg/L of BOD_5 in the effluent at less than 1.71 kg BOD5/m^3·d of BOD_5 loading rate. When DO (dissolved oxygen) is maintained at the range of 2.3―2.8 mg/L and the loading rate of NH_4^+-N (ammonium nitrogen) is kept at 0.16― 0.24 kg NH_4^+-N/m^3·d, the NH_4^+-N in the effluent is less than 15 mg/L. However, compared with high removal rates of BOD_5 and NH_4^+-N, the removal effi-ciency of soluble chemical oxygen demand (SCOD) varies between 70% and 96%. The investigation of molecular weight (MW) distribution has been carried out by the gel permeation chromatography (GPC) so as to understand the fate of organic matters in the MBR treating of landfill leachate. Results indicate that organic matters of the landfill leachate are composed of a high MW fraction (MW of the peak, MWp = 11480―13182 Da) and a low MW fraction (MWp = 158―275 Da). The high MW fraction is not biode-gradable, but can be decreased with microfiltration membrane. The most of the low MW fraction is bio-degradable, but the residue of the low MW fraction is able to permeate through the membrane, thus re-sulting in high SCOD in the effluent of the MBR.

关键词：垃圾沥出液隔膜生物反应器分子权重分布废水处理

Horizontal Slow Oscillation of a Moored Tanker and Numerical Method of Hopf-Bifurcation

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China Ocean Engineering 1993年第4期8卷 383-400页

作者： chen, shaohua Sun, Mingguang Zhongshan Univ Guangzhou China

In this paper, a six-order nonlinear dynamic model with three degrees of freedom is presented for the study of the 'fishtail' motion of a Single Point Mooring System. The effect of parameter variations on the equilibrium state of the system is analyzed. In order to study the stability of the equilibrium state, the mooring-line length l is chosen as a bifurcation parameter, so that all eigenvalues of the Jacobian matrix under different parameters can be worked out, and then the Hopf-bifurcation point can be found. Finally, the Hopf-bifurcation periodic solution of the system is computed.

关键词： Degrees of freedom (mechanics) Eigenvalues and eigenfunctions Mathematical models Matrix algebra Numerical methods Oscillations System stability Tankers (ships)

Interfacial behavior of a thermoelectric film bonded to a graded substrate

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Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1853-1870页

作者： Juan PENG Dengke LI Zaixing HUANG Guangjian PENG Peijian chen shaohua chen School of Materials Science and Physics State Key Laboratory for Geomechanics and Deep Underground EngineeringSchool of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou 221116Jiangsu ProvinceChina State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310014China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and Structures Beijing Institute of TechnologyBeijing 100081China Collaborative Innovation Center of Electric Vehicles in Beijing Beijing Institute of TechnologyBeijing 100081China

To improve the thermoelectric converting performance in applications such as power generation,reutilization of heat energy,refrigeration,and ultrasensitive sensors in scramjet engines,a thermoelectric film/substrate system is widely designed and applied,whose interfacial behavior dominates the strength and service life of thermoelectric ***,a theoretical model of a thermoelectric film bonded to a graded substrate is *** interfacial shear stress,the normal stress in the thermoelectric film,and the stress intensity factors affected by various material and geometric parameters are comprehensively *** is found that adjusting the inhomogeneity parameter of the graded substrate,thermal conductivity,and current density of the thermoelectric film can reduce the risk of interfacial failure of the thermoelectric film/graded substrate *** a stiffer and thicker thermoelectric film is advantageous to the reliability of the thermoelectric film/graded substrate *** results should be of great guiding significance for the present and upcoming applications of thermoelectric materials in various fields.

关键词： thermoelectric film graded substrate interfacial behavior singular integral equation shear stress intensity factor

Dispersive behavior of high frequency Rayleigh waves propagating on an elastic half space

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Acta Mechanica Sinica 2021年第4期37卷 562-569,I0001页

作者： Ning Jia Zhilong Peng Jianjun Li Yin Yao shaohua chen Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-Functional Composite Materials and Structures Beijing Institute of TechnologyBeijing 100081China School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China

When the wavelength of Rayleigh wave is comparable with nanometers,Rayleigh wave will become *** an interesting phenomenon cannot be predicted by the classical theory of *** order to reveal the internal mechanism and influencing factors of the dispersion,a model of Rayleigh wave propagating on an elastic half space is established and analyzed by a new theory of surface elastodynamics,in which the surface effect characterized by both the surface energy density and surface inertia is *** intrinsic nano-length scales,including the ratio of bulk surface energy density to bulk shear modulus and the ratio of surface mass density to bulk mass density,are *** is found that when the wavelength of Rayleigh wave is comparable with the two intrinsic nano-lengths,the surface effect becomes *** a result,dispersion of Rayleigh wave happens and even two Rayleigh waves with different wave speeds may ***,it is found that the effect of surface energy density would enhance the wave speed,while that of surface inertia would reduce *** the increase of wavelength,both effects gradually disappear and the Rayleigh wave speed degenerates to the classical *** results of this paper are not only helpful to understand the dispersive mechanism of elastic waves,but also helpful for the fine design and measurement of nanowave devices.

关键词： Rayleigh wave High frequency Dispersion Elastodynamics Surface effect

Hierarchically porous zeolites synthesized with carbon materials as templates

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Frontiers of Chemical Science and Engineering 2021年第6期15卷 1444-1461页

作者： Huan Wang Guo Du Jiaqing Jia shaohua chen Zhipeng Su Rui chen Tiehong chen Institute of New Catalytic Materials Science School of Materials Science and EngineeringKey Laboratory of Advanced Energy Materials Chemistry(MOE)Nankai UniversityTianjin300350China

Hierarchically porous zeolites are promising candidates in catalytic conversion of relatively bulky molecules,and their syntheses have attracted significant *** both industrial and scientific perspectives,different carbon materials have been widely employed as hard templates for the preparation of hierarchically porous zeolites during the past two *** this review,the progress in synthetic strategies using carbon materials as templates is comprehensively *** on the affinity between the carbon templates and zeolite precursors,the substantial strategies for synthesizing hierarchical zeolites are introduced in direct templates and indirect *** templates methods,by which the carbon materials are directly mixed with precursors gel as hard templates,are first ***,we discuss the indirect templates method(crystallization of carbon-silica composites),by which the carbon is produced by in situ pyrolysis of organic-inorganic *** addition,the technique of encapsulating metal species into zeolites crystals with the assistance of carbon templates is also *** the conclusion part,the factors affecting the synthesis of carbon-templated hierarchically porous zeolites are *** review is expected to attract interest in the synthesis strategies of hierarchically porous zeolites,especially cost-effective and large-scale production methodologies,which are essential to the industrial application of hierarchical zeolites.

关键词： hierarchical zeolites carbon materials direct templates indirect templates carbon-silica composites

Occurrence of veterinary antibiotics in struvite recovery from swine wastewater by using a fluidized bed

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Frontiers of Environmental Science & Engineering 2018年第3期12卷 99-105页

作者： Zhi-Long Ye Yujun Deng Yaoyin Lou Xin Ye shaohua chen Key Laboratory of Urban Pollutant Conversion Institute of Urban Environment Chinese Academy of Sciences Xiarnen 361021 China

Recovering phosphorus from livestock wastewater has gained extensive attention. The residue of veterinary antibiotics in the wastewater may be present in the recovered products, thereby posing pharmacological threats to the agricultural planting and human health. This study investigated antibiotic occurrence in the struvite particles recovered from swine wastewater by using a fluidized bed. Results revealed that tetracyclines possessed significant residues in the struvite granules, with the values ranging from 195.2μ***^-1 to 1995.0 μ***^-1. As for fluoroquinolones, their concentrations varied from 0.4μg·kg^-1 to 1104.0 μg·kg^-1. Struvite particles were of various sizes and. shapes and displayed different antibiotic adsorption capacities. The data also showed that the smaller granules contained much more antibiotics than the larger ones, indicating that the fluidized granulation process of struvite crystals plays an important role on the accumulation of antibiotics. For tetracyclines, organic matters and struvite adsorption exerted significant impacts on tetracyclines migration. The outcomes underscore the need to consider the residues of antibiotics in resource recovery from wastewater because they exert pharmacological impacts on the utilization of recovered products.

关键词： Antibiotic Struvite Phosphorus recovery Swine wastewater Fluidized bed

Selection of cost-effective magnesium sources for fluidized struvite crystallization

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Journal of Environmental Sciences 2018年第8期30卷 144-153页

作者： Jinsong Wang Xin Ye Zhaoji Zhang Zhi-Long Ye shaohua chen Key Laboratory of Urban Environment and Health Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Struvite crystallization has been considered a promising approach to recover phosphorus from wastewater. However, its practical application is limited, probably because of the high cost of magnesium（Mg）. In this study, a comprehensive economic analysis was conducted using five Mg sources（MgCl2, MgSO4, MgO, Mg（OH）2, and bittern） during the operation of a pilot-scale fluidized bed reactor（FBR）, using swine wastewater as the case matrix. First, the economic operating conditions were investigated, and subsequently, the performance and the costs of the five Mg sources were compared. The results indicated that the FBR could be operated most economically at pH of 8.5 and Mg to phosphorus（Mg/P） molar ratio of 1.5. Under these conditions, no significant differences in phosphorus removal and product quality could be found between the five Mg sources. Selecting the most economical Mg source was thus highly dependent on the prices of the reagents and Mg sources. Low-solubility Mg sources were preferable when NaOH was priced higher, while high-solubility Mg sources proved more economical when HNO3 was expensive. The bittern was the most economical choice only when the distances for total inorganic orthophosphate removal and struvite recovery were shorter than 40 and 270 km, respectively. The current study provides an overview of the economic selection of an Mg source, which can help reduce the cost of struvite crystallization.

关键词： Struvite Fluidized bed reactor Magnesium source Economy Phosphorus recovery

Research on fault diagnosis of a railway point machine based on a multi-entropy feature extraction method and support vector machine

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Transportation Safety and Environment 2023年第4期5卷 58-66页

作者： Yunting Zheng shaohua chen Zhiyong Tan Yongkui Sun Automation and Electrical Engineering College Dalian Jiaotong UniversityDalian 116028LiaoningChina CRRC Dalian Co.Ltd. Dalian 116021LiaoningChina National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong UniversityBeijing 100044China

A new fault diagnosis method is proposed to effectively extract the fault features of the sound signal of typical faults of ZDJ9 railway point machines.A multi-entropy feature extraction method is proposed by combing multi-scale permutation entropy and wavelet packet ***,empirical mode decomposition is performed on sound signals to obtain modal components with different time ***,multi-scale permutation entropy is extracted from these ***,the wavelet packet entropy of the sound signals of these sensitive nodes is obtained by analysing the reconstructed signals of the last layer *** the multi-scale permutation entropy and the wavelet packet entropy can distinguish the subtle features of the signal,the subtle features of the information among the high-dimensional features,ReliefF is ***,a support vector machine(SVM)is used to judge the original sismal can be obtained as the feature vector of the 2DJ9 iway point mnchine in ditterent states,To reduce the redundant fault type of a ZDJ9 rilway point machine.

关键词： railway point machine fault diagnosis sound signal support vector machine(SVM)

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