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Chinese Journal of Mechanical Engineering 2000年第4期13卷 318-324页

作者： Zhu Qin yi xuemei (School of Mechanical Engineering，Shanghai University) 上海大学上海

A model for the non-linear axial vibrations of the hydrodynamic thrust bearing-rotor system in a turboexpander is described. The axial transient process of the system is investigated. The time-dependent form ofthe Reynolds equation is solved by a finite difference method with successive overrelaxation scheme to obtain the hydrodynamic forces of the sector-shaped thrust bearing (SSTB). Using these forces, the equation of motion is solved by the fourth-order Runge-Kutta method and the Adams method to predict the transient behaviour of the thrust bearing-rotor system (TBRS).Also,the linearized stiffness and damping coefficients of the oil film hydrodynamic SSTB are *** analyses of the axial transient response of the system under both linear and non-linear conditions are performed. The non-linearity of oil film forces can significantly contribute to the axial transient response. Conclusions obtained can be applied for evaluation of the reliability of the TBRS.

关键词： Axial transient response Thrust bearing-rotor system Turboexpander

INVESTIGATION ON THE APPLICATION OF THE BOUNDARY ELEMENT METHOD TO THE SPILL GROOVED THRUST BEARING

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Chinese Journal of Mechanical Engineering 2000年第2期13卷 81-89页

作者： Zhu Qin yi xuemei (School of Mechanical Engineering, Shanghai University) 上海大学上海

An application of the boundary element method (BEM) is presented to calculate the behaviors of a spiral grooved thrust bearing (SGTB). The basic reason is that the SGTB has very complex boundary conditions that can hinder the effective or sufficient applications of the finite difference method (FDM) and the finite element method (FEM), despite some existing work based on the FDM and the FEM. In other to apply the BEM, the pressure control equation, i. e., Reynolds' equation, is first transformed into Laplace's and Poisson's form of the equations. Discretization of the SGTB with a set of boundary elements is thus explained in detail, which also includes the handling of boundary conditions. The Archimedean SGTB is chosen as an example of the application Of BEM, and the relationship between the behaviors and structure parameters of the bearing are found and discussed through this calculation. The obtained results lay a solid foundation for a further work of the design of the SGTB.

关键词： Pressure control equation Boundary element method Spiral grooved thrust bearing

Systematic and long-term technical validity of toxicity determination and early warning of heavy metal pollution based on an automatic water-toxicity-determination-system

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Frontiers of Environmental Science & Engineering 2024年第8期18卷 59-71页

作者： Yue yi Baoguo Wang xuemei yi Fan Zha Haisen Lin Zhijun Zhou Yanhong Ge Hong Liu School of Life Science Beijing Institute of TechnologyBeijing 100081China Institute of Environmental Biology and Life Support Technology School of Biological Science and Medical EngineeringBeihang UniversityBeijing 100191China Infore Environment Technology Group Foshan 528000China Jiangmen Ecological Environment Monitoring Station Jiangmen 529000China Guangzhou Sub-branch of Guangdong Ecological and Environmental Monitoring Center Guangzhou 510000China

Water toxicity determination with electrochemically active bacteria(EAB)shows promise for providing early warnings for heavy metal pollution in ***,thus far,only idealized tests with a few types of heavy metals have been *** this study,an automatic water-toxicitydetermination system with high technical maturity was established,and the toxicological properties of common heavy metals were systematically *** results demonstrated that the common heavy metals linearly inhibited EAB currents in the range of 0.1 mg/L to 0.5 mg/*** toxicity ranking of the tested heavy metals was Pb^(2+)>Tl^(3+)>Cu^(2+)>Cd^(2+)>Zn^(2+)>Ni^(2+)>Hg^(2+)>As^(3+).The toxicity interaction mainly exhibited an antagonistic effect in binary heavy metal *** system can accurately determine surface water toxicity and rapidly monitor heavy metal pollution,with good repeatability and a long ***,this study demonstrates that EAB are capable of long-term(>60 d)surface water quality monitoring and on-site early warning of heavy metal pollution.

关键词： Biological early warning system Electrochemically active bacteria Water toxicity determination Biosensor Heavy metal pollution Early warning

Combustion Synthesis of MgSiN2Powder at Different Nitrogen Pressures

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Journal of Materials Science and Chemical Engineering 2019年第10期7卷 49-57页

作者： Mingu Zhou Senjing Zhang Qingda Li xuemei yi Institute of Water-Saving Agriculture in Arid Areas of China (IWSA) Yangling China College of Mechanical and Electronic Engineering Northwest A&F University Yangling China

MgSiN2 powders have been synthesized by combustion synthesis (CS) using Mg and Si3N4 as starting materials at different nitrogen pressures. The CSed powders were then sintered by spark plasma sintering (SPS) to obtain dense bulk MgSiN2 product. Analysis of the CSed powder using X-ray diffraction (XRD) revealed single-phase MgSiN2 was obtained by CS method. However, the CSed product can be divided into three distinct parts according to its color. Scanning electron microscopy (SEM) observation revealed the grain size and crystallinity decrease gradually from the center to the outer layer. Some small grains clustered together to form larger particles, and there were a large number of pores among the clusters. The grain size seemed increasing with the increase of nitrogen pressure. The bulk density of CS-SPSed MgSiN2 was 3.11 g/cm3, Vickers hardness was 1673.1 kgf/mm2, and thermal diffusivity was 8.718E−2 cm2/s.

关键词： Magnesium Silicon Nitride Combustion Synthesis Microstructure Thermal Diffusivity

Recycling of Secondary Aluminum Dross to Fabricate Porous γ-Al2O3Assisted by Corn Straw as Biotemplate

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Journal of Materials Science and Chemical Engineering 2019年第12期7卷 87-102页

作者： Senjing Zhang Weijun Zhu Qingda Li Wenjie Zhang xuemei yi College of Mechanical and Electronic Engineering Northwest A&F University Yangling China

In the aluminum industry, secondary aluminum dross (SAD) is an inevitable solid residue, which usually contains 30 - 70 wt% Al2O3. In this work, Al(OH)3 was extracted from SAD through acid-leaching and alkali purification process. The as-obtained Al(OH)3 precipitation then was calcinated to synthesize porous γ-Al2O3 assisting by an agricultural waste biomass-corn straw as biotemplate. Effects of H2SO4 concentration, reaction temperature and time on the recovery of SAD were investigated. Furthermore, the dependence of calcination temperature on specific surface area, pore volume and content of porous γ-Al2O3 was analyzed. X-ray diffraction (XRD) and X-ray fluorescence (XRF) were used to inspect the phase compositions and their contents, respectively. Scanning electron microscopy (SEM) was employed to analyze the morphologies of the sintered porous γ-Al2O3. It was found that the highest recycle rate of aluminum from SAD was obtained under optimum conditions of 80°C, acid concentration of 1.6 mol/l, and reaction time of 5 h by acid process. The porous γ-Al2O3 with specific surface area, 261.22 m2/g and average pore diameter, 52.64 nm, was obtained under calcination at 850°C through mixing the as-obtained Al(OH)3 precipitation and corn straw.

关键词： Secondary Aluminum Dross Purification Biotemplate Corn Straw Al2O3

Synthesis of MgSiN2Powders from the Mg-Si System

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Journal of Materials Science and Chemical Engineering 2018年第1期6卷 68-79页

作者： Ran Guo xuemei yi Xiongzhang Liu Qingda Li Takahiro Nomura College of Mechanical and Electronic Engineering Northwest A & F University Shaanxi China Center for Advanced Research of Energy and Materials Hokkaido University Sapporo Japan

Magnesium silicon nitride (MgSiN2) was synthesized without any additives under a nitrogen gas flow (200 mL/min) using a nitriding method. The effects of temperature and holding time on its purity and morphology were investigated. A single-phase MgSiN2 powder was obtained at 1350℃ for 1 h and 1250℃ for 11 h. However, the decomposition of MgSiN2 occurred at 1450℃, suggesting that the optimum temperature for the preparation of MgSiN2 from Mg-Si system was 1350℃. The phase purity, morphology, size of the product and elemental composition of the samples were detected by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy spectrometer (EDS), respectively. The evaporation of Mg and Si resulted in the formation of many voids in the blocky product. The temperature gradient promotes the growth of MgSiN2 on the surface of massive products along the tip. The concentration gradient of Mg and Si vapors in the void resulted in the columnar growth of MgSiN2.

关键词： Nitride Materials Crystal Growth X-Ray Diffraction Mg-Si System

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阅微草堂收藏诸老尺牍

文献 2005年第2期 23-41页

作者：易雪梅曾雪梅甘肃省图书馆历史文献部

二十一通,皆清大学士梁国治、朱珪、刘墉、翁方纲、钱大昕、彭元瑞、王杰、戴震、吴省兰,及清宗室固山贝子弘旰写与纪昀的信函,其后有纪树馨收藏跋."阅微草堂"为纪昀的书斋名.纪昀(1724-1805),字晓岚,一字春帆,号石云,又号观弈道人、孤... 详细信息

二十一通,皆清大学士梁国治、朱珪、刘墉、翁方纲、钱大昕、彭元瑞、王杰、戴震、吴省兰,及清宗室固山贝子弘旰写与纪昀的信函,其后有纪树馨收藏跋."阅微草堂"为纪昀的书斋名.纪昀(1724-1805),字晓岚,一字春帆,号石云,又号观弈道人、孤石老人.世称茶星、纪河间.清雍正二年六月出生于直隶献县(今属河北省沧县).乾隆十九年(1754)中进士,选为翰林院庶吉士.

关键词：四库全书馆甘肃省图书馆金川朱硅阅微草堂乾隆老尺桂未谷拜启翁方纲刘墉清史稿

Impact of Asarum Essential Oils on Physiological and Biochemical Indicators of Two Agricultural Pests

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Plant Diseases and Pests 2014年第3期5卷 1-6页

作者： Liu Yan Ji Lanzhu Wang Guiqing Wang Yuanxia Zhang Yue yi xuemei Institute of Applied Ecology Chinese Academy of Sciences College of Agronomy Liaocheng University Graduate University of Chinese Academy of Sciences

[Objective]The paper was to study the effects of asarum essential oils on physiological and biochemical indices of two agricultural pests. [Method]Asarum essential oils were extracted by different methods,and their effects on physiological and biochemical indices related to the structure of body wall（ chitin and phenoloxidase）,the physiological and biochemical indices acting on the nervous system（ Acetylcholinesterase）,and the physiological and biochemical indices acting on the digestive system（ protease,amylase and lipase） of Ostrinia furnacalis and Mythimna seperata were studied. [Result]Asarum essential oils had no effect no chitin content of body wall under the experimental concentration,and had no inhibitory effect but activated effect on polyphenol oxidase activity. Asarum essential oils could act on the nervous system of insect,and had strong inhibitory effect against acetylcholinesterase activity of O. furnacalis larvae,with inhibition rates of 24. 86%- 38. 79%. Asarum essential oils showed a significant activated effect on pepsin activity in midgut,but the activated amplitude became smaller with the prolongation of treatment time. Asarum essential oils showed a significant inhibitory effect on activities of amylase and lipase,indicating that it could play an insecticidal effect by inhibiting activity of amylase and lipase,and it could act on digestive system of insect. [Conclusion]The study laid the foundation for further development of asarum as botanical pesticide.

关键词： Plant essential oil Asarum Ostrinia furnacalis Mythimna seperata Physiological and biochemical indices

基于振动特性和电学特性的行波超声电机非线性带载骤停现象研究

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中国电机工程学报 2017年第16期37卷 4819-4825页

作者：牛子杰闫锋欣孙志峻衣雪梅西北农林科技大学机械与电子工程学院陕西省西安市712100 机械结构力学及控制国家重点实验室(南京航空航天大学) 江苏省南京市210016

当前航空航天领域内对超声电机,特别是行波型超声电机(下文简称超声电机)的需求越来越大。而超声电机在使用过程中的非线性现象导致的问题越来越突出。目前亟待解决的超声电机非线性问题是超声电机工作在一定的扭矩负载(小于堵转扭矩)... 详细信息

当前航空航天领域内对超声电机,特别是行波型超声电机(下文简称超声电机)的需求越来越大。而超声电机在使用过程中的非线性现象导致的问题越来越突出。目前亟待解决的超声电机非线性问题是超声电机工作在一定的扭矩负载(小于堵转扭矩)状况下会出现突然停机的现象。该文分别从振动特性和电学特性分析了电机的骤停现象,提出行波型超声电机负载扭矩增加会导致电机定子阻尼和刚度同时增加,从而导致振动阻尼比减小。电机定子振动阻尼比减小会导致电机实际的共振频率升高。同时,负载增大会导致电机系统在同一频率下的阻抗模减小,使得电机实际的共振频率进一步升高。电机驱动频率不变,当电机实际的共振频率升高并从低到高穿越电机驱动频率时,超声电机会出现骤停现象。实验证明,负载扭矩增加导致电机系统阻尼比减小和电机系统阻抗模减小是影响到电机带载骤停的根本原因。

关键词：行波型超声电机受迫振动阻抗特性共振频率阻尼比骤停

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《四库全书》的种数问题

文献 2004年第1期 36-42页

作者：易雪梅吴明亮甘肃省图书馆历史文献部

　　是我国古代乃至十八世纪中叶世界上最大的一部丛书.初缮七份,分庋七阁.……

关键词：《四库全书》收书四库全书文溯阁种数