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Preparation and characterization of a new magnetic fluid with good low temperature resistance

Nano Research 2025年第1期18卷 477-486页

作者： Shilin Nie Decai Li ✉1 department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in advanced equipment Tsinghua UniversityBeijing 100084China

Magnetic fluids are a type of novel functionalmaterial that has emerged over the past two decades, whichhave found applications in various aspects of production anddaily life. However, the application of conventional magneticfluids in low-temperature environments is severely limited andoften unsatisfactory. To address this issue, we havedeveloped a new magnetic fluid with excellent low-temperatureresistance. Initially, bare Fe_(3)O_(4) magnetic nanoparticles(FMNPs) were synthesized via co-precipitation without aprotective gas. Subsequently, these particles were modified using polyethylene glycol (PEG)-4000 as a surfactant. Thebare and modified FMNPs (MFMNPs) were characterized using X-ray diffraction (XRD), vibrating sample magnetometer(VSM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetricanalysis-differential thermal gravimetric (TGA-DTG) analysis. The rheological properties, low-temperature resistance of themagnetic fluid were also evaluated. The characterization results indicate that the MFMNPs are spherical andmonodisperse, with a narrow size distribution and a mean particle size of approximately 12 nm. Furthermore, the FTIRspectra and TGA-DTA results suggest that PEG-4000 is linked to the bare Fe_(3)O_(4) particles via hydrogen bonding, indicatingsuccessful modification of the Fe_(3)O_(4) magnetic nanoparticles using PEG. VSM measurements demonstrate that surfacemodification does not alter the crystal morphology or superparamagnetic of Fe_(3)O_(4). However, it does reduce the saturationmagnetization from 68.17 to 54.75 emu/g. Additionally, the prepared magnetic fluid exhibits shear thinning and magneticviscosity effects. It also exhibits excellent low-temperature resistance, maintaining good fluidity without freezing even at -60 ℃. In summary, these results collectively indicate that the new low-temperature resistant magnetic fluid developed in thisstudy is stable and has broad application prospects.

关键词： magnetic fluid low-temperature resistance polyethylene glycol ethylene glycol aqueous solution superparamagnetic

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Effects of conical nozzle configuration on impulse coupling coefficient in repetitively-pulsed laser propulsion

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Optoelectronics Letters 2009年第3期5卷 190-193页

作者：曹正蕊洪延姬文明 department of Postgraduates the Academy of Equipment Command &Technology department of Basic Science the Academy of Equipment Command &Technology

A dimensionless factor was introduced to deduce the analytic expression of impulse coupling coefficient for conical nozzles in the case of spherical symmetry,and a high precision impact pendulum system was used to measure impulse coupling coefficients of 15 conical nozzles with different cone angles and *** expression was corrected according to experimental *** results indicate that:1) impulse coupling coefficient increases firstly and then decreases with augment of dimensionless length when cone angle is fixed;2) impulse coupling coefficient decreases monotonously with augment of cone angle when dimensionless length is fixed;3) it is of great importance for improving impulse coupling coefficient to increase the rate of laser energy deposition.

关键词：冲量耦合系数重复脉冲锥形喷嘴激光推进配置解析表达式无量纲能量沉积

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Clustering-based maintainability demonstration for complex systems with a mixed maintenance time distribution

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Journal of Systems Engineering and Electronics 2019年第6期30卷 1260-1271页

作者： WU Zhenya HAO Jianping department of equipment command and Management Shijiazhuang Campus of Army Engineering University

During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture *** existing maintainability standards and guidance do not explain explicitly how to deal with this *** paper develops a comprehensive maintainability demonstration method for complex systems with a mixed maintenance time *** of all,a K-means algorithm and an expectation-maximization(EM)algorithm are used to partition the maintenance time data for all possible *** Bayesian information criterion(BIC)is then used to choose the optimal *** this,the clustering results for equipment are obtained according to their degree of *** degree of similarity for the maintainability of different kinds of equipment is then determined using the projection *** using a Bootstrap method,the prior distribution is obtained from the maintenance time data for the most similar ***,a test method based on Bayesian theory is outlined for the maintainability ***,the viability of the proposed approach is illustrated by means of an example.

关键词： complex system maintainability demonstration mix ture distribution model Bayesian test.

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Investigation on Mechanism of Altitude Characteristic for Air-breathing Pulsed Laser Thruster

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Chinese Journal of Aeronautics 2010年第1期23卷 33-38页

作者： Hong Yanji,Wen Ming,Cao Zhengrui department of Basic Theories,Academy of equipment command & Technology,Beijing 101416,China department of Basic Theories Academy of Equipment Command & Technology Beijing 101416 China

Altitude characteristic is of great importance for studying when an air-breathing pulsed laser thruster works in the dense atmosphere condition of 0-30 km altitude. The experimental findings all over the world show that the similar relationship between impulse coupling coefficient and altitude. According to strong explosion theory and an ideal gas model,a dimensionless factor indicating energy law of similitude is introduced,and formula of impulse coupling coefficient is deducted. Then theoretical study of altitude characteristic is carried out and mechanism of altitude characteristic is further explained. The results indicate that there is a maximum value of impulse coupling coefficient if the dimensionless factor equals to 0.41 in theory, and whether the phenomena of maximum appear or not depends on the range of the dimensionless factor related to altitude. As to a conical nozzle with the fixed length of 120 mm, the relationship between the sonic velocity and the dimensionless factor causes the maximum phenomenon at the altitude of about 12.5 km,and maximum theoretical impulse coupling coefficient is also found in the experimental investigations. The mechanism of altitude characteristic for air-breathing pulsed laser thruster is discovered in this article, which will provide reference for further research on altitude characteristic.

关键词： laser propulsion air-breathing mode altitude characteristic dimensionless factor maximum phenomenon

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Research on Network Maintenance Strategy Selection Based on Analytic Hierarchy Process and Technique for Order Preference by Similarity to Ideal Solution Algorithm

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Journal of Shanghai Jiaotong university(Science) 2016年第5期21卷 588-593页

作者：夏伟石全王芳戈洪宇陈材 department of equipment command & Management Mechanical Engineering College

Network maintenance strategy selection is a multi-objective decision making topic. It mostly depends on the uncertainty and fuzziness of decision makers and conditions. In this paper, based on analytic hierarchy process(AHP) and technique for order preference by similarity to ideal solution(TOPSIS), TOPSIS partial order method is proposed to choose the optimal maintenance strategy. This method uses AHP to determine the weights of evaluation indexes. The optimal maintenance strategy choice is given as an example to demonstrate the effectiveness of the method.

关键词： analytic hierarchy process(AHP) technique for order preference by similarity to ideal solution(TOPSIS) maintenance strategies selection

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Study of spiral cruising surveillance orbit for GEO debris

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Journal of Beijing Institute of Technology 2016年第S2期25卷 68-72页

作者：周海俊张雅声徐艳丽李智 Company of Postgraduate Management Equipment Academy department of Space equipment Equipment Academy department of Space command Equipment Academy

A new type of relative orbit configuration for space target surveillance is proposed,performing autonomous rendezvous,proximity and surveillance operations with multiple non-cooperative targets at geosynchronous orbit in spiral precession *** deviation orbit element is used to describe the relative motion characteristics of the spiral cruising surveillance orbit,and the necessary condition to perform spiral precession is *** features of the spiral ring in the in-plane of the target orbit are detailedly *** position of the crossing point,the relationship between the fly-around period of the spiral ring and the relative configuration parameters is *** avoid the collision with the debris,two schemes of the relative orbit configuration are *** is carried out to verify the performance of the spiral cruising surveillance orbit by satellite tool kits(STK).

关键词： space target surveillance orbit design small deviation orbit element spiral cruising orbit spiral ring

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Study on Simulation Modeling and Evaluation of equipment Maintenance

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Journal of Shanghai Jiaotong university(Science) 2016年第5期21卷 594-599页

作者：庞升贾云献刘鑫邓雅冲 department of equipment command and Management Mechanical Engineering College

Aiming at the actual demand for the maintenance support of new general equipments, this paper analyzes the structure and circulation of maintenance support system, builds the simulation model of running process by entity flow chart method, and constructs the basic frame of the simulation model. The generating method of random variables and the advancing process of the simulation clock are described, and the accurate prediction of maintenance equipment is realized. Moreover, the material readiness rate is analyzed in statistics objective to evaluate the simulation result. The research is of significance for improving the efficiency of equipment maintenance and the promotion of material readiness rate.

关键词： equipment maintenance simulation modeling material readiness rate

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Electromagnetic Inverse Scattering of Multiple Perfectly Conducting Cylinders by CSA-GA （TE Case） 3

Electromagnetic Inverse Scattering of Multiple Perfectly Con...

引用

2002 3rd International Conference on Microwave and Millimeter Wave Technology

作者： Wang Jiancheng department of equipment and command ICTE

ISBN: (纸本)078037486X

＜正＞Genetic algorithm with Chromosome structure adjustment（CSA-GA） technique is used for the first time in this paper to study the electromagnetic inverse scattering of multiple perfectly conducting cylinders for TE *** CSA-GA exhibits lots of merits such as strong search ability,simplicity,robustness,and faster convergence than those of usually adopted GA despite of still being very time consuming.

关键词： electromagnetic wave scattering conducting bodies genetic algorithms inverse problems electromagnetic inverse scattering multiple perfectly conducting cylinders CSA-GA technique TE mode genetic algorithm chromosome structure adjustment

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Effect of Nose Shape on Semi-Armor-Piercing Warhead Penetration Performance

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Journal of Shanghai Jiaotong university(Science) 2015年第4期20卷 468-471页

作者：石全熊飞刘锋陈材 department of equipment command & Management Mechanical Engineering College

The numerical simulations of different head shape semi-armor-piercing warheads penetrating thin steel target are done using the finite element software ANSYS/LS-DYNA, and the whole process of different nose shape semi-armor-piercing warheads vertically penetrating the thin steel plate is compared. Besides, the influence of impact angle on penetration performance of three different nose shape projectiles is researched. The analysis results indicate that the nose shape has a significant influence on semi-armor-piercing warhead penetration *** effect of impact angle on the three kinds of projectiles' residual kinetic energy and deflection is different. The research results provide references for designing of warhead and battlefield damage assessment.

关键词： penetration head shape finite element

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equipment Maintenance Mode Based on Network Environment

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Journal of Donghua University(English Edition) 2015年第1期32卷 171-174页

作者：庞升贾云献李欣玥邓雅冲 department of equipment command and Management Mechanical Engineering College

Aimed at the actuality of Peoplep's Liberation Army(PLA) army equipment maintenance, this paper develops equipment maintenance mode based on network,and focuses on the design of maintenance decision-making system. Analyzing maintenance weight is applied to making decision of repair *** purpose of the research is introducing basic concept and setting up an equipment maintenance mode using military *** mode based on network can reduce the costs,enhance the maintenance efficiency, and save the human resource and finance.

关键词： equipment maintenance failure diagnose maintenance decision-making network

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