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Neural-network-based terminal sliding-mode control for thrust regulation of a tethered space-tug

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Astrodynamics 2018年第2期2卷 175-185页

作者： Rui Zhong shijie xu School of Astronautics Beihang UniversityBeijingChina

This paper studies the thrust regulation of the tethered space-tug in order to stabilize the target towed by a flexible *** compromise between model accuracy and simplicity,a rigid-flexible coupling multi-body model is proposed as the full model of the tethered *** specifically,the tug and the towed target are assumed as rigid bodies,whereas the flexible tether is approximated as a series of hinged *** rods are assumed extensible but *** the equations of motion of the multi-body system are derived based on the recursive dynamics *** attitude motion of the towed target is stabilized by regulating the thrust on the tug,whereas the tether-tension-caused perturbation to the tug's attitude motion is eliminated by the control torque on the *** regulated thrust is achieved by first designing an optimal control trajectory considering the simplified system model with constraints for both state variables and control *** the trajectory is tracked using a neural-network based terminal sliding-mode *** radial basis function neural network is used to estimate the unknown nonlinear difference between the simple model and the full model,while the terminal sliding mode controller ensures the rapid tracking control of the target's attitude *** saturation and tether slackness avoidance are also ***,numerical simulations prove the effectiveness of the proposed controller using the regulated *** disturbing orbital motion much,the attitude motion of the tug and the target are well stabilized and the tether slackness is avoided.

关键词： tethered space-tug thrust regulation flexible tether recursive dynamics algorithm neural network

基于分子动力学的废植物油再生沥青扩散行为研究

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应用化工 2024年第8期53卷 1777-1784页

作者：索智隋昀言赵子豪徐士杰张月王欣欣北京建筑大学土木与交通工程学院北京100044 北京未来城市设计高精尖创新中心北京100044 北京城市交通基础设施建设工程技术研究中心北京100044

为研究不同废植物油掺配量、扩散温度及时间对废植物油与老化沥青相互扩散行为的影响,提出了考虑沥青老化程度随沥青膜深度变化的三层分子扩散模型,并结合傅里叶红外光谱(FTIR)测试及宏观尺度的软化点试验,分析废植物油再生剂与老化沥... 详细信息

为研究不同废植物油掺配量、扩散温度及时间对废植物油与老化沥青相互扩散行为的影响,提出了考虑沥青老化程度随沥青膜深度变化的三层分子扩散模型,并结合傅里叶红外光谱(FTIR)测试及宏观尺度的软化点试验,分析废植物油再生剂与老化沥青之间的相互扩散行为。结果表明:废植物油再生剂通过补充老化沥青中的轻质组分、减少沥青质的团聚从而实现老化沥青的再生。温度的升高、废植物油掺量及扩散时间的增加均会增强废植物油与老化沥青的相互扩散效率,其中温度的影响最为显著;但随着温度增高,其对于扩散效率的增幅程度降低。皮尔逊相关性分析结果显示,模拟与宏观之间扩散系数相关性显著,三层分子扩散模型能够有效表征再生剂与老化沥青的相互扩散行为。

关键词：道路工程分子模拟扩散性能废植物油老化沥青再生机理

Observation of two-times self-focusing of femtosecond laser beam in ZnO crystal by two-photon luminescence

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Science Bulletin 2018年第21期63卷 1392-1396页

作者： Xiaorui Wang Honggang Ye Zhicheng Su Dapeng Yu shijie xu Department of Physics and Shenzhen Institute of Research and Innovation (HKU-SIRI)The University of Hong KongHong KongChina Department of Physics Southern University of Science and TechnologyShenzhen 518055China Department of Applied Physics Xi'an Jiaotong UniversityXi'an 710049China

By ‘‘seeing" the green two-photon luminescence, two separate focusing points are observed on the propagation axis of a converging femtosecond laser beam in a ZnO single crystal rod. It is found that the selffocusing effect makes a significant contribution to the formation of the first focusing point, while the second focusing point is caused by self-refocusing. The position of the first focusing point is in good agreement with the value predicted by a model developed by Chin and his co-workers. These experimental findings could be the unprecedented evidence for the self-focusing and refocusing effect of the femtosecond laser filament propagation in nonlinear media.

关键词： Self-focusing Self-refocusing ZnO rod Two-photon luminescence

Difference analysis of Doppler ultrasound blood flow of Cunkou(radial artery)pulse,Renying(carotid artery)pulse,and Fuyang(anterior tibial artery)pulse

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Journal of Traditional Chinese Medicine 2023年第1期43卷 168-174页

作者： WANG Chao WU Qiong WANG Zhigang WEI Yun xu shijie Postdoctoral Mobile Station of Chinese Academy of Traditional Chinese medicine Beijing 100700China Zang-xiang Teaching and Research Department the Institute of Basic Theory for Chinese MedicineChina Academy of Chinese Medical SciencesBeijing 100700China Finance Office Shandong College of Traditional Chinese MedicineYantai 264199China Department of Doppler Ultrasound Beijing Anzhen HospitalCapital Medical UniversityBeijing 100029China

OBJECTIVE:To analyze the Doppler ultrasound blood flow of Renying(carotid artery)pulse,Cunkou(radial artery)pulse,and Fuyang(anterior tibial artery)pulse in the normal group and the functional constipation with gastrointestinal heat(FCGH)group,and to compare and explore the differences of Renying,Cunkou and Fuyang ***:Sixty normal subjects and 60 patients with gastrointestinal heat constipation were collected in the department of ultrasound,Beijing Anzhen Hospital,Capital Medical *** ultrasound was used to observe the blood flow indexes including maximum systolic velocity(Vp),maximum diastolic velocity(Vd),mean velocity(Vm),pulse index(PI),resistance index(RI),vascular diameter(D),and circulation blood flow cycle(ET)of Renying pulse,Cunkou pulse and Fuyang pulse in the normal group and patients with gastrointestinal heat *** differences of these three pulses were compared between the normal group and the FCGH ***:The PI,Vp,Vm,RI,and D of the three pulses in the normal group were statistically significant different(P<0.01).In the comparison of Doppler flow diagram of three pulses in the FCGH group,there were significant differences in PI,Vd,Vp,Vm,RI,and D(P<0.01).CONCLUSION:Under normal conditions,the indexes of Renying pulse Doppler flow diagram,Cunkou pulse Doppler flow diagram,and Fuyang pulse Doppler flow diagram are significantly *** the FCGH group,most of the indexes of Renying pulse Doppler flow diagram,Cunkou pulse Doppler flow diagram,and Fuyang pulse Doppler flow diagram are *** result verified the necessity of simultaneous examinations of all Renying,Cunkou,and Fuyang pulses in modern Chinese medicine.

关键词： Cunkou pulse Renying pulse Fuyang pulse Doppler flow diagram functional constipation gastrointestinal heat type pulse index resistance index

Adaptive control for autonomous rendezvous of spacecraft on elliptical orbit

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Acta Mechanica Sinica 2009年第4期25卷 539-545页

作者： Shan Lu shijie xu School of Astronautics, Beihang University,100191 Beijing, China School of Astronautics Beihang University Beijing China

A strategy for spacecraft autonomous rendezvous on an elliptical orbit in situation of no orbit information is developed. Lawden equation is used to describe relative motion of two spacecraft. Then an adaptive gain factor is introduced, and an adaptive control law for auton- omous rendezvous on the elliptical orbit is designed using Lyapunov approach. The relative motion is proved to be ultimately bounded under this control law, and the final relative position error can achieve the expected magnitude. Simulation results indicate that the adaptive control law can realize autonomous rendezvous on the elliptical orbit with relative state information only.

关键词： Autonomous rendezvous Elliptical orbit Lyapunov approach Adaptive control Gain factor

响应面法优化深共晶溶剂催化制备己二酸二异辛酯

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工程塑料应用 2024年第4期52卷 148-153页

作者：徐世洁胡志泉沈国良郑荣荣温瑞阳刘岳雷沈阳工业大学石油化工学院辽宁辽阳111003

深共晶溶剂作为新一代绿色溶剂,因合成纯化工艺简单、原料成本低、可再生、生物相容性好等特点而受到科技界的广泛关注。以对甲苯磺酸-甜菜碱制备的深共晶溶剂作为反应溶剂兼催化剂,催化合成增塑剂己二酸二异辛酯(DOA),解决传统催化剂... 详细信息

深共晶溶剂作为新一代绿色溶剂,因合成纯化工艺简单、原料成本低、可再生、生物相容性好等特点而受到科技界的广泛关注。以对甲苯磺酸-甜菜碱制备的深共晶溶剂作为反应溶剂兼催化剂,催化合成增塑剂己二酸二异辛酯(DOA),解决传统催化剂的循环使用问题。采用响应面法,选取醇酸物质的量比、催化剂物质的量比和反应温度三个因素,以酯化率为响应值,利用Box-Behnken设计分析了各因素及其交互作用对酯化率的影响,得到了多项式回归方程模型。结果表明,最佳试验条件为醇酸物质的量比为3.217、催化剂物质的量比为2.310和反应温度为117.7℃。在该条件下,合成DOA的酯化率可以达到88.21%,与模型预测值(92.112%)接近。表明响应面法优化了深共晶溶剂催化合成DOA的工艺参数,具有较高的准确性和有效性。此外,该深共晶溶剂在循环测试8次后,酯化率仍保持在80%左右。经傅里叶变换红外光谱仪和核磁共振氢谱仪进行结构表征分析确定产物为DOA。

关键词：深共晶溶剂催化剂酯类增塑剂酯化绿色合成响应面法

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基于“阴阳水火气血论”辨治围绝经期综合征

江苏中医药 2024年第3期56卷 6-9页

作者：彭彬张逸雯王猛徐世杰中国中医科学院中医基础理论研究所北京100700

围绝经期综合征是机体内分泌、心理、代谢平衡紊乱从而引发多个器官系统症状与体征的综合症候群。基于“阴阳水火气血论”,精血亏虚被认为是产生围绝经期综合征的始动因素,气火俱病是围绝经期综合征诸多症状产生的关键环节,痰瘀交结是... 详细信息

围绝经期综合征是机体内分泌、心理、代谢平衡紊乱从而引发多个器官系统症状与体征的综合症候群。基于“阴阳水火气血论”,精血亏虚被认为是产生围绝经期综合征的始动因素,气火俱病是围绝经期综合征诸多症状产生的关键环节,痰瘀交结是围绝经期综合征诸症缠绵难愈的核心要素。临证倡导从机体阴阳、气血、水火以及痰饮瘀血角度出发,养血益精以治其本,理气降火以治其标,化痰活血以调其枢。通过总结复杂症候群中蕴含的普遍规律,执简驭繁,便于把握围绝经期综合征发生发展之机理,以期为临床提供新的思路。附验案1则以佐证。

关键词：围绝经期综合征阴阳水火气血痰瘀养血益精理气降火化痰活血

Progress of Pharmaceutical Continuous Crystallization

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Engineering 2017年第3期3卷 354-364页

作者： Dejiang Zhang shijie xu Shichao Du Jingkang Wang Junbo Gong School of Chemical Engineering and Technology State Key Laboratory of Chemical Engineering Tianjin University Tianjin 300072. China Collaborative Innovation Center of Chemical Science and Chemical Engineering Tianjin University Tianjin 300072 China

Crystallization is an important unit operation in the pharmaceutical industry. At present, most pharmaceutical crystallization processes are performed in batches. However, due to product variability from batch to batch and to the low productivity of batch crystallization, continuous crystallization is gaining increasing attention. In the past few years, progress has been made to allow the products of continuous crystallization to meet different requirements. This review summarizes the progress in pharmaceutical continuous crystallization from a product engineering perspective. The advantages and disadvantages of different types of continuous crystallization are compared, with the main difference between the two main types of crystallizers being their difference in residence time distribution. Approaches that use continuous crystallization to meet different quality requirements are summarized. Continuous crystallization has advantages in terms of size and morphology control. However, it also has the problem of a process yield that may be lower than that of a batch process, especially in the production of chirality crystals. Finally, different control strategies are compared.

关键词： Continuous crystallization Pharmaceutical MSMPR Tubular crystallizer Control strategy

Determination of metastable zone and induction time of analgin for cooling crystallization

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Chinese Journal of Chemical Engineering 2017年第3期25卷 313-318页

作者： Ling Zhou Zhao Wang Meijing Zhang Mingxia Guo shijie xu Qiuxiang Yin School of Chemical Engineering and Technology State Key Laboratory of Chemical EngineeringTianjin UniversityTianjin 300072China Collaborative Innovation Center of Chemical Science and Chemical Engineering Tianjin 300072China

The solubility, metastable zone width, and induction time of analgin for unseeded batch cooling crystallization in ethanol–aqueous system were experimentally determined. The solubility data could be well described by the van't Hoff equation model. The metastable zone width at various cooling rates was measured, and some parameters of nucleation kinetic were calculated using the Ny'vlt theory. Furthermore, the induction period of various temperatures and supersaturation ratios was also measured. According to classical nucleation theory, some nucleation parameters and interfacial energy was calculated through the induction time(t_(ind)) data. Homogeneous nucleation tended to occur when the supersaturation is high, whereas heterogeneous nucleation was more likely to occur when the supersaturation is low.

关键词： Analgin Cooling crystallization Primary nucleation Metastable zone Induction time