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轮轨两点接触的有限元分析

机械工程学报 2005年第11期41卷 121-126页

作者：刘迎曦张军大连理工大学工业装备结构分析国家重点实验室大连116024 同济大学航空航天与力学学院上海200092

在轮轨单点接触计算分析的基础上,建立锥形踏面车轮的轮缘贴靠钢轨形成两点接触的计算模型,应用有限元参数二次规划法分析这一弹塑性接触问题。对不同载荷作用下的轮轨两点接触模型分别进行计算,得出了大量的轮轨接触状态、接触力的分... 详细信息

在轮轨单点接触计算分析的基础上,建立锥形踏面车轮的轮缘贴靠钢轨形成两点接触的计算模型,应用有限元参数二次规划法分析这一弹塑性接触问题。对不同载荷作用下的轮轨两点接触模型分别进行计算,得出了大量的轮轨接触状态、接触力的分布及变化规律。这些计算结果将有助于找到缓解钢轨侧磨和轮缘磨耗的方法。

关键词：两点接触有限元法参数二次规划法轮轨接触力

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战后日本集合住宅的发展

新建筑 2001年第2期 47-49页

作者：张菁刘颖曦天津大学建筑学院天津300072

概括介绍了日本在二次世界大战后５０年里，各个时期的集合住宅发展情况。２０世纪８０年代起日本年轻一代建筑师对集合住宅类型大胆的尝试，使日本集合住宅出现了多元化的趋势。

关键词：日本集合住宅多元化住宅功能

Numerical simulation of soft palate movement and airflow in human upper airway by fluid-structure interaction method

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Acta Mechanica Sinica 2007年第4期23卷 359-367页

作者： Xiuzhen Sun Chi Yu Yuefang Wang yingxi liu State Key Lab.of Struct.Anal.for Ind.Equip.,Dalian University of Technology,Dalian 116024,China The Second Affiliated Hospital,Dalian Medical University,Dalian 116027,China State Key Lab. of Struct. Anal. for Ind. Equip. Dalian University of Technology Dalian China The Second Affiliated Hospital Dalian Medical University Dalian China

In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images of a healthy person and a patient with Obstructive Sleep Apnea-Hypopnea Syndrome （OSAHS）, three-dimensional models of upper airway cavity and soft palate are reconstructed by the method of surface rendering. Numerical simulation is performed for airflow in the upper airway and displacement of soft palate by fluid-structure interaction analysis. The reconstructed threedimensional models precisely preserve the original configuration of upper airways and soft palate. The results of the pressure and velocity distributions in the airflow field are quantitatively determined, and the displacement of soft palate is presented. Pressure gradients of airway are lower for the healthy person and the airflow distribution is quite uniform in the case of free breathing. However, the OSAHS patient remarkably escalates both the pressure and velocity in the upper airway, and causes higher displacement of the soft palate. The present study is useful in revealing pathogenesis and quantitative mutual relationship between configuration and function of the upper airway as well as in diagnosingdiseases related to anatomical structure and function of the upper airway.

关键词： Obstructive sleep apnea-hypopnea syndrome Upper airway Soft palate Three-dimensional finiteelement reconstruction Fluid-structure interaction Numerical simulation

Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu liu Chongru liu North China Electric Power University Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC ***,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC ***,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is ***,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind *** simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed

A Novel Design of a Pre-separation Panel Structure to Protect Against the Impact of an Explosion in an Aircraft Plenum Chamber

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Acta Mechanica Solida Sinica 2024年第1期37卷 166-180页

作者： Zongxing liu Xiang Yang Jun liu School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China COMAC Shanghai Aircraft Design and Research Institute Shanghai 201210China

To reduce the damage of the pressurizing panel structure of a fuselage caused by an explosion at the“least risk bomb location”in an aircraft structure,a new pre-separation panel structure was designed to resist blast ***,the dynamic strain response and morphology of impact damage of the new pre-separation panel were measured in an impact damage ***,the commercial software LS-DYNA was used to calculate the propagation of the blast shock wave,and the results were compared with empirical equations to verify the rationality of the numerical calculation ***,the fluid–structure coupling method was used to calculate the damage process of the pre-separation panel structure under the impact of an explosion wave and an impact *** calculated results were in good agreement with the test results,which showed the rationality of the calculation method and the *** residual strength of the damaged pre-separation panel was significantly higher than that of the original damaged *** results show that the new pre-separation panel structure is reasonable and has certain significance for guiding the design of plenum chambers with strong resistance to implosion for aircraft fuselages.

关键词： Pre-separation panel structure Explosive response Residual strength Aircraft plenum chamber Least risk bomb location

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基于植酸框架构筑燃料电池用阴离子导电膜

石油化工高等学校学报 2023年第1期36卷 74-80页

作者：刘盈汐王吉林王璐璐曲志强辽宁石油化工大学石油化工学院辽宁抚顺113001 铁岭选矿药剂有限公司辽宁铁岭112002

在聚乙烯醇聚合物基质中原位引入植酸、甲醇、水、九水合硝酸铬和N,N-二甲基甲酰胺的混合液(植酸与九水合硝酸铬形成具有立体结构的金属有机框架结构),以戊二醛为交联剂,将聚乙烯醇聚合物交联为网状结构,由此构筑一系列内部含有基于植... 详细信息

在聚乙烯醇聚合物基质中原位引入植酸、甲醇、水、九水合硝酸铬和N,N-二甲基甲酰胺的混合液(植酸与九水合硝酸铬形成具有立体结构的金属有机框架结构),以戊二醛为交联剂,将聚乙烯醇聚合物交联为网状结构,由此构筑一系列内部含有基于植酸构筑的多孔金属有机框架结构(MOF)及适合燃料电池使用的阴离子导电膜(MOF@PVA);通过调节阴离子导电膜中Cr^(3+)的质量分数,对其结构及性能进行优化。结果表明,制得的导电膜形貌平整均一,内部含有大量可供OH−迁移和涵养水分子的孔结构;导电膜的电导率、含水率、机械性能均随着Cr^(3+)质量分数的增加而增加。其中,当m(Cr^(3+))/m(导电膜)=0.012时,导电膜的电导率最高,为24.9 mS/cm;导电膜在80℃、3 mol/L NaOH溶液中浸泡168 h后,电导率仅下降8%。

关键词：阴离子导电膜电导率耐碱性植酸 MOF

Effectiveness and safety of acupuncture in treatment of pregnancyrelated symptoms:a systematic review and Meta-analysis

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Journal of Traditional Chinese Medicine 2024年第1期44卷 16-26页

作者： liu Tingting liu Tongou liu Mingfu School of Traditional Chinese Medicine Clinical Medicine Hubei University of Traditional Chinese MedicineWuhan 430000China First Clinical College of Hubei University of Traditional Chinese Medicine Wuhan 430000China Department of Acupuncture and Tuina Affiliated Hospital of Hubei University of Traditional Chinese MedicineHubei Provincial Hospital of Traditional Chinese MedicineWuhan 430000China

OBJECTIVE:To systematically evaluate the efficacy and safety of acupuncture(AM)in the treatment of pregnancyrelated symptoms such as acute vomiting during ***:We comprehensively searched the available literature up to November 2021,including Pub Med,Embase,Cochrane Library,Chinese Biomedical Literature Database,and China National Knowledge Infrastructure Database,for randomized controlled trials(RCTs)on AM for the treatment of severe vomiting,insomnia,pharyngeal and pelvic pain,mood abnormalities,and dyspepsia during ***:Sixteen RCTs with a cumulative sample size of 1178 cases were *** these,964 patients were included in the *** Meta-analysis results showed that AM was more efficient than Western medicine in treating discomfort during pregnancy[odds ratio(OR)=1.19,95%confidence interval(CI)(1.11,1.28),P<0.01].AM was better than the control group in improving the visual analog scale scores[standard mean difference(SMD)=0.62,95%CI(0.53,0.71),P<0.01].AM was superior to the control group in improving Numerical Rating Scale(NRS)symptom scores[OR=7.31,95%CI(3.36,15.94),P<0.01].There was no significant difference in adverse effects between the AM and sham-AM groups and the analgesic drug group[OR=0.70,95%CI(0.39,1.28),P=0.25],but the treatment and control groups had mild adverse effects with a low ***:AM is more effective than other treatments or pharmacotherapy alone in the treatment of pregnancy-related symptoms,and is relatively ***,the quality of the included trials was rather poor,and high-quality studies are required to confirm our findings.

关键词： acupuncture pregnancy nausea vomiting sleep initiation and maintenance disorders low back pain pelvic pain mood abnormalities Meta-analysis systematic review

Stochastic Unit Commitment with High-Penetration Offshore Wind Power Generation in Typhoon Scenarios

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 535-546页

作者： Yanqi liu Dundun liu Hongcai Zhang State Key Laboratory of Internet of Things for Smart City and Department of Electrical and Computer Engineering University of MacaoMacao 999078China University of Macao Zhuhai UM Science and Technology Research Institute ZhuhaiChina

To tackle the energy crisis and climate change,wind farms are being heavily invested in across the *** China's coastal areas,there are abundant wind resources and numerous offshore wind farms are being *** secure operation of these wind farms may suffer from typhoons,and researchers have studied power system operation and resilience enhancement in typhoon ***,the intricate movement of a typhoon makes it challenging to evaluate its spatial-temporal *** published papers only consider predefined typhoon trajectories neglecting *** address this challenge,this study proposes a stochastic unit commitment model that incorporates high-penetration offshore wind power generation in typhoon *** adopts a data-driven method to describe the uncertainties of typhoon trajectories and considers the realistic anti-typhoon mode in offshore wind farms.A two-stage stochastic unit commitment model is designed to enhance power system resilience in typhoon *** formulate the model into a mixed-integer linear programming problem and then solve it based on the computationally-efficient progressive hedging algorithm(PHA).Finally,numerical experiments validate the effectiveness of the proposed method.

关键词： Unit commitment two-stage stochastic programming offshore wind farm typhoon

Devolatilization of high viscous fluids with high gravity technology

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Chinese Journal of Chemical Engineering 2024年第7期71卷 249-257页

作者： Jibing Qi Youzhi liu Yandong liu Taiyuan University Taiyuan 030032China Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering North University of ChinaTaiyuan 030051China

Volatile organic compounds(VOCs)are generally toxic and harmful substances that can cause health and environmental *** removal of VOCs from polymers has become a key *** effective devolatilization to remove VOCs from high viscous fluids such as polymer is necessary and is of great *** this study,the devolatilization effect of a rotating packed bed(RPB)was studied by using polydimethylsiloxane as the viscous fluid and acetone as the *** devolatilization rate and liquid phase volume(KLa)have been *** results indicated that the optimum conditions were the high-gravity factor of 60,liquid flow rate of 10 L·h^(-1),and vacuum degree of 0.077 *** dimensionless correlation of KLa was established,and the deviations between predicted and experimental values were less than±28%.The high-gravity technology will result in lower mass transfer resistance in the devolatilization process,enhance the mass transfer process of acetone,and improve the removal effect of *** work provides a promising path for the removal of volatiles from polymers in combination with high-gravity *** can provide the basis for the application of RPB in viscous fluids.

关键词： High-gravity technology Devolatilization rate High viscous fluid Volatile organic compounds(VOCs)