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Earthquake Engineering and Engineering Vibration 2019年第2期18卷 351-362页

作者： Amit Thakur Deepankar Kumar Ashish Surender Kumar Verma Civil Engineering Department Kurukshetra University Civil Engineering Department Maharaja Agrasen Institute of Technology Maharaja Agrasen University Civil Engineering Department Punjab Engineering College (Deemed to be University)

In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y).

关键词： rooftop telecommunication tower set back-step back building response spectrum analysis steel, RC frame, earthquake SAP2000

Wind-induced response analysis of a wind turbine tower including the blade-tower coupling effect

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第11期10卷 1573-1580页

作者： Xiao-bo CHEN1, Jing LI1, Jian-yun CHEN1,2 (1School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China) (2State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China) School of Civil and Hydraulic Engineering Dalian University of Technology Dalian China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian China

To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects, and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method (FEM) was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases (one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower), and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.

关键词： Fluctuating wind velocity Mean wind velocity tower Blade Coupling Wind shear effect Vibration

Experimental Study on Performance of a Closed Wet Cooling tower for Air Wet-Bulb Temperature near 0°C

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Journal of Thermal Science 2019年第5期28卷 1015-1023页

作者： ZHOU Yasu ZHANG Pan ZHAO Jingde YANG Honghai BAI Yufeng College of Environmental Science and Engineering Donghua University

Closed wet cooling towers(CWCTs) are used widely because of their better water quality and smaller water consumption. However, the operating parameters shown in the technical documents are only for rated conditions in summer, not for any other conditions, especially in low air wet-bulb temperature areas such as those near 0℃. In addition, CWCTs often fail to achieve the designed cooling effect at low air wet-bulb temperatures. A experiment set of CWCT was built, and the performance of the CWCT at low air wet-bulb temperature near 0℃ was investigated. The impact of the operating parameters(air flow rate, cooling water flow rate, and spray water flow rate) on the heat and mass transfer performance of the CWCT was measured and analyzed. The results show the cooling performance of the CWCT at an air wet-bulb temperature 0℃, 2℃, and 4℃ is about 47%–63% of the rated operating condition;the optimal operating parameters of these conditions for the CWCT are just the same as those of the rated operating condition in summer. According to the experimental results, some operating advices are given.

关键词： closed wet cooling tower performance of cooling tower low air wet-bulb temperature rated operating parameters evaluation index

Three-dimensional Numerical Study on Thermal Performance of a Super Large Natural Draft Cooling tower of 220m Height

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Journal of Thermal Science 2013年第3期22卷 234-241页

作者： JIN Tai ZHANG Li LUO Kun FAN Jianren State Key Laboratory of Clean Energy Utilization (Zhejiang University) Hunan Electric Power Design Institute

Based on the heat and mass transfer theory and the characteristics of general-purpose software FLUENT, a three-dimensional numerical simulation platform, composed of lots of user defined functions(UDF), has been developed to simulate the thermal performance of natural draft wet cooling towers(NDWCTs). After validation, this platform is used to analyse thermal performances of a 220m high super large cooling tower designed for inland nuclear plant under different operational conditions. Variations of outlet temperature of the cooling tower caused by changes of water flow rates, inlet water temperatures are investigated. Effects of optimization through non-uniform water distributions on outlet water temperature are discussed, and the influences on the flow field inside the cooling tower are analyzed in detail. It is found that the outlet water temperature will increase as the water flow rate increases, but the air flow rate will decrease. The outlet water temperature will decrease 0.095K and 0.205K, respectively, if two non-uniform water distribution approaches are applied.

关键词： Super Large Natural Draft Wet Cooling tower Three-dimensional Numerical Simulation Thermal Performance Non-uniform Water Distribution

Smart Semi-active PID-ACO control strategy for tower vibration reduction in Wind Turbines with MR damper

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Earthquake Engineering and Engineering Vibration 2019年第4期18卷 887-902页

作者： Mahmudur Rahman Zhi Chao Ong Wen Tong Chong Sabariah Julai Department of Mechanical Engineering Faculty of Engineering University of Malaya

Wind turbine technology is well known around the globe as an eco-friendly and eff ective renewable power source. However, this technology often faces reliability problems due to structural vibration. This study proposes a smart semi-active vibration control system using Magnetorheological (MR) dampers where feedback controllers are optimized with nature-inspired algorithms. Proportional integral derivative (PID) and Proportional integral (PI) controllers are designed to achieve the optimal desired force and current input for MR the damper. PID control parameters are optimized using an Ant colony optimization (ACO) algorithm. The eff ectiveness of the ACO algorithm is validated by comparing its performance with Ziegler-Nichols (Z-N) and particle swarm optimization (PSO). The placement of the MR damper on the tower is also investigated to ensure structural balance and optimal desired force from the MR damper. The simulation results show that the proposed semi-active PID-ACO control strategy can signifi cantly reduce vibration on the wind turbine tower under diff erent frequencies (i.e., 67%, 73%, 79% and 34.4% at 2 Hz, 3 Hz, 4.6 Hz and 6 Hz, respectively) and amplitudes (i.e. 50%, 58% and 67% for 50 N, 80 N, and 100 N, respectively). In this study, the simulation model is validated with an experimental study in terms of natural frequency, mode shape and uncontrolled response at the 1st mode. The proposed PID-ACO control strategy and optimal MR damper position is also implemented on a lab-scaled wind turbine tower model. The results show that the vibration reduction rate is 66% and 73% in the experimental and simulation study, respectively, at the 1st mode.

关键词： ant colony optimization fi nite diff erence method magnetorheological damper PID-ACO controller semiactive control system identifi cation wind turbine tower

Some key technics of drop tower experiment device of National Microgravity Laboratory (China) (NMLC)

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Science China(Technological Sciences) 2005年第3期48卷 305-316页

作者： ZHANG Xiaoqian 1 , YUAN Longgen 1 , WU Wendong 1 , TIAN Lanqiao 2 & YAO Kangzhuang 2 1. Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100080, China 2. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China Institute of Engineering Thermophysics Chinese Academy of Sciences

Drop tower is an important ground based facility for microgravity science experiment. The technical performances of the drop tower NMLC are advanced compared with similar facilities in the US, Germany and Japan. The main components such as drop capsule, deceleration devices, release mechanism present its advantages and creativities.

关键词： drop tower facility,drop capsule,deceleration devices,release mechanism.

Efficacy and Safety of Teriflunomide in Chinese Patients with Relapsing Forms of Multiple Sclerosis: A Subgroup Analysis of the Phase 3 tower Study

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Chinese Medical Journal 2018年第23期131卷 2776-2784页

作者： Wei Qiu De-Hui Huang Shi-Fang Hou Mei-Ni Zhang Tao Jin Hui-Qing Dong Hua Peng Chao-Dong Zhang Gang Zhao Yi-Ning Huang Dong Zhou Wei-Ping Wu Bao-Jun Wang Ji-Mei Li Xing-Hu Zhang Yan Cheng Hai-Feng Li Ling Li Chuan-Zhen Lu Xu Zhang Bi-Tao Bu Wan-Li Dong Dong-Sheng Fan Xue-Qiang Hu Xian-Hao Xu Department of Neurology The Third Affiliated Hospital of Sun Yat-Sen UniversityGuangzhouGuangdong 510000China Department of Neurology Peking University First HospitalBeijing 100034China Department of Neurology West China HospitalSichuan UniversityChengduSichuan 610041China Department of Neurology Baotou Central HospitalBaotouInner Mongolia 014040China Department of Neurology Beijing Friendship HospitalCapital Medical UniversityBeijing 100000China Department of Neurology Beijing Tian Tan HospitalCapital Medical UniversityBeijing 100050China Department of Neurology Tianjin Medical University General HospitalTianjin 300052China Department of Neurology The Affiliated Hospital of Qingdao UniversityQingdaoShandong 266003China Department of Neurology Hebei General HospitalShijiazhuangHebei 050051China Department of Neurology Hua Shah Hospital of the Shanghai Fudan University Medical CollegeShanghai 200040China Department of Neurology The First Affiliated Hospital of Wenzhou Medical UniversityWenzhouZhejiang 325000China Department of Neurology Chinese People's Liberation Army General HospitalBeijing 100853China Department of Neurology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei 430030China Department of Neurology The First Affiliated Hospital of Soochow UniversitySuzhouJiangsu 215000China Department of Neurology Beijing HospitalNational Center of GerontologyBeijing 100083China Qilu Hospital of Shandong University JinanShandong 250012China Department of Neurology Beijing HospitalBeijing 100730China Department of Neurology The First Hospital of Shanxi Medical UniversityTaiyuanShanxi 030001China Department of Neurology The First Hospital of Jilin UniversityChangchunJilin 130012China Department of Neurology Xuanwu HospitalCapital Medical UniversityBeijing 100053China Department of Neurology Shanghai Chang Zheng HospitalShanghai 200003China Department of Neurology The First Hospital of China Medical UniversityShenyang

Background:Disease-modifying therapy is the standard treatment for patients with multiple sclerosis (MS)in *** primary objective of the current analysis was to assess the efficacy and safety of two teriflunomide doses (7mg and 14mg)in the subgroup of Chinese patients with relapsing MS included in the tower study. Methods:tower was a multicenter,multinational,randomized, double-blind,parallel-group (three groups),placebo-controlled *** subgroup analysis includes 148 Chinese patients randomized to receive either teriflunomide 7mg (n =51), teriflunomide 14mg (n=43),or placebo (n=54). Results:Of the 148patients in the intent-to-treat population, adjusted annualized-relapse rates were 0.63(95% confidence interval [CI]:0.44,0.92)in the placebo group,0.48(95%CI:0.33, 0.70)in the teriflunomide 7mg group,and 0.18(95%CI:0.09,0.36)in the terifltmomide 14mg group;this corresponded to a significant relative risk reduction in the teriflunomide 14mg group versus placebo (-71.2%,P =0.0012).Terifiunomide 14mg also tended to reduce 12-week confirmed disability worsening by 68.1% compared with placebo (hazard ratio:0.319,P =0.1194).There were no differences across all treatment groups in the proportion of patients with treatment-emergent adverse events (TEAEs;72.2% in the placebo group,74.5%in the teriflunomide 7mg group,and 69.8% in the teriflunomide 14mg group);corresponding proportions for serious adverse events were 11.1%,3.9%,and 11.6%,*** most frequently reported TEAEs with teriflunomide versus placebo were neutropenia,increased alanine aminotransferase,and hair thinning. Conclusions:Teriflunomide was as effective and safe in the Chinese subpopulation as it was in the overall population of patients in the tower *** has the potential to meet unmet medical needs for MS patients in China.

关键词： Chinese Patients Efficacy Phase 3 Relapsing Multiple Sclerosis Safety Teriflunomide tower

Analysis of Near-Wake Deflection Characteristics of Horizontal Axis Wind Turbine tower under Yaw State

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Energy Engineering 2021年第6期118卷 1627-1640页

作者： Zhen Liu Jianwen Wang Fuzhong Bai Caifeng Wen Yunchao Du School of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot010051China Key Laboratory of Wind Energy and Solar Energy Utilization Technology Ministry of EducationInner Mongolia University of TechnologyHohhot010051China School of Mechanical Engineering Inner Mongolia University of TechnologyHohhot010051China

The yaw of the horizontal axis wind turbine results in the deflection of the wake flow field of the *** reasonable layout of wind farm can reduce the power loss of the downstream wind turbine generators due to the blocking effect of the upstream wake flow and increase the output power of the whole wind ***,there is still much space for further *** this paper,experimental research is conducted on the near-wake deflection characteristics of wind turbine tower under yaw state,expecting the effect of throwing away a brick in order to get a *** the low-turbulence wind tunnel test,regarding the most unfavorable position where the rotating blades coincide with the tower,Particle image velocimetry(PIV)technology is used to test the instantaneous velocity field and output power and analyze experimental data at four different yaw angles,different inflow velocities and ***,in order to quantitatively analyze the laws on wake deflection,the radon transformation is used to analyze the velocity contour for calculating the wake direction angle,and the results show high *** comprehensive experimental results indicate that the near-wake flow field of the tower obviously deflects towards a side in the horizontal *** the increase of the yaw angle,the deflection angle of the wake flow field further increases,and the recovery of wake velocity *** closer to the blade root,the more complex the flow is,and the influence of the blade on the near wake of the tower is gradually *** change laws on the wake direction angle with the yaw angle and the blade spanwise direction are *** experiment in this paper can provide guidance for layout optimization of wind farm,and the obtained data can provide a scientific basis for the research on performance prediction of horizontal axis wind turbine.

关键词： Horizontal axis wind turbine yaw tower near-wake

The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line

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Research in Cold and Arid Regions 2019年第1期11卷 13-20页

作者： YanLi Xie QiHao Yu YanHui You ZhongQiu Zhang TingTao Gou State Grid Qinghai Electric Power Research Institute State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-environment and Resources Chinese Academy of Sciences

After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.

关键词： Qinghai-Tibet Power Transmission line tower foundation ground temperature change characteristic trend