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Distribution of background equivalent static wind load on high-rise buildings

Jianguo ZHANG , Ming GU ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 241-248 doi: 10.1007/s11709-009-0036-z

摘要： In this paper, the along-wind and cross-wind fluctuating load distributions along the height of high-rise buildings and their correlations are obtained through simultaneous pressure measurements in a wind tunnel. Some typical methods proposed in some relative literatures, i.e., load-response correlation (LRC), and quasi-mean load (QML) and gust load envelope (GLE) methods, are verified in terms of their accuracy in describing the background equivalent static wind load distribution on high-rise buildings. Based on the results, formulae of the distribution of background equivalent static load on high-rise buildings with typical shapes are put forward. It is shown that these formulae are of high accuracy and practical use.

关键词： high-rise buildings     along-wind     cross-wind     background equivalent static wind load     close formulae    

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Influence of core stiffness on the behavior of tall timber buildings subjected to wind loads

Zhouyan XIA, Jan-Willem G. VAN DE KUILEN, Andrea POLASTRI, Ario CECCOTTI, Minjuan HE

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 213-226 doi: 10.1007/s11709-021-0692-1

摘要： This study analyzes the feasibility of the use of cross-laminated timber (CLT) as a load-bearing structural element in a 40-story building based on Chinese design requirements. The proposed design of the high-rise concrete–CLT building utilizes the core–outrigger system. Concrete is used for the central core and outriggers, and CLT is used for the rest of the structure of the building. Finite element models with different types of connections were developed using SAP2000 to analyze the lateral behavior of the building under wind action. The finite element models with rigid connections deduce the wind load distributions on individual structural elements, which determine the total number and the stiffness of fasteners of the CLT panels. Accordingly, spring links with equivalent stiffness that simulate the mechanical fasteners were employed in SAP2000. The results indicate that CLT increases the lateral flexibility of the building. A closed concrete core was substituted by two half cores to measure the requirement of the maximum lateral deflection. However, the acceleration at the building top still exceeded the limitation prescribed in Chinese Code JGJ 3–2010 owing to the lightweight of CLT and decreased stiffness of the hybrid building. To restrict this top acceleration within the limit, further approaches to increase the stiffness in the weak direction of the building are required. Methods such as the modification of the floor layout, increase in the thickness of walls, and addition of extra damping capacity should be considered and verified in the future.

关键词： cross-laminated timber     tall timber buildings     finite element analysis     horizontal deflection     top acceleration    

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Methods and applications of DEA cross-efficiency: Review and future perspectives

Jie WU, Jiasen SUN, Liang LIANG

《工程管理前沿（英文）》 2021年 第8卷 第2期   页码 199-211 doi: 10.1007/s42524-020-0133-1

摘要： The field of engineering management usually involves evaluation issues, such as program selection, team performance evaluation, technology selection, and supplier evaluation. The traditional self-evaluation data envelopment analysis (DEA) method usually exaggerates the effects of several inputs or outputs of the evaluated decision-making unit (DMU), resulting in unrealistic results. To address this problem, scholars have proposed the cross-efficiency evaluation (CREE) method. Compared with the DEA method, CREE can rank DMUs more completely by using reasonable weights. With the extensive application of this technique, several problems, such as non-unique weights and non-Pareto optimal results, have arisen in CREE methods. Therefore, the improvement of CREE has attracted the attention of many scholars. This paper reviews the theory and applications of CREE, including the non-uniqueness problem, the aggregation of cross-efficiency data, and applications in engineering management. It also discusses the directions for future research on CREE.

关键词： cross-efficiency evaluation     efficiency     secondary goal model     aggregation     review    

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Prevalence and determinations of physical inactivity among public hospital employees in Shanghai, China: a cross-sectional

null

《医学前沿（英文）》 2015年 第9卷 第1期   页码 100-107 doi: 10.1007/s11684-014-0372-9

摘要：

This study aims to explore the prevalence and determinations of physical inactivity among hospital employees in Shanghai, China. A cross-sectional study of 4612 employees aged 19 to 68 years was conducted through stratified cluster sampling from different classes of Shanghai hospitals in 2011. The total physical activity was evaluated using the metabolic equivalent according to the Global Physical Activity Questionnaire. Among the participants, 38.5%, 32.3%, and 64.6% of the employees are inactive at work, commuting, and taking leisure time, respectively. Up to 41.8% of the men and 37.8% of the women (P = 0.012) are physically inactive. When the age and educational level are adjusted, male doctors and medical technicians show a higher percentage of physical inactivity than male workers in logistics (P = 0.001). Among females, employees who are working in second- and third-class hospitals show a higher proportion of physical inactivity than those who are working in community health care centers. Logistic regression analyses show that the odds ratios (ORs) of leisure-time physical inactivity associated with the intensity of physical activity at work are 2.259, 2.897, and 4.266 for men (P<0.001) and 2.456, 3.259, and 3.587 for women (P<0.001), respectively. The time during commuting activities is significantly associated with leisure-time physical inactivity in either sex (OR= 2.116 for men and 2.173 for women, P<0.001). Hospital employees, particularly doctors and medical technicians, show a higher proportion of physical inactivity than other inhabitants in Shanghai. The time and intensity of activity at work and commuting are associated with leisure-time activities.

关键词： prevalence     determination     employee     public hospital     cross-sectional study     physical inactivity    

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River Chief System (RCS): An experiment on cross-sectoral coordination of watershed governance

Longfei Wang, Jiaxin Tong, Yi Li

《环境科学与工程前沿（英文）》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1157-9

摘要：

The trans-regional characteristics of watershed governance produce more problems beyond the capacity of each individual water-related department, leading to the fragmentation of watershed management. The River Chief System (RCS) has experienced swift developments over the past decade in China by appointing the local government heads as river chiefs. RCS works efficiently in the short-term due to its superiority in the inclusion of clear responsibility, authority, and multi-sectoral collaboration. However, the characteristics of the authority-based vertical coordination of the hierarchical system remain unchanged, and therefore the problems of organizational logic and the responsibility dilemma still exist. Tasks including perfecting of laws, integrated watershed management, and public participation still need to be completed. RCS reflects the routine and characteristics of the migration of national governance, and as such provides new insights for other developing countries in the design of river management systems.

关键词： River Chief System     Watershed governance     Cross-sectoral coordination     Environmental protection    

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Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Pinting ZHANG, Shuhong HUANG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 419-434 doi: 10.1007/s11708-011-0166-6

摘要： Aeroelasticity has become a critical issue for Multi-Megawatt wind turbine due to the longer and more flexible blade. In this paper, the development of aeroelasticity and aeroelastic codes for wind turbine is reviewed and the aeroelastic models for wind turbine blade are described, based on which, the current research focuses for large scale wind turbine are discussed, including instability problems for onshore and offshore wind turbines, effects of complex inflow, nonlinear effects of large blade deflection, smart structure technologies, and aerohydroelasticity. Finally, the future development of aeroelastic code for large scale wind turbine: aeroservoelasticity and smart rotor control; nonlinear aeroelasticity due to large blade deflection; full-scale 3D computational fluid dynamics (CFD) solution for dynamics; and aerohydroelasticity are presented.

关键词： wind turbine     aeroelasticity     aeroelastic code    

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Air bearing center cross gap of neutron stress spectrometer sample table support system

Yang LI,Yunxin WU,Hai GONG,Xiaolei FENG

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 403-411 doi: 10.1007/s11465-016-0405-y

摘要：

A support system is the main load-bearing component of sample table for neutron stress spectrometer, and air bearing is an important element of a support system. The neutron stress spectrometer sample table was introduced, and the scheme for air bearing combination was selected. To study the performance of air bearing center cross gap, finite element models (FEMs) were established based on air motion and Reynolds equations, effects of air supply pressure, and gap parameters on the overturning moment and bearing capacity of air bearing center cross gap were analyzed. Results indicate that the width, depth, and height differences of the marble floor gap played important roles in the performance of the air bearing. When gap width is lesser than 1 mm and gap depth is lower than 0.4 mm, bearing capacity and overturning moment would vary rapidly with the variation of the width and depth. A gap height difference results in the bearing capacity dropping rapidly. The FEM results agree well with experimental results. Further, findings of the study could guide the design of the support system and marble floor.

关键词： neutron stress spectrometer     sample table     support system     air bearing     center cross gap     simulation     experiment    

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Power fluctuation and power loss of wind turbines due to wind shear and tower shadow

Binrong WEN, Sha WEI, Kexiang WEI, Wenxian YANG, Zhike PENG, Fulei CHU

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 321-332 doi: 10.1007/s11465-017-0434-1

摘要：

The magnitude and stability of power output are two key indices of wind turbines. This study investigates the effects of wind shear and tower shadow on power output in terms of power fluctuation and power loss to estimate the capacity and quality of the power generated by a wind turbine. First, wind speed models, particularly the wind shear model and the tower shadow model, are described in detail. The widely accepted tower shadow model is modified in view of the cone-shaped towers of modern large-scale wind turbines. Power fluctuation and power loss due to wind shear and tower shadow are analyzed by performing theoretical calculations and case analysis within the framework of a modified version of blade element momentum theory. Results indicate that power fluctuation is mainly caused by tower shadow, whereas power loss is primarily induced by wind shear. Under steady wind conditions, power loss can be divided into wind farm loss and rotor loss. Wind farm loss is constant at 3α(3α−1)R2/(8H2). By contrast, rotor loss is strongly influenced by the wind turbine control strategies and wind speed. That is, when the wind speed is measured in a region where a variable-speed controller works, the rotor loss stabilizes around zero, but when the wind speed is measured in a region where the blade pitch controller works, the rotor loss increases as the wind speed intensifies. The results of this study can serve as a reference for accurate power estimation and strategy development to mitigate the fluctuations in aerodynamic loads and power output due to wind shear and tower shadow.

关键词： wind turbine     wind shear     tower shadow     power fluctuation     power loss    

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Assessment of wind energy potential in Gaza Strip

Juma Yousuf ALAYDI

《能源前沿（英文）》 2011年 第5卷 第3期   页码 297-304 doi: 10.1007/s11708-010-0134-6

摘要： The analysis of collected wind data at two sites in the Gaza Strip, namely, Gaza City and Gaza International Airport in Rafah city, is presented. The two sites are candidates for remote area wind energy applications. The purpose of this paper is to present the results of the assessment of wind energy potential in the Gaza Strip in order to evaluate the wind regimes for installing wind energy conversion systems for power generation. The data on wind speed, direction and frequency distribution are used to analyze wind energy characteristics and availability at some stations in the Gaza Strip. The vertical extrapolation was based on the power-law expression, and the wind energy and potential have been estimated at the wind turbine hub height of approximately 50 m. Furthermore, the values of the Weibull parameters and are determined from summary statistics of wind resource. Consequently, the wind power is estimated by adoption of the Weibull distribution expression. Based on the results of this paper, sites are recommended for wind energy exploitation in the Gaza Strip.

关键词： wind data     wind resource assessment     wind power density     wind energy     the Weibull distribution and Weibull parameters    

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RESPONSE OF WHEAT COMPOSITE CROSS POPULATIONS TO DISEASE AND CLIMATE VARIATION OVER 13 GENERATIONS

《农业科学与工程前沿（英文）》 2021年 第8卷 第3期   页码 400-415 doi: 10.15302/J-FASE-2021394

摘要：

Since the F5 (2005), three winter wheat composite cross populations (CCPs) based on germplasm specifically suitable for low-input conditions were subjected to natural selection under organic and conventional management. In the F6, each CCP was divided into two parallel populations (12 CCPs in total) and maintained continuously until 2018. Commonly used modern cultivars with different disease susceptibilities were grown alongside to assess the agronomic performance of the CCPs. The organically managed CCPs were comparable in yield and foliar disease resistance to two continuously used reference cultivars, Achat and Capo. In contrast, under conventional management the cv. Capo outyielded the CCPs (Achat was not tested), highlighting the importance of parental cultivar choice for specific management systems. The CCPs were found to be moderately resistant to brown rust and even to the newly emerged stripe rust races prevalent in Europe since 2011. Differences between the CCPs were mainly due to parental genetic background and were significant in the first five generations, but were no longer so in the last five generations. In addition, these differences tended to vary depending on the experimental year and the environmental stresses present. In conclusion, the CCPs despite being derived from older cultivars are able to compete with more recently released reference cultivars under organic farming practices and represent a dynamic germplasm resource.

 

关键词： evolutionary breeding     heterogeneous crop population     management system    

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Quality and efficiency improvement technology for five megawatt offshore wind turbines and its application

Huali HAN

《工程管理前沿（英文）》 2020年 第7卷 第4期   页码 618-621 doi: 10.1007/s42524-020-0142-0

关键词： renewable energy     megawatt offshore wind turbine     technology-driven     quality improvement    

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Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 78-98 doi: 10.1007/s11709-022-0936-8

摘要： For localized fires, it is necessary to consider the thermal and mechanical responses of building elements subject to uneven heating under the influence of wind. In this paper, the thermomechanical phenomena experienced by a ceiling jet and I-beam in a structural fire were simulated. Instead of applying the concept of adiabatic surface temperature (AST) to achieve fluid–structure coupling, this paper proposes a new computational fluid dynamics–finite element method numerical simulation that combines wind, fire, thermal, and structural analyses. First, to analyze the velocity and temperature distributions, the results of the numerical model and experiment were compared in windless conditions, showing good agreement. Vortices were found in the local area formed by the upper and lower flanges of the I-beam and the web, generating a local high-temperature zone and enhancing the heat transfer of convection. In an incoming-flow scenario, the flame was blown askew significantly; the wall temperature was bimodally distributed in the axial direction. The first temperature peak was mainly caused by radiative heat transfer, while the second resulted from convective heat transfer. In terms of mechanical response, the yield strength degradation in the highest-temperature region in windless conditions was found to be significant, thus explaining the stress distribution of steel beams in the fire field. The mechanical response of the overall elements considering the incoming flows was essentially elastic.

关键词： CFD–FEM coupling     steel beam     wind     ceiling jet     numerical heat transfer    

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Evaluation of the wind energy potential of two south west sites in Nigeria

Olaleye M. AMOO

《能源前沿（英文）》 2012年 第6卷 第3期   页码 237-246 doi: 10.1007/s11708-012-0201-2

摘要： Wind resource assessment is a crucial first step in gauging the potential of a site to produce energy from wind turbines. In this paper, the wind energy potential of Abeokuta (07°03'N, 03°19'E) and Ijebu-Ode (06°47'N, 03°58'E), two south west sites in Nigeria were examined. Twenty years (1990–2010) of monthly mean wind data from a 10 m height were subjected to two-parameter Weibull analysis and other statistical analyses. The results show that the average annual mean wind speed variation for Abeokuta ranges from 2.2 to 5.0 m/s. For Ijebu-Ode, it ranges from 2.0 to 5.0 m/s. The wind power density variation based on the Weibull analysis ranges from 4.26 to 24.51 W/m for Abeokuta and from 8.54 to 76.46 W/m for Ijebu-Ode. Ijebu-Ode was found to be the better of the two sites in terms of annual variation of mean wind speed.

关键词： wind potential     wind speed     wind power density     wind gust     turbulence intensity     Nigeria    

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Condition monitoring of a wind turbine generator using a standalone wind turbine emulator

Himani,Ratna DAHIYA

《能源前沿（英文）》 2016年 第10卷 第3期   页码 286-297 doi: 10.1007/s11708-016-0419-5

摘要： The intend of this paper is to give a description of the realization of a low-cost wind turbine emulator(WTE) with open source technology from graze required for the condition monitoring to diagnose rotor and stator faults in a wind turbine generator (WTG). The WTE comprises of a 2.5 kW DC motor coupled with a 1 kW squirrel-cage induction machine. This paper provides a detailed overview of the hardware and software used along with the WTE control strategies such as MPPT and pitch control. The emulator reproduces dynamic characteristics both under step variations and arbitrary variation in the wind speed of a typical wind turbine (WT) of a wind energy conversion system (WECS). The usefulness of the setup has been benchmarked with previously verified WT test rigs made at the University of Manchester and Durham University in UK. Considering the fact that the rotor blades and electric subassemblies direct drive WTs are most susceptible to damage in practice, generator winding faults and rotor unbalance have been introduced and investigated using the terminal voltage and generated current. This wind turbine emulator (WTE) can be reconfigured or analyzed for condition monitoring without the need for real WTs.

关键词： condition monitoring (CM)     wind turbine emulator (WTE)     wind turbine generator (WTG)     maximum power point tracking (MPPT)     tip speed ratio (TSR)     rotor faults     stator faults    

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Technical innovation for Sanyang Road Cross-river Tunnel Project

Yu ZHONG

《工程管理前沿（英文）》 2018年 第5卷 第3期   页码 411-415 doi: 10.15302/J-FEM-2018206

摘要：

关键词： valign=     top     class=     J_zhaiyao    

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标题 作者 时间 类型 操作

Distribution of background equivalent static wind load on high-rise buildings

Jianguo ZHANG , Ming GU ,

期刊论文

Influence of core stiffness on the behavior of tall timber buildings subjected to wind loads

Zhouyan XIA, Jan-Willem G. VAN DE KUILEN, Andrea POLASTRI, Ario CECCOTTI, Minjuan HE

期刊论文

Methods and applications of DEA cross-efficiency: Review and future perspectives

Jie WU, Jiasen SUN, Liang LIANG

期刊论文

Prevalence and determinations of physical inactivity among public hospital employees in Shanghai, China: a cross-sectional

null

期刊论文

River Chief System (RCS): An experiment on cross-sectoral coordination of watershed governance

Longfei Wang, Jiaxin Tong, Yi Li

期刊论文

Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Pinting ZHANG, Shuhong HUANG

期刊论文

Air bearing center cross gap of neutron stress spectrometer sample table support system

Yang LI,Yunxin WU,Hai GONG,Xiaolei FENG

期刊论文

Power fluctuation and power loss of wind turbines due to wind shear and tower shadow

Binrong WEN, Sha WEI, Kexiang WEI, Wenxian YANG, Zhike PENG, Fulei CHU

期刊论文

Assessment of wind energy potential in Gaza Strip

Juma Yousuf ALAYDI

期刊论文

RESPONSE OF WHEAT COMPOSITE CROSS POPULATIONS TO DISEASE AND CLIMATE VARIATION OVER 13 GENERATIONS

期刊论文

Quality and efficiency improvement technology for five megawatt offshore wind turbines and its application

Huali HAN

期刊论文

Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

期刊论文

Evaluation of the wind energy potential of two south west sites in Nigeria

Olaleye M. AMOO

期刊论文

Condition monitoring of a wind turbine generator using a standalone wind turbine emulator

Himani,Ratna DAHIYA

期刊论文

Technical innovation for Sanyang Road Cross-river Tunnel Project

Yu ZHONG

期刊论文