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Choosing configurations of transmission line tower grounding by back flashover probability value

Dmitry KUKLIN

《能源前沿（英文）》 2016年第10卷第2期页码 213-226 doi: 10.1007/s11708-016-0398-6

摘要： There is a considerable number of works devoted to electrical characteristics of grounding. These characteristics are important in general. However, in application to grounding of transmission line towers they are not enough to determine what grounding construction is preferable in some particular case, because these characteristics are calculated or measured apart from the grounded object, and only limited number of current (or voltage) source waveforms is used. This paper indicates reasons in favor of the fact that to choose the optimum design of grounding, the calculation model should include the tower as it is. The probability of back flashover, which provides both qualitative and quantitative estimate of the grounding structure efficiency, can be taken as the criterion for the grounding design. The insulation flashover probability is calculated on the basis of engineering method, which evaluates breakdown strength of insulation for nonstandard waveshapes, and probability data on lightning currents. Different approaches are examined for identifying the back flashover probability, as not only amplitudes but also other parameters can be taken into account. Finite-difference time-domain method is used for calculations of transients. It is found that lightning current waveform can greatly influence calculated back flashover probability value.

关键词： grounding transmission line tower back flashover probability FDTD method

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泰州大桥钢中塔线形控制误差调整方法

张向群,王琳,游新鹏

《中国工程科学》 2012年第14卷第5期页码 29-32

摘要：

泰州大桥钢中塔首次采用纵向“人”字形、横向门式框架结构，采用节段预制-现场安装的方法安装钢塔。建立针对复杂钢塔的全过程施工控制体系，在制造阶段对节段形态以及制造线形进行精确测控的基础上，在安装阶段根据实际安装误差情况确定预先设置调节缝的调整量，达到对钢塔线形误差调整的目的。现场实施结果表明，泰州大桥中间钢塔的线形控制效果良好，最终线形各项精度均优于设计要求。

关键词：泰州大桥中间钢塔线形控制误差调整

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全尺寸交流500 kV输电杆塔复合横担的雷电闪络特性 Article

王乾, 梁曦东, 沈余峰, 刘书明, 左周, 高岩峰

《工程（英文）》 2023年第23卷第4期页码 130-137 doi: 10.1016/j.eng.2021.09.021

摘要：

架空输电线路（OTL）一直以来都是电力传输的主要方式。随着输电电压和输电容量的迅速提高，输电杆塔的尺寸也随之增加，造成土地资源的大量占用。考虑到线路复合绝缘子的优异性能，复合横担有望成为这一问题的解决方案。在本文中，作者制备了一个安装有复合横担的全尺寸交流（AC）500 kV输电杆塔，并施加了不同极性的雷电过电压。借助高速相机记录了流注-先导放电的过程，确认了闪络的主要路径。通过测量闪络电压并根据空气密度和湿度对结果进行修正，证实了放电的极性效应。继而，根据杆塔结构和闪络特性计算了杆塔的耐雷水平。基于全尺寸试验的结果与分析，确认了复合横担的可行性，并提出了结构优化方案。

关键词：复合横担输电杆塔雷电闪络流注放电耐雷水平

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用于超快电子器件的全通型波导 Article

Desong Wang, Ke Wu

《工程（英文）》 2023年第30卷第11期页码 49-54 doi: 10.1016/j.eng.2023.04.005

摘要：

Ultrashort pulse transmission has been recognized as a primary problem that fundamentally hinders the development of ultrafast electronics beyond the current nanosecond timescale. This requires a transmission line or waveguide that exhibits an all-pass frequency behavior for the transmitted ultrashort pulse signals. However, this type of waveguiding structure has not yet been practically developed; groundbreaking innovations and advances in signal transmission technology are urgently required to address this scenario. Herein, we present a synthesized all-pass waveguide that demonstrates record guided-wave controlling capabilities, including eigenmode reshaping, polarization rotation, loss reduction, and dispersion improvement. We experimentally developed two waveguides for use in ultrabroad frequency ranges (direct current (DC)-to-millimeter-wave and DC-to-terahertz). Our results suggest that the waveguides can efficiently transmit picosecond electrical pulses while maintaining signal integrity. This waveguide technology is an important breakthrough in the evolution of ultrafast electronics, providing a path towards frequency-engineered ultrashort pulses for low-loss and low-dispersion transmissions.

关键词： All-pass waveguide Ultrashort pulse Picosecond transmission Ultrafast electronics Terahertz technology Mode-selective transmission line

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Safety and serviceability assessment for high-rise tower crane to turbulent winds

Zhi SUN, Nin HOU, Haifan XIANG

《结构与土木工程前沿（英文）》 2009年第3卷第1期页码 18-24 doi: 10.1007/s11709-009-0009-2

摘要： Tower cranes are commonly used facilities for the construction of high-rise structures. To ensure their workability, it is very important to analyze their response and evaluate their condition under extreme conditions. This paper proposes a general scheme for safety and serviceability assessment of high-rise tower crane to turbulent winds based on time domain buffeting response analysis. Spatially correlated wind velocity field at the location of the tower crane was first simulated using an algorithm for generating the time domain samples of a stationary, multivariate stochastic process according to some prescribed spectral density matrix. The buffeting forces applied to the structure were computed according to the above-simulated wind velocity fluctuations and the lift, drag, and moment coefficients obtained from a CFD computation. Those spatially correlated loads were then fed into a well calibrated finite element model and the nonlinear time history analysis was conducted to compute structural buffeting response. Compared with structural on-site response measurement, the computed response using the proposed method has good precision. The proposed method is then adopted for analyzing the buffeting response of an in-use tower crane under the design wind speed and the maximum operational wind speed for safety and serviceability assessment.

关键词： tower crane buffeting response wind velocity modeling

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Practice and Experience of Canton Tower Project Management

Rong-hua Yi

《工程管理前沿（英文）》 2016年第3卷第1期页码 74-79 doi: 10.15302/J-FEM-2016013

摘要： This paper presents a brief introduction about the preliminary consulting and tender agent of Canton Tower, the basic situation of the whole-process supervision on the construction site, and a general summary of the Canton Tower project management. What’s more, the author suggests that some guidelines be formed for supervision enterprises involved in large-scale project management.

关键词： Canton Tower consultation tender agent whole-process supervision

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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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Impacts of solar multiple on the performance of direct steam generation solar power tower plant with

Yan LUO, Xiaoze DU, Lijun YANG, Chao XU, Muhammad AMJAD

《能源前沿（英文）》 2017年第11卷第4期页码 461-471 doi: 10.1007/s11708-017-0503-5

摘要： Solar multiple (SM) and thermal storage capacity are two key design parameters for revealing the performance of direct steam generation (DSG) solar power tower plant. In the case of settled land area, SM and thermal storage capacity can be optimized to obtain the minimum levelized cost of electricity (LCOE) by adjusting the power generation output. Taking the dual-receiver DSG solar power tower plant with a given size of solar field equivalent electricity of 100 MW in Sevilla as a reference case, the minimum LCOE is 21.77 ￠/kWh with an SM of 1.7 and a thermal storage capacity of 3 h. Besides Sevilla, two other sites are also introduced to discuss the influence of annual DNI. When compared with the case of Sevilla, the minimum LCOE and optimal SM of the San Jose site change just slightly, while the minimum LCOE of the Bishop site decreases by 32.8% and the optimal SM is reduced to 1.3. The influence of the size of solar field equivalent electricity is studied as well. The minimum LCOE decreases with the size of solar field, while the optimal SM and thermal storage capacity still remain unchanged. In addition, the sensitivity of different investment in sub-system is investigated. In terms of optimal SM and thermal storage capacity, they can decrease with the cost of thermal storage system but increase with the cost of power generation unit.

关键词： direct steam generation solar power tower solar multiple thermal energy storage capacity levelized cost of electricity (LCOE)

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Acoustic fault signal extraction via the line-defect phononic crystals

《机械工程前沿（英文）》 2022年第17卷第1期页码 10-10 doi: 10.1007/s11465-021-0666-y

摘要： Rotating machine fault signal extraction becomes increasingly important in practical engineering applications. However, fault signals with low signal-to-noise ratios (SNRs) are difficult to extract, especially at the early stage of fault diagnosis. In this paper, 2D line-defect phononic crystals (PCs) consisting of periodic acrylic tubes with slit are proposed for weak signal detection. The defect band, namely, the formed resonance band of line-defect PCs enables the incident acoustic wave at the resonance frequency to be trapped and enhanced at the resonance cavity. The noise can be filtered by the band gap. As a result, fault signals with high SNRs can be obtained for fault feature extraction. The effectiveness of weak harmonic and periodic impulse signal detection via line-defect PCs are investigated in numerical and experimental studies. All the numerical and experimental results indicate that line-defect PCs can be well used for extracting weak harmonic and periodic impulse signals. This work will provide potential for extracting weak signals in many practical engineering applications.

关键词： phononic crystals line-defect fault signal extraction acoustic enhancement

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泰州大桥——世界首座千米级三塔悬索桥

钟建驰

《中国工程科学》 2010年第12卷第4期页码 4-8

摘要：

2007年12月开工建设的泰州大桥位于江苏省中部，连接泰州与镇江，为世界首座千米级三塔连跨悬索桥，同时中塔采用世界首个纵向人字型钢塔，中塔基础采用世界上入土最深的水中沉井基础。为了建造这项宏伟的工程，针对众多技术挑战，建设者采取了一系列的创新技术：三塔悬索桥的设计技术，江中大型深井的定位着床、封底技术，人字型钢中塔的钢混结合连接技术、超厚钢板的焊接加工技术以及钢中塔异型节段的精确加工与控制技术等。

关键词：三塔悬索桥创新设计水中沉井人字型钢塔

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螺旋结构冷却塔的塔板设计方法

黄锐

《中国工程科学》 2008年第10卷第11期页码 43-46

摘要：

针对冷却塔中螺旋结构类型的气液交换塔，提出其内部螺旋塔板形状的设计方法，包括塔壁上外螺旋线和塔中心轴管上内螺旋线的位置确定，以及两线之间螺旋曲面板在平面上的拓扑尺寸。通过塔的几何参数确定螺旋曲面板设计的关键参数，可实现扭曲状塔板与塔壁及内轴的准确配合。

关键词：冷却塔塔板设计螺旋曲面拓扑

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Calculations of narrow-band transimissities and the Planck mean absorption coefficients of real gases using line-by-line

Huaqiang CHU, Mingyan GU, Huaichun ZHOU, Fengshan LIU

《能源前沿（英文）》 2014年第8卷第1期页码 41-48 doi: 10.1007/s11708-013-0292-4

摘要： Narrow-band transmissivities in the spectral range of 150 to 9300 cm and at a uniform resolution of 25 cm were calculated using the statistical narrow-band (SNB) model with the band parameters of Soufiani and Taine, the more recent parameters of André and Vaillon, and the line-by-line (LBL) method along with the HITEMP-2010 spectroscopic database. Calculations of narrow-band transmissivity were conducted for gas columns of different lengths and containing different isothermal and non-isothermal CO -H O-N mixtures at 1 atm. Narrow-band transmissivities calculated by the SNB model are in large relative error at many bands. The more recent SNB model parameters of André and Vaillon are more accurate than the earlier parameters of Soufiani and Taine. The Planck mean absorption coefficients of CO , H O, CO, and CH in the temperature range of 300 to 2500 K were calculated using the LBL method and different versions of the high resolution transmission (HITRAN) and high-temperature spectroscopic absorption parameters (HITEMP) spectroscopic databases. The SNB model was also used to calculate the Planck mean absorption coefficients of these four radiating gases. The LBL results of the Planck mean absorption coefficient were compared with the classical results of Tien and those from the SNB model.

关键词： transimissity HITEMP HITRAN Planck mean absorption coefficients

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泰州大桥中间塔鞍座抗滑安全评估

阮欣,阮静,陈艾荣,郭济

《中国工程科学》 2012年第14卷第5期页码 71-74

摘要：

在分析鞍座抗滑机理的基础上，建立了基于最大静摩擦系数的三塔悬索桥中间塔鞍座抗滑基本评估模型,并发展了多种鞍座抗滑评估方法。包括基于目前使用的设计规范评估鞍座抗滑安全的确定性方法；基于静态车辆数据合成随机车流，并利用Rice公式外推其荷载效应极值，进而研究鞍座抗滑安全性能的评估方法；以及基于车辆荷载效应和抗力概率模型的鞍座抗滑概率评估方法。用上述三种方法分别对泰州大桥鞍座抗滑安全性进行全面评估，表明泰州大桥中塔鞍座抗滑安全可靠。

关键词：三塔两跨悬索桥中间塔鞍座确定性评估概率评估

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Recent transmission of Mycobacterium tuberculosis in China: the implication of molecular epidemiology

null

《医学前沿（英文）》 2018年第12卷第1期页码 76-83 doi: 10.1007/s11684-017-0609-5

摘要：

Tuberculosis (TB) has remained an ongoing concern in China. The national scale-up of the Directly Observed Treatment, Short Course (DOTS) program has accelerated the fight against TB in China. Nevertheless, many challenges still remain, including the spread of drug-resistant strains, high disease burden in rural areas, and enormous rural-to-urban migrations. Whether incident active TB represents recent transmission or endogenous reactivation has helped to prioritize the strategies for TB control. Evidence from molecular epidemiology studies has delineated the recent transmission of ( ) strains in many settings. However, the transmission patterns of TB in most areas of China are still not clear. Studies carried out to date could not capture the real burden of recent transmission of the disease in China because of the retrospective study design, incomplete sampling, and use of low-resolution genotyping methods. We reviewed the implementations of molecular epidemiology of TB in China, the estimated disease burden due to recent transmission of strains, the primary transmission of drug-resistant TB, and the evaluation of a feasible genotyping method of strains in circulation.

关键词： tuberculosis recent transmission molecular epidemiology China

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Pareto lexicographic α-robust approach and its application in robust multi objective assembly line balancing

null

《机械工程前沿（英文）》 2014年第9卷第3期页码 257-264 doi: 10.1007/s11465-014-0294-x

摘要：

Robustness in most of the literature is associated with min-max or min-max regret criteria. However, these criteria of robustness are conservative and therefore recently new criteria called, lexicographic α-robust method has been introduced in literature which defines the robust solution as a set of solutions whose quality or jth largest cost is not worse than the best possible jth largest cost in all scenarios. These criteria might be significant for robust optimization of single objective optimization problems. However, in real optimization problems, two or more than two conflicting objectives are desired to optimize concurrently and solution of multi objective optimization problems exists in the form of a set of solutions called Pareto solutions and from these solutions it might be difficult to decide which Pareto solution can satisfy min-max, min-max regret or lexicographic α-robust criteria by considering multiple objectives simultaneously. Therefore, lexicographic α-robust method which is a recently introduced method in literature is extended in the current research for Pareto solutions. The proposed method called Pareto lexicographic α-robust approach can define Pareto lexicographic α-robust solutions from different scenarios by considering multiple objectives simultaneously. A simple example and an application of the proposed method on a simple problem of multi objective optimization of simple assembly line balancing problem with task time uncertainty is presented to get their robust solutions. The presented method can be significant to implement on different multi objective robust optimization problems containing uncertainty.

关键词： Pareto lexicographic α-robust assembly line balancing