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Adaptability evolution of financing systems of mega projects

Xue YAN, Longmiao GAO, Huimin LIU

《工程管理前沿（英文）》 2021年第8卷第2期页码 258-270 doi: 10.1007/s42524-019-0066-8

摘要： Mega projects require large funding, which often reaches tens or even hundreds of billions of yuan. In the state-oriented financing system, the huge fund gap has generally become an important factor restricting the development of mega projects worldwide. Since the 1980s, China’s long-span bridge projects have developed rapidly as typical mega projects as their financing systems have also undergone a series of changes and shown a high adaptability to complexity. However, the existing literature based on the perspective of evolution lacks focus on the complexity of mega project financing systems and its causes. Therefore, the complexity of the financing methods employed in the financing systems for China’s long-span bridges is analyzed in this work from the dimensions of time and regions through investigation and interviews. On the basis of the results and complex adaptive systems theory, the causes of the complexity are further explored in terms of the clustering effects of financing subjects and the deep uncertainty of financing environments. Then, the evolution rules of financing systems of mega projects are established from the aspect of financing subjects, financing environments, and financing methods. The research results can enrich decision-makers’ understanding of the essential attributes and formation mechanism of the financing systems of mega projects and provide powerful support for decision-making in financing.

关键词： adaptability evolution financing methods long-span bridges in China mega projects

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Enhancing the terrain adaptability of a multirobot cooperative transportation system via novel connectors

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0754-2

摘要： Given limited terrain adaptability, most existing multirobot cooperative transportation systems (MRCTSs) mainly work on flat pavements, restricting their outdoor applications. The connectors’ finite deformation capability and the control strategies’ limitations are primarily responsible for this phenomenon. This study proposes a novel MRCTS based on tracked mobile robots (TMRs) to improve terrain adaptability and expand the application scenarios of MRCTSs. In structure design, we develop a novel 6-degree-of-freedom passive adaptive connector to link multiple TMRs and the transported object (the communal payload). In addition, the connector is set with sensors to measure the position and orientation of the robot with respect to the object for feedback control. In the control strategy, we present a virtual leader–physical follower collaborative paradigm. The leader robot is imaginary to describe the movement of the entire system and manage the follower robots. All the TMRs in the system act as follower robots to transport the object cooperatively. Having divided the whole control structure into the leader robot level and the follower robot level, we convert the motion control of the two kinds of robots to trajectory tracking control problems and propose a novel double closed-loop kinematics control framework. Furthermore, a control law satisfying saturation constraints is derived to ensure transportation stability. An adaptive control algorithm processes the wheelbase uncertainty of the TMR. Finally, we develop a prototype of the TMR-based MRCTS for experiments. In the trajectory tracking experiment, the developed MRCTS with the proposed control scheme can converge to the reference trajectory in the presence of initial tracking errors in a finite time. In the outdoor experiment, the proposed MRCTS consisting of four TMRs can successfully transport a payload weighing 60 kg on an uneven road with the single TMR’s maximum load limited to 15 kg. The experimental results demonstrate the effectiveness of the structural design and control strategies of the TMR-based MRCTS.

关键词： multirobot system cooperative transportation terrain adaptability trajectory tracking collaborative paradigm uneven road

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Analysis of load and adaptability of disc cutters during shield tunneling in soft–hard varied strata

《结构与土木工程前沿（英文）》 2023年第17卷第4期页码 533-545 doi: 10.1007/s11709-023-0946-1

摘要： The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process. To analyze the rotation state, cutting performance, and adaptability of disc cutters during shield tunneling in soft–hard varied strata, the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters. Additionally, the parameters of the models are modified based on laboratory disc cutter excavation test results. The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation. The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated, thus providing reference values for the starting torque of the disc cutters. A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect. The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear, rotation stagnation, cutterhead clogging, and other adverse phenomena.

关键词： shield tunneling disc cutter load laboratory excavation test numerical calculation soft–hard varied strata

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300m级面板堆石坝适应性及对策研究

马洪琪

《中国工程科学》 2011年第13卷第12期页码 4-8

摘要：

系统总结了200ｍ级面板坝建设的主要经验与教训，对４座３００ｍ级面板坝典型工程进行了分析，提出了３００ｍ级面板坝需要研究的基础科学和关键技术问题。

关键词：混凝土面板堆石坝适应性对策研究

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北京铁路地下直径线泥水盾构刀盘、刀具适应性分析

何峰,李小岗,孙善辉

《中国工程科学》 2010年第12卷第12期页码 35-40

摘要：

结合北京站至北京西站地下直径线工程实例，通过不同盾构刀盘刀具配置在砂卵石下的应用对比，重点对工程刀盘刀具改造前后对地层的适应性进行了详细的对比分析，提出了砂卵石条件下刀盘刀具配置应注意的关键问题，对类似工程有借鉴作用。

关键词：直径线泥水盾构刀盘刀具适应性

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高速铁路动车组在线路上适应性设计方法及应用

王开云,袁玄成,翟婉明

《中国工程科学》 2015年第17卷第4期页码 90-97

摘要：

基于新一代中国高速列车（动车组）关键技术的研究发展趋势和策略问题进行详细讨论和技术展望。主要内容包括：首先，介绍国际先进轨道车辆制造商在其新一代车辆开发过程中采用的先进设计技术和理念，分层次研究其各自的核心技术特点和未来其可能的技术发展趋势。其次，在国内外文献研究的基础上，结合中国高速铁路车辆发展的自身特点和实际情况，针对具体的牵引传动技术、转向架技术、车体设计技术等可能面临的核心技术难题，提出一些分析建议。最后，在综合考虑轨道车辆造型发展趋势及设计原则的基础上，根据集成设计的理论与多学科优化设计方法，针对新一代中国高速铁路动车组可能面临的重大技术挑战与策略和改进措施的研究提出一些明确的建议。总之，通过本文的初步研究，希望可以对我国高速列车未来的发展方向和趋势提出一些有益的建议。

关键词：高速铁路；线路适应性；动车组；车辆-轨道耦合动力学

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The ecological adaptability of cloned sheep to free-grazing in the Tengger Desert of Inner Mongolia,

Xinxin LI,Huijuan WANG,Guanghua SU,Zhuying WEI,Chunling BAI,Wuni-MENGHE,Yanhui HOU,Changqing YU,Shorgan BOU,Guangpeng LI

《农业科学与工程前沿（英文）》 2014年第1卷第3期页码 191-200 doi: 10.15302/J-FASE-2014029

摘要： Since the birth of the first cloned sheep, somatic cell nuclear transfer technology has been successfully used to clone a variety of mammals. Cloned livestock have no apparent health risks, and the quality and safety of the cloned animal products are similar to non-cloned animals. The social behavior and environmental adaptability of postnatal cloned animals, especially when used for grassland farm production purposes, is unknown. In the present study, the cloned Dorper sheep equipped with GPS location devices were free-grazed in a harsh natural environment similar to conditions commonly experienced by Mongolian sheep. The main findings of this research were as follows. (1) Under free-grazing conditions, the cloned sheep showed excellent climatic and ecological adaptability. In extreme temperature conditions ranging from -30 to 40°C, the cloned sheep maintained acceptable body condition and behaved as other sheep. (2) The cloned sheep quickly adapted from a herd feeding strategy to the harsh environment and quickly exhibited a grazing regimen as other free-grazing sheep. (3) The cloned sheep exhibited free-grazing patterns and social behavior as other sheep. (4) The cloned sheep in the harsh environment thrived and produced healthy lambs. Overall, the cloned Dorper sheep exhibited excellent ecological adaptation, which is an important consideration for breeding meat sheep by cloning. The Dorper sheep readily adapted to the free-grazing conditions on the Mongolian plateau grassland, which attests to their ability to withstand harsh environmental conditions.

关键词： somatic cell nuclear transfer free-grazing synchronization Dorper sheep cloned animal ecology

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Adaptability to geological faulted foundation of Hardfill dam

XIONG Kun, HE Yunlong, PENG Yunfeng

《结构与土木工程前沿（英文）》 2008年第2卷第4期页码 343-349 doi: 10.1007/s11709-008-0057-z

摘要： Hardfill dam is a new type of dam which has the advantages of low stress level and even stress distribution in a dam body, resulting in low demands to foundations. Based on 2D linear elastic and elasto-plastic calculations of gravity dam and Hardfill dam using finite element method (FEM), the stress distribution in a dam body and anti-sliding stabilization is analyzed on the geological faulted foundations with weak weathered rock and soft interlayers. It is concluded that Hardfill dams have better adaptability to geological faulted foundations than gravity dams and is more secure and economically sound.

关键词： weathered elastic geological faulted FEM gravity

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Concept and requirements of sustainable development in bridge engineering

Yaojun GE, Haifan XIANG

《结构与土木工程前沿（英文）》 2011年第5卷第4期页码 432-450 doi: 10.1007/s11709-011-0126-6

摘要： The concept of sustainability is described in this paper using a single sustainable principle, two goals of sustainable development, three dimensions of sustainable engineering, four sustainable requirements and five phases of sustainable construction. Four sustainable requirements and their practice in China are discussed in particular. The safe reliability of bridges is first compared with the events of bridge failure in China and in the rest of the world and followed by structural durability, including the cracking of concrete cable-stayed bridges, deflection of concrete girder bridges and fatigue cracks of orthotropic steel decks. With respect to functional adaptability, lateral wind action on vehicles and its improvement are introduced regarding a sea-crossing bridge located in a typhoon-prone area. The Chinese practice of using two double main span suspension bridges and a twin parallel deck cable-stayed bridge is presented in discussing the final sustainable requirement: capacity extensibility.

关键词： sustainable engineering safe reliability structural durability functional adaptability capacity extensibility

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Tuned reactive power dispatch through modified differential evolution technique

S. BISWAS (RAHA), N. CHAKRABORTY

《能源前沿（英文）》 2012年第6卷第2期页码 138-147 doi: 10.1007/s11708-012-0188-8

摘要： This paper explores the capability of modified differential evolution (MDE) technique for solving the reactive power dispatch (RPD) problem. The proposed method is based on the basic differential evolution (DE) technique with a few modifications made into it. DE is one of the strongest optimization techniques though it suffers from the problem of slow convergence while global minima appear. The proposed modifications are tried to resolve the problem. The RPD problem mainly defines loss minimization with stable voltage profile. To solve the RPD problem, the generator bus voltage, transformer tap setting and shunt capacitor placements are controlled by the MDE approach. In this paper, IEEE 14-bus and IEEE 30-bus systems are chosen for MDE implementation. The applied modification show much improved result in comparison to normal DE technique. Comparative study with other soft-computing technique including DE validates the effectiveness of the proposed method.

关键词： reactive power dispatch (RPD) modified differential evolution (MDE) differential evolution algorithm with localizations around the best vector (DELB)

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Strategic Thinking on a Revolution/an Evolution in Production and Consumption of Energy in China

Ke-chang Xie,Ke Liu

《工程管理前沿（英文）》 2014年第1卷第1期页码 30-36 doi: 10.15302/J-FEM-2014006

摘要： This article summarizes the thinking behind the call for a revolution/an evolution in China's energy production and consumption. China is still a developing country, though it has experienced fast economic growth in the past thirty years. It achieved great accomplishments surprising the world, and it is also confronted with challenges on energy supply and environmental protection. As environmental pollution becomes more and more serious, the energy challenges have become more and more complicated. With this in mind, the authors analyzed China's energy situation, China's energy supply and consumption, the world energy map, China's commitment both to improving its domestic environment and fulfilling its international obligations to control climate change. Action plans are presented to support the call for a revolution/an evolution in China's energy production and consumption as an effective assurance for China's ambitious goal of building a moderately prosperous society in all respects.

关键词： revolution evolution energy production consumption

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Polypyrrole@NiCo hybrid nanotube arrays as high performance electrocatalyst for hydrogen evolution reaction

Shenghua Ye, Gaoren Li

《化学科学与工程前沿（英文）》 2018年第12卷第3期页码 473-480 doi: 10.1007/s11705-018-1724-9

摘要：

The polypyrrole(PPy)@NiCo hybrid nanotube arrays have been successfully fabricated as a high performance electrocatalyst for hydrogen evolution reaction (HER) in alkaline solution. The strong electronic interactions between PPy and NiCo alloy are confirmed by X-ray photoelectron spectroscopy and Raman spectra. Because these interations can remarkably reduce the apparent activation energy (E_a) for HER and enhance the turnover frequency of catalysts, the electrocatalytic performance of PPy@NiCo hybrid nanotube arrays are significantly improved. The electrochemical tests show that the PPy@NiCo hybrid catalysts exhibit a low overpotential of ~186 mV at 10.0 mA·cm⁻² and a small tafel slope of 88.6 mV·deg⁻¹ for HER in the alkaline solution. The PPy@NiCo hybrid nanotubes also exhibit high catalytic activity and high stability for HER.

关键词： NiCo alloy polypyrrole hybrid nanotube electrocatalyst hydrogen evolution reaction

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Synergistic effect of V and Fe in Ni/Fe/V ternary layered double hydroxides for efficient and durable oxygen evolution

《化学科学与工程前沿（英文）》 2023年第17卷第1期页码 102-115 doi: 10.1007/s11705-022-2179-6

摘要： High-performance and stable electrocatalysts are vital for the oxygen evolution reaction (OER). Herein, via a one-pot hydrothermal method, Ni/Fe/V ternary layered double hydroxides (NiFeV-LDH) derived from Ni foam are fabricated to work as highly active and durable electrocatalysts for OER. By changing the feeding ratio of Fe and V salts, the prepared ternary hydroxides were optimized. At an Fe:V ratio of 0.5:0.5, NiFeV-LDH exhibits outstanding OER activity superior to that of the binary hydroxides, requiring overpotentials of 269 and 274 mV at 50 mA·cm^–2 in the linear sweep voltammetry and sampled current voltammetry measurements, respectively. Importantly, NiFeV-LDH shows extraordinary long-term stability (≥ 75 h) at an extremely high current density of 200 mA·cm^–2. In contrast, the binary hydroxides present quick decay at 200 mA·cm^–2 or even reduced current densities (150 and 100 mA·cm^–2). The outstanding OER performance of NiFeV-LDH benefits from the synergistic effect of V and Fe while doping the third metal into bimetallic hydroxide layers: (a) Fe plays a crucial role as the active site; (b) electron-withdrawing V stabilizes the high valence state of Fe, thus accelerating the OER process; (c) V further offers great stabilization for the formed intermediate of FeOOH, thus achieving superior durability.

关键词： oxygen evolution reaction electrocatalysts ternary layered double hydroxides long-term stability

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heterostructure grown on nickel foam as efficient and durable self-supported electrocatalysts for hydrogen evolution

《化学科学与工程前沿（英文）》 2023年第17卷第4期页码 437-448 doi: 10.1007/s11705-022-2228-1

摘要： High-performance and ultra-durable electrocatalysts are vital for hydrogen evolution reaction (HER) during water splitting. Herein, by one-pot solvothermal method, MoO_x/Ni₃S₂ spheres comprising Ni₃S₂ nanoparticles inside and oxygen-deficient amorphous MoO_x outside in situ grow on Ni foam (NF), to assembly the heterostructure composites of MoO_x/Ni₃S₂/NF. By adjusting volume ratio of the solvents of ethanol to water, the optimized MoO_x/Ni₃S₂/NF-11 exhibits the best HER performance, requiring an extremely low overpotential of 76 mV to achieve the current density of 10 mA∙cm^‒2 (η₁₀ = 76 mV) and an ultra-small Tafel slope of 46 mV∙dec^‒1 in 0.5 mol∙L^‒1 H₂SO₄. More importantly, the catalyst shows prominent high catalytic stability for HER (> 100 h). The acid-resistant MoO_x wraps the inside Ni₃S₂/NF to ensure the high stability of the catalyst under acidic conditions. Density functional theory calculations confirm that the existing oxygen vacancy and MoO_x/Ni₃S₂ heterostructure are both beneficial to the reduced Gibbs free energy of hydrogen adsorption (|∆G_H*|) over Mo sites, which act as main active sites. The heterostructure effectively decreases the formation energy of O vacancy, leading to surface reconstruction of the catalyst, further improving HER performance. The MoO_x/Ni₃S₂/NF is promising to serve as a highly effective and durable electrocatalyst toward HER.

关键词： molybdenum oxides oxygen vacancies heterostructure electrocatalysts hydrogen evolution reaction