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How does the improved DB mode degrade the complex integrity of infrastructure mega-projects?

Jinwen ZHANG, Yumin QIU

《工程管理前沿（英文）》 2018年 第5卷 第1期   页码 40-51 doi: 10.15302/J-FEM-2018083

摘要： Complex integrity is one of the main characteristics of infrastructure mega-projects (IMPs). Cost, technology, risk, duration, environmental impact, and other uncertain complexities are interrelated and constitute a challenging and complex management problem. At present, there is no unified understanding of or solutions to these complex integrity problems. This study analyzes the complex integrity of the island-tunnel subproject of the Hong Kong-Zhuhai-Macao Bridge (HZMB) project and proposes an improved design-build (DB) mode in which the owner provides a preliminary design and has the right to form and manage consortium. This improved DB mode creatively degrades the special complexities that arise from multiple dimensions. On this basis, it is an efficacious way to grasp the main contradictions, integrate the effective resources, and degrade the complex integrity in multiple dimensions and at multiple levels so as to effectively deal with the complexity management of IMPs.

关键词： Hong Kong-Zhuhai-Macao Bridge project     island-tunnel subproject     complex integrity     complexity degradation     the general contracting mode of design-build     the design-build consortium    

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An Exploration of Surface Integrity Remanufacturing for Aeroengine Components

Qiao Xiang,Yong He,Ting-hong Hou

《工程管理前沿（英文）》 2016年 第3卷 第2期   页码 107-114 doi: 10.15302/J-FEM-2016025

摘要： Surface integrity is the major factor impacting on the operation quality, service life and reliability of the aeroengine components. The surface integrity of aeroengine component is damaged by the failures such as crack, deformation, oxidation, corrosion, erosion, and microstructural degeneration. It adopts advanced remanufacturing technologies to restore or improve the surface integrity and regenerate these high value parts. This paper firstly puts forward the concept, namely surface integrity remanufacturing for aeroengine components, and its connotation. The key remanufacturing technologies have been developed to repair the components with surface damages. Ultimately, some application examples of surface integrity remanufacturing technologies as well as their effects in aeroengine maintenance are introduced. The discarded components have been reused and their service lives have been extended and their reliability has been increased by implementing surface integrity remanufacturing. It has realized “The Repaired Components Outpacing the New Ones”, material saving, energy saving, and emission reduction.

关键词： aeroengine component     surface integrity     remanufacturing     surface integrity remanufacturing    

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Local fracture properties and dissimilar weld integrity in nuclear power plants

Guozhen WANG, Haitao WANG, Fuzhen XUAN, Shantung TU, Changjun LIU

《机械工程前沿（英文）》 2013年 第8卷 第3期   页码 283-290 doi: 10.1007/s11465-013-0250-1

摘要：

In this paper, the local fracture properties in a Alloy52M dissimilar metal welded joint (DMWJ) between A508 ferritic steel and 316 L stainless steel in nuclear power plants were investigated by using the single-edge notched bend (SENB) specimens, and their use in integrity assessment of DMWJ structures was analyzed. The results show that the local fracture resistance in the DMWJ is determined by local fracture mechanism, and which is mainly related to the microstructures and local strength mismatches of materials at the crack locations. The initial cracks always grow towards the materials with lower strength, and the crack path deviation is mainly controlled by the local strength mismatch. If the local fracture properties could not be used for cracks in the heat affected zones (HAZs), interface and near interface zones, the use of the fracture properties ( -resistance curves) of base metals or weld metals following present codes will unavoidably produce non-conservative (unsafe) or excessive conservative assessment results. In most cases, the assessment results will be potentially unsafe. Therefore, it is recommended to obtain and use local mechanical and fracture properties in the integrity assessment of DMWJs.

关键词： local fracture properties     dissimilar metal welded joint     integrity assessment     strength mismatch     crack growth path    

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Emerging challenges to structural integrity technology for high-temperature applications

TU Shantung

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 375-387 doi: 10.1007/s11465-007-0066-y

摘要： Structural integrity technology has been widely used with great success for the design, manufacture and failure prevention of modern constructions such as chemical and petrochemical plants, power generation and energy conversion systems, as well as space and oceanic exploration. The modern needs of structural integrity technology are largely attributed to the increase of service temperature of the structures that results in the efficiency improvement in energy conversion and chemical processing technologies. Besides the needs arising from large-scale high-temperature plants, the high tech developments, such as micro chemo-mechanical systems and high-power electronics, provide new challenges to structural integrity technology. The present paper summarizes the recent technical progresses in large process plants and the aviation industry, micro chemo-mechanical systems, fuel cells, high-temperature electronics, and packaging and coating technologies. The state-of-the-art of structural integrity technology for high temperature applications is reviewed. Suggestions are provided for the improvement of current design and assessment methods.

关键词： manufacture     aviation industry     conversion     petrochemical     temperature    

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Recent development in low-constraint fracture toughness testing for structural integrity assessment of

Jidong KANG, James A. GIANETTO, William R. TYSON

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 546-553 doi: 10.1007/s11465-018-0501-2

摘要：

Fracture toughness measurement is an integral part of structural integrity assessment of pipelines. Traditionally, a single-edge-notched bend (SE(B)) specimen with a deep crack is recommended in many existing pipeline structural integrity assessment procedures. Such a test provides high constraint and therefore conservative fracture toughness results. However, for girth welds in service, defects are usually subjected to primarily tensile loading where the constraint is usually much lower than in the three-point bend case. Moreover, there is increasing use of strain-based design of pipelines that allows applied strains above yield. Low-constraint toughness tests represent more realistic loading conditions for girth weld defects, and the corresponding increased toughness can minimize unnecessary conservatism in assessments. In this review, we present recent developments in low-constraint fracture toughness testing, specifically using single-edge-notched tension specimens, SENT or SE(T). We focus our review on the test procedure development and automation, round-robin test results and some common concerns such as the effect of crack tip, crack size monitoring techniques, and testing at low temperatures. Examples are also given of the integration of fracture toughness data from SE(T) tests into structural integrity assessment.

关键词： fracture toughness     constraint effect     single-edge-notched tension test     pipeline     structural integrity assessment    

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Propagation characteristics of transient waves in low-strain integrity testing on cast-in-situ concrete

Hanlong LIU, Xuanming DING

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 240-240 doi: 10.1007/s11709-009-0100-8

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Experimental study of surface integrity and fatigue life in the face milling of Inconel 718

Xiangyu WANG, Chuanzhen HUANG, Bin ZOU, Guoliang LIU, Hongtao ZHU, Jun WANG

《机械工程前沿（英文）》 2018年 第13卷 第2期   页码 243-250 doi: 10.1007/s11465-018-0479-9

摘要：

The Inconel 718 alloy is widely used in the aerospace and power industries. The machining-induced surface integrity and fatigue life of this material are important factors for consideration due to high reliability and safety requirements. In this work, the milling of Inconel 718 was conducted at different cutting speeds and feed rates. Surface integrity and fatigue life were measured directly. The effects of cutting speed and feed rate on surface integrity and their further influences on fatigue life were analyzed. Within the chosen parameter range, the cutting speed barely affected the surface roughness, whereas the feed rate increased the surface roughness through the ideal residual height. The surface hardness increased as the cutting speed and feed rate increased. Tensile residual stress was observed on the machined surface, which showed improvement with the increasing feed rate. The cutting speed was not an influencing factor on fatigue life, but the feed rate affected fatigue life through the surface roughness. The high surface roughness resulting from the high feed rate could result in a high stress concentration factor and lead to a low fatigue life.

关键词： roughness     hardness     residual stress     microstructure     fatigue life    

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GID complex regulates the differentiation of neural stem cells by destabilizing TET2

《医学前沿（英文）》 doi: 10.1007/s11684-023-1007-9

摘要： Brain development requires a delicate balance between self-renewal and differentiation in neural stem cells (NSC), which rely on the precise regulation of gene expression. Ten-eleven translocation 2 (TET2) modulates gene expression by the hydroxymethylation of 5-methylcytosine in DNA as an important epigenetic factor and participates in the neuronal differentiation. Yet, the regulation of TET2 in the process of neuronal differentiation remains unknown. Here, the protein level of TET2 was reduced by the ubiquitin-proteasome pathway during NSC differentiation, in contrast to mRNA level. We identified that TET2 physically interacts with the core subunits of the glucose-induced degradation-deficient (GID) ubiquitin ligase complex, an evolutionarily conserved ubiquitin ligase complex and is ubiquitinated by itself. The protein levels of GID complex subunits increased reciprocally with TET2 level upon NSC differentiation. The silencing of the core subunits of the GID complex, including WDR26 and ARMC8, attenuated the ubiquitination and degradation of TET2, increased the global 5-hydroxymethylcytosine levels, and promoted the differentiation of the NSC. TET2 level increased in the brain of the Wdr26+/− mice. Our results illustrated that the GID complex negatively regulates TET2 protein stability, further modulates NSC differentiation, and represents a novel regulatory mechanism involved in brain development.

关键词： TET2     GID complex     neural stem cells     differentiation of neurons    

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Footholds optimization for legged robots walking on complex terrain

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0742-y

摘要： This paper proposes a novel continuous footholds optimization method for legged robots to expand their walking ability on complex terrains. The algorithm can efficiently run onboard and online by using terrain perception information to protect the robot against slipping or tripping on the edge of obstacles, and to improve its stability and safety when walking on complex terrain. By relying on the depth camera installed on the robot and obtaining the terrain heightmap, the algorithm converts the discrete grid heightmap into a continuous costmap. Then, it constructs an optimization function combined with the robot’s state information to select the next footholds and generate the motion trajectory to control the robot’s locomotion. Compared with most existing footholds selection algorithms that rely on discrete enumeration search, as far as we know, the proposed algorithm is the first to use a continuous optimization method. We successfully implemented the algorithm on a hexapod robot, and verified its feasibility in a walking experiment on a complex terrain.

关键词： footholds optimization     legged robot     complex terrain adapting     hexapod robot     locomotion control    

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Fiber-reinforced composites in milling and grinding: machining bottlenecks and advanced strategies

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0680-8

摘要： Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.

关键词： milling     grinding     fiber-reinforced composites     damage formation mechanism     delamination     material removal mechanism     surface integrity     minimum quantity lubrication    

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Special issue: Reliability management of complex system

《工程管理前沿（英文）》 2021年 第8卷 第4期   页码 477-479 doi: 10.1007/s42524-021-0175-z

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Independent cover meshless particle method for complex geotechnical engineering

Jianqiu WU, Yongchang CAI

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 515-526 doi: 10.1007/s11709-017-0428-4

摘要： A new Independent Cover Meshless Particle (ICMP) method is proposed for the analysis of complex geotechnical engineering. In the ICMP method, the independent rectangular cover regardless of the shape of the analysis model is employed as the influence domain of each discrete node, the general polynomial is employed as the meshless interpolation function of the independent nodal cover, and the Cartesian Transformation Method (CTM) is used for the numerical integration of the nodal covers cut by material interfaces, joints, cracks and faults. The present method has a simple formulation and a low computational cost, and is easy for the numerical analysis and modeling of complex geotechnical engineering. Several typical numerical examples are presented to demonstrate the accuracy and robustness of the proposed method.

关键词： meshless method     particle method     independent cover     CTM     geotechnical engineering    

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is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice

Yuqin Men, Xiujuan Li, Hailong Tu, Aizhen Zhang, Xiaolong Fu, Zhishuo Wang, Yecheng Jin, Congzhe Hou, Tingting Zhang, Sen Zhang, Yichen Zhou, Boqin Li, Jianfeng Li, Xiaoyang Sun, Haibo Wang, Jiangang Gao

《医学前沿（英文）》 2019年 第13卷 第6期   页码 690-704 doi: 10.1007/s11684-018-0638-8

摘要： encodes the taperin protein, which is concentrated in the tapered region of hair cell stereocilia in the inner ear. In humans, mutations cause autosomal recessive nonsyndromic deafness (DFNB79) by an unknown mechanism. To determine the role of in hearing, we generated -null mice by clustered regularly interspaced short palindromic repeat/Cas9 genome-editing technology from a CBA/CaJ background. We observed significant hearing loss and progressive degeneration of stereocilia in the outer hair cells of -null mice starting from postnatal day 30. Transmission electron microscopy images of stereociliary bundles in the mutant mice showed some stereociliary rootlets with curved shafts. The central cores of the stereociliary rootlets possessed hollow structures with surrounding loose peripheral dense rings. Radixin, a protein expressed at stereocilia tapering, was abnormally dispersed along the stereocilia shafts in null mice. The expression levels of radixin and -actin significantly decreased. We propose that is critical to the retention of the integrity of the stereociliary rootlet. Loss of in -null mice caused the disruption of the stereociliary rootlet, which resulted in damage to stereociliary bundles and hearing impairments. The generated -null mice are ideal models of human hereditary deafness DFNB79.

关键词： TPRN     stereocilia     stereociliary rootlet     actin filament     CRISPR/Cas9     hearing    

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Forecast method for used number of parts and components based on complex network

LIU Fu-yun, QI Guo-ning, YANG Qing-hai

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 479-484 doi: 10.1007/s11465-006-0064-5

摘要： Applying directed complex network to model the main structure of a product family, according to in-degree bi-logarithmic coordinate distribution curve and distribution rule of nodes of the network, in-degree evolving rule of nodes of the network is presented and analytic expression of in-degree probability density of nodes is derived. Through the analysis of the relation between existing kinds of components and existing product numbers, an expression of the relation between kinds of components and product numbers is derived. A forecast method for the increment of component numbers and parts based on the increment of products is presented. As an example, the component numbers of an industrial steam turbine product family is forecasted, forecast result verified and forecast error analyzed.

关键词： complex network     industrial     component     analytic expression     forecast    

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Cationic organobismuth complex as an effective catalyst for conversion of CO

Xiaowen ZHANG, Weili DAI, Shuangfeng YIN, Shenglian LUO, Chak-Tong AU

《环境科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 32-37 doi: 10.1007/s11783-008-0068-y

摘要： In order to achieve high-efficiency conversion of CO into valuable chemicals, and to exploit new applications of organobismuth compounds, cationic organobismuth complex with 5,6,7,12-tetrahydrodibenz[c,f] azabismocine framework was examined for the first time for the coupling of CO into cyclic carbonates, using terminal epoxides as substrates and tetrabutylammonium halide as co-catalyst in a solvent-free environment under mild conditions. It is shown that the catalyst exhibited high activity and selectivity for the coupling reaction of CO with a wide range of terminal epoxide. The selectivity of propylene carbonates could reach 100%, and the maximum turnover frequency was up to 10740 h at 120°C and 3 MPa CO pressure when tetrabutylammonium iodide was used as co-catalyst. Moreover, the catalyst is environment friendly, resistant to air and water, and can be readily reused and recycled without any loss of activity, demonstrating a potential in industrial application.

关键词： cationic organobismuth complex     terminal epoxide     carbon dioxide     coupling     cyclic carbonate    

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标题 作者 时间 类型 操作

How does the improved DB mode degrade the complex integrity of infrastructure mega-projects?

Jinwen ZHANG, Yumin QIU

期刊论文

An Exploration of Surface Integrity Remanufacturing for Aeroengine Components

Qiao Xiang,Yong He,Ting-hong Hou

期刊论文

Local fracture properties and dissimilar weld integrity in nuclear power plants

Guozhen WANG, Haitao WANG, Fuzhen XUAN, Shantung TU, Changjun LIU

期刊论文

Emerging challenges to structural integrity technology for high-temperature applications

TU Shantung

期刊论文

Recent development in low-constraint fracture toughness testing for structural integrity assessment of

Jidong KANG, James A. GIANETTO, William R. TYSON

期刊论文

Propagation characteristics of transient waves in low-strain integrity testing on cast-in-situ concrete

Hanlong LIU, Xuanming DING

期刊论文

Experimental study of surface integrity and fatigue life in the face milling of Inconel 718

Xiangyu WANG, Chuanzhen HUANG, Bin ZOU, Guoliang LIU, Hongtao ZHU, Jun WANG

期刊论文

GID complex regulates the differentiation of neural stem cells by destabilizing TET2

期刊论文

Footholds optimization for legged robots walking on complex terrain

期刊论文

Fiber-reinforced composites in milling and grinding: machining bottlenecks and advanced strategies

期刊论文

Special issue: Reliability management of complex system

期刊论文

Independent cover meshless particle method for complex geotechnical engineering

Jianqiu WU, Yongchang CAI

期刊论文

is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice

Yuqin Men, Xiujuan Li, Hailong Tu, Aizhen Zhang, Xiaolong Fu, Zhishuo Wang, Yecheng Jin, Congzhe Hou, Tingting Zhang, Sen Zhang, Yichen Zhou, Boqin Li, Jianfeng Li, Xiaoyang Sun, Haibo Wang, Jiangang Gao

期刊论文

Forecast method for used number of parts and components based on complex network

LIU Fu-yun, QI Guo-ning, YANG Qing-hai

期刊论文

Cationic organobismuth complex as an effective catalyst for conversion of CO

Xiaowen ZHANG, Weili DAI, Shuangfeng YIN, Shenglian LUO, Chak-Tong AU

期刊论文