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体外预应力 2

三星一线 1

不完备模糊信息系统 1

内外因耦合 1

内模动态 1

凸块锚固区 1

分布式博弈策略；无人机；分布式模型预测控制；基于Levy飞行的鸽群优化算法；非奇异快速终端滑模观测器；避障策略 1

加热、通风和空调 1

化工 1

半导体激光器，光泵浦垂直外腔面发射激光器，纳米激光器，拓扑绝缘体激光器 1

卡尔多–希克斯改进原理 1

发展形势 1

发展战略 1

国家补偿 1

基于依存关系的上下文；多义词表示；表示学习；句法词向量 1

外环 1

外部动态 1

外部性 1

外部短路 1

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Analysis and countermeasures of natural gas development in China

Wenzhi ZHAO, Ailin JIA, Guosheng ZHANG

《工程管理前沿（英文）》 2019年第6卷第4期页码 477-484 doi: 10.1007/s42524-019-0064-x

摘要： Natural gas has become a transitional bridge from fossil to green and clean energy worldwide. The importance of natural gas utilization in energy structure optimization and green development is no exception for China. However, the supply of China’s natural gas limits the country’s demand with three factors. (1) China’s natural gas resource is relatively rich, but its quality is poor with deep burial depth. Therefore, the annual plateau yield of natural gas cannot be high, with an estimated value of approximately 260–270 ×10 m . (2) The demand for natural gas in China’s economic development is growing rapidly. The peak demand is estimated to be approximately 550–650 ×10 m per year or even higher. The import volume of natural gas will soon exceed that of domestic self-produced gas. (3) Natural gas is a necessity closely related to livelihood. Particularly, a shortage in natural gas supply affects social stability. Therefore, its external dependency should be under 50% and not exceed 60%. In this study, the future situation of China’s natural gas is forecasted, and relevant countermeasures and suggestions are proposed in accordance with research on China’s natural gas resource potential, production trend, supply-demand link, and gas supply safety factors.

关键词： natural gas yield consumption external dependency security situation

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Fault evolution-test dependency modeling for mechanical systems

Xiao-dong TAN,Jian-lu LUO,Qing LI,Bing LU,Jing QIU

《信息与电子工程前沿（英文）》 2015年第16卷第10期页码 848-857 doi: 10.1631/FITEE.1500011

摘要： Tracking the process of fault growth in mechanical systems using a range of tests is important to avoid catastrophic failures. So, it is necessary to study the design for testability (DFT). In this paper, to improve the testability performance of mechanical systems for tracking fault growth, a fault evolution-test dependency model (FETDM) is proposed to implement DFT. A testability analysis method that considers fault trackability and predictability is developed to quantify the testability performance of mechanical systems. Results from experiments on a centrifugal pump show that the proposed FETDM and testability analysis method can provide guidance to engineers to improve the testability level of mechanical systems.

关键词： Mechanical systems Design for testability (DFT) Fault evolution-test dependency model (FETDM)

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nitride enabled benzimidazoles production from furyl/aryl bio-alcohols and -nitroanilines without an external

《化学科学与工程前沿（英文）》 2023年第17卷第1期页码 68-81 doi: 10.1007/s11705-022-2174-y

摘要： Benzimidazole derivatives have wide-spectrum biological activities and pharmacological effects, but remain challenging to be produced from biomass feedstocks. Here, we report a green hydrogen transfer strategy for the efficient one-pot production of benzimidazoles from a wide range of bio-alcohols and o-nitroanilines enabled by cobalt nitride species on hierarchically porous and recyclable nitrogen-doped carbon catalysts (Co/CN_x-T, T denotes the pyrolysis temperature) without using an external hydrogen source and base additive. Among the tested catalysts, Co/CN_x-700 exhibited superior catalytic performance, furnishing 2-substituted benzimidazoles in 65%–92% yields. Detailed mechanistic studies manifest that the coordination between Co²⁺ and N with appropriate electronic state on the porous nitrogen-doped carbon having structural defects, as well as the remarkable synergetic effect of Co/N dual sites contribute to the pronounced activity of Co/CN_x-700, while too high pyrolysis temperature may cause the breakage of the catalyst Co–N bond to lower down its activity. Also, it is revealed that the initial dehydrogenation of bio-alcohol and the subsequent cyclodehydrogenation are closely correlated with the hydrogenation of nitro groups. The catalytic hydrogen transfer-coupling protocol opens a new avenue for the synthesis of N-heterocyclic compounds from biomass.

关键词： biomass conversion furanic compounds benzimidazoles hydrogen transfer bifunctional catalysis

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Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain

CHEN Changfu, XIAO Shujun, YANG Yu

《结构与土木工程前沿（英文）》 2007年第1卷第3期页码 329-333 doi: 10.1007/s11709-007-0043-x

摘要： Based on the unified strength theory [1], a unified strength criterion for strain softening materials, such as concrete or rock, was derived, and the elastic and plastic limit loads of a thick-walled cylinder made of these materials subject to external pressure were also given. In addition, the influence of some factors on the limit loads of such cylinders as the ratio of the external radius to internal radius,/, the coefficient , which reflects the effect of medium principal stress and the normal stress of the relevant surface on the material destroy degree, the ratio of tensile strength to compressed strength of the material, , and the damage variable

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monitoring of the strengthening construction of a segmental box girder bridge and field testing of external

Ali Fadhil NASER, Zonglin WANG

《结构与土木工程前沿（英文）》 2012年第6卷第3期页码 308-320 doi: 10.1007/s11709-012-0140-3

摘要： Prestressed concrete segmental box girder bridges are composed of short concrete segments that are either precast or cast in situ and then joined together by longitudinally post-tensioning internal, external, or mixed tendons. The objectives of this study are to monitor the construction process of the external prestressing tendons to strengthen the bridge structure and perform a field load test to measure the strain and the deflection of the anchorage devices of the external prestressing tendons to determine the state of these devices after tension forces are applied. The monitoring process of the external prestressing tendons construction includes inspecting the cracks in the diaphragm anchorage and the deviation block devices before the tension forces are applied to the external tendons; measuring the deformation of the steel deviation cross beam during the tension process; measuring the deformation of the box girder after different levels of tension forces are applied; measuring the elongation of the external tendons in each level of the tension; and measuring the natural frequency of the external tendons after the tension process is complete. The results of the monitoring process show that the measured values of the deformation, the elongation, and the natural frequency meet the requirements. Therefore, there is no damage during the construction and the tensioning of the external prestressing tendons. A field load test is performed to the anchorage beam, the steel deviation block devices, and the steel deviation cross beam. The field load test results of the anchorage devices show that the values of the strains, the stresses, and the deflection are less than the respective allowable limit values in the requirements. Therefore, the anchorage devices have sufficient strength, and the working state is good after the tension forces are applied to the external prestressing tendons.

关键词： prestressed concrete box girder monitoring external tendons strain deflection

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Shear behavior of ultra-high-performance concrete beams prestressed with external carbon fiber-reinforced

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1426-1440 doi: 10.1007/s11709-021-0783-z

摘要： The ultra-high-performance concrete (UHPC) and fiber-reinforced polymer (FRP) are well-accepted high-performance materials in the field of civil engineering. The combination of these advanced materials could contribute to improvement of structural performance and corrosion resistance. Unfortunately, only limited studies are available for shear behavior of UHPC beams reinforced with FRP bars, and few suggestions exist for prediction methods for shear capacity. This paper presents an experimental investigation on the shear behavior of UHPC beams reinforced with glass FRP (GFRP) and prestressed with external carbon FRP (CFRP) tendons. The failure mode of all specimens with various shear span to depth ratios from 1.7 to 4.5 was diagonal tension failure. The shear span to depth ratio had a significant influence on the shear capacity, and the effective prestressing stress affected the crack propagation. The experimental results were then applied to evaluate the equations given in different codes/recommendations for FRP-reinforced concrete structures or UHPC structures. The comparison results indicate that NF P 18-710 and JSCE CES82 could appropriately estimate shear capacity of the slender specimens with a shear span to depth ratio of 4.5. Further, a new shear design equation was proposed to take into account the effect of the shear span to depth ratio and the steel fiber content on shear capacity.

关键词： beam external prestressing ultra-high-performance concrete fiber-reinforced polymers shear behavior design equation

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Ductile extension of 3-D external circumferential cracks in pipe structures

Wuchao YANG, Xudong QIAN

《结构与土木工程前沿（英文）》 2011年第5卷第3期页码 294-303 doi: 10.1007/s11709-011-0115-9

摘要： This study investigates the ductile fracture resistance of 3-D external circumferential cracks in the wall of a steel pipe under remote tension, using a damage-mechanism model originally proposed by Gurson and Tvergaard. The ductile crack extension utilizes an element extinction technique implemented in the computational cell framework. The key parameter for the computational cell method, i.e., the initial porosity ratio , is calibrated using both the fracture resistance and the load-deformation responses obtained from fracture tests of multiple single-edge bend [SE(B)] specimens made of high-strength steel, HY80, which has a yield strength of 630 MPa. The fracture resistance along the 3-D semi-elliptical crack front is computed from the calibrated cell model. Based on the similarity concept in the near-tip stress-strain fields, this study demonstrates that an equivalent 2-D axi-symmetric model provides conservative estimations of the fracture resistance for 3-D circumferential cracks in pipes.

关键词： ductile fracture computational cell method G-T model J-R curve

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Mesh relationship modeling and dynamic characteristic analysis of external spur gears with gear wear

《机械工程前沿（英文）》 2022年第17卷第1期页码 9-9 doi: 10.1007/s11465-021-0665-z

摘要： Gear wear is one of the most common gear failures, which changes the mesh relationship of normal gear. A new mesh relationship caused by gear wear affects meshing excitations, such as mesh stiffness and transmission error, and further increases vibration and noise level. This paper aims to establish the model of mesh relationship and reveal the vibration characteristics of external spur gears with gear wear. A geometric model for a new mesh relationship with gear wear is proposed, which is utilized to evaluate the influence of gear wear on mesh stiffness and unloaded static transmission error (USTE). Based on the mesh stiffness and USTE considering gear wear, a gear dynamic model is established, and the vibration characteristics of gear wear are numerically studied. Comparison with the experimental results verifies the proposed dynamic model based on the new mesh relationship. The numerical and experimental results indicate that gear wear does not change the structure of the spectrum, but it alters the amplitude of the meshing frequencies and their sidebands. Several condition indicators, such as root-mean-square, kurtosis, and first-order meshing frequency amplitude, can be regarded as important bases for judging gear wear state.

关键词： gear wear mesh relationship mesh stiffness transmission error vibration characteristics

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单向离合器外环应力计算的有限元方法研究

罗一新,吴波

《中国工程科学》 2004年第6卷第9期页码 56-59

摘要：

单向离合器是一种常见的机械传动部件，其外环应力计算尚无理想的方法。文章以五滚柱式单向离合器为研究对象，根据外环的特点，采用有限元分析方法，分析了影响其计算精度的各种因素，计算出其外环的应力，并且将计算结果与曲梁计算法进行了比较。研究表明，有限元分析方法对于外环类零件的应力计算确是一种理想的方法。

关键词：离合器外环应力有限元

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patients with advanced malignant obstructive jaundice treated by percutaneous transhepatic biliary external

ZHU Lidong, CHEN Xiaoping

《医学前沿（英文）》 2007年第1卷第4期页码 364-368 doi: 10.1007/s11684-007-0070-y

摘要： The aim of this article was to study the influence of immunity function of advanced malignant obstructive jaundice (MOJ) treated by percutaneous transhepatic biliary external and internal drainage. Ninety-six cases of MOJ were divided into two groups according to the different ways of biliary drainage. Fifty-two external drainage tubes were placed in 41 cases of percutaneous transhepatic biliary external drainage group and 66 metal stents were placed in 55 cases of percutaneous transhepatic biliary internal drainage group. Liver function, serum TNF- and cellular function were examined one day before operation and one week after operation and liver function was re-examined two weeks after operation, in order to observe the change and analyze the asso ciation among them and compare with the control group. All patients conditions were improved after operation. In the percutaneous transhepatic biliary external and internal drainage groups, the total level of bilirubin decreased from (343.54±105.56) μ mol/L and (321.19±110.50) μ mol/L to (290.56±103.46) μ mol/L and (283.72±104.95) μ mol/L after operation respectively, which were significantly lower than pre-operation (<0.05), but there was no significant difference between the two groups (>0.05). Serum alanine aminotransferase (ALT) of all patients one week after operation was significantly lower than that before operation. TNF- in percutaneous transhepatic biliary external and internal groups decreased from (108.58±19.95) pg/mL, (109.98±16.24) pg/mL of pre-operation to (104.32±19.59) pg/mL, (83.92±13.43) pg/mL of post-operation respectively, there was notable improvement (<0.01) in internal drainage group after operation. Patients serum CD4, CD3 and CD4/CD8 were notably increased, but CD8 was notably decreased (<0.05). There was no difference in external drainage group (>0.05). There was a significant difference between the two groups. Serum TNF- and ALT had positive correlation. Percutaneous transhepatic biliary internal or external drainage was an effective and important method to treat MOJ. Patients immune function was weak when they suffered MOJ, but body s cellular immune function can be notably improved after internal biliary drainage.

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基于依存关系和多义词分析的句法词嵌入 None

Zhong-lin YE, Hai-xing ZHAO

《信息与电子工程前沿（英文）》 2018年第19卷第4期页码 524-535 doi: 10.1631/FITEE.1601846

摘要：现有大多数词嵌入学习模型存在以下问题：（1）基于词袋上下文的模型完全忽略句子的句法结构关系；（2）每个词使用单个嵌入向量使多义词共享一个嵌入向量；（3）词嵌入往往趋向于句子上下文共性。为解决这些问题，提出一种基于依存关系和多义词分析的句法词嵌入（syntactic word embedding, SWE）。该算法主要处理：（1）基于主题模型，提出一个多义词识别算法；（2）采用符号“+”和“−”表示依存关系方向；（3）删除停用词及其依存关系；（4）引入“skip”依存关系表示依存关系之间的间接关系；（5）将基于依存关系的上下文输入到Word2Vec模型中训练语言模型。实验结果表明，SWE模型在词相似度评测任务中表现出优异性能。基于依存关系句法上下文捕获词语的语义和句法特征，使词语表现出较少的上下文主题相似性和更多的句法和语义相似性。综上，包含更多信息的SWE模型性能优于单一的词嵌入学习模型。

关键词：基于依存关系的上下文；多义词表示；表示学习；句法词向量

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Axisymmetric loading on nanoscale multilayered media

《结构与土木工程前沿（英文）》 2023年第17卷第1期页码 152-164 doi: 10.1007/s11709-022-0895-0

摘要： Multilayered nanoscale structures are used in several applications. Because the effect of surface energy becomes nontrivial at such a small scale, a modified continuum theory is required to accurately predict their mechanical behaviors. A Gurtin–Murdoch continuum model of surface elasticity is implemented to establish a computational scheme for investigating an elastic multilayered system under axisymmetric loads with the incorporation of surface/interface energy. Each layer stiffness matrix is derived based on the general solutions of stresses and displacements obtained in the form of the Hankel integral transform. Numerical solutions to the global equation, which are formulated based on the continuity conditions of tractions and displacements across interfaces between layers, yield the displacements at each layer interface and on the top surface of the multilayered medium. The numerical solutions indicate that the elastic responses of multilayered structures are affected significantly by the surface material properties of both the top surface and interfaces, and that they become size dependent. In addition, the indentation problem of a multilayered nanoscale elastic medium under a rigid frictionless cylindrical punch is investigated to demonstrate the application of the proposed solution scheme.

关键词： functionally graded layer Gurtin–Murdoch surface elasticity multilayered medium size dependency stiffness matrix

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Intrinsic kinetics and external diffusion of catalytic steam gasification of fine coal char particles

Xuantao Wu, Jie Wang

《化学科学与工程前沿（英文）》 2019年第13卷第2期页码 415-426 doi: 10.1007/s11705-018-1725-8

摘要： Catalytic steam gasification of fine coal char particles was carried out using a self-made laboratory reactor to determine the intrinsic kinetics and external diffusion under varying pressures (0.1–0.5 MPa) and superficial gas flow velocities (GFVs) of 13.8–68.8 cm?s . In order to estimate the gas release rate at a low GFV, the transported effect of effluent gas on the temporal gasification rate pattern was simulated by the Fluent computation and verified experimentally. The external mass transfer coefficients ( ) and the effectiveness factors were determined at lower GFVs, based on the intrinsic gasification rate obtained at a high GFV of 55.0 cm?s . The was found to be almost invariable in a wider carbon conversion of 0.2–0.7. The variations of at a median carbon conversion with GFV, temperature and pressure were found to follow a modified Chilton-Colburn correlation: (0.04< <0.19), where is total pressure and is atmospheric pressure. An intrinsic kinetics/external diffusion integrating model could well describe the gasification rate as a function of GFV, temperature and pressure over a whole gasification process.

关键词： coal char catalytic steam gasification pressure kinetics diffusion

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体内-体外混合配束节段预制拼装箱梁足尺模型试验研究

郑开启,卜红旗,刘钊,惠卓,吕志涛

《中国工程科学》 2013年第15卷第8期页码 89-94

摘要：

以南京长江第四大桥引桥为背景，开展了一孔48 m跨径体内-体外混合配束节段预制拼装箱梁的足尺模型试验，以研究该类箱梁在正常使用阶段和施工状态下的结构行为。根据试验箱梁的尺寸参数以及实际约束条件确定了拼装与加载方案。本文重点研究正常使用荷载和梁上运梁两种工况下梁体应力状况与位移变化等结构静力性能，并与试验梁实体有限元模型进行对比分析。研究结果表明：在正常使用阶段，加、卸载后拼装梁体残余变形较小，基本处于弹性工作状态，整体性较好；键齿接缝两侧基本无相对滑移，接缝截面纵向应变沿梁高大致呈线性变化，力学行为基本符合平截面假定；体外预应力束在转向处基本无滑移，体内外预应力增量随跨中弯矩基本呈线性变化；在梁上运梁工况下，实测梁体下缘压应力储备充足，满足运梁安全性要求。

关键词：节段预制拼装模型试验体外预应力足尺试验