资源类型

期刊论文 169

会议视频 6

年份

2023 21

2022 13

2021 12

2020 10

2019 13

2018 9

2017 10

2016 8

2015 5

2014 2

2013 9

2012 5

2011 9

2010 3

2009 7

2008 8

2007 5

2006 3

2005 2

2004 6

展开 ︾

关键词

钢结构 4

人脸识别 2

优化设计 2

增材制造 2

机械结构 2

混凝土面板堆石坝 2

特征抽取 2

独头巷道 2

疲劳寿命 2

3D打印 1

3D生物打印 1

CFD 1

Cascaded 型检测器 1

DNA结构 1

EBL 1

FIB 1

ICP 1

LASC 1

Mallat算法 1

展开 ︾

检索范围：

排序： 展示方式：

Formic acid dehydrogenation reaction on high-performance PdAu alloy nanoparticles prepared by the eco-friendly slow synthesis methodology

《能源前沿（英文）》   页码 751-762 doi: 10.1007/s11708-023-0895-3

摘要： Dehydrogenation of formic acid (FA) is considered to be an effective solution for efficient storage and transport of hydrogen. For decades, highly effective catalysts for this purpose have been widely investigated, but numerous challenges remain. Herein, the PdxAu1−x (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloys over the whole composition range were successfully prepared and used to catalyze FA hydrogen production efficiently near room temperature. Small PdAu nanoparticles (5–10 nm) were well-dispersed and supported on the activated carbon to form PdAu solid solution alloys via the eco-friendly slow synthesis methodology. The physicochemical properties of the PdAu alloys were comprehensively studied by utilizing various measurement methods, such as X-ray diffraction (XRD), N2 adsorption–desorption, high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), X-ray photoelectrons spectroscopy (XPS). Notably, owing to the strong metal-support interaction (SMSI) and electron transfer between active metal Au and Pd, the Pd0.5Au0.5 obtained exhibits a turnover frequency (TOF) value of up to 1648 h−1 (313 K, nPd+Au/nFA = 0.01, nHCOOH/nHCOONa = 1:3) with a high activity, selectivity, and reusability in the FA dehydrogenation.

关键词： FA dehydrogenation     face-centred cubic structures     PdAu solid solution alloy nanoparticles     slow synthesis methodology     SMSI effect    

HTML PDF 收藏

Novel decoupled framework for reliability-based design optimization of structures using a robust shifting

Mohammad Reza GHASEMI, Charles V. CAMP, Babak DIZANGIAN

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 800-820 doi: 10.1007/s11709-019-0517-7

摘要： In a reliability-based design optimization (RBDO), computation of the failure probability ( ) at all design points through the process may suitably be avoided at the early stages. Thus, to reduce extensive computations of RBDO, one could decouple the optimization and reliability analysis. The present work proposes a new methodology for such a decoupled approach that separates optimization and reliability analysis into two procedures which significantly improve the computational efficiency of the RBDO. This technique is based on the probabilistic sensitivity approach (PSA) on the shifted probability density function. Stochastic variables are separated into two groups of desired and non-desired variables. The three-phase procedure may be summarized as: Phase 1, apply deterministic design optimization based on mean values of random variables; Phase 2, move designs toward a reliable space using PSA and finding a primary reliable optimum point; Phase 3, applying an intelligent self-adaptive procedure based on cubic B-spline interpolation functions until the targeted failure probability is reached. An improved response surface method is used for computation of failure probability. The proposed RBDO approach could significantly reduce the number of analyses required to less than 10% of conventional methods. The computational efficacy of this approach is demonstrated by solving four benchmark truss design problems published in the structural optimization literature.

关键词： reliability-based design optimization     trusses     sensitivity analysis     shifting technique     cubic B-splines     response surface method    

HTML PDF 收藏

Evaluation method of multiaxial low cycle fatigue life for cubic single crystal material

CHEN Jiping, DING Zhiping

《机械工程前沿（英文）》 2007年 第2卷 第3期   页码 278-282 doi: 10.1007/s11465-007-0048-0

摘要： The coupling effect of normal stress and shear stress on orthotropic materials happens when applied loading deflects from the directions of the principal axes of the material coordinate system. By taking account of the coupling effects, formulas of equivalent stress and strain for cubic single crystal materials are cited. Using the equivalent strain and equivalent stress for such material and a variable k, which is introduced to express the effect of asymmetrical cyclic loading on fatigue life, a low cycle fatigue (LCF) life prediction model for such material in multiaxial stress starts is proposed. On the basis of the yield criterion and constitutive model of cubic single crystal materials, a subroutine to calculate the thermo elastic-plastic stress-strain of the material on an ANSYS platform was developed. The cyclic stress-strain of DD3 notched specimens under asymmetrical loading at 680vH was analyzed. Low cycle fatigue test data of the single crystal nickel-based superalloy are used to fit the different parameters of the power law with multiple linear regression analysis. The equivalent stress and strain for a cubic single crystal material as failure parameters have the largest correlation coefficient. A power law exists between k and the failure cycle. The model was validated with LCF test data of CMSX-2 and DD3 single crystal nickel-based superalloys. All the test data fall into the factor of 2.5 for CMSX-2 hollow cylinder specimens and 2.0 scatter band for DD3 notched specimens, respectively.

关键词： orthotropic     regression analysis     crystal material     multiaxial     prediction    

HTML PDF 收藏

Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

YUE Hongxia, ZHAO Hongmei, LIU Longjiang, WANG Siping, Ruan Qiong, WANG Tongwen

《化学科学与工程前沿（英文）》 2008年 第2卷 第2期   页码 135-139 doi: 10.1007/s11705-008-0031-2

摘要： The long-chain ionic liquid 1-hexadecyl-3-methylimidazolium chloride (CmimCl) was used as a template to prepare cerium-doped MCM-48 materials in basic medium by a hydrothermal synthesis procedure. The effect of the amount of Ce salt and CmimCl/Si on the synthesis were discussed in detail. This mesoporous material exhibits a pore architecture which is cubic 3 gyroid and possesses a large surface area and a narrow pore distribution. Cerium in calcined porous framework exists in the form of well-dispersed tetrahedral coordination. The CmimCl shows a high tendency toward self-aggregation that allows the formation of the cerium-doped gyroid mesostructure by using the appropriate amount of Ce salt.

关键词： mesoporous     CmimCl/Si     tendency     mesostructure     synthesis procedure    

HTML PDF 收藏

Crystal-to-crystal transformation from the triclinic to the cubic crystal system by partial desolvation

Qianqian Guo, Irmgard Kalf, Ulli Englert

《化学科学与工程前沿（英文）》 2018年 第12卷 第3期   页码 433-439 doi: 10.1007/s11705-018-1743-6

摘要：

Diffusion reaction of the labile building block Mg(acacCN)2 (acacCN= 3-cyanoacetylacetonate) with silver salts leads to a series of solvated Mg/Ag bimetallic coordination polymers with composition [Mg(acacCN)3Ag]·solvent. Despite their common stoichiometry, the topology of these polymers depends on the solvent of crystallization. The two-dimensional coordination compound [Mg(acacCN)3Ag]·4CHCl3 in space group P1‾ is obtained as platelet-shaped crystals from a mixture of methanol and chloroform. When kept in the reaction mixture, these thin plates within one week convert to isometric tetrahedral crystals of the 3D network [Mg(acacCN)3Ag]·2CHCl3 in the cubic space group P213. The transformation reaction proceeds via dissolution and recrystallization. The co-crystallized solvent molecules play an important role for stabilizing the target structure: They subtend Cl···Cl contacts and interact via non-classical C–H···O hydrogen bonds with the coordination framework. In the new cubic coordination network, both Mg(II) and Ag(I) adopt octahedral coordination, with unprecedented face-sharing by bridging O atoms of three acetylacetonato moieties. Prolonged standing of [Mg(acacCN)3Ag]·2CHCl3 in the reaction medium leads to further degradation, under formation of [Ag(acacCN)].

关键词： ditopic ligand     substituted acetylacetone     desolvation     diffraction    

HTML PDF 收藏

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 522-532 doi: 10.1007/s11709-023-0930-9

摘要： Owing to long-distance advancement or obstacles, shield tunneling machines are typically shut down for maintenance. Engineering safety during maintenance outages is determined by the stability of the tunnel face. Pressure maintenance openings are typically used under complicated hydrogeological conditions. The tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the top. Owing to the high risk of face failure, the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be determined. In this study, a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit analysis. Numerical simulation is conducted to verify the accuracy of the proposed model. The results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of collapse. The required compressed air pressure increases significantly as the support ratio decreases. Disregarding the supporting effect of the cutterhead will result in a tunnel face with underestimated stability. To satisfy the requirement of chamber openings at atmospheric pressure, the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词： tunnel face stability     cutterhead configuration     aperture ratio     pressure gradient     support ratio    

HTML PDF 收藏

Synthesis and electrocatalytic property of cubic and spherical nanoparticles of cobalt platinum alloys

Xiaowei TENG, Hong YANG,

《化学科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 45-51 doi: 10.1007/s11705-009-0308-0

摘要： This paper describes the morphological control and electrocatalytic property of CoPt nanoparticles. Both cubic and spherical CoPt nanoparticles were made using cobalt carbonyl and platinum 2,4-pentanedionate under different reaction temperatures in the presence of capping reagents, which included adamantanecarboxylic acid and hexadecylamine. Effects of heterogeneous species on shape of the CoPt nanoparticles were examined by replacing cobalt carbonyl with silver acetylacetonate. Our results suggest that the formation of different shapes of CoPt particles could be attributed to the affinity between cobalt and platinum, and the effects of capping agents. The size and shape dependent electrocatalytic properties of these nanoparticles were examined based on the direct methanol oxidation reaction.

关键词： spherical     2     4-pentanedionate     adamantanecarboxylic     acetylacetonate     electrocatalytic    

HTML PDF 收藏

Method for solving the nonlinear inverse problem in gas face seal diagnosis based on surrogate models

《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0689-z

摘要： Physical models carry quantitative and explainable expert knowledge. However, they have not been introduced into gas face seal diagnosis tasks because of the unacceptable computational cost of inferring the input fault parameters for the observed output or solving the inverse problem of the physical model. The presented work develops a surrogate-model-assisted method for solving the nonlinear inverse problem in limited physical model evaluations. The method prepares a small initial database on sites generated with a Latin hypercube design and then performs an iterative routine that benefits from the rapidity of the surrogate models and the reliability of the physical model. The method is validated on simulated and experimental cases. Results demonstrate that the method can effectively identify the parameters that induce the abnormal signal output with limited physical model evaluations. The presented work provides a quantitative, explainable, and feasible approach for identifying the cause of gas face seal contact. It is also applicable to mechanical devices that face similar difficulties.

关键词： surrogate model     gas face seal     fault diagnosis     nonlinear dynamics     tribology    

HTML PDF 收藏

Strengthening of the concrete face slabs of dams using sprayable strain-hardening fiber-reinforced cementitious

《结构与土木工程前沿（英文）》 2022年 第16卷 第2期   页码 145-160 doi: 10.1007/s11709-022-0806-4

摘要： In this study, sprayable strain-hardening fiber-reinforced cementitious composites (FRCC) were applied to strengthen the concrete slabs in a concrete-face rockfill dam (CFRD) for the first time. Experimental, numerical, and analytical investigations were carried out to understand the flexural properties of FRCC-layered concrete slabs. It was found that the FRCC layer improved the flexural performance of concrete slabs significantly. The cracking and ultimate loads of a concrete slab with an 80 mm FRCC layer were 132% and 69% higher than those of the unstrengthened concrete slab, respectively. At the maximum crack width of 0.2 mm, the deflection of the 80-mm FRCC strengthened concrete slab was 144% higher than that of the unstrengthened concrete slab. In addition, a FE model and a simplified analytical method were developed for the design and analysis of FRCC-layered concrete slabs. Finally, the test result of FRCC leaching solution indicated that the quality of the water surrounding FRCC satisfied the standard for drinking water. The findings of this study indicate that the sprayable strain-hardening FRCC has a good potential for strengthening hydraulic structures such as CFRDs.

关键词： strain-hardening cementitious composites     engineered cementitious composites     sprayable     shotcrete     strengthening     concrete-face rockfill dam     digital image correlation    

HTML PDF 收藏

Dynamic in-plane transversal normal stresses in the concrete face of CFRD

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 135-148 doi: 10.1007/s11709-018-0481-7

摘要： Severe earthquakes can induce damages to Concrete Face Rockfill Dams (CFRDs) such as concrete cracking and joint's water stops distressing where high in-plane transversal normal stresses develop. Although these damages rarely jeopardize the dam safety, they cause large water reservoir leakages that hinder the dam functioning. This issue can be addressed using well know numerical methods; however, given the wide range of parameters involved, it would seem appropriate to develop a simple yet reliable procedure to get a close understanding how their interaction affects the CFRD’s overall behavior. Accordingly, once the physics of the problem is better understood one can proceed to perform a detailed design of the various components of the dam. To this end an easy-to-use procedure that accounts for the dam height effects, valley narrowness, valley slopes, width of concrete slabs and seismic excitation characteristics was developed. The procedure is the dynamic complement of a method recently developed to evaluate in-plane transversal normal stresses in the concrete face of CFRD’s due to dam reservoir filling [ ]. Using these two procedures in a sequential manner, it is possible to define the concrete slab in-plane normal stresses induced by the reservoir filling and the action of orthogonal horizontal seismic excitations acting at the same time upstream-downstream and cross river. Both procedures were developed from a data base generated using nonlinear static and dynamic three-dimensional numerical analyses on the same group of CFRD’s. Then, the results were interpreted with the Buckingham Pi theorem and various relationships were developed. In the above reference, the method to evaluate the concrete face in-plane transversal normal stresses caused by the first reservoir filling was reported. In this paper, the seismic procedure is first developed and then through an example the whole method (dam construction, reservoir filling plus seismic loading) of analysis is assessed.

关键词： CFR dams     dynamic analysis     in-plane normal stresses     concrete face    

HTML PDF 收藏

Local uncorrelated local discriminant embedding for face recognition

Xiao-hu MA,Meng YANG,Zhao ZHANG

《信息与电子工程前沿（英文）》 2016年 第17卷 第3期   页码 212-223 doi: 10.1631/FITEE.1500255

摘要： The feature extraction algorithm plays an important role in face recognition. However, the extracted features also have overlapping discriminant information. A property of the statistical uncorrelated criterion is that it eliminates the redundancy among the extracted discriminant features, while many algorithms generally ignore this property. In this paper, we introduce a novel feature extraction method called local uncorrelated local discriminant embedding (LULDE). The proposed approach can be seen as an extension of a local discriminant embedding (LDE) framework in three ways. First, a new local statistical uncorrelated criterion is proposed, which effectively captures the local information of interclass and intraclass. Second, we reconstruct the affinity matrices of an intrinsic graph and a penalty graph, which are mentioned in LDE to enhance the discriminant property. Finally, it overcomes the small-sample-size problem without using principal component analysis to preprocess the original data, which avoids losing some discriminant information. Experimental results on Yale, ORL, Extended Yale B, and FERET databases demonstrate that LULDE outperforms LDE and other representative uncorrelated feature extraction methods.

关键词： Feature extraction     Local discriminant embedding     Local uncorrelated criterion     Face recognition    

HTML PDF 收藏

In-plane transversal normal stresses in the concrete face of CFRD induced by the first-dam reservoir

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 81-91 doi: 10.1007/s11709-016-0378-2

摘要： To evaluate the effects of dam height, valley narrowness and width of concrete slabs on the first-dam reservoir filling in-plane transversal normal stresses in the concrete face of CFRD´s, 3D finite difference analyses were carried out. Behavior of rockfill dams considered in this study was defined from the monitoring of a number of 3D sets of pressure cells and extensometers installed in three large dams in Mexico. The 3D analyses results show that high in-plane transversal compressive stresses develop within the concrete panels located in the central concrete face zone upon dam reservoir filling loading. Likewise, in-plane induced tensile transversal stresses in the zones near the abutments increase the potential of slabs cracking and damaging the waterstops in-between the vertical and perimetral joints. From the results of the 3D finite difference analyses, a simple method to estimate in-plane normal stresses in the concrete face is advanced and through comparisons with the results of a 3D case numerical study, its accuracy assessed.

关键词： concrete face     CFR dams     reservoir filling     slab in-plane stresses    

HTML PDF 收藏

Model test and discrete element method simulation of shield tunneling face stability in transparent clay

Huayang LEI, Yajie ZHANG, Yao HU, Yingnan LIU

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 147-166 doi: 10.1007/s11709-020-0704-6

摘要： The stability of the shield tunneling face is an extremely important factor affecting the safety of tunnel construction. In this study, a transparent clay with properties similar to those of Tianjin clay is prepared and a new transparent clay model test apparatus is developed to overcome the “black box” problem in the traditional model test. The stability of the shield tunneling face (failure mode, influence range, support force, and surface settlement) is investigated in transparent clay under active failure. A series of transparent clay model tests is performed to investigate the active failure mode, influence range, and support force of the shield tunneling face under different burial depth conditions, whereas particle flow code three-dimensional numerical simulations are conducted to verify the failure mode of the shield tunneling face and surface settlement along the transverse section under different burial depth conditions. The results show that the engineering characteristics of transparent clay are similar to those of soft clay in Binhai, Tianjin and satisfy visibility requirements. Two types of failure modes are obtained: the overall failure mode (cover/diameter: / ≤1.0) and local failure mode ( / ≥2.0). The influence range of the transverse section is wider than that of the longitudinal section when / ≥2.0. Additionally, the normalized thresholds of the relative displacement and support force ratio are 3%–6% and 0.2–0.4, respectively. Owing to the cushioning effect of the clay layer, the surface settlement is significantly reduced as the tunnel burial depth increases.

关键词： shield tunneling face     stability     transparent clay     model test     numerical simulation    

HTML PDF 收藏

Investigation of Generalized SIFs of cracks in 3D piezoelectric media under various crack-face conditions

Jaroon RUNGAMORNRAT, Bounsana CHANSAVANG, Weeraporn PHONGTINNABOOT, Chung Nguyen VAN

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 280-298 doi: 10.1007/s11709-019-0586-7

摘要： This paper investigates the influence of crack geometry, crack-face and loading conditions, and the permittivity of a medium inside the crack gap on intensity factors of planar and non-planar cracks in linear piezoelectric media. A weakly singular boundary integral equation method together with the near-front approximation is adopted to accurately determine the intensity factors. Obtained results indicate that the non-flat crack surface, the electric field, and the permittivity of a medium inside the crack gap play a crucial role on the behavior of intensity factors. The mode-I stress intensity factors ( ) for two representative non-planar cracks under different crack-face conditions are found significantly different and they possess both upper and lower bounds. In addition, for impermeable and semi-permeable non-planar cracks treated depends strongly on the electric field whereas those of impermeable, permeable, and semi-permeable penny-shaped cracks are identical and independent of the electric field. The stress/electric intensity factors predicted by permeable and energetically consistent models are, respectively, independent of and dependent on the electric field for the penny-shaped crack and the two representative non-planar cracks. Also, the permittivity of a medium inside the crack gap strongly affects the intensity factors for all crack configurations considered except for of the semi-permeable penny-shaped crack.

关键词： crack-face conditions     intensity factors     non-flat cracks     permittivity     piezoelectric media     SGBEM    

HTML PDF 收藏

Multiobjective trajectory optimization of intelligent electro-hydraulic shovel

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0706-2

摘要： Multiobjective trajectory planning is still face challenges due to certain practical requirements and multiple contradicting objectives optimized simultaneously. In this paper, a multiobjective trajectory optimization approach that sets energy consumption, execution time, and excavation volume as the objective functions is presented for the electro-hydraulic shovel (EHS). The proposed cubic polynomial S-curve is employed to plan the crowd and hoist speed of EHS. Then, a novel hybrid constrained multiobjective evolutionary algorithm based on decomposition is proposed to deal with this constrained multiobjective optimization problem. The normalization of objectives is introduced to minimize the unfavorable effect of orders of magnitude. A novel hybrid constraint handling approach based on -constraint and the adaptive penalty function method is utilized to discover infeasible solution information and improve population diversity. Finally, the entropy weight technique for order preference by similarity to an ideal solution method is used to select the most satisfied solution from the Pareto optimal set. The performance of the proposed strategy is validated and analyzed by a series of simulation and experimental studies. Results show that the proposed approach can provide the high-quality Pareto optimal solutions and outperforms other trajectory optimization schemes investigated in this article.

关键词： trajectory planning     electro-hydraulic shovel     cubic polynomial S-curve     multiobjective optimization     entropy weight technique    

HTML PDF 收藏

标题 作者 时间 类型 操作

Formic acid dehydrogenation reaction on high-performance PdAu alloy nanoparticles prepared by the eco-friendly slow synthesis methodology

期刊论文

Novel decoupled framework for reliability-based design optimization of structures using a robust shifting

Mohammad Reza GHASEMI, Charles V. CAMP, Babak DIZANGIAN

期刊论文

Evaluation method of multiaxial low cycle fatigue life for cubic single crystal material

CHEN Jiping, DING Zhiping

期刊论文

Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

YUE Hongxia, ZHAO Hongmei, LIU Longjiang, WANG Siping, Ruan Qiong, WANG Tongwen

期刊论文

Crystal-to-crystal transformation from the triclinic to the cubic crystal system by partial desolvation

Qianqian Guo, Irmgard Kalf, Ulli Englert

期刊论文

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

期刊论文

Synthesis and electrocatalytic property of cubic and spherical nanoparticles of cobalt platinum alloys

Xiaowei TENG, Hong YANG,

期刊论文

Method for solving the nonlinear inverse problem in gas face seal diagnosis based on surrogate models

期刊论文

Strengthening of the concrete face slabs of dams using sprayable strain-hardening fiber-reinforced cementitious

期刊论文

Dynamic in-plane transversal normal stresses in the concrete face of CFRD

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

期刊论文

Local uncorrelated local discriminant embedding for face recognition

Xiao-hu MA,Meng YANG,Zhao ZHANG

期刊论文

In-plane transversal normal stresses in the concrete face of CFRD induced by the first-dam reservoir

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

期刊论文

Model test and discrete element method simulation of shield tunneling face stability in transparent clay

Huayang LEI, Yajie ZHANG, Yao HU, Yingnan LIU

期刊论文

Investigation of Generalized SIFs of cracks in 3D piezoelectric media under various crack-face conditions

Jaroon RUNGAMORNRAT, Bounsana CHANSAVANG, Weeraporn PHONGTINNABOOT, Chung Nguyen VAN

期刊论文

Multiobjective trajectory optimization of intelligent electro-hydraulic shovel

期刊论文