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On the added value of multi-scale modeling of concrete

《结构与土木工程前沿（英文）》 2022年第16卷第1期页码 1-23 doi: 10.1007/s11709-021-0790-0

摘要： This review of the added value of multi-scale modeling of concrete is based on three representative examples. The first one is concerned with the analysis of experimental data, taken from four high-dynamic tests. The structural nature of the high-dynamic strength increase can be explained by using a multi-scale model. It accounts for the microstructure of the specimens. The second example refers to multi-scale thermoelastic analysis of concrete pavements, subjected to solar heating. A sensitivity analysis with respect to the internal relative humidity (RH) of concrete has underlined the great importance of the RH for an assessment of the risk of microcracking of concrete. The third example deals with multi-scale structural analysis of a real-scale test of a segmental tunnel ring. It has turned out that multi-scale modeling of concrete enables more reliable predictions of crack opening displacements in tunnel segments than macroscopic models taken from codes of practice. Overall, it is concluded that multi-scale models have indeed a significant added value. However, its degree varies with these examples. In any case, it can be assessed by means of a comparison of the results from three sources, namely, multi-scale structural analysis, conventional structural analysis, and experiments.

关键词： experiments multi-scale analysis conventional structural analysis concrete reinforced concrete

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Techno-economic characteristics of wastewater treatment plants retrofitted from the conventional activated

《环境科学与工程前沿（英文）》 doi: 10.1007/s11783-021-1483-6

摘要：

While a growing number of wastewater treatment plants (WWTPs) are being retrofitted from the conventional activated sludge (CAS) process to the membrane bioreactor (MBR) process, the debate on the techno-economy of MBR vs. CAS has continued and calls for a thorough assessment based on techno-economic valuation.

关键词： Membrane bioreactor (MBR) Conventional activated sludge (CAS) Cost-benefit analysis Data envelopment analysis Net profit

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Energy budget and economic analysis in conventional and organic rice production systems and organic scenarios

Hamed MANSOORI, Parviz Rezvani MOGHADDAM, Rooholla MORADI

《能源前沿（英文）》 2012年第6卷第4期页码 341-350 doi: 10.1007/s11708-012-0206-x

摘要： Compared to conventional agriculture, organic agriculture is reported to be more efficient and effective in reducing water and soil pollution, greenhouse gases (GHGs) emission and risk of human health. In additional, field management under organic condition can be useful for increasing energy efficiency. Rice is one of the important crops which are cultivated in two forms, organic and conventional, in Iran. In order to compare the energy efficiency and economic analysis of rice production in organic and conventional systems in Iran, needed information was collected by face-to-face questionnaire in 2011 and three scenarios were designed to predict the changes of energy budget and economic analysis in the transition period that included: 25%, 50% and 75% organic management in rice production. The results showed that all energy indexes were improved in organic rice production compared to conventional condition. Higher values of benefit to cost ratio, gross and net return and lower value of total cost of production were obtained from organic rice production which indicated that the organic management of farm improved economically in comparison with the conventional rice production system. The shares of direct and renewable energies were increased by approach to organic management. Increase in energy efficiency and productivity was predicted for the transition period but decrease trend in economic indexes was projected for this period in all scenarios. The main reason for decreasing economic indexes in organic scenarios was that the market price of organic rice was the same as that of conventional rice in the transition period.

关键词： energy efficiency specific energy net return Cobb-Douglas function

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Advanced analysis for structural steel building design

CHEN Wai Fah

《结构与土木工程前沿（英文）》 2008年第2卷第3期页码 189-196 doi: 10.1007/s11709-008-0024-8

摘要： The 2005 AISC LRFD Specifications for Structural Steel Buildings are making it possible for designers to recognize explicitly the structural resistance provided within the elastic and inelastic ranges of behavior and up to the maximum load limit state. There is an increasing awareness of the need for practical second-order analysis approaches for a direct determination of overall structural system response. This paper attempts to present a simple, concise and reasonably comprehensive introduction to some of the theoretical and practical approaches which have been used in the traditional and modern processes of design of steel building structures.

关键词： building Specifications comprehensive introduction structural resistance traditional

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Numeric simulation for structure’s damage identification of space truss

JI Weihong, SONG Yupu, LIANG Bing

《机械工程前沿（英文）》 2007年第2卷第4期页码 423-428 doi: 10.1007/s11465-007-0072-0

摘要： Damage detection by using the changes of dynamic parameters is a conventional damage diagnosis method, however, some indices are not sensitive enough to the most structural damages. In this study, the analytical data of displacement modes of truss structure are obtained by using the finite element analysis sof—ANSYS. The mode analysis technique for the axial strain change of any stick is used to detect the steel trusses with different damages. The analytical results show that the damage location and degree of the truss stick can be effectively diagnosed by means of the axial strain change.

关键词： analysis sof—ANSYS conventional displacement element analysis different

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Telomeric impact of conventional chemotherapy

null

《医学前沿（英文）》 2013年第7卷第4期页码 411-417 doi: 10.1007/s11684-013-0293-z

摘要：

The increased level of chromosome instability in cancer cells, leading to aneuploidy and gross chromosomal rearrangements, is not only a driving force for oncogenesis but also can be the Achille’s heel of the disease since many chemotherapies (CT) kill cells by inducing a non-tolerable rate of DNA damage. A wealth of published evidence showed that telomere stability can be more affected than the bulk of the genome by several conventional antineoplasic drugs. These results raise the interesting possibility that CT with genotoxic drugs preferentially target telomeres. In agreement with this view, accelerated shortening of telomere length has been described in blood lineage cells following high-dose CT (stem cell transplantation) or non-myeloablative CT. However, almost nothing is known on the consequences of this shortening in terms of telomere stability, senescence and on the development of second cancers or post-treatment aging-like syndromes in cancer survivors (cognitive defect, fertility impairment, etc.). In this article, we propose: (1) telomeres of cancer cells are preferential genomic targets of chemotherapies altering chromosome maintenance; (2) telomere functional parameters can be a surrogate marker of chemotherapy sensitivity and toxicity; (3) the use of anti-telomere molecule could greatly enhance the sensitivity to standards chemotherapies.

关键词： telomere antineoplasic drugs conventional chemotherapies

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Implementation of an optimum algorithm for structural reliability analysis based on FEM

CHENG Ying, TU Hong-mao, FAN Hong-li

《机械工程前沿（英文）》 2006年第1卷第4期页码 468-471 doi: 10.1007/s11465-006-0061-8

摘要： To analyze structural reliability by the stochastic FE (finite element) method rapidly and efficiently, a method combined with the FE method and gradient optimum algorithm based on ANSYS was presented when referring to the geometric interpretation of structural reliability index. ANSYS-based development was adopted to implement it. Results of an example demonstrate that the method requires fewer FE calculations compared with the design point method and Monte-Carlo simulation, and achieves satisfactory accuracy.

关键词： satisfactory interpretation algorithm structural reliability stochastic FE

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Comprehensive analysis of the influence of structural and dynamic parameters on the accuracy of nano-precision

Chengyuan LIANG, Fang YUAN, Xuedong CHEN, Wei JIANG, Lizhan ZENG, Xin LUO

《机械工程前沿（英文）》 2019年第14卷第3期页码 255-272 doi: 10.1007/s11465-019-0538-x

摘要： Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters, exert a serious influence on the accuracy of its motion and measurement. Systematic evaluation of such influence is essential for the design and improvement of stages. A systematic approach to modeling the dynamic accuracy of a nano-precision positioning stage is developed in this work by integrating a multi-rigid-body dynamic model of the mechanical system and measurement system models. The influence of structural and dynamic parameters, including aerostatic bearing configurations, motion plane errors, foundation vibrations, and positions of the acting points of driving forces, on dynamic accuracy is investigated by adopting the H-type configured stage as an example. The approach is programmed and integrated into a software framework that supports the dynamic design of nano-precision positioning stages. The software framework is then applied to the design of a nano-precision positioning stage used in a packaging lithography machine.

关键词： nano-precision positioning stage analysis and design structural and dynamic parameters dynamic accuracy systematic modeling

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Modeling considerations in seismic assessment of RC bridges using state-of-practice structural analysis

Ricardo MONTEIRO, Miguel ARAÚJO, Raimundo DELGADO, Mário MARQUES

《结构与土木工程前沿（英文）》 2018年第12卷第1期页码 109-124 doi: 10.1007/s11709-017-0389-7

摘要： The increasing awareness of the general society toward the seismic safety of structures has led to more restrictive performance requirements hence, many times, to the need of using new and more accurate methods of analysis of structures. Among these, nonlinear static procedures are becoming, evermore, the preferred choice of the majority of design codes, as an alternative to complete nonlinear time-history analysis for seismic design and assessment of structures. The many available software tools should therefore be evaluated and well understood, in order to be easily and soundly employed by the practitioners. The study presented herein intends to contribute to this need by providing further insight with respect to the use of commonly employed structural analysis software tools in nonlinear analysis of bridge structures. A comparison between different nonlinear modeling assumptions is presented, together with the comparison with real experimental results. Furthermore, alternative adaptive pushover procedures are proposed and applied to a case study bridge, based on a generic plastic hinge model. The adopted structural analysis program proved to be accurate, yielding reliable estimates, both in terms of local plastic hinge behavior and global structural behavior.

关键词： nonlinear analysis pushover RC bridges structural modelling software

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Decomposition analysis applied to energy and emissions: A literature review

《工程管理前沿（英文）》页码 625-639 doi: 10.1007/s42524-023-0270-4

摘要： Decomposition analysis has been widely used to assess the determinants of energy and CO₂ emissions in academic research and policy studies. Both the methodology and application of decomposition analysis have been largely improved in the past decades. After more than 50 years’ developments, decomposition studies have become increasingly sophisticated and diversified, and tend to converge internally and integrate with other analytical approaches externally. A good understanding of the literature and state of the art is critical to identify knowledge gaps and formulate future research agenda. To this end, this study presents a literature survey for decomposition analysis applied to energy and emission issues, with a focus on the period of 2016–2021. A review for three individual decomposition techniques is first conducted, followed by a synthesis of emerging trends and features for the decomposition analysis literature as a whole. The findings are expected to direct future research in decomposition analysis.

关键词： index decomposition analysis structural decomposition analysis production decomposition analysis energy CO₂ emissions

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Proposal of a probabilistic assessment of structural collapse concomitantly subject to earthquake and

Gholamreza ABDOLLAHZADEH, Hadi FAGHIHMALEKI

《结构与土木工程前沿（英文）》 2018年第12卷第3期页码 425-437 doi: 10.1007/s11709-017-0427-5

摘要：

In recent decades, many public buildings, located in seismic-prone residential areas, had to grapple with abnormal loads against which the structures were unguarded. In this piece of research, an ordinary three dimensional reinforced concrete building is selected as case study. The building is located in an earthquake-prone region; however, it is designed according to seismic building codes. Yet, it is not shielded against abnormal loads, such as blasts. It is assumed that the building suffers a blast load, due to mechanical/thermal installation failure during or after intense seismic oscillations. These two critical incidents are regarded codependent and compatible. So the researchers developed scenarios and tried to assess different probabilities for each scenario and carried out an analysis to ensure if progressive collapse had set in or not. In the first step, two analysis models were used for each scenario; a non-linear dynamic time history analysis and a blast local dynamic analysis. In the second step, having the structural destructions of the first step in view, a pushdown analysis was carried out to determine the severity of progressive collapse and assess building robustness. Finally, the annual probability of structural collapse under simultaneous earthquake and blast loads was estimated and offered.

关键词： gas blast pushdown analysis progressive collapse annual probability of structural collapse 3D model of structure

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Shear assessment of compression flanges of structural concrete T-beams

Bj?rn SCHüTTE,Viktor SIGRIST

《结构与土木工程前沿（英文）》 2014年第8卷第4期页码 354-361 doi: 10.1007/s11709-014-0082-z

摘要： In T-beams the force transfer from the web into the flange has to be studied. The general design procedure is based on a strut-and-tie (or a stress field) model which comprises spreading compressive and transverse tensile forces. As is known, strut-and-tie models represent the force flow within a structural member at ultimate. This procedure is sufficient for design purposes and in general, leads to safe results. For the assessment of a structure it may be worthwhile to improve the accuracy. For this purpose both web and flange have to be looked at more in detail. An advanced method for the analysis of webs in shear is the Generalized Stress Field Approach [ ]. This approach can be utilized for treating flanges, where the classical assumptions have to be adapted; in particular by considering the strain dependence of the concrete compressive strength and thus, defining a representative strain value. In the present contribution background and details of these aspects are given, and the corresponding calculation procedure is described. Theoretical results are compared with experimental data and show a reasonably good agreement. However, as the number of sufficiently documented tests is very limited no concluding findings are attained.

关键词： concrete structures structural assessment stress field analysis shear

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Finite element analysis and structural design of pretensioned inverted T-beams with web openings

Hock Tian CHENG, Bashar S. MOHAMMED, Kamal Nasharuddin MUSTAPHA

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 148-157 doi: 10.1007/s11709-009-0030-5

摘要： This paper presents the results of a research project aimed at providing standard circular web openings to the popular precast pretensioned inverted T-beam. Opening size and placement and required materials strengths were investigated. In this paper the nonlinear analysis and design of simply supported pretensioned inverted T-beam with circular web openings are presented. Two design parameters are varied: opening location and number of openings. The results from nonlinear finite element analysis were substantiated by test results from five pretensioned inverted T-beams with web opening and one solid beam. Good agreement is shown between the theoretical and the experimental results. The test results obtained from this investigation show that the performance of the specimens with web openings is almost identical to that of the specimen without web openings. A simple design method for pretensioned inverted T-beam with circular web openings is proposed.

关键词： prestressed concrete inverted-T beam web opening

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Oxygen reduction electrocatalysis: From conventional to single-atomic platinum-based catalysts for proton

《能源前沿（英文）》 doi: 10.1007/s11708-023-0907-3

摘要： Platinum (Pt)-based materials are still the most efficient and practical catalysts to drive the sluggish kinetics of cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, their catalysis and stability performance still need to be further improved in terms of corrosion of both carbon support and Pt catalyst particles as well as Pt loading reduction. Based on the developed synthetic strategies of alloying/nanostructuring Pt particles and modifying/innovating supports in developing conventional Pt-based catalysts, Pt single-atom catalysts (Pt SACs) as the recently burgeoning hot materials with a potential to achieve the maximum utilization of Pt are comprehensively reviewed in this paper. The design thoughts and synthesis of various isolated, alloyed, and nanoparticle-contained Pt SACs are summarized. The single-atomic Pt coordinating with non-metals and alloying with metals as well as the metal-support interactions of Pt single-atoms with carbon/non-carbon supports are emphasized in terms of the ORR activity and stability of the catalysts. To advance further research and development of Pt SACs for viable implementation in PEMFCs, various technical challenges and several potential research directions are outlined.

关键词： oxygen reduction electrocatalysis Pt single-atom catalysts conventional Pt-based catalysts design thoughts and synthesis metal-support interactions