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Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

《结构与土木工程前沿(英文)》 2017年 第11卷 第4期   页码 412-423 doi: 10.1007/s11709-017-0416-8

摘要: Construction loading before the age of 28 d can have the most significant effects on the slabs, especially for multi-story structures. The changing properties of the young concrete complicate the prediction of serviceability design requirements also. An experimental investigation is performed on four simply supported Light-Weight Concrete (LWC) one-way slabs subjected to immediate loading at 14 d. Effects of aggregate type, loading levels and cracking moment together with the influences of ultimate moment capacity and service moment on the instantaneous deflection of slabs are studied. Comparison of the obtained results with predictions of existing models in the literature shows considerable differences between the recorded and estimated instantaneous deflection of LWC slabs. Based on sensitivity analysis of the effective parameters, a new equation is proposed and verified to predict the instantaneous deflection of LWC slabs subjected to loading at the age of 14 d.

关键词: instantaneous deflection     light-weight concrete     expanded polystyrene     effective moment of inertia     cracking moment     moment capacity     service moment    

Materials-oriented integrated design and construction of structures in civil engineering—A review

《结构与土木工程前沿(英文)》 2022年 第16卷 第1期   页码 24-44 doi: 10.1007/s11709-021-0794-9

摘要: Design is a goal-oriented planning activity for creating products, processes, and systems with desired functions through specifications. It is a decision-making exploration: the design outcome may vary greatly depending on the designer’s knowledge and philosophy. Integrated design is one type of design philosophy that takes an interdisciplinary and holistic approach. In civil engineering, structural design is such an activity for creating buildings and infrastructures. Recently, structural design in many countries has emphasized a performance-based philosophy that simultaneously considers a structure’s safety, durability, serviceability, and sustainability. Consequently, integrated design in civil engineering has become more popular, useful, and important. Material-oriented integrated design and construction of structures (MIDCS) combine materials engineering and structural engineering in the design stage: it fully utilizes the strengths of materials by selecting the most suitable structural forms and construction methodologies. This paper will explore real-world examples of MIDCS, including the realization of MIDCS in timber seismic-resistant structures, masonry arch structures, long-span steel bridges, prefabricated/on-site extruded light-weight steel structures, fiber-reinforced cementitious composites structures, and fiber-reinforced polymer bridge decks. Additionally, advanced material design methods such as bioinspired design and structure construction technology of additive manufacturing are briefly reviewed and discussed to demonstrate how MIDCS can combine materials and structures. A unified strength-durability design theory is also introduced, which is a human-centric, interdisciplinary, and holistic approach to the description and development of any civil infrastructure and includes all processes directly involved in the life cycle of the infrastructure. Finally, this paper lays out future research directions for further development in the field.

关键词: integrated design and construction     fiber-reinforced concrete     fiber-reinforced polymer     light-weight steel structures     digital fabrication     composites    

Experimental study on GFRP pipes under axial compression

QIAN Peng, FENG Peng, YE Lieping

《结构与土木工程前沿(英文)》 2008年 第2卷 第1期   页码 73-78 doi: 10.1007/s11709-008-0013-y

摘要: Fiber reinforced polymer (FRP) is suitable for structures in corrosive environment and long-span light-weight structures due to its high-strength, light-weight, and anti-corrosive qualities. The behavior of pultruded glass fiber reinforced polymer (GFRP) pipes, which are the members of long-span lattice structures, under axial compression was investigated by tests. Short GFRP pipes were first tested to determine the basic mechanical properties. Then the stability of long GFRP pipes was studied by axially compressive tests in four groups with different slenderness ratios, twelve specimens totally. Based on the results of the tests and literature, the formula of the buckling load of composite pipes under axially compressive load was presented based on Perry formula. It can well predict the buckling failure load GFRP pipe under axial compression.

关键词: anti-corrosive     compression     different slenderness     corrosive environment     long-span light-weight    

面向高性能计算的自部署运行环境 Research Articles

邵明天,卢凯,张文喆

《信息与电子工程前沿(英文)》 2022年 第23卷 第6期   页码 845-857 doi: 10.1631/FITEE.2100016

摘要:

传统高性能计算系统提供了标准的预置环境来支持科学计算。然而,高性能计算的发展需要为越来越多应用提供支持,如人工智能、大数据等。标准的预设环境已无法满足这些多样化的要求。如果用户仍然在高性能计算系统上运行这些新兴应用程序,他们需要手动维护应用程序的特定依赖项(库、环境变量等),这增加了用户的开发和部署负担。此外,多用户模式也带来用户之间的隐私问题。像Docker和Singularity这样的容器可以封装作业的执行环境,但是在高度定制的高性能计算系统中,Docker和Singularity的跨环境应用部署是受限的。容器镜像的引入也给系统管理员增加了维护负担。针对上述问题,本文提出一种适用于高性能计算的自部署执行环境(SDEE)。SDEE结合了传统虚拟化和现代容器的优点,为用户提供了一个独立、可定制的环境(类似于虚拟机)。该用户是此环境中的根用户。用户开发和调试应用程序,并在此环境中部署其特殊的依赖项,然后可以通过传统高性能计算系统的作业管理系统,直接将作业加载到计算节点。作业及其依赖项将被自动分析、打包、部署和执行。该过程实现了透明、快速的作业部署,不仅减轻了用户负担,而且保护了用户隐私。实验表明,SDEE引入的开销可忽略不计,比Docker和Singularity都要低。

关键词: 运行环境;高性能计算;轻量化;隔离;Overlay    

海洋桥梁工程轻质、高强、耐久性结构材料现状及发展趋势研究

吴智深 ,刘加平 ,邹德辉 ,汪昕 ,史健喆

《中国工程科学》 2019年 第21卷 第3期   页码 31-40 doi: 10.15302/J-SSCAE-2019.03.014

摘要:

本文针对海洋环境下大跨桥梁突出的长期服役性能问题和轻量化需求,通过对轻质、高强、耐久的材料深入调研,总结了高性能钢、高性能混凝土及纤维增强复合材料的研究现状及发展趋势,介绍了上述材料在桥梁关键区域的针对性应用技术,并提出海洋桥梁工程轻质、高强、耐久材料发展的战略建议,以满足海洋桥梁工程高性能、长寿命、轻量化的需求,突破海洋环境下大跨桥梁的耐久和跨度瓶颈。

关键词: 海洋环境     大跨桥梁     高性能钢     高性能混凝土     纤维增强复合材料    

Empirical models and design codes in prediction of modulus of elasticity of concrete

Behnam VAKHSHOURI, Shami NEJADI

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 38-48 doi: 10.1007/s11709-018-0479-1

摘要: Modulus of Elasticity (MOE) is a key parameter in reinforced concrete design. It represents the stress-strain relationship in the elastic range and is used in the prediction of concrete structures. Out of range estimation of MOE in the existing codes of practice strongly affect the design and performance of the concrete structures. This study includes: (a) evaluation and comparison of the existing analytical models to estimating the MOE in normal strength concrete, and (b) proposing and verifying a new model. In addition, a wide range of experimental databases and empirical models to estimate the MOE from compressive strength and density of concrete are evaluated to verification of the proposed model. The results show underestimation of MOE of conventional concrete in majority of the existing models. Also, considering the consistency between density and mechanical properties of concrete, the predicted MOE in the models including density effect, are more compatible with the experimental results.

关键词: modulus of elasticity     normal strength normal weight concrete     empirical models     design codes     compressive strength     density    

Solving topology optimization problems by the Guide-Weight method

Xinjun LIU, Zhidong LI, Liping WANG, Jinsong WANG

《机械工程前沿(英文)》 2011年 第6卷 第1期   页码 136-150 doi: 10.1007/s11465-010-0126-6

摘要:

Finding a good solution method for topology optimization problems is always paid attention to by the research field because they are subject to the large number of the design variables and to the complexity that occurs because the objective and constraint functions are usually implicit with respect to design variables. Guide-Weight method, proposed first by Chen in 1980s, was effectively and successfully used in antenna structures’ optimization. This paper makes some improvement to it so that it possesses the characteristics of both the optimality criteria methods and the mathematical programming methods. When the Guide-Weight method is applied into topology optimization, it works very well with unified and simple form, wide availability and fast convergence. The algorithm of the Guide-Weight method and the improvement on it are described; two formulations of topology optimization solved by the Guide-Weight method combining with SIMP method are presented; subsequently, three numerical examples are provided, and comparison of the Guide-Weight method with other methods is made.

关键词: Guide-Weight method     topology optimization     SIMP method    

Characterization of soil low-molecular-weight organic acids in the Karst rocky desertification region

Xiaoliang LI, Xiaomin CHEN, Xia LIU, Lianchuan ZHOU, Xinqiang YANG

《环境科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 195-203 doi: 10.1007/s11783-012-0391-1

摘要: Soil low-molecular-weight (LMW) organic acids play important roles in the soil-forming process and the cycling of nutrients in Karst regions. In this study, we quantified the contents of LMW organic acids (including lactate, acetate, formate, malate, and oxalate) in soil solution over the Karst region of Guizhou Province, China using ion chromatography. The concentration of total LMW organic acids in topsoil solution ranged from 0.358 to 1.823 μmol·g , with an average of 0.912 μmol·g . The mean concentrations of lactate, acetate, formate, malate, and oxalate were 0.212±0.089, 0.302±0.228, 0.301±0.214, 0.014±0.018 and 0.086±0.118 μmol·g , respectively. There were also significant difference in the contents of these acids among four phases of rocky desertification, and their concentrations decreased with the aggravation of rocky desertification. The concentrations of the LMW organic acids were significantly positive correlated each other. Significant positive correlations were also observed among individual LMW organic acids in soil solution, and between them and soil available P, available K, exchangeable Ca, respectively. Furthermore, the concentrations of LMW organic acids were significantly positively correlated with inorganic anions (chlorides, nitrates, and sulfates) in Karst topsoil solution. Therefore, the concentrations of soil LMW organic acids might be one of driving force in the Karst rock desertification process in Guizhou Province.

关键词: Karst rocky desertification     low-molecular-weight (LMW) organic acids     distribution characteristics     soil    

Prediction of falling weight deflectometer parameters using hybrid model of genetic algorithm and adaptive

《结构与土木工程前沿(英文)》   页码 812-826 doi: 10.1007/s11709-023-0940-7

摘要: A falling weight deflectometer is a testing device used in civil engineering to measure and evaluate the physical properties of pavements, such as the modulus of the subgrade reaction (Y1) and the elastic modulus of the slab (Y2), which are crucial for assessing the structural strength of pavements. In this study, we developed a novel hybrid artificial intelligence model, i.e., a genetic algorithm (GA)-optimized adaptive neuro-fuzzy inference system (ANFIS-GA), to predict Y1 and Y2 based on easily determined 13 parameters of rigid pavements. The performance of the novel ANFIS-GA model was compared to that of other benchmark models, namely logistic regression (LR) and radial basis function regression (RBFR) algorithms. These models were validated using standard statistical measures, namely, the coefficient of correlation (R), mean absolute error (MAE), and root mean square error (RMSE). The results indicated that the ANFIS-GA model was the best at predicting Y1 (R = 0.945) and Y2 (R = 0.887) compared to the LR and RBFR models. Therefore, the ANFIS-GA model can be used to accurately predict Y1 and Y2 based on easily measured parameters for the appropriate and rapid assessment of the quality and strength of pavements.

关键词: falling weight deflectometer     modulus of subgrade reaction     elastic modulus     metaheuristic algorithms    

Photocatalysis: from solar light to hydrogen energy

《能源前沿(英文)》 2021年 第15卷 第3期   页码 565-567 doi: 10.1007/s11708-021-0784-6

A novel light fluctuation spectrum method for in-line particle sizing

Shouxuan QIN, Xiaoshu CAI, Li MA

《能源前沿(英文)》 2012年 第6卷 第1期   页码 89-97 doi: 10.1007/s11708-012-0176-z

摘要: This paper discusses two problems in in-line particle sizing when using light fluctuation method. First, by retrieving the ratio of particle concentrations at different time, the intensity of incident light is obtained. There exists narrow error between the calculated and pre-detected value of the intensity of incident light. Secondly, by combining spectrum analysis with Gregory’s theory, a multi-sub-size zone model is proposed, with which the relationship between the distribution of turbidity and the particle size distribution (PSD) can be established, and an algorithm developed to determine the distribution of turbidity. Experiments conducted in the laboratory indicate that the measured size distribution of pulverized coal conforms well with the imaging result.

关键词: in-line measurement     particle size distribution (PSD)     incident light intensity     particle concentration     light fluctuation    

Plasmonic light trapping for enhanced light absorption in film-coupled ultrathin metamaterial thermophotovoltaic

Qing NI, Hassan ALSHEHRI, Yue YANG, Hong YE, Liping WANG

《能源前沿(英文)》 2018年 第12卷 第1期   页码 185-194 doi: 10.1007/s11708-018-0522-x

摘要: Ultrathin cells have gained increasing attention due to their potential for reduced weight, reduced cost and increased flexibility. However, the light absorption in ultrathin cells is usually very weak compared to the corresponding bulk cells. To achieve enhanced photon absorption in ultrathin thermophotovoltaic (TPV) cells, this work proposed a film-coupled metamaterial structure made of nanometer-thick gallium antimonide (GaSb) layer sandwiched by a top one-dimensional (1D) metallic grating and a bottom metal film. The spectral normal absorptance of the proposed structure was calculated using the rigorous coupled-wave algorithm (RCWA) and the absorption enhancement was elucidated to be attributed to the excitations of magnetic polariton (MP), surface plasmon polariton (SPP), and Fabry-Perot (FP) resonance. The mechanisms of MP, SPP, and FP were further confirmed by an inductor-capacitor circuit model, dispersion relation, and phase shift, respectively. Effects of grating period, width, spacer thickness, as well as incidence angle were discussed. Moreover, short-circuit current density, open-circuit voltage, output electric power, and conversion efficiency were evaluated for the ultrathin GaSb TPV cell with a film-coupled metamaterial structure. This work will facilitate the development of next-generation low-cost ultrathin infrared TPV cells.

关键词: metamaterial     thermophotovoltaic     plasmonics     light trapping     selective absorption    

HQ in inland saline-alkaline water under different light qualities

《环境科学与工程前沿(英文)》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1479-2

摘要:

• Optimal growth of Chlorella in inland saline-alkaline water was achieved by blue LED.

关键词: Light quality     Chlorella     Inland saline-alkaline water     Fatty acid     Biodiesel property    

Evaluation of ICUs and weight of quality control indicators: an exploratory study based on Chinese ICU

《医学前沿(英文)》 2023年 第17卷 第4期   页码 675-684 doi: 10.1007/s11684-022-0970-x

摘要: This study aimed to explore key quality control factors that affected the prognosis of intensive care unit (ICU) patients in Chinese mainland over six years (2015−2020). The data for this study were from 31 provincial and municipal hospitals (3425 hospital ICUs) and included 2 110 685 ICU patients, for a total of 27 607 376 ICU hospitalization days. We found that 15 initially established quality control indicators were good predictors of patient prognosis, including percentage of ICU patients out of all inpatients (%), percentage of ICU bed occupancy of total inpatient bed occupancy (%), percentage of all ICU inpatients with an APACHE II score ≥15 (%), three-hour (surviving sepsis campaign) SSC bundle compliance (%), six-hour SSC bundle compliance (%), rate of microbe detection before antibiotics (%), percentage of drug deep venous thrombosis (DVT) prophylaxis (%), percentage of unplanned endotracheal extubations (%), percentage of patients reintubated within 48 hours (%), unplanned transfers to the ICU (%), 48-h ICU readmission rate (%), ventilator associated pneumonia (VAP) (per 1000 ventilator days), catheter related blood stream infection (CRBSI) (per 1000 catheter days), catheter-associated urinary tract infections (CAUTI) (per 1000 catheter days), in-hospital mortality (%). When exploratory factor analysis was applied, the 15 indicators were divided into 6 core elements that varied in weight regarding quality evaluation: nosocomial infection management (21.35%), compliance with the Surviving Sepsis Campaign guidelines (17.97%), ICU resources (17.46%), airway management (15.53%), prevention of deep-vein thrombosis (14.07%), and severity of patient condition (13.61%). Based on the different weights of the core elements associated with the 15 indicators, we developed an integrated quality scoring system defined as F score=21.35%×nosocomial infection management + 17.97%×compliance with SSC guidelines + 17.46%×ICU resources + 15.53%×airway management + 14.07%×DVT prevention + 13.61%×severity of patient condition. This evidence-based quality scoring system will help in assessing the key elements of quality management and establish a foundation for further optimization of the quality control indicator system.

关键词: critical care medicine     quality control     evaluation     exploratory factor analysis (EFA) model    

Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1484-1502 doi: 10.1007/s11705-023-2331-y

摘要: Various hydrophilic poly(ethylene-co-vinyl alcohol) (EVOH) were used herein to precisely control the structure and hydrodynamic properties of polysulfone (PSF) membranes. Particularly, to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol (VOH: 73%, 68%, 56%), the non-solvent-induced phase separation (NIPS) technique was used. Polyethylene glycol was used as a compatibilizer and as a porogen in N,N-dimethylacetamide. Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism. The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism. Accordingly, the addition of EVOH led to an increase in the rheology of the dopes. The resulting membranes exhibited a microporous structure, while the finger-like structures became more evident with increasing VOH content. The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics. Interestingly, the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m–2·h–1·bar–1, which was higher than that of pure PSF membranes (171 L·m–2·h–1·bar–1). In addition, PSF/EVOH32 rejected bovine serum albumin at a high rate (> 90%) and achieved a significant restoration of permeability. Finally, from the thermodynamic and hydrodynamic results, valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

关键词: polysulfone     blend modification     ultrafiltration membrane     formation hydrodynamics     poly(ethylene-co-vinyl alcohol) copolymer    

标题 作者 时间 类型 操作

Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

期刊论文

Materials-oriented integrated design and construction of structures in civil engineering—A review

期刊论文

Experimental study on GFRP pipes under axial compression

QIAN Peng, FENG Peng, YE Lieping

期刊论文

面向高性能计算的自部署运行环境

邵明天,卢凯,张文喆

期刊论文

海洋桥梁工程轻质、高强、耐久性结构材料现状及发展趋势研究

吴智深 ,刘加平 ,邹德辉 ,汪昕 ,史健喆

期刊论文

Empirical models and design codes in prediction of modulus of elasticity of concrete

Behnam VAKHSHOURI, Shami NEJADI

期刊论文

Solving topology optimization problems by the Guide-Weight method

Xinjun LIU, Zhidong LI, Liping WANG, Jinsong WANG

期刊论文

Characterization of soil low-molecular-weight organic acids in the Karst rocky desertification region

Xiaoliang LI, Xiaomin CHEN, Xia LIU, Lianchuan ZHOU, Xinqiang YANG

期刊论文

Prediction of falling weight deflectometer parameters using hybrid model of genetic algorithm and adaptive

期刊论文

Photocatalysis: from solar light to hydrogen energy

期刊论文

A novel light fluctuation spectrum method for in-line particle sizing

Shouxuan QIN, Xiaoshu CAI, Li MA

期刊论文

Plasmonic light trapping for enhanced light absorption in film-coupled ultrathin metamaterial thermophotovoltaic

Qing NI, Hassan ALSHEHRI, Yue YANG, Hong YE, Liping WANG

期刊论文

HQ in inland saline-alkaline water under different light qualities

期刊论文

Evaluation of ICUs and weight of quality control indicators: an exploratory study based on Chinese ICU

期刊论文

Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

期刊论文