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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

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一种用于隔热、阻燃和抑烟的可发性聚苯乙烯泡沫的高效绿色多孔黏合剂 Article

李蒙恩, 赵海波, 程金波, 汪婷, 付腾, 张爱泞, 王玉忠

《工程（英文）》 2022年第17卷第10期页码 151-160 doi: 10.1016/j.eng.2020.08.032

摘要：

为解决建筑保温用可发性聚苯乙烯（EPS）泡沫阻燃、抑烟和隔热之间的矛盾，设计制备了一种新型的基于植酸（PA）改性淀粉的绿色多孔生物基阻燃淀粉（FRS）涂层。FRS可同时起到阻燃剂和黏合剂的作用，自身具有开孔结构，可与EPS珠粒的封闭单元形成多级孔结构，使得所得FRS-EPS泡沫表现出隔热性能，导热率仅27.0 mW⋅(m⋅K)⁻¹。该FRS-EPS 泡沫表现出极低的热释放和烟释放速率，具有优异的阻燃性和抑烟性。比光密度低至121，比纯EPS降低了80.6%。FRS-EPS在垂直燃烧试验中也表现出自熄灭行为，极限氧指数（LOI）值高达35.5%。在酒精灯灼烧30 min 后，FRS-EPS的背部温度仅140 °C，具有优异的耐火性。阻燃机理研究表明，高温下FRS在凝聚相中形成了致密的富磷杂化屏障，气相中形成的含磷化合物实现了阻燃和抑烟。该工作为制备具有优异阻燃性、抑烟性和隔热性的聚合物泡沫提供了新思路。

关键词：生物基多孔涂层可发性聚苯乙烯泡沫低导热率阻燃性抑烟性

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Hormesis-like growth and photosynthetic physiology of marine diatom Bohlin exposed to polystyrene microplastics

《环境科学与工程前沿（英文）》 2022年第16卷第1期页码 2-2 doi: 10.1007/s11783-021-1436-0

摘要：

• Polystyrene microplastic caused hormesis-like effects in Phaeodactylum tricornutum.

关键词： Microplastics Marine microalgae Phaeodactylum tricornutum Bohlin Growth Photosynthetic pigments Chlorophyll fluorescence parameters

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Flow and thermal modeling of liquid metal in expanded microchannel heat sink

《能源前沿（英文）》页码 796-810 doi: 10.1007/s11708-023-0877-5

摘要： Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In this paper, it was found that expanded space at the top of fins could distribute the heat inside microchannels, reducing the temperature rise of coolant and heat sink. The orthogonal experiments revealed that expanding the top space of channels yielded similar temperature reductions to changing the channel width. The flow and thermal modeling of expanded microchannel heat sink (E-MCHS) were analyzed by both using the 3-dimensional (3D) numerical simulation and the 1-dimensional (1D) thermal resistance model. The fin efficiency of E-MCHS was derived to improve the accuracy of the 1D thermal resistance model. The heat conduction of liquid metal in Z direction and the heat convection between the top surface of fins and the liquid metal could reduce the total thermal resistance (R_t). The above process was effective for microchannels with low channel aspect ratio, low mean velocity (U_m) or long heat sink length. The maximum thermal resistance reduction in the example of this paper reached 36.0%. The expanded space endowed the heat sink with lower pressure, which might further reduce the pumping power (P). This rule was feasible both when fins were truncated (h₂ < 0, h₂ is the height of expanded channel for E-MCHS) and when over plate was raised (h₂ > 0).

关键词： liquid metal cooling heat sink expanded microchannel flow and thermal modeling

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Reliability mesh convergence analysis by introducing expanded control variates

Alireza GHAVIDEL, Mohsen RASHKI, Hamed GHOHANI ARAB, Mehdi AZHDARY MOGHADDAM

《结构与土木工程前沿（英文）》 2020年第14卷第4期页码 1012-1023 doi: 10.1007/s11709-020-0631-6

摘要： The safety evaluation of engineering systems whose performance evaluation requires finite element analysis is a challenge in reliability theory. Recently, Adjusted Control Variates Technique (ACVAT) has proposed by the authors to solve this issue. ACVAT uses the results of a finite element method (FEM) model with coarse mesh density as the control variates of the model with fine mesh and efficiently solves FEM-based reliability problems. ACVAT however does not provide any results about the reliability-based mesh convergence of the problem, which is an important tool in FEM. Mesh-refinement analysis allows checking whether the numerical solution is sufficiently accurate, even though the exact solution is unknown. In this study, by introducing expanded control variates (ECV) formulation, ACVAT is improved and the capabilities of the method are also extended for efficient reliability mesh convergence analysis of FEM-based reliability problems. In the present study, the FEM-based reliability analyses of four practical engineering problems are investigated by this method and the corresponding results are compared with accurate results obtained by analytical solutions for two problems. The results confirm that the proposed approach not only handles the mesh refinement progress with the required accuracy, but it also reduces considerably the computational cost of FEM-based reliability problems.

关键词： finite element reliability mesh convergence analysis expanded control variates

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The development of ultralightweight expanded perlite-based thermal insulation panel using alkali activator

Damla Nur ÇELİK; Gökhan DURMUŞ

《结构与土木工程前沿（英文）》 2022年第16卷第11期页码 1486-1499 doi: 10.1007/s11709-022-0881-6

摘要： The International Energy Agency (IEA) states that global energy consumption will increase by 53% by 2030. Turkey has 70% of the world’s perlite reserves, and in order to reduce energy consumption a thermal insulation panel was developed in Turkey using different particle sizes of expanded perlite (EP). In this study, 0–1.18 mm (powder) and 0–3 mm (granular) EP particle sizes were selected, since they have the lowest thermal conductivity coefficients among all the particle sizes. In addition, an alkali activator solution was used as a binder in the mixtures. The alkaline activator solution was obtained by mixing sodium hydroxide solution (6, 8, 10, and 12 mol·L⁻¹) and sodium silicate (Module 3) at the different ratios of Na₂SiO₃ to NaOH of 1, 1.5, 2, and 2.5. This study aimed to experimentally determine the optimum binder and distribution ratio of EP, with the lowest coefficient of thermal conductivity and the lowest density. The lowest thermal conductivity and the lowest density were determined as 0.04919 W·m⁻¹·K⁻¹ and 133.267 kg/m³, respectively, in the sample prepared with 83.33% powder-size EP, 6 mol·L⁻¹ sodium hydroxide solution, and ratio of Na₂SiO₃ to NaOH of 1.5. The density, thermal conductivity, and compressive strength of the sample showed the same trends of behavior when the Na₂SiO₃ to NaOH ratio was increased. In addition, the highest compressive strength was measured in 12 mol·L⁻¹ NaOH concentration regardless of particle size. In conclusion, the study predicts that the EP-based thermal insulation panel can be used as an insulation material in the construction industry according to the TS825 Thermal Insulation Standard.

关键词： expanded perlite alkali activator thermal insulation panel thermal conductivity

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硝酸铵膨化技术及应用

吕春绪

《中国工程科学》 2000年第2卷第2期页码 60-63

摘要：

硝酸铵膨化技术是一创新技术，创新设计的指导思想是硝酸铵自敏化，硝酸铵自敏化的提出是对国内外传统方法的突破。实施自敏化的技术途径是硝酸铵的膨化，其实质是表面活性技术在粉状炸药中的应用，是一个强制析晶的物理化学过程。文章重点讨论了硝酸铵膨化机理及膨化硝酸铵的技术特征，显示其独特的优点。硝酸铵膨化技术主要应用是岩石膨化硝铵炸药，给出了岩石膨化硝铵炸药的爆炸与物理特征数据，并与其它工业炸药做了比较。同时也推广应用在煤矿许用型炸药中。

关键词：膨化硝酸铵岩石炸药微结构机理

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Application of the expanded distinct element method for the study of crack growth in rock-like materials

Lei YANG, Yujing JIANG, Bo LI, Shucai LI, Yang GAO

《结构与土木工程前沿（英文）》 2012年第6卷第2期页码 121-131 doi: 10.1007/s11709-012-0151-0

摘要： The expanded distinct element method (EDEM) was used to investigate the crack growth in rock-like materials under uniaxial compression. The tensile-shear failure criterion and the Griffith failure criterion were implanted into the EDEM to determine the initiation and propagation of pre-existing cracks, respectively. Uniaxial compression experiments were also performed with the artificial rock-like samples to verify the validity of the EDEM. Simulation results indicated that the EDEM model with the tensile-shear failure criterion has strong capabilities for modeling the growth of pre-existing cracks, and model results have strong agreement with the failure and mechanical properties of experimental samples. The EDEM model with the Griffith failure criterion can only simulate the splitting failure of samples due to tensile stresses and is incapable of providing a comprehensive interpretation for the overall failure of rock masses. Research results demonstrated that sample failure primarily resulted from the growth of single cracks (in the form of tensile wing cracks and shear secondary cracks) and the coalescence of two cracks due to the growth of wing cracks in the rock bridge zone. Additionally, the inclination angle of the pre-existing crack clearly influences the final failure pattern of the samples.

关键词： expanded distinct element method (EDEM) crack growth rock-like material tensile-shear failure criterion Griffith failure criterion mechanical and failure behavior

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Synthesis of mid-dicarboxy polystyrene by ATRP and formation of ionic-bonded supramolecules

YU Tao, WANG Yun, LU Dairen, BAI Ruke, LU Weiqi

《化学科学与工程前沿（英文）》 2007年第1卷第2期页码 140-145 doi: 10.1007/s11705-007-0026-4

摘要： Dimethyl 4, 6-bis (bromomethyl) isophthalate was synthesized by bromomethylation, oxidation, esterification and bromination of 1, 3-dimethylbenzene. This was used to initiate the atom transfer radical polymerization of styrene successfully. Results showed that the process had some of the good characteristics of controlled/living free radical polymerization. The molecular weight of the obtained polymer increased linearly with monomer conversion, its molecular weight distribution was very narrow, and a linear relationship between ln([]/[]) and polymerization time was found. A well-defined novel structural polystyrene containing two ester groups in the mid-main chain was prepared with controlled molecular weight and narrow polydispersity. The structure of the polymer was confirmed by H-NMR spectra. After being hydrolyzed, dicarboxy polystyrene was obtained and used to form ionic-bonded supramolecules with 1-dodecanamine as a model of the star-shaped supramolecules. The supramolecules formed were characterized by Fourier transform infrared (FTIR) spectrum.

关键词： controlled molecular conversion bromination relationship isophthalate

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膨化硝酸铵自敏化理论研究

吕春绪

《中国工程科学》 2000年第2卷第11期页码 73-77

摘要：

膨化硝酸铵自敏化理论是膨化技术发明的核心，它是基于热点理论把微气泡植入硝酸铵炸药中。微气泡临界热点温度热力学计算为自敏化提供理论依据。与普通硝酸铵及珍珠岩相比较，微气泡在膨化硝酸铵内适当的分布为自敏化成功提供了有力的保证。

关键词：膨化硝酸铵自敏化微气泡

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A new polystyrene-latex-based and EPS-containing synthetic sludge

Ling-Ling Wang, Shan Chen, Hai-Ting Zheng, Guo-Qing Sheng, Zhi-Jun Wang, Wen-Wei Li, Han-Qing Yu

《环境科学与工程前沿（英文）》 2012年第6卷第1期页码 131-139 doi: 10.1007/s11783-011-0390-7

摘要： Since the living microorganisms in activated sludge continuously change, it is difficult to conduct controlled experiments and achieve reproducible results for evaluating sludge characteristics. Synthetic sludge, as a chemical surrogate to activated sludge, could be used to investigate the sludge physicochemical properties, and it is desirable to prepare synthetic sludge with similar structure and properties to real activated sludge to explore the flocculation and settlement processes in activated sludge systems. In this work, a high-strength synthetic sludge was prepared with functional polystyrene latex particles as the framework and extracellular polymeric substances (EPS) to modify its surface. The flocculation and settling characteristics of the microspheres and the prepared synthetic sludge were tested. Compared with other three functional polystyrene latex microspheres, the synthetic sludge prepared with EPS-modified polystyrene latex microspheres showed good settling characteristics and a significantly higher strength. They could be used for studying the physicochemical properties of activated sludge.

关键词： activated sludge extracellular polymeric substances (EPS) flocculation polystyrene latex particles synthetic sludge

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Influence of influent on anaerobic ammonium oxidation in an Expanded Granular Sludge Bed-Biological Aerated

Daijun ZHANG, Cui BAI, Ting TANG, Qing YANG

《环境科学与工程前沿（英文）》 2011年第5卷第2期页码 291-297 doi: 10.1007/s11783-010-0270-6

摘要： Shortcut nitrification-denitrification, anaerobic ammonium oxidation (ANAMMOX), and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter (EGSB-BAF) integrated system. As fed different synthetic wastewater with chemical oxygen demand (COD) of 300–1200 mg·L and of 30–120 mg·L at the outer recycle ratio of 200%, the influence of influent on ANAMMOX in the integrated system was investigated in this paper. The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX; however, when an influent with the low concentration of COD was used, the opposite changes could be observed. Higher influent concentration favored ANAMMOX when the COD concentration of influent was fixed. Therefore, low ratio would decrease competition for nitrite between ANAMMOX and denitrification, which was favorable for reducing the negative effect of organic COD on ANAMMOX. The good performance of the integrated system indicated that the bacterial community of denitrification, ANAMMOX, and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent.

关键词： Expanded Granular Sludge Bed-Biological Aerated Filter (EGSB-BAF) integrated system the influence of influent anaerobic ammonium oxidation (ANAMMOX) shortcut nitrification-denitrification methano-genesis

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扩大乙烯装置原料来源的思考与实践

曹湘洪

《中国工程科学》 2001年第3卷第5期页码 35-43

摘要：

从烃类原料裂解制乙烯的裂解性能和烃类馏份馏程及组成相关研究结果出发，提出了与世界乙烯原料轻质化的大趋势不同的扩大乙烯原料来源的思路：大庆原油的重馏份油即常三、减一线油和减二、减三线油酮苯脱蜡副产的蜡下油可以作乙烯原料。总结了该原料性能测试、模拟裂解炉评价及工业装置上应用的结果，证明该原料裂解时有较高的乙烯收率，也能保证裂解炉较长的运行周期，有明显的经济效益。

关键词：乙烯原料来源

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Effect of nitrobenzene on the performance and bacterial community in an expanded granular sludge bed

Jun Li, Wentao Li, Gan Luo, Yan Li, Aimin Li

《环境科学与工程前沿（英文）》 2019年第13卷第1期 doi: 10.1007/s11783-019-1090-y

摘要：

Less than 50 mg/L nitrobenzene brought little effect on anaerobic sulfate reduction.

Kinetics of sulfate reduction under different nitrobenzene contents was studied.

Increased nitrobenzene contents greatly changed the bacterial community structure.

Genus Desulfovibrio played the key role in anaerobic sulfate reduction process.

关键词： Nitrobenzene (NB) Sulfate-reducing bacteria (SRB) Bacterial community Sulfate reduction High-throughput sequencing

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Photocatalytic activity of ZnO films with micro-grid structure

Chunzhi LI , Wenwen WANG , Junying ZHANG , Hailing ZHU , Weiwei ZHANG , Tianmin WANG ,

《环境科学与工程前沿（英文）》 2009年第3卷第3期页码 289-293 doi: 10.1007/s11783-009-0034-3

摘要： A layer of zinc oxide (ZnO) micro-grid was deposited on the surface of ZnO film using the DC reactive magnetron sputtering method and the micro-sphere lithography technique on glass substrates. Samples of this layer were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and ultraviolet-visible light spectroscopy. X-ray diffraction showed the high crystallinity of ZnO film and the regular arrangement of the micro-grid. The micro-grid ZnO has a lower specular reflection and a higher diffuse reflection, allowing incident light to reflect two or three times to enhance the usage of light. Photocatalytic degradation experiments on methylene blue using both ZnO micro-grid and ordinary film showed that the ZnO micro-grid has better photocatalytic properties than ordinary film. The ZnO micro-grid enhanced the photocatalytic efficiency of ZnO film by 28% with a degradation time of 300min.

关键词： Photocatalysis ZnO micro-grid polystyrene latex spheres template diffuse reflection