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Moving policy and regulation forward for single-use plastic alternatives

《环境科学与工程前沿（英文）》 2021年 第15卷 第3期 doi: 10.1007/s11783-021-1423-5

摘要： Single-use plastics are often used once or cannot be reused for extended periods. They are widely consumed with the rapid development of social economy. The waste generated by single-use plastics threatens ecosystem health by entering the environment and ultimately restricts sustainable human development. The innovation of sustainable and environmentally friendly single-use plastic alternative materials and the joint participation of governments, enterprises and the public are promising technologies and management approaches that can solve the problem of single-use plastics wastes. The development of single-use plastic alternative products can be promoted fundamentally only by improving relevant legislation and standards, providing differentiated industrial policies, encouraging scientific and technological innovation and expanding public participation.

关键词： Single-use plastic alternatives     Policy     Regulation     Sustainable development    

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The road to sustainable use and waste management of plastics in Portugal

《环境科学与工程前沿（英文）》 2022年 第16卷 第1期   页码 5-5 doi: 10.1007/s11783-021-1439-x

摘要：

• Portugal recycles 34% of the 40 kg/hab year of plastic packaging waste.

关键词： Single-use plastics     Plastic packaging     Plastic waste     Waste management     Waste shipment     Lightweight plastic bags    

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Investigating the role of exiting vehicles and turn indicator usage in gap acceptance at single-lane

Nathan P. BELZ

《结构与土木工程前沿（英文）》 2017年 第11卷 第1期   页码 8-16 doi: 10.1007/s11709-016-0365-7

摘要： Roundabouts are becoming a preferred form of intersection control type due to their safety and capacity benefits. Yield control at roundabout entries inherently reduces fuel consumption and emissions when compared to other conventional intersection types. However, these benefits can be limited by poor driver behavior and judgment when entering the roundabout. This research addresses the nature of gap distributions and use of turn indicators by exiting vehicles at three single-lane roundabouts in Vermont, New York, and Alaska. Presented here is a comparison of vehicle headways measured at two different locations in each roundabout. Rejected headways are analyzed in the context of priority abstaining events when entering drivers yield to vehicles exiting on the same leg of the roundabout suggesting that “true” critical gaps are being overestimated. Results indicate that exiting vehicles, particularly those that do not use their turn indicators when departing from the major-stream of traffic have an influence on the entry decision of drivers on the same approach. This behavior is of particular concern for intersection efficiency (i.e., delay) and sustainability (i.e., excess fuel consumption and emissions). Results prompt the consideration of more consistent guidance on and enforcement of turn indicator use during roundabout negotiations.

关键词： roundabouts     exiting vehicles     turn indicator use     headways    

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Current scenario and challenges of plastic pollution in Bangladesh: a focus on farmlands and terrestrial

《环境科学与工程前沿（英文）》 2023年 第17卷 第6期 doi: 10.1007/s11783-023-1666-4

摘要：

● A global snapshot of plastic waste generation and disposal is analysed.

关键词： Plastic waste     Farmlands     Terrestrial ecosystem     Marine life    

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广义塑性力学及其运用

郑颖人,孔亮

《中国工程科学》 2005年 第7卷 第11期   页码 21-36

摘要：

分析了经典塑性力学用于岩土类材料的问题，它采用了3个不符合岩土材料变形机制的假设。从固体力学原理直接导出广义塑性位势理论，将经典塑性力学改造为更一般的塑性力学——广义塑性力学。广义塑性力学采用了塑性力学中的分量理论，能反映应力路径转折的影响，并避免了采用正交流动法则所引起的过大剪胀等不合理现象，也不会产生当前非关联流动法则中任意假定塑性势面引起的误差。给出了广义塑性力学的屈服面理论、硬化定律和应力-应变关系，并建立了考虑应力主轴旋转的广义塑性位势理论。屈服条件是状态参数，也是试验参数，只能由试验给出。应用表明，广义塑性力学可作为岩土材料的建模理论，还可应用于诸如极限分析等土力学的诸多领域，具有广阔的应用前景。

关键词： 岩土塑性力学     广义塑性力学     塑性势     屈服面     本构模型    

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Effects of natural zeolite and sulfate ions on the mechanical properties and microstructure of plastic

《结构与土木工程前沿（英文）》 2022年 第16卷 第1期   页码 86-98 doi: 10.1007/s11709-021-0793-x

摘要： One of the strategic materials used in earth-fill embankment dams and in modifying and preventing groundwater flow is plastic concrete (PlC). PlC is comprised of aggregates, water, cement, and bentonite. Natural zeolite (NZ) is a relatively abundant mineral resource and in this research, the microstructure, unconfined strength, triaxial behavior, and permeability of PlC made with 0%, 10%, 15%, 20%, and 25% replacement of cement by NZ were studied. Specimens of PIC-NZ were subjected to confined conditions and three different confining pressures of 200, 350, and 500 kPa were used to investigate their mechanical behavior and permeability. To study the effect of sulfate ions on the properties of PlC-NZ specimens, the specimens were cured in one of two different environments: normal condition and in the presence of sulfate ions. Results showed that increasing the zeolite content decreases the unconfined strength, elastic modulus, and peak strength of PlC-NZ specimens at the early ages of curing. However, at the later ages, increasing the zeolite content increases unconfined strength as well as the peak strength and elastic modulus. Specimens cured in the presence of sulfate ions indicated lower permeability, higher unconfined strength, elastic modulus, and peak strength due to having lower porosity.

关键词： plastic concrete     sulfate resistance     natural zeolite     triaxial compression test     SEM     permeability    

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Preventing masks from becoming the next plastic problem

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1413-7

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Antimicrobial use in food animal production: situation analysis and contributing factors

Ziping WU

《农业科学与工程前沿（英文）》 2018年 第5卷 第3期   页码 301-311 doi: 10.15302/J-FASE-2018207

摘要：

By measuring the quantity and ways in which antimicrobials are used, and reviewing different technical and socioeconomic factors influencing antimicrobial use at farm level, this study discusses the main knowledge gaps in antimicrobial use in food animal production and provides recommendations for future research and policy development. The review reveals that antimicrobial use in food animals exhibit strong regional and species differences, and there are still large information gaps concerning the current state of antimicrobial use. Factors associated with animal health (including antimicrobial resistance), animal health improvement, economic costs and benefits relevant to animal diseases, and potential technological alternatives or alternative systems all have an impact on antimicrobial use on the farm. There is a clear need to resolve the data gap by monitoring antimicrobial use and developing an analytical framework to better understand farmer behaviors under different technical, economic and environmental circumstances.

关键词： antimicrobial use     drivers for antimicrobial use     food animal production    

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Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 318-330 doi: 10.1007/s11709-017-0420-z

摘要：

The objective of this study is, to interpret the influence of reinforced concrete walls addition in reinforced concrete frame structures considering behavior laws that reflects the actual behavior of such structures, by means of Castem2000computer code (pushover analysis). A finite element model is proposed in this study, using the TAKEDA modified behavior model with Timoshenko beams elements. This model is validated initially on experimental model. Then the work has focused on the behavior of a RC frame with 3 levels and three bays to better visualize the behavior of plastic hinges. Once the plastic hinge control parameters are identified (plastic rotation, ultimate curvature), a strengthening by introduction of reinforced concrete walls (RC/wall) at the ends of the reinforced concrete frame (RC/frame) has been performed. The results show that these RC walls significantly improve the behavior, by a relocation of efforts towards the central part of the beams.

关键词： RC/frame     RC/wall     moment curvature     plastic rotation     plastic hinge     pushover analysis     global models    

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Influence of recycled polyethylene terephthalate fibres on plastic shrinkage and mechanical properties

Necat ÖZAŞIK; Özgür EREN

《结构与土木工程前沿（英文）》 2022年 第16卷 第6期   页码 792-802 doi: 10.1007/s11709-022-0849-6

摘要： Polyethylene terephthalate bottles production has drastically increased year after year due to high versatility of polyethylene terephthalate plastics and considerable consumption of beverages. In tandem with that increase, the major concern of society has been the improper disposal of this non-biodegradable material to the environment. To deal with this concern, recycled polyethylene terephthalate bottles were incorporated in concrete as fibre reinforcements in this study. The objective of this research is to evaluate the mechanical properties of recycled polyethylene terephthalate fibre reinforced concrete (RPFRC) in comparison with control concrete without fibres. polyethylene terephthalate fibres with three different diameters (0.45, 0.65, and 1.0 mm) and two lengths (20 and 30 mm) were added at various proportions (0.5%, 1.0%, 1.5% and 2.0%) by volume of concrete in order to determine the effect of fibres initially on compressive, flexural and splitting tensile strengths of concrete. The results revealed that none of the fibres have detrimental effects up to 1% volume fraction, however further addition caused slight reductions on mechanical properties in some conditions. Plastic shrinkage resistance and impact resistance tests were also performed according to related standards. Polyethylene terephthalate fibres were observed to have marked improvements on those properties. Such a good performance could be attributed primarily to the bridging effect of fibres.

关键词： recycled PET     fibre-reinforced concrete     mechanical properties     plastic shrinkage     impact energy    

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Several basic problems in plastic theory of geomaterials

Yuanxue LIU, Jiawu ZHOU, Zhongyou LI, Chen CHEN, Yingren ZHENG

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 81-84 doi: 10.1007/s11709-009-0016-3

摘要： Based on the basic mechanical properties of geomaterials, it was proven that the Drucker Postulate and the classical theory of plasticity can not be applied to geomaterials. Moreover, several basic problems of plastic theory of geomaterials were discussed. Based on the strict theoretical analysis, the following have been proven: the single yield surface model based on the classical theory of plasticity is unsuitable for geomaterials whether the rule of associated flow is applied or not; the yield surface of geomaterials is not unique, and its number is the same as the freedoms of plastic strain increment; the yield surface is not convex; and the rule of associated flow is unsuitable for geomaterials.

关键词： constitutive relation     geomaterials     classial plastic theory     Drucker Postulate     yield surface     flow rule    

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Modeling of bentonite/sepiolite plastic concrete compressive strength using artificial neural network

Ali Reza GHANIZADEH, Hakime ABBASLOU, Amir Tavana AMLASHI, Pourya ALIDOUST

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 215-239 doi: 10.1007/s11709-018-0489-z

摘要： Plastic concrete is an engineering material, which is commonly used for construction of cut-off walls to prevent water seepage under the dam. This paper aims to explore two machine learning algorithms including artificial neural network (ANN) and support vector machine (SVM) to predict the compressive strength of bentonite/sepiolite plastic concretes. For this purpose, two unique sets of 72 data for compressive strength of bentonite and sepiolite plastic concrete samples (totally 144 data) were prepared by conducting an experimental study. The results confirm the ability of ANN and SVM models in prediction processes. Also, Sensitivity analysis of the best obtained model indicated that cement and silty clay have the maximum and minimum influences on the compressive strength, respectively. In addition, investigation of the effect of measurement error of input variables showed that change in the sand content (amount) and curing time will have the maximum and minimum effects on the output mean absolute percent error (MAPE) of model, respectively. Finally, the influence of different variables on the plastic concrete compressive strength values was evaluated by conducting parametric studies.

关键词： bentonite/sepiolite plastic concrete     compressive strength     artificial neural network     support vector machine     parametric analysis    

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Predetermination of potential plastic hinges on reinforced concrete frames using GFRP reinforcement

Dominik KUERES; Dritan TOPUZI; Maria Anna POLAK

《结构与土木工程前沿（英文）》 2022年 第16卷 第5期   页码 624-637 doi: 10.1007/s11709-022-0832-2

摘要： In the past, glass fiber-reinforced polymer (GFRP)-reinforcement has been successfully applied in reinforced concrete (RC) structures where corrosion resistance, electromagnetic neutrality, or cuttability were required. Previous investigations suggest that the application of GFRP in RC structures could be advantageous in areas with seismic activity due to their high deformability and strength. However, especially the low modulus of elasticity of GFRP limited its wide application as GFRP-reinforced members usually exhibit considerably larger deformations under service loads than comparable steel-reinforced elements. To overcome the aforementioned issues, the combination of steel and GFRP reinforcement in hybrid RC sections has been investigated in the past. Based on this idea, this paper presents a novel concept for the predetermination of potential plastic hinges in RC frames using GFRP reinforcement. To analyze the efficiency of the concept, nonlinear finite element simulations were performed. The results underscore the high efficiency of hybrid steel-GFRP RC sections for predetermining potential plastic hinges on RC frames. The results also indicate that the overall seismic behavior of RC structures could be improved by means of GFRP as both the column base shear force during the seismic activity as well as the plastic deformations after the earthquake were considerably less pronounced than in the steel-reinforced reference structure.

关键词： glass fiber-reinforced polymer     GFRP     hybrid section     plastic hinge     seismic design     reinforced concrete    

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Multi-Component Resource Recycling from Waste Light-Emitting Diode Under Hydrothermal Condition: Plastic

Yongliang Zhang,Lu Zhan,Zhenming Xu,

《工程（英文）》 doi: 10.1016/j.eng.2023.04.008

摘要： Light emitting diodes (LEDs) have accounted for most of the lighting market as the technology matures and costs continue to reduce. As a new type of e-waste, LED is a double-edged sword, as it contains not only precious and rare metals but also organic packaging materials. In previous studies, LED recycling focused on recovering precious and strategic metals while ignoring harmful substances such as organic packaging materials. Unlike crushing and other traditional methods, hydrothermal treatment can provide an environment-friendly process for decomposing packaging materials. This work developed a closed reaction vessel, where the degradation rate of plastic polyphthalamide (PPA) was close to 100%, with nano-TiO2 encapsulated in plastic PPA being efficiently recovered, while metals contained in LED were also recycled efficiently. Besides, the role of water in plastic PPA degradation that has been overlooked in current studies was explored and speculated in detail in this work. Environmental impact assessment revealed that the proposed recycling route for waste LED could significantly reduce the overall environmental impact compared to the currently published processes. Especially the developed method could reduce more than half the impact of global warming. Furthermore, this research provides a theoretical basis and a promising method for recycling other plastic-packaged e-waste devices, such as integrated circuits.

关键词： Waste LED     Hydrothermal treatment     Recycling     Plastic PPA degradation     Packaging materials    

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density measurement for plastic injection molding via ultrasonic technology

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0714-2

摘要： Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization. Therefore, in-situ density measurement is of great interest and has significant application value. The existing methods, such as pressure−volume−temperature (PVT) method, have the shortages of time-delay and high cost of sensors. This study is the first to propose an in-situ density measurement method using ultrasonic technology. The analyses of the time-domain and frequency-domain signals are combined in the proposed method. The ultrasonic velocity is obtained from the time-domain signals, and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals. Experiments with different process conditions are conducted, including different melt temperature, injection speed, material, and mold structure. Results show that the proposed method has good agreement with the PVT method. The proposed method has the advantages of in-situ measurement, non-destructive, high accuracy, low cost, and is of great application value for the injection molding industry.

关键词： ultrasonic measurement     melt density     in-situ measurement     injection molding    

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标题 作者 时间 类型 操作

Moving policy and regulation forward for single-use plastic alternatives

期刊论文

The road to sustainable use and waste management of plastics in Portugal

期刊论文

Investigating the role of exiting vehicles and turn indicator usage in gap acceptance at single-lane

Nathan P. BELZ

期刊论文

Current scenario and challenges of plastic pollution in Bangladesh: a focus on farmlands and terrestrial

期刊论文

广义塑性力学及其运用

郑颖人,孔亮

期刊论文

Effects of natural zeolite and sulfate ions on the mechanical properties and microstructure of plastic

期刊论文

Preventing masks from becoming the next plastic problem

期刊论文

Antimicrobial use in food animal production: situation analysis and contributing factors

Ziping WU

期刊论文

Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

期刊论文

Influence of recycled polyethylene terephthalate fibres on plastic shrinkage and mechanical properties

Necat ÖZAŞIK; Özgür EREN

期刊论文

Several basic problems in plastic theory of geomaterials

Yuanxue LIU, Jiawu ZHOU, Zhongyou LI, Chen CHEN, Yingren ZHENG

期刊论文

Modeling of bentonite/sepiolite plastic concrete compressive strength using artificial neural network

Ali Reza GHANIZADEH, Hakime ABBASLOU, Amir Tavana AMLASHI, Pourya ALIDOUST

期刊论文

Predetermination of potential plastic hinges on reinforced concrete frames using GFRP reinforcement

Dominik KUERES; Dritan TOPUZI; Maria Anna POLAK

期刊论文

Multi-Component Resource Recycling from Waste Light-Emitting Diode Under Hydrothermal Condition: Plastic

Yongliang Zhang,Lu Zhan,Zhenming Xu,

期刊论文

density measurement for plastic injection molding via ultrasonic technology

期刊论文