Co-pyrolysis characteristics of typical components of waste plastics in a falling film pyrolysis reactor

Waste plastics mainly come from MSW and usually exist in the form of mixed plastics. During the co-pyrolysis process of mixed plastics, various plastic components have different physicochemical properties and reaction mechanisms. Considering the high viscosity and low thermal conductivity of molten plastics, a falling film pyrolysis reactor was selected to explore the rapid co-pyrolysis process of typical plastic components(PP, PE and PS).The oil and gas yields and the compositions of pyrolysis products of the three components under different ratios at pyrolysis temperatures were analyzed to explore the co-pyrolysis characteristics of PP, PE, and PS. The study is of great significance to the recycling of waste plastics.

Effect of PCEs with Different Functional Groups on the Performance of Cement Paste

The adsorption behaviors and dispersing properties of polycarboxylate superplasticizer(PCE) with different functional groups were systematically analyzed to reveal the theory and methods of modifying PCE molecular structures and regulating PCE performances. By substituting carboxylic groups with sulfonic groups, ester groups or acylamino groups, respectively, modified PCEs with different functional groups were synthesized. Results show that introducing low amount of ester groups or sulfonic groups into the PCE molecules has no negative effects on the fluidity of cement paste, while introducing acylamino groups into PCE molecules significantly weakens the fluidity of cement paste. At low amount(when the molar ratio of sodium methallyl sulfonate to TPEG is lower than 0.4), the rapid adsorption of sulfonic groups onto the cement particles contributes to the high dispersing performance of the sulfonic group modified PCEs. When the substitution ratio of acrylic acid by sulfonic acid is higher than 0.4, the viscosity and the yield stress of cement paste increases sharply. Redundant sulfonic groups lead to the excessive charge density of the PCE, which contributes to the inhomogeneous adsorption on the cement grains and hence results in the decline of the dispersing performance. Substitution of carboxylic group by acylamino group or ester group slightly changes the viscosity as well as the yield stress of cement paste. Introducing sulfonic group into PCE molecule improves the adsorption behavior of PCEs, while introducing ester group or acylamino group into PCE depresses the adsorption properties.

Effects of Organosilane-modified PCE on the Fluidity and Hydration Properties of Cement-Fly Ash Composite Binder

Effects of organosilane-modified PCE (OS-PCE) on the fluidity and the hydration properties of cement-fly ash (FA) composite binder were systematically analyzed.The experimental results show that OS-PCE possesses respectively 36.98% and 36.67% higher saturated adsorption amount on cement and FA,in comparison with ordinary PCE,and can contribute to higher fluidity of cement-FA composite binder.The addition of OS-PCE retards hydration process of cement-FA composite binder proportionally with the dosage of OS-PCE,but promotes the hydration kinetics of the composite binder.The reactivity enhancement is attributed to the well-dispersed FA by OS-PCE,which provides more nucleation sites for the reaction of heterogeneous C-S-H and enhances the contact with water to react with CH forming pozzolanic C-S-H.Well-distributed hydration products are exhibited in the hardened binder added with OS-PCE,with a large number of hydrated gels uniformly fill in the pores and gaps,which improves the compaction of the hardened structure.

From landscape urbanism to ecological urbanism:Origin and development

Based on the origin and development of landscape urbanism,with several representative cases,this paper introduces the origin of ecological urbanism,as well as the main concepts and strategies,and then compared the changes from Landscape Urbanism to Ecological Urbanism.At last,this paper discusses its enlightenment on China’s urban construction and landscape development with the focus on the actual situation in China.

Exploring the Linkage between Land Use Type and Stream Water Quality of an Estuarine Island Applying GWR Model: A Case Study of Chongming, Shanghai

To understand the spatial correlations between land use type and water quality of an estuarine island is particularly essential to maintain its original ecological environment. Chongming Island is experiencing a rapid urbanization and agriculture land sprawl during the last decades, especially with the growth of agro-industry and the extension of old style residences. As a consequence, surface run-off from agricultural activities and domestic sewage discharge has a various linkage with stream water quality on the island. This study applied ageographical weight regression model approach to recognize the significance of the relationship between water quality and multiple land use. We also evaluated their spatial correlations which normally hidden from other traditional regression methods. The results reveal that the water quality of less-developed areas on Chongming Island was easily affected by land use types compared with other regions, TN, TP, BOD5, COD were shown as the most significant responses among all the water quality indicators. Green land and water area had a reduced effect on nutrients, expansion of industrial land would continuously make a contribution of pollutants to the water environment. Suggestions should therefore be taken into consideration during the process of development planning, in order to prevent water contamination.

单圆盾构法错缝隧道结构变形的健康评估综合分析（英文）

结构变形是隧道结构性能评估的重要依据,然而由于隧道结构具有纵向线性、横向截面大的特点,难以通过室内模型试验或者远行试验来研究结构变形与结构损伤的关系。以长三角某单圆盾构法错缝隧道事故案例为依托,通过研究结构变形、管片裂缝、接缝变形等病害特点及与隧道截面椭圆度的相关性,综合分析了隧道病害类型及检测方法。研究结果表明,椭圆度与各隧道病害指标均表现出很强的相关性,可以用来描述隧道病害程度的重要指标。若椭圆度小于0.5%,则隧道可以被认为处于完全健康的状态。但是如果椭圆度超过0.77%,则隧道处于严重的破坏状态。成果对完善盾构隧道相关规范,以及对形成运营期隧道维修养护标准有重要的意义。

信号处理及支持向量机在沥青路面横缝检测中的应用

基于振动的路面状况监测应用越来越广泛,然而,该类方法多关注平整度及明显异常,缺乏针对不显著的横向裂缝的研究。因此,本文借助信号处理技术及支持向量机(SVM),提出一种新颖的基于车辆振动的横向裂缝识别方法。对横向开裂路段和无裂缝路段的车辆振动信号在时域、频域和小波域进行了分析,旨在找到可以区分路面开裂与否的振动信号参数。这些参数共形成了8个SVM分类模型,保留具有最高准确度和F1分数的分类模型,该模型考虑的特征参数包括车辆速度、加速度极差、相对标准差、最大傅里叶系数和小波系数,据此建立了一个开裂-未开裂的分类器。然后在2292个路段上应用了该分类器,结果显示,识别准确度和F1分数分别为97.25%和85.25%。本文提出的横缝识别方法与已有的基于智能手机识别IRI和其他路面病害的方法可形成一个综合路面状况识别系统。

Effects of Different States of Fe on Anaerobic Digestion:A Review

Anaerobic digestion is widely used in the treatment of industrial wastewater,excess activated sludge,municipal waste,crop straw and livestock manure,with the functions of environmental protection and energy recovery. This review summarizes and evaluates the present knowledge of effects of different states of Fe( ZVI,Fe( II),Fe( III)) on hydrogen and methane production in anaerobic digestion process. The potential promotion effects of iron oxides nanoparticles( IONPs),especially magnetite nanoparticles on anaerobic digestion are also mentioned. Fe plays important role in transporting electron,stimulating bacterial growth and increasing hydrogen and methane production rate by promoting enzyme activity. Adding Fe with different morphologies and valence states in anaerobic digestion to increase biogas( hydrogen and methane) production and enhance organic matter degradation simultaneously,which has attracted many scientists' attention in recent years. Rapid progress in this area has been made over the last few years,since Fe is essential to the fermentative hydrogen and methane production,while few is known about how Fe affects the fermentative biogas production. This review is significant to maintain the stable operation of the biogas project.

Influence of Polycarboxylate Superplasticizer on Rheological Behavior in Cement Paste

Molecular structures of polycarboxylate（PCE） superplasticizer significantly affect the rheological properties of cement paste. Consequently, we employed self-synthesized PCE copolymers with different carboxylic densities to investigate their influence on the rheological behavior of cement paste. Three typical rheological models were applied to analyze the rheological properties, including Power-law model, Bingham model as well as Herschel-Buikley model. In addition, the thixotropical performances of cement paste in the presence of PCE with different carboxylic densities were investigated. The results show that the carboxylic density of PCE greatly influences the dispersing performance of PCE superplasticizers. As carboxylic density increases, the dispersing capability of PCE improves, and P（PEG1-AA6） possesses the strongest dispersing capability, the initial fluidity and 1 h fluidity of cement paste are both the highest, and cement paste has the lowest viscosity and the smallest hysteresis loop.

Modified origin-based algorithm for traffic equilibrium assignment problems

Key tactics of origin-based user equilibrium (OUE) algorithm was studied,which involved the algorithm procedure and several implementation issues.To speed up the convergence,update policies of flows,costs and bushes were proposed.The methods of step-size searching and bush construction are proved to be practical.The modified OUE algorithm procedure was also optimized to take the advantage of multi-thread process.Convergence performances were compared with those of other algorithms by different sizes of urban transportation networks.The result shows this modified OUE algorithm is more efficient and consumes less time to achieve the reasonable relative gap in practical applications.

Heat transfer characteristics of molten plastics in a vertical falling film reactor

The heat transfer efficiency during the pyrolysis process is a key factor to be considered in the design of pyrolysis reactors. In this study, the average apparent heat transfer characteristics of molten plastic pyrolysis in a vertical falling film reactor were explored by experiments and numerical simulation and the apparent heat transfer coefficients were determined. In addition, the temperature distribution and the thickness of the liquid film in the reactor were predicted and the influences of pyrolysis temperatures on the average apparent heat transfer coefficients were discussed.

Full-scale experiment for segmental linings of deep-buried shield tunnels bearing high inner water pressure:Comparison of mechanical behaviors of continuous-and stagger-jointed structures

Full-scale loading tests were performed on shield segmental linings bearing a high earth pressure and high inner water pressure,focus-ing on the effects of the inner water load and assembly manner on the mechanical properties of the segmental linings.The test results indicate that the deep-buried segmental linings without inner pressure have a high safety reserve.After the action of high inner water pressure,the lining deformation will increase with the reduction of the safety reserve,caused by the significant decrease in the axial force in the linings.Because the bending moment at the segmental joints is transferred to the segment sections in the adjacent ling rings,the convergence deformation,openings of segmental joints,and bolt strains are smaller for the stagger-jointed lining than those for the continuous-jointed lining;however,dislocations appear in the circumferential joints owing to the stagger-jointed assembly.Although it significantly improves the mechanical performance of the segmental lining,stagger-jointed assembly results in compromising the water-proofing safety of circumferential joints.The stagger-jointed assembly manner can be considered to improve the service performance of shield tunnels bearing high inner water pressure on the premise that circumferential joint waterproofing is satisfied.

Bamboo Winding Composite Utility Tunnels:a case study on mechanical behavior with WSN monitoring and numerical simulation

竹缠绕复合管(BWCP)具有力学性能优良、成本低、低碳环保、隔热、安装方便等优点。目前,竹缠绕复合管被广泛应用于城市给排水、电缆保护、农田灌溉等领域。竹缠绕复合材料在综合管廊领域具有良好的应用前景。然而,考虑到综合管廊的尺寸要远大于一般管道,竹缠绕复合管廊(BCUT)的广泛应用仍然是一个挑战。本文采用实时监测和数值模拟两种方法对山西大同的竹缠绕复合管廊受力性能进行了研究。采用WSN对其进行监测,获得了管廊收敛和应变实时监测数据。监测数据表明水平收敛能够满足相关技术规范的要求。利用有限元软件建立了管廊的三维数值模型,分析土体参数对管廊变形和应变的影响,并将数值模拟结果与实测数据进行比较分析。研究表明,土体参数K_(0)和k_(sh)对管廊变形、应力和应变影响非常显著。竹缠绕复合管廊建议在地质条件较好的地区使用。

Numerical investigation and optimal design of fiber Bragg grating based wind pressure sensor

A wind pressure sensor based on fiber Bragg grating （FBG） for engineering structure was investigated in this paper. We established a transaction model of wind pressure to strain and proposed a method of temperature compensation. By finite element analysis, the basic parameters of the sensor were optimized with the aim of maximum strain under the basic wind pressure proposed in relative design code in China taking geometrical non-linearity into consideration. The result shows that the wind pressure sensor we proposed is well performed and have good sensing properties, which means it is a technically feasible solution.

Microbial fuel cell with high content solid wastes as substrates： a review

With the increasing concern about the serious global energy crisis and high energy consumption during high content solid wastes （HCSWs） treatment, microbial fuel cell （MFC） has been recognized as a promising resource utilization approach for HCSW stabilization with simultaneous electrical energy recovery. In contrast to the conventional HCSW stabilization processes, MFC has its unique advantages such as direct bio-energy conversion in a single step and mild reaction conditions （viz., ambient temperature, normal pressure, and neutral pH）. This review mainly introduces some important aspects of electricity generation from HCSW and its stabilization in MFC, focusing on： （1） MFCs with different fundamentals and configurations designed and constructed to produce electricity from HCSW; （2） performance of wastes degradation and electricity generation; （3） prospect and deficiency posed by MFCs with HCSWas substrates. To date, the major drawback of MFCs fueled by HCSW is the lower power output than those using simple substrates. HCSW hydrolysis and decomposition would be a major tool to improve the performance of MFCs. The optimization of parameters is needed to push the progress of MFCs with HCSW as fuel.

How to Calculate Stormwater Management and Storage Capacity for Urban Green Space: Multidisciplinary Methods Used in Shanghai City

In order to relieve urban environmental problems due to stormwater runoff,approaches involving the planning of green space for sponge city construction were previously proposed.In this study,water retention characteristics of 168 green spaces are surveyed to develop estimates of stormwater retention in Shanghai City’s center,suburbs and outskirts.Multidisciplinary methods of community investigation,soil tests,artificial rainfall simulation experiments,and simulations in Autodesk storm and sanitary analysis(SSA)and storm water management model(SWMM)are used.The factors affecting the capacity of stormwater management are identified and used to calculate storage estimates.The relationships among rainfall interception capacity(RIC),runoff,soil water storage properties,and vegetative cover are analyzed,which can provide the theoretical foundation for the assessment of the water-holding capacity in urban green spaces.A criterion for the selection of low impact development(LID)techniques for the Shanghai area is developed on the basis of the data from this study.

Co-present Pb(Ⅱ)accelerates the oxidation of organic contaminants by permanganate:Role of Pb(Ⅲ)

The permanganate(Mn(VII))oxidation has emerged as a promising technology for the remediation and treatment of the groundwater and surface water contaminated with the organic compounds.Nonetheless,only a few studies have been conducted to explore the role of the heavy metals(especially the redox-active ones)during the Mn(VII)oxidation process.In this study,taking Pb(II)as an example,its influence on the Mn(VII)decontamination performance has been extensively investigated.It was found that,with the presence of Pb(II),Mn(VII)could degrade diclofenac(DCF),2,4-dichlorophenol,and aniline more effectively than without.For instance,over a wide pH range of 4.5–8.0,the dosing of 10μmol/L Pb(II)accelerated the DCF removal rate from 0.006–0.25 min–1 to 0.05–0.46 min–1 with a promotion factor of 1.9–9.4.Although the UV-vis spectroscopic and high resolution transmission electron microscopy analyses suggested that Mn(VII)could react with Pb(II)to produce Mn(IV)and Pb(IV)at pH 6.0–8.0,further experiments revealed that Pb(II)did not exert its enhancing effect through promoting the generation of MnO_(2),as the reactivity of MnO_(2)was poor under the employed pH range.At pH below 5.0,it was interesting to find that,a negligible amount of MnO_(2)was formed in the Mn(VII)/Pb(II)system in the absence of contaminants,while once MnO_(2)was generated in the presence of contaminants,it could catalyze the Pb(II)oxidation to Pb(IV)by Mn(VII).Collectively,by highlighting the conversion process of Pb(II)to Pb(IV)by either Mn(VII)or MnO_(2),the reactive Pb(III)intermediates were proposed to account for the Pb(II)enhancement effect.

Effect of ventilation on thermal and humidity environment of the underground utility tunnel in the plum rain season in southern China:Field measurement and CFD simulation

The underground utility tunnel(UUT)is one of the typical urban underground structures,which usually requires mechanical ventilation systems for forced ventilation.In addition to the ventilation scheme for accident scenarios,the normal operating ventilation scheme deserves equal attention as it has a great impact on the air quality as well as the thermal and humidity environment inside the UUT.In this study,a UUT located in southern China is taken as the research object,and the effect of ventilation on its internal thermal and humidity distribution is explored with a combined use of field measurements and numerical simulations.The results of field measurements show that the average temperature inside the closed UUT is 20.5℃and the average humidity ratio is 14.1 g/kgdry;both are lower than those of the external environment.In the plum rain season,if the tunnel is ventilated without any treatment of the external airflows,surface condensation tends to occur near the air inlet while the region with high relative humidity would be distributed on both sides far from the air inlet.The study also discusses the effect of different temperatures and humidity ratios of the inflow air on the humidity inside the UUT,and on this basis,the humidity control strategy for UUT in the plum rain season is proposed.

The acceleration degradation processes of different aged refuses with the forced aeration for landfill reclamation

Forced aeration is one of the promising ways to accelerate landfill reclamation,and understanding the relation between aeration rates and waste properties is the prerequisite to implementing forced aeration under the target of energy saving and carbon reduction.In this work,landfill reclamation processes with forced aeration were simulated using aged refuses(ARs)of 1,4,7,10,and 13 disposal years,and the potential of field application was also investigated based on a field project,to identify the degradation rate of organic components,the O_(2)consumption efficiency and their correlations to microbes.It was found that the removal rate of organic matter declined from 20.3%(AR_(1))to 12.6%(AR_(13)),and that biodegradable matter(BDM)decreased from 5.2%to 2.4%at the set aeration rate of 0.12 L O_(2)/kg waste(Dry Matter,DM)/day.A linear relationship between the degradation rate constant(K)of BDM and disposal age(x)was established:K=−0.0002193x+0.0091(R^(2)=0.854),suggesting that BDM might be a suitable indicator to reflect the stabilization of ARs.The cellulose/lignin ratio decrease rate for AR1(18.3%)was much higher than that for AR13(3.1%),while the corresponding humic-acid/fulvic-acid ratio increased from 1.44 to 2.16.The dominant bacteria shifted from Corynebacterium(9.2%),Acinetobacter(6.6%),and Fermentimonas(6.5%),genes related to the decompose of biodegradable organics,to Stenotrophomonas(10.2%)and Clostridiales(3.7%),which were associated with humification.The aeration efficiencies of lab-scale tests were in the range of 5.4–11.8 g BDM/L O_(2)for ARs with disposal ages of 1–13 years,and in situ landfill reclamation,ARs with disposal ages of 10–18 years were around 1.9–8.8 g BDM/L O_(2),as the disposal age decreased.The increased discrepancy was observed in ARs at the lab-scale and field scale,indicating that the forced aeration rate should be adjusted based on ARs and the unit compartment combined,to reduce the operation cost.