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Abstract The mathematical model of heating substation, which is an important part of district heating system, is presented in this paper. The main components of district heating substation system, from the automatic control perspective, that are observed in this paper are heat exchanger and three-way valve. Presented mathematical model is developed so it could operate in real-time, since the crucial aspect of development, deployment and testing of new control techniques and optimization algorithms is their accurate validation on the real system. However, the accessibility to a real system is often not possible. Corresponding to this, an alternative is the existence of the correct mathematical model of a process, with the ability to operate in real-time. First, the presented mathematical model of district heating substation is decomposed to the simpler models of its main elements, in order to provide the analysis of the various parameters on the model performance through numerical simulation. Second, a real-time model is developed in LabVIEW software package and deployed on the embedded controller with a real-time processor as a three-layer application which enables data acquisition and communication with a programmable controller. [ABSTRACT FROM AUTHOR]

Abstract Water pumping systems are widely used in industrial and civil applications. During their operational life, they consume energy and materials (mainly for installation and replacement of components). The aim of this paper is to optimize the pump operations in order to save energy and enlarge the operational life of the pumps and their components. This paper addresses the multi-period (e.g. 24-hours time horizon) optimization of pumping systems. To this end, we have developed a simulation-based optimization approach including novel relevant technical features of a generic but realistic pumping system, namely cavitation and overflow. The proposed multi-period optimization differs further from the classic static optimization (i.e. at the design stage), proposing a new dynamic approach in which pump activation is steered dynamically for an optimal management of the variability of water inflow. Furthermore, the problem includes constraints on the number of pump activations allowed to reduce material strain. The performances of different meta-heuristic optimization algorithms (e.g. genetic algorithm, simulated annealing and particle swarm optimization) for solving the problem are compared. The numerical results show that energy savings are possible with the dynamic approach and that particle swarm optimization and simulated annealing algorithms provide the most suitable solutions for this problem. Highlights • Three algorithms are compared to minimize energy pump consumption. • The pump model includes energy, cavitation, overow and activation frequency. • Static and dynamic optimizations are investigated. • The dynamic optimization can reduce the energy consumption by 6.5%. [ABSTRACT FROM AUTHOR]

Abstract The ventilation effect in different places in the teaching building is different. The aim of this paper is to study the relative ventilation relationship of the rooms in "line" type middle school teaching building. Taking Xiamen in the subtropical region as a typical city, a number of parameters such as the inside and outside corridors, different room sizes and different ventilation angles were set as variables, using the CFD simulation method. Combined and separated effects of the defined parameters on natural ventilation performance are evaluated using the ratio of air-age area as criteria. The result shows that the "line" type teaching building with outside corridor ventilation is 35.55% better than the inside corridor. In addition, the ventilation in large room is 30.84% better than that in small rooms. In 0°–35° wind direction, the closer the room to the incident wind the better in ventilation, but in a certain angle range of 59°–90°, the room farther away from the incident wind, the better in ventilation. The best wind angle of "line" teaching building ventilation is 305°–55°. The research results in this paper can help architects to design buildings more scientifically and reasonably. Highlights • "Line" type teaching building should adopt outside corridor form, it is conducive to ventilation in subtropical area. • The outside corridor ventilation effect is 35.55% better than the inside corridor. • Large room is suitable for laboratory and small room is suitable for temporary lounge cause ventilation feature. • The ventilation effect of the classrooms is related to the wind direction and classroom positions. [ABSTRACT FROM AUTHOR]

The performance of a manufacturing system is measured by factors such as its productivity and energy efficiency. Current systems lack the required indices to measure its efficiency and highlight the areas of inefficiency in the system. The paper is aimed at improving the overall performance of manufacturing system by suggesting methods for integrated improvement in above two factors. This paper establishes performance indices for measuring energy efficiency and productivity of the system, which uses easily available sensor data from the production line. The energy structure and effects of downtime events on the production line has been analyzed to develop energy and productivity performance indicators. The indices are utilized to identify the machines which is most power inefficient and results in maximum production loss of the system. These indicators are utilized to illustrate our method for improving productivity and concepts of downtime-bottleneck and power-bottleneck. The methods proposed are verified by simulation studies. [ABSTRACT FROM AUTHOR]

The zinc powder replacement method for Co removal is characterized by several challenges, such as poor mass transfer and agglomeration. To solve this problem, the ultrasonically enhanced zinc powder replacement method was developed and used to remove Co from the sulfate solution, and a 95.02% removal rate of Co was achieved under the optimized condition. Compared with conventional conditions, the removal rate increased by 24.5%. The behavior and mechanism of zinc powder replacing Co were comprehensively analyzed through electrochemistry and COMSOL Multiphysics. Chronoamperometry curves showed that after the introduction of ultrasound, the reaction current increased by approximately two times compared with the conventional condition. The cyclic voltammetry (CV) curves showed that the reduction potential of Co positively shifted, accompanied by an increase in peak current. The electrochemical impedance spectroscopy (EIS) tests showed that the nuclear transmission resistance decreased by approximately 1.6 times compared with conventional conditions. In addition, the COMSOL simulation revealed that, after the system was subjected to ultrasonic conditions, the temperature, flow rate, and sound pressure physical field increased, which accelerated the heat and mass transfer process in the solution. The removal behavior of the system was studied using scanning electron microscopy and X-ray diffraction. Ultrasonic waves decomposed the insoluble substances on the surface of zinc powder, refined the particles, and improved the removal rate of Co. This provides new insights into the ultrasound-enhanced reaction. In this paper, we introduce an innovative approach by ultrasonic enhanced zinc powder for the replacement removal of cobalt, achieving high-efficiency cobalt elimination. Additionally, the electrochemical kinetics of the zinc powder replacement process is comprehensively investigated. Theoretical validation of ultrasound-enhanced heat and mass transfer processes within the solution was achieved through numerical simulations conducted using COMSOL software. [Display omitted] • Ultrasound was used to improve the efficiency of Co removal from zinc sulfate solution. • The removal rate was increased by 24.65% compared with convention. • The introduction of ultrasound increased the mass transfer in the solution. • Ultrasound decomposed the insoluble substance on the surface of the zinc powder. [ABSTRACT FROM AUTHOR]

A carbon reduction labelling scheme is an effective policy tool for motivating enterprises or organizations to reduce their life-cycle-based carbon emissions to benefit the environment. This paper uses system dynamics to model enterprises' compliance with a combined government policy instrument for a carbon reduction labelling scheme, that is, government subsidies and economic sanctions. A case study of paper enterprises in China is provided to demonstrate the application of the proposed model in which two optional technological plans to reduce the enterprises' carbon emissions are examined. The technological plans are categorized as a low-cost and high-cost plan. The simulation results show that both the technological plans are vulnerable to the combined policy making, and the high-cost plan shows superior environmental performance for carbon emissions reduction. However, the enterprises are more inclined to choose the low-cost plan because of superior economic performance. The study offers insights to help enterprises select optimal actions on carbon emissions reduction and to inform government of possible sustainable policy design to promote low-carbon development. The model limitations are discussed as a basis for further improvements in low-carbon development. [ABSTRACT FROM AUTHOR]

System Dynamics can be a powerful tool for understanding dynamics, especially feedback behaviours, in many social-ecological systems where sustainable pathways are sought. Along with quantitative simulations and optimization packages, System Dynamics offers qualitative tools (e.g. system archetypes, Causal Loop Diagrams, and Stock and Flow Diagrams) for further enhancing understanding. Like all methods, System Dynamics can be applied effectively and successfully for specific objectives in specific contexts by some analysts and modellers, but can also be used poorly and potentially unethically by others. This paper investigates the potential of System Dynamics to support Sustainability and the role played by modellers, including their practices and assumptions, in developing this potential. This is achieved by reviewing the application of System Dynamics within the context of the sustainability literature and how there are multiple levels of boundary judgements to be made by System Dynamics modellers, their commissioners and stakeholders: specifically around the sustainability principles that provide the criteria by which policy options from the modelling are evaluated; definitions of problem scope; and around the extent of dynamic processes explicitly considered in both the qualitative and quantitative System Dynamics thinking and modelling practice. To illustrate how boundary judgements matter for sustainability modelling, we draw on three examples, and discuss the potential risks and challenges these raise. The paper also discusses how and why System Dynamics needs to be used by analysts in a more complete manner (i.e. engaging qualitative, quantitative, and participatory approaches) to ensure that in any given applied case, the models, and the judgements underpinning their development, are effectively embedded in societal and political contexts that allow their use for supporting sustainability. [ABSTRACT FROM AUTHOR]

Carbon dioxide geological sequestration simultaneously combined with water production from deep saline aquifer can effectively address the challenge faced by modern energy systems of reducing carbon dioxide emissions and water intensity while providing reliable, affordable, and secure energy. However, little attention has been paid to date in the literature on determining the carbon dioxide injection strategy for achieving both the optimal water production and the optimal carbon dioxide storage capacity while maintaining operational safety. This paper first establishes three injection–extraction scenarios based on the typical geological parameters of the Junggar Basin in China to analyze the effect of carbon dioxide injection on water extraction and the effect of water extraction on the carbon dioxide storage. The three injection scenarios considered are sole carbon dioxide injection, sole water production and combined carbon dioxide enhanced water recovery. The carbon dioxide enhanced water recovery scenario is then optimized using a genetic algorithm to determine the trade-off between the maximum possible water recovery and the safe carbon dioxide storage for both the constant mass injection and the variable time-dependent mass injection (for achieving constant pressure injection). The influence of number of pumping wells is also analyzed. It can be concluded from this work that the carbon dioxide enhanced water recovery technology can effectively manage the pressure perturbation caused by the carbon dioxide injection as well as the water production while significantly enhancing the carbon dioxide storage capacity, security and water production efficiency. Injection strategy is essential to the efficiency of carbon dioxide enhanced water recovery; the genetic algorithm based optimizer combined with the well-known multi-phase flow solver TOUGH2, designated as GA-TOUGH2 is used for the optimization of injection scenarios. It is found that in the allowable range of pressure perturbations, a higher carbon dioxide injection rate is more beneficial for carbon dioxide storage as well as for water production. Constant pressure injection operation is superior to the constant rate injection and leads to higher carbon dioxide storage capacity and stability, and water production efficiency. Adding pumping wells can somewhat enhance the carbon dioxide storage capacity especially for the constant pressure injection operation compared to the constant rate injection operation as well as the water production efficiency; however, the enhancement in water production is very small compared to the single well and cannot be regarded as economical considering the additional capital cost of well drilling. This paper addresses the method of combined numerical simulation and optimization for carbon dioxide enhanced water recovery from saline aquifers that can be employed in the implementation of enhanced water recovery at industrial scale. [ABSTRACT FROM AUTHOR]

A fundamental problem in the management of energy usage is the inability to clearly predict any possible energy saving opportunities. The cost of both under or overestimating potential returns on investment can be prohibitive to a decision maker. In recent years the simulation of energy usage using existing manufacturing simulation tools has increased in popularity among researchers, but it is decision makers who need to see the benefits of this discipline. This paper proposes an interactive manufacturing energy management toolkit which makes use of existing productivity simulation models for the prediction of energy usage. An interactive Microsoft ® Excel ® based toolkit is developed to control Lanner's WITNESS ® discrete-event simulation software using Microsoft ® Visual Basic ® for Applications. The toolkit has the ability to predict potential areas where energy saving opportunities can be made within a complex manufacturing line, and is accessible from management presentations and proposals. The interactivity of the toolkit provides an environment which facilitates efficient hypothesis testing. The paper includes an industrial case study where the approach was used to quantify theoretical savings from certain energy usage reduction scenarios within a complex automotive engine manufacturing line. [ABSTRACT FROM AUTHOR]

Different types of technical barriers in the operation of an eco-industrial system have been identified theoretically as a result of the exploration and implementation of ecological industrial parks since the 1990s. However, the vulnerability of these systems is amplified by inadequate management. In this paper, we describe the indicators of stability in an eco-industrial system based on complex network theory to build a cascading failure model for the system. A case from the Qinghai Salt Lake Ecological Industrial Park is introduced to construct the network topological structure and simulate the network cascading failure transmission. We discuss how two types of node enterprises impact the stability of the eco-industrial system. The results show how various node enterprises with different mechanisms affect the systematic stability of the eco-industrial network and how the removal of core node enterprises can lead to greater damage to the network. Managers of eco-industrial systems should focus on structural core enterprises and core industrial chains. In this paper, the managerial implications can provide reliable guidance for stable operations in an eco-industrial system. [ABSTRACT FROM AUTHOR]

Dust deposition on the surface of photovoltaic (PV) modules leads to a decrease in photoelectric conversion efficiency and output power. To identify the dust deposition factors and laws, scholars have conducted numerous field experiments or numerical simulations. However, few scholars have studied the mechanism of dust deposition with three-dimensional (3D) simulation models. The parameters affecting dust deposition vary in different geographical regions, which limits the applicability of research findings on dust deposition to specific geographical areas. To address these issues, this paper first proposes dust adsorption conditions on the surface of PV modules. Based on the main dust deposition factors, a 3D simulation model for dust deposition is established, and the accuracy and effectiveness of the adsorption conditions and simulation model are verified. Then, with a combined approach of orthogonal experiments and 3D simulation analysis, the main dust deposition factors and laws are analyzed. Finally, regional clustering is conducted by dust deposition factors, and the simulation results are applied to the regional optimization of installation parameters. The case study results show that the PV modules have a maximum power generation of 231.91 kWh with an optimal installation angle of 17° and an installation height of 0.5 m in the I category region. [Display omitted] • The dust adsorption conditions based on the incident normal critical velocity as the judgment criterion were established. • A combined approach of orthogonal experiments and 3D simulation analysis is proposed. • The most consistent geographical categories of dust deposition influencing factors were obtained by cluster analysis. • A partition optimization design of installation parameters was performed to improve power generation. [ABSTRACT FROM AUTHOR]

Abstract Durability of products and lifetime extension through improvements in product design, repair, reuse and refurbishment are integral components of the circular economy concept. Extended service lifetimes reduce the demand for new resource intensive products and hence contribute to an increase in resource efficiency and resource conservation. However, the use of a consumer product does not only depend on its functioning. Particularly consumer electronics such as smartphones are often only used for comparatively short periods of time before they are replaced by new devices. Even though these used electronics may still have significant value and could be resold as secondhand products, they often remain in households (compartments, shelves, cellars) for long periods of time. When analyzing the effects of technical improvements for lifetime extensions of consumer products, these storage times, which are also referred to as hibernation, need to be taken into account. Hibernation counteracts efforts towards increasing the service lifetimes of consumer electronics and should therefore more strongly be addressed in the discussion about lifetime extension and higher durability. In this paper, we present a dynamic cascade stock and flow model to simulate different use and storage phases of consumer electronics in Europe. This model enables a detailed analysis of modifications in service lifetimes and storage phases. The simulation results emphasize the significant proportion of unused but functioning electronic devices when regarding overall product stocks in society. Based on the simulation results, we show that particularly for small consumer electronics such as smartphones, the systematic implementation of a cascade use system avoiding storage phases could significantly reduce total product demand and the associated resource use. Subsequently, we discuss potential measures that could lead to a reduction of storage time of unused consumer electronics in typical households. [ABSTRACT FROM AUTHOR]

Abstract A river basin usually provides water for multiagent. Imperfect coordination mechanisms among these agents, however, usually lead to serious water shortage, pollution, and ecological degradation. Therefore, it is vital to conduct research on allocating different kinds of water resources among multiagent including the water quantity agent, water quality agent and environment agent within a river basin. This paper proposes an optimization-simulation method that takes into consideration engineering measures, including water transfer projects, reservoirs, canal heads, and pump stations; multi-water resources such as local surface water, transferred water, groundwater, and reused sewage; and multiagent for remitting serious water problems. In the proposed optimization-simulation method, the groundwater and reused sewage are first allocated according to the water resources allocation simulation module (Module 1). Then, local surface and transferred water are allocated based on the water resources allocation optimization module (Module 2), which comprises water quantity, water quality and environment agents' objectives based on synergism. Finally, the instream water quality is simulated according to the water quality simulation module (Module 3). Results show that, compared to the current situation, the water quantity and environment agent guarantee rates can satisfy the design requirements in the planning year of 2020. The regulated instream water quality is also improved; although, it still remains relatively poor. Water quality in the downstream is worse than that in the upstream. In addition, the water quality shows a positive correlation with the instream streamflow. These results certify the proposed optimization-simulation method can provide support for efficacious multiagent water resources allocation. Highlights • A coupled quantity-quality-environment water allocation model is constructed. • Multi-water resources, many types of engineering projects and multiagent are considered. • Multi-water resources cover local surface, transferred water, groundwater, and reused sewage. • Water transfer projects, reservoirs, canal heads, and pump stations are selected projects. • Coupled model is solved by an optimization-simulation method. [ABSTRACT FROM AUTHOR]

Abstract The vehicular emission modelling software COPERT is extensively used in generating emission levels for National Emissions Inventory in Europe and in some other countries internationally. This paper aims to study the uncertainties associated with emission estimates generated from COPERT(v5.1) outputs through sensitivity analysis of the model input parameters. The input parameters considered in this study are temperature, speed, relative humidity, trip length, and driving style (mileage share). Many of these parameters are not directly measured or country-wide average values are investigated in this study. The uncertainties of the emission estimates were obtained through varying the parameter values, within realistic limits, either individually or considering factor interactions by varying two or more parameters simultaneously. The uncertainties of the emission estimates of certain pollutants (CO, VOC and NMVOC) can be significant from −58% to +76%. Some gases, such as CO 2 show almost no sensitivity to input parameter variations. The results indicate that the COPERT outputs are most sensitive to variations in trip length and speed, both of which are not directly measured. Considering the percentage of urban driving share has a huge effect on the national emission estimates, inventories were separately prepared for the Greater Dublin Area (GDA), the largest urban area of Ireland with highest population and vehicle densities. GDA has 48% and 50.37% shares of CO 2 and NOx emissions respectively, compared to the national levels. The consequence of over- or underestimation of emission inventories for Ireland was calculated to be approximately +/− €45million. Considering the major implications of NEI for climate change and other related impacts it is crucial to report the pollutant emission levels appropriately stating uncertainty levels. The findings of this study provide national experts with a methodology to estimate uncertainties of COPERT outputs and to identify the key sources of these uncertainties where policy and emission reduction strategies should be targeted. Graphical abstract Image 100836 Highlights • Vehicular emission levels modelled using COPERT varies significantly based on assumptions. • Sensitivity modelling of COPERT input parameters, values of which are not widely measured. • Individual & interactive effects of temperature, speed, driving style etc. on emission variations. • Uncertainties of CO, VOC, NMVOC, N 2 O levels are greater than uncertainties of CO 2 , NOx, & PM levels. • Damage costs of pollutants under/overestimated by approximately 43.9 mil€. [ABSTRACT FROM AUTHOR]

Abstract Concrete is one of the most widely used construction materials in the world. However, its sustainability is currently being challenged by the depletion of natural resources necessary to produce it (mainly due to the mining of aggregates) and the use of landfill space for its final disposition after service use. At the same time, the need for faster construction has encouraged the utilization of precast concrete structures, including pre-stressed elements. Recycled concrete aggregates could make the fabrication of concrete more sustainable; several studies demonstrate the technical feasibility of recycled concrete aggregates in Portland cement concrete for structural use. However, the sustainability of recycled concrete aggregates needs more reliable methodologies to assess it. This paper presents a stochastic simulation model of the precast fabrication process that considers obtaining materials, materials transportation, and precast elements production to evaluate the use of water, generation of CO 2 emissions, and costs incurred when using natural coarse aggregates versus recycled concrete coarse aggregates from several sources. The model is based on data from companies in the United States, Canada, and Chile. The results show that replacing natural coarse aggregates with recycled concrete coarse aggregates reduces CO 2 emissions and costs for the production of precast concrete elements, compared with the conventional system. However, water consumption is increased when recycled concrete coarse aggregates is used. Therefore, this research shows that the use of recycled concrete coarse aggregates for precast plants can be beneficial in terms of CO 2 emissions and cost in contexts where water is not a scarce resource. Graphical abstract Image 1 Highlights • Recycled Concrete Aggregates in precast elements reduce CO 2 emissions. • The cost of precast elements is reduced using Recycled Concrete Aggregates. • Recycled Concrete Aggregates in precast elements increase fresh water consumption. [ABSTRACT FROM AUTHOR]

Abstract Considering the game among enterprises, this paper studies low-carbon diffusion problem from the perspective of network characteristics and consumers' environmental awareness. Under the scenario of heterogeneous environmental awareness, the low-carbon diffusion model based on evolutionary game theory and complex network theory is established to describe the game of enterprises' low-carbon strategy adoption in the network and the strategy learning among network neighbors. Simulation analysis in complex networks reveals the roles of network characteristics such as average degree, degree distribution and consumers' environmental awareness played in low-carbon diffusion. The results show that increasing the connections among enterprises in the industry can help the spread of low-carbon strategies. However, the diffusion potential of the network is largely exploited when the average degree exceeds 6, and the low-carbon strategies spread slowly afterwards. A certain percentage of green consumers drives this certain percentage of enterprises to implement low-carbon strategies approximately in equilibrium which indicates that the low-carbon diffusion rate can reach 100% when all consumers become green consumers who are willing and able to pay for low-carbon premium. White customers contribute to the spread of low-carbon strategies, but the promotion effect is not as good as green customers. The small-world (SW) network is more efficiently than the scale-free (SF) network in low-carbon diffusion when consumers' environmental awareness is low. However, when the consumers' environmental awareness is higher than a certain value, the SF network has a higher diffusion rate in equilibrium than the SW network. Highlights • The evolutionary game model on low-carbon diffusion in complex network context is constructed. • The characteristics of complex network such as average degree and degree distribution affect low-carbon diffusion. • Green customers are the determinants of low-carbon diffusion and white consumers are the icing on the cake. • The priority of low-carbon diffusion in SW network and SF network relates to customers' environmental awareness. [ABSTRACT FROM AUTHOR]

Abstract Improving thermal insulation of buildings envelopes can reduce their energy consumption and related CO 2 emissions considerably. Searching for new and innovative insulation materials is therefore a key challenge. This paper presents an experimental study to show the effect of adding spent coffee grounds (SCGs) on thermal properties of plaster composite. The obtained results using the box method show a significant decrease of thermal conductivity along with an increase of the coffee ground content, indicating the possible usage of the resulting material as efficient insulation in buildings. It is found that the thermal conductivity of the resulting building material can be decreased from 0.5 to 0.31 W/m.K by adding 6 wt% of CGs to the initial material. To illustrate energetically and environmentally the benefit of using the proposed material, annual simulations were carried out for a typical Moroccan house located in Marrakech. The results indicated that up to 20% of the cooling and heating loads of the building can be reduced if the proposed material substitutes the conventional one. From an environmental point of view, the utilization of the proposed material can reduce up to 1500 kg CO 2 , annually for the studied case. [ABSTRACT FROM AUTHOR]

Abstract Electricity consumption accounts for a significant portion of final energy consumption in countries worldwide and has a close relationship with economic growth. This paper explores the factors influencing electricity consumption in China during 1990–2016 using index decomposition analysis, and analyses the decoupling status between economic growth and electricity consumption, in addition to the influencing factors. These analyses are conducted at both national and sectoral levels. The results reveal that: (1) The economic activity effect was the main driving force increasing total electricity consumption in China, while the energy intensity effect hindered it. (2) Both diversity and aggregation existed at the sector level. The power generation, chemicals, and non-ferrous sectors were the top three contributors to increased electricity consumption. (3) The change of electricity consumption caused by GDP growth in China showed three decoupling states during 1990–2016: expansive negative decoupling, expansive coupling and weak decoupling. In particular, the energy intensity effect stimulated the occurrence of decoupling. (4) Industrial sectors played a significant role in decoupling in China, while service sectoral electricity consumption showed expansive coupling with its sectoral GDP in recent years. Graphical abstract Image Highlights • Decomposition and decoupling methods were used to analyse China's electricity consumption. • Analyses were conducted at both national and sectoral levels. • Influencing factors in China's different FYP periods and sectors were identified. • Energy intensity effect played a positive role in decoupling. • Decoupling relationship at the sectoral level was discussed. [ABSTRACT FROM AUTHOR]

Abstract The sustainability of the water-energy-food (WEF) nexus is a significant challenge faced by developing countries, especially China. Evaluating the sustainability status of China's water-energy-food, and improving its sustainable use, may provide good physical conditions to support China's future development. This paper applied the Pressure, State, and Response (PSR) model to select evaluation indexes. A combination weighting method was used to combine two objective weighting methods to determine index weights. The study constructed the classical field, the limited field, and the matter-element to be evaluated. This allowed the establishment of an improved matter-element extension model to evaluate the sustainability of the water-energy-food nexus; the model was then used to quantitatively evaluate the sustainability of China's water-energy-food nexus. The simulation results indicated that in 2005, the sustainability of China's water-energy-food was at a relatively low efficiency rank. By 2015, the sustainability of China's water-energy-food had reached a general efficiency rank. The results suggested that the sustainability of China's water-energy-food system significantly improved between 2005 and 2015; however, the improved sustainability remained at a general status (The general status means that the sustainability of water-energy-food nexus in China can meet the basic development needs, but it is far from the optimal state and needs further adjustment and improvement). Thus, China should improve its current utilization patterns for the three resources and consider them as a whole. This would help realize synergistic resource use and enhance their sustainability. Highlights • The sustainability of WEF nexus is a severe challenge faced by developing country. • An improved matter-element extension model to evaluate sustainability of WEF nexus. • The sustainability of China's WEF system significantly improved from 2005 to 2015. • China should improve its utilization patterns for the WEF and consider it as whole. [ABSTRACT FROM AUTHOR]

Building life cycle assessment (LCA) aims at guiding decision towards more sustainable alternatives of a building project. But, in order to successfully reduce the high environmental impacts of the building sector, the results of building LCA have to be robust. Sensitivity analysis (SA) helps at investigating the sources of uncertainty and variability in a model and assessing the results' robustness. Choosing an adapted SA method remains difficult: using the more precise SA methods would require a too large calculation time, particularly for an application in early design phase. In this paper, the most influential factors of building LCA tools, linked with energy simulation tools, were investigated using screening and global SA methods that are compatible with the building LCA fields. The relative influence of the uncertain factors served as a metric to compare more precisely the results given by this large panel of methods. The results show that despite their different precision vs computational cost compromises, all the methods identified the same set of influential factors. In the studied case of a passive single family house, they consisted in the building lifetime, the electricity production mix and factors affecting the energy consumption. However, the relative influence of the factors differed. Two new method adaptations were investigated in order to obtain precise results in a reasonable simulation time. The adaptation of the Plackett and Burman (PB) screening performed well compared to the reference method (Sobol indices), as the same set of influential factors was always identified in a calculation time divided by almost 30. [ABSTRACT FROM AUTHOR]

China has been experiencing a rapid urbanization process. Various relevant policies and strategies have been implemented for sustainable urbanization. For a better understanding of sustainable urbanization, many research efforts have been made on urban sustainability assessment. The traditional indicator index is normally used to evaluate the urban sustainability performance. However, the urban development is a complex system, and the existing methods cannot reflect the systemic interactions among variables. Therefore, this paper aims to develop a system dynamics model for simulating urban sustainability performance. The system dynamics model comprises four sub-systems, namely, the economic sector, social sector, environment sector and resource sector. Then, the system dynamics model is used to simulate the sustainability performance of the city, Beijing, with three scenarios. The results indicate that the system dynamics modelling is a useful tool for simulating urban sustainability performance and can help policy makers formulate relevant strategies for a better sustainable development of cities. [ABSTRACT FROM AUTHOR]

The vertically integrated operation system of natural gas transmission has led to lagging pipeline network construction, low transmission network utilization rates, and high consumer prices in China. This paper proposes a combination of multi-agent and input-output models to outline natural gas transmission regime programs and examines the effects of mandatory separation of transmission networks from production and services, based on available data from 2014 to 2016. Three scenarios are set up including the basic condition (BAU) and two types of reforms, namely ownership unbundling (STRIP) and internal reform at company level (INTREF). Then a set of evaluation indicators are established, namely profit changes of three large oil companies, investment in pipeline networks, and user prices, as well as total output, added value, and price changes in related industries. The results show that, by 2030, the relative change rate of investment for STRIP will increase by 93.45% while the change in INTREF is −33.49%. Moreover, natural gas price under STRIP will decrease 27.12%, which is a decrease almost three times that under INTREF. It can be concluded that STRIP is more conducive to promoting the efficiency of natural gas transmission compared with INTREF. However, it may be time consuming for natural gas companies to introduce competitive social capital and gradually diversify their investments. [ABSTRACT FROM AUTHOR]

This paper assesses the thermal performance of an office building with an intermittent occupancy pattern, designed according to three construction scenarios. Annual simulations are carried out using TRNSYS software considering a Typical Meteorological Year (TMY) of six Moroccan cities referring to the representative zones of the recent Moroccan climatic zoning. The energetic and environmental performance of various passive energy efficiency measures are evaluated and discussed. The major finding of this work is that these energy measures can have a positive influence on reducing carbon footprint of the considered building. Annual loads can be reduced by about 20% in Agadir, 48% in Tangier, 53% in Fez 56% in Ifrane, 31% in Marrakech and 41% in Er-rachidia. [ABSTRACT FROM AUTHOR]

This paper presents a hybrid process combine micro reciprocated wire-EDM which uses reciprocated travelling wire with 50 μm diameter as tool electrode, with the precision forging, achieving the economical and high-efficiency sustainable production of micro gears. A micro gear mold with 0.1 mm module and 10 tooth number is devised, and the 14.5 μm mold fit clearance is determined by analyzing the established mold matching model and conducting the numerical simulation of precision forging. During the micro reciprocated wire-EDM of micro gear mold from SKD11, the basic experiments are performed to study the effect of the main parameters on machining accuracy and productivity, and whilst the proper machining parameters are obtained. The micro gear punch and die are successfully fabricated by micro reciprocated wire-EDM, showing good surface quality with 0.90 μm and 0.83 μm Ra respectively, and low dimensional deviations of ≤1.3 μm and 2.1 μm respectively. Finally, the precision forging of the micro gears are conducted on ultrafine grained (UFG) high purity copper by the machined micro gear mold. The forged micro gears have high forming precision with ≤4.1 μm deviation from the micro gear mold and smooth surface with 0.86 μm copied from the micro gear die cavity, verifying the feasibility of the proposed method for the sustainable production of micro gears. [ABSTRACT FROM AUTHOR]

The construction industry in Hong Kong has been exposed to serious housing production issues such as insufficient manpower, safety, environmental concerns and inefficient housing supply. Prefabrication housing production has shown as efficient construction model which enables to overcome these issues and it is applied in construction industry in Hong Kong. In this paper, hybrid modeling techniques that combine system dynamics and discrete event simulation are used to analyze the interrelationships of schedule risks within the six-day cycle assembly of prefabrication housing production. Moreover, a hybrid dynamic model is developed to simulate and evaluate the impact of schedule risks on the schedule performance of the six-day cycle assembly of PHP via the Anylogic software package. The resulting model is validated by data which is collected from a PHP project in Hong Kong. Based on the simulation results, the first most influential level contains five schedule risks, namely, inefficient verification of precast components because of ambiguous labels, misplacement on the storage site because of carelessness, owner crane breakdown and maintenance, slow quality inspection procedures, and inefficient design data transition that cause average schedule delays of more than 300 min. The second most influential level includes delay of the delivery of precast element to site, design information gap between designer and manufacturer, installation error of precast elements, and logistics information inconsistency because of human errors, with average schedule delays less than 300 min and greater than 200 min. Design change, low information interoperability between different enterprise resource planning systems, and inefficiency of design approval belong to the third level that imposes the least influence on the schedule delay of the assembly. This research contributes to the current knowledge of the management of prefabrication construction by developing an effective model that offers an in-depth understanding of how schedule performance of PHP is dynamically influenced by interrelationships of various risk variables. Also, it provides an experimental platform for simulating and analyzing schedule risks that significantly affect the schedule performance of the six-day cycle assembly of prefabrication housing production. Such critical schedule risks could be identified and managed prior to the implement of prefabrication housing production projects. Compared with traditional techniques, the hybrid dynamic model simultaneously considers macro and micro levels, thereby enabling project managers to gain a deeper insight into schedule management and acquire a multidimensional understanding of schedule delay. [ABSTRACT FROM AUTHOR]

The paper is focused on the application of solvent extraction for the recovery of rare earth elements from sulfuric leaching solutions obtained by the dissolution of fluorescent powders of lamps. The efficiency on rare earths extractions of three extractants, Cyanex 272, Cyanex 572 and D2EHPA in kerosene were investigated as a function of pH levels. Similar extraction for all the rare earths elements were observed, but the tests performed with D2EHPA showed that for pH values less than 1, yttrium and terbium could be extracted with yields higher than the other rare earths. The orders of the extraction were determined: yttrium ≥ terbium > gadolinium ≥ europium > cerium ≥ lanthanum. Further tests showed the optimal conditions, under the investigated ones, to extract yttrium with traces of terbium and cerium from sulfate leaching solutions. According to the experimental results, operating conditions of extractions were proposed in order to establish the guidelines for the following stripping and operation steps to recover rare earths selectively or at least in groups of them. A simulation of the proposed process was performed using a specific software in order to define the mass and energy balance of the entire recycling treatment of spent lamps. [ABSTRACT FROM AUTHOR]

In this paper, we report techno-economic analysis for CO 2 reforming of a medium-grade landfill gas in a membrane reactor (MR) for a H 2 production capacity of 7 m 3 h −1 in Korea. Parametric studies for the effect of key operating conditions like a H 2 permeance, a H 2 O sweep gas flow rate, and temperature on the performance in a conventional packed-bed reactor (PBR) and a MR were conducted using Aspen HYSYS ® , a commercial process simulator. Based on process simulation studies, economic analysis was carried out to find a unit H 2 production cost for both a PBR and a MR. Respective unit H 2 production costs of 9.72 and 6.46 $ kgH 2 −1 were obtained for a PBR and a MR showing about 34% reduction in the MR. Sensitivity analysis was employed to identify key economic factors to determine a unit H 2 production cost with labor the most influential factor for both reactors. Probability analysis (PA) was performed with influential factors based on a Monte-Carlo simulation method as uncertainty analysis and a cumulative probability (CP) curve was created for a PBR and a MR under various discount rates from 2 to 10% and key factor ranges from ±10 to ±40%. PA using stochastic approach provided a wide range of a unit H 2 production cost coupled with its probability and a critical CP value at which the effect of key factor range on a unit H 2 production cost was reversed. [ABSTRACT FROM AUTHOR]

In this paper, a blockchain-enabled relay-aided wireless network for sustainable e-agriculture is investigated, where best relay selection scheme based on the maximization of equivalent signal to noise ratio/signal to interference ratio (SNR/SIR) is considered. The performance of best relay selection under α − μ channel are derived in the paper, where closed-form expressions for transmission successful rate (TSR) and overall communication throughput (OCT) with and without interference are obtained. From derivation results, as the number of potential relay nodes increase, TSR and OCT performance will be ameliorated correspondingly. Numerical simulations have been performed to validate the correctness of our derivations. [ABSTRACT FROM AUTHOR]

The production of stainless steel begins by melting of scrap in melt shop that is known as one of the most electricity intensive processes. Volatile and uncertain renewable energy sources cause high fluctuations in electricity prices and thus usually higher costs for the final user such as a melt shop. This paper presents an integrated production and electricity optimization system that can help the melt shop to adjust its production schedule to volatile electricity prices and thus lower its costs. An existing production scheduling optimization system based on a continuous-time mixed-integer linear programming model has been further developed to account for electricity costs as well. It deploys an intelligent heuristics which decomposes the overall optimization problem into several sub-problems of smaller size in order to achieve faster and more robust solution. The electricity-aware optimization system has been successfully tested and implemented in a melt shop where it managed to reduce electricity costs by around 3%. At the same time, the system has improved coordination between different production stages, and thus made the entire melt shop more flexible, agile and responsive to unexpected events. The system has also been recognized as a very useful tool for running various simulations, what-if analysis and business scenarios on the melt shop in order to identify bottlenecks and further increase its production rate. [ABSTRACT FROM AUTHOR]

Building Information Modelling (BIM) is a digitalised technology under a collaborative working platform. Certain aspects of sustainability have been highlighted in recent BIM studies; however, no prior in-depth review has focused on BIM standards or guidelines and its uses for sustainability. This paper provides a mixed review to determine the current state-of-the-art BIM development for sustainability. A systematic review approach was adopted to analyse two main sources of literature, namely, BIM standards and guidelines; and peer-reviewed academic publications. The result reveals that although there has been a significant amount of research and development about the use of BIM during various project phases, little work has been conducted about how it could be applied in refurbishment and demolition. Certain significant insights and implications have been uncovered, namely: (a) new BIM tools are required for assessing sustainability criteria; (b) the need for improved interoperability among BIM software and energy simulation tools; (c) BIM uses into various aspects of refurbishment and demolition have to be streamlined; and (d) an innovative procurement system is needed to adapt social sustainability into the project. [ABSTRACT FROM AUTHOR]

The geological and ecological (geo-ecological) environment of the coastal coal-mining city is a basic element for human subsistence, and it connects the regional economy with social sustainable development. Using Longkou, a coastal mining city, as an example, a geological and ecological environmental quality assessment was conducted based on spatiotemporal big data. Remote sensing images, a digital elevation model (DEM), and precipitation and interpolation processing were used to generate factor layers. A synthetic evaluation index system was set up, including physical geography, geological conditions, mining intensity, ecological environmental recovery and geological hazards associated with mining. Moreover, an analytical hierarchy process was used to calculate the factor weight of each evaluation factor, and a consistency check was performed to build an assessment model of the geo-ecological environment of Longkou. The results indicate that multi-factor spatiotemporal big data provide a scientific assessment of the geo-ecological environmental quality with indispensable data and methods. The spatial distribution of geo-ecological environmental quality presented clear specialization of zonality, showing poor quality in the coastal coal mine ore concentration area and good quality in the inland and mountainous areas of Nanshan Mountain. The geo-ecological environmental quality of Longkou was divided into 5 levels as worst, poor, middle, good and better districts. The good and better districts accounted for 76.763% of the total area of the assessment region, indicating that the geo-ecological environmental quality of the study area was in good condition. The mining intensity and ecological environment recovery were major factors in determining the regional variation of the geo-ecological environment of Longkou. The possible causes inducing uncertainties and limitations in evaluation of the geo-ecological environmental quality were discussed. The model combining AHP with GIS proposed in this paper is an effective means of evaluating regional geo-ecological environmental quality. [ABSTRACT FROM AUTHOR]

Energy consumption in five-axis machining can be extremely large, especially for processing large-sized parts such as blades and dies, which often take hundreds of hours to machine. Once the specific machine tool configuration is given, one important objective in planning a five-axis machining operation is to reduce the total amount of energy consumption, which is not only particularly pertinent for mass production type operations but also plausible in today's energy-conscientious environment. While past research in this subject has been mainly focusing on finding better machining or processing parameters such as the cutting depth, feed rate, spindle speed, etc., in this paper, we study the fundamental problem of how to plan a five-axis tool path for machining an arbitrary free-form part surface on a given type of machine tool so that the total amount of energy consumption can be reduced, as compared to a traditional tool path, with everything else – e.g., the cutting depth, feed rate, spindle speed, maximum scallop-height, etc. – being equal. Towards this goal, an algebraic model called machine dependent energy potential field is formulated on the part surface, which encapsulates the specific power demand at any cutter contact point and along any feed direction. With this potential field, a simple tool path generation method is proposed that strives to find a good balance between the best fitting to the potential field (to minimize the total energy consumption) and the desired streamline patterns of the tool path. Experiments of the proposed method are carried out in both computer simulation and physical cutting, and the results are compared with that of some popular tool path generation methods such as the iso-scallop height method. The remarkable more than 25% savings in total consumed energy by the proposed method confirm the original motivation – designing better tool paths adaptive to the given specific machine tool is a powerful approach to reducing the total consumed energy, perhaps in general more effective than the passive selection of machining parameters which often have little room to adjust due to many constraints (e.g., the feed rate is highly regulated by the machine's controller during the cutting). [ABSTRACT FROM AUTHOR]

Resource conflict management is an increasingly interesting topic for both scientific advancement and policy analysis. This study provides decision makers with a data-driven tool as a valid support to institutional action in planning and implementing policies. The probabilistic network model here proposed is built using (1) historical data and (2) a general taxonomy on world resource conflicts. Predicting the most likely conflict outcome is a prerequisite for carrying out some scenario building, which is also illustrated in the paper. However, the strength of our study lies not only in the prediction model, which takes into account specific political, socio-economic and geographical features of the areas involved in resource conflicts, but also in the statistical approach proposed herein for assessing the impact of various policy decisions on conflict dynamics and outcome. The empirical analysis shows that economic and social factors play a central role not only as triggers of claims on the use of natural resources, but also on the salience and persistence of the conflict. Moreover, from scenario simulations it appears that bilateral negotiations most likely drive conflicts in coastal areas (biodiversity protection etc.) to end with an agreement between the parties. Not only the importance of economic interests on coastlines is much higher than in other areas, but also issues on the preservation of natural site and biodiversity are more likely to insist on littorals than in a general framework. [ABSTRACT FROM AUTHOR]

By means of a system dynamics computer simulation model, this paper analyzes the systemic effects of combining multiple product design and business model strategies for slowing and closing resource loops in a circular economy. In the model, green (i.e., recycled) and brown (i.e., traditional linear) products, as well as products under a PSS model, flow in a closed-loop supply chain. The model structure covers issues related to product design, product use and replacement, second-hand use, product discard, and finally, collection and processing for product recycling. Results from this research provide insights into the relationship between design considerations at the beginning of a product's life and their implications for the product's take-back stage when a new manufacturing cycle begins. The main contributions of this paper are the considerations of time delays and reinforcing feedback loops in the design of an effective closed-loop supply chain. [ABSTRACT FROM AUTHOR]

The industrial scale production of biodiesel, the most common biofuel, requires innovative solutions to become more and more competitive with a reduced environmental impact. Microalgae are the most promising feedstock for biodiesel production since they are grown on non-arable areas and reduce the greenhouse gas emissions as well. The oil extraction is the competitiveness bottleneck, largely impacting the overall process cost. Oil extraction using ionic liquids is considered a promising technique, which has the chance to become a benchmark for large scale applications. In this paper a novel process simulation of ionic liquid operation is developed, implemented by Aspen Hysys V7.3 ® . The chosen ionic liquid is Butyl-3-methylimidazolium chloride, a green solvent; since it is a non-conventional compound, a method to compute its properties through a thermodynamic model is provided. Moreover, a process scheme has been set up and simulated, composed of a lysis reactor, in which the ionic liquid is added for oil extraction, and a three phase separator, with recycle lines and several heat exchangers for heat recovery. Mass and energy balances have been carried out. The main results allowed to calculate the recovered oil as a function of the ionic liquid to dry biomass weight ratio (with assuming a bio-oil extraction yield of 100) and as expected, the bio-oil recovery yield increased at decreasing temperature. However, a complete recovery is not feasible, due to the physical constraints in the thermodynamic model hypotheses. Albeit some simplifying hypotheses for the thermodynamic properties, the novelty of this work is that it reports results of a process simulation, providing indication for industrial technological implementation coming from a professional tool for process simulation and control. [ABSTRACT FROM AUTHOR]

Designing a sustainable system of recycling used mobile phones (UMPs) is an urgent concern in terms of cleaner production ideas. In this paper, sustainability of a UMP recycle system is improved by reutilization of the existent well-developed mobile phone sales network, and readiness of customers to participate in recycling is promoted by buy-back prices and convenience. Consequently, a new integrated optimization model is built to maximize the total profit of recycling UMPs by choosing optimal buy-back prices, optimal collection points and optimal delivery routes. Particularly, the recycled quantity of UMPs in our model is a function with respect to the buy-back price and the chosen collection points from the existent physical sales network. Owing to complexity of this built model, efficient algorithms are developed by alternately solving three subproblems so as to obtain its optimal policy. By numerical simulation, it is found that: (1) With reutilization of the sales network and promotion of customers' readiness, an optimal recycle network can be designed by the proposed approach; (2) Reutilization of the sales network can greatly improve sustainability of the UMP recycle system; (3) The maximum recycling profit is closely related with real values of UMPs, and our model and algorithm can provide a threshold to guarantee a profitable recycle system; (4) Choosing optimal collection points mainly depends on their popularity to customers. [ABSTRACT FROM AUTHOR]

The cement industry sector is one of the largest carbon emitting industrial sectors, and due to the effect of global warming sustainable cement production is increasingly gaining on importance. Controlling the combustion of coal and the thermal degradation of limestone, the two main thermo-chemical processes that occur inside a cement calciner, is of significant importance, since these processes have a direct influence on the cement quality, pollutant formation and overall energy efficiency of the cement manufacturing process. One of the possibilities for the improvement and control of these thermo-chemical processes are Computational Fluid Dynamics – CFD simulations. The results gained from these simulations are being increasingly used to enhance the efficiency of cement production, since they improve the understanding of the flow characteristics and transport phenomena taking place inside the cement calciner. The purpose of this paper is to present that a more energy efficient and sustainable cement production can be achieved by deploying CFD simulations in the process of cement production. The numerical models of limestone thermal degradation, also known as the calcination process, and pulverized coal combustion were developed and implemented within the commercial computational fluid dynamics code FIRE, which was then used for the analysis. The developed models are based on the solution of Navier–Stokes equations for the gas phase, and on the Lagrangian dynamics for the discrete particles. A three dimensional complex geometry of a real industrial cement calciner was used for the CFD simulation. The information obtained from this numerical simulation, such as the distribution of particles, distribution of temperatures and the concentrations can be used for better understanding of particle kinetics and pollutant emissions from the given cement calciner and also for its further investigation and optimization. [ABSTRACT FROM AUTHOR]

Diesel engines account for approximately 50% of new passenger-car sales in the European market and are the major contributor to pollutants that adversely affect human health and the environment. The most adverse pollutants emitted by the combustion of diesel fuel are NO x , soot, CO and HC. Numerous studies have been carried out to determine the influence of engine design, fuel injection, fuel-air mixing and combustion on pollutant emissions. Information gained through experimental research of in–cylinder processes is limited, and the body of knowledge can be improved by the use of numerical modelling and computer simulations. Computational Fluid Dynamics (CFD) has become a valuable tool that decreases the time and the cost of experimental research. Therefore, CFD is being increasingly used in development of combustion systems. This paper presents how the development of CFD models is the proper approach towards achieving a cleaner and more sustainable transportation sector. The physical models for the liquid fuel disintegration, evaporation and pollutant formation are used and implemented into the commercial CFD code FIRE. The models are capable of predicting complex in–cylinder processes and, ultimately, the formation of pollutant emissions. The results from numerical simulations, such as NO x and soot concentrations, in–cylinder pressure and temperature are found to be in good agreement with the existing experimental data. [ABSTRACT FROM AUTHOR]

Abstract: This paper develops a framework for the modeling and analysis of a complex global supply chain network with corporate social responsibility (CSR) through integrated environmental decision-making and risk management. Through a multilevel global supply chain network, we model the multi-criteria decision-making behavior of the various decision-makers (manufacturers, retailers, and consumers), which includes the maximization of profit, the minimization of emission, and the minimization of risk. We propose a network performance measure for the evaluation of global supply chain network. We measure the impact of globalization on supply chains’ CSR decision-making and analyze the effects of CSR on prices, product flows, and the global supply chains efficiency. We found that a social responsible global supply chain network is more efficiency than a less responsible one. Moreover, the higher is the level of social responsibility of the network the lower is the price and therefore the higher is the demand for the product. [Copyright &y& Elsevier]

Abstract: In order to provide a reliable estimation of energy consumption under various machining conditions, an energy consumption model with high accuracy and well-defined coefficients is necessary to be developed. This paper presents an improved energy consumption model to characterize the relationship between process variables and energy consumption for material removal processes based on thermal equilibrium and empirical modelling. The improved model of milling process as a function of material removal rate and spindle speed has been tested and validated under various cutting parameters. Additionally, the values of the model coefficients are clearly defined, which will be easy to understand and explain each coefficient in the energy consumption model. The model coefficients were obtained using the statistic modelling based on experimental data. Experimental results show that the improved model is able to provide a reliable prediction of energy consumption for given process parameters with an accuracy of more than 96%. The good agreement between simulations and measured results led to the conclusion that the proposed model can be used effectively for the calculation of the total energy required by a machine tool system for face milling of a part. [Copyright &y& Elsevier]

Abstract: This paper originated as a part of a comprehensive research project designed to develop ecologically sustainable, environmentally friendly, resource- and energy-saving industrial process technology for the production of a wide class of phosphorus containing substances. The essential feature of the research was designed for the replacement of tubular heat exchangers with Plate heat exchangers (PHEs) and for the installation of these units in new locations in the processes to optimally improve energy efficiency and to prevent pollution. Despite the severe operating conditions in the production of phosphoric acid PHEs of various designs find the application in these processes. For such a corrosive environment as a phosphoric acid production plant, the Hastelloy G30 alloy is used as the material for the plates and synthetic rubber EPDM is used as the material for inter-plate gaskets. The analysis of the data shows, that using mixed groupings of plates in the unit allows one to obtain optimal solutions. The simulation of barometric mixing condenser recycled water cooling with plate heat exchanger shows the possibility of an application which minimizes the waste water pollution by closing the condenser cooling water circuit. Software was developed for calculations of units working both with liquid and phase changing streams. [Copyright &y& Elsevier]

Ventilation and dust removal is the most basic means of dust prevention in mines. In the paper, a highly simulated physical model of the goaf and multiple dust sources were established in order to obtain the optimal dust-removal air flow rate in the roadway. In addition, by combining the numerical simulation method, the influence of the flow rate on dust diffusion rules of the dust sources was analyzed. The research results showed that the mass concentration of the dust in the fully-mechanized working face was gradually decreased with the increase of the air flow rate at a certain range of 700–1600 m3/min. However, high air flow rate can cause the re-entrainment of the dust, contaminating the working environment again. It was confirmed that the optimal dust-removal air flow rate of the inlet air was within a range of 1500–1600 m3/min, which generated the lowest average mass of the dust in the working area suitable for normal operations. This range of air flow rate might be used as a reference in the mine ventilation design in order to provide the coal mine workers with a clean and safe production environment. In addition, the research method and results are of great significance to the formulation and development of effective dust control and dust removal cleaner production technology, and can be used as a reference for the ventilation design in underground projects such as non-coal mines and tunnels. Image 1003 • The innovative highly simulated physical model was established. • The effectiveness of numerical simulation was verified by field measurements. • The dust diffusion law under different air flow rate conditions was analyzed. • The optimal dust-removal air flow rate is obtained. [ABSTRACT FROM AUTHOR]

Large amounts of titanium-bearing blast furnace slag have been dumped in China, resulting in serious environmental contamination and a waste of precious titanium resource. At present, a process for recovering titanium from titanium-bearing blast furnace slag has been developed. Unfortunately, current size reduction techniques fail to meet the material size requirements. In this paper, a particle size controllable jet milling technology was proposed based on the idea of one-time collision between the particle and the target. To better control the breakage size, computational fluid dynamics was used to model the new jet mill giving a detailed understanding of the mechanisms. Simulated results showed that the acceleration region of the low velocity fluid was located inside the ejected stream. The velocity at which the fluid hits the target was relatively uniform. It indicated that the new jet mill was advantageous for obtaining a pulverized product having a narrower particle size distribution. Experimental results showed that the excessive size reduction was effectively reduced. The average mass fraction of the particles with the particle size of <30 μm was 19.0%, 30–150 μm was 72.8%, and >150 μm was 8.2%, meeting the requirement for titanium recycling from titanium-bearing blast furnace slag in industry. This study provides a feasible method for reducing particle size to a desired distribution to promote resource sustainable utilization and pollution reduction in an environmentally friendly way. Image 1069 • Particle size control is first identified as the key to Ti-BFS recycling. • One-time collision concept is put forward to control particle size of fracture. • Particle size controllable jet milling system is proposed and established. • Ti-BFS is crushed to the desired particle size distribution. [ABSTRACT FROM AUTHOR]

Rubber replanting is a key factor in sustaining natural rubber supplies because it replaces less productive rubber trees with fully productive ones. However, the time taken for rubber trees to become fully productive (approximately 6 years) can cause significant impacts on shorter-term rubber supplies. In addition, replanting can have environmental impacts, such as reduction of carbon stocks because immature trees convert less CO 2 than mature ones, and social impacts, such as reduced need for tappers, the highly skilled employees who harvest latex from rubber trees, during the immature phase of trees' lives. Early discussions with Indonesian natural rubber stakeholders highlighted a demand for methods and tools that allow the consideration of these impacts when formulating replanting policies. This paper proposes an approach to support the formulation of sustainable replanting policies in the Indonesian natural rubber supply network that allows users to consider trade-offs between three factors: economic, social and environmental. The approach uses the composite indicators method to represent the impacts of replanting on the sustainability of the supply network. These indices are used to drive computer simulations with a view to finding optimal replanting policies for given situations. The approach is illustrated through an application to the formulation of sustainable replanting scenarios in the Langkat, Deli Serdang, Asahan, Simalungun and South Tapanuli Districts at North Sumatera Province Indonesia. • Rubber trees have three lifecycle phases: immature, productive, less productive. • The balance of trees in a supply network is managed with replanting quotas. • Replanting quotas and policies impact all three dimensions of sustainability which are quantified using composite indices. • These indices are utilized in network simulations that use a novel hybrid approach to find optimal allocation quotas. • Simulation results identified different optimal quota allocations for each district. [ABSTRACT FROM AUTHOR]

This paper examines an Oscillating Water Column (OWC) model, where the air chamber is represented as a dry air–water vapour mixture, based on the thermodynamics of a real gas. The novelty of this study consists of the inclusion of humidity effects on the general performance of the OWC and its coupling with the radiation–diffraction problem of the device. Using FLUENT®, a numerical 2D flume is built to simulate wave–induced flow in the OWC. Air phase properties are adjusted to represent the presence of moisture. Turbine linear performance, according to a standard Wells turbine power take–off system, is simulated by means of an Actuator Disk Model (ADM). Numerical outputs are compared with analytical solutions of the classic OWC radiation–diffraction problem, in which the theoretical real gas model is embedded. Results show that the use of real gas thermodynamic theory reduces considerably the predicted power output of OWC devices, with theoretical losses reaching 50 % in certain cases. The effect of humidity mitigates resonant conditions. Techno–economic considerations justify the inclusion of real gas theory to achieve competitive devices. [ABSTRACT FROM AUTHOR]