Material Flow Model Research Articles

Resource recovery and low carbon transitions: The hidden impacts of substituting cement with imported ‘waste’ materials from coal and steel production

Abstract Here we investigate the increasingly complex relationship between the resource recovery practices of the UK concrete industry and ongoing low-carbon transitions taking place in electricity and steel. Reductions in UK coal-based electricity and primary steel production are reducing domestic availability of residues – coal ash and steel slag – that are used to replace cement in concrete; for decarbonisation purposes and to increase concrete quality. This is leading to an unusual mass-transportation of ‘wastes’ from the Global South to Global North. Focusing closely upon the mitigation pathways of concrete producers, we develop an inter-industry model of material flows, and a diversity of scenarios and sensitivity tests, to consider how resource recovery practices and carbon emissions of the three sectors may evolve. A continuation of domestic shortages in waste-derived cement substitutes appears inevitable and future international shortages possible. But even if foreign producers supplied enough cement substitutes to meet UK demand, the broader carbon implications of such trade may be far from benign. Using a revenue-based approach to allocate emissions to coal ash leads to a wide range of embodied carbon estimates – from relatively low (0.15 t.CO2/t.ash) to exceeding that of traditional Portland cement (1 t.CO2/t.ash). However, the carbon associated with internationally traded recovered resources currently stands behind a ‘double-blind’ system of accounting: emissions do not register in the conventional territorial accounts of the importing country and they may be hidden from its consumption-based accounts as well. The impacts of such trade and related carbon accounting conventions are unclear and we emphasise the need for further investigation. To this end, our results demonstrate the importance of incorporating highly interconnected sectors and international trade into analyses of low-carbon transitions, and highlight the challenges this presents for designing appropriate policies, accounting frameworks, and interdisciplinary impact assessment methods that look beyond sectorial and national horizons.

Statistical calibration and uncertainty quantification of complex machining computer models

Abstract Finite element based machining process models are used in research and industry for process design and optimization. These models require a constitutive description of the material behavior to accurately model and predict process responses such as cutting forces, temperatures, and residual stress. Calibration of these models to low-strain uniaxial dynamic compression experiments can be troublesome since the machining process generally imposes much larger strains than uniaxial compression. Calibration of finite element models directly to machining data is generally difficult since the models are computationally expensive and nonlinear optimization methods for estimating the unknown calibration parameters yield non-unique solutions and require many iterations. In this work we utilize a nonstationary Gaussian Process surrogate model to emulate the finite element response and calibrate to experimental orthogonal cutting tests using a Bayesian inference framework. We assume that the material yield behavior can be described by the Johnson-Cook material flow model. We find that the nonstationary Gaussian Process model is an good surrogate for the complex finite element model. Cutting forces measured from orthogonal tube turning experiments were used for calibration. Validation is performed using a separate response variable - the cut chip thickness. Calibration results illustrate a preference for material models with low hardening rates, which alleviates issues such as over-prediction of strain hardening behavior when using the Johnson-Cook material flow model. The Bayesian formulation also captures the uncertainty in the Johnson-Cook parameters, which can be used to quantify the uncertainty in the machining process responses. The methods presented here are general and can be used for more complex constitutive and tribological models for machining and other complex manufacturing processes.

Shedding Light on the Anthropogenic Europium Cycle in the EU–28. Marking Product Turnover and Energy Progress in the Lighting Sector

Phase-out strategies for incandescent bulbs in favor of advanced energy-efficiency lighting systems such as fluorescent lamps and solid-state technology have considerably reduced the energy use for lighting, but have also resulted in dependence on many critical materials like rare earth elements and shifted the attention to sustainable use and recovery of resources. In this work, a dynamic material flow model was developed to analyze the socio-economic metabolism of europium in the EU–28. The analysis shows that europium marked product turnover and progress in lighting efficiency, with this element being employed both in traditional and novel lighting technology to provide luminescence. The results also demonstrate that the current anthropogenic reserve could constitute an attractive source of secondary europium with substantial potentials for environmental benefits. However, nonexistent recycling and market forces hinder strategies for material circularity. In particular, the transition from fluorescent lamps to solid-state technology is quickly decreasing the demand for europium. This trend adds further constraints to the creation of a sustainable recycling industry for europium, with primary sources that might remain the preferable route to supply phosphors to future lighting systems.

Framework for WASH Sector Data Improvements in Data-Poor Environments, Applied to Accra, Ghana

Improvements in water, sanitation and hygiene (WASH) service provision are hampered by limited open data availability. This paper presents a data integration framework, collects the data and develops a material flow model, which aids data-based policy and infrastructure development for the WASH sector. This model provides a robust quantitative mapping of the complete anthropogenic WASH flow-cycle: from raw water intake to water use, wastewater and excreta generation, discharge and treatment. This approach integrates various available sources using a process-chain bottom-up engineering approach to improve the quality of WASH planning. The data integration framework and the modelling methodology are applied to the Greater Accra Metropolitan Area (GAMA), Ghana. The highest level of understanding of the GAMA WASH sector is achieved, promoting scenario testing for future WASH developments. The results show 96% of the population had access to improved safe water in 2010 if sachet and bottled water was included, but only 67% if excluded. Additionally, 66% of 338,000 m3 per day of generated wastewater is unsafely disposed locally, with 23% entering open drains, and 11% sewage pipes, indicating poor sanitation coverage. Total treated wastewater is <0.5% in 2014, with only 18% of 43,000 m3 per day treatment capacity operational. The combined data sets are made available to support research and sustainable development activities.

Prospective nanomaterial mass flows to the environment by life cycle stage from five applications containing CuO, DPP, FeOx, CNT and SiO2

Many new nanoapplications containing engineered nanomaterials (ENM) are introduced to the market every year. Because they have the potential to release ENM to the environment during their life cycle, it is desirable to investigate the amounts of ENM that could be emitted to the environment before they occur. In this research, we created ENM mass consumption scenarios and modelled prospectively the ENM mass flows produced at each life cycle stage of five nano-enhanced applications, using a probabilistic material flow analysis method and a bottom-up approach. The nanoapplications are: (i) wood coating containing CuO; (ii) car bumper with DPP (organic pigment) or (iii) Fe2O3 (inorganic pigment); (iv) polymeric car part with CNT; and (v) pancake mixture with SiO2. The simulated flows were used to (a) describe the potential ENM mass flows in Europe and to determine the distribution of the mass at the end of each LC stage among the technical and environmental compartments analyzed; (b) to compare the flows produced by single applications with the total flows from all existing applications; (c) to estimate the release concentrations in environmental compartments; and (d) to evaluate the origin of the flows by LC stage. The total flows were taken from previously published research or newly modelled in the case of CuO and DPP. The results show that most ENM mass flows from each single application occurred during their end-of-life stage and the main receiving compartments were the landfill (except pancake mixture application) or the agricultural soils and sediments (only pancake mixture). In general, a substantial proportion of the ENMs was either eliminated or transferred to recycling facilities, from where the recovered material fractions containing ENMs could be used as secondary raw materials. The comparison with the total flows shows that only the wood coating would result in a considerable increase of the ENM mass flows to the environment, given the market penetration assumed (1%). The use of the pancake mixture would produce the highest flows into the environment among the different ENMs analyzed, as a consequence of the high direct release during its end-of-life. The assessment by LC stage allowed to stress the role of manufacturing in dominating the flows into the environment for some applications. In general, our assessment shows the potential of the existing material flow modeling methods to investigate prospectively the emissions of ENM mass into the environment from specific applications.

An economic model of circular supply network dynamics: Toward an understanding of performance measurement in the context of multiple stakeholders

AbstractThe circular economy (CE) is increasingly being seen as a way in which organizations and economies can become environmentally sustainable. In this context, a key challenge facing multiple‐stakeholder collaborations in circular supply networks (CSNs) is the need to coordinate activities, as well as to monitor and benchmark sustainability performance. The limited formal analysis of CE production dynamics and performance indicators of activities in the CSN has contributed to these challenges. To address this we develop an economic model of material flow in a CSN that incorporates multiple stakeholder effects, and two novel performance indicators that: (i) estimate the joint effects of the speed of recycling, and the effectiveness of collection and conversion of recycled material on production; and (ii) a measure of the upper bound production possibilities for a given recyclable material cycling through a CSN. These indicators will be informative for monitoring, benchmarking and incentivizing performance across CSNs and informing public policy debates and strategies.

Examining Fuel-Cycle Scenarios with the Safeguards Analysis Toolbox

SafeGuards Analysis (SGA) is a toolbox developed to allow engineers and scientists to create detailed simulations of safeguards material control and accountability simulations. SGA accepts material flow data from an external material flow model and can be used with any existing fuel cycle or material control code. This paper examines some new developments to the SGA code that allow the code to consider material losses over long time frames. The first scenario described in this paper examined an enrichment facility consisting of two material balance areas (MBAs). Cumulative sum and basic control chart tests were evaluated for a case involving a loss of material from both MBAs simultaneously and a case in which material is removed from the facility over a timescale of double the one that the tests were calibrated to detect. A second scenario represents an entire fuel cycle consisting of four MBAs and two materials of interest (low-enriched uranium and plutonium). This scenario evaluated the calibrated safeguards system with three blind unidentified stream cases, with the goal of determining the calibrated system’s ability to detect where the material loss occurred in each case. SGA was able to produce the expected results for all of the examples examined in this paper, demonstrating that modules produced using the toolbox are capable of examining larger systems in realistic multi-MBA scenarios.

The study of material flow behaviour in dissimilar material FSW of AA6061 and Cu-B370 alloys plates

Friction stir welding is a solid-state joining process which proved to be very effective for similar low strength materials. However, the joining of dissimilar materials is far complex than the similar materials because of divergent material properties. The need to study friction stir welding of dissimilar materials is inevitable due to increasing demand of modern industries. In the current study, the joining of aluminium alloy (AA-6061) and copper alloy (Cu-B370) plates is accomplished for studying the material flow movement throughout welding zone. A novel material flow model for dissimilar material friction stir welding is proposed based on the temperature and strain rate dependent material properties. The model used the volume of fluid (VOF) approach in the commercial FVM package ANSYS fluent 14.5. Experiments are also conducted to validate the model with thermal profiles and optical micrographs. Furthermore, the effect of tool rotational and the welding speed are studied on the material movement. It is found that process parameter had a huge impact on the nugget zone formation during the welding. The tool rotaion and welding speed directly affect the amount of platisized material mixing.

The effect of remanufacturing and direct reuse on resource productivity of China’s automotive production

Abstract Remanufacturing and direct reuse are considered important measures for promoting the circular economy and improving resource efficiency. Automotive production is a typical resource- and energy-intensive industrial sector, and is a prime market for remanufacturing and direct reuse. Assessing the effect of remanufacturing and direct reuse on the automotive production industry from the perspective of resource efficiency will provide an important reference for improving understandings of remanufacturing and guiding relevant policies in a broader context. A literature review reveals few studies focusing on the resource efficiency of remanufacturing and direct reuse, and the relative lack of a generally accepted indicator to assess the resource efficiency of industrial processes. This paper promotes a new indicator, resource productivity of industrial process, and constructs a material flow model to calculate the resource productivity of China’s automotive industry. Results suggest that the indicator and its analytical model are effective tools to assess resource efficiency. Results also suggest that compared to a case where remanufacturing and direct reuse are not employed, adding these processes in China’s automotive supply chain would increase resource productivity of industrial process by 7.1% in a high efficiency scenario. Based on these findings, policy recommendations for applying the indicator at industry level and encouraging remanufacturing and direct reuse are provided.

Passive filling friction stir repairing AZ31-B magnesium alloy by external stationary shoulder

In order to repair the varied-shaped volume defect adjacent to metal structure surface, passive filling friction stir repairing using an external stationary shoulder was put forward. The material flow model during the repairing process was established to explain why the stationary shoulder improves the quality of repaired region. The relation between microstructures and microhardnesses was attained. The results reflect that the stationary shoulder can transfer more materials into the stir zone (SZ) and absorb more heat generated in the SZ. These effects are beneficial to not only avoiding the hole defect in the SZ, but also greatly refining the grain and then heightening the microhardness in the SZ top region. Therefore, the addition of the stationary shoulder plays an important positive role on the repairing process, especially when the extra filling material is used.

DETERMINATION OF THE OPTIMAL SCHEMES OF SOLID WASTE MANAGEMENT IN CITIES OF UKRAINE

A scheme of solid domestic wastes management is proposed. The scheme includes a separate two-stream collection of municipal waste, sorting, collecting of secondary raw materials, producing of RDF-fuel and storing a small part at a landfill equipped with a landfill gas collection system. With the help of objective data, expert assessments and calculations, the basic material and financial parameters of the main flows of the scheme are defined. The model of material, energy and financial flows is proposed, which allows evaluating the technical and economic efficiency of the MSW complex management. By example of Ivano-Frankivsk city it is shown that even at existing low tariffs for transporting this waste disposal, complex using of «cost» and «profitable» elements allows you to create a self-proclaimed MSW management system. All the technologies involved in the scheme have been successfully implemented in Ukraine. Bibl. 24, Fig. 7, Tab. 9.

Two-dimensional model of material flow in a screw channel with a fixed cover

Features of the viscous-plastic material flow through the screw channel are studied. A promising direction in this case is the transport models determined by the hydrodynamics of the phase transition. The author also analyzed the effect of dimensions on the flow rate of a viscous-plastic material. The material situated in the channel of the rotating auger and bounded by the fixed body will start to move in a translational motion along the channel due to the shear deformation that appears in it, this is where a forced flow appears. The main parameters that determine the volume flow rate are the depth and width of the channel, the diameter of the screw and the frequency of its rotation. A necessary condition for the existence of this flow is the persistence of shear stress in the material, which is possible only if the material has a certain viscosity. The condition of the return flow is the excessive pressure created by the resistance of the head. We assume the case when in these conditions the auger does not move. Then, under the action of pressure from the side of the head, the material will flow from it along the screw channel – in the opposite direction. The volume flow rate of the counter-flow also depends on the depth of the channel, on the diameter and length of the screw, on the viscosity of the material and on the pressure in the head. In practice, however, there is never a countercurrent in the auger channel, and the head pressure exerts a kind of limitation on the direct flow, which is theoretically viewed as a countercurrent, and the productivity of the screw supercharger is the total flow of the two flows. To account for the geometry of the channel, the author developed a mathematical model of the velocity head in a rectangular channel. The resulting equation makes it possible to determine the shear stress in terms of the shear rate of the material. Taking into account the symmetry and linearity of the velocity distribution in the channel with respect to its midpoint, an equation is obtained for the distribution of the shear rate along the height. The dependence, obtained as a result of the analytical solution of the two-dimensional Poisson equation, makes it possible to simplify considerably the calculation of the discharge-pressure characteristics of the extruder part of the screw presses for pressing vegetable oils with respect to the required screw rotation speed.

Mathematical Modelling of Material Flow during Friction Stir Welding of Aluminium Alloys

The paper presents the results of a mathematical model of the material flow during Friction Stir Welding (FSW) of aluminium alloys using a Finite Element Analysis. The authors presented their work on a two-dimensional visco-plastic model, using User Define Functions (UDF) in a commercial CFD code (FLUENT). The model developed was validated by microstructural investigations on experimental FSW joints and by a comparative analysis of temperature distribution field of the experimental FSW joint and numerical simulated model. The results confirmed that the mathematical model describes with a good precision the material flow and temperature field during FSW process.

Environmental risk assessment of engineered nano-SiO2 , nano iron oxides, nano-CeO2 , nano-Al2 O3 , and quantum dots.

Many research studies have endeavored to investigate the ecotoxicological hazards of engineered nanomaterials (ENMs). However, little is known regarding the actual environmental risks of ENMs, combining both hazard and exposure data. The aim of the present study was to quantify the environmental risks for nano-Al2 O3 , nano-SiO2 , nano iron oxides, nano-CeO2 , and quantum dots by comparing the predicted environmental concentrations (PECs) with the predicted-no-effect concentrations (PNECs). The PEC values of these 5 ENMs in freshwaters in 2020 for northern Europe and southeastern Europe were taken from a published dynamic probabilistic material flow analysis model. The PNEC values were calculated using probabilistic species sensitivity distribution (SSD). The order of the PNEC values was quantum dots < nano-CeO2 < nano iron oxides < nano-Al2 O3 < nano-SiO2 . The risks posed by these 5 ENMs were demonstrated to be in the reverse order: nano-Al2 O3 > nano-SiO2 > nano iron oxides > nano-CeO2 > quantum dots. However, all risk characterization values are 4 to 8 orders of magnitude lower than 1, and no risk was therefore predicted for any of the investigated ENMs at the estimated release level in 2020. Compared to static models, the dynamic material flow model allowed us to use PEC values based on a more complex parameterization, considering a dynamic input over time and time-dependent release of ENMs. The probabilistic SSD approach makes it possible to include all available data to estimate hazards of ENMs by considering the whole range of variability between studies and material types. The risk-assessment approach is therefore able to handle the uncertainty and variability associated with the collected data. The results of the present study provide a scientific foundation for risk-based regulatory decisions of the investigated ENMs. Environ Toxicol Chem 2018;37:1387-1395. © 2018 SETAC.

Dynamics of bisphenol A (BPA) and bisphenol S (BPS) in the European paper cycle: Need for concern?

Bisphenol A (BPA) is an industrial chemical used as an additive in conventional point-of-sale thermal paper receipts. Due to BPA being an endocrine disruptor and a substance of very high concern, the European Union (EU) has proposed to ban its use in thermal paper from 2020. Potential similarities in toxicological profiles have raised concerns that the use of bisphenol S (BPS) as a substitute for BPA may result in yet another situation of a problematic chemical being distributed in consumer products. This study provides a comprehensive evaluation of the current knowledge of BPA and BPS use in thermal paper and, based on dynamic material and substance flow modeling, quantifies potential effects of the BPA ban on future BPA and BPS flows within the European paper cycle. Based on available data and the modeling of BPA and BPS flows, approximately 200 t of BPS are estimated to be present in the current European paper cycle. The modeling further demonstrated that by substituting 50% of BPA, BPS amounts in the European paper cycle would increase more than fivefold over a modeling period of 60 years. In the same time, more than 90 t of BPA would still be circulated in European paper products. BPA alternatives other than BPS should receive additional attention, as very limited quantitative data currently exist. The results of this study quantitatively demonstrate that chemical bans alone are not sufficient to ensure clean material cycles, and so the effective regulation of potential substitutes needs to be implemented in parallel.

Tracking Construction Material over Space and Time: Prospective and Geo‐referenced Modeling of Building Stocks and Construction Material Flows

SummaryConstruction material plays an increasingly important role in the environmental impacts of buildings. In order to investigate impacts of materials on a building level, we present a bottom‐up building stock model that uses three‐dimensional and geo‐referenced building data to determine volumetric information of material stocks in Swiss residential buildings. We used a probabilistic modeling approach to calculate future material flows for the individual buildings. We investigated six scenarios with different assumptions concerning per‐capita floor area, building stock turnover, and construction material. The Swiss building stock will undergo important structural changes by 2035. While this will lead to a reduced number in new constructions, material flows will increase. Total material inflow decreases by almost half while outflows double. In 2055, the total amount of material in‐ and outflows are almost equal, which represents an important opportunity to close construction material cycles. Total environmental impacts due to production and disposal of construction material remain relatively stable over time. The cumulated impact is slightly reduced for the wood‐based scenario. The scenario with more insulation material leads to slightly higher material‐related emissions. An increase in per‐capita floor area or material turnover will lead to a considerable increase in impacts. The new modeling approach overcomes the limitations of previous bottom‐up building models and allows for investigating building material flows and stocks in space and time. This supports the development of tailored strategies to reduce the material footprint and environmental impacts of buildings and settlements.

Quantifying potential anthropogenic resources of buildings through hot spot analysis

This study estimates the amount of urban ores in Taipei City between 1965 and 2014 by analyzing data of the buildings through statistics and geographical information systems (GIS). Hot spot analysis (HSA) is introduced to assess the location of resources. Our results show that up to the year 2014, 186 Mton of construction materials were accumulated in Taipei, and the per capita total building material stock was 68 ton. In the short term, the hot spots with development potential are Da’an (Zone I) and Zhongshan (Zone II) Districts in Taipei City. Zone I (0.1 km2) stored 180 kton of materials; while Zone II (0.6 km2) stored 119 kton of materials. This study provides quantitative data on urban ores with high spatial and temporal resolution for enhancing material recycling planning and management. Material stocks could then combine with the material flow to build a dynamic material flow model for assessing the quantity of extractable urban ores, and the feasibility of exploitation in the future.

Modeling and Control of Bulk Material Flow on the Electromagnetic Vibratory Feeder

This paper presents the results of modeling, simulation and experimental research of the bulk material flow on the electromagnetic vibratory feeder (EVF). The model of the EVF was implemented in Simulink/Matlab and verified in the experimental research. It has been experimentally confirmed that the bulk material flow rate has its maximal value as far as excitation frequency is equal to the EVF mechanical resonant frequency. For certain bulk material flow rate, average value of excitation coil current of EVF has minimal value when named frequencies are equal. In addition to modeling of the EVF, the main contribution of this paper is implementation of flow control algorithm of bulk material on EVF, experimental verification of the adopted model and defines parameters that enable the selection of energy-efficient operating point of the EVF.

Improving interface morphology and shear failure load of friction stir lap welding by changing material concentrated zone location

The morphology of lap interface is the key factor to affect the tensile properties of friction stir lap welding (FSLW) joint. Choosing the pin length as research object, effects of material concentrated zone (MCZ) location on interface morphology and shear failure load of FSLW joint were mainly investigated. Based on 2024-T4 aluminum alloy with 3 mm thickness, four tools were discussed, whose pin lengths are respectively 2, 3, 4, and 5 mm. Material flow models of four different tools are established to explain how MCZ locations over, on, and below lap interfaces influence the formation of hook and cold lap morphology. For both configurations A and B of FSLW joint, lap shear failure load curves changing with pin length exhibit a “N” shape under the special rotating speed varying from 850 to 1000 rpm. The highest lap shear load of 25,665.34 N is attained under the pin length of 3 mm and the rotating speed of 850 rpm. The typical shear and tensile fracture modes are found and the fracture morphologies present ductile fracture.

Energy and material flow modelling of additive manufacturing processes

ABSTRACTAdditive manufacturing (AM) processes allow fabrication of three-dimensional complex parts. Due to the exact amount of material used during the manufacturing step, these new manufacturing processes offer great opportunities for sustainable manufacturing. However, existing studies on these processes focus mainly on energy consumption and information about resources consumptions and waste flows are still lacking. This study aims to quantify with accuracy inventory data of AM processes during the manufacturing step of the life cycle of products. In order to accurately assess the environmental impact of a product, a generic method for acquisitions and characterisation of inventory data for parts made by AM processes is proposed. This methodology focuses not only on the electrical energy consumption but also on material consumption. This paper also describes the development of a parametric process model, which provides to an operator, an accurate estimation of the environmental performances of the fused deposition modelling process.