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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]

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]

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]

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 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]

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]