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Hydrogen is considered a truly clean energy source with great potential for replacing fossil fuels. However, the special physical and chemical properties of this source make large-scale, safe, and efficient storage challenging, thus limiting its widespread use. Consequently, an underground hydrogen storage system inspired by underground methane storage and CO 2 geological sequestration has been proposed, and it is increasingly becoming a focus of research. Depleted oil reservoirs are ideal sites for such systems. Nevertheless, research on these types of underground hydrogen storage systems is limited to a few feasibility assessments, and the hydrogen seepage laws in reservoirs with residual oil are not well understood. In this paper, a study was conducted involving mathematical modeling and numerical simulation of underground hydrogen storage, which was converted from the SSZ low-permeability depleted oil reservoir in Bohaiwan Basin, eastern China, to reveal the seepage patterns between hydrogen and complicated in situ fluids (oil, gas, and water). First, a comprehensive analysis was conducted using numerous rock samples and experimental data to identify the composition, genesis, and distribution patterns of the sandstone reservoir, detailing its internal pore structure and fluid distribution postdepletion characteristics. Then, the hydrogen seepage properties in the presence of oil films in the three main throat types of low-permeability sandstone were analyzed, and corresponding mathematical models of the different throats were established. Finally, a numerical simulation of underground hydrogen storage was conducted to assess the impacts of various parameters, such as injection speed, reservoir heterogeneity, and residual oil saturation, on hydrogen seepage. The planar and vertical diffusion patterns of hydrogen were clarified, and the key factors affecting the efficiency of underground hydrogen storage were analyzed, offering suggestions for the establishment of stable and efficient underground hydrogen storage systems. • Selection and description of typical low-permeability reservoirs for UHS. • Mathematical model establishment for hydrogen percolation in porous rock. • Numerical simulation of the storage process of hydrogen. • Percolation laws of hydrogen in rock porous. [ABSTRACT FROM AUTHOR]

• Experiments were conducted to investigate rock breaking using high-pressure, high traverse speed water jets, matching the movement speed of the TBM disc cutter. • The relationship between traverse speed and the depth of water jet cutting was examined. • A deeper groove depth than penetration depth leads to a more effective rock-breaking outcome. • A water jet zoning arrangement method for eight-meter class TBM cutters is introduced. The disc cutting load of a TBM is insufficient to induce crack propagation in hard rock tunnels due to the high strength of the rock. High-pressure water jets, considered an auxiliary rock-breaking method, enhance the disc cutter's capacity to penetrate cracks by creating pre-existing fissures. In order to examine the correlation between cutting depth achieved by a high-pressure water jet operating at high traverse speeds and the penetration capability of TBM disc cutters, we conducted rock cutting experiments employing varying traverse velocities for the water jet. Additionally, we performed linear disc cutting experiments using full-size disc cutters equipped with grooves. These experiments were conducted using high-strength granite from China's Bei Shan region. We utilized the Discrete Element Software PFC2D to construct a rock breaking model based on Tyson polygons, enabling us to investigate the microfine influence mechanism of grooves with symmetry. The experiments involving high-pressure water jet grooving at high traverse velocities revealed a logarithmic decrease in groove depth as the nozzle's traverse velocity increased. These findings suggest that when high-pressure water jets are employed as an auxiliary method in TBM operations, increased distance from the center of the disc hob leads to higher traverse velocities, resulting in less efficient rock breaking. Nonetheless, increasing the nozzle diameter can enhance the rock-breaking effect. Linear disc cutting experiments indicate that, at a penetration depth of 4 mm, grooves with depths less than 4 mm have minimal impact on assisting in disc cutter rock breaking. However, when the groove depth exceeds 4 mm, there is a noticeable improvement in the disc cutter's breaking performance. The numerical simulation results provide initial validation for the linear disc cutting experiment. Lastly, considering the specific conditions of the Beishan tunnel, we propose a design scheme that involves the zoned arrangement of water jets. Additionally, we recommend appropriately reducing the rotational speed when employing high-pressure water jets as an auxiliary method for rock breaking. The research findings presented in this paper can serve as valuable references for the design and implementation of high-pressure water jet-assisted TBM cutter rock breaking. [ABSTRACT FROM AUTHOR]

• The effects of different recirculating flue gas ratios on corex gas combustion and different types of NOx generation rates were studied. • A flue gas interlayer structure between the gas and the internal secondary air passage can significantly reduce the NOx emissions of high calorific value gas and improve the emission reduction effect of flue gas recirculation technology. • A new type of burner with a wide range of application is designed, and the NOx can be lower than 100 mg/m3 when burning COREX gas. To tackle the problem of high nitrogen oxide (NO x) emissions and low combustion efficiency when burning COREX gas, a type of high-calorific gas that is a by-product of the Ouye furnace, a low-NO x burner with broad applicability was designed. In this study, the feasibility of flue gas recirculation technology applied to a swirl burner of COREX gas was investigated through Fluent numerical simulation, and the effect of central flue gas recirculation ratio on burner combustion characteristics and NO x generation rate was analyzed. The results indicated that the implementation of central flue gas recirculation reduced the NO x concentration from 288.4 mg/m3 to 101.48 mg/m3. To further reduce nitrogen oxide emissions, an interlayer structure for flue gas was proposed to be installed between the COREX gas and internal secondary air. Flue gas was extracted from the tail of the boiler and introduced into the interlayer structure, thereby delaying the fuel and internal secondary air mixing while achieving uniform diffusion of low-temperature and low-oxygen flue gas into the combustion zone. Compared with the structure without flue gas interlayer, the NO x concentration can be reduced from 101.48 mg/m3 to 61.54 mg/m3 by passing the flue gas through the central passage and flue gas interlayer with a mass ratio of 3:5.The study demonstrated that the low-NO x burner designed in this paper had sound inhibition effects on thermal and prompt NO x. Based on both actual operation and simulation results, it was observed that the outlet NO x concentration could be regulated within 100 mg/m3 across varying boiler loads. This marks the first application of a low-NO x burner for the combustion of COREX gas in China. [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]

This paper presents the investigation of a novel mini channel PV/T and thermal collectors combined heat pump system, using both experimental and theoretical methods. Data were produced under conditions typical for winter days in Lvliang, China. A simulation model is developed to conduct theoretical evaluation based on real-world conditions. The experimental and simulated electrical and thermal efficiency of PV/T panels, thermal efficiency of thermal collectors and COP of heat pump are compared. It is shown that the experimental and simulated results are in close agreement. The errors range from 4.0% to 9.1%, giving us confidence that this model is reasonable to predict the seasonal performance of the system. The experimental and simulated results of the system provide fundamental data for performance analysis in winter conditions and inform further improvements of similar systems in the future. • A novel solar assisted indirect-expansion heat pump system is constructed. • A unified computer model based on this system is developed. • Comparison between the experimental and simulated results are analyzed. • The simulation model is verified which can predict the annual performance. [ABSTRACT FROM AUTHOR]

Abstract Hot dry rock geothermal energy is a type of renewable energy with great development prospects in deep strata. However, it is quite difficult to construct an artificial reservoir. In this paper, deep large-dip-angle fault zone in the Yangbajing geothermal field in Tibet of China is used as a natural artificial reservoir, and a set of hot dry rock heat extraction schemes for such fault modes is proposed. A three-dimensional thermo-hydro-mechanical coupling model is established for the scheme to study the distributions of temperature, stress and seepage during the process of mining fault-mode hot dry rock geothermal energy. The temperature of #1 production well remains 445 °C after 22-year operation and it decreases from 445 °C to less than 200 °C after 15-year operation in #2 production well. The initial vertical stress near the injection well is 199 MPa, which decreases to 193 MPa after 1 year and remains unchanged. The specific water flow in the fault zone between the wells increases negatively and exponentially with the extraction time. The seepage resistance of the fault rock mass gradually decreases. The total effective heat production is 13130 MWa after 22-year operation. Highlights • Fault zone can be used to easily construct artificial reservoir in EGS. • Seepage resistance of fault rock mass gradually decreases with mining time. • Extracted water temperature exponentially decreases with mining time. • A geothermal power plant with capacity of 500 MW has more than 25-year lifespan. [ABSTRACT FROM AUTHOR]

The high speed railway, which acts as a safer and faster means of transportation, has grown rapidly around the world, especially in China. Meanwhile, the vibration induced by high-speed train (HST) arouses increasing concerns and cannot be ignored. This paper describes ground vibrations with three dimensional models formulated in the time domain using the finite element method (FEM). Absorbing boundaries and Rayleigh damping approach are used to prevent wave reflections from the artificial edges and to simulate the material damping, respectively. Investigations of ground vibration caused by unit load under different speeds and frequencies are given. An inclined classification of ground vibration and the sensitive frequency ranges of surface ground are then found. Moreover, the effects of subgrade treatment and sub-soil treatment on vibration isolation are discussed. It concludes that due to the attenuation effects of subgrade structures on high frequency range, noticeable reductions can be obtained in surface ground vibration. And when a high subgrade or a composite one is applied, the effects are better. The depth of sub-soil treatment would have more positive influence on ground vibration isolation and costs relatively less, compared with its replacement ratio and width. Negative influence may even occur when the sub-soil treatment width becomes larger. Additionally, some useful recommendations are proposed in this paper. [ABSTRACT FROM AUTHOR]

This paper searches for a deployment method with minimum sensor nodes to achieve agricultural intelligent monitoring. Because of the various features, topographies and complicated weather conditions, the selection of the location for deploying sensor nodes is difficult, especially in hilly areas. This paper puts forward a sensor node deployment algorithm for agricultural intelligent monitoring based on an optimized theory. It first develops a mathematical model for the node location selection. During the solution process, the features of the locations are of primary concern, as a location with more features is easier to choose than other locations. Next, a theoretical analysis and experimental simulation are carried out. Finally, OASNDFA is used in 3000 mu orange orchards in China. The result demonstrates that OASNDFA could perform relevant monitoring tasks with fewer monitoring nodes. [ABSTRACT FROM AUTHOR]

The optimization design of the open pit slope can ensure safety in production at the same time bring considerable economic benefits, so it is necessary to evaluate the stability of the initial excavation scheme of the high slope in an open-pit mine and optimize the initial slope angle according to the evaluation results. In this paper, an exhaustive study of Anyi open-pit mine in mouding County Yunnan province China has been made, and the following results have been achieved: (1)Confirmed the geological factors which affected the slope stability of open-pit mine; (2)Quantified the stability of the open-pit mine slope; (3) Under the premise of safety, the angle of the open pit high slope has been optimized on the base of the calculations of the open-pit mine high slope stability so as to ensure the maximum economic benefit. In this paper, the study area was divided into six zones. Firstly, qualitative analysis of slope stability was made by analogy method of engineering geology and stereographic projection method according to the orebody location, the properties of rock and soil in slope, the height of slope, and so on. The analysis shows that the preliminary design of slope angle is so large to ensure safety. Secondly, the stability of different slopes of a high slope is the quantitative analysis of different zones in high slope was made by two-dimensional limit equilibrium method and the finite difference method. In this paper, the mechanical parameters of rock are obtained by a laboratory test, and the stability of the high slope is quantitatively analyzed by two-dimensional limit equilibrium and three-dimensional numerical simulation. • Confirmed the geological factors which affected the slope stability. • Quantified the stability of the open-pit mine slope. • Under the premise of safety, the angle of the open pit high slope. • The preliminary design of slope angle is so large to ensure safety. [ABSTRACT FROM AUTHOR]

On account of the numerous discontinuities and multiple physics involved, the numerical evaluation of pollution propagation is computationally sophisticated and time-consuming. This paper proposes a new approach based on the unified pipe-network method to simulate nuclide migration in highly fractured rock masses. This method explicitly represents fracture networks with interconnected nodes and pipes in a spatial domain and applies a set of universal constitutive models to both fractures and rock matrices. Whether fractures or rock matrix are the dominators of mass transport depends on the connectivity of fracture networks. Minor changes in connectivity may trigger significant percolation threshold effects. [ABSTRACT FROM AUTHOR]

This paper mainly studies the recoverability performances for a coalbed methane (CBM) field located in the southeastern edge of the Ordos basin of China. Geological models are established, and drainage performances for four typical wells are described in detail. Single well simulations for the four wells are conducted to check accuracies of parameters and predict well drainage performances, and optimizations of well spaces are simulated to determine the most suitable well space. Results indicate that the reservoir parameters used in this study are quite accurate, and the well space of 350 × 300 m is most suitable in this area. Furthermore, the fifteen years’ field simulation under the well space of 350 × 300 m is conducted, which shows that the well number, average production and cumulative production are 1944, 7.01 × 10 8  m 3 /d and 105.22 × 10 8  m 3 , respectively. To validate the well space used in this study, analyses of recoverability and economic profit are conducted, both of which demonstrate that the well space of 350 × 300 m is most suitable in this area and can bring a stable drainage performance for a long time and get a high gas production. [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 objective of this study was to map and discriminate variations of vegetation net primary production (NPP) from the effects of precipitation variability and thereby identify the effects of grazing on NPP variations in the Xilingol Grassland. Satellite-based simulations of NPP collected over 14-year period and residuals method were used to normalize the effects of interannual precipitation on NPP. A fixed-size moving-window method was developed in this paper to quantify the annual grazing pressure (defined as grazing pressure index, GPI) on the regional scale, using vegetation cover images from 2001 to 2014. Temporal and spatial analysis methods were conducted to show patterns and trends of GPI and NPP residuals (NPP res ), and further to examine the effects of grazing pressure changes on variations of NPP res . Our results showed 80.7% of the study area experienced increasing NPP res and 18.5% with significantly increasing trends ( p  < 0.05). 76.7% of the study area showed decreasing grazing pressure, and 11.8% of areas experienced significantly decreasing trends ( p  < 0.05), with a small patches scattered distribution pattern. The negative correlations between NPP res and GPI were found in 94.6% of the study area, and 41.9% with significant correlation ( p  < 0.05); and long-term decreasing grazing pressure had positive impacts on vegetation NPP. They indicate grazing is a main driving factor of variations in vegetation NPP other than precipitation in Xilingol Grassland. The spatial patterns and temporal trends of NPP res , grazing pressure and responses of NPP res to grazing pressure changes varied among three main grassland types. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an alternative way to estimate volumetric vapour: liquid ratio of gaseous or light-petroleum inclusions without fluorescence using regularly-shaped inclusions to estimate volumetric vapour: liquid ratios through geometric methods. The method was applied to the inclusions from the rock samples of the Lower Triassic Feixianguan and Jialingjiang Formations, NE Sichuan (China). The trapping pressures of inclusion fluids were calculated by integrating PVT simulation software, volumetric liquid: vapour ratios determined by the proposed method and homogenization temperatures measured by microthermometry. Fluid densities and gas-oil ratios (GOR) were also estimated. The estimated trapping pressures and temperatures are slightly lower for the Jialingjiang formation (29.69–31.33 MPa, 93.5–105.2 °C) than for the Feixianguan Formation (31.02–34.38 MPa, 98–148 °C), and the trapping time of the inclusions in the Jialingjiang Formation and Feixianguan Formation were estimated at about 173–170 Ma and 178-168 Ma, respectively. The distribution of high pressures correlates with the presence of pyro-bitumen in the reservoir rocks, suggesting the migrated fluid is derived mainly from the secondary cracking of oil. The modeled fluid density and GOR correspond to a typical light oil or condensate, suggesting an origin for the trapped hydrocarbons as an intermediate product in this process. [ABSTRACT FROM AUTHOR]

The aim of this paper is to accurately predict the evolution of wheel profile wear and related vehicle dynamics for high-speed trains by considering the stochastic wheel/rail interactions, which experience quite variants with time and along long distant high-speed lines in China. These variants include the rail profiles, track geometries, track irregularities and interface characteristics associated with each segment of track. Mathematic normal distribution is introduced to rationally describe these stochastic parameters. The Archard wear model and FASTSIM algorithm are employed to determine the wear within a contact patch of the wheel, and a strategy based on the travel distance of wheel is used in the profile updating procedure. Referring to previous works, a nonlinear multibody vehicle system model is built and its accuracy was validated by lab tests. In the numerical simulation, three methods of stochastic matching of parameters in wheel/rail interactions are performed, including all constant parameters, only stochastic rail profiles, and both stochastic rail profiles and stochastic track parameters. Comparative studies show that there are good agreements in the wear evaluation of wheel profile between the simulated and measured results, as well as the behavior evaluation of vehicle dynamics in a total travel distance of 300,000 km. It is essential, therefore, to consider the stochastic matchings of parameters in the wheel/rail interaction for predicting the wheel profile wear and vehicle dynamics evolution of high-speed trains. [ABSTRACT FROM AUTHOR]

Based on sustainable development theory and the method of system dynamics and multi-agent simulation, the environment-economy-society relationship model of Liaohe River Basin is constructed by coupling the system dynamics model with the multi-agent model in the software-NetLogo. This paper selects the Qinghe, Fanhe and Puhe River of Liaohe River Basin which are located in Shenyang and Tieling City as the study boundary, then the overall situation of environment, economy and society development is analyzed. At the same time, in order to simulate and predict the overall operation of the model under different policies, three kinds of development scenarios are established by changing some key variables including pollution abatement investment, fixed assets investment and industrial waste water production of ten thousand yuan industrial output value. The results show that the development under different policies can be simulated and predicted by this model, which will provide support for macroeconomic regulation and control the sustainable development strategy of Liaohe River Basin. [ABSTRACT FROM AUTHOR]

In this paper, premature failure of the O-ring gaskets for the electric hydraulic system in a nuclear power plant in China was investigated. A series of macroscopic and microscopic analysis methods were conducted to identify the root causes of this unexpected failure, and the results showed that mismatch of the sizes between the O-ring gaskets and the groove of metal union was the primary reason, which gave rise to the permanent distortion and surface damage of the O-ring gaskets, and consequently leading to fracture under service conditions. Countermeasures were then proposed to prevent the recurrence of similar incidents, and were proved effective on site. [ABSTRACT FROM AUTHOR]

A method of constructing a double-deck subway station by combining two parallel shield tunnels and the cavern–pile method is presented. Taking the practical engineering of the Beijing subway as the background, numerical simulations were carried out to study enlarging construction. Mechanical and deformed performances for opening segments, important nodes, and main components of the station structure were investigated. Subsequently, a comparative analysis was performed to investigate the effects of side piles. Finally, an economic investigation was conducted to validate the practicability of the present method. This paper systematically demonstrates the applicability of the proposed method through a three-dimensional numerical simulation. The results show that it is safe and feasible to create a double-deck subway station by enlarging two parallel shield tunnels using the cavern–pile method. [ABSTRACT FROM AUTHOR]

Along with the increasing excavation of underground spaces, the mining industry has developed various techniques for refilling these voids. One of them is cemented paste backfill (CBP), coming from the mixing of tailings with water and a binder. These pastes are then transported to underground cavities through pipes and into voids, which they fill in a layering pattern. In this paper we explore the capabilities of a simplified thin-film model to describe the evolution of the paste shape within the stope. The mathematical difficulties are to include the yield stress behaviour of the paste and to deal with the walls in a consistent manner. We show the possible behaviours of the associated solutions to these problems, governed by 2 dimensionless parameters. Two regimes of filling are exhibited, when studying physical parameters typically used in CBP. Finally, we compare the simulations with physical experiments performed in a scaled lab setting using realistic tailings pastes from lead–zinc and nickel mines in North-West China. A good agreement is found between simulations and experiments. • A yield stress lubrication model is studied in the geometry of a closed stope. • The 2 governing dimensionless parameters are studied for typical values of CBP. • In this framework, we showed that two regimes of filling can exist. • Numerical simulations compare well with experiments using realistic tailings. [ABSTRACT FROM AUTHOR]

Abstract: This paper is based on dynamic optimization methodology to investigate the economic energy efficiency issues in developing countries. The paper introduces some definitions about energy efficiency both in economics and physics, and establishes a quantitative way for measuring the economic energy efficiency. The linkage between economic energy efficiency, energy consumption and other macroeconomic variables is demonstrated primarily. Using the methodology of dynamic optimization, a maximum problem of economic energy efficiency over time, which is subjected to the extended Solow growth model and instantaneous investment rate, is modelled. In this model, the energy consumption is set as a control variable and the capital is regarded as a state variable. The analytic solutions can be derived and the diagrammatic analysis provides saddle-point equilibrium. A numerical simulation based on China is also presented; meanwhile, the optimal paths of investment and energy consumption can be drawn. The dynamic optimization encourages governments in developing countries to pursue higher economic energy efficiency by controlling the energy consumption and regulating the investment state as it can conserve energy without influencing the achievement of steady state in terms of Solow model. If that, a sustainable development will be achieved. [Copyright &y& Elsevier]

Abstract: In China, both the mountainous areas and the number of people who live in mountain areas occupy a significant proportion. When production accidents or natural disasters happen, the residents in mountain areas should be evacuated and the evacuation is of obvious importance to public safety. But it is a pity that there are few studies on safety evacuation in rough terrain. The particularity of the complex terrain in mountain areas, however, makes it difficult to study pedestrian evacuation. In this paper, a three-dimensional surface cellular automata model is proposed to numerically simulate the real time dynamic evacuation of residents. The model takes into account topographic characteristics (the slope gradient) of the environment and the biomechanics characteristics (weight and leg extensor power) of the residents to calculate the walking speed. This paper only focuses on the influence of topography and the physiological parameters are defined as constants according to a statistical report. Velocity varies with the topography. In order to simulate the behavior of a crowd with varying movement velocities, and a numerical algorithm is used to determine the time step of iteration. By doing so, a numerical simulation can be conducted in a 3D surface CA model. Moreover, considering residents evacuation around a gas well in a mountain area as a case, a visualization system for a three-dimensional simulation of pedestrian evacuation is developed. In the simulation process, population behaviors of congestion, queuing and collision avoidance can be observed. The simulation results are explained reasonably. Therefore, the model presented in this paper can realize a 3D dynamic simulation of pedestrian evacuation vividly in complex terrain and predict the evacuation procedure and evacuation time required, which can supply some valuable information for emergency management. [Copyright &y& Elsevier]

This paper compares the performance of a 2.02 kWp off-grid residential solar photovoltaic (PV) power system using PVSYST simulation software for a household in Kunming, Yunnan province, China. The monthly available solar energy; missing energy; array, final, and reference yields, performance ratio; and array capture and system losses were analyzed for five solar tracking modes: fixed tilted plane, seasonal tilt adjustment, horizontal axis tracking, vertical axis tracking, and dual axis tracking. Although there were some similar aspects across the five systems, minimum available solar energy (2461 kWh/y) and maximum missing energy (134.68 kWh/y) were obtained using the fixed tilted plane system (tilt angle = 25°, azimuth angle = 0°), whereas maximum available solar energy (3081 kWh/y) and minimum missing energy (48.53 kWh/y) in October were obtained using the dual axis tracking system. Average monthly performance ratio was maximal for the fixed tilted plane system (0.689), and minimal for the dual axis tracking system (0.596). [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]

Abstract: With attractive advantages of high efficiency, energy saving and environmental friendliness, the ground source heat pump (GSHP) system has been used widely in China in recent years. This paper summarizes the analytical solution, numerical solution and experimental investigation of the heat transfer of the ground heat exchanger (GHE), analyzes the simulation model and long-term operation performance of the GSHP system, and introduces the lastest hybrid ground source heat pump (HGSHP) system. In addition, this paper discusses and summarizes the shortages and imperfects of the current research on the simulation of the GSHP system and gives some recommendations for future work. [Copyright &y& Elsevier]

Shale reservoirs have attracted increasing attention in recent years as a new and promising geological repository for carbon dioxide (CO 2 ) storage. However, their long-term storage mechanism is unclear and the interactions between CO 2 adsorption to shale and the CO 2 -water-rock reactions have not been investigated. A 2-D simplified reactive transport model is developed in this paper based on the properties of a shale reservoir in the Ordos basin in China which has been identified as a promising location for shale gas production and CO 2 storage. The model is used to study the CO 2 -water-rock reactions coupled with gas adsorption and to identify the long-term trapping mechanisms of CO 2 in shale gas. Results show that in short (several decades) to middle term (hundreds of years) CO 2 storage in a shale reservoir, > 60% CO 2 is trapped in the supercritical and adsorbed phases, but in the long term (thousands of years), mineral trapping gradually plays a dominant role among other storage mechanisms. The displacement of CH 4 with CO 2 during injection is also analyzed. Results show that this process can be divided into two stages: the pre-displacement stage during which the adsorbed concentrations of both CH 4 and CO 2 increase due to pressure build-up, but due to low concentration of CO 2 displacement does not occur at this stage; and the displacement stage during which the CO 2 concentration is high enough to displace the CH 4 from the host rock. Also, higher pressure facilitates the displacement of CH 4 by CO 2 in this stage. Study of the interaction between gas adsorption and CO 2 -water-rock reactions shows that by buffering the reservoir pressure during CO 2 injection into the subsurface, gas adsorption can impact the solubility trapping process so as to interfere with the CO 2 -water-rock reactions. Furthermore, this interference is intensified with reduction in CO 2 concentration in the reservoir over time. Sensitivity analysis indicates that variations in the CO 2 adsorption isotherm, abundance of smectite and chlorite, reaction rate and reactive surface area of smectite can significantly affect the CO 2 storage by different trapping mechanisms. The high CO 2 adsorption capacity of shale is very beneficial for CO 2 injection into a shale reservoir; the amount of adsorbed CO 2 is proportional to the CO 2 adsorption isotherm, while CO 2 in other phases (gas/supercritical phase, dissolved phase and mineral phase) is inversely related to the CO 2 adsorption isotherm. Smectite and chlorite are the key minerals that influence the CO 2 -water-rock reactions in Yanchang shale. [ABSTRACT FROM AUTHOR]

• A data-assimilation method has been proposed for the burnup distribution. • The three-dimensional variational algorithm and artificial neutral network algorithm were applied. • The data-assimilation method has been applied to PWR operated in China. In this paper, a data-assimilation method has been proposed and applied for the burnup distribution of PWR. The burnup distribution is significant for the safety and economy of the reactor, as it is essential for the fuel-reloading design and optimization. Due to the fact that the burnup distribution cannot be measured directly during the reactor operation, the numerical simulation is widely applied in reactor engineering. However, there definitely exist differences between the numerical simulation and the actual core due to some unavoidable factors, such as component manufacturing deviation, uneven flow distribution and so on. These differences would induce the errors to the simulation values of power distributions and hence to the burnup distributions. Therefore, a data-assimilation method for the burnup distribution has been proposed, aiming at reducing the burnup-distribution errors with application of the power-distribution measurements. In our research, the three-dimensional variational (3DVAR) algorithm was applied for burnup-distribution calibration and the artificial neutral network (ANN) algorithm was applied to establish the complex relations between burnup distribution and power distribution. As engineering verification, the proposed data-assimilation method has been applied to the CNP1000 PWR operated in China. The numerical results indicated that the burnup-distribution errors can be reduced notably, as the maximum value of relative errors for power distribution can be reduced from 9.53% to 5.11%. [ABSTRACT FROM AUTHOR]

Abstract: This paper provides an in-depth illustration of the shallow tunnelling method (STM) used for tunnelling in shallowly buried soft ground. Limited arching effect and limited ground strength mobilization are the two mechanical characteristics of the STM. The stability of the cutting face and the dry tunnelling condition are the two preconditions that should be satisfied for the STM. Some “necessary” auxiliary methods mainly served to guarantee these two preconditions are highlighted. Five principles, namely proper auxiliary methods, sequential excavation with short advance length, rigid support with quick installation, short ring closure time and systematic deformation monitoring, which are required to follow when using the STM are summarized. The state-of-art of the STM is classified into five different construction approaches according to tunnelling sequences, which are adopted in the construction of the nine subway stations in Beijing. The tunnelling procedures, support measures and settlement characteristics associated with excavation are demonstrated. Statistical analyses of the settlement data of 342 ground surface monitoring points above these nine stations are performed to illustrate the ground deformation characteristics of the STM. Numerical simulations are also employed to study the ground deformation characteristics of different construction approaches under the same geological conditions. This paper systematically demonstrates the applicability of STM in theory and practice. It is helpful in updating the database of the world tunnel projects and serving as a practical reference for future similar projects. [Copyright &y& Elsevier]

Abstract: The effective control of gas emissions from longwall faces and gob areas in the coal mining industry in China has become increasingly important. Drilling underground gas drainage holes from a surface is an effective way to release gas. Once a coal seam is extracted, the rock strata above a gob subside and move, after which the gas drainage borehole and casing become damaged due to state changes in the rock. In this paper, we perform a deformation and failure analysis of a surface venthole casing using the numerical simulation method. The numerical investigation is carried out on the casing under compression, tension, and shear conditions. The general factors that affect casing failure are discussed, and basic failure modes are summarized. The experimental casing of the surface venthole at Cheng Zhuang Colliery (CZC) is also analyzed by numerical simulation. The actual deformation and failure of the casing are examined using on-site monitoring data, to which the numerical simulation results are then compared. We deduce that the tensile and shear failures occur at the lower part of the casing or at the bedding plane separation. Monitoring must be focused on these areas, and protective measures should be used. The numerical simulation model is simplified given various restrictions. The integration of numerical simulation and monitoring technology can serve as an efficient method for the quantitative analysis of failure on surface venthole casings. The research concepts presented in this paper and the rules deduced are useful references. [Copyright &y& Elsevier]

Abstract: This paper introduces the development of a dynamic parallel algorithm for conducting hydrological model simulations. This new algorithm consists of a river network decomposition method and an enhanced master–slave paradigm. The decomposition method is used to divide a basin river network into a large number of subbasins, and the enhanced master–slave paradigm is adopted to realize the function of this new dynamic basin decomposition method through using the Message-Passing Interface (MPI) and C++ language. This new algorithm aims to balance computation load and then to achieve a higher speedup and efficiency of parallel computing in hydrological simulation for the river basins which are delineated by high-resolution drainage networks. This paper uses a modified binary-tree codification method developed by to code drainage networks, and the basin width function to estimate the possible maximum parallel speedup and the associated efficiency. As a case study, with a hydrological model, the Digital Yellow River Model, this new dynamic parallel algorithm is applied to the Chabagou basin in northern China. The application results reveal that the new algorithm is efficient in the dynamic dispatching of simulation tasks to computing processes, and that the parallel speedup and efficiency are comparable with the estimations made by using the basin width function. [Copyright &y& Elsevier]

Abstract: This paper presents a nonlinear piecewise smooth dynamical system of the trajectory of deviated wells according to engineering background. An optimal control model is established and the necessary conditions for optimality are proved via maximum principle. The optimal control problem is solved by a revised Hooke–Jeeves algorithm. The uniform design technique has been incorporated into the revised Hooke–Jeeves algorithm to handle the multimodal function. Computer simulation is used for this paper, and the numerical example illustrates the validity and efficiency of the algorithm. The procedure demonstrates its advantages in practical applications in Liaohe Oil Field. [Copyright &y& Elsevier]

The coal roadway heading using a blasting method is very common in China. However, the coal dust produced by blasting is the most serious problem in a roadway of coal mine. The gas–solid two-phase flow regularity for blasting heading face is the key scientific issue for dust control. In this paper, a real blasting heading face in China was taken as the physical model and a method coupling a direct simulation Monte Carlo (DSMC) scheme with a CFD software was adopted to study the properties of dust particles (0.1–100 μm in diameter) in the flow field of a roadway after blasting. The results show that dust group produced from the heading face is jetted into the roadway under the shock wave after blasting, and is diluted from its back-end to the front-end by the airflow from the pressing pipe arranged around the heading face, then dust concentration shows an overall gradual decrease, and finally the respirable dust particles exhibit an alternant thin dense phase distribution in the roadway, whereas other dust particles (>5 μm in diameter) spread at the bottom of the roadway and form dust retention. The dust concentration in the front-end of the roadway around the heading face is always higher than that in other zones due to the existence of vortex region. The respirable dust concentration is slightly greater than the standard of air quality in the beginning, and quickly reaches the standard. But the total dust concentration always does not meet the standard of air quality in general. The simulation results are also verified by the field data. The research results are helpful for providing more suitable guidance for the dust control. [ABSTRACT FROM AUTHOR]

The renewable energy power generation (REPG) in China has experienced tremendous growth in the last decade. To understand this rapid growth, it is necessary to explore how Chinese government triggers the remarkable development of the industry. This paper offers a systematic analysis of the incentive policy system for REPG in China, covering wind power, solar photovoltaic, small hydropower (single-unit power generation capacity less than 50 MW), biomass power and geothermal power. The incentive system contains laws, regulations, policies and industrial plans issued during the 11th and 12th “Five-year Plan” periods (2006–2015). Four major incentive strategies of the Chinese government are identified: research and development incentives, fiscal and tax incentives, grid-connection and tariff incentives, and market development incentives. The results show these incentive methods have played a significant role in promoting the development of REPG in China, but still there are some problems associated with them. International comparisons of the incentive policies with those of Denmark, Germany and US, as well as the strategies to further improve the Chinese incentive approaches are discussed. This comprehensive analysis of China's incentive policy system for REPG helps to understand China's experience in promoting renewable energy, contributing to better decision-making in policy. [ABSTRACT FROM AUTHOR]

A micro-pressure wave (MPW) is generated when a train enters a tunnel at high speed, which causes a strong impact on the environment around the tunnel. The increased lining used to repair damage in high-speed railway tunnels changes cross-sections and has a strong influence on the MPW at the tunnel exit. In this paper, the methods of full-scale measurement, numerical simulation and moving-model experiments are used to study the MPW generated in a tunnel whose lining is increased. The rules governing the effect of increased linings on MPWs are obtained, which can be used as a reference for the Tunnel Damage Regulation Project in China. [ABSTRACT FROM AUTHOR]

This paper aims to test the ability of the WRF-Chem model to simulate sand storms in Northwest China and improve the simulation results by introducing remote sensing soil moisture data into WRF-Chem. We conducted sensitivity tests, including parameterization scheme tests and soil moisture tests using WRF-Chem. By comparing various combinations of parameterization schemes, which have considerable impacts on sand emissions, the most suitable parameterization scheme for WRF-Chem to simulate sand storms in Northwest China was selected for establishing models in future research. Based on the optimal combination of parameterization schemes, the sensitivity of sand emissions to soil moisture was tested, indicating that soil moisture has a substantial influence on sand emissions and revealing a nonlinear relationship between sand emissions and soil moisture. Although sand simulations are sensitive to soil moisture, the sand emission volume does not always increase with decreasing soil moisture content. Moreover, the soil moisture content simulated by WRF-Chem is quite different from that observed by satellites. Therefore, we selected ten sand storms that occurred in Northwest China in 2009–2018, including weak, moderate and strong sand storms, to explore the responses of sand storms of different intensities to soil moisture. Some experiments were conducted in two scenarios: scenario A was simulated only by WRF-Chem, and scenario B was designed by replacing the initial soil moisture field in WRF-Chem with soil moisture satellite data from AMSR2 and AMSR-E. Comparing the simulation results with in-situ ground-based and satellite-based measurements indicates that WRF-Chem can capture strong sand storms and some moderate sand storms, but the ability to simulate weak sand storms needs to be greatly improved. After introducing remote sensing soil moisture data into WRF-Chem, the simulation of sand emissions becomes more accurate, substantially improving the simulation results. Among the ten simulated sand storms, the AOD (aerosol optical depth) and PM10 simulation accuracies are improved for five and seven sand storms, respectively. After this improvement, the AOD correlation coefficient can reach 0.63, and the PM10 correlation coefficient can reach 0.60. • The paper screened out the best parameterization scheme of sand storm simulation that is suitable for northwestern China. • Improved the simulation results of the WRF-Chem model using soil moisture remote sensing data. • WRF-Chem can better capture strong and some moderate sand storms, but need to improve weak sand storm simulation ability. [ABSTRACT FROM AUTHOR]

Wind-driven rain (WDR) has significantly unfavorable effects on the performance and durability of the enclosure systems of low-rise buildings. Therefore, a field measurement facility for the WDR on a gable-roofed low-rise building with overhang has been established and implemented in a typhoon-prone region of China. This paper presents and analyzes the field measurements of the WDR on the facades of the full-scale building during a typhoon in 2018. In addition, numerical simulations of the WDR on the instrumented building are performed using the Eulerian Multiphase model and validated based on the field measured WDR results. Then, a detailed parametric study of numerical simulation is carried out to examine the influences of roof overhang, wind speed, wind direction and horizontal rainfall intensity on the WDR amounts on the building facades. Next, the WDR on the low-rise building during a super typhoon are numerically reproduced and investigated. The measurement techniques and numerical simulation methodologies, analyzed results and conclusions presented in this paper would be useful to understand and evaluate the WDR on building facades so as to improve the serviceability of low-rise building envelopes. • Establish measurement facility of wind driven rain (WDR) on a low-rise building. • Analyze measurements of WDR on the full-scale building during a typhoon. • Verify the numerical simulation results based on the field measurements. • Examine effects of key parameters on WDR by a detailed parametric study. • Further investigate WDR on the building under extreme weather condition. [ABSTRACT FROM AUTHOR]

Abstract: The jacket platforms are strong enough to resist extreme ice forces in Bohai Sea, China. However, ice-induced vibration acceleration has been observed and caused non-structure failure such as human discomfort and gas leakage due to flange loosing of pipes in winters. As a method of reducing ice-induced vibrations, this paper proposed an isolation cone system composed of cones, springs and dampers, which is located on the pile of jacket platforms at sea level. In order to examine the ice-induced vibration acceleration reduction effectiveness of the isolation cone system for jacket platforms, a numerical simulation is conducted to JZ20-2MUQ jacket platform as an example. It is shown from the numerical study and observed data that the isolation cone system is effective in reducing the ice-induced vibration acceleration responses and avoiding non-structure failure of jacket platform structures. [Copyright &y& Elsevier]

Bed entrainment plays an important role in the run-out process of a flow-like landslide. A limited number of studies have investigated the influence of entraining loose materials on the mechanical properties of a landslide, and some of them have considered bed entrainment either by mechanical or empirical methods. In this paper, a modified finite difference model was used to analyze the propagation process of a typical flow-like landslide with bed entrainment that occurred in the Jingyang loess tableland, China. In this model, the mechanical parameters of the sliding mass were modified according to the local entrainment depth. Triaxial Consolidated Undrained (CU) tests and ring shear tests were conducted to obtain the mechanical parameters needed in the numerical simulation. The triaxial CU tests were conducted on three intact loess samples taken at the back scarp of the landslide, and the ring tests were conducted on gravelly sand samples taken from the first terrace of the Jinghe River, which includes the landslide deposit. The results show that both the simulated run-out distance and final covering area agreed well with the field data. The modified model revealed the propagation process of this landslide. A major contribution of this study is that entraining the saturated gravelly sand contributed to the flow-like movement of the landslide. The case study investigated here is helpful for better an understanding of the flow-like transformation mechanism. In addition, the numerical model adopted in this paper can be effectively used to assess or predict the propagation processes of similar landslides. • The propagation process of a loess flow-like landslide with bed entrainment is analyzed. • The significant shear strength loss of loess contributes to the rapid acceleration of this landslide. • Entraining saturated terrace material contributes to the flow-like transformation of this landslide. [ABSTRACT FROM AUTHOR]

Abstract: Grey theory is one approach that can be used to construct a model with limited samples to provide better forecasting advantage for short-term problems. Generally, the GM (1,1) and Discrete GM (1,1) models are two typical grey forecasting models in grey theory. However, there are two shortcomings in the above grey models respectively, i.e., the homogeneous-exponent simulative deviation in GM (1,1) model, and the unequal conversion between the original and white equations in DGM (1,1) model. In this paper, we firstly propose a novel Generalized GM (1,1) model termed GGM (1,1) model, based on GM (1,1) and DGM (1,1) models, to overcome the above shortcomings. Then, we detailedly study four important properties in this new grey model. Four estimative approaches of stepwise ratio in GGM (1,1) model context is also covered. In the end, we simulate and forecast the fuel production in China during the period 2003–2010 using three GM (1,1) models. The empirical results show that GGM (1,1) model has higher simulative and predictive accuracy than GM (1,1) and DGM (1,1) models. This work contributes significantly to improve grey forecasting theory and proposes a optimized GM (1,1) model. [Copyright &y& Elsevier]

Abstract: Double curved arch bridges have played an important role in the history of bridge construction in China. The strengthening or retrofitting of this type of bridge has attracted a great deal of research attention in the Chinese bridge engineering community. In this paper, a novel strengthening method, i.e. the extrados section augmentation strengthening method (ESASM), has been reported. Firstly, the rationale behind this new method and the changes in internal forces after strengthening have been studied in details. A numerical optimization analysis was then performed to derive a strengthening design solution based on these results. Secondly, a trial use of this novel strengthening method in a double curved arch bridge has been reported. A numerical simulation was carried out to analyze the internal forces in the bridge both before and after it was strengthened. Results show that internal forces have been favourably redistributed after the bridge has been strengthened by using ESASM. Lastly, the adopted construction method and the strengthening effect for that project were described. [Copyright &y& Elsevier]

Abstract: Research on earthquake-induced collapse simulation has a great practical significance for super-tall buildings. Although mega-braced frame-core tube buildings are one of the common high-rise structural systems in high seismic intensity regions, the failure mode and collapse mechanism of such a building under earthquake events are rarely studied. This paper thus aims to investigate the collapse behavior of a super-tall mega-braced frame-core tube building (H =550m) to be built in China in the high risk seismic zone with the maximum spectral acceleration of 0.9g (g represents the gravity acceleration). A finite element (FE) model of this building is constructed based on the fiber-beam and multi-layer shell models. The dynamic characteristics of the building are analyzed and the earthquake-induced collapse simulation is performed. Finally, the failure mode and mechanism of earthquake-induced collapse are discussed in some detail. This study will serve as a reference for the collapse-resistance design of super-tall buildings of similar type. [Copyright &y& Elsevier]

Abstract: This paper presents the pre-experiment plan and prediction of the first stage of vacuum laser acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a proof-of-principle to support our previously posted novel VLA theory. Simulations show that based on ATF''s current experimental conditions the electron beam with initial energy of 15MeV can get net energy gain from an intense CO2 laser beam. The difference in electron beam energy spread is observable by the ATF beam line diagnostics system. Further, this energy spread expansion effect increases along with an increase in laser intensity. The proposal has been approved by the ATF committee and the experiment will be our next project. [Copyright &y& Elsevier]

Abstract: This paper develops an overall methodology for investigating the thermal and power behaviors of semi-transparent single-glazed photovoltaic window for office buildings in Hong Kong. In order to estimate its overall energy performance, this study is conducted in terms of total heat gain, output power and daylight illuminance. Three simulation models are established, including one-dimensional transient heat transfer model, power generation model and indoor daylight illuminance model. A typical office room reference is chosen as case study, and the weather data from 2003 to 2007 from the Hong Kong Observatory are used as the simulation inputs. By incorporating the simulation results, the overall energy performance can be evaluated in terms of electricity benefits corresponding to five orientations of the studied typical office. The priority of office orientation considering overall energy performance is: south-east, south, east, south-west and west. The findings show that thermal performance is the primary consideration of energy saving in the entire system whereas electricity consumption of artificial lighting is the secondary one. The overall annual electricity benefits are about 900 kWh and 1300 kWh for water-cooled and air-cooled air-conditioning systems respectively. The application of semi-transparent PV glazed window can not only produce clean energy, but also reduce building energy use by reducing the cooling load and electrical lighting requirements, which definitely benefits our environmental and economic aspects. [Copyright &y& Elsevier]

Abstract: Student dormitories are both living and resting areas for students in their spare time. There are many small rooms in the dormitories. And the students are distributed densely in the dormitories. High occupant density is the main characteristic of student dormitories. Once there is an accident, such as fire or earthquake, the losses will be cruel. Computer evacuation models developed overseas are commonly applied in working out safety management schemes. The average minimum widths of corridor and exit are the two key parameters affecting the evacuation for the dormitory. The effect of varying these two parameters will be studied in this paper by taking a dormitory in our university as an example. Evacuation performance is predicted with the software FDS + Evac. The default values in the software are used and adjusted through a field survey. The effect of varying either of the two parameters is discussed. It is found that the simulated results agree well with the experimental results. From our study it seems that the evacuation time is not in proportion to the evacuation distance. And we also named a phenomenon of “the closer is not the faster”. For the building researched in this article, a corridor width of 3 m is the most appropriate. And the suitable exit width of the dormitory for evacuation is about 2.5 to 3 m. The number of people has great influence on the walking speed of people. The purpose of this study is to optimize the building, and to make the building in favor of personnel evacuation. Then the damage could be minimized. [Copyright &y& Elsevier]

Abstract: A novel method for dynamic risk assessment of oil spill accidents based on numerical simulation was presented in this paper. The dynamic risk assessment model was developed consisting of a comprehensive list of caused consequences like environmental damage, asset loss, health impact and social effect as well as emergency actions preventing these losses. Contributing events in the Mater Logic Diagram (MLD) of the dynamic risk assessment model were valued based on the simulated evolvement of oil contaminants under spill scenario on quasi-static fluid, which was obtained by coupling an oil spill model with hydrodynamic module in Jialing river of Three Gorges Reservoir in China after the impoundment of the reservoir to 175m water level in 2010. Calculated result of dynamic risk as grade IV indicated that the assessed oil spill was not as catastrophic as we thought because of the slow transport of oil fractions on water surface and absence of dispersed oil in water body due to the quasi-static fluid, very gentle wind and effective emergency actions, as well as by the reason that rare agriculture or industrial crops exist in spill adjacent area. [Copyright &y& Elsevier]

Abstract: High energy gas fracturing (HEGF) technique has been one of central stimulating measures to enhance oil recovery in low permeability reservoirs. But, in recently few years, some serious CO poisoning accidents took place in oilfields here in China. It is very important to reveal the dynamic mechanisms of carbon monoxide flow and diffusion to operating safety during high energy gas fracturing. In this paper, some dynamic mechanisms of carbon monoxide CO flowing inside a oil wellbore and diffusion on the top of the well during high energy gas fracturing were studied with fluid/gas hydrodynamics. The CO flow model within a wellbore and the diffusion model in air were established. The key factors affecting CO flow and diffusion such as wellbore pressure, gas–oil ratio, wind speed, leakage speed, air-permanence were inspected with mathematical simulation. It will be of significance to provide an important guidance for monitoring and preventing CO poisoning accidents during high energy gas fracturing. [Copyright &y& Elsevier]

Abstract: For the caving and sliding control of roadways with large cross-section, thick mudstone roof and abutment pressure influence, the cable truss system is proposed and its support mechanism is thoroughly analyzed in this paper. Furthermore, according to the geometric size and ground pressure conditions on field coal roadways Nos. 101, 102 and 103 in Xinyuan Coal Mine, three types of cable truss support systems are designed for obtaining the optimum cable truss support system. Then the corresponding parameters for each support design are determined by use of the numerical simulation method, and three kinds of support systems are put into practice. The field observation results show that roof should be effectively controlled by the normal cable truss structure consisting of two long cables and one connector, and both coal sides can be protected by the simplified cable truss structure composed of two short cables and one channel bar. Finally, the optimal support system is gotten which is much better than the other two support designs in rock deformation control effect and economic profits. [Copyright &y& Elsevier]

Abstract: This paper investigates the efficiency and equity of morning peak ramp control schemes in a freeway corridor with limited capacity. In terms of efficiency, both short-run and long-run optimal ramp control schemes are obtained by minimizing the total travel cost and maximizing the total social benefit along the corridor. It is found that for a short-run optimum with inelastic demand, the morning peak period is of the same duration for different on-ramp locations. But for a long-run optimum with elastic demand, the peak duration for various on-ramps increases with the local capacity elasticity of demand. In terms of equity, two measures are defined from a demand-based viewpoint and a space-based viewpoint. It is shown that the short-run optimal ramp control scheme is perfectly fair from a demand-based equity viewpoint. Consequently, two typical ramp control schemes—a perfect demand-based equity scheme and a perfect space-based equity scheme—are introduced and compared with the long-run optimal ramp control scheme in terms of efficiency and equity. Numerical simulations using survey data from China suggest that the perfect demand-based equity scheme attains an economic welfare level that is very close to the optimal one and the conflict between efficiency and equity diminishes as demand becomes less elastic. [Copyright &y& Elsevier]

Abstract: We abstract bus transport networks (BTNs) to complex networks using the Space P approach. First, we select three actual BTNs in three major cities in China, namely, Beijing, Shanghai and Hangzhou. Using the SIS model, we simulate and study the epidemic spreading in the three BTNs. We obtain the density of infected vertices varying with time and the stationary density of infected vertices varying with infection rate. Second, we simulate and study the epidemic spreading in a recently introduced BTN evolution model, the network properties of which correspond well with those of actual BTNs. Third, we use mean-field theory to analyze the epidemic dynamics behavior of the BTN evolution model and obtain the theoretical epidemic threshold of this model. The theoretical value agrees well with the simulation results. Based on the work in this paper, we provide the following possible forecasts for epidemic dynamics in actual BTNs. An actual BTN should have a finite positive epidemic threshold. If the effective infection rate is above this threshold, the epidemic spread in the network and the density of infected vertices finally stabilizes in a balanced state. Below this threshold, the number of infected vertices decays exponentially fast and the epidemic cannot spread on a large scale. [Copyright &y& Elsevier]