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The recovery of unconventional gas fields especially the shale gas is of great significance to clean energy supply. High productivity of shale gas is attributed to the large-scale hydraulic fracturing with high operating pressure (80-100MPa) and discharging rate (14-18m3/min). More high-horsepower fracturing vehicles driven by diesel engines result in higher CAPEX. The low operation efficiency and unexpected maintenance negatively affected the economics performance of operators due to unacceptable OPEX. The fully electric-powered hydraulic fracturing solution was proposed as the alternative to the diesel-engine fracturing vehicles in this article. The skid-based electric pumping units were newly developed with advantages of high power density (6000HP per unit), Variable Frequency Drive (VFD) modules integration, fuel cost saving, low maintenance expenditure and eco-friendly operation. The field application was conducted in one pad of N209 in shale gas field, Sichuan, China. The electric-powered system, consisting of pumping units and blenders with other facilities, was deployed on the operation site. One large-capacity electric power grid (35kV and 30000kVA) was constructed for both drilling and massive multistage fracturing. The operation team successfully performed all hydraulic fracturing jobs as required with 7.4×105 kWh of total power consumption. The system functioned reliably without large faults occurred. The electric-powered solution was comprehensively evaluated and compared to the diesel-engine fracturing solution in terms of CAPEX, operational efficiency, power consumption, maintenance and fleet crew cost. The novelty of the technology is the fully electric-powered hydraulic fracturing system with large-capacity electric power grid. It is concluded from the field application that the electric-powered fracturing technology is qualified for unconventional reservoirs development.

With the increasing improvement of people's living standards, air conditioning as a major energy user has become an important factor affecting household electricity consumption plans. This study first identifies a strong correlation between temperature and air conditioning electricity consumption. Then, a regional air conditioning energy consumption model is developed based on regression analysis to meet the needs of household electricity management systems. First, to obtain a more intuitive relationship between temperature and electricity consumption, an improved k-means clustering algorithm is used to classify regional air conditioning energy consumption data. Second, based on four types of curves obtained by clustering, regression methods are used to propose a multi-class regional air conditioning energy consumption model which can support accurate quantitative analysis. Finally, the validity and accuracy of the proposed model are demonstrated by regional prediction experiments. The results can provide references for scientific electricity consumption planning of households.

An Al2O3/Y3Al5O12 eutectic ceramic was prepared with a c-axis sapphire seed by an optical floating zone furnace. The crystallographic relationships in the initial and the steady growth sections of the as-grown eutectic ceramic were investigated by electron backscattering diffraction and transmission electron microscopy. The corresponding results were: {101}Y3Al5O12 || {112¯0}Al2O3 and {21¯1}Y3Al5O12 || {0001}Al2O3, respectively. The steady orientation of the latter one shows smaller planar disregistry. Interfacial strain played the decisive role in affecting the solidification behavior of the Al2O3/Y3Al5O12 eutectic ceramic. The stability of interfaces with minimum interfacial strain and better ionic charge balance in irregular microstructure prevail upon the constraint of the seed. These results might cast light for the interfacial design of the Al2O3/Y3Al5O12 binary eutectic ceramic. This article is protected by copyright. All rights reserved.

Introduction As the world's fastest growing “addiction”, Internet addiction is still controversial. The present study aimed to examine the potential personality predictors of Internet addicts. Methods Eight hundred and sixty-eight students were tested using the Eysenck Personality Questionnaire after they had just entered university. Two years later, 49 were found to be addicted to the Internet as defined by high Internet addiction test scores. Comparisons of means and logistic regression analysis were used to explore their relationship. Results Students addicted to the Internet showed higher Neuroticism/Stability scores, higher Psychoticism/Socialization scores, and lower Lie scores than their normal peers before their addiction. Regression results showed that Internet addiction was accounted by three independent variables: Neuroticism/Stability, Psychoticism/Socialization, and Lie. Conclusion These results suggest that the risk personality traits of Internet addiction include neuroticism, psychoticism, and immaturity.

Cracking is a major distress in steel bridge deck pavements. To determine the critical cracking zone, a numerical multiscale structural analysis was proposed and performed on the basis of a case study. First, a whole bridge model was analyzed, which revealed that the critical segment under critical load combination was one-fourth of the bridge span. Second, the critical segment was modeled using the finite mixed element method, and the critical local plate was determined. Third, using a submodel technique, the critical orthotropic steel plate with pavement was analyzed. The constructed model was then updated through an equivalent impact factor obtained from a numerical model analysis that considered vehicle–pavement interaction. From such multiscale model analysis, the crack distribution law of steel deck pavements was determined. Comparison of the analysis results from a traditional model with the multiscale model revealed the non-negligible effects of bridge structure and pavement evenness. Find...

To describe the crack development of epoxy asphalt concrete (EAC) from the three-dimensional (3-D) scale perspective, a 3-D heterogeneous digital sample independent of laboratory is reconstructed. A bilinear cohesive-softening model is implemented into the discrete element method (DEM) framework to simulate the crack behavior. The corresponding micromechanical models describing the interaction of micro-scale components of the virtual specimen are assigned. The simulation results of a single-edge notched beam test are shown to compare favorably with the experimental results and accurately capture the distributions of fracture zone and stress within the model. The developed 3-D visualization modeling technique is capable of simulating the initiation and propagation of cracks during the bending fracture of EAC. Also the 3-D user-defined microstructural DEM fracture model also has the potential ability to help understand various fracture mechanisms and shows a realistic cracking process of quasi-brittle materials such as EAC.

As the world's fastest growing "addiction", Internet addiction is still controversial. The present study aimed to examine the potential personality predictors of Internet addicts.Eight hundred and sixty-eight students were tested using the Eysenck Personality Questionnaire after they had just entered university. Two years later, 49 were found to be addicted to the Internet as defined by high Internet addiction test scores. Comparisons of means and logistic regression analysis were used to explore their relationship.Students addicted to the Internet showed higher Neuroticism/Stability scores, higher Psychoticism/Socialization scores, and lower Lie scores than their normal peers before their addiction. Regression results showed that Internet addiction was accounted by three independent variables: Neuroticism/Stability, Psychoticism/Socialization, and Lie.These results suggest that the risk personality traits of Internet addiction include neuroticism, psychoticism, and immaturity.

Cracking in epoxy asphalt concrete (EAC) used for a steel bridge wearing course has always been a major cause of structural and functional deterioration of this material, particularly in cold climate. Therefore, it is important to understand the complex fracture behavior of this heterogeneous mixture, which is composed of irregularly shaped and randomly distributed aggregates surrounded by asphalt mastics. A three-dimensional (3D) fracture model independent of laboratory, based on the discrete element method (DEM), is reconstructed using a randomly generating algorithm to investigate the fracture behavior. A bilinear cohesive-softening model is implemented into the DEM framework to simulate the crack initiation and propagation in EAC. Several experimental tests are performed to obtain input parameters of materials for numerical models. The simulation results of a single-edge notched beam test agree well with experimental results and accurately capture the stress distribution and development of fracture zone. The modeling technique herein provides insight into the progressive cracking process; 3D visualization of crack trajectories also demonstrates the influence of heterogeneity on crack path. The 3D user-defined microstructural DEM fracture model is capable of giving a realistic cracking process of quasi-brittle materials such as EAC and can help us better understand various fracture mechanisms through numerical simulations.