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The closure fracture phenomenon increases the complexity of well testing and reduces the accuracy of productivity forecasts when tight oil reservoirs are exploited. However, most existing productivity models tend to ignore this. Therefore, a productivity prediction model for multi-fractured horizontal wells in tight oil reservoirs considering fracture closure has been developed by considering the stress sensitivity in the formation and combining the physical parameters of actual production. The model is solved by the Laplace transform, perturbation transform, Pedrosa transform, and Stehfest numerical inversion. Drawing productivity impact curves and discussing productivity influence factors based on the model results from this study show that the model is reasonable. In the actual production process, the hydraulic fracture parameter values are not as high as possible, and they have a reasonable range of values. The fracture closure pressure has a significant impact on the production of tight oil reservoirs. The higher the fracture closure pressure is, the greater the fracture conductivity decreases sharply, and the larger the proppant elastic modulus is, the stronger the fracture conductivity. The influence of fracture conductivity on the production in tight oil reservoirs has an obvious point, and when the value is less than the point, the production effect is good. Improved production can be achieved by balancing the relationship between fracture parameters. The findings of this study can help to better understand the influence of fracture parameters on productivity and contribute to increasing well production and improved development of tight oil reservoirs.

Cities are faced with various kinds of pollution issues in the process of economic development, among which industrial pollution has become the most terrifying environmental issue in recent years, so that industrial pollution control should be emphasized. Finding out the key factors influencing industrial pollutant emissions is the basis of taking corresponding measures. Previous studies only focused on one pollutant without a comparative analysis of the contribution of influencing factors to multiple pollutants. Therefore, this study aims to identify the key influencing factors of industrial pollutants in Nanjing, Suzhou, Xuzhou, and Taizhou in Jiangsu Province during the years 2008-2018 by using the logarithmic mean Divisia index (LMDI) method. The results from decomposition indicate the following. (1) Emission intensity (EI) and energy efficiency (EE) are negative factors for decreasing industrial pollutant emissions, while the economic output (EO) and population (P) are positive factors for increasing industrial pollutant emissions. (2) Emission intensity has the most significant influence to industrial wastewater in decreasing emissions; energy efficiency makes the biggest contribution to industrial solid waste in decreasing emissions, economic output and population contribute the most to industrial solid waste in increasing emissions. (3) Nanjing has the highest contribution rate of emission intensity and population, and the contribution rate of energy efficiency and economic output to Taizhou is the highest. Identifying the key driving factors of different pollutants can serve as evidence and guidance for urban environmental governance, therefore reducing emissions ulteriorly, and achieving sustainable development.

Consumer uncertainty about product valuation is a significant economic issue in online retailing. In many markets, even though the product quality information is completely disclosed, consumers may still remain unsure about their valuation-for-quality. This paper investigates the effects of consumers’ uncertain valuation-for-quality on a platform’s and a firm’s profits under commonly used wholesale price contract and consignment contract in a distribution channel. Our analysis reveals that regardless of the contract types, when the product quality is relatively low, both the platform and the firm benefit from a higher degree of informativeness of information; when the product quality is relatively high, however, the profits of both the platform and the firm show nonmonotonicity with respect to the informativeness degree (namely, first decrease then increase), which is driven by the joint effects of the value-enhancement effect and the segmentation effect incurred from the consumers’ uncertain valuation-for-quality. Additionally, we find that when the quality is of medium level, the firm and the platform may achieve a consensus on contract preferences on the wholesale price contract or the consignment contract, critically dependent on the informative degree.

The rapid development of online ride-hailing sharing economic platform provided an efficient way to mitigate the carbon emission of modern traffic in China. However, its development was blocked by the social management system whose update is relatively slow. How to resolve the conflict between the new economic paradigm development under the technology empowerment and the old public administration system and effectively solve the new economic and social problems it brought by are the major challenges for the healthy and sustainable development of this type of sharing economy. To shed light on the solutions to such conflict, the present paper conducts a case study on China’s largest online ride-hailing platform ‘Didi Chuxing’. The results indicate that the separation of ownership and use rights following the sharing economy brings a new approach to the efficient use of resources. The development of Didi displays a bottom-up policy innovation and institutional change. The path choice of enterprise development will affect its acquisition of legitimacy to a great extent. In this mobile Internet era, the public plays a critical role in shaping the new policy.

The objective of this research is to put forward a toughening method by using the polyamide non-woven fabric (PNF) and investigate the Mode-I fracture toughness and delamination characteristic of the toughened CFRP laminates by performing the double cantilever beam test. The effect of PNF interlayer, which is formulated by a bilinear cohesive zone model, on the Mode-I fracture of U3160-PNF/3266 laminated composites is numerically analyzed. And the intralaminar damages are considered by using strength criteria and stiffness degradation law. The influences of PNF/3266 interlayer strength, U3160/3266 laminate thickness and initial crack length on the mechanical response of laminates are studied systematically. The work by combining the experiment and simulation is helpful for the optimal design of laminated composites used in aerospace and civil engineering.

A constitutive model is constructed to consider the resin matrix post-yield softening and progressive hardening behaviors. A user-defined material mechanical behavior (UMAT) subroutine is created, then the non-linear three-dimensional finite element analysis on the tensile processes of multi-fiber composites is conducted. The approximate 45° shear bands emanating from the matrix crack tip are found, being coincided with the experimental observations. The shear stress on the adjacent intact fiber/matrix interface is strongly influenced by the shear band and thus the stress concentration factor (SCF) changes obviously in the adjacent fibers. The distinct stress redistribution in the adjacent intact fibers implies the significant effect of the shear bands on the progressive fiber fracture initiation. As the inter-fiber spacing increases, the peak value of the SCF in the adjacent intact fiber decreases, whereas the overload zone becomes wider. The research has provided a helpful tool to evaluate the failure of fiber composites and optimize the composite performance through the proper selection of resin matrix properties and fiber volume fraction.