Characteristics and control mechanisms of coalbed permeability change in various gas production stages

According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.

Chromatograph Skeleton Components of Feng-flavor Baijiu during Different Production Stages

Production of Feng-flavor baijiu includes six stages(first fermented stage,second fermented stage,third fermented stage,normal fermented stage and quitting fermented stage,ending of fermented stage).Each stage of the base liquor has its own style.The main chromatogram structure components were analyzed by gas chromatography(GC),to explore the characteristics of base baijiu during different production stages,which can provide a reference for classification storage and body design of baijiu.

Has Global Division of Labor Increased Markup of Chinese Enterprises?

The paper calculates the number of production stages for measurement of production segmentation,and discusses and depicts the microscopic impacts and effects of production segmentation of labor division of the global value chain on enterprise markup.The DLW method is used to calculate the markup of Chinese enterprises,the fi xed-effect model is used to analyze the impact of labor division of the global value chain on enterprise markup,and an instrumental variable method is constructed to relieve endogeneity.The research findings show that enterprises have significantly increased their markup by choosing global production segmentation,international production segmentation and domestic production segmentation.Global production segmentation can significantly increase the markup of low-productivity enterprises,hi-tech enterprises and private enterprises.Particularly,low-productivity enterprises choose international production segmentation and hi-tech enterprises choose domestic production segmentation.Production segmentation can offset to a certain extent low markup of export enterprises and domestic-oriented enterprises caused by the“competition effect”.In addition,enterprises’“technological progress effect”and“trade cost effect”are two possible channels by which production segmentation facilitates the increase of markup.The paper enriches and expands the literature about the impacts of labor division of the global value chain on enterprise markup,the robustness is analyzed from the perspectives of enterprise heterogeneity,industrial&technical heterogeneity and structure,and the impact mechanism is validated through the intermediate effect model.Our important findings are of important implications for solving the“low markup trap”of Chinese enterprises and enhancing labor division of the global value chain of enterprises.

Optimal advertising duration for profit maximization

The current research elucidates the advertising scheme of automotive innovation by incorporating the various stages of the product life cycle.The study proposes an empirical model for the automotive industry to evaluate a time-point known as a switch-point or a take-off point at which firms should modify the advertising and sales promotion strategies to boost sales volume.The problem applies a time-series innovation diffusion model wherein adoption rate changes when a product enters a growth stage and then again when the company stops the advertising campaign in the maturity stage.The present paper develops a profit maximization problem,which optimizes the overall advertising duration and advertising take-off point.A numerical illustration is provided using the actual sales data of automobile industries,and sensitivity analysis is further performed to validate the effect of critical parameters on the optimization problem.