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Realizing the synergy of regional economic growth and ecological development can not only effectively promote the construe -tion of ecological civilization, but also help accelerate the green transformation of the development mode. For this, from the perspective of strong sustainability and the common frontier theory, using the panel data of 285 prefecture-level cities in China from 2011 to 2020 and considering the characteristics of regional technological heterogeneity, this study used the three-stage SBM model based on the common frontier to measure urban ecological total factor productivity. The study also used the spatial Durbin panel model to analyze the spatial spillover effects and influencing factors of urban ecological total factor productivity. The findings showed that: (J) After excluding the influence of external environmental factors and random factors, the ecological total factor productivity of each region decreased significantly compared with that before the improvement. From the perspective of average efficiency by region, there was a characteristic of east>northeast>west>center. © Under different spatial weight matrices, urban ecological total factor productivity had obvious spatial spillover effects, and there were differences in characteristics. © From the perspective of geographical location, economic development level, and resource endowment differences, the spatial spillover effects of ecological total factor productivity in China's eastern regions and non-resource depletion cities were more obvious, while those in the central and western regions, northeastern regions, and resource depletion cities were average. © The improvement of urban ecological total factor productivity could not be separated from the cooperation and exchange between neighboring regions, thus forming a development pattern of partnership with mutual benefits. Therefore, in the new era of China's economic transformation and development, it is necessary to pay attention to improving the efficiency of factor and resource utilization and fully consider the technological gaps between different regions. At the same time, it is also necessary to deepen and coordinate the pattern of regionally coordinated development, improve the innovation systems and mechanisms in policy formulation, and promote the sustainable growth of regional ecological total factor productivity so as to form a mutually beneficial and win-win development pattern among regions. [ABSTRACT FROM AUTHOR]

In order to solve the problem of poor mechanical properties of laser cladding In718 alloy, different scanning speeds were selected to carry out laser remelting treatment of the cladding layer. Optical microscope, scanning electron microscope and energy dispersive spectrometer were used to observe the microstructure and characteristics and to detect the composition of different phases. The influence of microsegregation on the microstructure was then analyzed. The microhardness and tensile strength of the coating were tested by mechanical testing equipment. The results show that the Laves phase is mainly caused by the segregation of Nb and Mo elements. Compared with the non-remelted coating, the pores of the remelted coating are significantly reduced, and different remelting scanning speeds have different effects on the structure and properties. The Laves phase volume fraction of four coatings respectively decreased from 34. 1% to 24. 6%, 16. 7%, and 19. 6%, the average hardness respectively increased from 250.3 HV to 261.5 HV, 276.9 HV, and 268.0 HV. The tensile strength respectively increased from 678 MPa to 728 MPa, 879 MPa, and 808 MPa. However, the effect of remelted coating on elongation is not obvious. The optimum remelting scanning speed is 15 mm/s, which has the lowest Laves phase content and the highest average microhardness and tensile strength. Laser remelting can effectively improve the morphology of the cladding layer, reduce the porosity, reduce or inhibit the precipitation of Laves phase. Reducing the Laves phase to improve the mechanical properties of In718 alloy. This research establishes a theoretical foundation for the subsequent remanufacturing of centrifugal cast ductile iron pipes molds. [ABSTRACT FROM AUTHOR]

In the real-world production process, the firms need to determine the optimal production planning under minimum production quantity constraint in order to achieve economies of scale. However, the inventory cost will hugely increase when there is a very large amount of production in a period and also a large amount of total demands for the next few periods. This paper considers a single-item dynamic lot sizing problem with production-or-outsourcing decisions. In each period, the production level cannot be lower than a given quantity in order to make full use of resources, but the outsourcing is unrestricted. The demands in a period can be backlogged. The production and outsourcing costs are fixed-plus-linear, and the inventory and backlogging costs are linear. We establish a mathematical programming model according to the real problem in the firm. We explore some structural properties of the optimal solution and use them to develop a dynamic programming algorithm to solve the proposed problem. We further present a special case with stationary production and outsourcing costs which can be solved with reduced computational complexities. In the end, we use three numerical instances to show how to obtain the optimal solutions by using the dynamic programming algorithm. Furthermore, we show that the policy of backlogging or outsourcing can reduce the total cost. [ABSTRACT FROM AUTHOR]