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As construction continues, a large number of concrete engineering facilities will be put into use in permafrost areas, which poses a challenge to the long-term service of concrete materials. To investigate the evolution of strength and pore structure of concrete under the cold permafrost environment, concrete compressive strength tests and mercury intrusion tests were performed at four molding temperatures (5°C, 10°C, 15°C, and 20°C) under continuous −5°C curing and standard curing conditions. Under negative-temperature curing, the strength of concrete at an early age reached about 80% that of standard curing; however, its strength at a later age was comparable to that at 28 days under standard curing. Under negative-temperature curing, the most probable pore size and porosity at 28 days of age were larger than those under standard curing. Increasing the molding temperature was beneficial for the promotion of the internal hydration reaction of concrete, refining its microscopic pore structure, and promoting its strength development. The strength of concrete with different porosities and average pore diameters could be predicted better using the Atzeni model or the bivariate Hasselmann model. Based on maturity theory, an equivalent age model of concrete under a permafrost temperature environment was established. The prediction deviation of the model was controlled within ±5% , so the model can be used to predict the time-dependent strength of concrete in permafrost zones. [ABSTRACT FROM AUTHOR]

In the digital economy era, traditional manufacturing enterprises face a significant challenge due to fierce competition regarding products, channels, digital technology, management, and core competencies. As a result, many enterprises strive to leverage digital technology to gain new processes, products, services, and business models, thereby enhancing their competitive edge. This paper mainly focuses on how digital innovation based on different value-creation methods can help enterprises build their core competence. Using a sample of 254 questionnaires from manufacturing enterprises in China, this study investigates whether and how efficiency-based, convergence-based, and generativity-based digital innovation supports the development of core competence using ordinary least squares (OLS) regression. Further, this paper examines the moderating effect of absorptive capacity. The empirical results indicate that digital innovation encourages the establishment of core competence, and absorptive capacity strengthens the role of efficiency-based digital innovation but inhibits convergence-based and generativity-based digital innovation. This study contributes to a clearer understanding of the significance of digital innovation for Chinese manufacturing enterprises and provides useful insights for other countries to rethink their innovation models. [ABSTRACT FROM AUTHOR]

Applying a Markov switching model (MSM) to Las Vegas and Macao, this paper decomposes their business cycles of the casino hospitality industry into high and low growth states (HGS, LGS). Compared with Las Vegas, casino gaming in Macao is more volatile due to larger ups and downs in tourism flows, with HGS being far higher and LGS being much lower. Gaming hospitality in both travel destinations has a strong tendency to stay in HGS, but a low chance of recovering from LGS. While the two cities' hospitality cycles are desirably asymmetric, Las Vegas's cycle seems more favorable than Macao's. Furthermore, in this paper, MSM is incorporated into a structural regression to identify determinants of hospitality cycles and generate policy implications useful for decision-making. It is observed that local hospitality cycles are affected by external business cycles and other demand- or supply-side factors. It is necessary for Las Vegas to strengthen promotional marketing and for Macao to pursue industrial diversification. [ABSTRACT FROM AUTHOR]