No abstract

China is currently the world’s largest energy consumer and carbon emitter. In order to reduce the harm of carbon dioxide to the global ecological environment, the use of natural gas instead of coal is a realistic choice for China to achieve the “dual carbon” goal. Opportunities also bring new challenges, and the price of natural gas is an important method of promoting the upstream and downstream industrial chains of natural gas, so it is of great practical significance to study the price of natural gas. This paper builds a three-level supply chain model consisting of suppliers in the natural gas market, city gas companies and consumers in the market and uses the Stackelberg game to study the decision-making models of different subjects under their own dominance and centralized decision-making; it also considers the pricing mechanism and profit situation of stakeholders in the natural gas market under the low-carbon preference of consumers and the level of corporate carbon emission reduction. The research results show that when considering consumers’ low-carbon preferences, the sales prices of various stakeholders in the market have increased, which is beneficial for all entities in the natural gas industry chain. At the same time, with the low-carbon transformation of energy companies, the production method drives the price of raw materials to rise in the process of low-carbon innovation, which, in turn, makes the price of various stakeholders in the natural gas market and the level of carbon emission reduction per unit show a positive relationship; in order to maximize the overall profit of the supply chain, the natural gas market should adopt a centralized decision-making method to further promote the reform of China’s natural gas marketization.

A hydrate bed critical velocity model is developed, including a hydrate bed limit deposition velocity model and a hydrate bed suspension velocity model. The innovation of this paper is to consider the hydrate bed pressure and liquid bridge force on hydrate particles when building the limit deposition velocity model and to modify Dai’s model by using hydrate experimental and simulation data when building the suspension velocity model. The hydrate bed critical velocity model is negatively correlated with the particle size and positively correlated with the pipe diameter, particle density, and particle volume fraction. The accuracy of the model is demonstrated by validation. The hydrate bed critical velocity model can be used to calculate the hydrate fixed-bed and moving-bed height under different conditions, based on which the flow pattern map of hydrate particles and the hydrate blockage risk classification method are established, which is a certain guidance to ensure the safety of hydrate flow in the pipeline.

With the rapid development of intelligent technology, the construction of smart cities with the goal of creating a harmonious human life has become a new hot spot in the world. A new round of information technology revolution, represented by the Internet, big data, cloud computing, artificial intelligence (AI), and fifth-generation mobile communications (5G), is driving profound changes in the automotive industry. Smart vehicles (also known as intelligent connected vehicles) that integrate many high-tech technologies to provide safer, more convenient, and low-carbon comprehensive travel solutions have become an inevitable form of future vehicles. This paper constructs a three-level supply chain consisting of high-performance chip suppliers, smart car manufacturers, and retailers. On the basis of considering the level of product innovation and sales effort, Stackelberg game method is used to study the influence of each player in the supply chain on each parameter and the profit of each player under three scenarios: centralized decision making, nonsharing of innovation cost, and sharing of innovation cost. The results show that: when the level of sales effort has nothing to do with the level of innovation, the level of product innovation and the total profit of the supply chain increase with the improvement of the retailer’s sales ability; when the level of sales effort is related to the level of innovation, the level of product innovation under the cost-sharing decision model is greater than the case of no cost sharing, but the total profit of the supply chain is less than the case of no cost sharing.

Hydrate control has always been essential to oil and gas pipeline flow assurance work. To study the decomposition process of the hydrate deposition layer in the gas–water system, the decomposition experiments of the hydrate layer on the gas-phase pipe wall under different heating temperatures, different depressurization rates, and the combined action of heating and depressurization were carried out by using a high-pressure transparent rock-flow cell with a voltage detection system. The dynamic decomposition process was observed, and it was found that the decomposition rate was faster when decomposed by the depressurization method compared to the heating method. The decomposition process of the hydrate layer was quantitatively analyzed based on the voltage signal, and an electrical signal-based method for monitoring the decomposition of the hydrate layer on the pipe wall was proposed. The decomposition mechanism of the hydrate layer in different ways is summarized. During decomposition by heating, the hydrate layer decomposes in the mode of shrinkage ablation. During depressurization decomposition, it decomposes in the mode of differential ablation with the shedding phenomenon. The impact force generated by the gas release is the main reason for hydrate layer shedding. Shedding of the mixture of ice and hydrate occurs at depressurization rates ranging from 0.026 to 0.056 MPa/s, with the risk of ice blockage. This work provides further insight into hydrate decomposition in gas–water flow systems.