Effect of weakening characteristics of mechanical properties of granite under the action of liquid nitrogen

Liquid nitrogen fracturing and hot dry rock geothermal development are both emerging technologies in the field of energy. However, during the extraction of geothermal energy, it can cause the evolution of geological fractures, leading to the diffusion of groundwater and pollutants, thereby causing environmental pollution issues. Currently, geothermal energy has become a focal point in the global development of renewable energy. However, traditional hydraulic fracturing methods used in harnessing geothermal resources suffer from limitations such as limited fracture creation, uncertain initiation points, and environmental pollution. In contrast, liquid nitrogen has emerged as a promising reservoir stimulation technique, exhibiting significant effects on rock fracturing. In this study, we conducted three-point bending tests on granite samples subjected to liquid nitrogen treatment at temperatures of 300°C, with varying numbers of cooling cycles. Changes in fundamental mechanical parameters were analyzed. Additionally, through acoustic emission monitoring, we studied the variations in characteristic parameters of acoustic emissions under different cooling cycle conditions. Furthermore, based on the theory of energy evolution, we analyzed the energy evolution process during sample failure under different cooling cycle conditions. Using a compact scanning electron microscope, we observed changes in the microstructure of granite and analyzed the influence of cooling treatment on its surface characteristics and failure modes, thereby revealing the thermal damage process of granite. Moreover, by employing a non-metallic ultrasonic testing analyzer, we scanned the fracture surface morphology of granite and investigated the variations in fracture surface morphology features and surface roughness parameters caused by cooling treatment. The results indicate that liquid nitrogen cooling treatment can more effectively reduce the mechanical properties of rocks, and this effect is further enhanced at high temperatures. Under the condition of 300°C, after undergoing different cycles of liquid nitrogen cooling, granite will exhibit a more diverse macroscopic and microscopic structural failure characteristics, consistent with the expected formation of fluid flow channels in high-temperature rock formations

Research on High-Speed Railway Pricing and Financial Sustainability

With the steady increase of corporate system reform in the railway transportation industry, high-speed railways have accelerated their steps toward marketization, and the market competition they face has become increasingly fierce. In this context, enterprises need to make quick adjustments to new changes in order to seize the market share, obtain stable ticket income, and eventually, achieve financial sustainability while ensuring the healthy development of high-speed railways. Thus, it is particularly important to determine a reasonable ticket price. While considering supply and demand, market competition, and passenger utility, this study constructs a model of the passenger flow sharing rate and applies it to modeling the optimal ticket price for high-speed railways, taking the Beijing–Shanghai High-speed Railway as an example for calculating this model. Using the results calculated, this study analyzes the influence of the optimal ticket price on the financial sustainability of the enterprise through use of the evaluation system of financial sustainability established above. The results show that the existing price for a train ticket from of Beijing to Shanghai is not the optimal one, and there is still room for a price increase; the ticket price has an impact on financial sustainability by affecting corporate operating income and cash flow. The study provides a method for formulating the optimal ticket price for high-speed railway travel and enriches the research on the financial sustainability of high-speed railways

Can Rural Road Construction Promote the Sustainable Development of Regional Agriculture in China?

The sustainable development of agriculture is significant in protecting natural resources, protecting the ecological environment, ensuring food security, and eliminating poverty. Rural road construction promotes the flow of labor and capital between urban and rural areas, and plays a vital role in agricultural production and rural revitalization. This study aims to analyze the effect of rural road construction on the sustainable development of regional agriculture in China. We select five-dimensional indexes of population, society, economy, resources, and environment and use the entropy method to calculate the agricultural sustainable development index of each province in China. Then, we construct the spatial econometric model to explore the influence based on the panel data of 31 provinces in China from 2002 to 2018. The benchmark results show that rural road construction significantly promotes the sustainable development of agriculture; however, it has a negative impact on environmental sustainability, and the influence is lagging. The results are also heterogeneous among regions. Rural road construction has significantly promoted the sustainable development of agriculture in eastern and central areas, but has no significant impact on western regions. The reason is that the siphoning effect caused by the construction of rural roads has led to a loss of talents and capital in the western region, which harms the sustainable development of the population and resource system. This effect offsets the positive effect of the other three systems. This research has substantial policy implications for promoting rural revitalization and agricultural development

Cu3Sn joint based on transient liquid phase bonding of Cu@Cu6Sn5 core–shell particles

Abstract With the development of high-integration and high-power electronics, the lack of matching chip connecting materials that can withstand high temperatures has been a challenge. In this manuscript, a Cu@Cu6Sn5 core–shell bimetallic particles (approx. 1 μm in diameter) are successfully prepared and introduced as a new solder material for the packaging of power devices to obtain a Cu3Sn all-IMC solder joint. The joint consisted mainly of equiaxed Cu3Sn grains, and a small portion of columnar Cu3Sn grains. In columnar-type growth, Sn is the dominant diffusing species, which comes from the depletion of Sn in Cu6Sn5. The depleted Cu6Sn5 is transformed into columnar Cu3Sn. In equiaxed-type growth, Cu is the dominant diffusing species. Cu reacts with Cu6Sn5 to grow a Cu3Sn layer. This conclusion was confirmed by the orientation relationship. The equiaxed Cu3Sn grain nucleates at the Cu/Cu3Sn interface have an orientation relationship with the Cu substrate. Columnar Cu3Sn grains at the Cu6Sn5/Cu3Sn interface have an orientation relationship with Cu6Sn5

Sustainable Mechanism of the Entrusted Transportation Management Mode on High-Speed Rail and the Impact of COVID-19: A Case Study of the Beijing–Shanghai High-Speed Rail

The transport management mode fundamentally determines the sustainable development of high-speed rail passenger transport (HSRPT), which was shocked by the COVID-19 pandemic in 2020. In order to study the sustainable development mechanism of HSRPT and the impact of COVID-19, primarily based on the data from the Beijing–Shanghai high-speed rail (HSR) taken from 2018, we adopt system dynamics (SD) to provide a scenario simulation method to examination sustainable operation status of HSRPT under the entrusted transportation management mode (ETMM) by VENSIM, and take into account the following two evaluation indicators: economic and operational. The results show the following: (1) Transportation demand and commissioned transportation management fees play a vital role in the sustainable operation of the Beijing–Shanghai HSR, causing significant changes in transportation revenue and transportation costs. (2) COVID-19 had a great impact on the sustainable operation of the Beijing–Shanghai HSR. In 2020, the turnover and transportation profit of the Beijing–Shanghai HSR fell by 74.31% and 49.19%, respectively. In 2022, the transportation profit can be restored to the level of 2019. The study results reveal that Beijing–Shanghai HSR under the ETMM has a good sustainable development capability

Design and evaluation of silage equipment control panel based on the theory of emotional design and Kansei Engineering

In order to make the silage equipment control panel meet user needs better and translate user requirements into product design elements, this paper puts forward the design model of silage equipment control panel based on the theory of emotional design and Kansei Engineering. Firstly, qualitative and quantitative analyses of silage equipment control panel were conducted according to the results of the user survey. Then, the prior design elements and the “Feature-Vocabulary” correspondence were obtained, which were applied to the design of silage equipment control panel. Finally, the design plan was evaluated using semantic differential method. As a result, it is initially verified that the design model has certain feasibility for translating user requirements into product design elements

Tool Wear Monitoring in Milling Based on Fine-Grained Image Classification of Machined Surface Images

Cutting tool wear state assessment during the manufacturing process is extremely significant. The primary purpose of this study is to monitor tool wear to ensure timely tool change and avoid excessive tool wear or sudden tool breakage, which causes workpiece waste and could even damage the machine. Therefore, an intelligent system, that is efficient and precise, needs to be designed for addressing these problems. In our study, an end-to-end improved fine-grained image classification method is employed for workpiece surface-based tool wear monitoring, which is named efficient channel attention destruction and construction learning (ECADCL). The proposed method uses a feature extraction module to extract features from the input image and its corrupted images, and adversarial learning is used to avoid learning noise from corrupted images while extracting semantic features by reconstructing the corrupted images. Finally, a decision module predicts the label based on the learned features. Moreover, the feature extraction module combines a local cross-channel interaction attention mechanism without dimensionality reduction to characterize representative information. A milling dataset is conducted based on the machined surface images for monitoring tool wear conditions. The experimental results indicated that the proposed system can effectively assess the wear state of the tool