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In this study, the fatigue life of load-carrying cruciform welded joints under various plate thicknesses and degrees of penetration was performed. The fatigue assessment results showed a significant “thickness effect.” The fatigue limit of the 25 mm-thick sample was 13.4% lower than that of the 16 mm-thick fatigue sample. Essentially, the fatigue life of the weld toe does not change with the degree of penetration. Plate thickness is the key factor affecting the fatigue life. The thickness effect is determined by both the stress gradient along the plate thickness and the degree of surface stress concentration. The correction result based on the effective notch stress approach is more accurate than the thickness correction formula in the ABS standard, which underestimates the thickness effect of load-carrying cruciform welded joints and may lead to danger. The penetration ratio a/t affects the fatigue failure position of load-carrying cruciform welded joints. The fatigue design of load-carrying cruciform welded joints can be performed by appropriately increasing the degree of penetration while achieving the damage at the weld toe.

Microspheres are widely used as profile control and water plugging products at present. However, the current research on microspheres is mainly focused on oil displacement experiments. In order to solve this problem, based on the Bohai sea in the BZ of inhomogeneous reservoir conditions, this article has done the matching study on particle size and hole roar and the seepage research in porous medium by means of particle size analysis, pressure tests, single-phase block experiments, and the double tube parallel oil displacement experiments, revealing the characteristics of oil & water selective plugging and the mechanism of oil displacement in porous media. The results show that the average particle size of the microspheres increases from 4.857μm to 24.53μm, and the maximum expansion factor reaches 5.03 times after 72h of swelling in BZ25 oilfield water at 75 C. In the two-pipe parallel oil flooding experiment with the permeability of 1000mD and 3000mD respectively, the comprehensive recovery rate after the first water flooding is 28.06%, and the two-pipe average recovery rate is increased by 1.58% after the injection of 2000ppm microsphere with 0.3PV, and there is no significant increase in oil displacement efficiency. The comprehensive recovery rate reached 38.6% and increased by 8.99% after 4PV of subsequent water flooding, indicating that microsphere flooding effectively improved the water sweep efficiency of subsequent injection.

With the continuous development of China’s industry, the disorderly discharge and accumulation of coal gangue in mining areas have become a key ecological problem, which not only occupies a large amount of land, but also causes various pollution phenomena. Therefore, the comprehensive utilization of coal gangue has become a research hotspot in the field of environmental governance. In this paper, by mixing coal gangue and fly ash with straw in different ratios to prepare compound soil substrate and growing lettuce, the effects of different ratios of the three wastes and coal gangue particle sizes on crop growth were analyzed by measuring cotyledon area, plant height and other indexes. The experimental results showed that the best proportion of soil matrix improvement was 42.9% coal gangue, 7.1% fly ash, 10% straw and 40% soil, where the coal gangue particle size proportion was 20% fine particles, 20% medium particles and 60% coarse particles. This experiment mixed coal gangue with typical solid wastes, which will, to a certain extent, solve the problem of solid waste dumping and resource scarcity in China and provide a scientific reference for the comprehensive utilization of the three wastes and the repair of soil in mining areas.

Under the trend of global carbon emission reduction and energy transformation, variable renewable energies (VREs mainly wind power and solar) will develop rapidly. Many countries have put forward ambitious VREs development plans, and a high penetration of VREs will have a significant impact on the grid. This paper focuses on the analysis of the influence of the VREs’ penetration on the capacity of transmission lines, establishes an analysis model based on mixed integer optimization and power transfer distribution factors (FTDFs), and uses this model to carry out a quantitative study on a typical system. Through the analysis of the research results, as the penetration rate of VREs increases, the transmission power of the transmission lines and the investment cost of the transmission lines will increase, and the line utilization rate will decrease. Utility companies should pay attention to the impact of future development of VREs on grid investment costs and recovery.

At present, the calculation method of steam extraction efficiency of power plant turbine have five methods: heat balance method, equivalent enthalpy drop method, cyclicfunctional method, composite structure method and matrix method. In this paper, a 600MW grade subcritical thermal power plan is take as an examplefor comparing the calculation by the simple heat balance method and the equivalent enthalpy drop method. The result shows that the computational results of simple heat balance method agree with equivalent enthalpy drop method. So simple heat balance method can be used to replace equivalent enthalpy drop method in order to reduce calculation amount in practicalapplication.

The German federal government has set very high targets for renewable energy. In recent years, Germany’s renewable energy has developed rapidly. Germany leads the world in energy transformation, with wind and solar generating capacity accounting for nearly half. Germany’s experience and practice in developing renewable energy are worthy of our country’s reference. In this paper, the development status of renewable energy and power grid in Germany is introduced. And this paper mainly analyzes Germany’s experience and practice in achieving a high proportion of new energy access in 2019.

It is difficult for computer to understand the texts in unstructured Chinese language, which becomes an obstacle for further application of artificial intelligence in the power dispatch center. Understanding of the orders from human dispatchers is the premise for the collaboration of machine and human being in power system operation. Towards understanding of dispatching texts, this paper proposes a textual semantic analysis framework with active learning of the semantic structure knowledge. Firstly, the words are vectorized by the Skip-gram models. And the hierarchical clustering algorithm is designed to detect the sentence patterns. Then the knowledge base is set up by converting the sentence structure to their regular expressions. In application, define a proprietary semantic framework to extract important device information and to parse the semantic slot using dependency syntax. Application shows that the Chinese texts describing the operation mode switching process can be understood accurately by the computer program.

In the background of energy transformation, the world has witnessed the rapid development of new energy generation, with the proportion of capacity and electricity continuously increasing. However, different countries and regions have great differences in the access level of new energy. When a high proportion of new energy is connected to the system, it is neither scientific nor reasonable to reflect the development and absorption level of new energy only by such indicators as the proportion of new energy installed and the proportion of electricity generated. This paper analyzes the development status of new energy at home and abroad, and constructs the evaluation index system of the access level of new energy in power grid. Based on the evaluation index system, the access levels of new energy in different countries and regions are compared and analysed. At last, several key issues that need to be solved to achieve the goal of high proportion of new energy access in China are put forward.

An enormous amount of acid gas, containing carbon dioxide (CO2) and hydrogen sulfide (H2S), is generated in the exploitation of oil and gas reservoirs in the Tarim Basin, China. An appropriate management plan is required to safely dispose of the acid gas, and common strategy considered for the safe disposal of acid gas is the injection of it into deep formations – this strategy mitigates greenhouse gas emissions and avoids costs associated with desulfurization. A feasibility assessment of acid gas injection requires a detailed investigation of the potential physical and geochemical impacts. Reactive transport simulations based on the mineralogical composition and the hydrochemical characteristics of a carbonate formation in the Tarim Basin were conducted to identify the physical and geochemical interactions of acid gas with the mineral matrix and formation water. Acid gas (59% CO2 and 41% H2S) was injected at a constant rate of 19 200 Nm3/d for 25 years, and the simulation was run by the TMVR_EOSG module of the TOUGHREACT code for a period of 10 000 years. The results indicate that the minimum liquid saturation is much larger than the residual water saturation, and the pressure buildup is below the allowable pressure increase. Additionally, the porosity change is found to be negligible due to the small changes in calcite and quartz in the volume fraction. From this perspective, acid gas injection in the carbonate formation of the Tarim Basin seems feasible. Furthermore, the fast breakthrough of CO2 can provide an advanced warning of a potential breakthrough of acid gas. Last, the injection rate can be increased to accelerate acid gas trapping, and the results could be used as guidance for future acid gas injection operations.

The inverse time domain boundary element method (ITBEM) that is derived from the direct time domain boundary element method by eliminating the retarded time is able to reconstruct the transient pressure and flux on the surface of an arbitrarily shaped source by measuring the pressure on a hologram surface. In the present work, the ITBEM is applied to reconstruct the transient pressure and acceleration over the surface of a tire which is supported away from the ground in a semi-anechoic chamber. The tire is impacted by a rigid sphere to generate a transient sound field, and the measurement is controlled by a trigger which is connected to an acceleration sensor stuck on the surface of the tire. The pressure and acceleration on the surface of the tire are reconstructed from the holographic pressure measured by array microphones. By visualizing the pressure and acceleration with respect to the elapsed time, the wave propagation phenomenon of the pressure and acceleration on the surface of the tire is shown clearly. The comparison of the reconstructed surface acceleration to the measured one demonstrates the effectiveness of ITBEM for transient sound field reconstruction.