Search

Inclusions are one of the important factors affecting the cleanliness of molten steel. The current optimization of inclusion removal methods mainly focuses on promoting inclusions to float to the slag–steel interface so that the inclusions can be absorbed and removed by the refining slag. However, the research on the floating removal of inclusions cannot be carried out directly in the ladle, so methods such as mathematical models and physical models were developed. This article uses silicone oil to simulate the slag layer; polypropylene particles; and aluminum oxide particles to simulate inclusions to establish a water model experiment. By changing the viscosity of silicone oil and the diameter of particles, the factors affecting the movement of inclusions at the slag–steel interface were explored. Based on the water model, a mathematical model of the floating behavior of inclusions at the slag–steel interface was constructed, and parameters such as particle diameter and interfacial tension in the water model experiment were studied by the mathematical model for calculation. Both the mathematical model and the water model experimental results show that after the viscosity of silicone oil increases from 0.048 Pa·s to 0.096 Pa·s, the dimensionless displacement and terminal velocity of the particles decreases. When the diameter of the same particle increases, the dimensionless displacement and terminal velocity increases. The dimensionless displacement of polypropylene particles of the same diameter is larger than that of aluminum oxide particles, and the terminal velocity is smaller than that of aluminum oxide particles. This is attributed to the better overall three-phase wettability of polypropylene particle. When the liquid level increases, the dimensionless displacement and terminal velocity of particles under the same conditions show only slight differences (less than 10%). [ABSTRACT FROM AUTHOR]

Coordination between ecological security and economic development is crucial to sustainable development, with a development strategy that should be adjusted according to the type of region. Yunnan Province, China, is a treasure trove of biodiversity but is economically lagging. Clarifying the relationship between ecological security and economic development can provide a reference for the sustainable development of similar biodiversity hotspots in the world. The landscape index method and index evaluation method were used to calculate the ecological safety index (ESI) and the economic development index (EDI), respectively, and the median value of the indices was used for the comprehensive zoning. The coupled coordination degree model (CCDM) was used to assess the coordination status of ecological safety and economic development in each zone. The results show that (1) Yunnan's ecological security pattern is high in the west and low in the east, mainly influenced by topography, climate, and human activities; its economic development is resource-dependent and shows a multi-point dispersed pattern due to poor transportation; (2) Yunnan was partitioned into the Coordinated Development Zone (CDZ), the Ecological Risk Zone (ERZ), the Economic Poverty Zone (EPZ), and the Dual Pressure Zone (DPZ). Among them, CDZs (15%) are mostly areas with outstanding advantageous resources, mature characteristic industries, and relatively spatially dispersed. There are two types of ERZs (35%): one is an area where the intensity of human activities exceeds the ecological carrying capacity, mainly located in the eastern plateau; the other is an area with fragile ecological background conditions, located in high mountains and river valleys. EPZs (35%) are mainly lagging in socioeconomics of DPZ (15%) and the fragile ecological environment constrains each to form a negative cycle. (3) Of the regional coordination levels in Yunnan Province, 76% are moderately coordinated, and there is still space for development from the high-quality coordination level. The order of the average coordination degree of each partition is CDZ > ERZ > EPZ > DPZ. The poor basis for coordination and the single approach to coordination have led to ecological safety and economic development often being more difficult to achieve in areas with large mountainous areas similar to Yunnan. (4) Due to the necessity for biodiversity protection, Yunnan Province should choose the sustainable path of ecological priority and green development. Specifically, CDZ should play to industrial advantages and brand effects, and promote industrial integration and innovative industrial development paths. The keys to ERZ are industrial restructuring, industrial ecologization, and ecological environment restoration and protection. EPZ should improve transportation and other infrastructure and revitalize economic development under the premise of ecological priority. Finally, DPZ should emphasize human and load reduction, and moderate development. [ABSTRACT FROM AUTHOR]

Rapid urban expansion and economic development lead to the deterioration of ecosystems, which not only aggravates regional ecological risks but also leads to the degradation of ecosystem functions. It is of great significance to rationally divide regions and provide targeted management strategies for realizing the sustainability of regional economic development and ecological maintenance. Taking southwest China (Sichuan, Yunnan, Guizhou and Chongqing) as an example, land use data from 2000, 2010 and 2020 were used to evaluate the value of landscape ecological risk (LER) and ecosystem services, and comprehensive zoning was divided according to their spatial correlation. The socio-economic development characteristics of each zone were analyzed, and differentiated and targeted sustainable development paths were proposed. The results showed that the overall LER level of southwest China increased, and the gap of internal LER narrowed gradually. The ecosystem service value (ESV) per unit area showed an increasing trend, but the core metropolitan areas and northwest Sichuan had little change. According to the differences in population, industrial structure and land use, the low-ESV zone was densely populated, while the high-ESV zone was sparsely populated, and the population from the high-LER zone gradually migrated to the low-LER zone. The economic development of the low-ESV zone was better than that of the high-ESV zone, and secondary industry was an important driving force of regional economic development. Large-scale forestland can alleviate the LER, but the increase in cultivated land and grassland further aggravated the LER. According to the social and economic characteristics of each zone, this study put forward a differentiated development strategy for southwest China and also provided reference for the coordinated development of ecological protection and social economy in other key ecological regions. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO), a chemically oxidized sheet of graphite, has been used as a conductive carbon carrier of microbes to boost various bioelectrochemical reactions. However, the types of microbes that can reduce GO have rarely been investigated. In this study, a strain of GO-reducing bacteria, named NIT-SL11, which was obtained from a hydrogel of microbially reduced GO and anaerobic sludge that converts sewage to electricity, was phylogenically identified as a novel strain of Geotalea uraniireducens. Considering the current lack of information on the electrogenic ability of the bacterium and its physicochemical and chemotaxonomic characteristics, the polyphasic characterization of the Geotalea uraniireducens strain NIT-SL11 was performed. NIT-SL11 utilized various organic acids, such as lactate, benzoate, and formate, as electron donors and exhibited respiration using GO, electrodes, fumarate, and malate. The strain contained C16:1ω7c and C16:0 as the major fatty acids and MK-8 and 9 as the major respiratory quinones. The complete genome of NIT-SL11 was 4.7 Mbp in size with a G+C content of 60.9%, and it encoded 80 putative c-type cytochromes and 23 type IV pili-related proteins. The possible extracellular electron transfer (EET) pathways of the strain were the porin–cytochrome (Pcc) EET pathway and type IV pili-based pathway. [ABSTRACT FROM AUTHOR]

This paper presents a novel superposition method for effectively predicting the microscopic stresses of heterogeneous periodic beam-like structures. The efficiency is attributed to using the microscopic stresses of the unit cell problem under six generalized strain states to construct the structural microscopic stresses. The six generalized strain states include one unit tension strain, two unit bending strains, one unit torsion strain, and two linear curvature strains of a Timoshenko beam. The six microscopic stress solutions of the unit cell problem under these six strain states have previously been used for the homogenization of composite beams to equivalent Timoshenko beams (Acta. Mech. Sin. 2022, 38, 421520), and they are employed in this work. In the first step of achieving structural stresses, two stress solutions concerning linear curvatures are transformed into two stress solutions concerning unit shear strains by linearly combining the stresses under two unit bending strains. Then, the six stress solutions corresponding to six generalized unit beam strains are combined together to predict the structural microscopic stresses, in which the six stress solutions serve as basic stresses. The last step is to determine the coefficients of these six basic stress solutions by the principle of the internal work equivalence. It is found that the six coefficients, in terms of the product of the inverse of the effective stiffness matrix and the macroscopic internal force column vector, are the actual generalized strains of the equivalent beam under real loads. The obtained coefficients are physically reasonable because the basic stress solutions are produced by the generalized unit strains. Several numerical examples show that the present method, combining the solutions of the microscopic unit cell problem with the solutions of the macroscopic equivalent beam problem, can accurately and effectively predict the microscopic stresses of whole composite beams. The present method is applicable to composite beams with arbitrary periodic microstructures and load conditions. [ABSTRACT FROM AUTHOR]

The greenhouse effect and plastic pollution caused by the accumulation of plastics have led to a global concern for environmental protection, as well as the development and application of biodegradable materials. Polypropylene carbonate (PPC) is a biodegradable polymer with the function of "carbon sequestration", which has the potential to mitigate the greenhouse effect and the plastic crisis. It has the advantages of good ductility, oxygen barrier and biocompatibility. However, the mechanical and thermal properties of PPC are poor, especially the low thermal degradation temperature, which limits its industrial use. In order to overcome this problem, PPC can be modified using environmentally friendly materials, which can also reduce the cost of PPC-based products to a certain extent and enhance their competitiveness in terms of improving their mechanical and thermal properties. In this paper, we present different perspectives on the synthesis, properties, degradation, modification and post-modification applications of PPC. The modification part mainly introduces the influence of inorganic materials, natural polymer materials and degradable polymers on the performance of PPC. It is hoped that this work will serve as a reference for the early promotion of PPC. [ABSTRACT FROM AUTHOR]

The lithium-ion battery (LIB) has the advantages of high energy density, low self-discharge rate, long cycle life, fast charging rate and low maintenance costs. It is one of the most widely used chemical energy storage devices at present. However, the safety of LIB is the main factor that restricts its commercial scalable application, specifically in hazardous environments such as underground coal mines. When a LIB is operating under mechanical and electrical abuse such as extrusion, impact, overcharge and overheating, it will trigger thermal runaway and subsequently cause fire or even an explosion. According to the relevant requirements in IEC60079, the explosion-proof protection of LIB can be adapted to the working environment of high dust and explosive gas environments such as in the mining face of coal production. This paper presents an overview of the LIB-relevant technology, thermal runaway, safety and applications in the general mining industry with implications to establish a theoretical and technical basis for the application of high-capacity LIBs in the industry. These then promote intelligent, safe and efficient production not only for the coal mine industry but also for non-coal applications. [ABSTRACT FROM AUTHOR]

This paper studies hydraulic cylinder position adjustment controlled by an on–off valve. The aim of this paper is to develop a method of position control for a hydraulic cylinder based on input and output pressure under the mutual coupling feedback of the load and flow, especially in multi-actuator coupling control scenarios. This method can solve the problem of position evaluation and hydraulic cylinder tracking in relation to position detection without a displacement sensor and provide the possibility of automatic adjustment of hydraulic support in the process of intelligent mining. First of all, according to the flow continuity equation and Navier–Stokes equation, a flow model with inlet and outlet pressure is derived. Secondly, the effectiveness of the flow resistance characteristic curve of differential valve is verified by experimental and theoretical analysis. Finally, through experimental verification, when the system pressure is larger than 10 MPa, the error between the actual experimental data and the data calculated by the fitting algorithm is within 5%, which is consistent with the derived formula and proves the validity of the simulation model. [ABSTRACT FROM AUTHOR]

This paper studies the precise position control of the hydraulic cylinder in the hydraulic support. The aim of this paper is to develop a method of hydraulic cylinder position control based on pressure and flow coupling, which takes the coupling feedback of load and flow into account, especially in the scene of cooperative control under the condition of multiple actuators and variable load. This method solves the problems of slow movement and sliding effect of hydraulic support in the traditional time-dependent hydraulic position control, as well as better realizes the intelligent and unmanned development of the fully mechanized mining face. First, based on the flow continuity equation and Newton Euler dynamic equation, the flow and stroke control model with the input and output pressure of hydraulic cylinder is established. Then, the effectiveness and correctness of the control model are verified by the comparison between the hydraulic system simulation software, AMESim, and the experiment. Finally, a test system is built. When the system pressure is large than 10 MPa, the error between the data determined by the fitting algorithm and the actual detection data is within 5%, which verifies the effectiveness of the theory and simulation model. [ABSTRACT FROM AUTHOR]

In this study, a novel electrogenic bacterium denoted as strain NIT-T3 of the genus Desulfuromonas was isolated from a graphene-oxide-reducing enrichment culture that was originally obtained from a mixture of seawater and coastal sand. Strain NIT-T3 utilized hydrogen and various organic acids as electron donors and exhibited respiration using electrodes, ferric iron, nitrate, and elemental sulfur. The strain contained C16:1ω7c, C16:0, and C15:0 as major fatty acids and MK-8, 9, and 7 as the major respiratory quinones. Strain NIT-T3 contained four 16S rRNA genes and showed 95.7% similarity to Desulfuromonasmichiganensis BB1T, the closest relative. The genome was 4.7 Mbp in size and encoded 76 putative c-type cytochromes, which included 6 unique c-type cytochromes (<40% identity) compared to those in the database. Based on the physiological and genetic uniqueness, and wide metabolic capability, strain NIT-T3 is proposed as a type strain of 'Desulfuromonas versatilis' sp. nov. [ABSTRACT FROM AUTHOR]