Risk assessment of Ordovician limestone water inrush in No.9 coal seam of Yangdong coal mine and its prevention and control measures
With the increasing of mining depth, intensity, scale and speed, Ordovician limestone water has become the biggest threat to the safety production of the low group seam. Based on the existing geological data, the hydrogeological characteristics of Ordovician limestone water are analyzed; the risk of Ordovician limestone water inrush is evaluated by using the method of “five maps and double coefficients” and considering the importance of effective protective thickness of floor protective layer in the evaluation results. The results show that there are no non straight through relative safety area (Area I) and non straight type relative risk area (Area II), only non straight type water inrush risk area (Area III) and straight through water inrush risk area (Area IV). According to the evaluation results, the floor grouting reinforcement is directly adopted in Area IV, and the Ordovician limestone may need to be modified in the strong water rich area; in Area III, the grouting transformation of the floor is carried out after the area with water inrush is identified first, but the Ordovician limestone is not needed. Other prevention and control measures should be subsidiary.
Blasting flying stone is one of the six hazards in rock and soil blasting construction. In order to determine the risk level of blasting flying stone, 3 first-grade indexes such as blasting design and construction are selected, and 11 second-grade indexes such as warning range are not set, so as to establish the blasting flying stone safety evaluation model of AHP-GRA. The analytic hierarchy process (AHP) was used to calculate the weight of the evaluation index. The grey correlation method was used to determine the correlation degree between the blasting flying stone and the safety level of an airport. The risk level of an airport was calculated based on the weight of the evaluation index, and the engineering verification was carried out. The results show that there is no warning signal, no notice before detonation and the warning range is too small, which are the main factors of the flying stone accident. The model presented in this paper is used to evaluate the blasting flying stones in an airport, and the evaluation results are basically consistent with the reality. It can be seen that the evaluation model can scientifically and reasonably evaluate the risk level of blasting flying stones, which has important practical significance.
The term of postmodernism suggests that the period came after modernism (since the 70-90ss of the 20th century). Postmodern texts are marked by the mixture of times, cultures, languages, real facts and fiction, the present and the past. Postmodern literature is presented by such key figures in English literature as John Fowels , Julian Barns, Doris Lessing, A.S. Byatt, Peter Ackroyd, G. Swift, etc. Out of them we have chosen John Fowels’ novels because of his originality, versatility and skill were nowhere more evident than in his most celebrated novels, among them “The Collector,” “The Magus” and “«The French Lieutenant’s Woman».” In “«The French Lieutenant’s Woman»,” for example, he combined the melodrama of a 19th-century Victorian novel with the sensibility of a 20th-century postmodern narrator, offering his readers two alternative endings from which to choose and at one point boldly inserting himself into the book as a character who accompanies the hero on a train to London. His teasing, multilayered fiction explored the tensions between free will and the constraints of society, even as it played with traditional novelistic conventions and challenged readers to find their own interpretations.
Wheat is one of the major staple crops in Ethiopia in terms of both production and consumption. Even though it is such an important cereal crops in Ethiopia, it is giving low yield due to many production constraints such as lack of improved varieties, poor agronomic practice (inappropriate seeding rate and row spacing), diseases, weeds and low soil fertility in Ethiopia in general and in Guji zone in particular. Therefore, field experiment was conducted during the 2015-2017 main cropping season at Bore and Ana sora to assess the effect of seeding rate and row spacing on yield components and yield of bread wheat; and to determine appropriate seeding rates row spacing for bread wheat. The experiment was laid out RCBD in a factorial arrangement with three replications using a wheat variety known as ‘Huluka’ as a test crop. The treatments consisted of four levels of seeding rate (100, 125, 150 and 175 kg ha-1) and four levels of row spacing (15, 20, 25 and 30 cm) consisting a total of 16 treatments. Analysis of the results revealed that all parameters were significantly (P
This paper focuses on the application of nonlinear programming in solving the optimal selection strategy of generator. A nonlinear programming model for optimal scheme selection was established. Comparative analysis, numerical combination analysis and sensitivity analysis were used to solve the problem, and MATLAB, LINGO and other software were used to assist the calculation. According to the actual background provided in this paper, it can be concluded that the minimum cost of this factory in a week of power failure is 1868443.7 yuan without charging. If the remaining 20% of the battery is taken into account, the minimum charge is 2575502.0 yuan. After obtaining the results, the sensitivity analysis was carried out to improve the practicability of the results.
Seafood provides essential nutrients to the body. A study funded by CDC found that eating seafood for essential Omega-3 fatty acids can prevent 84,000 deaths each year [1-3]. According to a Harvard study, 3-ounce servings of fatty fish a week reduces the risk of dying from heart disease by nearly 40% . Eating 8 two servings of fish per week during pregnancy can improve baby’s IQ, cognitive development, and eye health [5,6]. Older adults with the highest fish consumption live and average of 2.2 years longer . But all these statements possess another side of the coin. Food-born poisoning, mercury-lead-arsenic-cadmium poisoning, exposure to polycyclic aromatic hydrocarbons (PAHs) raised the issue of safety with aberrant consumption of seafoods. Seafood choices that are very low in mercury include: salmon, sardines, pollock, flounders, cod, tilapia, shrimp, oysters, clams, scallops and crab. The U.S. Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) have developed directions to help consumers minimize risks that could be associated with several pollutants (specially mercury) in seafood.
Calculating the modes of cylindrical shell, then embed them into ideal perfect cylindrical pressure-resistant shell as the initial geometric imperfections to form the modal. According to the characteristics of each mode, the first 30 modes can be classified into four types, and it is found that the mode of the first type is the worst defect form. By calculation, the cylinder shell has the minimum ultimate strength when the 23rd mode happened. The sensitivity analysis of cylindrical shells with initial geometric defects shows that the critical buckling load has approximate linear relationship with different thickness radius ratio and defect amplitude. Six cylindrical shells of different materials are selected for research, and it is found that although the modal orders of the worst geometric defects of various materials are not the same, they all belong to the first type of mode. The comparison showed that the 921 steel and 909 steel materials are economic.
Discussion on the Design of Cultural Commercial Complex—Taking a design of a cultural and commercial complex next to a university in Yichang as an example
As the social economy develops faster and faster, the functions of commercial complex buildings become more and more diverse. It is not only a place to shop, but also a place to gather a place of popularity. Therefore, in addition to providing a shopping place, it also has the function of providing a gathering place for leisure and entertainment, and can become a landmark building of a city. Therefore, we hope that through the analysis of the design features of this work, a complete and detailed architectural design idea for the design of such commercial complexes can be proposed.
Nanometer zero-valent iron (nZVI) technology is one of the hotspot in environmental science, according to its huge surface area and high reactivity for the heavy metals, halogenated organic matter. However, as a result of a single nZVI problems easy to reunite and oxidized effect of nZVI reactivity, reduction of pollutant removal effect, the modification of nanometer zero-valent iron is a hotspot of nZVI technology this paper mainly discusses the conventional physical and chemical preparation methods of nanometer zero-valent iron and modified nano zero-valent iron technology are summarized, the future research emphases of nZVI technology are prospected.
Analyze the knowledge structure and frontier research hotspots in the field of supply chain risk management research, and study the overall research trends in this field. Using the knowledge mapping software tools VOSviewer and Sci2 Tool, based on the articles published on the WoS core database from 1997 to 2018, systematic analysis of the development trend of supply chain risk management research. Come to the following conclusion: 1.Supply chain risk management research will become more and more “hot”; 2.Supply chain risk management research was mainly distributed in five areas:“quantitative model of supply chain risk management”, “Lean closed-loop supply chain”, “Supply uncertainty”and“Green Supply Chain” and “Equity risk”; 3.The three key words of “Sustainability”, “Emerging Economy”, “Big Data” and “Supply Chain Finance”will evolve into research hotspots in the field of supply chain risk management in the future. The research results reveal the research hotspots and frontier research topics in the field of supply chain risk management.