Analysis of failure mode and deformation evolution characteristics of slopes under the influence of highwall mining

The slope has the typical deformation failure and instability characteristics under the interaction of natural and human factors which has been given a lot of attention in geotechnical and mining engineering. During highwall mining, in particular, deformation evolution characteristics and failure mode are more complex under dual influence of open pit mine and underground mine. Physical modelling is an important means to study the characteristics and behavior of deformation and evolution of various types of rock and soil mass, and it is also an important supplement to the field study of large-scale rock and soil mass. It is widely used in mines and geotechnical engineering. The determination of the material used for physical modeling is the foundation and key links of research. Therefore, the article firstly selected river sand/aggregate, lime and gypsum/cemented material as the experimental materials through the relevant literature review and based on the principle of economic and convenience, and adopted two proportioning schemes to make standard specimens. The uniaxial compression test was carried out to compare and analyze the strength of the original rock, and it was determined that the scheme 2 could be used as the research scaling number of the physical modelling; Secondly, on the basis of determining the material proportion, the physical and structural model of highwall mining is established, and the analysis shows that the evolution characteristics of slope deformation and failure in the process of highwall mining can be divided into superficial transformation stage, structural transformation stage and aging deformation stage, the deformed and damaged rock mass can be divided into “vertical three zones”, namely caved zone, fractured zone and continuous bending zone. According to the length of the panel, the coal seam can be divided into three stages: initial stage, middle stage and final stage. The lower coal seam can be divided into two stages: the initial stage and the final stage. The evolution of the slope rock mass due to the extraction of the upper coal seam to the stopping line is characterized by the formation of subsidence faded areas along the center of the goaf to both sides, and finally a symmetrical distribution of semi-“pyramid” shape is formed. The rock mass that is deformed and damaged due to the extraction of the lower seam to the mining stop line is in a semi-curve-like shape; Finally, based on the analysis of physical modelling and field monitoring, it is concluded that when the upper coal seam of the highwall coal seam is mined to about 120 m, the slope shows a slight instability. When the lower coal seam is mined to about 120 m, the goaf between the upper and lower coal seams is connected, and the instability is intensified until the mining reaches the stopping line. In the upper part of the slope, 1400 step forms a local collapse instability zone pointing to the open-pit, while the rest of the step are anti-dip instability pointing to the goaf

Aerosol Jet Printing of Graphene and Carbon Nanotube Patterns on Realistically Rugged Substrates

Direct-write additive manufacturing of graphene and carbon nanotube (CNT) patterns by aerosol jet printing (AJP) is promising for the creation of thermal and electrical interconnects in (opto)electronics. In realistic application scenarios, this however often requires deposition of graphene and CNT patterns on rugged substrates such as, for example, roughly machined and surface oxidized metal block heat sinks. Most AJP of graphene/CNT patterns has thus far however concentrated on flat wafer-or foil type substrates. Here, we demonstrate AJP of graphene and single walled CNT (SWCNT) patterns on realistically rugged plasma electrolytic-oxidized (PEO) Al blocks, which are promising heat sink materials. We show that AJP on the rugged substrates offers line resolution of down to similar to 40 mu m width for single AJP passes, however, at the cost of noncomplete substrate coverage including noncovered mu m-sized pores in the PEO Al blocks. With multiple AJP passes, full coverage including coverage of the pores is, however, readily achieved. Comparing archetypical aqueous and organic graphene and SWCNT inks, we show that the choice of the ink system drastically influences the nanocarbon AJP parameter window, deposit microstructure including crystalline quality, compactness of deposit, and inter/intrapass layer adhesion for multiple passes. Simple electrical characterization indicates aqueous graphene inks as the most promising choice for AJP-deposited electrical interconnect applications. Our parameter space screening thereby forms a framework for rational process development for graphene and SWCNT AJP on application-relevant, rugged substrates

Improved low concentration gas detection system based on intracavity fiber laser

The improvement of a low concentration gas detection system based on the intracavity fiber laser is proposed in this paper. The sensitivity of the system is deduced based on Lambert–Beer law. The optimized system was established with the gas cell made elaborately. In order to apply the wavelength sweeping technique, the fiber Bragg grating reflector was substituted by the wavelength independent Faraday rotation reflector. The sensitivity of the system for acetylene detection is reduced to less than 100 ppm by using the average of three absorption spectra. The acetylene detection coefficients of variation with different concentrations are measured. The gas measurement system is validated to detect low concentration gas effectively

Fabrication of Hierarchical Co/MgO Catalyst for Enhanced CO2 Reforming of CH4 in a Fluidized-Bed Reactor

This work reports facile fabrication of fluidizable hierarchical Co-MgO particles with high dispersion of Co nanoparticles (NPs) and high surface oxygen vacancies for matching with the fluidized-bed reactor. The hierarchical Co-MgO catalyst exhibits higher activity and thermal stability for CH4-CO2 reforming than the conventional impregnation Co/MgO catalyst. The enhanced prevention of Co NPs sintering of the hierarchical Co-MgO catalyst is attributed to the multilayer structure and the exposed MgO (111) face, which creates high surface oxygen vacancies, induces high Co dispersion to restrain Co NPs sintering, and supplies high resistance to graphite carbon deposition. A formation mechanism for the hierarchical MgO structure is also proposed. This formation of incomplete rhombohedron MgO particles with an exposed octahedral MgO (111) face is attributed to the electrostatic interaction of OH-. The proposed approach to improving catalytic activity by creation of hierarchical MgO particles can be expanded to other metal oxide catalysts. (c) 2018 American Institute of Chemical Engineers AIChE J, 65: 120-131, 201

Optimal scheduling of thermal-photovoltaic power generation system considering carbon emission

Increasing the proportion of clean energy is an inevitable trend of high-quality energy development. While enjoying the benefits of clean energy, traditional fossil energy enterprises face great challenges. In this study, coal power and photovoltaic power are selected as examples for analysis. Considering coal consumption, carbon emission, unit ramp conditions and photovoltaic abandonment, a comprehensive income model containing thermal power and photovoltaic power generation is proposed. The objective function of maximizing earnings is established and solved by genetic algorithm. The results show that the overall benefit will increase if the proportion of photovoltaic does not increase blindly. The unreasonable ratio of thermal and photovoltaic power and the imbalance of supply and consumption will lead to the decline of economic benefits and the increase of coal consumption and carbon emission. In the case of a high proportion of clean energy penetration, on the one hand, traditional power plants should be responsible for ensuring the instability of electricity output when the photovoltaic is weak, on the other hand, they need to give up some of the supply proportion when clean power is at a high output state. Therefore, while increasing the proportion of clean energy, it is necessary to improve the speed of load adjustment, the depth of peak regulation and the efficiency of low load work in traditional power plants to ensure the healthy development of new energy

Novel hierarchical Ni/MgO catalyst for highly efficient CO methanation in a fluidized bed reactor

A facile synthesis of the hierarchical Ni/MgO catalyst is reported, with extremely fine dispersion of Ni nanoparticles (NPs) and high surface oxygen mobility. The hierarchical Ni/MgO catalyst exhibits higher activity for CH4 formation than that prepared by the impregnation method. The enhanced activity and thermal stability of the hierarchical Ni/MgO catalyst is attributed to hierarchical MgO particles with a multilayer structure and high surface oxygen mobility. This induces better metal-support interactions, high Ni dispersion to prevent Ni NPs sintering, and the high surface oxygen mobility provides a high resistance to carbon deposition. Compared to the impregnated Ni/MgO catalyst, the hierarchical Ni/MgO catalyst exhibits a better fluidization quality and a higher attrition-resistance in a fluidized-bed reactor. This approach to improve the catalytic activity by creation of hierarchical Ni/MgO particles is encouraging for the design of novel catalysts for synthetic natural gas production, especially from the perspective of matching catalysts with fluidized-bed reactors. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 2141-2152, 2017</p

The Aborted Microspores (AMS)-Like Gene Is Required for Anther and Microspore Development in Pepper (Capsicum annuum L.)

Pepper (Capsicum annuum L.) is an economically important vegetable crop worldwide. Although many genes associated with anther and pollen development have been identified, little is known about the mechanism of pollen abortion in pepper. Here, we identified and isolated two putative aborted microspore (AMS) isoforms from pepper flowers: CaAMS1 and CaAMS2. Sequence analysis showed that CaAMS2 was generated by retention of the fourth intron in CaAMS1 pre-mRNA. CaAMS1 encodes a putative protein with a basic helix-loop-helix (bHLH) domain belonging to the MYC subfamily of bHLH transcription factors, and it is localized to the nucleus. Truncated CaAMS2-1 and CaAMS2-2 are produced by alternative splicing. Quantitative real-time PCR analysis showed that CaAMS (referred to CaAMS1 and CaAMS2-2) was preferentially expressed in stamens and its expression level gradually decreases with flower development. RNA in situ hybridization analysis showed that CaAMS is strongly expressed in the tapetum at the tetrad and uninucleate stages. Downregulation of CaAMS led to partial shortened filaments, shriveled, indehiscent stamens and abortive pollens in pepper flowers. Several genes involved in pollen exine formation were downregulated in defective CaAMS-silenced anthers. Thus, CaAMS seems to play an important role in pepper tapetum and pollen development by regulating a complex genetic network