Relationship of Seam Smoldering Velocity and Oxygen Volume Fraction Gradient in Roadway

AbstractSmoldering is an oxygen control reaction and its velocity is determined by oxygen supplying rate. Oxygen volume fraction gradient was used to characterize oxygen supplying rate in roadway according to situation that the velocity of wind flowing is very low during smoldering in roadway. Relationship of smoldering velocity and oxygen volume fraction gradient in roadway during lignite smoldering was researched in experiment drawing support of seam smoldering simulating experiment device in roadway and one-variable linear regression technology was used to establish the relation equation of smoldering velocity and oxygen volume fraction gradient in roadway when lignite was smoldering. This relation equation showed that smoldering velocity and oxygen volume fraction gradient took on linear increasing relationship in roadway during lignite smoldering

Experimental Research on Shear Ductility of Regional Confined Concrete Beam

In efforts to study the shear ductility of regional confined concrete beam, 5 reinforced concrete beams were tested to examine its shear performance. These beams has the same shear span ratio, concrete strength, different ratios of tension reinforcement and shapes of stirrup. The purpose of the test is studying the effects of stirrup shape and tension reinforcement ratio on failure mode and shear ductility. The test shows that the regional confined part can be used as an independent part and the rest of the beam is good to work together so that the ductility of the beam is more one time higher than that of the normal confined concrete beam. The related laws of the effect of tension reinforcement ratio and stirrup shapes on beam's shear ductility were founde

Experimental Research on Shear Ductility of Regional Confined Concrete Beam

In efforts to study the shear ductility of regional confined concrete beam, 5 reinforced concrete beams were tested to examine its shear performance. These beams has the same shear span ratio, concrete strength, different ratios of tension reinforcement and shapes of stirrup. The purpose of the test is studying the effects of stirrup shape and tension reinforcement ratio on failure mode and shear ductility. The test shows that the regional confined part can be used as an independent part and the rest of the beam is good to work together so that the ductility of the beam is more one time higher than that of the normal confined concrete beam. The related laws of the effect of tension reinforcement ratio and stirrup shapes on beam's shear ductility were founde

Thermal Stability and Flame Retardancy of Rigid Polyurethane Foam Composites Filled with Phase-Change Microcapsule

The flammability of rigid polyurethane foam (RPUF) limits its application. A new type of chitosan phase-change microcapsule (CS/PCM) was successfully prepared by the condensation method with chitosan and gum acacia as the wall material and paraffin as the core material. CS/PCM was introduced into RPUF composite material as filler to improve the thermal and flame-retardant properties of polyurethane. The morphology, structure, thermal properties and flame retardancy of the materials were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) and cone calorimetry. It is found that when the CS/PCM content is 30 wt%, the latent heat of phase transition of RPUF-30 is 12.308 J/g, the limiting oxygen index (LOI) is 26.1% and the fire risk is reduced. The flame-retardant mechanism shows that the barrier effect provided by chitosan plays an important role in effectively blocking the transfer of heat and combustible gas, and improving the flame-retardant property of the composite. This paper provides a new idea for the application of CS/PCM in RPUF

Experimental Research on Shear Ductility of Regional Confined Concrete Beam

In efforts to study the shear ductility of regional confined concrete beam, 5 reinforced concrete beams were tested to examine its shear performance. These beams has the same shear span ratio, concrete strength, different ratios of tension reinforcement and shapes of stirrup. The purpose of the test is studying the effects of stirrup shape and tension reinforcement ratio on failure mode and shear ductility. The test shows that the regional confined part can be used as an independent part and the rest of the beam is good to work together so that the ductility of the beam is more one time higher than that of the normal confined concrete beam. The related laws of the effect of tension reinforcement ratio and stirrup shapes on beam's shear ductility were founde

Research on safety evaluation of bolt support based on analytic hierarchy process-entropy weight method

To evaluate the safety performance of bolt support scientifically, the factors affecting bolt support are systematically analyzed, the comprehensive evaluation index system is established from four aspects: support parameters, quality of bolt and fittings, construction management and monitoring level, and the safety evaluation model of bolt support is constructed; the AHP and entropy weight method are combined to determine the weight of each index, and the safety evaluation system of bolt support based on AHPentropy weight method is established and its application program is developed. The safety evaluation method and application program proposed in this paper are applied to the safety evaluation of bolt support in a coal mine in Shanxi Province, and the results are in agreement with the actual situation. This article studies the correlation

Evolutionary Game Research on Symmetry of Workers’ Behavior in Coal Mine Enterprises

Statistics show that humans’ unsafe behaviors are the main cause of accidents. Because of the asymmetry of game benefits between managers and coal miners, the stability of workers’ behaviors is affected and unsafe behaviors are produced. In this paper, the symmetry of the behavior benefits of coal mine workers is studied, using game theory. In order to observe the dynamic game evolution process of behavioral stability, the paper establishes a system dynamics (SD) model and simulates it. The SD simulation results show that with the continuation of the game, when the benefits for safety managers and workers are asymmetric and the safety manager’s safety inspection benefits are less than the non-inspection benefits, the manager may not conduct safety inspections, which poses a great hidden danger to safety production. Through dynamic incentives to regulate the symmetry of income of coal mine safety managers and coal mine workers, the purpose of enhancing the stability of safety behavior is achieved. The research results of the paper have been successfully applied to coal mine enterprises

Antibacterial and Antifungal Compounds from Marine Fungi

This paper reviews 116 new compounds with antifungal or antibacterial activities as well as 169 other known antimicrobial compounds, with a specific focus on January 2010 through March 2015. Furthermore, the phylogeny of the fungi producing these antibacterial or antifungal compounds was analyzed. The new methods used to isolate marine fungi that possess antibacterial or antifungal activities as well as the relationship between structure and activity are shown in this review

Aperture scalable liquid crystal optically duplicated array of phased array

To achieve non-mechanical laser beam steering in the scenario of long distance propagation such as free-space laser communication between satellites, large aperture size is an inevitable issue to be considered to narrow the divergence angle of the output beam. Liquid crystal optical phased array, to be one of the solutions of non-mechanical beam steering, has already shown its obvious potential to achieve a relative large aperture on the order of centimeter. To achieve even larger, its driving matrix becomes squared larger. In this paper, we proposed a novel architecture to realize an optical phased array with a scalable aperture. Meanwhile the driving matrix is almost not increased. It provides the feature of a cascade system with a device of spatial phased modulation and an array of duplicating units. Each unit of the duplicating array is consist of a polarization beam splitter and a half wave plate to have the same output optical field distribution as the input beam whose phase front is modulated by a small size spatial modulator. Not only the property of beam deflection is numerically simulated and experimentally verified, but also the property of divergence angle compression and grating lobes limitation are evaluated. Meanwhile, due to the high precision of the experimental alignment, the non-mechanical beam deflection property is still maintained no matter how many the duplicated unit number is. The relative standard derivation steering error is 0.025