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To evaluate the influence of water content on the hard coal dynamic behavior, the dynamic tensile properties of saturated coal Brazilian disk (BD) samples were studied using a split Hopkinson pressure bar system, and dry samples were also tested as a control group. In the range of impact speeds studied, the tensile strength of the saturated coal is lower than that of the dry specimen. A synchronized triggering high-speed camera was used to monitor the deformation and failure process of dry and saturated coal samples, allowing analysis of the failure stages and mechanism of dynamic BD test, the broken mode was classified into three types, which can be classified into unilateral tensile failure, bilateral or multilateral tensile failure, and shear failure. Finally, fragments smaller than 5 mm in diameter were statistically analyzed. There is less debris in range of 0−5.0 mm for the saturated coal sample than for the dry coal. This study provides some information about the dynamic response of the hard coal for the relevant practical engineering.

There is high demand for roadway support in coal mines for the swelling soft rocks. As high strength steel sets can be taken as an effective alternative to control large deformation in this type of rocks, based on an original set, three new sets, including a floor beam set, a roof and floor beams set, and a roof and floor beams and braces set, are proposed in this research. In order to examine the strengths of new sets, four scaled sets of one original set, and three new sets, have been manufactured and tested in loading experiments. Results indicated that three new sets all exhibited higher strength than the original set. In experiments, the roof beam in set plays a significant effect on top arch strengthening, while the floor beam plays significant effect on bottom arch strengthening. The maximum bearing capacity and stiffness of the top arch with roof beam are increased to 1.63 times and 3.06 times of those in the original set, and the maximum bearing capacity and stiffness of the bottom arch with floor beam are increased to 1.44 times and 3.55 times of those in original set. Based on the roof and floor beams, two more braces in the bottom arch also play a significant effect in bottom corners strengthening, but extra braces play little role in top arch strengthening. These new sets provide more choices for roadway support in swelling soft rocks.

This study aimed to characterize spatial/temporal variations of ambient volatile organic compounds (VOCs) using a community-scale monitoring approach and identify the main sources of concern in Paterson, NJ, an urban area with mixed sources of VOCs. VOC samples were simultaneously collected from three local source-dominated (i.e., commercial, industrial, and mobile) sites in Paterson and one background site in Chester, NJ (located ∼58 km southwest of Paterson). Samples were collected using the EPA TO-15 method from midnight to midnight, one in every sixth day over one year. Among the 60 analyzed VOCs, ten VOCs (acetylene, benzene, dichloromethane, ethylbenzene, methyl ethyl ketone, styrene, toluene, m,p-xylene, o-xylene, and p-dichlorobenzene) were selected to examine their spatial/temporal variations. All of the 10 VOCs in Paterson were significantly higher than the background site (p

Abstract: This paper studies insecure factors of fully-mechanized top coal mining in “three soft” large inclined angle working face, which have impacted the normal generation badly, including rib spalling, roof fall and equipment slide, etc. Based on engineering practice of Du-Jiacun 1201 working face, the theory model of coal wall and supports force are analyzed, and protective measures are also put forward. Findings of the study provide technical support for coal mining efficiently and securely, and reference for the similar geological conditions. [Copyright &y& Elsevier]

Ambient measurement and microenvironmental modeling were compared with personal measurement in Beijing, China to evaluate their capacity to determine personal exposure to PM2.5. The comparison showed the association was insignificant between ambient and personal concentrations, but was significant between modeled and personal concentrations. The association between ambient and personal concentrations was improved for non-smoking dormitories, on heavily polluted days and on weekdays. The median difference was 41% between ambient and personal concentrations and 17% between modeled and personal concentrations. The factors affecting the association and agreement between methods were indoor sources and ubiquitous “personal cloud”. [ABSTRACT FROM AUTHOR]

The article focuses on polycyclic aromatic hydrocarbon (PAH) assessment in Paterson, New Jersey. Concentrations of PAH in ambient air particulate matter that is equal or less than 10 micrometer in aerodynamic diameter was derived from the Urban Community Air Toxics Monitoring Project, which was done from November 2005- December 2006. In the analysis of the diagnostic ratios of PAH isomers, it was found that diesel-powered vehicles were responsible for higher concentrations of PAH.

The article discusses the spatial/temporal variations of particulate matter in Paterson, New Jersey, which is a mixed land-use community with industrial, commercial and residential lands. Three monitoring sites was chosen within the community and from November 18, 2005 - December 20, 2006, field sampling was done. The sampling revealed that there was a higher concentration of particulate matter in Pasterson compared to Chester due to presence of air pollutants in the area.