| 1 | Microseismic monitoring and analysis of induced seismicity source mechanisms in a retreating room and pillar coal mine in the Eastern United States显示文摘A microseismic monitoring system was installed in an underground room and pillar coal mine in the Eastern United States to analyze the occurrence and characteristics of induced seismicity during the retreat of two panels in the mine.This study is the first microseismic monitoring effort at an underground coal mine in nearly 30 years.During the retreat of the first panel,an array of eight uniaxial geophones,installed 10 ft.into the roof,recorded events and their magnitudes.The second panel was monitored using an array of twelve uniaxial geophones and two triaxial geophones,also installed 10 ft.into the roof.Comparing the results of these studies,it has been found that the magnitude of seismic events is minimally affected by immediate roof geology or depth of cover.However,it was observed in both studies that the rate at which seismic events occurred did vary with changing roof geology and depth of cover.Using the seismic data from the second panel retreat,focal mechanism solutions were generated for 50 hand-picked events in order to determine if the failure was in compression,tension,or shear.Results of the focal mechanism solutions show that stress relief resulting in dilational events occurs at significant depths,150-200 m in this case,beneath the active mining face. | Morgen R.Leake William J.Conrad Erik C.Westman Setareh Ghaychi Afrouz Ryan J.Molka | 2017 | Underground Space2017，2，2： | 1 |
| 4 | AGRONOMIC AND ENVIRONMENTAL BENEFITS OF REINTRODUCING HERB-AND LEGUME-RICH MULTISPECIES LEYS INTO ARABLE ROTATIONS:A REVIEW显示文摘Agricultural intensification and the subsequent decline of mixed farming systems has led to an increase in continuous cropping with only a few fallow or break years,undermining global soil health.Arable-ley rotations incorporating temporary pastures(leys) lasting 1–4 years may alleviate soil degradation by building soil fertility and improving soil structure.However,the majority of previous research on arable-ley rotations has utilized either grass or grassclover leys within ungrazed systems.Multispecies leys,containing a mix of grasses,legumes,and herbs,are rapidly gaining popularity due to their promotion in agri-environment schemes and potential to deliver greater ecosystem services than conventional grass or grass-clover leys.Livestock grazing in arable-ley rotations may increase the economic resilience of these systems,despite limited research of the effects of multispecies leys on ruminant health and greenhouse gas emissions.This review aims to evaluate previous research on multispecies leys,highlighting areas for future research and the potential benefits and disbenefits on soil quality and livestock productivity.The botanical composition of multispecies leys is crucial,as legumes,deep rooted perennial plants(e.g.,Onobrychis viciifolia and Cichorium intybus) and herbs(e.g.,Plantago lanceolata) can increase soil carbon,improve soil structure,reduce nitrogen fertilizer requirements,and promote the recovery of soil fauna(e.g.,earthworms) in degraded arable soils while delivering additional environmental benefits(e.g.,biological nitrification inhibition and enteric methane reduction).Multispecies leys have the potential to deliver biologically driven regenerative agriculture,but more long-term research is needed to underpin evidence-based policy and farmer guidance. | Emily C.COOLEDGE David R.CHADWICK Lydia M.J.SMITH Jonathan R.LEAKE Davey L.JONES | 2022 | Frontiers of Agricultural Science and Engineering2022，9，2： | 0 |
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