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Type Ⅱ codes over finite rings

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Science China Mathematics 2010年第1期53卷 203-212页

作者： dougherty Steven T Department of Mathematics University of Scranton ScrantonPA 18510 USA

In this paper,we generalize the concept of Type Ⅱ codes to arbitrary finite rings. We focus on Type Ⅱ codes over finite chain rings and use the Chinese Remainder Theorem on these codes to study Type Ⅱ codes over pr... 详细信息

关键词： finite principal ideal rings finite chain rings self-dual codes Type Ⅱ codes

Evaluation of fiber optic methane sensor using a smoke chamber

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International Journal of Mining Science and Technology 2018年第6期28卷 969-974页

作者： Mingming Li Thomas Dubaniewicz Heather dougherty Jim Addis National Institute for Occupational Safety and Health Pittsburgh Mining Research Division

This report presents the results of experiments to evaluate a prototype fiber optic methane monitor exposed to smoke using a smoke chamber to simulate atmospheric conditions in an underground coal mine after a fire or explosion. The experiments were conducted using test fires of different combustible sources commonly found in mines —douglas-fir wood, SBR belt, and Pittsburgh seam coal. The experiments were designed to assess the response of the fiber optic methane sensor to different contaminants,different contaminant levels and different contaminant durations produced from the test fires. Since the prototype methane monitor detects methane by measuring absorption at a specific wavelength, optical power at the absorption wavelength(1650 nm) was measured as a function of smoke concentration and duration. The other sensor response parameter-methane response times-were measured between smoke tests to assess the impact of soot accumulation on the sensor. Results indicate that the sensor screen effectively prevented smoke from obscuring the optical beam within the sensor head, with minimal impact on the system optical power budget. Methane response times increased with smoke exposure duration, attributed to soot loading on the protective screen.

关键词： Fiber optic Methane sensor Fires Optical power Response time

CYCLIC CODES OVER FORMAL POWER SERIES RINGS

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Acta Mathematica Scientia 2011年第1期31卷 331-343页

作者： dougherty Steven T. 刘宏伟 Department of Mathematics University of Scranton Department of Mathematics Huazhong Normal University

In this article, cyclic codes and negacyclic codes over formal power series rings are studied. The structure of cyclic codes over this class of rings is given, and the relationship between these codes and cyclic codes over finite chain rings is obtained. Using an isomorphism between cyclic and negacyclic codes over formal power series rings, the structure of negacyclic codes over the formal power series rings is obtained.

关键词： Finite chain rings cyclic codes negacyclic codes γ-adic codes

Influence of longwall mining on the stability of gas wells in chain pillars

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International Journal of Mining Science and Technology 2020年第1期30卷 3-9页

作者： Peter Zhang Heather dougherty Daniel Su Jack Trackemas Berk Tulu CDC NIOSH Pittsburgh Mining Research Division(PMRD)PittsburghPA 15236USA Department of Mining Engineering West Virginia UniversityMorgantownWV 26505USA

Longwall mining has a significant influence on gas wells located within longwall chain *** subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well *** the gas well casings are compromised or ruptured,natural gas could migrate into the mine workings,potentially causing a fire or *** the current safety regulations,the gas wells in the chain pillars have to be either plugged or protected by adequate coal *** current regulations for gas well pillar design are based on the 1957 Pennsylvania gas well pillar *** study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the *** the guidelines were developed for room-andpillar mining under shallow cover,they are no longer applicable to modern longwall coal mining,particularly,under deep *** well casing of failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 *** study,conducted by the National Institute for Occupational Safety and Health(NIOSH),presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh Coal *** study results indicate that overburden depth and pillar size are not the only determining factors for gas well *** other important factors include subsurface ground movement,overburden geology,weak floor,as well as the type of the construction of gas *** modeling was used to model abutment pressure,subsurface deformations,and the response of gas well *** study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above,within,and below the chain pillars,and the potential location and modes of gas well failures,thereby providing a more quantifiable approach to assess the stability of the gas wells in l

关键词： Longwall mining Gas well Chain pillar Casing stability

Analysis of gateroad stability at two longwall mines based on field monitoring results and numerical model analysis

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International Journal of Mining Science and Technology 2019年第1期29卷 35-43页

作者： Gabriel S.Esterhuizen David F.Gearhart Ted Klemetti Heather dougherty Mark van Dyke National Institute for Occupational Safety and Health

Coal mine longwall gateroads are subject to changing loading conditions induced by the advancing longwall face. The ground response and support requirements are closely related to the magnitude and orientation of the stress changes, as well as the local geology. This paper presents the monitoring results of gateroad response and support performance at two longwall mines at a 180-m and 600-m depth of *** the first mine, a three-entry gateroad layout was used. The second mine used a four-entry, yieldabutment-yield gateroad pillar system. Local ground deformation and support response were monitored at both sites. The monitoring period started during the development stage and continued during first panel retreat and up to second panel retreat. The two data sets were used to compare the response of the entries in two very different geotechnical settings and different gateroad layouts. The monitoring results were used to validate numerical models that simulate the loading conditions and entry response for these widely differing conditions. The validated models were used to compare the load path and ground response at the two mines. This paper demonstrates the potential for numerical models to assist mine engineers in optimizing longwall layouts and gateroad support systems.

关键词： Coal mining Longwall Gateroad Support Numerical models

Assessing support alternatives for longwall gateroads subject to changing stress

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International Journal of Mining Science and Technology 2021年第1期31卷 103-110页

作者： Gabriel S.Esterhuizen I.Berk Tulu Dave F.Gearhart Heather dougherty Mark Van Dyke National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA West Virginia University MorgantownWV 26506USA

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted *** stress changes can result in significant deformation of the entries that may include roof sag,rib dilation,and floor *** operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall *** paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support *** research included monitoring of ground and support interaction at several operating longwall mines in the U.S.,analysis and calibration of numerical models that adequately represent the bedded rock mass,and observation of the support systems and their response to changes in *** models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic *** research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress *** information is then used to assess the ability of support systems to maintain the stability of the *** application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof *** method is shown to produce realistic estimates of gateroad entry stability and support performance,allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

关键词： Longwall Gateroad Support design Coal Standing support

Percutaneous cervical carotid artery access with stenting of the left internal carotid artery in an elderly patient

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Journal of Geriatric Cardiology 2007年第2期4卷 111-114页

作者： Matthew O'Steen Kathy dougherty Neil E. Strickman Division of Cardiology Baylor College of Medicine at St. Luke's Episcopal Hospital and the Texas Heart Institute Houston TX

To describe the successful endovascular treatment in a nonagenarian with symptomatic internal carotid artery stenosis using direct carotid artery access. An independent 98 year-old man was admitted to our hospital for symptoms of progressive weakness with disorientation and dysphasia. Carotid Duplex ultrasonography was performed which revealed a totally occluded right internal carotid artery and high grade stenosis of the left internal carotid artery by velocities of 608/240 cm/sec. The patient refused surgical endarterectomy and thus he was referred for carotid artery stenting. Using the femoral artery approach and multiple catheter techniques, access to the common carotid artery could not be accomplished safely. The procedure was aborted and he was therefore brought back to the catheterization laboratory the following day for direct carotid access. Carotid artery stenting was accomplished by using of a 6F sheath percutaneously in the left common carotid, cerebral protection device (CPD) and a Nitinol stent. The patient was discharged the following day without complications. At 14 months follow-up the patient is functional and independent without recurrence of symptoms. Carotid artery stenting via direct access can be accomplished in patients when the femoral artery approach is anatomically prohibitive. In this case of advanced age and the patient’s refusal for surgery, direct carotid access was his only option.

关键词： left Percutaneous cervical carotid artery access with stenting of the left internal carotid artery in an elderly patient

Longwall mining,shale gas production,and underground miner safety and health

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International Journal of Mining Science and Technology 2021年第3期31卷 523-529页

作者： D.W.H.Su P.Zhang H.dougherty M.Van Dyke R.Kimutis Center for Disease Control and Prevention(CDC) National Institute for Occupational Safety and Health(NIOSH)Pittsburgh Mining Research Division(PMRD)PittsburghPA 15236USA

This paper presents the results of a unique study conducted by the National Institute for Occupational Safety and Health(NIOSH)from 2016 to 2019 to evaluate the effects of longwall-induced subsurface deformations on shale gas well casing integrity and underground miner safety and *** both deep-cover and shallow-cover instrumentation sites,surface subsidence measurements,subsurface inplace inclinometer measurements,and underground pillar pressure measurements were conducted as longwall panels were *** of the deep-cover and shallow-cover test site results with those from a similar study under medium cover reveal an interesting longwall-induced response *** shallow and medium covers,measured horizontal displacements within the abutment pillar are one order of magnitude higher than those measured under deep *** the other hand,measured vertical compressions under deep cover are one order of magnitude higher than those under shallow and medium ***,FLAC3 Dsimulations of the casings indicate that,in all three cases,the P-110 production casings remain intact under longwall-induced deformations and compressions,which has serious implications for future mine design in areas where shale gas wells have been drilled ahead of mining.

关键词： Longwall Mining Coal Gas Miner Safety Health

Preoperative virtual video visits only:a convenient option that should be offered to caregivers beyond the pandemic

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World Journal of Pediatric Surgery 2022年第3期5卷 169-175页

作者： Danielle dougherty Allison R Thompson Karen Elizabeth Speck Erin E Perrone Section of Pediatric Surgery Department of SurgeryUniversity of Michigan Health SystemAnn ArborMichiganUSA Department of Health Behavior and Health Education University of Michigan School of Public HealthAnn ArborMIUSA

Objective During the COVID-19 pandemic,our group implemented preoperative video visits(VVs)to limit physical *** aim of this study was to determine caregivers’and providers’perceptions of this practice and to determine feasibility for *** All patients who had only a preoperative VV prior to an elective surgery were identified from March-October ***,surgeons,and clinic staff were surveyed about their *** Thirty-four preoperative VVs were followed by an elective surgery without a preceding in-person *** the 31 caregiver surveys completed,the majority strongly agreed that the VV was more convenient(87%,n=27).Eighty-one percent(n=25)strongly agreed or agreed that the VV saved them ***-four percent(n=29)strongly agreed or agreed that they would choose the VV option *** saved an average travel distance of 60.3 miles one way(range 6.1-480).Of the 13/17 providers who responded,77%(n=10)expressed that the practice should *** Virtual health became a necessity during the pandemic,and caregivers were overwhelmingly *** VVs as an option beyond the pandemic may be a reasonable and effective way to help eliminate some of the hurdles that impede healthcare-seeking behavior and should be offered.

关键词： convenient beyond eliminate