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Effect of longwall-induced subsurface deformations on shale gas well casing stability under deep covers

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International Journal of Mining Science and Technology 2019年第1期29卷 3-8页

作者： Daniel W.H.Su Peter Zhang Mark Van Dyke todd Minoski Center for Disease Control and Prevention(CDC) National Institute for Occupational Safety and Health(NIOSH)Pittsburgh Mining Research Division(PMRD)

This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D *** from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.

关键词： Longwall Deformations Shale gas wells Casing Safety and health

ERCP for the treatment of bile leak after partial hepatectomy and fenestration for symptomatic polycystic liver disease

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World Journal of Gastroenterology 2012年第28期18卷 3705-3709页

作者： Nayantara Coelho-Prabhu David M Nagorney todd H Baron Mayo Clinic College of Medicine Rochester MN 55905 United States

AIM: To describe endoscopic treatment of bile leaks in these patients and to identify risk factors in these patients which can predict the development of bile leaks. METHODS: Retrospective case-control study examining consecutive patients who underwent partial hepatectomy for polycystic liver disease (PLD) and developed a postoperative bile leak managed endoscopically over a ten year period. Each case was matched with two controls with PLD who did not develop a postoperative bile leak. RESULTS: Ten cases underwent partial hepatectomy with fenestration for symptoms including abdominal distention, pain and nausea. Endoscopic retrograde cholangiopancreatography (ERCP) showed anatomic abnormalities in 1 case. A biliary sphincterotomy was performed in 4 cases. A plastic biliary stent was placed with the proximal end at the site of the leak in 9 cases; in 1 case two stents were placed. The overall success rate of ERCP to manage the leak was 90%. There were no significant differences in age, gender, comorbidities, duration of symptoms, history of previous surgery or type of surgery performed between cases and controls. CONCLUSION: ERCP with stent placement is safe and effective for management of post-hepatectomy bile leak in patients with PLD.

关键词： Polycystic liver Hepatectomy Bile leak Endoscopic retrograde cholangiopancreatography

A Comparative Study of Female Entrepreneurs in China and Australia:the Same Glass Ceiling to Shatter?

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A Comparative Study of Female Entrepreneurs in China and Aus...

作者： Caitlin todd 上海交通大学

学位级别：硕士

In the age of global initiatives citing the importance of entrepreneurship and innovation,countries that fail to embrace the potential of its female entrepreneurs are poised to lose out on the realisation of ideas,opportunities for trade and export and the creation of job *** purpose of this study is to examine the challenges experienced by female entrepreneurs in China and Australia,with a goal of discovering specific cultural based differences in their *** matter to the economic prosperity of a country,but underlying bias in the environments of different regions may play a role in constraining their *** is necessary to compare the experiences of female entrepreneurs in multiple environments to assess the extent that different socio-economic conditions have,and China and Australia with their dissimilar climates provide a relevant base for this comparison.A qualitative methodology conducted through interviews is used in this research to allow for a deeper understanding of human choices,emotions and *** human factors are incremental in understanding the potential cultural sways that are inherent to answering the research questions of this *** results show that female entrepreneurs in China and Australia face some unique challenges that are the results of certain cultural and traditional *** general,results show that gender is not a factor in terms of access to resources and favourable institutional environments,however certain country-level measures could be introduced to help bolster entrepreneurship in *** thesis seeks to contribute to existing literature on female entrepreneurship by giving an in-depth view of the personal experiences of a select group of female *** also seeks to contribute towards the creation of an entrepreneurial ecosystem that helps to foster the growth of female entrepreneurship through providing a suggestion as to the type of environment necessary to enc

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Interactions between background matching and disruptive colouration： Experiments using human predators and virtual crabs

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Current Zoology 2015年第4期61卷 718-728页

作者： Peter A. todd Huijia PHUA Kok Ben TOH Experimental Marine Ecology Laboratory Department of Biological Sciences National University of Singapore 14 Science Drive 4 Blk S3 #02-05 Singapore 117543

Interactions between disruptive colouration and the match between prey and background spot size were manipulated in two experiments that used time taken by human ＇predators＇ to find artificial prey （virtual crab morphs） against heterogeneous backgrounds as a measure of the their camouflage. Experiment 1, in which the spots and their placement imitated the arrangement on the crab Carcinus maenas, tested whether high and low contrast spots touching the body outline （disruptive ＇edge＇ morphs） made the artificial prey more difficult to detect than when the spots did not touch the outline （non-disruptive ＇inner＇ morphs） against three different backgrounds：＇small＇, ＇middle＇ and ＇large＇ spot size. In Experiment 2, the range of spot sizes and their positions （＇edge＇ and ＇inner＇） on the crab morphs were varied to determine the most effective combination against the ＇mid- dle＇ background. Altogether, 640 volunteers participated in these computer trials, representing a high degree of independent replication. All patterned morphs were significantly harder to detect than plain morphs, indicating that possessing at least some degree of background matching can provide camouflage. Both experiments demonstrated that various morphs, though not having the same spot sizes as the background, had similar or better survivorship as those with matching spot sizes--indicating that opti- mal camouflage did not come from background matching alone. In Experiment 2, edge-disrupted morphs consistently took longer to find than their non-disruptive counterparts. The relative effects of edge disruption, contrast, and background/prey spot size are clearly context-dependent, highlighting the complexity of prey concealment [Current Zoology 61 （4）： 718-728, 2015].

关键词： Background matching Camouflage Carcinus maenas Crypsis Disruptive colouration Predation

FunnelCloud:a cloud-based system for exploring tornado events

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International Journal of Digital Earth 2017年第10期10卷 1030-1054页

作者： Jie Lian Michael P.McGuire todd W.Moore Department of Computer and Information Sciences Towson UniversityTowsonMDUSA Department of Geography and Environmental Planning Towson UniversityTowsonMDUSA

Recent research has shown an increase in the number of extreme tornado outbreaks per *** characterization of the spatio-temporal pattern of tornado events is therefore a critical task in the analysis of meteorological ***,there are a large number of available meteorological datasets that can be used for such ***,much of these data are distributed across multiple websites and are not accessible in a central *** poses a significant challenge for a scientist who is interested in exploring meteorological patterns associated with tornado *** paper presents a novel system which uses cloud-based technology for integrating,storing,exploring,analyzing,and visualizing meteorological data associated with tornado *** system employs a novel NoSQL database schema and web services architecture for data integration and provides a user friendly interface that allows scientists to explore the spatio-temporal pattern of tornado ***,scientists can use this interface to analyze the relationship between different meteorological variables and properties of tornado outbreaks using a number of spatio-temporal statistical and data mining *** efficacy of the system is demonstrated on a use case centered on the analysis of climatic indicators of large spatio-temporally clustered tornado outbreaks.

关键词： tornado data warehouse cloud-based system NoSQL data integration spatio-temporal clustering web-mapping

Analysis of Oxides Formed on the Surface of the Alloy 690 in Hydrogenated Supercritical Water

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 774-781页

作者： Jin Gao Fa-rong Wan Guo-ping Cao Kumar Sridharan todd Allen School of Materials Science and Engineering University of Science and Technology Beijing Department of Materials Science and Engineering University of Wisconsin-Madison

The oxides formed on the surface of the alloy 690 in hydrogenated supercritical water at 400℃ for 1000 h were investigated using scanning electron microscopy,transmission electron microscopy,scanning transmission electron microscopy and energy-dispersive X-ray *** oxides on me surface of the alloy 690 exhibited multi-layer structure：an outer layer consisted of granular crystallites（NiO and NiFe_2O_4） and a compact inner layer（spinel and Cr_2O_3）.Chemical analysis indicated that the outer layer was enriched in nickel but depleted in chromium,whereas the inner layer was enriched in chromium and iron but depleted in *** inner layer was also characterized as layered structure by Fe-rich spinel on top of continuous Cr_2O_3 ***,Cr_2O_3 nodules were readily observed at the oxides/alloy interface.

关键词： Alloy 690 Supercritical water Oxides Corrosion

Successful endoscopic treatment of colonic gallstone ileus using electrohydraulic lithotripsy

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World Journal of Gastroenterology 2010年第12期16卷 1533-1536页

作者： Martin D Zielinski Lincoln E Ferreira todd H Baron Division of Trauma Critical Care and General Surgery Department of Medicine Federal University of Juiz de Fora Department of Gastroenterology and Hepatology

The surgical management of gallstone ileus is complex and potentially highly *** management requires enterolithotomy and is generally followed by fistula resection at a later *** have been reports of gallstone extraction using various endoscopic modalities to relieve the obstruction,however,to date,there has never been a published case of endoscopic stone extraction from the colon using electrohydraulic *** this report,we present the technique employed to successfully perform an electrohydraulic lithotripsy for removal of a large gallstone impacted in the sigmoid colon.A cavity was excavated in an obstructing 4.1 cm lamellated stone in the sigmoid colon using electrohydraulic lithotripsy.A screw stent retractor and stent extractor bored a larger lumen which allowed for guidewire advancement and stone fracture via serial pneumatic balloon *** stone fragments were *** lithotripsy is a safe and effective method to treat colonic obstruction in the setting of gallstone ileus.

关键词： Gallstone ileus Endoscopy Electrohydraulic lithotripsy Bowel obstruction Colon

Influence of varying bedding thickness of underclay on floor stability

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International Journal of Mining Science and Technology 2017年第3期27卷 517-523页

作者： Jessu Kashi Vishwanath Kostecki todd Ray Spearing Anthony John Spencer Zhang Jixiong Western Australia School of Mines Curtin University Kalgoorlie 6430 Australia Southern Illinois University Carhondale 62901 USA The State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Xuzhou 221116 China

The variation in bedding thickness of the weak immediate floor has long been a challenge in the lllinois basin coal mines when it comes to floor stability. The vertical thickness of the immediate floor is not constant throughout the mines and can vary over short horizontal distances. The biggest misconception from a design standpoint is to use the maximum or average thickness found from core logs taken from various locations on the mine property. The result of this practice is oversized pillars in the areas where the weak immediate floor has thinned vertically. This over-design leaves coal in situ which could have otherwise been extracted. This paper presents a plane strain numerical model to illustrate the effect of a change in bedding thickness of a weak immediate floor across one or two coal pillars. The floor bearing capacity of the variable floor below each pillar where then compared to the consistent floor. The results show that the varying bedding thickness of weak underclay has an impact on the bearing capacity of the floor. Geometrically with the decrease in bedding thickness for constant pillar width, the B/H ratio increases exponentially. The influence of varying bedding thickness on the floor bearing capacity is apparent at higher B/H ratios. The floor bearing capacity under a single pillar is in variable floor model if the average thickness remains constant. For single pillar, the average of the bedding thickness can be considered and for pillars in a panel, and a safety factor has been proposed to take into account this change in bedding thickness.

关键词： Bedding thickness klnderclay Fireclay Illinois Basin Floor bearing capacity Floor safety factor

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A Girls' Trip

Frontiers of Literary Studies in China-Selected Publications from Chinese Universities 2019年第2期13卷 262-297页

作者： WANG Anyi todd Foley(Translated) 不详 Departments of East Asian Studies and Comparative Literature New York University New York NY 10003 USA

When Fentian and Shui first set out, no one in the village thought it was a good idea. These two girls were too wild, prone to bold actions without really thin king them through, and if they weren't careful, they'd be... 详细信息

关键词： Cirlsf Trip Fentian set out