检索结果-南通市图书馆

Nanoscale mechanical property variations concerning mineral composition and contact of marine shale

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2022年第4期13卷 165-180页

作者： Yong Li Jianqi Chen derek Elsworth Zhejun Pan Xiaotian Ma State Key Laboratory of Coal Resources and Safe Mining College of Geosciences and Surveying EngineeringChina University of Mining and TechnologyBeijing 100083China Department of Energy and Mineral Engineering GeosciencesEMS Energy Institute and the G3 CenterPennsylvania State UniversityUniversity ParkPA 16802USA Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development Ministry of EducationNortheast Petroleum UniversityDaqingHeilongjiang 163318China

Mechanical properties of shales are key parameters influencing hydrocarbon production – impacting borehole stability, hydraulic fracture extension and microscale variations in in situ stress. We use Ordovician shale(Sichuan Basin, China) as a type-example to characterize variations in mineral particle properties at microscale including particle morphology, form of contact and spatial distribution via mineral liberation analysis(MLA) and scanning electron microscopy(SEM). Deformation-based constitutive models are then built using finite element methods to define the impact of various architectures of fracture and mineral distributions at nanometer scale on the deformation characteristics at *** compositions of siliceous, calcareous and clay mineral particles are shown to be the key factors influencing brittleness. Shales with similar mineral composition show a spectrum of equivalent medium mechanical properties due to differing particle morphology and mineral heterogeneity. The predominance of small particles and/or point-point contacts are conducive to brittle failure, in general, and especially so when quartz-rich. Fracture morphology, length and extent of filling all influence shale deformability. High aspect-ratio fractures concentrate stress at fracture tips and are conducive to extension, as when part-filled by carbonate minerals. As fracture spacing increases, stress transfer between adjacent fractures weakens, stress concentrations are amplified and fracture extension is favored. The higher the fractal dimension of the fracture and heterogeneity of the host the more pervasive the fractures. Moreover, when fractures extend, their potential for intersection and interconnection contributes to a reduction in strength and the promotion of brittle failure. Thus, these results provide important theoretical insights into the role of heterogeneity on the deformability and strength of shale reservoirs with practical implications for their stimulation an

关键词： Shale oil and gas Shale lithofacies Mineral composition Multiscale mechanical property Nanoscale mechanics Finite-element simulation

Environmental drivers of seasonal shifts in abundance of wild pigs(Sus scrofa)in a tropical island environment

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2022年第1期11卷 772-786页

作者： derek R.Risch Shaya Honarvar Melissa R.Price Natural Resources and Environmental Department University of Hawaiʻi at Mānoa1910 East-West RoadHonoluluHI 96822USA Pacific Cooperative Studies Unit University of Hawaiʻi at Mānoa3190 Maile WayHonoluluHI 96822USA

Background:Non-native wild pigs(Sus scrofa)threaten sensitive flora and fauna,cost billions of dollars in economic damage,and pose a significant human–wildlife conflict *** growing interest in wild pig research,basic life history information is often lacking throughout their introduced range and particularly in tropical *** to other large terrestrial mammals,pigs possess the ability to shift their range based on local climatic conditions or resource availability,further complicating management *** objectives of this study were to(i)model the distribution and abundance of wild pigs across two seasons within a single calendar year;(ii)determine the most important environmental variables driving changes in pig distribution and abundance;and(iii)highlight key differences between seasonal models and their potential management *** study objectives were achieved using zero-inflated models constructed from abundance data obtained from extensive field surveys and remotely sensed environmental ***:Our models demonstrate a considerable change in distribution and abundance of wild pigs throughout a single calendar *** and vegetation height were among the most influential variables for pig distribution during the spring,and distance to adjacent forest and vegetation density were among the most significant for the ***,our seasonal models show that areas of high conservation value may be more vulnerable to threats from wild pigs at certain times throughout the year,which was not captured by more traditional modeling approaches using aggregated ***:Our results suggest that(i)wild pigs can considerably shift their range throughout the calendar year,even in tropical environments;(ii)pigs prefer dense forested areas in the presence of either hunting pressure or an abundance of frugivorous plants,but may shift to adjacent areas in the absence of either of these conditions;and(iii)seasonal m

关键词： Ecology Spatial Temporal Species distribution modeling Wild boar Sus scrofa Feral pigs

Influences of spherical tree canopy on thermal radiation disturbance to exterior wall under the condition of no shade cast on the wall

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2022年第7期15卷 1367-1383页

作者： Tailong Zhang Xiaoyue Zhao Yu Zhao derek Lukolongo Mwewa Chabi Feng Qi School of Landscape Architecture Zhejiang A&F UniversityLin'an 371300China

Research on the influence of thermal radiation of tree canopies to adjacent exterior walls has relevance to the selection of tree species and the spatial arrangement of trees for urban *** the last decade,there have been many studies on the influence of tree shadows on the thermal environment and energy consumption of ***,there is a lack of research on how trees affect the thermal radiation of adjacent buildings,when they do not cast direct shadows on the *** view of this,a combination of experiment and simulation was used to explore the influence of spherical canopy on the intensity changes of net long-wave thermal radiation(T_(RDL))and net short-wave thermal radiation(T_(RDS))absorbed by the adjacent *** measured and simulated results show that the tree canopy has a T_(RD)(the sum of T_(RDL) and T_(RDS))effect on the south wall of adjacent buildings in *** peak of T_(RD) from the tree to the adjacent wall was obtained by ENVI-met under 27 scenarios.A functional relationship was further given between the peak T_(RD) and the canopy diameter(D_(C)),the minimum distance between wall and tree canopy(D_(W-T)).Moreover,the influence of D_(C),D_(W-T) and leaf area density(LAD)on T_(RD) was discussed by ***,the Trd of canopy decays exponentially in the horizontal direction and linearly in the vertical direction of the *** above methods and results can guide the selection of tree species,green space design around buildings and the evaluation of the influence of trees on indoor cooling energy consumption in summer.

关键词： tree canopy thermal radiation disturbance exterior wall ENVI-met

The effect of rosin acid on hydrodeoxygenation of fatty acid

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2019年第1期28卷 85-94页

作者： Houman Ojagh derek Creaser Muhammad Abdus Salam Eva Lind Grennfelt Louise Olsson Competence Centre for Catalysis Chemical Engineering Chalmers University of Technology Preem AB

In this study, inhibition of tall oil fatty acid hydrodeoxygenation(HDO) activity due to addition of rosin acid over sulfided Ni Mo/Al_2O_3 was investigated. Oleic acid and abietic acid were used as model compounds for fatty acid and rosin acid respectively in tall oil. After completion of each HDO experiment,the Ni Mo catalysts were recovered and used again under the same conditions. The results showed that the oleic acid HDO activity of sulfided catalysts was inhibited by addition of abietic acid due to competitive adsorption and increased coke deposition. The rate of carbon deposition on the catalysts increased when abietic acid was added to oleic acid feed. Moreover, the coke was in a more advanced form with higher stability for the catalysts exposed to both oleic acid and abietic acid. Furthermore, a clear correlation between the rate of coke formation and concentration of abietic acid was observed.

关键词： Rosin acid Carbon deposition Coke formation Hydrodeoxygenation(HDO) Inhibition

Coupled hydro-mechanical evolution of fracture permeability in sand injectite intrusions

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2020年第4期12卷 742-751页

作者： Quan Gan derek Elsworth Yixin Zhao Antonio Grippa Andrew Hurst School of Geosciences University of AberdeenAberdeenUK State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyBeijingChina Department of Energy and Mineral Engineering EMS Energy Institute and G3 CenterPennsylvania State UniversityUniversity ParkPAUSA

Sandstone“injectite”intrusions are generally developed by the fluidization of weakly cemented sandstones and their subsequent injection into fractured *** this work,a continuum coupled hydromechanical model TOUGH-FLAC3D is applied to simulate the discrete fracture network in large-scale sand injectite complexes.A sand production constitutive model is incorporated to consider the formation of sand through plastic deformation and its influence on evolution of fracture *** in the fluidized sand slurry drives the injection with sand dikes intruded upwards,typically into previously low permeability“tight”mudstone *** contrast in poroelastic properties of the underlying weak sandstone and overlying injectite receptor directly affects the evolution of fracture aperture both during and after *** drainage into the unconsolidated matrix may reduce the extent of fracture aperture growth,through the formation of shear *** results of this work have broad implications related to the emplacement of sandstone intrusions and subsequent hydrocarbon accumulation,maturation and then production.

关键词： Sandstone intrusions Fracture permeability Sand fluidization Hydro-mechanical coupling

Soluble Triggering Receptor Expressed on Myeloid Cells-1 and Inflammatory Markers in Colorectal Cancer Surgery： A Prospective Cohort Study

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2017年第22期130卷 2691-2696页

作者： Lovorka derek Drazen Servis Adriana Unic Department of Clinical Chemistry Sestre Milosrdnice University Hospital Center Zagreb 10000 Croatia Department of General and Abdominal Surgery St. Anna Hospital Sulzbach-Rosenberg 92237 Germany

Background： Major abdominal surgery, including colorectal cancer （CRC） surgery, leads to systemic inflammatory response syndrome that can be detected and monitored with inflammatory markers testing. The aims of the study were to evaluate the usefulness of soluble triggering receptor expressed on myeloid cells-l （sTREM-1 ）, interleukin-6 （IL-6）, procalcitonin （PCT）, and C-reactive protein （CRP） in following the inflammatory response in CRC surgery and postoperative period, as well as to determine if duration of the surgery and the time that the colon has been opened during the surgery （open colon time [OCT]） refect a larger surgical stress through inflammatory markers rise. Methods： The study included 20 patients who underwent CRC surgery and 19 healthy volunteers from June 2011 to September 2012. We determined inflammatory markers 1 day before surgery （T0）, 24 h （T1）, 48 h （T2）, and 7 days after the surgery （T3）. All statistical analyses were calculated using MedCalc Statistical Software version 14.8.1 （MedCalc Software bvba, Ostend, Belgium）. Results： Concentrations ofCRP, PCT, and I L-6 in all measurement times were statistically different and sTREM- 1 did not yield statistical significance. A weak positive correlation was/bund between l L-6 in T 1 and T2 with the duration of the surgery （T 1 ： r= 0.4060, P 〈 0.0001 ; T2：r =0.3430, P〈0.0001）andOCT（T1：r= 0.3640, P〈0.0001,T2：r=0.3430, P〈0.0001）.AweakpositivecorrelationbetweenCRP in T2 and OCT （r = 0.4210, P 〈 0.0001 ） was also found. The interconnectivity of tested parameters showed a weak positive correlation between CRP and IL-6 in T1 （r= 0.3680; P 〈 0.0001 ）, moderate positive correlation in T2 （r = 0.6770; P 〈 0.0001）, and a strong positive correlation in T3 （r = 0.8651; P 〈 0.0001）. Conclusions： CRP, IL-6, and PCT were shown to be reliable for postoperative monitoring. Simultaneous determination of CRP and IL-6 might not be useful as they follow similar kinetics, sTREM- 1 might not be useful in CRC postoperat

关键词： Acute-phase Proteins Colorectal Cancer Surgery Soluble Triggering Receptor Expressed on Myeloid Cells-1

Rapid decompression and desorption induced energetic failure in coal

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2015年第3期7卷 345-350页

作者： Shugang Wang derek Elsworth Jishan Liu Department of Energy and Mineral Engineering EMS Energy Institute and G~3 Center Pennsylvania State University School of Mechanical and Chemical Engineering University of Western Australia

In this study, laboratory experiments are conducted to investigate the rapid decompression and desorption induced energetic failure in coal using a shock tube apparatus. Coal specimens are recovered from Colorado at a depth of 610 m. The coal specimens are saturated with the strong sorbing gas CO2 for a certain period and then the rupture disc is suddenly broken on top of the shock tube to generate a shock wave propagating upwards and a rarefaction wave propagating downwards through the *** rapid decompression and desorption has the potential to cause energetic fragmentation in *** types of behaviors in coal after rapid decompression are found, i.e. degassing without fragmentation, horizontal fragmentation, and vertical fragmentation. We speculate that the characteristics of fracture network（e.g. aperture, spacing, orientation and stiffness） and gas desorption play a role in this dynamic event as coal can be considered as a dual porosity, dual permeability, dual stiffness sorbing medium. This study has important implications in understanding energetic failure process in underground coal mines such as coal gas outbursts.

关键词： Rapid decompression Gas desorption Energetic failure Gas outburst Coal

Structural analysis of rubble-pile asteroids applied to collisional evolution

在线全文

学校读者我要写书评

暂无评论

Astrodynamics 2017年第1期1卷 57-69页

作者： Yang Yu derek CRichardson Patrick Michel School of Aeronautic Science and Technology Beihang UniversityBeijing 100191China Department of Astronomy University of MarylandCollege Park MD 20740-2421USA Observatoire de la Cote d'Azur UMR 7293 Lagrange/CNRS06304 Nice Cedex 4France

Solar system small bodies come in a wide variety of shapes and sizes,which are achieved following very individual evolutional paths through billions of ***,some common mechanisms can still be found during these processes,e.g.,rubble-pile asteroids tend towards fluid equilibrium as they are reshaped by external *** paper focuses on the reshaping process of rubble-pile asteroids driven by meteorite impacts.A mesoscale cluster of solid spheres is employed as the principal model for a rubble-pile asteroid,for which little is actually known about their interior *** take this simple model as a rough guide to the qualitative aspects of the reshaping processes,and it can reveal,to some degree,the inner workings of rubble-pile *** our study,numerous possible equilibrium configurations are obtained via Monte Carlo simulation,and the structural stability of these configurations is determined via eigen analysis of the geometric *** eigen decomposition reveals a connection between the cluster’s reactions and the types of external *** simulations are performed to verify the analytical *** gravitational N-body code pkdgrav is used to mimic the responses of the cluster under intermittent non-dispersive *** statistically confirm that the stability index I S,the total gravitational potential P G,and the volume of inertia ellipsoid V E show consistent tendency of variation.A common regime is found in which the clusters tend towards crystallization under intermittent impacts,i.e.,only the configurations with high structural stability survive under the external *** results suggest the trivial non-disruptive impacts might play an important role in the rearrangement of the constituent blocks,which may strengthen these rubble piles and help to build a robust structure under impacts of similar *** final part of this study consists of systematic simulations over two parameters

关键词： asteroids interior structure geological processes N-body simulations gravitational aggregates meteorite impacts

Primary care physicians'knowledge,attitude and perception towards homosexuality in Singapore

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Global Health Journal 2021年第4期5卷 209-214页

作者： derek Lim Seng Bin Ang Kandang Kerbau Women’s and Children’s Hospital 100 Bukit Timah Road Singapore

Aims:This study aim to gain insights into attitudes,acceptance and knowledge levels among family physicians toward homosexual people,which are important as they may affect care among this at-risk ***:An anonymized self-administered questionnaire in English was posted with the assistance of the College of Family Physicians Singapore in February 2015 to its 1529 members with self-addressed,pre-stamped envelopes for *** questionnaire included demographic questions such as age group,gender,religion,ethnicity,marital status and place of *** and scales that measured attitude,acceptance,knowledge and perception of colleagues who are homosexual were also included in the ***:451 responses(29.5%)were obtained,of which 441 were valid(28.84%).About 52.8%of participants were found to have negative,8.9%neutral and 38.3%positive attitudes toward ***(75.6%)were accepting of homosexuals,with 9.3%neutral and 15.1%not *** levels were poor,with a mean score of 6.9 out of a maximum of 13.A strong correlation was found between the attitudes towards lesbians and gay men(ATLG)and acceptance of homosexuals scales(r=0.69,P<0.001),with moderate correlations between acceptance and knowledge(r=0.54,P<0.001)and ATLG and Knowledge(r=0.54,P<0.001).Conclusion:Despite majority of family physicians having negative attitudes towards homosexuality,most are able to accept *** better education in sexual orientation in the medical educational curriculum,the increase in knowledge will lead to better care for people with homosexuality.

关键词： Attitudes Acceptance Family physician Homosexuality Knowledge Stigma Sexual orientation Singapore