检索结果-南通市图书馆

Estimating the size and travel distance of Klapperhorn Mountain debris flows for risk analysis along railway, canada

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2008年第3期23卷 275-282页

作者： c. derek MARTIN Dept. civil and Environmental Engineering University of Alberta Edmonton Alberta Canada T6G 2W2Drs.

Debris flows occurring on Klapperhorn Mountain in the Yellowhead Pass in the canadian Rocky Mountains pose a significant hazard to railway operations at the base of the mountain. The size (volume) and travel distance of these debris flows play an important role in assessing the risk to the railway. GIS analysis, airphoto interpretation together with field work were undertaken on two debris flows located at track mileage 54.0 and 54.3. characteristics of these two debris flow events were analyzed, including debris flow path morphology and event behavior. Their sizes and travel distances were estimated using an empirical-statistical model (UBcDFLOW) under different initiation conditions. Their potential impact on the railway bridge was evaluated using a bridge blockage ratio.

关键词： Debris flow Size Travel distance Railway

Factor of safety of strain-softening slopes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 473-483页

作者： Hossein Rafiei Renani c.derek Martin Klohn crippen Berger Ltd. VancouverCanada Department of civil and Environmental Engineering University of AlbertaEdmontonCanada

Stability analysis of strain-softening slopes is carried out using the shear strength reduction method and Mohr-coulomb model with degrading cohesion and friction *** e ffect of strain-softening behavior on the slope factor of safety is investigated by performing a series of analyses for various slope geometries and strength *** charts and equations are developed to estimate the factor of safety of strain-softe ning slopes from the results of traditional stability analysis based on perfectly-plastic *** example applications including an open pit mine in weak rock and clay shale slope with daylighting bedding planes are *** results of limit equilibrium analysis and shear strength reduction method with perfectly-plastic models were in close *** perfectly-plastic models with peak strength properties led to overly optimistic results while adopting residual strength properties gave excessively conservative *** shear strength reduction method with a strain-softening model gave realistic factors of safety while accounting for the process of strength degradation.

关键词： Slope stability analysis Factor of safety ratio Shear strength reduction Perfectly-plastic behavior Open pit slope clay shale slope

Bank erosion in an Andean páramo river system: Implications for hydro-development and carbon dynamics in the neotropical Andes

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第2期16卷 243-255页

作者： derek J.MARTIN christopher ELY Beverley c.WEMPLE Department of Geography and Planning Appalachian State University Department of Geography University of Vermont

The páramo of the Northern Andes provide critically important ecosystem services to the Northern Andean region in the form of water provisioning and carbon sequestration, both of which are a result of the páramo?s organic-rich soils. Little is known, however, about the hydro-geomorphic characteristics of the rivers that drain these ecosystems. With impending plans for widespread hydro-development and increasing implementation of carbon-sequestering compensation for ecosystem services programs in the region it is imperative that we develop a thorough understanding of the hydrogeomorphic role that rivers play in this unique ecosystem. The objective of this study was to quantify bank erosion along an Amazonian headwater stream draining a small, relatively undisturbed páramo catchment to gain a better understanding of the natural erosion regime and the resulting sediment contributions from this unique ecosystem. This study implemented a combination of field, laboratory, and Geographic Information Systems techniques to quantify bank erosion rates and determine a bank erosion sediment yield from the Ningar River, a small páramo catchment(22.7 km^2) located in the eastern Andean cordillera of Ecuador. Results show that bank erosion rates range from 3.0 to ≥ 390.0 mm/yr, are highly episodic, and yield at least 487 tons of sediment annually to the Ningar River. These results imply that 1) páramo ecosystems substantially contribute to the sediment load of the Amazon River basin; 2) bank erosion is a potentially significant flux component of basin-scale carbon cycles in páramo ecosystems; and 3) hydrologic alteration campaigns(dam building) will likely critically alter these contributions and concomitantly disconnect a critical source of sediment and nutrients to downstream ecosystems.

关键词： Bank erosion Páramo Fluvial geomorphology Andes

Measuring powder flowability with a modified Warren Spring cohesion tester

在线全文

学校读者我要写书评

暂无评论

Particuology 2011年第2期9卷 148-154页

作者： Salam A.Mohammed Ezzat c.Abdullah derek Geldart Abdul Aziz A.Raman Department of chemical Engineering Faculty of EngineeringUniversity of Malaya Powder Research Ltd. Harrogate& University of Leeds

The measurement of powder flowability is a major concern for most industrial processes that deal with the handling of bulk solids as raw materials, intermediates, or products. The development of devices that measure the flowability of non-aerated powders has not progressed as rapidly as might have been hoped since most research activities have been based on various types of shear testers intended to aid the design of hoppers. A new flowability indicator named as weighted cohesion （WS） is established using newly improved version of direct cohesion texture. A cornerstone of the proposed technique is that the procedure is automated, using a digital Warren Spring tester called Warren Spring-University of Malaya cohesion tester （WSUMcT）, thus making results operator-insensitive. Besides being a practical tool to diagnose the cohesion of experimental powders, the ratio between measured cohesion （using WSUMcT） and aerated density （using Hosokawa PT-S） provides us with a powerful technique to research fundamental particle internal cohesion forces directly and use these data to indicate the flowability. In this work, a series of fine （9.4μm） and coarse （60 μm） porous silica gel particle mixtures, and mixtures of fine （28μm） and coarse （72 μm） glass ballotini as well, were used as test powders. The results from these tests agree well with relative flowability determined on our newly driven indicator using WSUMcT. The validation of aerated weighted cohesion （WSA） as a flowability indicator was authenticated by comparing the conducted parameter with established measured Hausner ratio （HR） and angle of repose （AoR）.

关键词： Flowability cohesion strength Hausner ratio Particle sizeAngle of reposecohesive powder

Dry powder platform for pulmonary drug delivery

在线全文

学校读者我要写书评

暂无评论

Particuology 2008年第4期6卷 225-238页

作者： derek Ivan Daniher Jesse Zhu Graduate Program in Biomedical Engineering Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonOntarioCanada

The phenomenon of particle interaction involved in pulmonary drug delivery belongs to a wide variety of disciplines of particle technology, in particular, fluidization. This paper reviews the basic concepts of pulmonary drug delivery with references to fluidization research, in particular, studies on Geldart group c powders. Dry powder inhaler device-formulation combination has been shown to be an effective method for delivering drugs to the lung for treatment of asthma, chronic obstructive pulmonary disease and cystic fibrosis. Even with advanced designs, however, delivery efficiency is still poor mainly due to powder dispersion problems which cause poor lung deposition and high dose variability. Drug particles used in current inhalers must be 1–5 μm in diameter for effective deposition in small-diameter airways and alveoli. These powders are very cohesive, have poor flowability, and are difficult to disperse into aerosol due to cohesion arising from van der Waals attraction. These problems are well known in fluidization research, much of which is highly relevant to pulmonary drug delivery.

关键词： Dry powder inhaler Interparticle forces Aerosol Pulmonary drug delivery carrier particle Fluidization

Injectable mechanical pillows for attenuation of load-induced post-traumatic osteoarthritis

在线全文

学校读者我要写书评

暂无评论

Regenerative Biomaterials 2019年第4期6卷 211-219页

作者： derek T.Holyoak Tibra A.Wheeler Marjolein c.H.van der Meulen Ankur Singh Meinig School of Biomedical Engineering Cornell UniversityIthacaNY 14853USA Sibley School of Mechanical and Aerospace Engineering Cornell UniversityIthacaNY 14853USA Research Division Hospital for Special SurgeryNew YorkNY 10021USA Englander Institute for Precision Medicine Weill Cornell Medical CollegeCornell UniversityNew YorkNY 10021USA

Osteoarthritis(OA)of the knee joint is a degenerative disease initiated by mechanical stress that affects millions of *** disease manifests as joint damage and synovial ***-traumatic osteoarthritis(PTOA)is a specific form of OA caused by mechanical trauma to the *** progression of PTOA is prevented by immediate post-injury therapeutic ***-articular injection of anti-inflammatory therapeutics(***)is a common treatment option for OA before end-stage surgical ***,the efficacy of intra-articular injection is limited due to poor drug retention time in the joint space and the variable efficacy of ***,we endeavored to characterize a four-arm maleimide-functionalized polyethylene glycol(PEG-4MAL)hydrogel system as a‘mechanical pillow’to cushion the load-bearing joint,withstand repetitive loading and improve the efficacy of intra-articular injections of nanoparticles containing dexamethasone,an anti-inflammatory ***-4MAL hydrogels maintained their mechanical properties after physiologically relevant cyclic compression and released therapeutic payload in an on-demand manner under in vitro inflammatory ***,the on-demand hydrogels did not release nanoparticles under repetitive mechanical loading as experienced by daily *** dexamethasone had minimal protective effects on OA-like pathology in our studies,the PEG-4MAL hydrogel functioned as a mechanical pillow to protect the knee joint from cartilage degradation and inhibit osteophyte formation in an in vivo load-induced OA mouse model.

关键词： hydrogel osteophyte biomaterials drug delivery cartilage inflammation

Innovative approaches towards an economic fusion reactor

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

National Science Review 2020年第2期7卷 245-247页

作者： Houyang Guo Francis Y c Thio Michl W Binderbauer Richard J Buttery Thomas R Jarboe Rajesh Maingi John S Sarff Peter c Stangeby derek A SutherlAND Mickey R Wade Michael c Zarnstorff General Atomics Breakthrough Fusion International corporation

Nuclear fusion potentially offers a clean,environmentally friendly and intrinsically safe energy source with an abundant fuel supply. Magnetic fusion energy research is approaching a new era of fusion power reactor design and construction planning. New physics understanding and powerful predictive tools have become available for improving fusion performance, developing and optimizing various magnetic confinement concepts. Emerging transformative

关键词： Innovative approaches towards an economic fusion reactor

Exploring the impact of cOVID-19 on the movement behaviors of children and youth:A scoping review of evidence after the first year

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2021年第6期10卷 675-689页

作者： derek c.Paterson Katelynn Ramage Sarah A.Moore Negin Riazi Mark S.Tremblay Guy Faulkner School of Kinesiology Faculty of EducationUniversity of British ColumbiaVancouverBritish Columbia V6T 1Z4Canada School of Health and Human Performance Dalhousie UniversityHalifaxNova Scotia B3H 4R2Canada children’s Hospital of Eastern Ontario Research Institute OttawaOntario K1H 5B2Canada Department of Pediatrics University of OttawaOttawaOntario K1N 6N5Canada

Purpose:The objective of this scoping review was to summarize systematically the available literature investigating the relationships between the coronavirus disease 2019(cOVID-19)pandemic and movement behaviors(physical activity,sedentary behavior,and sleep)of school-aged children(aged 511 years)and youth(aged 1217 years)in the first year of the cOVID-19 ***:Searches for published literature were conducted across 6 databases on 2 separate search dates(November 25,2020,and January 27,2021).Results were screened and extracted by 2 reviewers(DcP and KR)independently,using *** numeric analysis and content analysis were undertaken to present thematically the findings of included studies according to the associated impact on each movement ***:A total of 1486 records were extracted from database searches;of those,150 met inclusion criteria and were included for *** 150 articles,110 were empirical studies examining physical activity(n=77),sedentary behavior/screen time(n=58),and sleep(n=55).Results consistently reported declines in physical-activity time,increases in screen time and total sedentary behavior,shifts to later bed and wake times,and increases in sleep *** reported impacts on movement behaviors were greater for youth than for ***:The cOVID-19 pandemic is related to changes in the quantity and nature of physical activity,sedentary behavior,and sleep among children and *** is an urgent need for policy makers,practitioners,and researchers to develop solutions for attenuating adverse changes in physical activity and screen time among children and youth.

关键词： Pandemic Physical activity Screen time Sedentary Sleep

Effect of opioid dependence or abuse on opioid utilization after shoulder arthroplasty

在线全文

学校读者我要写书评

暂无评论

World Journal of Orthopedics 2018年第8期9卷 105-111页

作者： derek D Berglund Samuel Rosas Jennifer Kurowicki Dragomir Mijic Jonathan c Levy Department of Orthopedic Surgery Holy Cross Orthopedic Institute Department of Orthopedic Surgery Wake Forest School of Medicine Department of Orthopaedic Surgery Seton Hall University School of Health and Medical Sciences

AIM To examine whether opioid dependence or abuse has an effect on opioid utilization after anatomic or reverse total shoulder arthroplasty(TSA).METHODS All anatomic TSA(IcD-9 81.80) and reverse shoulder arthroplasty(RSA)(IcD-9 81.88) procedures from 2007 to 2015 were queried from within the Humana claims database utilizing the Pearl Diver supercomputer(colorado Springs, cO). Study groups were formed based on the presence or absence of a previous history of opioid dependence(IcD-9 304.00 and 304.03) or abuse(IcD-9 305.50 and 305.53). Opioid utilization among the groups was tracked monthly up to 1 year post-operatively utilizing National Drug codes. A secondary analysis was performed to determine risk factors for pre-operative opioid dependence or *** Two percent of TSA(157 out of 7838) and 3% of RSA(206 out of 6920) patients had a history of opioid dependence or abuse. For both TSA and RSA, opioid utilization was significantly higher in opioid dependent patients at all post-operative intervals(P cidence of opioid use among groups was similar within the first post-operative month. After TSA, opioid dependent patients were over twice as likely to fill opioid prescriptions during the post-operative months 1-12. Following RSA, opioid dependent patients were over 3 times as likely to utilize opioids from months 3-12. Age less than 65 years, history of mood disorder, and history of chronic pain were significant risk factors for pre-operative opioid dependence/abuse in patients who underwent TSA or *** Following shoulder arthroplasty, opioid use between opioid-dependent and non-dependent patients is similar within the first post-operative month but is greater among opioid-dependent patients from months 2-12.

关键词： Opioid Narcotic Abuse Dependence Anatomic total shoulder arthroplasty Reverse shoulder arthroplasty chronic pain Mood disorder