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Utilizing a novel fiber optic technology to capture the axial responses of fully grouted rock bolts

Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 222-235页

作者： nicholas Vlachopoulos Daniel cruz Bradley Forbes Department of civil Engineering Royal Military College of Canada Department of Geological Sciences and Geological Engineering Queen's UniversityKingston

Rock bolts are one of the primary support systems utilized in underground excavations within the civil and mining engineering industries. Rock bolts support the weakened rock mass adjacent to the opening of an excavation by fastening to the more stable, undisturbed formations further from the excavation. The overall response of such a support element has been determined under varying loading conditions in the laboratory and in situ experiments in the past four decades; however, due to the limitations with conventional monitoring methods of capturing strain, there still exists a gap in knowledge associated with an understanding of the geomechanical responses of rock bolts at the microscale. In this paper, we try to address this current gap in scientific knowledge by utilizing a newly developed distributed optical strain sensing(DOS) technology that provides an exceptional spatial resolution of 0.65 mm to capture the strain along the rock bolt. This DOS technology utilizes Rayleigh optical frequency domain reflectometry(ROFDR) which provides unprecedented insight into various mechanisms associated with axially loaded rebar specimens of different embedment lengths, grouting materials, borehole annulus conditions, and borehole diameters. The embedment length of the specimens was found to be the factor that significantly affected the loading of the rebar. The critical embedment length for the fully grouted rock bolts(FGRBs) was systematically determined to be430 mm. The results herein highlight the effects of the variation of these individual parameters on the geomechanical responses FGRBs.

关键词： Fiber optic technology Fully grouted rock bolts Load transfer Stress distribution

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Astrometric calibration and source characterisation of the latest generation neuromorphic event-based cameras for space imaging

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Astrodynamics 2023年第4期7卷 415-443页

作者： nicholas Owen Ralph Alexandre Marcireau Saeed Afshar nicholas Tothill Andre van Schaik Gregory cohen International centre for Neuromorphic Systems MARCS Institute for BrainBehaviour and DevelopmentWestern Sydney UniversityKingswood 2747NSWAustralia

As an emerging approach to space situational awareness and space imaging,the practical use of an event-based camera(EBc)in space imaging for precise source analysis is still in its *** nature of event-based space imaging and data collection needs to be further explored to develop more effective event-based space imaging systems and advance the capabilities of event-based tracking systems with improved target measurement ***,for event measurements to be meaningful,a framework must be investigated for EBc calibration to project events from pixel array coordinates in the image plane to coordinates in a target resident space object’s reference *** this paper,the traditional techniques of conventional astronomy are reconsidered to properly utilise the EBc for space imaging and space situational *** paper presents the techniques and systems used for calibrating an EBc for reliable and accurate measurement *** techniques are vital in building event-based space imaging systems capable of real-world space situational awareness *** calibrating sources detected using the EBc,the spatiotemporal characteristics of detected sources or“event sources”can be related to the photometric characteristics of the underlying astrophysical ***,these characteristics are analysed to establish a foundation for principled processing and observing techniques which appropriately exploit the capabilities of the EBc.

关键词： neuromorphic event-based camera(EBc) space imaging space situational awareness(SSA) astronomy

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Onset temperature of intrinsic pinning in a REBcO coated conductor from critical current anisotropy

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Superconductivity 2022年第4期4卷 1-6页

作者： nicholas M.Strickland Arya Ambadiyil Soman Martin W.Rupich Stuart c.Wimbush Robinson Research Institute Victoria University of WellingtonWellingtonNew Zealand American Superconductor corporation AyerMA 01432USA

The field‐angle dependence of the critical current in a REBa_(2)cu_(3)O_(7) coated conductor has been measured over a fine range of temperatures from 15 K to 80 *** particular sample is demonstrated to have a very low fraction of extrinsic planar defects by its near‐isotropic critical current at 77 *** a representative magnetic field of 3 T we are able to track the emergence of the ab‐plane peak usually associated with intrinsic pinning and quantify its evolution with temperature by fitting to a maximum‐entropy *** are also able to observe the evolution of dip and peak features in the angle dependence of the power‐law index n with decreasing temperature and show that a dip appearing at 65 K is supplanted by a sharper positive peak from 50 *** combination of critical current and power‐law index temperature dependences shows the onset of intrinsic pinning at 50 K.

关键词： Intrinsic pinning REBcO coated conductors Maximum entropy N value

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cOVID-19 in Brazil:Epidemiological update and perspectives

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Asian Pacific Journal of Tropical Medicine 2020年第5期13卷 193-196页

作者： Marli c cupertino Graziela A cupertino Andréia P Gomes nicholas AJ Mayers R Siqueira-Batista Medical School Faculdade Dinamica do Vale do PirangaPonte NovaMinas GeraisBrazil Laboratory of Epidemiological and computational Methods in Health Department of Medicine and NursingUniversidade Federal de VicosaVicosaMinas GeraisBrazil Department of Veterinary Medicine Universidade Federal de VicosaVicosaMinas GeraisBrazil

coronaviruses are RNA viruses (Family: coronaviridae) constituents of a significant number of viruses that provoke diseases in animals and human beings. There are four genera of these microorganisms: Alphacoronavirus, Betacoronavirus, Deltacoronavirus and Gammacoronavirus. From this group, the alpha- and beta-coronaviruses are designated as human coronavirus (HcoV) for their propensity to infect human beings[1].

关键词： diseases corona Brazil

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Neoadjuvant treatment of esophageal cancer

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World Journal of Gastroenterology 2010年第30期16卷 3793-3803页

作者： nicholas P campbell Victoria M Villaflor Section of Hematology/Oncology Department of MedicineThe University of Chicago Pritzker School of MedicineChicagoIL 60637United States

The management of esophageal cancer has been evolving over the past 30 years. In the United States, multimodality treatment combining chemotherapy and radiotherapy (RT) prior to surgical resection has come to be accepted by many as the standard of care, although debate about its overall effect on survival still exists, and rightfully so. Despite recent improvements in detection and treatment, the overall survival of patients with esophageal cancer remains lower than most solid tumors, which highlights why further advances are so desperately needed. The aim of this article is to provide a complete review of the history of esophageal cancer treatment with the addition of chemotherapy, RT, and more recently, targeted agents to the surgical management of resectable disease.

关键词： Esophageal cancer Multimodality therapy Neoadjuvant therapy chemotherapy Radiotherapy Targeted agents Disease management

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Effect of contact geometry on the friction of acrylamide hydrogels with different surface structures

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Friction 2022年第3期10卷 360-373页

作者： Wenrui LIU Rok SIMIČ Yuhong LIU nicholas DSPENcER State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Laboratory for Surface Science and Technology Department of MaterialsETH Zurich8093 ZurichSwitzerland

Polyacrylamide(PAAm)hydrogels with brush-covered or crosslinked surfaces were produced and their tribological behavior was studied over a wide range of sliding speeds for two different contact geometries:sphere-on-flat and *** of the contact geometry,the brushy hydrogel surfaces displayed up to an order of magnitude lower coefficients of frictionμ(cOF)compared to the crosslinked surfaces,even achieving superlubricity(μcoefficient of friction than a flat hydrogel pin at a similar contact pressure over the entire range of sliding ***,after normalizing the friction force by the contact area,the shear stress of hydrogels with either crosslinked or brushy surfaces was found to be similar for both contact geometries at low speeds,indicating that hydrogel friction is unaffected by the contact geometry at these *** high sliding speeds,the shear stress was found to be lower for a sphere-on-flat configuration compared to a flat-pin-on-flat *** can be attributed to the larger equivalent hydrodynamic thickness due to the convergent inlet zone ahead of the sphere-on-flat contact,which presumably enhances the water supply in the contact,promotes rehydration,and thus reduces the friction at high sliding speeds compared to that measured for the flat-pin-on-flat contact.

关键词： hydrogels contact geometry aqueous lubrication friction coefficient(cOF) superlubricity

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Shaping Taste: The Molecular Discovery of Rice Genes Improving Grain Size, Shape and Quality

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Journal of Genetics and Genomics 2015年第11期42卷 597-599页

作者： nicholas P.Harberd Department of Plant Sciences University of Oxford

Modern-day human life is absolutely dependent upon the food that we derive from our crop plants. We eat grains, fruits, roots, tubers and other structures, all of which are constructed via coordinated organ growth. Whilst plant organ identity is first established in apical meristems （vegetative and floral shoot meristems and root meristems）, and in other meristematic regions, the final size and shape of organs are defined by subsequent coordination of organ expansion in longitudinal and transverse axes.

关键词： QTLs Shaping Taste The Molecular Discovery of Rice Genes Improving Grain Size Shape and Quality gene

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Testing for temperature acclimation of plant carbon exchange:a comment on‘Global patterns of the responses of leaf-level photosynthesis and respiration in terrestrial plants to experimental warming’by liang et al.

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Journal of Plant Ecology 2015年第3期8卷 333-334页

作者： nicholas G.Smith Department of Biological Sciences Purdue University915 West State StreetWest LafayetteIN 47907USA

In a recent issue of Journal of Plant Ecology,Liang et al.(2013)use meta-analytical techniques to analyze the leaf carbon exchanges responses to experimental warming and,in part,observe that leaf dark respiration,but not photosynthesis,acclimates to the warming *** authors should be commended for putting together and analyzing such a large data *** of the results provide fine syntheses for understanding leaf carbon exchange responses to ***,the acclimation analyses are,in my opinion,flawed and are not appropriate for supporting their results.

关键词： exchange carbon supporting

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Excited electronic states and internal conversion in cyanocobalamin

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chinese chemical Letters 2015年第4期26卷 439-443页

作者： Theodore E.Wiley Brenden c.Arruda nicholas A.Miller Michael Lenard Roseanne J.Sension Department of chemistry University of Michigan

cyanocobalamin （cNcbl） is a paradigm system for the study of excited electronic states and biological cofactors including the B12 vitamers, The photophysics of cNcbl has been thoroughly investigated using both ultrafast spectroscopy and time dependent density functional theory （TD-DFT）. Here we review the spectroscopic and theoretical investigations of cNcbl with emphasis on the nature of S1, the lowest excited electronic state, and extend the spectroscopic measurements to include the ultraviolet region of the spectrum. Ultrafast transient absorption measurements in the visible αβ band region and in the mid- infrared led to assignment of the S1 state to a ligand-to-metal charge transfer （LMcT） with lengthened axial bonds and a ~3 kcal/mol harrier for internal conversion to the ground state. The present measurements encompassing the y band region of the spectrum provide further support for the assignment of the S1 state. The experiments are in good agreement with the results of TD-DFT calculations which confirm the expected lengthening of the axial bonds in S1 and account for the observed barrier for internal conversion back to the ground state,

关键词： cyanocobalaminExcited electronic statesUltrafast spectroscopyTime dependent density functional theoryLigand-to-metal charge transfer

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chebfun and numerical quadrature

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Science china Mathematics 2012年第9期55卷 1749-1760页

作者： HALE nicholas TREFETHEN Lloyd N Mathematical Institute University of OxfordOxford OX1 3LBUK

chebfun is a Matlab-based software system that overloads Matlab's discrete operations for vectors and matrices to analogous continuous operations for functions and *** begin by describing chebfun's fast capabilities for clenshaw-curtis and also Gauss-Legendre,-Jacobi,-Hermite,and-Laguerre quadrature,based on algorithms of Waldvogel and Glaser,Liu and *** we consider how such methods can be applied to quadrature problems including 2D integrals over rectangles,fractional derivatives and integrals,functions defined on unbounded intervals,and the fast computation of weights for barycentric interpolation.

关键词： chebfun clenshaw-curtis quadrature Gauss quadrature barycentric interpolation formula Riemann-Liouville integral fractional calculus

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