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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

Nanoscale electropolishing of high-purity nickel with an ionic liquid

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 649-656页

作者： Jon derek Loftis Tarek M.Abdel-Fattah Applied Research Center at Thomas Jefferson National Accelerator Facility and Department of Molecular Biology and Chemistry at Christopher Newport University Department of Physical Sciences Virginia Institute of Marine Science College of William and Mary Faculty of Sciences Alexandria University

High purity(>99.9% composition) nickel metal specimens were used in electropolishing treatments with an acid-free ionic liquid electrolyte prepared from quaternary ammonium salts as a green polishing solution. Voltammetry and chronoamperometry tests were conducted to determine the optimum conditions for electrochemical polishing. Atomic force microscopy(AFM) revealed nanoscale effectiveness of each polishing treatment. Atomic force microscopy provided an overall observation of the material interface between the treated and unpolished regions. Surface morphology comparisons summarized electrochemical polishing efficiency by providing root-mean-square roughness averages before and after electrochemical polishing to reveal a mirror finish six times smoother than the same nickel metal surface prior to electropolishing. This transition manifested in a marked change in root-mean-squared roughness from 112.58 nm to 18.64 nm and producing a smooth mirror finish. Finally, the mechanism of the ionic liquid during electropolishing revealed decomposition of choline in the form of a transient choline radical by acceptance of an electron from the nickel-working electrode to decompose to trimethylamine and ethanol.

关键词： electrochemical polishing ionic liquid Ni 2EG:1VB4

Design and Implementation of an Automatic Over/Undervoltage Protection System for Single-Phase Low Voltage Power Lines

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Journal of Power and Energy Engineering 2022年第8期10卷 12-25页

作者： derek Ajesam Asoh Lizette Nange Chia Laboratoire de Génie Electrique Mécatronique et Traitement du Signal ENSPY University of Yaounde I Yaounde Cameroon Department of Electrical/Electronic Engineering NAHPI University of Bamenda Bamenda Cameroon Higher Technical Teacher Training College (HTTTC) University of Bamenda Bamenda Cameroon Research Unit Condensed Matter Electronics and Signal Processing Department of Physics Faculty of Science University of Dschang Dschang Cameroon

Today, many industrial and domestic electronic appliances and equipment (devices) are exposed to power disturbances such as voltage variations of the AC mains supply which often lead to damage of the electronic devices. As these devices are quite sensitive to power disturbances, there is a need for a tripping system that can help avoid any damage to devices in use. The objective of this work is to build a system that monitors line voltage and protects appliances from unacceptable voltage variations. The system consists of a tripping mechanism that monitors the input voltage and trips according to the limits provided. An Arduino Uno microcontroller is used to determine the voltage level through a voltage divider circuit. The system’s novelty and innovation lie in its flexibility. It offers the user the ability to define different overvoltage and undervoltage threshold values depending on the specific appliances used in the household. In operation, the system displays the voltage state (overvoltage, normal voltage, overvoltage) and alerts the user by sending an SMS via a GSM modem. The system is valuable for industrial and domestic applications, especially in developing economies such as those of Sub-Saharan Africa, where overvoltage and undervoltage are acute problems.

关键词： Overvoltage Undervoltage Simulation Arduino Microcontroller Tripping Mechanism Sub-Saharan Africa

Low-Cost Automated PV Panel Dust Cleaning System for Rural Communities

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Smart Grid and Renewable Energy 2022年第8期13卷 173-199页

作者： derek Ajesam Asoh Noel Nkwa Awangum Laboratoire de Génie Electrique Mécatronique et Traitement du Signal ENSPY University of Yaounde I Yaounde Cameroon Department of Electrical/Electronic Engineering NAHPI University of Bamenda Bamenda Cameroon Higher Technical Teacher Training College (HTTTC) University of Bamenda Bamenda Cameroon

Dust accumulation on photovoltaic (PV) panels degrades PV panels’ performance;leading to decreased power output and consequently high cost per generated kilowatt. Research addressing the severity of dust accumulation on PV panels has been ongoing since the 1940s, but proposed solutions have tended to increase the cost of PV systems either from oversizing or from cleaning the system. The objective of this work, therefore, is to design and implement a low-cost affordable automated PV panel dust cleaning system for use in rural communities of Sub-Saharan Africa (SSA);where financial resources are limited and significantly strained in meeting livelihood activities. Complete design and implementation details of a prototype system are provided for easy replication and capitalization on PV systems for sustainable energy needs. The system detects dust based on the innovative use of light-dependent resistors. Testing and observation of the system in operational mode reveal satisfactory performance;measured parameters quantify a power output increase of 33.76% as a result of cleaning dust off the PV panel used in the study.

关键词： PV Panel Automated Dust Cleaning Arduino Microcontroller Light Dependent Resistor Dust Percentage Threshold Low-Income Rural Communities Sub-Sahara Africa

Factor of safety of strain-softening slopes

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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

Desulfovibrio vulgaris as a model microbe for the study of corrosion under sulfate-reducing conditions

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mLife 2022年第1期1卷 13-20页

作者： Toshiyuki Ueki derek R.Lovley Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationElectrobiomaterials InstituteNortheastern UniversityShenyangChina Department of Microbiology University of Massachusetts AmherstMAUSA.

Corrosion of iron-containing metals under sulfate-reducing conditions is an economically important *** strains now known as Desulfovibrio vulgaris served as the model microbes in many of the foundational studies that developed existing models for the corrosion of iron-containing metals under sulfate-reducing *** mechanisms for corrosion by *** include:(1)H2 consumption to accelerate the oxidation of Fe0 coupled to the reduction of protons to H2;(2)production of sulfide that combines with ferrous iron to form iron sulfide coatings that promote H2 production;(3)moribund cells release hydrogenases that catalyze Fe0 oxidation with the production of H2;(4)direct electron transfer from Fe0 to cells;and(5)flavins serving as an electron shuttle for electron transfer between Fe0 and *** demonstrated possibility of conducting transcriptomic and proteomic analysis of cells growing on metal surfaces suggests that similar studies on *** corrosion biofilms can aid in identifying proteins that play an important role in *** for making targeted gene deletions in *** are available for functional genetic *** approaches,coupled with instrumentation for the detection of low concentrations of H2,and proven techniques for evaluating putative electron shuttle function,are expected to make it possible to determine which of the proposed mechanisms for *** corrosion are most important.

关键词： corrosion Desulfovibrio electron shuttle extracellular electron transfer Fe0 oxidation hydrogenase hydrogen uptake sulfate reduction sulfide

Engineering Colloidal Metal-Semiconductor Nanorods Hybrid Nanostructures for Photocatalysis

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Chinese Journal of Chemistry 2023年第22期41卷 3050-3062页

作者： Jiayi Chen derek Hao Wei Chen Yazi Liu Zongyou Yin Hsien-Yi Hsu Bing-Jie Ni Aixiang Wang Simon W.Lewis Guohua Jia School of Molecular and LifeSciences Curtin UniversityBentleyPerth WA6102Australia Centre for Technology in Water and Wastewater School of Civil and Environmental EngineeringUniversity of Technology SydneyUltimo NSW2007Australia School of the Environment Nanjing Normal UniversityNanjingJiangsu 210046China Research School of Chemistry TheAustralian National UniversityACT2601Australia School of Energy and Environment&Departmentof Materials Science and Engineering City University of Hong KongKowloon TongHongKongChinaand Shenzhen Research Instituteof City University of Hong KongShenzhen518057China school of Chemistry and Chemical Engineering LinyiUniversityLinyhandong 276005China

Emerging engineering strategies of colloidal metal-semiconductor nanorod hybrid nanostructures spanning from type,size,dimension,and location of both metal nanoparticles and semiconductors,co-catalyst,band gap structure,surface ligand to hole scavenger are elaborated symmetrically to rationalize the design of this type of intriguing materials for efficient photocatalytic applications.

关键词： Hybrid nanostructure Metal-semiconductor nanorod Engineering strategy Photocatalysis Hydrogen production

Shear behavior of ultrafine magnetite tailings subjected to freeze-thaw cycles

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International Journal of Mining Science and Technology 2019年第4期29卷 609-616页

作者： Chong Wei derek B.Apel Yunhai Zhang School of Mining and Petroleum Engineering University of AlbertaEdmontonAlberta T6G 2R3Canada School of Resources and Safety Engineering Central South UniversityChangsha 410083China

To study the shear behavior of the ultrafine magnetite tailings subjected to freeze-thaw cycles,unconsolidated-undrained shear tests were conducted on ultrafine-grained tailings that were subjected to 1-11 cycles of freeze-thaw and defined as a type of clayey silt under confining pressures of 100,200,and 300 *** the number of freeze-thaw cycles,cooling temperature,initial dry density,and moisture content as the four main influencing factors of shear behavior of the tailings samples,the shear stress-strain curve,compression modulus,failure strength,cohesion,and internal friction angle were *** results show that the freeze-thaw cycle has an obvious weakening effect on the shear behavior of the tailings material,and the shear mechanical parameters are affected by a combination of confining pressure,freeze-thaw cycle condition,and initial physical-mechanical properties of the tailings *** the microstructural analysis of the tailings samples subjected to freeze-thaw cycles,it shows that the freeze-thaw cycle mainly affects the porosity,bound water,and arrangement of the tailings ***,the macroscopic changes in shear strength indexes emerge,and then the stability of the tailings dam will decrease.

关键词： Ultrafine magnetite tailings(UMT) Freeze-thaw cycle Shear behavior Triaxial shear test

Mantle plumes,triple junctions and transforms:A reinterpretation of Pacific Cretaceous-Tertiary LIPs and the Laramide connection

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Geoscience Frontiers 2020年第4期11卷 1133-1144页

作者： Michael Fletcher derek A.Wyman Sabin Zahirovic EarthByte Group School of GeosciencesUniversity of SydneySydneyNew South Wales2006Australia

The Shatsky and Hess Rises,the Mid-Pacific Mountains and the Line Islands large igneous provinces(LIPs) present different challenges to conventional plume *** the genesis of these LIPs is important not only for a more complete understanding of mantle plumes and plume-generated magmatism,but also for establishing the role of subducted LIP conjugates in the evolution of the Laramide orogeny and other circum-Pacific orogenic events,which are related to the development of large porphyry *** past difficulties in developing consistent geodynamic models for these LIPs,it is useful to consider whether viable alternative geodynamic scenarios may be provided by recent concepts such as melt channel networks and channel-associated lineaments,along with the "two mode"model of melt generation,where a deeply-sourced channel network is superimposed on the plume,evolving and adapting over millions of years.A plume may also interact with transform faults in close proximity to a mid ocean ridge,with the resultant bathymetric character strongly affected by the relative age difference of lithosphere across the *** results suggest that the new two-mode melt models resolve key persistent issues associated with the Shatsky Rise and other LIPs and provide evidence for the existence of a conduit system within plumes that feed deeply-sourced material to the plume head,with flow maintained over considerable *** conduit system eventually breaks down during plume-ridge separation and may do so prior to the plume head being freed from the triple junction or spreading *** is evidence for not only plume head capture by a triple junction but also for substantial deformation of the plume stem as the distance between the stem and anchored plume head *** evidence suggests that young transforms can serve as pathways for plume material migration,at least in certain plume head-transform configurations.A fortuitous similarity between the path of the

关键词： Mantle plume Shatsky rise Hess rise Mid-pacific mountains Laramide orogeny

Performance evaluation of near real-time condition monitoring in haul trucks

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International Journal of Mining Science and Technology 2020年第6期30卷 909-915页

作者： Hemanth Reddy Alla Robert Hall derek B.Apel University of Alberta Edmonton T6G 2H5Canada

Strategic maintenance plays a key role in ensuring high availability and utilization of the haul trucks,and as equipment began to grow more complex towards the end of the 20th century,there was a need for a proactive maintenance strategy,which led to the development of condition-based *** condition monitoring(RTCM)is the ability to perform condition monitoring in real-time and has the ability to alert maintenance and operations of abnormal *** alarms can be used as an indication leading to a problem,and if a suitable corrective action is initiated in time,it could result in significant savings of equipment downtime and repair *** study aims to compare some maintenance performance indicators prior to and after implementation of RTCM strategy at a mine site using some tests of statistical *** study also indicated the presence of seasonality in the data,and thus the data was deseasonalized and detrended prior to being subjected to the statistical ***,the results indicated that RTCM strategy has proven to be successful in improving the availability for some of the failure categories chosen in this study.

关键词： Haul trucks Real-time condition monitoring Performance indicators