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Human activities are intensifying the spatial variation of landslides in the Yellow River Basin

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Science Bulletin 2025年第2期70卷 263-272页

作者： Naiman Tian Hengxing Lan Langping Li Jianbing Peng Bojie Fu John J.Clague State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China university of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Ecological Geology and Disaster Prevention Ministry of Natural ResourcesXi’an 710054China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Department of Earth Sciences Simon Fraser UniversityBurnaby BCV5A 1S6Canada

Human activities are a triggering factor for landslides in the Yellow River Basin(YRB,China).However,the extent to which the spatial distribution of landslides is affected by human activities is *** constructed a human activity intensity index(HAII)based on nighttime light data and land cover *** and dominance analyses were used to compare the effects of the HAII,precipitation,distance to river,distance to fault,topographic relief and slope on the landslides spatial density(LSD).The results showed that in the YRB,the HAII,as a dominance influencing factor,had a significant positive influence on the ***,regional differences in the human disturbance of nature intensify the spatial variation of *** quantify the intensity of human disturbance to nature,a human-nature conflict index(HNCI)is constructed by quantifying the difference between the slope distributions of artificial and natural *** results show that in the middle section of the YRB,humans are developing more steep mountainous areas,leading to more dense *** study provides a reference for landslide risk management and land use planning in the YRB.

关键词： Landslide Human activities Spatial variation Human-nature conflict Yellow River Basin

CONVERGENCE RATES FOR DIFFERENCE SCHEMES FOR POLYHEDRAL NONLINEAR PARABOLIC EQUATIONS

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Journal of Computational Mathematics 2010年第4期28卷 474-488页

作者： Adam M.Oberman Department of Mathematics Simon Fraser University

We build finite difference schemes for a class of fully nonlinear parabolic equations. The schemes are polyhedral and grid aligned. While this is a restrictive class of schemes, a wide class of equations are well approximated by equations from this class. For regular （C2,α） solutions of uniformly parabolic equations, we also establish of convergence rate of O（α）. A case study along with supporting numerical results is included.

关键词： Error estimates Convergence rate Viscosity solutions Finite difference schemes

Effect of Orientation of Fibers and Holes on the Radial Strain Amplification of Campaniform sensilla

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Journal of Bionic Engineering 2010年第4期7卷 314-320页

作者： Nickolas L.M.Mani Carlo Menon MENRVA Research Group School of Engineering ScienceSimon Fraser University MENRVA Research Group School of Engineering Science Simon Fraser University

In this paper,a structural analysis is performed to gain insights on the synergistic mechanical amplification effect thatCampaniform sensilla have when combined in an array *** order to simplify the analysis performed in this preliminaryinvestigation,an array of four holes in a single orthotropic lamina is ***,a Finite Element Method(FEM) analysis is performed to discretely assess the influence that different geometrical parameters have on the mechanicalamplification properties of the ***,an artificial neural network is used to obtain an approximated multi-dimensionalcontinuous function,which models the relationship between the geometrical parameters and the amplification properties of ***,an optimization is performed to identify the geometrical parameters yielding the maximum mechanical ***,results are validated with an additional FEM simulation performed by varying geometrical parameters in theneighborhood of the identified optimal *** method proposed in this paper can be fully automated and used to solvea wide range of optimization problems aimed at identifying optimal configurations of strain sensors inspired by Campaniformsensilla.

关键词： Campaniform sensillum strain sensor FEM ANN optimization

ANALYSIS OF FREEMIUM BUSINESS MODEL CONSIDERING NETWORK EXTERNALITIES AND CONSUMER UNCERTAINTY

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Journal of Systems Science and Systems Engineering 2018年第1期27卷 78-105页

作者： Wuhua Chen Zhongsheng Hua Zhe George Zhang Wenjie Bi Beedie School of Business simon fraser university Burnaby Canada

An emerging business model increasingly used by companies in the online software market is to provide both a free basic version and a paid premium version for a service or a product to customers. Such a setting is often called freemium model. The existence of the free version can reduce the customer uncertainty regarding the evaluation of the commercial software and make use of network effect to improve the firm＇s profit. However, the freemium model may also have the cannibalization effect which can hurt the profit. Hence, the from needs to determine the optimal content for the free version and the optimal price for the premium version to maximize its profit. In this paper, thst, we obtain the optimal decisions of the freemium model and their properties. Second, we compare the freemium model with the traditional charge-for-everything model that all content of the product need to be charged in terms of the profit, customer welfare, and social welfare. The results show that when customer underestimates the value of the software significantly and the true value of the software is high enough, the freemium model can generate higher profit, higher customer welfare, and higher social welfare. Otherwise, the freemium model may not deliver the desired results.

关键词： Freemium pricing network effect customer uncertainty software social welfare

Mixed reality emergency management:bringing virtual evacuation simulations into real-world built environments

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International Journal of Digital Earth 2019年第2期12卷 190-208页

作者： Ian Lochhead Nick Hedley Department of Geography Simon Fraser UniversityBurnabyCanada

Computer-based evacuation simulations are important tools for emergency *** simulations vary in complexity and include 2D and 3D GIS-based network analyses,agent-based models,and sophisticated models built on documented human behaviour and particle *** the influential role of built environments in determining human movement,a disconnect often exists between the features of the real world and the way they are represented within these simulation *** proliferation of emergency management location-aware mobile devices,along with a recent infatuation for augmented reality(AR),has resulted in new wayfinding and hazard assessment tools that bridge this gap,allowing users to visualize geospatial information superimposed on the real *** this paper,we report research and development that has produced AR geovisual analytical systems,enabling visual analysis of human dynamics in multilevel built environments with complex thoroughfare network *** demonstrate prototypes that show how mixed reality visual analysis of intelligent human movement simulations built in virtual spaces can become part of real *** research introduces a fundamentally new way to view and link simulations of people with the real-world context of the built environment:mixed reality crowd simulation in real space.

关键词： Augmented reality 3D geovisualization situated simulation human movement analysis emergency management

Discernible image mosaic with edge-aware adaptive tiles

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Computational Visual Media 2019年第1期5卷 45-58页

作者： Pengfei Xu Jianqiang Ding Hao Zhang Hui Huang College of Computer Science and Software Engineering Shenzhen University School of Computing Science Simon Fraser University

We present a novel method to produce discernible image mosaics, with relatively large image tiles replaced by images drawn from a database, to resemble a target image. Compared to existing works on image mosaics, the novelty of our method is ***, believing that the presence of visual edges in the final image mosaic strongly supports image perception,we develop an edge-aware photo retrieval scheme which emphasizes the preservation of visual edges in the target image. Secondly, unlike most previous works which apply a pre-determined partition to an input image, our image mosaics are composed of adaptive tiles, whose sizes are determined based on the available images in the database and the objective of maximizing resemblance to the target image. We show discernible image mosaics obtained by our method, using image collections of only moderate size. To evaluate our method, we conducted a user study to validate that the image mosaics generated present both globally and locally appropriate visual impressions to the human observers. Visual comparisons with existing techniques demonstrate the superiority of our method in terms of mosaic quality and perceptibility.

关键词： image mosaic image retrieval image synthesis

Development of a spring analogue approach for the study of pillars and shafts

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International Journal of Mining Science and Technology 2018年第2期28卷 267-274页

作者： Amichai Mitelman Davide Elmo Doug Stead NBK Institute of Mining Engineering University of British Columbia Department of Earth Sciences Simon Fraser University

In civil and mining operations that involve ground excavation and support, the loads are distributed between the ground and support depending on their relative stiffness. This paper presents the development of conceptual single-degree-of-freedom models, which are used to derive equations for estimating displacements and stresses for ground-support interaction problems encountered in pillars in room-andpillar mining(natural support system), and liners for circular vertical shafts(artificial support systems).For pillar assessment, mine-pillar interaction curves can be constructed using a double spring ***, the effectiveness of different support systems can be evaluated depending on their effect upon the mine-pillar system. For shaft design, an initial estimation of the required lining strength and thickness can be readily made based on a double ring analogue. For both problems, the results from the proposed approach compare well with those obtained by finite element numerical simulations.

关键词： Room and pillar Shafts Ground-support interaction Spring analogue Rockbolts

Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins

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Geoscience Frontiers 2018年第4期9卷 967-975页

作者： Gautier Nicoli Brendan Dyck Department of Earth Sciences University of Cambridge Department of Earth Sciences Simon Fraser University

Shale and greywacke compositions from the Archean to Phanerozoic record a secular change in the siliciclastic material that comprises much of Earth＇s continental margins, past and present. This study explores the metamorphic consequence of these compositional changes, by comparing phase equilibrium models constructed for average Archean, Proterozoic, and Phanerozoic shale and greywacke compositions equilibrated along two Barrovian-type geotherms： 1330℃/GPa（A） and 800 ℃/GPa（B）. Our models show that Archean siliciclastic rocks can retain up to 4 vol.% water at middle to lower crustal conditions, nearly twice that of Proterozoic and Phanerozoic compositions. The increased ferromagnesium content of Archean siliciclastic rocks stabilizes chlorite to higher temperatures and results in a biotite-rich assemblage at solidus temperatures. Accordingly, water-absent biotite dehydration melting is predicted to play a greater role in the generation of melt in the metamorphism of Archean aged units,and water-absent muscovite dehydration melting is of increasing importance through the Proterozoic and Phanerozoic. This secular variation in predicted mineral assemblages demonstrates the care with which metamorphic facies diagrams should be applied to Archean compositions. Moreover, secular changes in the composition of shale and greywacke is reflected in the evolution of anatectic melt towards an increasingly less viscous, Ca-rich, and Mg-poor monzogranite.

关键词： Secular change Shale Greywacke Dehydration melting Thermodynamic modelling Perple_X

Enhanced Compliant Adhesive Design and Fabrication with Dual-Level Hierarchical Structure

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Journal of Bionic Engineering 2010年第3期7卷 228-234页

作者： Dan Sameoto Carlo Menon Department of Mechanical Engineering University of Alberta MENRVA Lab School of Engineering ScienceSimon Fraser University

Synthetic dry adhesives inspired by the nano-and micro-scale hairs found on the feet of geckos and some spiders have beendeveloped for almost a decade. Elastomeric single level micro-scale mushroom shaped fibres are currently able to function evenbetter than natural dry adhesives on smooth surfaces under normal loading. However, the adhesion of these single level syntheticdry adhesives on rough surfaces is still not optimal because of the reduced contact surface area. In nature, contact area ismaximized by hierarchically structuring different scales of fibres capable of conforming surface roughness. In this paper, weadapt the nature’s solution arid propose a novel dual-level hierarchical adhesive design using Polydimethylsiloxane (PDMS),which is tested under peel loading at different orientations. A negative macro-scale mold is manufactured by using a laser cutterto define holes in a Poly(methyl methacrylate) (PMMA) plate. After casting PDMS macro-scale fibres by using the obtainedPMMA mold, a previously prepared micro-fibre adhesive is bonded to the macro-scale fibre substrate. Once the bondingpolymer is cured, the micro-fibre adhesive is cut to form macro scale mushroom caps. Each macro-fibre of the resulting hierarchicaladhesive is able to conform to loads applied in different directions. The dual-level structure enhances the peel strengthon smooth surfaces compared to a single-level dry adhesive, but also weakens the shear strength of the adhesive for a given areain contact. The adhesive appears to be very performance sensitive to the specific size of the fibre tips, and experiments indicatethat designing hierarchical structures is not as simple as placing multiple scales of fibres on top of one another, but can requiresignificant design optimization to enhance the contact mechanics and adhesion strength.

关键词： biomimetics dry adhesive hierarchical dual-level adhesive silicone polymer