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Science China(Technological Sciences) 2010年第7期53卷 2008-2014页

作者： Billie f spencer department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign

To ensure the anti-earthquake performances of super-long-span suspension bridges, effective devices should be employed to control the seismic response of key sections. In this paper, four kinds of assessment functions for seismic response control effect are formulated based on the mechanism of seismic response control with dampers and the seismic response characteristics of long-span suspension bridges. A new optimal placement method of dampers using penalty function and first-order optimization theory is then proposed. Runyang suspension bridge (RSB) with a main span of 1490 m is then taken as an example. After seismic response time-history analyses on RSB using different placements of dampers, the analysis results are optimized by employing the optimal placement method and the optimal placements of dampers with the four assessment functions are then achieved respectively. Comparison of the four optimal control effects show that different assessment functions can lead to different optimal placements when the number of dampers is certain, but all placements of dampers can reduce the seismic response of RSB significantly. The selection of assessment functions and damper optimal placement should be determined by the structural characteristics and by what is considered in the structures. Results also show that the first-order optimization is an effective method on determining the optimal placement of dampers.

关键词： suspension bridge seismic control damper placement control effect assessment first-order optimization method

An improved optimal elemental method for updating finite element models

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Earthquake Engineering and Engineering Vibration 2004年第1期3卷 67-74页

作者：段忠东 spencer B.f. 闫桂荣欧进萍 School of Civil Engineering Harbin Institute of Technology department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign

The optimal matrix method and optimal elemental method used to update finite element models may not provide accurate *** situation occurs when the test modal model is incomplete,as is often the case in *** improved optimal elemental method is presented that defines a new objective function,and as a byproduct,circumvents the need for mass normalized modal shapes,which are also not readily available in *** solve the group of nonlinear equations created by the improved optimal method,the Lagrange multiplier method and Matlab function fmincon are *** deal with actual complex structures, the float-encoding genetic algorithm(fGA)is introduced to enhance the capability of the improved *** examples,a 7- degree of freedom(dOf)mass-spring system and a 53-dOf planar frame,respectively,are updated using the improved method. The example results demonstrate the advantages of the improved method over existing optimal methods,and show that the genetic algorithm is an effective way to update the models used for actual complex structures.

关键词： model updating optimal elemental method Lagrangc multiplier method genetic algorithm

development of a building information model-guided post-earthquake building inspection framework using 3d synthetic environments

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Earthquake Engineering and Engineering Vibration 2023年第2期22卷 279-307页

作者： Nathaniel M.Levine Yasutaka Narazaki Billie f.spencer department of Civil and Environmental Engineering University of Illinois at Urbana-ChampaignUrbanaIllinois 61801USA Zhejiang University-University of Illinois at Urbana-Champaign Institute Zhejiang UniversityHaining 314400China

Computer vision-based inspection methods show promise for automating post-earthquake building *** methods survey a building with unmanned aerial vehicles and automatically detect damage in the collected ***,assessing the damage′s impact on structural safety requires localizing damage to specific building components with known design and *** paper proposes a BIM-based automated inspection framework to provide context for visual surveys.A deep learning-based semantic segmentation algorithm is trained to automatically identify damage in *** BIM automatically associates any identified damage with specific building ***,components are classified into damage states consistent with component fragility models for integration with a structural *** demonstrate the framework,methods are developed to photorealistically simulate severe structural damage in a synthetic computer graphics environment.A graphics model of a real building in Urbana,Illinois,is generated to test the framework;the model is integrated with a structural analysis to apply earthquake damage in a physically realistic manner.A simulated UAV survey is flown of the graphics model and the framework is *** method achieves high accuracy in assigning damage states to visible structural *** assignment enables integration with a performance-based earthquake assessment to classify building safety.

关键词： computer vision earthquake engineering building information model physics-based graphics model synthetic environment

Comparing the Structural Parameters of the Milky Way to Other Spiral Galaxies

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Research in Astronomy and Astrophysics 2024年第3期24卷 10-28页

作者： Jacob A.Guerrette Aleksandr V.Mosenkov dallin spencer Zacory d.Shakespear department of Physics and AstronomyN283 ESCBrigham Young University ProvoUT 84602USA

The structural parameters of a galaxy can be used to gain insight into its formation and evolution *** this paper,we strive to compare the Milky Way’s structural parameters to other,primarily edge-on,spiral galaxies in order to determine how our Galaxy measures up to the Local *** our comparison,we use the galaxy structural parameters gathered from a variety of literature sources in the optical and near-infrared wave *** compare the scale length,scale height,and disk flatness for both the thin and thick disks,the thick-to-thin disk mass ratio,the bulge-to-total luminosity ratio,and the mean pitch angle of the Milky Way’s spiral arms to those in other *** conclude that many of the Milky Way’s structural parameters are largely ordinary and typical of spiral galaxies in the Local Universe,though the Galaxy’s thick disk appears to be appreciably thinner and less extended than expected from zoom-in cosmological simulations of Milky Way-mass galaxies with a significant contribution of galaxy mergers involving satellite galaxies.

关键词： Galaxy disk-galaxies fundamental parameters-Galaxy structure

Pediatric upper extremity firearm injuries:an analysis of demographic factors and recurring mechanisms of injury

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World Journal of Pediatrics 2021年第5期17卷 527-535页

作者： d.spencer Nichols Mitsy Audate Caroline King david Kerekes Harvey Chim Ellen Satteson University of florida College of Medicine.Gainesville FL.USA department of Surgery Division of Plastic and Reconstructive Surgery.University of Florida College of Medicine100138GainesvilleFL 32610USA

Background Little is known regarding risk factors specific to pedialric upper extremity firearm *** purpose of this study is to evaluate pediatric patients treated for these injuries to identify at-risk populations and recurring mechanisms of *** A 20-year retrospective review was *** 17 years of age and younger,with upper extremity injuries related to a firearm,were *** involved fisher's exact and Chi-square *** One hundred and eighty patients were *** mean age was 12.04±4.3 *** included patients were male(85%).Interestingly,females were more frequently victims of assault(P=0.03),and males were more frequently injured due to accidental discharge(Pffected race/ethnicity was White-not Hispanic or Latino(48%).The hand was the most frequent location injured(31%)and was more likely to be accidental than proximal injuries(P=0.003).Air rifes were the most common firearm type used(56%).Pistols were implicated in 47(26%)cases,rifles in 17(9%),*** in 10(6%).Ninety-nine(55%)patients had procedures in the operating *** most frequent procedure was foreign body removal(55%).Conclusions Risk factors such as male sex,W hite-not Hispanic or Latino race/ethnicity,and adolescent age were attributed to increased risk for *** sex was associated with increased risk of injury by accidental discharge and female sex with intentional *** rifles were the most common firearm type overall,although female sex was associated with increased risk for injury by powder weapon.

关键词： firearm Injury Pediatric Trauma Upper extremity

Advances in lower extremity peripheral nerve surgery

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Plastic and Aesthetic Research 2023年第1期10卷 513-528页

作者： Anna Garbuzov Ramin Shekouhi d.spencer Nichols Harvey Chim University of Queensland-Ochsner Clinical School JeffersonLA 70121USA College of Medicine University of FloridaGainesvilleFloridaFL 32610USA division of Plastic and Reconstructive Surgery Department of SurgeryUniversity of Florida College of MedicineGainesvilleFloridaFL 32610USA Lilian S.Wells department of Neurosurgery University of Florida College of MedicineGainesvilleFloridaFL 32610USA

Peripheral nerve injury(PNI)is a common source of pain and disability in *** many patients are affected by PNI,peripheral nerve surgery advancements in the lower extremity have lagged behind the upper ***,principles that have demonstrated success in the upper extremity have been implemented in the lower *** with recent advances include the advent of novel nerve transfers in the lower extremity and using stem cells and electrical stimulation(ES)for nerve *** article focuses on advances in nerve transfers for lower extremity PNI and provides details on the basic science and clinical applications of newer interventions.

关键词： Stem cells peripheral nerve surgery nerve transfer electrical stimulation nerve repair nerve regeneration

Spectral/hp element methods:Recent developments, applications, and perspectives

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Journal of Hydrodynamics 2018年第1期30卷 1-22页

作者： Hui Xu Chris d.Cantwell Carlos Monteserin Claes Eskilsson Allan P.Engsig-Karup spencer J.Sherwin department of Aeronautics Imperial College London department of Applied Mathematics and Computer Science Technical University of Denmark department of Civil Engineering Aalborg University division Safety and Transport Research Institutes of Sweden (RISE) Center for Energy Resources Engineering (CERE) Technical University of Denmark

The spectral/hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomial basis functions on coarse finite element-type meshes. The spatial approximation is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials,modified to accommodate a C~0-continuous expansion. Computationally and theoretically, by increasing the polynomial order p,high-precision solutions and fast convergence can be obtained and, in particular, under certain regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral/hp element method and provides an overview of its application to computational fluid dynamics. In particular, it focuses on the use of the spectral/hp element method in transitional flows and ocean engineering. finally, some of the major challenges to be overcome in order to use the spectral/hp element method in more complex science and engineering applications are discussed.

关键词： High-precision spectral/hp elements continuous Galerkin method discontinuous Galerkin method implicit large eddy simulation

Cs_(3)Bi_(2)l_(9)-hydroxyapatite composite waste forms for cesium and iodine immobilization

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Journal of Advanced Ceramics 2022年第5期11卷 712-728页

作者： Kun YANG Yachun WANG Junhua SHEN spencer M.SCOTT Brian J.RILEY John d.VIENNA Jie LIAN department of Mechanical Aerospaceand Nuclear EngineeringRensselaer Polytechnic InstituteTroyUSA department of Materials Science&Engineering Rensselaer Polytechnic InstituteTroyUSA Savannah River National Laboratory AikenUSA Pacific Northwest National Laboratory RichlandUSA

Perovskite-based ceramic composites were developed as potential waste form materials for immobilizing cesium(Cs)and iodine(I)with high waste loadings and chemical *** perovskite Cs_(3)Bi_(2)I_(9)has high Cs(22 wt%)and I(58 wt%)content,and thus can be used as a potential host phase to immobilize these critical *** this work,the perovskite Cs_(3)Bi_(2)I_(9)phase was synthesized by a cost effective solution-based approach,and was embedded into a highly durable hydroxyapatite matrix by spark plasma sintering to form dense ceramic composite waste *** chemical durabilities of the monolithic Cs_(3)Bi_(2)I_(9)and Cs_(3)Bi_(2)I_(9)-hydroxyapatite composite pellets were investigated by static and semi-dynamic leaching tests,*** and I are incongruently released from the matrix for both pure Cs_(3)Bi_(2)I_(9)and composite *** normalized Cs release rate is faster than that of I,which can be explained by the difference in the strengths between Cs-I and Bi-I bonds as well as the formation of insoluble micrometer-sized BiOI *** activation energies of elemental releases based on dissolution and diffusion-controlled mechanisms are determined with significantly higher energy barriers for dissolution from the composite versus that of the monolithic Cs_(3)Bi_(2)I_(9).The ceramic-based composite waste forms exhibit excellent chemical durabilities and waste loadings,commensurate with the state-of-the-art glass-bonded perovskite composites for I and Cs immobilization.

关键词： cesium(Cs) iodine(Ⅰ) perovskite nuclear waste hydroxyapatite

Sulfidation and selenidation of nickel nanoparticles

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Carbon Energy 2021年第4期3卷 582-589页

作者： Brian B.Lynch Andrew P.Kelliher Bryan d.Anderson Alexander Japit Michael A.spencer Mehedi H.Rizvi Mehmet f.Sarac Veronica Augustyn Joseph B.Tracy department of Materials Science and Engineering North Carolina State UniversityRaleighNorth CarolinaUSA

NPs using elemental sulfur,1-hexadecanthiol,thiourea,trioctylphosphine sulfide,elemental selenium,and *** maintaining mole ratios of 2 mmol sulfur/selenium precursor:mmol Ni,products with phases of Ni_(3)S_(2),Ni_(9)S_(8),NiS,NiSO_(4)·6H_(2)O,Ni_(3)S_(4),Ni_(3)Se_(2),and NiSe have been *** products have voids that form through the Kirkendall effect during *** relating the chemical properties of the precursors to the phases of the products have been *** some precursors contained phosphorus,there was no significant incorporation of phosphorus in any of the *** increase of the NP size during sulfidation and selenidation is consistent with *** application of Ni sulfide and selenide NPs as electrocatalysts for the hydrogen evolution reaction is also demonstrated.

关键词： conversion chemistry electrocatalysis nanoparticles nickel selenide sulfide

The role of MT1-MMP in the progression and metastasis of osteosarcoma

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Journal of Cancer Metastasis and Treatment 2022年第1期8卷 564-578页

作者： Hannah L.M.spencer Steven d.Shnyder Paul M.Loadman Robert A.falconer Institute of Cancer Therapeutics Faculty of Life SciencesUniversity of BradfordBradford BD71DPUK

The dysregulation of Membrane-type 1 matrix metalloproteinase(MT1-MMP)has been extensively studied in numerous cancer types,and plays key roles in angiogenesis,cancer progression,and ***1-MMP is a predictor of poor prognosis in osteosarcoma(OS),yet the molecular mechanisms of disease progression are *** review provides a summary of the literature relating to the gene and protein expression of MT1-MMP(MMP-14)in OS clinical samples,evaluates the expression in cell lines and experimental models,and analyses its potential role in the progression and metastasis of *** addition,the therapeutic potential of MT1-MMP as a drug target has been *** to the biological complexity of MMPs,inhibition has proven to be ***,exploiting the expression and proteolytic capacity of MT1-MMP could open new avenues in the search for novel,safer and selective drugs for use in OS.

关键词： Matrix metalloproteinase membrane-type osteosarcoma MT1-MMP