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Mass-Stiffness Templates for Cubic Structural Elements Dedicated to Professor Karl Stark Pister for his 95th birthday

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Computer Modeling in Engineering & Sciences 2021年第12期129卷 1209-1241页

作者： carlos A.Felippa Department of Aerospace Engineering Sciences and Aerospace Mechanics Research Center University of Colorado at BoulderBoulderCO 80309-0429USA

1 This paper considers Lagrangian finite elements for structural dynamics constructed with cubic displacement shape *** method of templates is used to investigate the construction of accurate mass-stiffness *** method introduces free parameters that can be adjusted to customize elements according to accuracy and rank-sufficiency ***-and two-dimensional Lagrangian cubic elements with only translational degrees of freedom(DOF)carry two additional nodes on each side,herein called side nodes or *** usually placed at the third-points,the SN location may be adjusted within geometric *** adjustment effect is studied in detail using symbolic computations for a bar *** best SN location is taken to be that producing accurate approximation to the lowest natural frequencies of the continuum *** is investigated through Fourier analysis of the propagation of plane waves over a regular infinite lattice of bar *** is placed on the acoustic branch of the frequency-vs.-wavenumber dispersion *** is found that dispersion results using the fully integrated consistent mass matrix(CMM)are independent of the SN location whereas its lowfrequency accuracy order is O(κ8),whereκis the dimensionless wave *** the diagonally lumped mass matrix(DLMM)constructed through the HRZ scheme,two optimal SN locations are identified,both away from third-points and of accuracy order O(κ8).That with the smallest error coefficient corresponds to the Lobatto 4-point integration rule.A special linear combination of CMM and DLMM with nodes at the Lobatto points yields an accuracy of O(κ10)without any increase in the computational effort over *** effect of reduced integration(RI)on both mass and stiffness matrices is also *** is shown that singular mass matrices can be constructed with 2-and 3-point RI rules that display the same optimal accuracy of the exactly integrated case,at the cost of introducing spurious modes

关键词： Structural dynamics Lagrangian elements finite elements cubic shape functions bar plane stress mass stiffness vibration wave propagation Fourier analysis dispersion templates

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Development and application of an interface constitutive model for fully grouted rock-bolts and cable-bolts

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第4期13卷 811-819页

作者： Emad Jahangir Laura.blanco-Martin Faouzi Hadj-Hassen Michel Tijani MINES ParisTech PSL Research UniversityDepartment of Geosciences35 Rue Saint Honoré77300FontainebleauFrance

This paper proposes a new interface constitutive model for fully grouted rock-bolts and cable-bolts based on pull-out test results.A database was created combining published experimental data with in-house *** means of a comprehensive framework,a Coulomb-type failure criterion accounting for friction mobilization was *** the elastic phase,in which the interface joint is not yet created,the proposed model provides zero radial displacement,and once the interface joint is created,interface dilatancy is modeled using a non-associated plastic potential inspired from the behavior of rock *** results predicted by the proposed model are in good agreement with experimental *** model has been implemented in a finite element method(FEM)code and numerical simulations have been performed at the elementary and the structural *** results obtained provide confidence in the ability of the new model to assist in the design and optimization of bolting patterns.

关键词： Fully grouted bolts Interface constitutive model Dilatancy Pull-out tests Finite element method(FEM)modeling

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Stability analysis of the fluttering and autorotation of flow-induced rotation of a hinged flat plate

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Journal of Hydrodynamics 2013年第5期25卷 755-762页

作者： MIRZAEISEFAT Sina FERNANDES Antonio carlos Department of Naval Architecture and Marine Engineering University of Michigan COPPE/UFRJ Federal University of Rio de Janeiro

This work describes investigations performed on the interaction of uniform current and freely rotating plate about a fixed vertical axis. Fluttering and autorotation are two different motions that may occur during the flow induced rotation. The dimensional analysis proves that the motion in flow induced rotation motion is governed essentially by the dimensionless moment of inertia and Reynolds number. Certain combinations define the stability boundaries between fluttering and autorotation. Fluttering is oscillation of body about a vertical axis and the autorotation is a name given to the case when the body turns continuously about the vertical axis First, the loads and moment coefficients are calculated by experiments and streamline theory for different angles of attack for a fixed fiat plate. Then for dynamic case, a bifurcation diagram is presented based on experiments to classify different motion states of flow induced rotation. Finally, a dynamical model is proposed for stability analysis of flow induced rotation of a flat plate.

关键词： flow-induced rotation autorotation fluttering stability analysis

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Tricuspid valve avulsion

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Journal of Geriatric Cardiology 2023年第4期20卷 317-318页

作者： Abhinav Karan Anamarys blanco Emil Missov Srinivasan Sattiraju Internal Medicine University of Florida College of Medicine-JacksonvilleFloridaUSA Department of Cardiology University of Florida College of Medicine-JacksonvilleFloridaUSA

A 71-year-old male with a medical history of sick sinus syndrome with dual-chamber pacemaker system implantation six years prior,and hypertension presented to the emergency department with complaints of generalized ma... 详细信息

关键词： hypertension implantation fever

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Phenomenological model for torsional galloping of an elastic flat plate due to hydrodynamic loads

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Journal of Hydrodynamics 2014年第1期26卷 57-65页

作者： FERNANDES Antonio carlos ARMANDEI Mohammadmehdi Department of Naval and Ocean Engineering COPPE/UFRJ

This study investigates the torsional galloping phenomenon, an instability type flow-induced oscillation, in an elastic stru-cture due to hydrodynamic loads into the water current. The structure applied here is a rectangular flat plate with an elastic axis in its mid-chord length. The elasticity is provided by torsion spring. The flat plate has only one degree of freedom which is rotation in pure yaw about its axis. It is observed that as the current speed is higher than a critical velocity, the flat plate becomes unstable. The instability leads to torsional galloping occurrence, as a result of which the flat plate begins to yaw about the elastic axis. By testing two different chord lengths each with several torsion spring rates, the flat plate behavior is investigated and three different responses are recognized. Then, a phenomenological model is developed with the original kernel in the form of the van der Pol-Duffing equa-tion. The model explains these three responses observed experimentally.

关键词： torsional galloping flow-induced oscillation phenomenological model van der Pol-Duffing equation

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Evaluating host plant resistance in cotton (Gossypium hirsutumL.) with varying gland densities to tobacco budworm (Heliothis virescensF.) and bollworm (Helicoverpa zeaBoddie) in the field and laboratory

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Agricultural Sciences 2012年第1期3卷 14-23页

作者： Jodi A. Scheffler Gabriela B. Romano carlos A. blanco Crop Genetics Research Unit United States Department of Agriculture—Agricultural Research Service (USDA-ARS) Stoneville USA Southern Insect Management Research Unit USDA-ARS Stoneville USA

Cotton (Gossypium hirsutum L.) produces a number of toxic terpenoid aldehyde (TA) compounds contained in epidermal glands that help protect the plant from pests and diseases. In the seed, one of these toxic compounds, gossypol, limits the use of the seed to ruminants such as dairy cows. There are breeding techniques and germplasm available to decrease gossypol in the seed, but the breeding process also needs to include methods to evaluate the plant’s ability to resist insect pests. Three approaches were used to assess resistance of cotton to herbivory from bollworm (Helicoverpa zea Boddie) and tobacco budworm (Heliothis virescens F.) including field counts, controlled field antibiosis assays and laboratory feeding tests of young field grown leaves. Results indicated that both field and laboratory evaluation could provide an assessment of the cotton host’s resistance. Measurements of terpenoid aldehydes (TAs) in the seed and the leaves, confirmed that the levels and types of TAs in the seed were not always good estimators of leaf TAs and that other TAs such as hemigossypolone and heliocides contribute to host plant resistance.

关键词： Cotton Gossypol Helicoverpa Heliothis Terpenoid Aldehydes Host Plant Resistance

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Optimal Positioning Strategy for Multi-Camera Zooming Drones

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IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1802-1818页

作者： Manuel Vargas carlos Vivas Teodoro Alamo Department of System Engineering and Automation University of SevilleSeville 41092Spain

In the context of multiple-target tracking and surveillance applications,this paper investigates the challenge of determining the optimal positioning of a single autonomous aerial vehicle or agent equipped with multiple independently-steerable zooming cameras to effectively monitor a set of targets of *** camera is dedicated to tracking a specific target or cluster of *** key innovation of this study,in comparison to existing approaches,lies in incorporating the zooming factor for the onboard cameras into the optimization *** enhancement offers greater flexibility during mission execution by allowing the autonomous agent to adjust the focal lengths of the onboard cameras,in exchange for varying real-world distances to the corresponding targets,thereby providing additional degrees of freedom to the optimization *** proposed optimization framework aims to strike a balance among various factors,including distance to the targets,verticality of viewpoints,and the required focal length for each *** primary focus of this paper is to establish the theoretical groundwork for addressing the non-convex nature of the optimization problem arising from these *** this end,we develop an original convex approximation *** paper also includes simulations of diverse scenarios,featuring varying numbers of onboard tracking cameras and target motion profiles,to validate the effectiveness of the proposed approach.

关键词： Convex optimization projective transformation unmanned aerial vehicle visual object tracking visual surveillance.

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Bresse Beam with Damping and Logarithmic Source

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Chinese Annals of Mathematics,Series B 2024年第5期45卷 685-702页

作者： Sebastiao CORDEIRO carlos BALDEZ carlos RAPOSO Ducival PEREIRA Octavio VERA Department of Mathematics Federal University of ParaAbaetetubaParaBrazil Department of Mathematics Federal University of ParaBragancaParaBrazil Department of Mathematics Federal University of ParaSalinopolisParaBrazil Department of Mathematics State University of ParaBelemParaBrazil Department of Mathematics University of TarapacaAricaChile

This paper investigates the stabilization of a Bresse system with internal damping and logarithmic *** authors use the potential well *** initial data in the stability set created by the Nehari surface,the existence of a global solution is proved by using Faedo-Galerkin's *** Nakao theorem gives the exponential decay.A numerical approach is presented to illustrate the results obtained.

关键词： Bresse beam Logarithmic source Global solution Exponential decay Numerical approach

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Air Pollution, Government Pollution Regulation, and Industrial Production in China

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Journal of Systems Science & Complexity 2020年第4期33卷 1064-1079页

作者： CAO Dong RAMIREZ carlos D. School of Economics and Management Xidian UniversityXi’an 710071China Department of Economics George Mason UniversityFairfaxVAUnited States

Over the last four decades,a severe deterioration in air quality has accompanied China’s rapid *** a result,the Chinese government has implemented stricter policies and regulation to control air *** this paper,the authors create a measure of government policies on air pollution by tracking all pollution-related government announcements in Chinese *** authors then use this variable,along with measures of actual pollution,to investigate how air pollution,industrial production,and government policies on air pollution are *** authors conduct this investigation nationwide,as well as in five large cities in China.A vector autoregression model suggests that,nationwide,government policies seem to decrease air pollution without significantly affecting industrial ***,the effect appears to be short-lived,dissipating after a few *** addition,the authors find that the dynamic relationship among these variables differs by *** instance,following an adverse air quality shock in Beijing,government efforts to control pollution seem to have an ameliorating city-wide effect,decreasing local air pollution in subsequent *** Shanghai and Guangzhou,while the local government reacts to adverse air pollution shocks,the ameliorating effects are not statistically *** Chengdu and Shenyang,the authors detect no significant local government reaction to adverse air pollution ***,in these cities,local government policies do not impart a statistically measurable effect on air pollution.

关键词： pollution. pollution nationwide

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Spectral signatures of hydrilla from a tank and field setting

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Frontiers of Earth Science 2012年第4期6卷 453-460页

作者： Alfonso blanco John J. QU William E. ROPER George Mason University College of Science Department of Geography and Geoinforrnation Sciences 4400 University Drive Fairfax VA 22030 USA

The invasion of hydrilla in many waterways has caused significant problems resulting in high main- tenance costs for eradicating this invasive aquatic weed. Present identification methods employed for detecting hydrilla invasions such as aerial photography and videos are difficult, costly, and time consuming. Remote sensing has been used for assessing wetlands and other aquatic vegetation, but very little information is available for detecting hydrilla invasions in coastal estuaries and other water bodies. The objective of this study is to construct a library of spectral signatures for identifying and classifying hydrilla invasions. Spectral signatures of hydrilla were collected from an experimental tank and field locations in a coastal estuary in the upper Chesapeake Bay. These measurements collected from the experimental tank, resulted in spectral signatures with an average peak surface reflectance in the near-infrared （NIR） region of 16% at a wavelength of 818 nm. However, the spectral measure- ments, collected in the estuary, resulted in a very different spectral signature with two surface reflectance peaks of 6% at wavelengths of 725 nm and 818 nm. The difference in spectral signatures between sites are a result of the components in the water column in the estuary because of increased turbidity （e.g., nutrients, dissolved matter and suspended matter）, and canopy being lower （submerged） in the water column. Spectral signatures of hydrilla observed in the tank and the field had similar characteristics with low reflectance in visible region of the spectrum from 400 to 700 nm, but high in the NIR region from 700 to 900 nm.

关键词： Chesapeake Bay hydrilla spectral library spectral signatures near-infrared NDVI

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