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2013

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Articles 1501 - 1513 of 1513

Full-Text Articles in Civil and Environmental Engineering

Position Control Of Electro-Hydraulic Actuator System Using Fuzzy Logic Controller Optimized By Particle Swarm Optimization, Daniel M. Wonohadidjojo, Ganesh Kothapalli, Mohammed Hassan Jan 2013

Position Control Of Electro-Hydraulic Actuator System Using Fuzzy Logic Controller Optimized By Particle Swarm Optimization, Daniel M. Wonohadidjojo, Ganesh Kothapalli, Mohammed Hassan

Research outputs 2014 to 2021

The position control system of an electro-hydraulic actuator system (EHAS) is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system: the friction and the internal leakage. A variable load that simulates a realistic load in robotic excavator is taken as the trajectory reference. A method of control strategy that is implemented by employing a fuzzy logic controller (FLC) whose parameters are optimized using particle swarm optimization (PSO) is proposed. The scaling factors of the fuzzy inference system are tuned to obtain the optimal values which yield the best system performance. The simulation …

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Characterization Of A Coal Fly Ash-Cement Slurry By The Absolute Foam Index, Melanie Kueber Watkins Jan 2013

Characterization Of A Coal Fly Ash-Cement Slurry By The Absolute Foam Index, Melanie Kueber Watkins

Dissertations, Master's Theses and Master's Reports

This dissertation established a standard foam index: the absolute foam index test. This test characterized a wide range of coal fly ash by the absolute volume of air-entraining admixture (AEA) necessary to produce a 15-second metastable foam in a coal fly ashcement slurry in a specified time. The absolute foam index test was used to characterize fly ash samples having loss on ignition (LOI) values that ranged from 0.17 to 23.3 %wt. The absolute foam index characterized the fly ash samples by absolute volume of AEA, defined as the amount of undiluted AEA solution added to obtain a 15-minute endpoint …

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Futures Methodology As An Analysis And Planning Tool Within The Commercial Real Estate Industry, An Interpretative Study, Dominika Brodowicz Jan 2013

Futures Methodology As An Analysis And Planning Tool Within The Commercial Real Estate Industry, An Interpretative Study, Dominika Brodowicz

Doctoral

Currently, the majority of methods used in the commercial real estate analysis and planning processes have retrospective and quantitative roots and are based on historic data and trend extrapolation. This approach is based on the assumption that the relationships among key commercial property market variables and trends are constant and develop in a predictable manner into the future. Meanwhile, contemporary real estate companies, which are the subject of this study, are faced with rapid change, often of a discontinuous nature, in their external and internal environments. Furthermore, some of the challenges facing this industry, like social sustainability and a shift …

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On The Concept Of Earthquake Resistant Hybrid Steel Frames, Seyed Mohammad Razavi Jan 2013

On The Concept Of Earthquake Resistant Hybrid Steel Frames, Seyed Mohammad Razavi

Civil Engineering Dissertations - Archive

The concept of hybrid steel frame system is presented in which mixtures of fully-rigid and semi-rigid steel connections are used in the 3-, 9- and 20-story SAC frames. Several different patterns and locations of semi-rigid connection replacements within the frame are examined in order to identify hybrid frames with the best seismic performance. The effective connection stiffness is identified by performing a parametric study on the initial stiffness of the semi-rigid connections. Then, the cyclic behavior of the connections with the most effective stiffness is obtained using nonlinear finite element analysis. Inelastic dynamic analyses are conducted on the proposed selected …

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The Uplift Resistance Of Spartina Alterniflora In A Louisiana Salt Marsh, James Madison Bouanchaud Iii Jan 2013

The Uplift Resistance Of Spartina Alterniflora In A Louisiana Salt Marsh, James Madison Bouanchaud Iii

LSU Master's Theses

The uprooting resistance of Spartina Alterniflora was measured in Terrebonne Bay and Bay Jimmy, both of which are located in Louisiana. The parameters collected included plant uprooting resistance, stem diameter, and stem height. Seasonal variations and site specific properties were considered. A device was designed and constructed that was able to perform the specific testing under the constraints of the field site. The device consisted of a winch mounted to a tripod and connected to an inline load cell to measure the uprooting resistance. The data sets were analyzed to determine the relationship between the uprooting resistance and the physical …

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Documenting Postural Changes And Repetition Among Violin Players And Their Influence In The Development Of Musculoskeletal Disorders, Cristina Handal Jan 2013

Documenting Postural Changes And Repetition Among Violin Players And Their Influence In The Development Of Musculoskeletal Disorders, Cristina Handal

LSU Master's Theses

The objective of this study was to document the changes in posture and the number of wrist and forearm repetitions among violin/viola players during an experiment session to attempt to understand the development of musculoskeletal disorders. Also, the perception of discomfort and pain felt by the violin/viola players in the past and the number that had been diagnosed with a disorder was documented. Finally, possible correlations were calculated between pain/discomfort with variables like the number of years playing the violin, hours of practice/day, frequency of pain, gender, and dominant hand and among different pain/discomfort variables (pain/discomfort before the experiment, after …

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Biofilter Treatment Of Gas Phase Β-Caryophyllene At Elevated Temperature, Yiying Yue Jan 2013

Biofilter Treatment Of Gas Phase Β-Caryophyllene At Elevated Temperature, Yiying Yue

LSU Master's Theses

Industrial wood processing operations generate a variety of gaseous emissions containing volatile organic compounds (VOCs). One of the VOCs emitted from the processing of coniferous softwood tree species is β-caryophyllene, a naturally occurring sesquiterpene of environmental concern. One approach that may be attractive for treating gaseous emissions of β-caryophyllene from wood processing operations is the use of fixed-film processes commonly referred to as biofiltration. Previously, it was established that β-caryophyllene can be successfully treated via biofiltration at temperatures in the mesophilic range. Many gaseous emissions from industrial wood processing operations, however, are higher in temperature than those employed in the …

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Characterization And Uncertainty Analysis Of Siliciclastic Aquifer-Fault System, Ahmed Saad Elshall Jan 2013

Characterization And Uncertainty Analysis Of Siliciclastic Aquifer-Fault System, Ahmed Saad Elshall

LSU Doctoral Dissertations

The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana, USA, is fluvial in origin. The east-west trending Baton Rouge fault and Denham Springs-Scotlandville fault cut across East Baton Rouge Parish and play an important role in groundwater flow and aquifer salinization. To better understand the salinization underneath Baton Rouge, it is imperative to study the hydrofacies architecture and the groundwater flow field of the Baton Rogue aquifer-fault system. This is done through developing multiple detailed hydrofacies architecture models and multiple groundwater flow models of the aquifer-fault system, representing various uncertain model propositions. The hydrofacies architecture models focus on …

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Framework Of Damage Detection In Vehicle-Bridge Coupled System And Application To Bridge Scour Monitoring, Xuan Kong Jan 2013

Framework Of Damage Detection In Vehicle-Bridge Coupled System And Application To Bridge Scour Monitoring, Xuan Kong

LSU Doctoral Dissertations

Most vibration-based damage identification methods make use of measurements directly from bridge structures with attached sensors. However, the vehicle moving on the bridge can serve as both an active actuator and a response receiver. This dissertation aimed to develop new methodologies to eventually detect bridge damages such as scour using the dynamic response of the vehicle. To reach the final objective, a framework of damage identification was developed first, which gave a guideline on the three crucial steps for damage detection. An optimization method was proposed that combines the Genetic Algorithm (GA) and the First Order (FO) method. It has …

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Modeling Temporal And Spatial Variations In Dissolved Oxygen In Amite River, Vahid Zahraeifard Jan 2013

Modeling Temporal And Spatial Variations In Dissolved Oxygen In Amite River, Vahid Zahraeifard

LSU Doctoral Dissertations

A watershed-based modeling framework is developed in this dissertation for simulating temporal and spatial variations in DO in lowland rivers with organic-rich fine-grained sediment. The modeling framework is based on three major contributions/new models, including (1)VART-DO model for improved estimation of reaeration coefficient (K2) in natural streams, (2)VART-DOS model for simulation of temporal variations in DO in response to sediment resuspension, and (3)VART DO-3L model for simulation of spatial variations in DO. A major advantage of VART-DO model is the capability of simulating DO exchange across the water-sediment interface through the hyporheic exchange mechanism in addition to the air-water exchange. …

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Nanoindentation Characterization Of Clay Minerals And Clay-Based Hybrid Bio-Geomaterials, Rohit Raj Pant Jan 2013

Nanoindentation Characterization Of Clay Minerals And Clay-Based Hybrid Bio-Geomaterials, Rohit Raj Pant

LSU Doctoral Dissertations

Layered hydrous aluminosilicates are key constituent minerals in rocks, soils, and other parts of the Earth crust. Understanding mechanical properties of these aluminosilicates is crucial for seismic study, stability of parent rocks and geomaterials, and for geophysical subsurface exploration. Recently, growing prospects of clay based nanocomposites have renewed further interest in understanding the fundamental elastic and plastic properties of hydrous aluminosilicates. Their distinct, nanoscale layered crystal structure is known to result in anisotropic responses to loading, however, owing to their tiny sizes; it is a significant challenge to determine the anisotropic properties. There is a little data available in the …

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Bioremediation Of Chlorinated Ethanes And Ethenes In Vertical Flow Engineered Wetland Systems, Christopher Akudo Jan 2013

Bioremediation Of Chlorinated Ethanes And Ethenes In Vertical Flow Engineered Wetland Systems, Christopher Akudo

LSU Doctoral Dissertations

Sustainable treatment of chlorinated ethanes and ethenes contaminated groundwater using vertical flow engineered wetland systems were investigated in microcosm and column studies. Experiments on environmental and biogeochemical factors that affect system performance were conducted, and a numerical model involving advection, sorption, and sequential biodegradation was developed to describe the fate and transport of the contaminants of concern in the treatment wetland bed. 1,1-dichloroethane (1,1-DCA) and cis-1,2-dichloroethene (cis-1,2-DCE) were used as the chemicals of interest. The presence of cis-1,2-DCE inhibited dechlorination of 1,1-DCA but cis-1,2-DCE dechlorination was not affected by the presence of 1,1-DCA. Simulation runs showed that the treatment bed …

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Effect Of Support Compliance On The Resonant Behavior Of Microcantilever-Based Sensors In Viscous Fluids, Rabin Maharjan Jan 2013

Effect Of Support Compliance On The Resonant Behavior Of Microcantilever-Based Sensors In Viscous Fluids, Rabin Maharjan

Dissertations (1934 -)

Resonant microcantilevers are often considered for use in chemical sensing and biosensing applications. However, when excited in the conventional transverse flexural mode, their performance in liquids is severely compromised. Theoretical and experimental studies have shown that the detrimental effects of the liquid may be mitigated by operating the microcantilever in lateral flexure, especially for microbeams having smaller length-to-width (L/b) ratios. However, for these most promising geometries the predictions of existing models tend to diverge from experimental data for resonant frequency (fres) and quality factor (Q). A likely reason for these discrepancies is support compliance, which has been neglected …

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