Architectural Engineering Commons^™

Ventilation Rates And Airflow Pathways In Patient Rooms: A Case Study Of Bioaerosol Containment And Removal, Ehsan S. Mousavi, Kevin R. Grosskopf

Durham School of Architectural Engineering and Construction: Faculty Publications

Most studies on the transmission of infectious airborne disease have focused on patient room air changes per hour (ACH) and how ACH provides pathogen dilution and removal. The logical but mostly unproven premise is that greater air change rates reduce the concentration of infectious particles and thus, the probability of airborne disease transmission. Recently, a growing body of research suggests pathways between pathogenic source (patient) and control (exhaust) may be the dominant environmental factor. While increases in airborne disease transmission have been associated with ventilation rates below 2 ACH, comparatively less data are available to quantify the benefits of higher …

Adaptive Predictive Functional Controller, Fadi Alsaleem, Arvind Rao

Durham School of Architectural Engineering and Construction: Faculty Publications

A controller device and a method for controlling a system that utilizes an adaptive mechanism to self-learn the system char acteristics and incorporates this adaptive self-learning ability to predict a control parameter correctly to provide precise control of a system component.

An Adaptive Photovoltaic Topology To Overcome Shading Effect In Pv Systems, Mohamed Amer Chaaban, Lana El Chaar, Mahmoud Alahmad

Durham School of Architectural Engineering and Construction: Faculty Publications

Shading in photovoltaic systems can cause many undesired effects.When shading occurs, the power generated from the PV system is much less than nominal power, increasing the electrical mismatching losses between PV system components. Active research to address this power loss focuses on static and adaptive systems.This paper addresses an adaptive system solution and proposes a new method to adaptively overcome losses due to shading during low radiation conditions. In addition, a statistical analysis for choosing the most feasible and efficient configuration for the system size is presented. The proposed system has been validated under shade conditions in a simulation and …

Building Envelope And Interior Grading Systems And Methods, Fadi Mohammad Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

A difference module determines differences between an out door ambient temperature and an indoor temperature, deter mines a first average of the differences, and determines a second average of the differences. A storing module stores a first data point, the first data point including the first average and a first total run time of a heating, ventilation, and/or air conditioning (HVAC) system, and stores a second data point, the second data point including the second average and a second total run time of the HVAC system. A fitting module fits a line to the first and second data points. An …

A Shear-Based Parameterization Of Turbulent Mixing In The Stable Atmospheric Boundary Layer, Jordan M. Wilson, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, shear-based parameterizations of turbulent mixing in the stable atmospheric boundary layer (SABL) are proposed. A relevant length-scale estimate for the mixing length LM of the turbulent momentum field is constructed from the turbulent kinetic energy Ek and the mean shear rate S as. Using observational data from two field campaigns-the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment and the 1999 Cooperative Atmosphere-Surface Exchange Study (CASES-99)- is shown to have a strong correlation with LM. The relationship between LM and corresponds to the ratio of the magnitude of the tangential components of the turbulent momentum flux …

Hydraulic Design Of Baffles In Disinfection Contact Tanks, Zachary H. Taylor, Jeremy S. Carlston, Subhas Karan Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study focuses on understanding the hydraulic design of baffled contact tanks using computational fluid dynamics simulations. In particular, we address the key question: for a given footprint of a rectangular tank with a specified inlet width (Winlet), how does the hydraulic efficiency of a baffled tank depend on the configuration of internal baffles? In an effort to address this question, a carefully conceived parametric study consisting of 30 high-resolution two-dimensional (planar) simulations was conducted to quantify the hydraulic efficiency of a laboratory scale tank as a function of dimensional relationships between key baffle design dimensions (baffle opening length Lbo, …

Model For Consolidation Analysis Of Layered Soils Under Depth-Dependent Loading, Hefu Pu, Patrick J. Fox

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A numerical model is presented for one-dimensional large strain consolidation of a layered soil stratum. The algorithm accounts for vertical strain, soil self-weight, conventional constitutive relationships, changing material properties during consolidation, unload/reload, time-dependent loading and boundary conditions, an externally applied hydraulic gradient, and multiple soil layers with different material properties. The model can also accommodate depth-dependent loading and variable preconsolidation stress profiles. Verification checks of the model show excellent agreement with available analytical and numerical solutions for consolidation of soils with multiple layers and depth-dependent loading. An overview of this model is presented, and a parametric study is performed to …

A Review Of Approaches For Sensing, Understanding, And Improving Occupancy-Related Energy-Use Behaviors In Commercial Buildings, Hamed Nabizadeh Rafsanjani, Changbum R. Ahn, Mahmoud Alahmad

Durham School of Architectural Engineering and Construction: Faculty Publications

Buildings currently account for 30–40 percent of total global energy consumption. In particular, commercial buildings are responsible for about 12 percent of global energy use and 21 percent of the United States’ energy use, and the energy demand of this sector continues to grow faster than other sectors. This increasing rate therefore raises a critical concern about improving the energy performance of commercial buildings. Recently, researchers have investigated ways in which understanding and improving occupants’ energy-consuming behaviors could function as a cost-effective approach to decreasing commercial buildings’ energy demands. The objective of this paper is to present a detailed, up-to-date …

Use Of Fiber-Reinforced Cements In Masonry Construction And Structural Rehabilitation, Ece Erdogmus

Durham School of Architectural Engineering and Construction: Faculty Publications

The use of fiber reinforcement in traditional concrete mixes has been extensively studied and has been slowly finding its regular use in practice. In contrast, opportunities for the use of fibers in masonry applications and structural rehabilitation projects (masonry and concrete structures) have not been as deeply investigated, where the base matrix may be a weaker cementitious mixture. This paper will summarize the findings of the author’s research over the past 10 years in these particular applications of fiber reinforced cements (FRC). For masonry, considering both mortar and mortar-unit bond characteristics, a 0.5% volume fraction of micro fibers in type …

Performance Analysis And Modelling Of Hybrid Photovoltaic-Thermal Solar Panels, Nicole C. Annis

Doctoral Dissertations

A photovoltaic-thermal (PVT) panel was constructed, tested, and modelled using both MATLAB and TRNSYS. During the experimental testing, which took place on the Missouri University of Science and Technology campus in Rolla, Missouri; two identical PVT panels were tested alongside two PV panels to gather an electrical baseline for comparison. Approximately 69 days’ worth of data were of data were collected during the summer of 2014. The PV electrical, PVT electrical, PVT thermal and PVT combined (electrical and thermal) efficiencies were 3.5-5.6%, 3.4-5.4%, 20.9-11.6%, and 24.3-17.0%, respectively.

A MATLAB program was developed using existing equations for one-dimensional, quasi-steady model of …

A Revisit Of The Equilibrium Assumption For Predicting Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, we revisit the consequence of assuming equilibrium between the rates of production (P) and dissipation (∈) of the turbulent kinetic energy (k) in the highly anisotropic and inhomogeneous near-wall region. Analytical and dimensional arguments are made to determine the relevant scales inherent in the turbulent viscosity (νt) formulation of the standard k-∈ model, which is one of the most widely used turbulence closure schemes. This turbulent viscosity formulation is developed by assuming equilibrium and use of the turbulent kinetic energy (k) to infer the relevant velocity scale. We show that such turbulent viscosity formulations are not suitable …

Phytoscreening: A Comparison Of In Planta Portable Gc-Ms And In Vitro Analyses, Matt A. Limmer, Gregory D. Martin, Christopher J. Watson, Camilo Martinez, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Phytoscreening Has Been Proven to Rapidly Delineate Subsurface Contaminant Plumes for Semiquantitative Site Assessment, with Minimal Impact to Property or Ecology through the Collection and Analysis of Tree Cores. Here, Three Phytoscreening Methods Were Applied Concurrently to Identify Multiple Chlorinated Volatile Organic Compounds (CVOCs) in a Phytoremediation Treatment System at a Contaminated Industrial Facility. Tree Coring, in Planta Gas Chromatography-Mass Spectrometry (GC-MS), and in Planta Passive Sampling Showed General Agreement, with the in Planta GC-MS Providing the Quickest But Least Quantitative Results. the Portable GC-MS Sampling and Analysis Method Identified Six CVOCs in the Xylem of Hybrid Poplars (Populus Sp.) …

Laminar And Turbulent Regime Changes In Drinking Water Contact Tanks, Taylor C. Barnett, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Transitions in flow regimes that can occur in drinking water contact tanks may significantly affect the disinfection efficiency of the system. To demonstrate these effects, the authors investigated the internal velocity fields and flow regime of a drinking water contact tank located in Jamestown, Colo. The baffling factor (BF) of the system fluctuated annually between 0.5 and 0.6 because of a shift in flow regime caused by changes in the flow rate of the system. The authors studied the effects of the regime change from laminar to turbulent flow (or vice versa) using computational fluid dynamics (CFD) models and physical …

Factors Affecting The Seismic Behavior Of Segmental Precast Bridge Columns, Haitham Dawood, Mohamed Elgawady, Joshua Hewes

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This manuscript discusses the design parameters that potentially affect the lateral seismic response of segmental precast post-tensioned bridge piers. The piers consist of precast circular cross section segments stacked one on top of the other with concentric tendons passing through ducts made in the segments during casting. The bottommost segments of the piers were encased in steel tubes to enhance ductility and minimize damage. An FE model was used to investigate different design parameters and how they influence the lateral force — displacement response of the piers. Design parameters investigated included the initial post-tensioning stress as a percentage of the …

Finite Element Modelling And Dilation Of Frp-Confined Concrete Columns, Osama Youssf, Mohamed Elgawady, Julie E. Mills, Xing Ma

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Concrete dilation is one of the main parameters that controls the stress-strain behavior of confined concrete. Several analytical studies have been carried out to predict the stress-strain behavior of concrete encased in fiber-reinforced polymer (FRP), which is crucial for structural design. However, none of these studies have provided a simple formula to determine the dilation parameter that is always required in the finite element (FE) material modelling of concrete. This paper presents a simple empirical model predicting the confined concrete dilation parameter within the theoretical framework of a Karagozian and Case type concrete plasticity model. A set of 105 FRP-confined …

Assessment Of Noise-Induced Annoyance By Tones In Noise From Building Mechanical Systems, Joonhee Lee, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Prominent tones in noise generated by mechanical equipment in buildings can cause complaints from occupants in buildings. The ISO 1996-2 and ANSI S1.13 standards describe methodologies and metrics to quantify tonality perception, but the influence of tones in noise on human annoyance and performance is not fully understood yet. This paper investigates annoyance responses of humans while exposed to background noise with tonal components. Twenty participants completed digit span tasks while exposed to noise signals with differing levels of tones and overall loudness. Subjects were also asked to rate their annoyance after completing tasks under each noise signal. The subjective …

The Impact Of Building Acoustics On Speech Comprehension And Student Achievement, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

The movement for improved classroom acoustics has primarily been grounded on studies that show how building acoustics (i.e. background noise levels and room reverberation) affect speech intelligibility, as determined by speech recognition tests. What about actual student learning, though? If students do not understand each spoken word in the classroom perfectly, can they still manage to achieve high scholastic success? This presentation will review two recent studies conducted at the University of Nebraska – Lincoln, linking classroom acoustic conditions to student learning outcomes and speech comprehension (rather than simply recognition). In the first, acoustic measurements in two public school districts …

Effects Of Room Acoustics On Comprehension Of Foreign-Accented Speech By Native And Non-Native English-Speaking Listeners, Zhao Peng, Kristin E. Hanna, Brenna N. Boyd, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

In a previous study by the authors, reverberation time (RT) and background noise level (BNL) were both found to have negative effects on native and non-native English-speaking listeners in comprehending English speech produced by native American-English-speaking talkers. Comprehension scores were adjusted for listeners’ baseline English proficiency levels. In the present study, instead of native English-speaking talkers, two native Mandarin Chinese talkers (one male, one female) with similar English spoken proficiency were recruited to produce the same speech materials used in the previous study. A similar methodology was adopted to conduct speech comprehension tests on three groups of listeners: 1) native …

Ua66 Ogden College Of Science & Engineering Newsletter, Cheryl Stevens, Dean

Ogden College of Science & Engineering Publications

No abstract provided.

The Bridge Newsletter Winter 2014, Missouri University Of Science And Technology

The Bridge Newsletter

-Smart living
-Bodapati earns lifetime award
-TMS honors Myers
-Mays receives award for research

Phytomonitoring Of Chlorinated Ethenes In Trees: A Four-Year Study Of Seasonal Chemodynamics In Planta, Matt A. Limmer, Amanda J. Holmes, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Long-Term Monitoring (LTM) of Groundwater Remedial Projects is Costly and Time-Consuming, Particularly When using Phytoremediation, a Long-Term Remedial Approach. the Use of Trees as Sensors of Groundwater Contamination (I.e., Phytoscreening) Has Been Widely Described, Although the Use of Trees to Provide Long-Term Monitoring of Such Plumes (Phytomonitoring) Has Been More Limited Due to Unexplained Variability of Contaminant Concentrations in Trees. to Assess This Variability, We Developed an in Planta Sampling Method to Obtain High-Frequency Measurements of Chlorinated Ethenes in Oak (Quercus Rubra) and Baldcypress (Taxodium Distichum) Trees Growing above a Contaminated Plume during a 4-Year Trial. the Data Set Revealed …

Effect Of Placement Characteristics On Scc Lateral Pressure Variations, A. F. Omran, Y. M. Elaguab, Kamal Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Lateral pressure exerted by fresh concrete on vertical formwork systems controls significantly the design of the formwork systems. Several factors including, material properties, placement conditions, and formwork characteristics can affect formwork lateral pressure. This paper presents the results of an extensive experimental work aimed at studying the influence of concrete temperature (10-32 °C), casting depth (up to 13 m), placement rate (2-30 m/h), waiting period between successive lifts, as well as concrete thixotropy on lateral pressure characteristics. The increase of concrete temperature is shown to accelerate the stiffening rate of the concrete leading to reduction in initial lateral pressure. For …

Measurement Of Stiffness Anisotropy In Kaolinite Using Bender Element Tests In A Floating Wall Consolidometer, X. Kang, G. C. Kang, B. Bate

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A new floating wall consolidometer-type bender element testing system was developed to study the stiffness anisotropy of clays at applied vertical stresses up to 800 kPa. One-dimensional slurry-consolidated Georgia RP-2 kaolinite samples, prepared with 0.005 and 1 mol/l NaCl solutions, were tested in this system. A floating wall design eliminated the detrimental bending moment that acts upon the horizontally installed benders as a result of soil settlement in a traditional fixed wall setup, which significantly improved the signal quality and bender reuse. Floating wall-soil interface resistance was quantified with pulling tests. Analytical equations were then derived to calculate the wall …

The Quest For An Unambiguous Parameterization Of Mixing Efficiency In Stably Stratified Geophysical Flows, Benjamin D. Mater, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Estimates of turbulent mixing in geophysical settings typically depend on the efficiency at which shear-driven turbulence mixes density across isopycnals. To date, however, no unifying parameterization of diapycnal mixing efficiency exists due to the variability of natural flows and also due to certain ambiguities that arise from descriptions based on a single parameter. Here we highlight important ambiguities of some common single-parameter schemes in the context of a multiparameter framework that considers the independent effects of shear, buoyancy, and viscosity. Parameterizations based on the gradient Richardson number (Ri), the turbulent Froude number (FrT), and the buoyancy Reynolds number (Reb) are …

Coastal Defenses, U.S., Bert Chapman

Libraries Faculty and Staff Scholarship and Research

Provides an overview of U.S. military coastal defenses during the period up to and including the War 1812.

Determining Annoyance Thresholds Of Tones In Noise, Jennifer M. Francis, Joonhee Lee, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Building services equipment often produces noise signatures with significant tones in them that can lead to complaints in the built environment. Previous studies have investigated prominence levels of assorted tonal frequencies, but it is still unclear what prominence of the tones across varying tonal frequencies can lead to human annoyance. This project seeks to apply two different methods towards defining annoyance thresholds of tones in noise at two tonal frequencies: 125 Hz and 500 Hz. In the first, subjects are asked to perform a task, while exposed to ten minutes of a broadband noise spectrum with a specific level of …

Effects Of Tendon Spacing On In-Plane Behavior Of Posttensioned Masonry Walls, Dongun Ryu, Anil C. Wijeyewickrema, Mohamed A. Elgawady, M. A.K.M. Madurapperuma

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In-plane behavior of unbonded posttensioned clay brick masonry walls are investigated using detailed finite-element (FE) models. FE models of three walls having different aspect ratios of 1.50, 1.00, and 0.67 are developed. Effects of tendon spacing on in-plane behavior of these walls are investigated using different tendon spacings ranging from 0.61 m (2 ft) to 3.81 m (12.5 ft). In addition, the effects of having different horizontal reinforcement ratios of 0%, 0.1%, and 0.5% on the in-plane behavior of the walls were investigated. The stresses in the tendons are calculated using different approaches, and then the flexural strength of each …

A Unifying Framework For Parameterizing Stably Stratified Shear-Flow Turbulence, Benjamin D. Mater, Subhas Karan Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

An alternative framework for parameterizing stably stratified shear-flow turbulence is presented. Using dimensional analysis, four non-dimensional parameters of interest are identified that consider the independent effects of stratification, shear, viscosity, and scalar diffusivity. In the interest of geophysical applications, the problem is further simplified by considering only high Reynolds number flow. This leads to a two-dimensional parameter space based on a buoyancy strength parameter (i.e., an inverse Froude number) and a shear strength parameter. Consideration for the gradient Richardson number allows the space to be divided into an unforced regime, a shear dominated regime, and a buoyancy-dominated regime. On this …

A Comparative Study Of The Mechanical Properties, Fracture Behavior, Creep, And Shrinkage Of Chemically Based Self-Consolidating Concrete, Mahdi Arezoumandi, Mark Ezzell, Jeffery S. Volz

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study presents the results of an experimental investigation that compares the mechanical properties, fracture behavior, creep, and shrinkage of a chemically based self-consolidating concrete (SCC) mix with that of a corresponding conventional concrete (CC) mix. The CC and SCC mix designs followed conventional proportioning in terms of aggregate type and content, cement content, air content, water-cementitious materials (w/cm) ratio, and workability. Then, using only chemical admixtures, the authors converted the CC mix to an SCC mix with all of the necessary passing, filling, flowability, and stability requirements typically found in SCC. The high fluidity was achieved with a polycarboxylate-based …

An Experimental Investigation Of Crumb Rubber Concrete Confined By Fibre Reinforced Polymer Tubes, Osama Youssf, Mohamed Elgawady, Julie E. Mills, Xing Ma

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Due to the known loss of compressive strength experienced by crumb rubber concrete (CRC) compared with conventional concrete, there have been few applications explored to date for the structural use of these materials. This paper describes experimental work conducted to explore the possible future use of CRC for structural columns by evaluating the use of fiber reinforced polymer (FRP) confinement as a means of overcoming the material deficiencies (decreased compressive strength). The results indicated that the use of FRP to confine rubberized concrete effectively negates the decrease in strength and retains the advantages of increased ductility that arise from rubberized …