Architecture Commons^™

Spatial Release From Masking In Anechoic And Reverberant Environments, Drake Andrew Hintz

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Listening with both ears provides children with access to binaural and monaural cues that are helpful for understanding speech in competing babbles. Specifically, when the target and masker are spatially separated, children can gain an intelligibility benefit which is known as spatial release from masking (SRM). Recent work [Peng et al., 2021 JASA] suggested that school-age children demonstrated immature SRM using binaural cues that are distorted by reverberation. In this follow-up study, we further investigate the effect of reverberant distortion on individual auditory spatial cues, namely binaural and monaural head shadow cues. We compare SRM between adults and school-age children …

Continuous Time Recurrent Network For Human Activity Detection, Abdallah Al Zubi

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Human activity detection is crucial to personalize the control of the building environment. For example, understanding certain human activities (e.g., walking, sitting, etc.) for an occupant in a building helps provide the proper thermal comfort control. However, these applications require large-scale neural networks that are challenging to implement and train.

In this thesis, we implemented a continuous-time recurrent neural network implementation (CTRNN) network that can solve real-time human activity detection with a smaller-size network. The CTRNN uses differential equations with a time constant to describe the neuron equations. It was implemented and trained for the first time using TensorFlow. Specifically, …

Framework Development For Evaluating The Impacts Of Nursing Home Acoustics On Older Adults, Brian J. Puckett

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Nursing homes are complex, multi-faceted environments which provide necessary medical supervision and housing for older adults in need of long-term care. With cognitive and sensory impairments being common adversities faced throughout the aging process, research is needed to better understand characteristics of the built environment which may contribute to difficulties for nursing home residents. Noise, in particular, has been shown to be problematic for nursing home residents in a variety of ways including disrupting sleep, associating with behavioral and psychological symptoms of dementia, and leading to increased readmission to hospitals due to verbal communication misunderstandings. As the older adult population …

Data-Driven Framework For Predicting And Scheduling Household Charging Of Evs, Ahmad Almaghrebi

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

The increasing prevalence of EV charging poses challenges for power grid stability and quality due to high charging load demands. Without effective energy management strategies for EV charging, the simultaneous power demand from numerous EVs can strain the electric grid, impacting power quality and the wholesale electricity market. To address these challenges, this dissertation presents a comprehensive framework comprising five critical tasks: analyzing EV charging behavior, optimizing charging schedules, developing predictive models, analyzing aggregated impacts, and evaluating implications of predicted user behavior on scheduling. By examining EV charging behavior at household and public charging stations, this study aims to understand …

Signal Classification Based On Analog Computing Using Mems Network, Mohammad Okour

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

The rising complexity of machine learning algorithms and Artificial Intelligence in many applications, such as smart building, has prompted the development of alternate computing options. Because of their compact size, low power consumption, and diverse functionality, microelectromechanical systems (MEMS) have emerged as a possible candidate. This thesis focuses on using MEMS networks as computing units to classify a simple signal classification task using neural network methodology. The study intends to show the potential of using MEMS as an analog computing unit by discussing the advantage of the bi-stability pull-in behavior and hysteresis to create an accurate classifier of these waveforms. …

Airborne Infection Risks From Covid-19 In Meat Processing Plants And Different Solutions To Mitigate The Risks, Debayan Shom

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Meat processing plants are linked to the rapid spread of COVID-19 cases. A related literature review shows a lack of proper ventilation standards for the meat processing plants for workers’ health and safety. Ventilation rates in these plants are considered adequate if the meat products are unadulterated. Thus, the air distribution and ventilation rate experiments were conducted in three meat processing plants. These measured ventilation rates were either compared to ASHRAE Std. 62.1 (2019) for a similar space or the design values provided by the plant’s administration. The measured values were low in common spaces, such as the cafeteria and …

Investigation Of The Prevalence Of Faults In The Heating, Ventilation, And Air-Conditioning Systems Of Commercial Buildings, Amir Ebrahimifakhar

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

This dissertation describes a large-scale investigation of heating, ventilation, and air-conditioning (HVAC) fault prevalence in commercial buildings in the United States. A multi-year dataset with 36,556 pieces of HVAC equipment including air handling units (AHUs), air terminal units (ATUs), and packaged rooftop units (RTUs) was analyzed to determine values for several HVAC fault prevalence metrics. The primary source of data for this study comes from three commercial fault detection and diagnostics (FDD) providers. Since each FDD provider uses different terms to refer to the same fault in an HVAC system, a mapping function was created for each FDD provider’s dataset, …

Out-Of-Plane Behavior Of Concrete Insulated Wall Panels With 2-Inch, 8-Inch, And 10-Inch Insulation, Jacob Luebke

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Insulated concrete sandwich wall panels provide structurally and thermally efficient building envelopes and are becoming more popular as energy regulations tighten. To continually adapt to an ever-changing building market and new energy regulations, insulated concrete wall panels are being constructed with thinner wythes, thicker insulation, and relying on partial composite action to decrease material costs and increase thermal and structural efficiency. Numerous methods of the design of partially composite insulated concrete sandwich wall panels have been introduced in recent decades and have been verified by comparing their results to existing experimental testing. Existing testing data for insulated concrete sandwich wall …

Studying Acoustical Characteristics Of Occupied Restaurants, Jared Paine

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Sound level data and occupancy data have been logged in five restaurants by the research team at the University of Nebraska – Lincoln. Sound levels and occupancy at 10 second intervals were documented over time periods of roughly two hours during active business hours. Noise levels were logged with dosimeters distributed throughout each restaurant, and occupancy was obtained from images recorded by infrared cameras. This work presents data on average sound levels and statistical metrics, such as L10 and L90 values as well as on each restaurant’s Acoustical Capacity and Quality of Verbal Communication, as introduced by Rindel (2012). Acoustical …

Facilitating The Industrial Sector's Adoption Of Collaborative Project Delivery Methods, Xavier Wood-Aliberch

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

In an effort to improve outcomes in the civil and healthcare sectors, clients have adopted collaborative project delivery methods for the delivery of their capital projects. The success stories in these sectors have gathered the attention of clients in the industrial sector, where cost and schedule overruns have become the norm. The central objective of this thesis is to help clients make the transition to this new type of project delivery.

This thesis was written in a three-paper format, where each paper addresses a challenge with the adoption of collaborative delivery methods. The first paper investigates what type of industrial …

Led Zip Model Development, Mhd Anas Alkrch

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

The representation of load components deemed to be an essential factor for power system studies as the load characteristics influence the system performance. Thus, choosing an appropriate load model for load behavior studies is very significant for system analysis purposes. Load models can be categorized into three types: static, dynamic, and composite models. Static ZIP load model is a well-known model in the power industry, it represents the relationship between the active and reactive power as a function of the applied voltage. In this paper, a detailed review of the existing static ZIP model coefficients for load components achieved by …

A Comparison Between Ultrasonic Guided Wave Leakage And Half-Cell Potential Methods In Detection Of Corrosion In Reinforced Concrete Structures, Ahmad Shoaib Amiri

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Corrosion of reinforcing steel bars (rebar) in reinforced concrete decks can lead to serious structural issues in bridges. Ultrasonic Testing (UT) methods provide small wavelengths that can be used for early detection of several types of deterioration. The recently-developed Ultrasonic Guided Wave Leakage (UGWL) Method utilizes steel as the waveguide and measures the energy leaked into the surrounding concrete. Previous studies completed at University of Nebraska-Lincoln demonstrated that the measurements of the leaked energy using receivers from the concrete surface can successfully identify early stages of various flaws such as corrosion, delamination, and cracking. In this method, the longitudinal waves …

Understanding The Impact Of Room Acoustic Conditions On The Kurtosis Levels Of Various Noise Signals, William Spallino

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Impulsive noise can be common in certain occupational and recreational settings, such as manufacturing plants, construction sites, and firing ranges. While many regulations and guidelines for noise exposure exist, their mathematical basis is stronger for continuous noise, and concerns have been raised about the possibility that impulsive noise may be more harmful to people’s hearing than those metrics would let on. Much work has been done on establishing metrics that accurately assess the severity and hearing risk associated with impulsive noise, but the effects of room acoustic conditions on those metrics have been heretofore understudied.

This study calculated room impulse …

Evaluation Of The Dynamic Behavior Of Steel Staircases With Concrete Filled Pan Treads, Tyler Sondag

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Vibration serviceability of staircases has been a growing challenge for structural engineers due to changing materials and structural forms. In order to prevent or correct serviceability problems due to structural vibrations, structural engineers should be able to predict the dynamic performance of a staircase structure. However, there are few technical guides available for designing steel staircases, and the ones that do exist are often limited in their applications. Currently, there is a lack of research on staircases that are less prone to vibrations, such as staircases with concrete filled pans that are composed of face and wall stringers. Therefore, the …

The Impact Of Pev User Charging Behavior In Building Public Charging Infrastructure, Ahmad Almaghrebi

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Plug-in electric vehicles (PEVs) play a significant role in the development of green cities since they generate less pollution than conventional vehicles. To promote PEV adoption and mitigate range anxiety, charging infrastructure should be deployed at strategic locations that are readily accessible to the public. Nebraska is working on the expansion of charging infrastructure around the state; however, stakeholders face several difficulties in trying to minimize irregular charging behaviors. Most electric vehicle users plug in and leave their vehicles for an extended time at public parking lots designated for PEVs. Some users even leave their vehicles for longer than 24 …

An Investigation Of The Operational And Design Characteristics Of Circadian Lighting Systems, Aaron Adams

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

This report investigates the operation of circadian lighting systems to gain an understanding of the main design and control characteristics and to promote different objectives for use. Research is guided by asking how color intensity, color temperature and their temporal characteristics are related to the circadian response, and how this knowledge can be utilized when designing and operating lighting systems for indoor environments. This report consists of an extensive literature review and case study application cut short by the impact of the novel coronavirus. The case study takes place in an office space housed on the UNMC campus featuring an …

Explorations Of Acoustic Trends In Data Logged In K-12 Classrooms, Kieren Smith

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

The classroom environment influences the ability of children to learn. To ascertain the effect of indoor environment parameters on student achievement, a large-scale project was launched, collecting time-logged data from 220 k-12 classrooms in the eastern Nebraska region for six days each. Data were collected from a variety of disciplines, including acoustics, lighting, indoor air quality, and thermal comfort. This thesis focuses on the acoustic parameters, looking first at how overall classroom values--including average sound levels and room reverberation time--influence student achievement. Using structural equation modeling, the average sound level during times with speech present was discovered to have a …

Data Driven Approach To Thermal Comfort Model Design, Mostafa Rafaiejokandan

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Apart from the dominant environmental factors such as relative humidity, radiant, and ambient temperatures, studies have confirmed that thermal comfort significantly depends on internal personal parameters such as metabolic rate, age, and health status. This study reviews the sensitivity of the Predicted Mean Vote (PMV) thermal comfort model relative to its environmental and personal parameters of a group of people in a space. PMV model equations adapted in ASHRAE Standard 55–Thermal Environmental Conditions for Human Occupancy, are used in this investigation to conduct a parametric study by generating and analyzing multi-dimensional comfort zone plots. It has been found that personal …

Evaluation Of Hospital Soundscapes To Improve Patient And Staff Experience, Jay Bliefnick

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Hospital soundscapes can be difficult environments to assess acoustically due to the continuous activity within units. Routinely, patients perceive these soundscapes poorly when rating their hospital experience on HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) surveys administered after discharge. In addition, hospital staff can be negatively impacted by the acoustical environments in which they work, affecting both performance and job satisfaction. This doctoral research addressed these issues across three phases by collecting acoustical measurements within three individual hospitals, comparing results with provided patient and staff survey information, and conducting laboratory tests of hospital noise perception. In the first …

A Case Study On The Design Of Safe Spaces In Hospitals Vulnerable To Tornadoes In Central Us, Lucy Owusua Ampaw - Asiedu

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

In the wake of recent disasters happening around the world such as the earthquake in Italy (January 2017); hurricanes in the United States (U.S.) (September 2016 and 2017); and compounding disasters in Haiti (September 2010 and 2016); to our best knowledge, never has the world seen the need to work on preemptive rather than reactionary measures to address this issue. Tornadoes are natural hazards that commonly occur in mid-western and central states of the U.S. Tornadoes, like all natural hazards, are very destructive and result in massive destruction to building structures, causing billions of dollars in damage and claim many …

Effects Of Reverberation Conditions And Physical Versus Virtual Source Placement On Localization In Virtual Sound Environments, Anna Catton

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Sound field synthesis systems vary in number and arrangement of loudspeakers and methods used to generate virtual sound environments to study human hearing perception. While previous work has evaluated the accuracy with which these systems physically reproduce room acoustic conditions, less is known on assessing subjective perception of those conditions, such as how well such systems preserve source localization. This work quantifies the accuracy and precision of perceived localization from a multi-channel sound field synthesis system at Boys Town National Research Hospital, which used 24 physical loudspeakers and vector-based amplitude panning to generate sound fields. Short bursts of broadband speech-shaped …

Harmonics Elimination In Three Phase Cascade H-Bridge Multilevel Inverter Using Virtual Stage Pwm, Amro Quedan

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

The multilevel inverters are one of the great solutions that are proposed to satisfy the demand for high-power application and the significant integration of renewable energy. The conversion process from DC to AC must be done at high efficiency to decrease the energy loss and to ensure the electric grid power quality. The Total Harmonic Distortion (THD) is the most important feature that indicates the efficiency of the conversion process. In this research, due to the advantages of the cascade H-bridge inverter over other topologies, it has been used with the virtual stage PWM technique to investigate two different methods …

Perception Of Spatial Impression Due To Varying Positions Of The Source On Stage, Sungbeen Cho

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

The listener’s surrounding environment affects the perception of sound. The environment includes physical factors such as space size, shape, and finish materials, and psychological factors such as individual difference of impression, and vision. Acoustic spatial impression can be defined as the concept of the type and size of space at which a listener arrives spontaneously when he/she is exposed to an appropriate sound field. This thesis analyzes how physical factors in enclosed spaces affect the acoustic spatial impression, and how sound sources at different positions on stage are perceived in different shapes of spaces.

First, existing spatial impression parameters, IACC …

An Investigation Of Dx Cooling Coil Inherent Characteristics, Krittima Santiwattana

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

DX cooling coil (DCC) systems have dominated light commercial and household applications in the U.S for several decades. Approximately 14.5% of energy use is consumed by space cooling in commercial buildings, whereas 87% of households are installed with air-conditioners. Improper installation, poor design, and lack of optimized control/operations incur faults in HVAC systems causing 25% to 50% energy waste in a building. These consequences are subject to inefficient equipment modelling of which is developed from: (1) insufficient understanding in equipment characteristics, (2) uncertainties in testing environment and data, and (3) access and cost limitations. Therefore, in this thesis DCC inherent …

A Generic Benchmark For A Mini-Split Heat Pump System, Yuchen Wang

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Heating, Ventilation, and Air Conditioning (HVAC) accounts for half of the building energy consumption in the U.S where Mini-Split Heat Pumps (MSHPs) are an emerging type of HVAC system. Their utilization has greatly increased by 34% from 2009 to 2013 and high potential EER is recognized for MSHPs. However, there is limited research involving MSHPs systems, and there is no generic benchmark for system testing and modeling. The available simulation tools such as VapCyc, GreatLab, and CYCLE_D are either too complicated, difficult to access, or not freely available. Therefore, an accurate and public share generic benchmark is essential and will …

How Acoustics In California High Performance Schools Relate To Student Achievement, Devin K. Wong

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

This research project seeks to determine if students attending K-12 schools meeting a minimum standard of high performance classroom conditions in the state of California do evidence higher scholastic achievement, based on publically available results on state-wide standardized tests. In three phases, a subset of 200+ schools applying for grants dedicated to building high performance schools over the past decade was correlated with an existing database of achievement scores for all public schools in California. The criteria utilized to specify high performance classrooms was provided by the California High Performance Initiative (HPI) Grant program. Academic achievement was evaluated on a …

Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

One of the most common problems in noise control is the attenuation of low frequency noise. Typical solutions require barriers with high density and/or thickness. Membrane-type acoustic metamaterials are a novel type of engineered material capable of high low-frequency transmission loss despite their small thickness and light weight. These materials are ideally suited to applications with strict size and weight limitations such as aircraft, automobiles, and buildings. The transmission loss profile can be manipulated by changing the micro-level substructure, stacking multiple unit cells, or by creating multi-celled arrays. To date, analysis has focused primarily on experimental studies in plane-wave tubes …

The Effects Of Tones In Noise On Human Annoyance And Performance, Joonhee Lee

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Building mechanical equipment often generates prominent tones because most systems include rotating parts like fans and pumps. These tonal noises can cause unpleasant user experiences in spaces and, in turn, lead to increased complaints by building occupants. Currently, architectural engineers can apply the noise criteria guidelines in standards or publications to achieve acceptable noise conditions for assorted types of spaces. However, these criteria do not apply well if the noise contains perceptible tones. The annoyance thresholds experienced by the general population with regards to the degree of tones in noise is a significant piece of knowledge that has not been …

Quantification Of Time Varying Directivity Of Musical Instruments, Madeline A. Davidson

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Static directivity patterns of musical instruments have been mapped somewhat extensively, but little research has been done in analyzing the directivity patterns of musical instruments over time as they play. Directivity patterns can be affected by variables such as instrument, frequency, dynamics, and style. This thesis proposes a set of quantification methods of time varying directivity, all derived from the maximum Directivity Index analyzed at consecutive short-duration time windows comprising the musical excerpt. The instrumental recordings used in this paper are taken in an anechoic chamber using either a 5, 13, or 32 multichannel setup. From the values of maximum …

Subjective Perception Of Varying Reflection Densities In Room Impulse Responses, Hyun Hong

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Reverberation time (RT) is a metric commonly used to describe room acoustic conditions, but different rooms which have the same reverberation time can have different reflection densities. Much less is known about how humans perceive different reflection densities and how sensitive humans are to changes in reflection density. Previous investigations in the existing literature have studied the upper limit of distinguishable reflection density using artificial impulse responses, but not with more realistic impulse responses simulated in room acoustic software or measured from real rooms. The aim of this dissertation is to investigate methods for quantifying reflection density from measured impulse …