Architectural Engineering Commons^™

Binaural Room Impulse Response Database Acquired From A Variable Acoustics Classroom, Zhao Peng, Siu Kit Lau, Lily M. Wang, Sean Browne, Kenneth P. Roy

Durham School of Architectural Engineering and Construction: Faculty Publications

Room measurements were conducted in a variable acoustics classroom mockup space (epod) at Armstrong World Industries in Lancaster, Pennsylvania, USA. Binaural room impulse responses were measured in the epod using a head and torso simulator. Five reverberation time (RT) scenarios were achieved with various combinations of absorptive wall panels and acoustical ceiling tile. These provided a range of mid-frequency RTs from 0.4 to 1.1 seconds. Three of the five RT scenarios were achieved using two different material configurations to also consider material location effects. For each of the eight material configurations, two student-teacher orientations were tested. One orientation had all …

Effects Of Reverberation And Noise On Speech Comprehension By Native And Non-Native English-Speaking Listeners, Z. Ellen Peng, Lily M. Wang, Siu-Kit Lau, Adam M. Steinbach

Durham School of Architectural Engineering and Construction: Faculty Publications

Previous studies have demonstrated the negative impact of adverse signal-to-noise-ratios on non-native English-speaking listeners' performance on speech recognition using recall tasks, as well as implied that comprehension skills were more impaired than recognition skills under reverberation and noise. The authors have themselves previously conducted a pilot study on three native and three non-native Englishspeaking listeners to examine the effects of reverberation and noise using speech comprehension tasks. Those results suggested that speech comprehension performance is worse under longer reverberation times (RT), and that a longer RT is more detrimental to speech comprehension by non-native listeners than native listeners. This paper …

Acoustic Tweets And Blogs: Using Social Media In An Undergraduate Acoustics Course, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Each fall, the author teaches an undergraduate architectural acoustics course to around 40 third-year architectural engineering students at the University of Nebraska. Beginning in 2011, a social media component was introduced to explore the use of this technology and how it may supplement the students' learning experience. Students were given an opportunity to receive extra credit by using Twitter and/or blogging about course material using a set hashtag (#AE3300) or through the course website. Results were positive, and the author will discuss pros and cons that she has experienced in adding this social media component. Suggestions for future implementations and …

Elec 2110: Elements Of Electrical Engineering—A Peer Review Of Teaching Project Benchmark Portfolio, Mahmoud Alahmad

UNL Faculty Course Portfolios

I have been teaching this class for the last five years. As an introductory course to electrical engineering, there is a lot of material that needs to be covered. All the material is important and relevant, and I try to go in-depth in each topic area. This approach has resulted in overwhelming the students and made them struggle with the course content, application and utilization. As I consider this course for the peer review, I am evaluating the depth of each topic and the opportunity to adjust the approach and method used to introduce new concepts and at the same …

Lifecycle Energy Consumption Prediction Of Residential Buildings By Incorporating Longitudinal Uncertainties, Endong Wang, Zhigang Shen

Durham School of Architectural Engineering and Construction: Faculty Publications

Accurate prediction of buildings’ lifecycle energy consumption is a critical part in lifecycle assessment of residential buildings. Longitudinal variations in building conditions, weather conditions and building’s service life can cause significant deviation of the prediction from the real lifecycle energy consumption. The objective is to improve the accuracy of lifecycle energy consumption prediction by properly modelling the longitudinal variations in residential energy consumption model using Markov chain based stochastic approach. A stochastic Markov model considering longitudinal uncertainties in building condition, degree days, and service life is developed: 1) Building’s service life is estimated through Markov deterioration curve derived from actual …

Investigating Self-Cooling Effects Of Ventilated Attics Under Different Roof And Ambient Temperatures In Summer, Zhigang Shen, Shimin Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

An unsteady computational fluid dynamics model is employed to simulate summer-time buoyancy-driven turbulent ventilation in gable-roof attics of residential buildings. The energy performance of vented attics is assessed by comparing their performance to sealed attics with the same geometry and insulation configurations. The simulated boundary conditions of the roof-top temperature ranging between 295.15 K and 345.15 K, coupled with an ambient temperature ranging between 295.15 K and 315.15 K, resemble the summer attic conditions with effects of solar irradiance on the roofs. Simulation results indicate that both the vented and sealed attics are dominated by thermal stratification. The cooling load …

An Innovative Solution Set Of Algorithm For Converting Architectural Drawings To Vector-Based Computer Graphics, Yuye Peng

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

Appraisal Floor Plan Sketch (AFPS) as a simplified architectural floor plan shows the bird's eye view of a building’s spatial arrangement. An efficient automated vectorization system of AFPS not only fulfills AFPS’s preservation and dissemination purposes but also helps extract the building’s geometric information, which can be used to create 3D models of the building and improve building energy efficiency. The purpose of this study is to develop an automated system for converting scanned AFPS into vector based computer graphics.

Text/graphic separation and corner detection are two essential components in this vectorization system. Text/graphic separation ensures that only graphic data …

Effects Of Acoustic Environments On Speech Comprehension By Native-English-Speaking Listeners, Zhao Peng, Lily M. Wang, Siu Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

This study investigates the effects of acoustic conditions on speech comprehension, rather than speech intelligibility as often reported in existing literature. Sets of 15-minute-long listening comprehension tests were developed based on the format of the Test of English for International Communication (TOEIC). Each test set includes four types of tasks: matching aural phrases to photographs, selecting appropriate responses to aural questions, and answering questions after listening to conversations (between two talkers) and talks (single talker). Within the Nebraska acoustics test chamber, native-English-speaking participants are asked to perform these tests under 15 acoustic conditions, from combinations of three background noise levels …

Effects Of Short Noise Bursts On Human Performance And Perception, Christopher Ainley

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

The goal of this research project is to better quantify human reactions to short bursts of noise, to complement research at NASA Langley Research Center on evaluating human response inside buildings to low-level sonic booms. The project involved exposing participants over 30-minute sessions to a number of 250 ms broadband noise bursts of certain levels, presented in a controlled yet randomized fashion throughout the session, and gathering responses on human perception and performance on an arithmetic task dealing with short-term memory. While previous research has demonstrated effects of noise bursts of varying amplitudes on other types of tasks that study …

Residential Energy Recovery Radiant Heat System, Scott Sharp

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

Energy recovery systems aim to recover waste energy that is normally lost to the environment. Waste energy comes in a variety of forms. Many processes involving building HVAC involves transferring energy from one working fluid to another. Governing codes put strict requirements on ventilation requirements for various occupancy types. Increased ventilation demands more from the HVAC equipment since outdoor air (ventilation air) is being brought into the building and requires tempering in order to retain occupant comfort. The energy required to temper this air increases as ventilation rates increase. Many commercial buildings have implemented exhaust air energy recovery, or runaround …

Electromagnetic Harvesting To Power Energy Management Sensors In The Built Environment, Evans Sordiashie

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

Recently, a growing body of scholarly work in the field of energy conservation is focusing on the implementation of energy management sensors in the power distribution system. Since most of these sensors are either battery operated or hardwired to the existing power distribution system, their use comes with major drawbacks. Battery maintenance and associated labor costs can make implementing sensors very expensive. Although hardwired sensors require very little post-installation maintenance, any energy savings they may procure is offset by the amount of energy expended during the course of the sensors normal operation. In response to these energy challenges, this thesis …

Damage Detection In Metamorphic Stone Blocks Utilizing Impact-Echo Testing And Modal Analysis, Alexander C. Jording

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

Existing buildings decay with the passage of time, and as a result, continually require maintenance or rehabilitation. When considering existing structures, testing is often necessary to complete structural analysis in preparation for rehabilitation or repair. Non-destructive testing provides a structural assessment method applicable to a variety of materials and structures. The hypothesis of this research is that impact-echo testing, one of the many NDT techniques, can be adopted to develop a reliable and standardized method to assess the condition of rectangular metamorphic stones. After the baseline material parameters and general response to impact-echo testing were established, a novel method to …

A Composite Structural Steel And Prestressed Concrete Beam For Building Floor Systems, Nathan Dewit

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

Precast prestressed concrete beams, such as rectangular and inverted tee beam, currently used in residential and commercial buildings are deep, heavy, and limited to span-to-depth ratios of 15. The research proposes a composite structural steel and prestressed concrete beam that is shallow, light, easy to produce and erect, and able to achieve a span-to-depth ratio of 24. The proposed beam is designed to be used with precast columns, hollow-core planks, and a cast-in-place topping to create a moment-resisting floor system that minimizes the need for shear walls. The goal of this system is to eliminate as many of the limitations …

A Comparative Study Of Three Feedback Devices For Residential Real-Time Energy Monitoring, Mahmoud Alahmad, Patrick G. Wheeler, Joshua Eiden, Adam Brumbaugh

Durham School of Architectural Engineering and Construction: Faculty Publications

Residential energy consumption accounts for 21% of the total electricity use in the United States. Unfortunately, research indicates that almost 41% of this power is wasted. Changing the way that consumers use energy may be important in reducing home energy consumption. This paper looks at whether the implementation of certain real-time energy monitors has an impact on the residential rate of energy consumption in a metropolitan area with relatively low electricity rates. In the following case study, 151 Omaha residences were equipped with two variants of the Aztech In-Home Display (Aztech) as well as the Blue Line Power Cost Monitor …

A Numerical Investigation Of Two Phase Solar-Collector Pipe, Seyyed Hashem Abedini

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

In the United States, major portions of the annual electrical and primary energy are consumed for buildings. To help reduce the energy consumption of non-renewable energy sources, this study investigates a new technology for harvesting solar energy using a boiling-condensing cycle with water in a solar collector. The fluid circulation is under natural forced convection. A solar collector is made of a black lacquer copper with 2 meters in length is used. The design of the system is presented to simulate heat transfer rate in a cold climate an average daily solar irradiation of 4.5kWh/m²/day, e.g. for Omaha …

The Assessment Of High Dynamic Range Luminance Measurements With Led Lighting, Yulia I. Tyukhova

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

This research investigates whether a High Dynamic Range Imaging (HDRI) technique can accurately capture luminance values of a single LED chip. Previous studies show that a digital camera with exposure capability can be used as a luminance mapping tool in a wide range of luminance values with an accuracy of 10%. Previous work has also demonstrated the ability of HDRI to capture a rapidly-changing lighting environment with the sun. However these publications don’t investigate HDRI’s ability to capture a bright light source with a narrow light distribution (LED lighting).

Some of the existing concerns in LED technology today include low …

A Directionally Tunable But Frequency-Invariant Beamformer On An Acoustic Velocity-Sensor Triad To Enhance Speech Perception, Yue Ivan Wu, Kainam Thomas Wong, Xin Yuan, Siu-Kit Lau, Shiu-Keung Tang

Durham School of Architectural Engineering and Construction: Faculty Publications

Herein investigated are computationally simple microphone-array beamformers that are independent of the frequency-spectra of all signals, all interference, and all noises. These beamformers allow the listener to tune the desired azimuth-elevation “look direction.” No prior information is needed of the interference. These beamformers deploy a physically compact triad of three collocated but orthogonally oriented velocity sensors. These proposed schemes’ efficacy is verified by a jury test, using simulated data constructed with Mandarin Chinese (a.k.a. Putonghua) speech samples. For example, a desired speech signal, originally at a very adverse signal-to-interference-and-noise power ratio (SINR) of -30 dB, may be processed to become …

Application Of Drum-Buffer-Rope Methodology In Scheduling Of Healthcare System, Arefeh Mohammadi, Emmanuel S. Eneyo

Durham School of Architectural Engineering and Construction: Faculty Publications

Theory of constraints (TOC) is a management philosophy that seeks to increase throughput (efficiency or performance) of the system by identifying those processes that are constraining the system bottlenecks. There have been very few profound studies of TOC in health care systems. In order to fill this gap, this study was conducted to determine how healthcare systems are utilizing components of TOC to schedule operations and what results are being obtained. This is done by using a patient flow model for a radiotherapy section of a hospital. The drum-buffer-rope (DBR) was used as the methodology for scheduling this flow. Successful …

Teaching Sustainable Design Using Bim And Project-Based Energy Simulations, Zhigang Shen, Wayne Jensen, Tim Wentz, Bruce Fischer

Durham School of Architectural Engineering and Construction: Faculty Publications

The cross-disciplinary nature of energy-efficient building design has created many challenges for architecture, engineering and construction instructors. One of the technical challenges in teaching sustainable building design is enabling students to quantitatively understand how different building designs affect a building’s energy performance. Concept based instructional methods fall short in evaluating the impact of different design choices on a buildings’ energy consumption. Building Information Modeling (BIM) with energy performance software provides a feasible tool to evaluate building design parameters. One notable advantage of this tool is its ability to couple 3D visualization of the structure with energy performance analysis without requiring …

An Adaptive Utility Interactive Photovoltaic System Based On A Flexible Switch Matrix To Optimize Performance In Real-Time, Mahmoud Alahmad, Mohamed Amer Chaaban, Siu Kit Lau, Jonathan Shi, Jill Neal

Durham School of Architectural Engineering and Construction: Faculty Publications

Reconfigurable architectures are of great interest to system designers to improve the system’s operation and efficiency. In this paper, we propose an adaptive utility interactive photovoltaic (PV) system based on a novel Flexible Switch array Matrix topology. This proposed system maximizes the generated power in real-time in response to operational conditions such as shading, soiling, mismatches, and module failure among others. The proposed system is a compromise in the utilization of power conditioning equipment to maximize energy capture and system efficiency. Simulation results demonstrate an average 13% improvement in efficiency when compared with the central inverter topology performance. A prototype …

Effects Of Roof Pitch On Air Flow And Heating Load Of Sealed And Vented Attics For Gable-Roof Residential Buildings, Shimin Wang, Zhigang Shen

Durham School of Architectural Engineering and Construction: Faculty Publications

Pitch value is an important consideration in residential gable roof design and construction. However, how roof pitch, coupled with air flows in attic space, affects the energy performance of building attics has been barely investigated. In this paper, a 2D unsteady computational fluid dynamics (CFD) model is employed to investigate the effects of roof pitch on air flow and heating load of both sealed and vented attics for gable-roof residential buildings. The simulation results show that air flow in the sealed attics is steady and asymmetric, while that in the vented attics is a combination of an essentially symmetric base …

Effects Of Inclusion Shapes Within Rigid Porous Materials On Acoustic Performance, Hyun Hong, Siu-Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

The present study investigates the influence of various shapes of inclusions having same volume embedded in a porous rigid material. Previous studies showed improvement of the broadband sound absorption with particular shapes of inclusions. However, different volumes of the inclusions have been considered; therefore, the bulk densities are not the same for comparison. The present study extends the investigations of inclusions in porous materials with same volume (or bulk density) to eliminate the influence by the change of bulk density. The effects of shape will be discussed. Finite element modeling will be used for this study. Total four different shapes: …

Impacts Of Ventilation Ratio And Vent Balance On Cooling Load And Air Flow Of Naturally Ventilated Attics, Shimin Wang, Zhigang Shen

Durham School of Architectural Engineering and Construction: Faculty Publications

The impacts of ventilation ratio and vent balance on cooling load and air flow of naturally ventilated attics are studied in this paper using an unsteady computational fluid dynamics (CFD) model. Buoyancy-driven turbulent ventilations in attics of gable-roof residential buildings are simulated for typical summer conditions. Ventilation ratios from 1/400 to 1/25 combined with both balanced and unbalanced vent configurations are investigated. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively insensitive to the variations in ventilation ratio and vent configuration. The predicted temperature fields are characterized …

The Impact Of Roof Pitch And Ceiling Insulation On Cooling Load Of Naturally-Ventilated Attics, Shimin Wang, Zhigang Shen, Linxia Gu

Durham School of Architectural Engineering and Construction: Faculty Publications

A 2D unsteady computational fluid dynamics (CFD) model is employed to simulate buoyancy-driven turbulent ventilation in attics with different pitch values and ceiling insulation levels under summer conditions. The impacts of roof pitch and ceiling insulation on the cooling load of gable-roof residential buildings are investigated based on the simulation of turbulent air flow and natural convection heat transfer in attic spaces with roof pitches from 3/12 to 18/12 combined with ceiling insulation levels from R-1.2 to R-40. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively …

Development And Evaluation Of A Simplified Modeling Approach For Hydraulic Systems, Yuebin Yu, Vivian Loftness, Daihong Yu, Yan Lu, Volker Hartkopf

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper presents how a hydraulic system can be properly modeled for hydraulic balancing, knowledge of flow distribution, coupled simulation, and evaluation of control, etc. It focuses on water-based heating and cooling systems, which generally have high energy efficiency in design but could perform poorly in reality due to the undersensing condition and strong thermal-hydraulic coupling. The study introduces the motivation, presents the simplified modeling methodology, and illustrates the model and simulating structure. A preliminary evaluation of the method is conducted with two simple simulations. The proposed “node-branch-state” modeling approach could be easily modified, expanded and integrated into a detailed …

Ann Based Load Identification And Forecasting System For The Built Environment, Hosen Hasna

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

"Phantom Loads" cause energy waste in homes and the built environment as a whole. Consumers spend more than $3 billion a year on "Phantom Load" in the United States alone. The goal of this work is to conserve energy by increasing consumer awareness on their energy usage and appropriate tools which in turn will be reducing and /or eliminating phantom loads and mismanagement of the load in the built environment. A further goal is to improve upon existing power distribution systems in the built environment with limited hardware additions to increase energy conservation. This work investigates remote identification of load …

Technologies Enabling Sustainability In The Built Environment, Mahmoud Alahmad, Muhammad Zulfiqar, Hosen Hasna Hh, Timothy Wisnieski, Nasser Aljuhaishi, Hamid Sharif

Durham School of Architectural Engineering and Construction: Faculty Publications

Energy conservation is among society’s greatest challenges, and the built environment has a concentrated impact on our natural environment, economy, and health. Fundamental understandings of how energy is consumed, monitored, and controlled are key prerequisites for an energy conservation process. This paper evaluates the effectiveness of real-time energy monitors (RTM) to influence behavior change in residential consumers. A methodology for remote identification of load types along the electrical circuitry where they (load) are being consumed is also presented. The load type and status (on, off, standby) are determined both remotely and in a non-intrusive manner using Non-Intrusive Load Monitoring Methods. …

Implementation Of Integrated Commissioning, Retrofits, And Control Optimization Process In A Small Commercial Building, Xiangnan Shi

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

A large amount of the primary energy consumed in the US is derived from the built environment followed by energy consumed in the transportation and industrial sectors. Consequently, improving the energy efficiency of buildings is an important part of ensuring a more sustainable world for future generations. Of the various techniques employed to improve the energy efficiency of buildings, commissioning and retrofits continue to be the most widely applied solutions. Control optimization, mainly imbedded with continuous commissioning so far, is not applied as widely. Even though there are currently a few applications that integrate all three techniques, no comparison has …

Optimized Control Strategies For A Typical Water Loop Heat Pump System, Xu Lian

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

Water Loop Heat Pump (WLHP) System has been widely utilized in the Heating, Ventilating and Air Conditioning (HVAC) industry for several decades. There is no doubt about the energy saving potential of this type of system from the design and construction perspective. However, there are still many unsolved problems, such as high loop pump energy consumption, low heat pump efficiency and high electricity cost due to improper operation, although the system design intension was to save energy. Thus, how to control the WSHP to realize its energy-efficient value is an innovative but practical topic on which this thesis will focus. …

A Virtual Supply Airflow Rate Meter In Rooftop Air Conditioning Units, Daihong Yu

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

Virtual sensing technology aims to estimate difficult to measure, expensive, or new quantities by using multifarious mathematical models along with non-invasive and low-cost measurements. Such embedded intelligence is a key to improving the performance of building systems in terms of functionality, safety, energy efficiency, environmental impacts, and costs. Considering the progress that has been achieved over many various fields (e.g., process controls, automobiles, avionics, autonomous robots, telemedicine) within the last two decades, numerous intelligent features have been incorporated and enabled that would otherwise not be possible or economical.

To identify the potential opportunities and research/development needs of virtual sensing technology …