Architecture Commons^™

An Adaptive Photovoltaic-Inverter Topology, Mahmoud Alahmad, Mohamed Amer Chaaban, Siu Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

A new inverter topology for Adaptive photovoltaic (PV) system is proposed. An improvement in the power generation of the system during different operating conditions is achieved. The proposed configuration provides flexible connection between the PV modules and the inverters to meet current conditions of PV array. Preliminary simulation results are provided for an adaptive PV array. Efficiency comparison between traditional PV system configurations is discussed. Potential improvement using the proposed adaptive configuration is sited.

Non-Intrusive Electrical Load Monitoring And Profiling Methods For Applications In Energy Management Systems, Mahmoud Alahmad, Hosen Hasna Hh, Evans Sordiashie

Durham School of Architectural Engineering and Construction: Faculty Publications

"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 paper is to conserve energy by increasing consumer awareness on their energy usage and reducing and /or eliminating phantom loads 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 paper investigates remote identification of load types and the locations along the electrical circuitry where they (load) are …

A Novel Photovoltaic/Battery Structure For Solar Electrical Vehicles [Pvbs For Sev], Mahmoud Alahmad, Mohamed Amer Chaaban, Lana Chaar

Durham School of Architectural Engineering and Construction: Faculty Publications

In this paper, we propose a new flexible Photovoltaic/Battery charging Structure for Solar Electrical Vehicles (PVBS), where the interconnection of the system is dynamically changing based on current shading conditions across PV modules to provide intelligent system, as well as to provide flexibility, performance, and efficiency enhancement for the SEV. PVBS is expected to 1) provide a battery charging efficiency improvement over existing employed topologies; 2) provide new means to match the computing load with the PV system performance metrics shading and mismatches; 3) and provide elastic reconfigurable system expected to spur research advancements and innovations to make future SEV …

Optimization Of Energy Storage Systems In Hev's, Mahmoud Alahmad, Mohamed Amer Chaaban

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper introduces a novel battery model inspired by molecular structures mainly for applications in HEV’s. This novel 3-D adaptive battery topology shows potential for improvement in input and output performance as well as the charging/ discharging efficiency of batteries. The proposed topology provides flexible connections between battery cells to achieve different configurations of battery. A new switching matrix has been developed to achieve the required configurations. Preliminary simulations provide promising results for an adaptive 3-D battery configuration. Comparison between traditional battery configurations and the adaptive 3-D configuration is considered. A significant improvement in power curves is achieved by the …

Combinatorics & Power Consumption, Mahmoud Alahmad, Wisam Nader

Durham School of Architectural Engineering and Construction: Faculty Publications

in this paper the power consumption possible combinations for a number of loads and a single power source are discussed. The proposed mathematical model depends basically on combinatorics to estimate how many ways are possible to operate different loads powered by a single power source. This paper takes into consideration the different conditions and limitations to operate n number of loads limited by their minimum and maximum values of power consumption. Four different cases of operations are discussed and modeled. A flowchart and a step-by-step method to do the calculations for a general case is also illustrated at the end …

Addressable And Energy Management System For The Built Environment (I), Mahmoud Alahmad, Hosen Hasna Hh, Evans Sordiashie

Durham School of Architectural Engineering and Construction: Faculty Publications

The increasing awareness for a cleaner earth has created more interests in the electric vehicle (EV) technology. Electric vehicles (EVs) will not only cause a reduction in our current greenhouse gas emissions, but also stop or reverse the trend at which our natural resources are being depleted. However, the introduction of the EVs into our societies will still require energy usage in the form of electricity. Integration of charging infrastructures will eventually be required in the built environment for these vehicles. This will add to the current energy consumption in the built environment which will mean more emission of CO2, …

Industry-Experienced Graduate Student Program: Innovative Collaboration In Architectural Engineering At The University Of Nebraska–Lincoln, Clarence E. Waters, Steve Alvine, Michelle L. Eble-Hankins

Durham School of Architectural Engineering and Construction: Faculty Publications

In 2001, the Architectural Engineering Department at the University of Nebraska–Lincoln, along with industry partners, established an industry-experienced graduate student program. The program was developed to bring experienced design professionals to collaborate with the industry while pursuing a Ph.D. in architectural engineering. This program is designed to be mutually beneficial to industry partners, -graduate students, the University of Nebraska–Lincoln Architectural Engineering Department, and the building industry at large. The first doctoral candidate in the program graduated, and significant collaborative work was completed for the industry partner. All parties to this initial offering are pleased with the outcome and believe the …

Lv-11-C031: Measured Levels Of Hospital Noise Before, During, And After Renovation Of A Hospital Wing, And A Survey Of Resulting Patient Perception, Cassandra H. Wiese, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Acoustic conditions in hospitals can negatively influence a patient’s physical and psychological health. This paperreports on noise levels measured before, during, and after renovation of a hospital wing in an Omaha, Nebraska, facility thatregularly receives unsatisfactory noise scores on patient satisfaction surveys. Sound pressure levels were logged every 10seconds over four-day periods in three different locations: at the nurses' station, in the hallway, and in a nearby patient’sroom. The resulting data have been analyzed in terms of A-weighted equivalent sound levels (LAeq) as well as variousexceedance levels (Ln). Results indicate that sound levels did not change much due to the …

Green And Sustainable Technologies For The Built Enviornment, Mahmoud Alahmad, Muhammad Zulfiqar, Hosen Hasna Hh, Hamid Sharif, Evans Sordiashie, Nasser Aljuhaishi

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 and the locations 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 …

Integrating Air Handling Units In Office Buildings For High Performance, Yuebin Yu

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

This study investigates the thermal load features in office buildings and proposes an innovative Integrated Air Handling Unit (IAHU) concept in order to achieve energy savings with conventional office building air handling systems. The corresponding deduction of IAHU for an acceptable Indoor Air Quality (IAQ) and better energy performance is conducted. The system variables and constraints are analyzed in detail to understand the feasibility and operability of IAHU. The control logics and implementation methods are elaborated for typical system layouts. With an IAHU operation, the internal heat gain can be transferred from an interior region into an exterior region in …

Industry Participation In The Interdisciplinary Team Design Project Course Of A Master Of Architectural Engineering Program, Lauren M. Ronsse, Lily M. Wang, Clarence E. Waters

Durham School of Architectural Engineering and Construction: Faculty Publications

This is a case study of extensive industry participation in the capstone design course of the Master of Architectural Engineering program at the University of Nebraska – Lincoln. This course, entitled Interdisciplinary Team Design Project, pairs teams of professional engineers and students to provide mentoring, assessment, and feedback, as the students work on interdisciplinary teams to design the building systems for a real-world project. For the spring 2010 semester, over 33 industry professionals participated in the course, each contributing approximately 40 to 50 hours of mentoring and assessment. This paper describes the course format and industry involvement, which provides students …

Investigation Of Patient Perception Of Hospital Noise And Sound Level Measurements: Before, During, And After Renovations Of A Hospital Wing, Cassandra H. Wiese

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

Acoustic conditions in hospitals have been shown to influence a patient’s physical and psychological health. Noise levels in an Omaha, Nebraska, hospital were measured and compared between various times: before, during, and after renovations of a hospital wing. The renovations included cosmetic changes and the installation of new in-room patient audio-visual systems. Sound pressure levels were logged every 10-seconds over a four-day period in three different locations: at the nurses' station, in the hallway, and in a nearby patient’s room. The resulting data were analyzed in terms of the hourly A-weighted equivalent sound pressure levels (𝐿_𝐴eq) as …

Multi-Channel Orchestral Anechoic Recordings For Auralizations, Michelle C. Vigeant, Lily M. Wang, Jens Holger Rindel, Claus Lynge Christensen, Anders Christian Gade

Durham School of Architectural Engineering and Construction: Faculty Publications

Multi-channel orchestral anechoic recordings were obtained at the Technical University of Denmark (DTU) in June 2005. Every orchestral part of specific movements of two symphonies, Brahms’ Symphony No. 4, 3rd movement, and Mozart’s Symphony No. 40 in g minor, 1st movement, were digitally recorded using five 0.5” DPA microphones, with four surrounding the musicians in the horizontal plane and the fifth directly above. The recordings were made in DTU’s large anechoic chamber, which has free space of about 1000 m3 and a lower frequency limit of 50 Hz. Each musician was recorded individually, and to assist with overall synchronization of …

Examining The Relationships Between Monaural And Binaural Classroom Acoustics Parameters And Student Achievement, Lauren M. Ronsse, Lily M. Wang, Paul L. Sim

Durham School of Architectural Engineering and Construction: Faculty Publications

This study investigates the relationships between several classroom acoustics parameters and student achievement. Detailed binaural room impulse response measurements were conducted in four elementary school classrooms in a midwestern public school system in the United States. Unoccupied background noise levels were also recorded in these spaces. Previous studies have compared how different room acoustics metrics predict speech intelligibility, while another investigation examined perception-based binaural metrics in a typical classroom. This study extends these previous research areas by comparing both binaural classroom acoustics metrics and unoccupied background noise levels to each other and to the standardized student achievement scores of students …

Effects Of Building Mechanical System Noise On Worker Performance And Perception, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper presents results from a number of studies that investigated the effects of noise from building mechanical systems on human task performance and perception. Three phases of research were conducted, each of which utilized a different set of noise signals produced by building mechanical systems: (1) broadband noise at different levels and spectral qualities; (2) tonal noise conditions; and (3) noise conditions with time-varying fluctuations. In each phase, at least six different noise signals (many based on in-situ measurements) were reproduced in an office-like setting. Thirty participants completed tasks (e.g. typing, grammatical reasoning, math) plus subjective questionnaires, while exposed …

Optimum Absorption And Aperture Parameters For Realistic Coupled Volume Spaces Determined From Computational Analysis And Subjective Testing Results, David T. Bradley, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This project utilizes computational modeling to study the effects of varying two architectural parameters, absorption ratio and aperture size, in a realistic coupled volume concert hall. Coupled volumes have been shown to exhibit non-exponential sound energy decay profiles, referred to as double slope effect. A number of objective metrics (T30/T15, LDT/T10, decay ratio, and ΔL) have been used to quantify the double slope effect of the profiles generated in the virtual hall. T30/T15 and LDT/T10 showed similar trends across all hall configurations, indicating decreasing double slope effect with increasing coupled volume absorption ratio for each aperture size, and producing highest …

Computational Modeling Of Effects Of Alloying Elements On Elastic Coefficients, Z. K. Liu, H. Zhang, S. Ganeshan, Y. Wang, S. N. Mathaudhu

Durham School of Architectural Engineering and Construction: Faculty Publications

Models for composition and temperature dependencies of single-crystal elastic stiffness coefficients are developed and applied to the Al₁₂Mg₁₇ and hexagonal closed-packed solution phases in the Mg–Al system based on data from first-principles calculations. In combination with models for multi-phases, the bulk, shear, and Young’s moduli of Mg–Al alloys are predicted and compared with available experimental data in the literature. It is noted that both phase transition and grain boundary sliding may play important roles in the elastic coefficients as a function of temperature.

Ab-10-018: The Effects Of Noise From Building Mechanical Systems With Tonal Components On Human Performance And Perception (1322-Rp), Erica E. Ryherd, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This study investigated the effects of noise from building mechanical systems with tonal components on human task performance and perception. Six different noise conditions based on in-situ measurements were reproduced in an office-like setting; all were set to approximately the same sound level (47 dBA) but could have one particular tonal frequency (120 Hz, 235 Hz, or 595 Hz) at one of two tonal prominence ratios (5 or 9). Thirty participants were asked to complete typing, grammatical reasoning, and math tasks plus subjective questionnaires, while being exposed for approximately 1 hour to each noise condition. Results show that the noise …

Ab-10-019: Human Performance And Perception-Based Evaluations Of Indoor Noise Criteria For Rating Mechanical System Noise With Time-Varying Fluctuations (1322-Rp), Lily M. Wang, Cathleen C. Novak

Durham School of Architectural Engineering and Construction: Faculty Publications

The goal of this study was to investigate the effects of noise from building mechanical systems with time-varying fluctuations on human task performance and perception, and to determine how well current indoor noise rating methods account for this performance and perception. Six different noise conditions with varying degrees of time-varying fluctuations, many focused in the low frequency rumble region, were reproduced in an office-like setting. Thirty participants were asked to complete typing, grammatical reasoning, and math tasks plus subjective questionnaires, while being exposed for approximately one hour to each noise condition. Results show that the noise conditions with higher sound …

Ab-10-C037: Effects Of Noise From Building Mechanical Systems On Elementary School Student Achievement, Lauren M. Ronsse, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This project seeks to determine what relationship, if any, exists betweenbackground noise levels in elementary classrooms due to the building mechanicalsystems and student performance on achievement tests. Previous research inclassroom acoustics has clearly identified that lower background noise levelsresult in higher speech intelligibility which is crucial for the learning process;however, there is a lack of data correlating lower noise levels to improved studentachievement scores. For this study, background noise level measurements were madein 14 elementary schools in a public school system in Council Bluffs, Iowa, USA.The measurements were made in unoccupied classrooms with the central buildingmechanical systems activated. Second and …

Active Noise Barrier Minimizing Pressure Gradient, Carl Hart, Siu-Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

Minimization of the sound pressure field within the shadow zone of a noise barrier is achieved by reducing the pressure gradient along a line, at the top of a barrier, via active noise control. The noise control effectiveness of a barrier is increased by this strategy, especially for specific system configurations. The proposed method was evaluated by numerical simulation. Results indicate that system orientation has little effect on minimizing the pressure gradient at the top of the barrier when the error sensors are invisible to the primary noise disturbance. Highly effective control within the shadow zone and close to the …

Noise Propagation Through Open Windows Of Finite Depth Into An Enclosure, Caleb Sieck, Siu-Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

Predicting the insertion loss of an opening backed with an enclosed space is important for building noise control. Recent research in sound transmission through apertures of finite depth in infinite rigid baffles has included the effects of propagating and evanescent modes within the aperture in order to extend models to higher frequencies. The present study extends the model to the case of the aperture backed by a cavity as opposed to sound radiating into half-space. The role of coupling between the aperture modes, radiation modes, and cavity modes in the transmission was investigated. The results were compared to those of …

Feasibility Study Of Solar Driven Underground Cooling System, Michel E. Shafik

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

In the United States the peak electrical use occurs during the summer. In addition, the building sector consumes a major portion of the annual electrical energy consumption. One of the main energy consuming components in the building sector is the Heating, Ventilation, and Air-Conditioning (HVAC) systems. This research studies the feasibility of implementing a solar driven underground cooling system that could contribute to reducing building cooling loads. The developed system consists of an Earth-to-Air Heat Exchanger (EAHE) coupled with a solar chimney that provides a natural cool draft to the test facility building at the Solar Energy Research Test Facility …

Ab-10-017: Combined Effects Of Noise And Temperature On Human Comfort And Performance (1128-Rp), Dale Tiller, Lily M. Wang, Amy Musser, Matthew Radik

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper summarizes results from an experiment designed to investigate the combined effects of noise and temperature on human thermal comfort and task performance. Thirty subjects (16 females, 14 males) were exposed to all combinations of five thermal conditions (PMV +1 [79.6°F:26.4°C], PMV +0.5 [75.8°F:24.3°C], PMV 0 [72.1°F:22.3°C], PMV -0.5 [68.3°F:20.2°C], and PMV -1 [64.6°F:18.1°C]), three RC noise levels (RC-30, RC-40, and RC-50), and two sound qualities (neutral and rumbly): all sounds mimicked noise from building ventilation systems. After a one-hour adaptation period at each condition, subjects rated their thermal comfort using the ASHRAE Thermal Comfort Scale and the Tenant …

Subjective Impression Of Discomfort Glare From Sources Of Non-Uniform Luminance, Michelle L. Eble-Hankins

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

The intent of this study was to further investigate the effects of spatial frequency and position on discomfort glare. Most of the discomfort research in the past has used sources of uniform luminance, so not much is known about how non-uniformity affects the perception of glare. An apparatus was designed and built specifically for this study, but it was also designed to have significant flexibility for future work. Two different experiments were performed with this apparatus: a paired comparison experiment; and, a rating scale experiment. For both experiments, 6 levels of spatial frequency and 4 levels of position were studied. …

Implications Of Human Performance And Perception Under Tonal Noise Conditions On Indoor Noise Criteria, Lily M. Wang, Erica E. Ryherd

Durham School of Architectural Engineering and Construction: Faculty Publications

This research investigated differences in task performance and perception under six non-time-varying ventilation-type background noise spectra with differing tonality. The results were related to five indoor noise criteria systems: Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC-Mark II), and the A-weighted equivalent sound pressure level (L_Aeq). These criteria systems are commonly used in the U.S. building industry, but concerns exist over whether they are appropriate for all noise situations. Thirty test subjects completed three types of performance tasks (typing, reasoning, and math) and answered questions about their perception of the indoor …

Demand-Based Optimal Control To Save Energy: A Case-Study In A Medical Center, Ik-Seong Joo, Li Song, Mingsheng Liu, Mike Carico

Durham School of Architectural Engineering and Construction: Faculty Publications

Continuous Commissioning^® (CC^®) strategies include reducing simultaneous heating and cooling, scheduling the facility’s occupancy needs, utilizing free cooling, and minimizing excessive supply air and outside air. Most significantly, this demandbased control energy conservation strategy can facilitate mechanical system performance at near optimal conditions through the gradual advancement of control systems and the ability of upstream systems reading the status of downstream systems.

This paper demonstrates demand-based temperature, pressure and economizer control by the mathematical optimization methodology illustrated by a case-study, implemented with actual systems in a 1.2 million square foot medical center. Based on the optimization results, …

Optimal Control In Three-Deck Multi-Zone Air-Handling Units: A Case-Study, Ik-Seong Joo, Li Song, Mingsheng Liu, Barry Douglas

Durham School of Architectural Engineering and Construction: Faculty Publications

A multi-zone air-handling unit was popular several decades ago due to the convenience of small sized modular units, which were inexpensive to install and easily maintained in a mechanical room. The cost and convenience proved to be of little benefit as the units perform poorly from an energy usage perspective. A “three-deck” multi-zone unit is a hybrid of its kind, and it can be very efficient when controlled properly. In theory, there will not be simultaneous heating and cooling if its heating damper is controlled separately from the control of the cooling damper. When the zone load is neutral (not …

Evaluation Of A Virtual Refrigerant Charge Sensor, Woohyun Kim, James E. Braun, Haorong Li

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper presents a thorough evaluation of a method for determining refrigerant charge that employs low-cost, non-invasive measurements (i.e., surface mounted temperature measurements). The method could be used as part of a protocol for verified service providers (VSPs) in AC diagnostic tune-up or refrigerant charge, air flow (RCA) verification programs. Ultimately, the method could be embedded within a portable virtual refrigerant charge gauge for a technician’s use or permanently installed on the AC unit. The accuracy of the virtual refrigerant charge sensor method is evaluated in this paper using laboratory data for a number of different systems and over a …

Investigations Of Multi-Channel Auralization Technique For Various Orchestra Arrangements, With Phase-Shifted String Sections, Michelle C Vigeant, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

An orchestra can be simulated in room acoustics computer modelling using a variety of methods, ranging from a single omni-directional source to individual sources of all instruments. This study utilizes the method of individual sources for each instrument, but with reduced source representation for the string sections. The anechoic recordings used in this investigation are five-channel recordings, which capture the source directivity of the individual instruments. For each string section, the individual anechoic recordings were phase shifted several times, up to 23 ms, and combined to create a single recording for use in the simulations. An orchestra was simulated in …