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- Genre: Masters Thesis
- Creators: Rogers, Bradley
- Member of: ASU Electronic Theses and Dissertations
Description
Smoke entering a flight deck cabin has been an issue for commercial aircraft for many years. The issue for a flight crew is how to mitigate the smoke so that they can safely fly the aircraft. For this thesis, the feasibility of having a Negative Pressure System that utilizes the cabin altitude pressure and outside altitude pressure to remove smoke from a flight deck was studied. Existing procedures for flight crews call for a descent down to a safe level for depressurizing the aircraft before taking further action. This process takes crucial time that is critical to the flight crew's ability to keep aware of the situation. This process involves a flight crews coordination and fast thinking to manually take control of the aircraft; which has become increasing more difficult due to the advancements in aircraft automation. Unfortunately this is the only accepted procedure that is used by a flight crew. Other products merely displace the smoke. This displacement is after the time it takes for the flight crew to set up the smoke displacement unit with no guarantee that a flight crew will be able to see or use all of the aircraft's controls. The Negative Pressure System will work automatically and not only use similar components already found on the aircraft, but work in conjunction with the smoke detection system and pressurization system so smoke removal can begin without having to descend down to a lower altitude. In order for this system to work correctly many factors must be taken into consideration. The size of a flight deck varies from aircraft to aircraft, therefore the ability for the system to efficiently remove smoke from an aircraft is taken into consideration. For the system to be feasible on an aircraft the cost and weight must be taken into consideration as the added fuel consumption due to weight of the system may be the limiting factor for installing such a system on commercial aircraft.
ContributorsDavies, Russell (Author) / Rogers, Bradley (Thesis advisor) / Palmgren, Dale (Committee member) / Rajadas, John (Committee member) / Arizona State University (Publisher)
Created2013
Description
Photovoltaic (PV) module nameplates typically provide the module's electrical characteristics at standard test conditions (STC). The STC conditions are: irradiance of 1000 W/m2, cell temperature of 25oC and sunlight spectrum at air mass 1.5. However, modules in the field experience a wide range of environmental conditions which affect their electrical characteristics and render the nameplate data insufficient in determining a module's overall, actual field performance. To make sound technical and financial decisions, designers and investors need additional performance data to determine the energy produced by modules operating under various field conditions. The angle of incidence (AOI) of sunlight on PV modules is one of the major parameters which dictate the amount of light reaching the solar cells. The experiment was carried out at the Arizona State University- Photovoltaic Reliability Laboratory (ASU-PRL). The data obtained was processed in accordance with the IEC 61853-2 model to obtain relative optical response of the modules (response which does not include the cosine effect). The results were then compared with theoretical models for air-glass interface and also with the empirical model developed by Sandia National Laboratories. The results showed that all modules with glass as the superstrate had identical optical response and were in agreement with both the IEC 61853-2 model and other theoretical and empirical models. The performance degradation of module over years of exposure in the field is dependent upon factors such as environmental conditions, system configuration, etc. Analyzing the degradation of power and other related performance parameters over time will provide vital information regarding possible degradation rates and mechanisms of the modules. An extensive study was conducted by previous ASU-PRL students on approximately 1700 modules which have over 13 years of hot- dry climatic field condition. An analysis of the results obtained in previous ASU-PRL studies show that the major degradation in crystalline silicon modules having glass/polymer construction is encapsulant discoloration (causing short circuit current drop) and solder bond degradation (causing fill factor drop due to series resistance increase). The power degradation for crystalline silicon modules having glass/glass construction was primarily attributed to encapsulant delamination (causing open-circuit voltage drop).
ContributorsVasantha Janakeeraman, Suryanarayana (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Rogers, Bradley (Committee member) / Macia, Narciso (Committee member) / Arizona State University (Publisher)
Created2013
Description
The object of this study was a 26 year old residential Photovoltaic (PV) monocrystalline silicon (c-Si) power plant, called Solar One, built by developer John F. Long in Phoenix, Arizona (a hot-dry field condition). The task for Arizona State University Photovoltaic Reliability Laboratory (ASU-PRL) graduate students was to evaluate the power plant through visual inspection, electrical performance, and infrared thermography. The purpose of this evaluation was to measure and understand the extent of degradation to the system along with the identification of the failure modes in this hot-dry climatic condition. This 4000 module bipolar system was originally installed with a 200 kW DC output of PV array (17 degree fixed tilt) and an AC output of 175 kVA. The system was shown to degrade approximately at a rate of 2.3% per year with no apparent potential induced degradation (PID) effect. The power plant is made of two arrays, the north array and the south array. Due to a limited time frame to execute this large project, this work was performed by two masters students (Jonathan Belmont and Kolapo Olakonu) and the test results are presented in two masters theses. This thesis presents the results obtained on the north array and the other thesis presents the results obtained on the south array. The resulting study showed that PV module design, array configuration, vandalism, installation methods and Arizona environmental conditions have had an effect on this system's longevity and reliability. Ultimately, encapsulation browning, higher series resistance (potentially due to solder bond fatigue) and non-cell interconnect ribbon breakages outside the modules were determined to be the primary causes for the power loss.
ContributorsBelmont, Jonathan (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Henderson, Mark (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2013
Description
Potential induced degradation (PID) due to high system voltages is one of the major degradation mechanisms in photovoltaic (PV) modules, adversely affecting their performance due to the combined effects of the following factors: system voltage, superstrate/glass surface conductivity, encapsulant conductivity, silicon nitride anti-reflection coating property and interface property (glass/encapsulant; encapsulant/cell; encapsulant/backsheet). Previous studies carried out at ASU's Photovoltaic Reliability Laboratory (ASU-PRL) showed that only negative voltage bias (positive grounded systems) adversely affects the performance of commonly available crystalline silicon modules. In previous studies, the surface conductivity of the glass surface was obtained using either conductive carbon layer extending from the glass surface to the frame or humidity inside an environmental chamber. This thesis investigates the influence of glass surface conductivity disruption on PV modules. In this study, conductive carbon was applied only on the module's glass surface without extending to the frame and the surface conductivity was disrupted (no carbon layer) at 2cm distance from the periphery of frame inner edges. This study was carried out under dry heat at two different temperatures (60 °C and 85 °C) and three different negative bias voltages (-300V, -400V, and -600V). To replicate closeness to the field conditions, half of the selected modules were pre-stressed under damp heat for 1000 hours (DH 1000) and the remaining half under 200 hours of thermal cycling (TC 200). When the surface continuity was disrupted by maintaining a 2 cm gap from the frame to the edge of the conductive layer, as demonstrated in this study, the degradation was found to be absent or negligibly small even after 35 hours of negative bias at elevated temperatures. This preliminary study appears to indicate that the modules could become immune to PID losses if the continuity of the glass surface conductivity is disrupted at the inside boundary of the frame. The surface conductivity of the glass, due to water layer formation in a humid condition, close to the frame could be disrupted just by applying a water repelling (hydrophobic) but high transmittance surface coating (such as Teflon) or modifying the frame/glass edges with water repellent properties.
ContributorsTatapudi, Sai Ravi Vasista (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Srinivasan, Devarajan (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABSTRACT As the use of photovoltaic (PV) modules in large power plants continues to increase globally, more studies on degradation, reliability, failure modes, and mechanisms of field aged modules are needed to predict module life expectancy based on accelerated lifetime testing of PV modules. In this work, a 26+ year old PV power plant in Phoenix, Arizona has been evaluated for performance, reliability, and durability. The PV power plant, called Solar One, is owned and operated by John F. Long's homeowners association. It is a 200 kWdc, standard test conditions (STC) rated power plant comprised of 4000 PV modules or frameless laminates, in 100 panel groups (rated at 175 kWac). The power plant is made of two center-tapped bipolar arrays, the north array and the south array. Due to a limited time frame to execute this large project, this work was performed by two masters students (Jonathan Belmont and Kolapo Olakonu) and the test results are presented in two masters theses. This thesis presents the results obtained on the south array and the other thesis presents the results obtained on the north array. Each of these two arrays is made of four sub arrays, the east sub arrays (positive and negative polarities) and the west sub arrays (positive and negative polarities), making up eight sub arrays. The evaluation and analyses of the power plant included in this thesis consists of: visual inspection, electrical performance measurements, and infrared thermography. A possible presence of potential induced degradation (PID) due to potential difference between ground and strings was also investigated. Some installation practices were also studied and found to contribute to the power loss observed in this investigation. The power output measured in 2011 for all eight sub arrays at STC is approximately 76 kWdc and represents a power loss of 62% (from 200 kW to 76 kW) over 26+ years. The 2011 measured power output for the four south sub arrays at STC is 39 kWdc and represents a power loss of 61% (from 100 kW to 39 kW) over 26+ years. Encapsulation browning and non-cell interconnect ribbon breakages were determined to be the primary causes for the power loss.
ContributorsOlakonu, Kolapo (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Srinivasan, Devarajan (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2012
Description
While the piezoelectric effect has been around for some time, it has only recently caught interest as a potential sustainable energy harvesting device. Piezoelectric energy harvesting has been developed for shoes and panels, but has yet to be integrated into a marketable bicycle tire. For this thesis, the development and feasibility of a piezoelectric tire was done. This includes the development of a circuit that incorporates piezoceramic elements, energy harvesting circuitry, and an energy storage device. A single phase circuit was designed using an ac-dc diode rectifier. An electrolytic capacitor was used as the energy storage device. A financial feasibility was also done to determine targets for manufacturing cost and sales price. These models take into account market trends for high performance tires, economies of scale, and the possibility of government subsidies. This research will help understand the potential for the marketability of a piezoelectric energy harvesting tire that can create electricity for remote use. This study found that there are many obstacles that must be addressed before a piezoelectric tire can be marketed to the general public. The power output of this device is miniscule compared to an alkaline battery. In order for this device to approach the power output of an alkaline battery the weight of the device would also become an issue. Additionally this device is very costly compared to the average bicycle tire. Lastly, this device is extreme fragile and easily broken. In order for this device to become marketable the issues of power output, cost, weight, and durability must all be successfully overcome.
ContributorsMalotte, Christopher (Author) / Madakannan, Arunachalanadar (Thesis advisor) / Srinivasan, Devarajan (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2012
Description
With the growth of IT products and sophisticated software in various operating systems, I observe that security risks in systems are skyrocketing constantly. Consequently, Security Assessment is now considered as one of primary security mechanisms to measure assurance of systems since systems that are not compliant with security requirements may lead adversaries to access critical information by circumventing security practices. In order to ensure security, considerable efforts have been spent to develop security regulations by facilitating security best-practices. Applying shared security standards to the system is critical to understand vulnerabilities and prevent well-known threats from exploiting vulnerabilities. However, many end users tend to change configurations of their systems without paying attention to the security. Hence, it is not straightforward to protect systems from being changed by unconscious users in a timely manner. Detecting the installation of harmful applications is not sufficient since attackers may exploit risky software as well as commonly used software. In addition, checking the assurance of security configurations periodically is disadvantageous in terms of time and cost due to zero-day attacks and the timing attacks that can leverage the window between each security checks. Therefore, event-driven monitoring approach is critical to continuously assess security of a target system without ignoring a particular window between security checks and lessen the burden of exhausted task to inspect the entire configurations in the system. Furthermore, the system should be able to generate a vulnerability report for any change initiated by a user if such changes refer to the requirements in the standards and turn out to be vulnerable. Assessing various systems in distributed environments also requires to consistently applying standards to each environment. Such a uniformed consistent assessment is important because the way of assessment approach for detecting security vulnerabilities may vary across applications and operating systems. In this thesis, I introduce an automated event-driven security assessment framework to overcome and accommodate the aforementioned issues. I also discuss the implementation details that are based on the commercial-off-the-self technologies and testbed being established to evaluate approach. Besides, I describe evaluation results that demonstrate the effectiveness and practicality of the approaches.
ContributorsSeo, Jeong-Jin (Author) / Ahn, Gail-Joon (Thesis advisor) / Yau, Stephen S. (Committee member) / Lee, Joohyung (Committee member) / Arizona State University (Publisher)
Created2014
Description
Access control is necessary for information assurance in many of today's applications such as banking and electronic health record. Access control breaches are critical security problems that can result from unintended and improper implementation of security policies. Security testing can help identify security vulnerabilities early and avoid unexpected expensive cost in handling breaches for security architects and security engineers. The process of security testing which involves creating tests that effectively examine vulnerabilities is a challenging task. Role-Based Access Control (RBAC) has been widely adopted to support fine-grained access control. However, in practice, due to its complexity including role management, role hierarchy with hundreds of roles, and their associated privileges and users, systematically testing RBAC systems is crucial to ensure the security in various domains ranging from cyber-infrastructure to mission-critical applications. In this thesis, we introduce i) a security testing technique for RBAC systems considering the principle of maximum privileges, the structure of the role hierarchy, and a new security test coverage criterion; ii) a MTBDD (Multi-Terminal Binary Decision Diagram) based representation of RBAC security policy including RHMTBDD (Role Hierarchy MTBDD) to efficiently generate effective positive and negative security test cases; and iii) a security testing framework which takes an XACML-based RBAC security policy as an input, parses it into a RHMTBDD representation and then generates positive and negative test cases. We also demonstrate the efficacy of our approach through case studies.
ContributorsGupta, Poonam (Author) / Ahn, Gail-Joon (Thesis advisor) / Collofello, James (Committee member) / Huang, Dijiang (Committee member) / Arizona State University (Publisher)
Created2014
Description
This is a two-part thesis: Part 1 of this thesis tests and validates the methodology and mathematical models of the International Electrotechnical Commission (IEC) 61853-2 standard for the measurement of angle of incidence (AOI) effects on photovoltaic modules. Flat-plate photovoltaic modules in the field operate under a wide range of environmental conditions. The purpose of IEC 61853-2 is to characterize photovoltaic modules' performance under specific environmental conditions. Part 1 of this report focuses specifically on AOI. To accurately test and validate IEC 61853-2 standard for measuring AOI, meticulous experimental setup and test procedures were followed. Modules of five different photovoltaic technology types with glass superstrates were tested. Test results show practically identical relative light transmission plots for all five test modules. The experimental results were compared to theoretical and empirical models for relative light transmission of air-glass interface. IEC 61853-2 states "for the flat glass superstrate modules, the AOI test does not need to be performed; rather, the data of a flat glass air interface can be used." The results obtained in this thesis validate this statement. This work was performed in collaboration with another Master of Science student (Surynarayana Janakeeraman) and the test results are presented in two masters theses. Part 2 of this thesis is to develop non-intrusive techniques to accurately measure the quantum efficiency (QE) of a single-junction crystalline silicon cell within a commercial module. This thesis will describe in detail all the equipment and conditions necessary to measure QE and discuss the factors which may influence this measurement. The ability to utilize a non-intrusive test to measure quantum efficiency of a cell within a module is extremely beneficial for reliability testing of commercial modules. Detailed methodologies for this innovative test procedure are not widely available in industry because equipment and measurement techniques have not been explored extensively. This paper will provide a literature review describing relevant theories and measurement techniques related to measuring the QE of a cell within a module. The testing methodology and necessary equipment will be described in detail. Results and conclusions provide the overall accuracy of the measurements and discuss the parameters affecting these measurements.
ContributorsKnisely, Brett (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Rogers, Bradley (Committee member) / Macia, Narciso (Committee member) / Arizona State University (Publisher)
Created2013
Description
The digital forensics community has neglected email forensics as a process, despite the fact that email remains an important tool in the commission of crime. Current forensic practices focus mostly on that of disk forensics, while email forensics is left as an analysis task stemming from that practice. As there is no well-defined process to be used for email forensics the comprehensiveness, extensibility of tools, uniformity of evidence, usefulness in collaborative/distributed environments, and consistency of investigations are hindered. At present, there exists little support for discovering, acquiring, and representing web-based email, despite its widespread use. To remedy this, a systematic process which includes discovering, acquiring, and representing web-based email for email forensics which is integrated into the normal forensic analysis workflow, and which accommodates the distinct characteristics of email evidence will be presented. This process focuses on detecting the presence of non-obvious artifacts related to email accounts, retrieving the data from the service provider, and representing email in a well-structured format based on existing standards. As a result, developers and organizations can collaboratively create and use analysis tools that can analyze email evidence from any source in the same fashion and the examiner can access additional data relevant to their forensic cases. Following, an extensible framework implementing this novel process-driven approach has been implemented in an attempt to address the problems of comprehensiveness, extensibility, uniformity, collaboration/distribution, and consistency within forensic investigations involving email evidence.
ContributorsPaglierani, Justin W (Author) / Ahn, Gail-Joon (Thesis advisor) / Yau, Stephen S. (Committee member) / Santanam, Raghu T (Committee member) / Arizona State University (Publisher)
Created2013