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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A photogrammetric on-orbit inspection for orbiter thermal protection system

Gesting, Peter Paul 12 April 2006 (has links)
Due to the Columbia Space Shuttle Accident of February 2003, the Columbia Accident Investigation Board determined the need for an on-orbit inspection system for the Thermal Protection System that accurately determines damage depth to 0.25". NASA contracted the Spacecraft Technology Center in College Station, Texas, for a proof-of-concept photogrammetric system. This system involves a high quality digital camera placed on the International Space Station, capable of taking high fidelity images of the orbiter as it rotates through the Rendezvous Pitch Maneuver. Due to the pitch rotation, the images are tilted at different angles. The tilt causes the damage to exhibit parallax between multiple images. The tilted images are therefore registered to the near-vertical images using visually striking features on the undamaged surface of the Thermal Protection System that appear in multiple images taken at different tilt angles. The images become relatively oriented after registration, and features in one image are ensured to lie on the epipolar line in the other images. Features that do not lie on the undamaged surface, however, are shifted in the tilted images. These pixels are matched to the near-vertical image using a sliding-window area-matching approach. The windows are matched using a least-squares error method. The change in location for a pixel in a tilted image from its expected location on the undamaged surface is called the pixel disparity. This disparity is linearly scaled using the tilt angle and the pixel sampling to determine the depth of the damage at that pixel location. The algorithm is tested on a set of damaged tiles at the Johnson Space Center in Houston and the photogrammetric damage depth is then compared to a set of truth data provided by NASA. The photogrammetric method shows promise, with the 0.25" error limit being exceeded in only a few pixel locations. Once the camera properties are fully known from calibration, this systematic error should be reduced.
2

Optimizations of Battery-Based Intrusion Protection Systems

Nelson, Theresa Michelle 03 June 2008 (has links)
As time progresses, small mobile devices become more prevalent for both personal and industrial use, providing malicious network users with new and exciting venues for security exploits. Standard security applications, such as Norton Antivirus and MacAfee, require computing power, memory space, and operating system complexity that are not present in small mobile devices. Recently, the Battery-Sensing Intrusion Protection System (B-SIPS) was devised as a means to correct the inability of small mobile devices to protect themselves against network attacks. The B-SIPS application uses smart battery data in conjunction with process and network information to determine whether the mobile device is experiencing a battery depletion attack. Additionally, B-SIPS provides mobile device statistics to system administrators such that they can analyze the state of the wireless network more thoroughly. The research presented in this thesis collaborates with and extends the B-SIPS research through optimizations and validation. Areas of focus include ensuring public acceptance of the application through the implementation of a usability study and verifying that the deployment of the application will not jeopardize the performance of external mobile device applications. Additionally, this thesis describes how GUI optimizations are realized for both the B-SIPS client and CIDE server, how future smart battery hardware implementations are introduced for increased effectiveness with the B-SIPS application, and it discusses how an optimum deployment data transmission period is determined. / Master of Science
3

Investigation of Subsonic and Supersonic Flow Characteristics of an Inductively Coupled Plasma Facility

Smith, Silas 19 September 2013 (has links)
Inductively Coupled Plasma (ICP) facilities create high enthalpy ows to recreate atmospheric entry conditions. Although no condition has been duplicated exactly in a ground test facility, it is important to characterize the condition to understand how close a facility can come to doing so. An ICP facility was constructed at the University of Vermont for aerospace material testing in 2010. The current setup can operate using air, carbon dioxide, nitrogen, and argon to test samples in a chamber. In this work we investigate di erent ways to increase measured heat ux and expand our facility to operate supersonically. To do so, a water cooled injection system was designed to overcome failure points of the prior system. An investigation of heat ux methods that provide a baseline for the facility were also examined and tested. A nozzle con guration was also developed with an overall goal of increasing the plasma ow to reach sonic and supersonic velocities, allowing it to be compared with the existing subsonic system. An iterative approach was taken to develop a nozzle design that is robust enough to handle the harsh environment, yet adaptable to the pre-existing facility components. The current design uses interchangeable sonic and supersonic nozzles which also allow for appropriate plasma gas expansion. Data are taken through retractable and goose-neck probe sample holders during testing. Heat ux can be determined by use of a Gardon gage, slug calorimeter, and water cooled calorimeter. Total and static pressure are determined from a pitot tube and pressure tap, which are then manipulated into a velocity measurement. A comparison between subsonic and supersonic operation is then made with these data. Existing literature uses correlations between jet diameter and velocity gradients to determine the e ective heat ux. This investigation found that the experimental and theoretical heat ux results scale correctly according to the correlations.
4

A Study on Protection System for Workers Incurring Occupational Accidents in Taiwan

Weng, Mei-ling 27 August 2006 (has links)
The related and sound method, juridical protection, prevention, compensation and reconstruction for the whole domestic occupational accident labor protection system, currently lack of more thorough research on it. In order to understand the problem of occupational accident labor protection system, this study was adopted by qualitative in-depth interviews and comparatively second data to analyze subsidies of the implements, current method evaluations and influences of the administration for occupational accident labor protection system. There were 18 interviews, who divided into 4 categories including 3 administrators, 2 workers, 6 managers and other scholars. In view of interviews and related theories, the study examined occupational accident labor protection system in Taiwan, and concluded on the following chapters: 1.According to Occupational Accident Labor Protection Act and its Enforcement Rules, these relativity compiled related laws and regulations through the website¡]intranet¡^that integrated the database of information. It was not only convenient for workers to find out various rights of this Act, but also modified related Occupational Accident Labor Protection Act and regulations, build up more complete occupational accident labor protection system and reformed the direction for juridical protection. Firstly, the prevention of occupational accidents was for workers; Secondly, the responsibility of compensation was undertaken by the social insurance, moreover the atypical employment need to be protected and esteemed in the field of occupational accidents. 2.The implemented system of the occupation accident prevention needs to be strengthened, carrying out educational safety and health training, creating enterprise safety and health culture, re-examining the related regulations, and solving the managed problems of machinery or equipment determined to be potentially dangerous. To look into the policies of construction industry with the constructing of safety problems, identify the explicit standard basis of occupation accidents, build up complete supervising system of the occupation accidents, promote the quality of the labor health inspection, enhance the prevention of occupation health, and gives workers e a predominant position for safety and health. 3.The subsidies of occupation accidents were allocated according to the tendency of ¡§need", increasing family subsidies for occupation accidents, preventing from receiving various subsidies before the family problems were happened, strengthening the implementation of the occupation accidents for employer compensation system. 4.It carefully sets up the complete reconstructed system of occupation accidents, enhances occupation reconstruction, builds up the assessed mode of occupation accidents with the damaged degree of workers, integrates the welfare services of medical treatment, labor affairs, and social affairs, and constructs the perfect and complete mechanism of rebuilt occupation accidents. According to this study, the suggestion and reform of occupational accident labor protection system were presented as followed: 1.In legislative views: In the short-term goal, the various regulations of occupational accident subsidies have to be simplified with one-way law or regulation, and in the long-term goal, it need draw up "the occupational accident insurance act" in the future. 2.In administrative views: (1)With revising each regulation related occupational accident labor protection, the labor dispatched protection law will be enacted that strengthens the worker¡¦s rights and protections for the atypical employment model in the occurrence of occupational accident labor protection. (2)The resolving problems of occupational accident labor protection system include: we have to strengthen educational safety and healthy training, resolve potentially dangerous machinery or equipment managed problems, solve construction industry building safe problems, re-examine occupational accident identified problems, reviser complete related regulations of occupational accident supervisory system, amend the quality of labor physical examinations, enhance the labor safety and health guidance and inspection, resolve occupational accident insurance benefits and subsidizing procedures and build up complete the reconstruction of occupation accident system. 3.The subsidies of occupation accidents were allocated according to the tendency of ¡§need¡¨, increasing family subsidies for occupation accidents, preventing from receiving various subsidies before the family problems were happened, strengthening the implementation of the occupation accidents for employer compensation system. 4.In employee views: Workers have the good habit of working safety and strengthen related occupation accident labor protection system and measure, coagulate union consciousness, express collective efforts, by means of the negotiation of labor union and the employer to fight for their benefits and rights.
5

Coupling of Fluid Thermal Simulation for Nonablating Hypersonic Reentry Vehicles Using Commercial Codes FLUENT and LS-DYNA

Sockalingam, Subramani 22 September 2008 (has links)
No description available.
6

Evaluation and verification of an architecture suitable for a multi-unit control room of a pebble bed high temperature reactor nuclear power plant / Herman Visagie

Visagie, Herman January 2015 (has links)
Current regulations specify the minimum number of operators required per nuclear power plant. However, these requirements are based on the operation of large nuclear power plants, which are not inherent safe and can result in a meltdown. For newly developed small nuclear reactors, the current number of operators seems to be excessive causing the technology to be less competitive. Before the number of required operators can be optimised, it should be demonstrated that human errors will not endanger or cause risk to the plant or public. For this study, a small pebble bed High Temperature Reactor (HTR) Nuclear Power Plant (NPP), the Th-100, was evaluated. The inherent safety features of this type of nuclear reactor include independent barriers for fission product capture and passive heat dissipation during a loss of coolant. The control and instrumentation architecture include two independent protection systems. The Control and Limitation System is the first protection system to react if the reactor parameters exceed those of the normal operational safe zone. If the Control and Limitation System fail to maintain the reactor within the safe zone, the Reactor Protection System would at that time operate and force the reactor to a safe state. Both these automated protection systems are installed in a control room local to the reactor building, protected from adverse conditions. In addition, it is connected to a semi-remote control room, anticipated as a multi-unit control room to include the monitoring and control of the auxiliary systems. Probable case studies of human error associated with multi-unit control rooms were evaluated against the logic of the Control and Limitation System. Fault Tree Analysis was used to investigate all possible failures. The evaluation determined the reliability of the Control and Limitation System and highlighted areas which design engineers should take into account if a higher reliability is required. The scenario was expanded, applying the same methods, to include the large release of fission products in order to verify the reliability calculations. The probability of a large release of fission products compared with studies done on other nuclear installations revealed to be much less for the evaluated HTR as was expected. As the study has proved that human error cannot have a negative influence on the safety of the reactor, it can be concluded that the first step has been met which is required, when applying for a waiver to utilise a multi-unit control room for the small pebble bed HTR NPP. Also, from the study, it is recommended that a practical approach be applied for the evaluation of operator duties on a live plant, to optimise the number of operators required. This in turn will position the inherent safe HTR competitively over other power stations. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2015
7

Evaluation and verification of an architecture suitable for a multi-unit control room of a pebble bed high temperature reactor nuclear power plant / Herman Visagie

Visagie, Herman January 2015 (has links)
Current regulations specify the minimum number of operators required per nuclear power plant. However, these requirements are based on the operation of large nuclear power plants, which are not inherent safe and can result in a meltdown. For newly developed small nuclear reactors, the current number of operators seems to be excessive causing the technology to be less competitive. Before the number of required operators can be optimised, it should be demonstrated that human errors will not endanger or cause risk to the plant or public. For this study, a small pebble bed High Temperature Reactor (HTR) Nuclear Power Plant (NPP), the Th-100, was evaluated. The inherent safety features of this type of nuclear reactor include independent barriers for fission product capture and passive heat dissipation during a loss of coolant. The control and instrumentation architecture include two independent protection systems. The Control and Limitation System is the first protection system to react if the reactor parameters exceed those of the normal operational safe zone. If the Control and Limitation System fail to maintain the reactor within the safe zone, the Reactor Protection System would at that time operate and force the reactor to a safe state. Both these automated protection systems are installed in a control room local to the reactor building, protected from adverse conditions. In addition, it is connected to a semi-remote control room, anticipated as a multi-unit control room to include the monitoring and control of the auxiliary systems. Probable case studies of human error associated with multi-unit control rooms were evaluated against the logic of the Control and Limitation System. Fault Tree Analysis was used to investigate all possible failures. The evaluation determined the reliability of the Control and Limitation System and highlighted areas which design engineers should take into account if a higher reliability is required. The scenario was expanded, applying the same methods, to include the large release of fission products in order to verify the reliability calculations. The probability of a large release of fission products compared with studies done on other nuclear installations revealed to be much less for the evaluated HTR as was expected. As the study has proved that human error cannot have a negative influence on the safety of the reactor, it can be concluded that the first step has been met which is required, when applying for a waiver to utilise a multi-unit control room for the small pebble bed HTR NPP. Also, from the study, it is recommended that a practical approach be applied for the evaluation of operator duties on a live plant, to optimise the number of operators required. This in turn will position the inherent safe HTR competitively over other power stations. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2015
8

'n Interagentskap-aanmeldingsprotokol vir die kinderbeskermingstelsel in die Vrystaat / Martha Levina van der Schyff

Van der Schyff, Martha Levina January 2014 (has links)
The overall purpose of this research was to develop an inter-agency reporting protocol for the child protection system in the Free State. The aim was to integrate current legislation and policy into this inter-agency reporting protocol to create standardised reporting procedures to ensure effective access to and response from the child protection system for the child in need of care and protection. The thesis comprises six sections: SECTION A: This section comprises the problem statement, the research purpose statement and objectives, the central theoretical statement, the approach to the research, the research methodology, as well as the limitations and restrictions of the research. Furthermore, key words are defined and an explanation of the research report is provided. The problem statement shows that problems have been experienced for quite some time regarding the way reports are being handled within the child protection system. The result is that children in need of care and protection do not have effective access to the child protection system and they don’t get effective response when their cases are reported. Although the rights, interests and wants of the child in need of care and protection are addressed in existing legislation and policy, there is still a problem with the implementation and enforcement of said legislation and policy. SECTION B: This section comprises four consecutive articles: Article 1: Legislation and policy for reporting within the child protection system of South Africa In this article, Phase 1 (problem analysis and project planning) of the intervention model was used. An analysis was made of the existing legislation and policy regulations currently in use in South Africa during reporting at the child protection system. This was done by means of literature analysis. Article 2: Agents, cases, persons and response during reporting at the child protection system In this article, Phase 2 (information gathering) of the intervention model was used. An analysis was made of the stipulations of current legislation and policy in South Africa regarding agents, cases, persons and response that should be kept in mind when developing an interagency reporting protocol for the child protection system. It was done by means of literature analysis. Article 3: Reporting procedures and protocols from abroad applicable to an inter-agency reporting protocol for the child protection system In this article, Phase 2 (information gathering) of the intervention model was used. The contents of foreign reporting procedures and protocols were analised in an effort to determine what contribution such procedures and protocols can make to the development of an inter-agency reporting protocol for the child protection system. It was done by means of literature analysis. Article 4: An inter-agency reporting protocol for the child protection system in the Free State In this article, Phases 3 (design), 5 (evaluation and advanced development) and 6 (dissemination) of the intervention model were used. The researcher used the information that came to the fore during the literature analysis in Phases 1 and 2 of the intervention model, to design an inter-agency reporting protocol and flow charts for the child protection system in the Free State. The suitability of this protocol was tested by means of semi-structured interviews with the agents responsible for handling reports within the child protection system. The qualitative data obtained from this was used for the further development of an inter-agency reporting protocol for the child protection system in the Free State. SECTION C: This section comprises a summary of the collective findings and conclusions that came to the fore during the research, whereafter recommendations were being made. SECTION D: This section comprises the various appendices used during the research. SECTION E: This section comprises a complete list of references. SECTION F: This section comprises the final inter-agency reporting protocol for the child protection system in the Free State. / PhD (Social Work), North-West University, Potchefstroom Campus, 2014
9

'n Interagentskap-aanmeldingsprotokol vir die kinderbeskermingstelsel in die Vrystaat / Martha Levina van der Schyff

Van der Schyff, Martha Levina January 2014 (has links)
The overall purpose of this research was to develop an inter-agency reporting protocol for the child protection system in the Free State. The aim was to integrate current legislation and policy into this inter-agency reporting protocol to create standardised reporting procedures to ensure effective access to and response from the child protection system for the child in need of care and protection. The thesis comprises six sections: SECTION A: This section comprises the problem statement, the research purpose statement and objectives, the central theoretical statement, the approach to the research, the research methodology, as well as the limitations and restrictions of the research. Furthermore, key words are defined and an explanation of the research report is provided. The problem statement shows that problems have been experienced for quite some time regarding the way reports are being handled within the child protection system. The result is that children in need of care and protection do not have effective access to the child protection system and they don’t get effective response when their cases are reported. Although the rights, interests and wants of the child in need of care and protection are addressed in existing legislation and policy, there is still a problem with the implementation and enforcement of said legislation and policy. SECTION B: This section comprises four consecutive articles: Article 1: Legislation and policy for reporting within the child protection system of South Africa In this article, Phase 1 (problem analysis and project planning) of the intervention model was used. An analysis was made of the existing legislation and policy regulations currently in use in South Africa during reporting at the child protection system. This was done by means of literature analysis. Article 2: Agents, cases, persons and response during reporting at the child protection system In this article, Phase 2 (information gathering) of the intervention model was used. An analysis was made of the stipulations of current legislation and policy in South Africa regarding agents, cases, persons and response that should be kept in mind when developing an interagency reporting protocol for the child protection system. It was done by means of literature analysis. Article 3: Reporting procedures and protocols from abroad applicable to an inter-agency reporting protocol for the child protection system In this article, Phase 2 (information gathering) of the intervention model was used. The contents of foreign reporting procedures and protocols were analised in an effort to determine what contribution such procedures and protocols can make to the development of an inter-agency reporting protocol for the child protection system. It was done by means of literature analysis. Article 4: An inter-agency reporting protocol for the child protection system in the Free State In this article, Phases 3 (design), 5 (evaluation and advanced development) and 6 (dissemination) of the intervention model were used. The researcher used the information that came to the fore during the literature analysis in Phases 1 and 2 of the intervention model, to design an inter-agency reporting protocol and flow charts for the child protection system in the Free State. The suitability of this protocol was tested by means of semi-structured interviews with the agents responsible for handling reports within the child protection system. The qualitative data obtained from this was used for the further development of an inter-agency reporting protocol for the child protection system in the Free State. SECTION C: This section comprises a summary of the collective findings and conclusions that came to the fore during the research, whereafter recommendations were being made. SECTION D: This section comprises the various appendices used during the research. SECTION E: This section comprises a complete list of references. SECTION F: This section comprises the final inter-agency reporting protocol for the child protection system in the Free State. / PhD (Social Work), North-West University, Potchefstroom Campus, 2014
10

Aero-Thermal Characterization Of Silicon Carbide Flexible Tps Using A 30kw Icp Torch

Owens, Walten 01 January 2015 (has links)
Flexible thermal protection systems are of interest due to their necessity for the success of future atmospheric entry vehicles. Current non-ablative flexible designs incorporate a two-dimensional woven fabric on the leading surface of the vehicle. The focus of this research investigation was to characterize the aerothermal performance of silicon carbide fabric using the 30 kW Inductively Coupled Plasma Torch located at the University of Vermont. Experimental results have shown that SiC fabric test coupons achieving surface temperatures between 1000°C and 1500°C formed an amorphous silicon dioxide layer within seconds after insertion into air plasmas. The transient morphological changes that occurred during oxidation caused a time dependence in the gas / surface interactions which may detrimentally affect the in-flight performance. Room temperature tensile tests of the SiC coupons have shown a rapid strength loss for durations less than 240 seconds due to oxidation. Catastrophic failure and temperature spikes were observed on almost all SiC coupons when exposed to air plasmas at heat fluxes above 80 W/cm2. Interestingly, simulation of entry into the Mars atmosphere using a carbon dioxide plasma caused a material response that was vastly different than the predictable silica layer observed during air plasma exposure.

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