Browsing by Subject "efficiency"
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Item A quantitative man-machine model for cyber security efficiency analysis(Texas A&M University, 2007-04-25) Jung, Sung-OhThe analysis of security defense processes is of utmost importance in the management of various cyber-security attacks, which are increasing in scope and rapidity. Organizations need to optimize their resources based on a sound understanding of the level of their security defense processes' efficiency and the impact of their investment. Modeling and characterization of the dynamics of cyber security management are essential to risk prediction, damage assessment, and resource allocations. This dissertation addresses the interactions between human factors and information systems. On the basis of the spiral life cycle model of software development processes, we develop a realistic, holistic security attack-defense model - Man-Machine Model (M3), which combines human factors and information systems' (i.e., machine) states under an integrated analytical framework. M3 incorporates man and machine components. The man component is comprised of several variables such as Skill & Knowledge (SKKN) and Teamwork Quality (TWQ). The machine component is composed of variables such as traffic volume and the amount of downtime. M3 enables the analysis of intrusion detection and incident response process efficiency, i.e., security defense team performance. With data analysis, we formulate and test four major research hypotheses based on the data collected during security experiments. Through hypothesis testing, we evaluate regression models to estimate the security defense team performance (i.e. efficiency) at different levels of human intelligence (e.g., skill and knowledge) and teamwork (e.g., teamwork quality). We assess the fitness and significance of the regression models, and verify their assumptions. Based on these results, organizations can hire those who have an appropriate level of skill and knowledge when it concerns investments to increase the level of skill and knowledge of security personnel. They also can attempt to increase the level of skill and knowledge of security personnel.Item Applying the modified quadriform to measure efficiency in Texas public schools(Texas A&M University, 2007-04-25) Stevens, Chad AaronThe purpose of this study was to identify school districts in the state of Texas that would be considered efficient based on the modified quadriform model, and to identify alterable school characteristics most associated with those efficient schools. The researcher used data from the 2003-2004 Texas Academic Excellence Indicator System in this analysis. Texas school districts that had low expenditures with high student output were classified as efficient. There were two stages to the modified quadriform analysis. In stage one the relationship between input and output was evaluated by two separate linear regressions. The input regression modeled total per pupil expenditure for the district regressed against unalterable school characteristics such as total district enrollment, percentage of economically disadvantaged students, percentage of special education students, percentage of minority students, and local tax base value per pupil. In the output regression six different measures of student outcomes were regressed against the same unalterable characteristics. The measures of student achievement used were the percentage of all students passing the math and reading Texas Assessments of Knowledge and Skills, graduation completion rate, percentage of students taking the Scholastic Aptitude Test and the ACT Test, and the mean scores on the Scholastic Aptitude Test and/or ACT Test. Once the efficient school districts were identified using the positive and negative residuals from the regressions, a discriminant analysis was conducted to determine what alterable characteristics had the most significant relationship with the different student outcome measures. Just over 32% of Texas School Districts would be considered efficient in this model, and the number of students per teacher has a significant relationship with the output measures of mean SAT and ACT scores, district completion rate, and Texas Assessment of Knowledge and Skills scores in both math and reading. The data also showed that the percentage of expenditures at central administration was least associated with mean Scholastic Aptitude Test and ACT scores along with district completion rate. This study was intended to be a descriptive ??????bird??????s eye?????? view of efficiency in the Texas system, the researcher believes that this initial study will be a catalyst for more focused research using this production function method of measuring efficiency, and that one day it may lead to an operational definition of efficiency in the Texas system.Item Conversion of MixAlco Process Sludge to Liquid Transportation Fuels(2012-02-15) Teiseh, Eliasu 1973-About 8 tons of dry undigested solid waste is generated by the MixAlco process for every 40 tons of food residue waste fed into the process. This MixAlco process produces liquid fuels and the sludge generated can be further converted into synthesis gas using the process of pyrolysis. The hydrogen component of the product synthesis gas may be separated by pressure swing adsorption and used in the hydrogenation of ketones into fuels and chemicals. The synthesis gas may also be catalytically converted into liquid fuels via the Fischer-Tropsch synthesis process. The auger-type pyrolyzer was operated at a temperature between 630-770 degrees C and at feed rates in the range of 280-374 g/minute. The response surface statistical method was used to obtain the highest syngas composition of 43.9 +/- 3.36 v % H2/33.3 +/- 3.29 v % CO at 740 degrees C. The CH4 concentration was 20.3 +/- 2.99 v %. For every ton of sludge pyrolyzed, 5,990 g H2 (719.3 MJ), 65,000 g CO (660 MJ) and 21,170 g CH4 (1055.4 MJ) were projected to be produced at optimum condition. At all temperatures, the sum of the energies of the products was greater than the electrical energy needed to sustain the process, making it energy neutral. To generate internal H2 for the MixAlco process, a method was developed to efficiently separate H2 using pressure swing adsorption (PSA) from the synthesis gas, with activated carbon and molecular sieve 5A as adsorbents. The H2 can be used to hydrogenate ketones generated from the MixAlco process to more liquid fuels. Breakthrough curves, cycle mass balances and cycle bed productivities (CBP) were used to determine the maximum hydrogen CBP using different adsorbent amounts at a synthesis gas feed rate of 10 standard lpm and pressure of 118 atm. A 99.9 % H2 purity was obtained. After a maximum CBP of 66 % was obtained further increases in % recovery led to a decrease in CBP. The synthesis gas can also be catalytically converted into liquid fuels by the Fischer-Tropsch synthesis (FTS) process. A Co-SiO2/Mo-Pd-Pt-ZSM-5 catalyst with a metal-metal-acid functionality was synthesized with the aim of increasing the selectivity of JP-8 (C10-C17) fuel range. The specific surface areas of the two catalysts were characterized using the BET technique. The electron probe microanalyzer (with WDS and EDS capabilities) was then used to confirm the presence of the applied metals Co, Mo, Pd and Pt on the respective supports. In addition to the gasoline (C4-C12) also produced, the synthesis gas H2:CO ratio was also adjusted to 1.90 for optimum cobalt performance in an enhanced FTS process. At 10 atm (150 psig) and 250 degrees C, the conventional FTS catalyst Co-SiO2 produced fuels rich in hydrocarbons within the gasoline carbon number range. At the same conditions the Co-SiO2-Mo-Pd-Pt/HZSM-5 catalyst increased the selectivity of JP-8. When Co-SiO2/Mo-Pd-Pt-HZSM-5 was used at 13.6 atm (200 psig) and 250 degrees C, a further increase in the selectivity of JP-8 and to some extent diesel was observed. The relative amounts of olefins and n-paraffins decreased with the products distribution shifting more towards the production of isomers.Item Efficiency Improvements with Low Heat Rejection Concepts Applied to Low Temperature Combustion(2014-06-25) Penny, MichaelWith increasingly stringent governmental regulations on engine emissions such as oxides of nitrogen (NO_(X)) and particulate matter (PM), there is a strong motivation to decrease the production and release of these harmful substances from internal combustion engines. Simultaneously, there are on-going efforts to increase fuel efficiency to curb usage of natural resources and emission of carbon. In general, improvements in one of these areas comes at the cost of the other; however, the results of a previous computational study have indicated that emissions can be decreased while simultaneously increasing efficiency through the application of low heat rejection (LHR) techniques to low temperature combustion (LTC). The goal of this study is to experimentally confirm these findings using a light duty, multi-cylinder diesel engine. LTC is realized through high levels of exhaust gas recirculation (EGR) and retarded injection timings while different degrees of LHR are achieved by means of higher coolant temperatures which should serve to decrease the temperature gradients across the cylinder walls. An energy balance is conducted on the engine to ensure the validity of the efficiency findings. By applying LHR techniques to LTC operation, the undesirable side effects of LTC were found to be mitigated. Specifically, the emissions of carbon monoxide (CO) and unburned hydrocarbons (HC) were reduced and the loss in engine efficiency was also diminished. NO_(X) and PM emissions did increase but they remained at acceptably low levels. In addition, the results of the energy balance substantiated these trends by properly accounting for the bulk of the input energy. While the full potential of improvements in LTC were not explored due to current engine limitations, these results point to the viability of further research into LHR-LTC concepts.Item Empirical Essays on the Efficiency of Heterogeneous Good Auction(2010-01-14) Martin, Thomas A., IVA recent pursuit of the auction design literature has been the development of an auction mechanism which performs well in a multi-good setting, when the goods are not substitutes. This work began in earnest with the Federal Communications Commission spectrum license auctions in the early nineties and continues to this day. In a setting in which goods are not substitutes, the value of one good depends nonnegatively on the quantities of other goods that are won. This type of interdependent value structure has proven difficult to account for in auction design. However, the need for mechanisms that account for such a value structure hinges on the magnitude of the interdependence, whose computation is an empirical exercise. I identify a setting in which to perform this computation. I develop an empirical methodology that allows me to recover bidders' value functions in a multi-good auction setting. This methodology allows me to assess the magnitude of any interdependence in the goods? value structure. Since the auction setting that I analyze is a variation of the standard uniform price auction, which has been adapted for a multi-good setting, I am able to measure the benefit of having a direct revelation mechanism. This counterfactual study is performed by maximizing the value of the auction using the recovered bidder value functions. I find evidence that there is an interdependent value structure in the setting. The counterfactual auction finds that the standard uniform price auction, adapted to a multi-good setting, performs poorly in the presence of such a value structure. The setting for this analysis is an auction for financial transmission rights held in Texas in 2002. The auction involved twenty two firms and collected almost $70 million in revenue. This research is the first to empirically assess efficiency in this type of auction setting.Item Energy Recovery Ventilator Membrane Efficiency Testing(2013-05-07) Rees, Jennifer AnneA test setup was designed and built to test energy recovery ventilator membranes. The purpose of this test setup was to measure the heat transfer and water vapor transfer rates through energy recover ventilator membranes and find their effectiveness, with air conditions that resemble residential use. Two test chambers were constructed with different channel heights above the membrane; one was 1mm and the other 2mm. The 2mm setup gave measureable results, but small air leaks in the system of 7.0% and 6.2% left room for error. The 1mm setup also had air leaks but they were smaller than the 2mm setup, with leak rates of 1.0% and 5.1%. The permeance of the membrane was found to be 2.58x10^-5 g/(m2*s*Pa) for the 2mm test chamber and 9.90x10^-54 g/(m2*s*Pa) for the 1mm test chamber.Item Evaluation of Gene Breed Type and Expression of Feed Efficiency Candidate Genes, and Their Associations with Carcass Traits in F2 Nellore-Angus Steers(2011-10-21) Cardin, Jessica MarieSteers produced in Cycle I of the Texas A & M University McGregor Genomics Project (n = 232, F2 Nellore-Angus) were evaluated for carcass composition, visceral organ weights, and model predicted residual consumption (MPRC), a measure of feed efficiency. Hot carcass weight was strongly correlated with liver weight (r = 0.70, P < 0.001) heart weight (r = 0.58, P < 0.001), and viscera weight (r = 0.55, P < 0.001) but not spleen weight (r = -0.01, P = 0.83). Liver, heart and viscera weights were moderately positively correlated with external and kidney pelvic heart fat (KPH), but not with marbling. None of the organ weights were correlated with MPRC. A subset of 54 animals was selected for extreme values of residuals of MPRC after a mixed model analysis that included fixed effects of sire and family nested within sire, and these animals were evaluated for insulin-like growth factor I (IGFI) expression in liver samples collected at harvest through quantitative real time polymerase chain reaction (qRT-PCR). IGFI relative quantity (IGFI RQ) was collected from qRT-PCR and was correlated with liver (r = -0.23, P = 0.09), spleen (r = 0.48, P <0.001) and viscera weight (r = 0.24, P = 0.08), but not any carcass trait or MPRC residual. Gene breed types were determined for 4 candidate genes of feed efficiency: insulin like growth factor-1 (IGF1), leptin (LEP), neuropeptide-Y (NPY) and ghrelin (GHRL). Gene breed types were represented as AA, AN, NA, and NN where A and N denote Angus and Nellore, respectively, and paternal inheritance is listed first. Given that contemporary group significantly influenced most traits (MPRC, all carcass traits, liver weight and viscera weight), effects of gene breed type and contemporary group were evaluated together in analyses. GHRL influenced liver (P = 0.02) and viscera weight (P = 0.02), IGF1 influenced kidney, pelvic, and heart fat (P = 0.05), NPY influenced liver weight (P = 0.03) and hot carcass weight (P = 0.04), and LEP influenced ribeye area (P = 0.05) and hot carcass weight (P = 0.04) with a tendency to influence liver weight (P = 0.06). Alternate heterozygotes for GHRL were statistically different in liver weight and viscera weight where NA was heavier than AN. Alternate heterozygotes for LEP did not differ in ribeye area, hot carcass weight, or liver weight. Alternate heterozygotes for NPY differed in liver weight (NA heavier than AN), but did not differ in hot carcass weight. Carcasses with AA for LEP and NPY were 18 to 19 kg heavier (P < 0.05) than those with NN, with heterozygotes intermediate.Item School District Efficiency as Measured by the Financial Allocation Study of Texas(2013-11-01) Steele, RyanThe purpose of this record of study was to analyze efficiency in Texas public schools through the use of the Financial Allocation Study of Texas (FAST). A quantitative analysis of the FAST was conducted using ordered logistic regressions as a means of determining which factors contribute to the efficiency. Data from the three years of the FAST were used in the analysis. The biggest predictor of efficiency in the FAST was the percent of students who were economically disadvantaged. Additionally, it was found that larger districts are more efficient than smaller districts. Efficient districts spend less overall per pupil in 9 of the 15 functions of spending reported by schools and spend less on a variety of programs, including regular education, special education, and athletics/cocurricular spending. However, it was found that spending in the area of bilingual/ESL increased efficiency. It was also found that districts with high property wealth were less efficient overall and that the student/teacher ratio and teacher experience was negatively correlated with efficiency. The implications of this research include the need for districts wishing to become more efficient to increase the class size of classrooms and focus spending on improving the achievement of economically disadvantaged students. In addition, districts should focus resources on campus level administrators rather than instructional or curriculum specialists.Item Simultaneous Efficiency, NOx, and Smoke Improvements through Diesel/Gasoline Dual-Fuel Operation in a Diesel Engine(2014-08-05) Sun, JiafengDiesel/gasoline dual-fuel combustion uses both gasoline and diesel fuel in diesel engines to exploit their different reactivities. This operation combines the advantages of diesel fuel and gasoline while avoiding their disadvantages, attains spatially stratified low temperature combustion (LTC), and yields very low NOx and PM emissions while maintaining good efficiency. It is promising in solving the problems of conventional LTC through better control of ignition and combustion. The benefits of dual-fuel operation and the potential of using gasoline fumigation to realize these benefits provide the major motivation to this research. This research is aimed at using gasoline fumigation in a medium-duty diesel engine to identify and quantify the influencing factors of diesel/gasoline dual-fuel LTC on engine efficiency and emissions. The factors include gasoline fraction, injection settings, rail pressure, intake pressure, and EGR level. This objective was realized through a series of experimental tests done at 1400 rpm and three loads, including both diesel baseline tests and dual-fuel tests. First, design of experiments and relevant statistical techniques were applied to tests. Twenty-three best models between 6 factors (intake pressure, rail pressure, SOI for diesel baseline tests, SOI for dual-fuel tests, EGR level, and gasoline fraction) and 5 targets (efficiency, NOx, smoke number, HC, and CO) were obtained through regression of test data. Confirmation tests were done based on best models. Generally, the observations are improved NOx and smoke emissions, but unimproved or deteriorated efficiency, HC and CO emissions. The optimization effort makes some achievements, but needs further improvement. The influence of each factor is analyzed. The measures to get better models are explained. Second, parametric studies of gasoline fraction and injection timing were done to find their influence on efficiency and emissions. Efficiency generally decreases slightly as gasoline fraction increases or injection timing is retarded. Generally, increasing gasoline fraction is beneficial for NOx and smoke emissions, but HC and CO emissions deteriorate. An advance in injection timing, however, has the opposite influence. Finally, individual cycle data were analyzed to study cyclic variability (CV) and its influence on dual-fuel efficiency and emissions. Factors causing or influencing CV were identified. The CV in dual-fuel operation is more serious than that in diesel operation, in terms of magnitude. Most of the test data studied do not have strong determinism, and the influence of gasoline addition is small.Item Theoretical study of cyclone design(Texas A&M University, 2005-08-29) Wang, LingjuanTo design a cyclone abatement system for particulate control, it is necessary to accurately estimate cyclone performance. In this cyclone study, new theoretical methods for computing travel distance, numbers of turns and cyclone pressure drop have been developed. The flow pattern and cyclone dimensions determine the travel distance in a cyclone. The number of turns was calculated based on this travel distance. The new theoretical analysis of cyclone pressure drop was tested against measured data at different inlet velocities and gave excellent agreement. The results show that cyclone pressure drop varies with the inlet velocity, but not with cyclone diameter. Particle motion in the cyclone outer vortex was analyzed to establish a force balance differential equation. Barth??s "static particle" theory, particle (with diameter of d50) collection probability is 50% when the forces acting on it are balanced, combined with the force balance equation was applied in the theoretical analyses for the models of cyclone cut-point and collection probability distribution in the cyclone outer vortex. Cyclone cut-points for different dusts were traced from measured cyclone overall collection efficiencies and the theoretical model for calculating cyclone overall efficiency. The cut-point correction models (K) for 1D3D and 2D2D cyclones were developed through regression fit from traced and theoretical cut-points. The regression results indicate that cut-points are more sensitive to mass median diameter (MMD) than to geometric standard deviation (GSD) of PSD. The theoretical overall efficiency model developed in this research can be used for cyclone total efficiency calculation with the corrected d50 and PSD. 1D3D and 2D2D cyclones were tested at Amarillo, Texas (an altitude of 1128 m / 3700 ft), to evaluate the effect of air density on cyclone performance. Two sets of inlet design velocities determined by the different air densities were used for the tests. Experimental results indicate that optimal cyclone design velocities, which are 16 m/s (3200 ft/min) for 1D3D cyclones and 15 m/s (3000 ft/min) for 2D2D cyclones, should be determined based on standard air density. It is important to consider the air density effect on cyclone performance in the design of cyclone abatement systems.