11 resultados para Performance of High Energy Physics detectors

em Digital Commons at Florida International University


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Over the past one hundred years, interscholastic athletic programs have evolved to a place of prominence in both public and private education across America. The National Federation of State High School Associations (NFHS) estimates that approximately 3.96 million males and 2.80 million females participated in organized high school athletic programs during the 2001–2002 school year at over 17 thousand public and private high schools. The popularity of interscholastic athletic programs has resulted in continuous investigations of the relationship between high school athletic programs and academic performance. ^ The present study extends earlier investigations by examining the relation of athletic participation to several indicators of academic performance for senior high school students. This research examined: (a) average daily attendance of varsity athletes and non-athletes; (b) final cumulative grade point average; and (c) test scores on the tenth grade Florida Comprehensive Assessment Test (FLAT) in both reading and in mathematics. ^ Data were collected on 2081 randomly selected male and female high school students identified as athletes or non-athletes at ten public senior high schools in the Miami-Dade County Public Schools district. The results of the overall analyses showed a positive and significant relationship between athletic participation and educational performance. On average, athletes were absent fewer days from school per year than non-athletes and athletes earned a significantly higher cumulative grade point average than their non-athlete peers. A significant statistical difference was also found in the tenth grade FCAT test scores in both reading and mathematics for athletes and non-athletes when eighth grade FCAT test scores in reading and mathematics were used as co-variates. Athletes earned significantly higher Grade 10 FCAT test scores in both reading and mathematics than non-athletes. ^ Although cause and effect cannot be inferred from this study, the findings do indicate the potentially beneficial value of athletic programs in public secondary education. The study concluded that Florida high school graduation requirements might seriously consider the role of interscholastic athletic programs as a valid and essential extra-curricular activity. ^

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The purpose of this study was to investigate the common factors and experiences that contribute to the success of high ability Black students enrolled in Frank C. Martin Elementary School, the first school in Florida authorized to offer the International Baccalaureate (IB) Primary Years Programme (PYP). The study further sought to determine ways in which educators and stakeholders assisted in maintaining and in increasing Black students' achievement that motivated and encouraged them to pursue similar programs at the middle and high school levels. ^ Three sources of data were used: (a) individual interviews with fourth and fifth grade high ability Black students using a semi-structured format elicited discussion of their perceptions of the PYP and factors contributing to their success; (b) individual interviews with their fourth and fifth grade teachers elicited discussion of teacher expectations and effective instructional strategies; and (c) a questionnaire asked parents of the participating students their reasons for choosing the PYP, their perceptions of the program, and their own level of involvement in their child's learning. Three separate focus groups gathered further data. ^ The results revealed that the factors contributing to the success of high ability Black elementary school students are consistent with those of students in other racial groups. These are a challenging program, high teacher and parental expectations, strong parental involvement and support, a celebration of culture and diversity in a caring and nurturing environment, and the development and internalization of positive attitudes. ^ Implications for future studies might include a longitudinal study conducted over seven years to trace the achievements of Black students throughout the entire IB Program. ^

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The main goal of this dissertation was to study two- and three-nucleon Short Range Correlations (SRCs) in high energy three-body breakup of 3He nucleus in 3He(e, e'NN) N reaction. SRCs are characterized by quantum fluctuations in nuclei during which constituent nucleons partially overlap with each other. ^ A theoretical framework is developed within the Generalized Eikonal Approximation (GEA) which upgrades existing medium-energy methods that are inapplicable for high momentum and energy transfer reactions. High momentum and energy transfer is required to provide sufficient resolution for probing SRCs. GEA is a covariant theory which is formulated through the effective Feynman diagrammatic rules. It allows self-consistent calculation of single and double re-scatterings amplitudes which are present in three-body breakup processes. The calculations were carried out in detail and the analytical result for the differential cross section of 3He(e, e'NN)N reaction was derived in a form applicable for programming and numerical calculations. The corresponding computer code has been developed and the results of computation were compared to the published experimental data, showing satisfactory agreement for a wide range of values of missing momenta. ^ In addition to the high energy approximation this study exploited the exclusive nature of the process under investigation to gain more information about the SRCs. The description of the exclusive 3He( e, e'NN)N reaction has been done using the formalism of the nuclear decay function, which is a practically unexplored quantity and is related to the conventional spectral function through the integration of the phase space of the recoil nucleons. Detailed investigation showed that the decay function clearly exhibits the main features of two- and three-nucleon correlations. Four highly practical types of SRCs in 3He nucleus were discussed in great detail for different orders of the final state re-interactions using the decay function as an unique identifying tool. ^ The overall conclusion in this dissertation suggests that the investigation of the decay function opens up a completely new venue in studies of short range nuclear properties. ^

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The main goal of this dissertation was to study two- and three-nucleon Short Range Correlations (SRCs) in high energy three-body breakup of 3He nucleus in 3He(e, e'NN)N reaction. SRCs are characterized by quantum fluctuations in nuclei during which constituent nucleons partially overlap with each other. A theoretical framework is developed within the Generalized Eikonal Approximation (GEA) which upgrades existing medium-energy methods that are inapplicable for high momentum and energy transfer reactions. High momentum and energy transfer is required to provide sufficient resolution for probing SRCs. GEA is a covariant theory which is formulated through the effective Feynman diagrammatic rules. It allows self-consistent calculation of single and double re-scatterings amplitudes which are present in three-body breakup processes. The calculations were carried out in detail and the analytical result for the differential cross section of 3He(e, e'NN)Nreaction was derived in a form applicable for programming and numerical calculations. The corresponding computer code has been developed and the results of computation were compared to the published experimental data, showing satisfactory agreement for a wide range of values of missing momenta. In addition to the high energy approximation this study exploited the exclusive nature of the process under investigation to gain more information about the SRCs. The description of the exclusive 3He(e, e'NN)N reaction has been done using the formalism of the nuclear decay function, which is a practically unexplored quantity and is related to the conventional spectral function through the integration of the phase space of the recoil nucleons. Detailed investigation showed that the decay function clearly exhibits the main features of two- and three-nucleon correlations. Four highly practical types of SRCs in 3He nucleus were discussed in great detail for different orders of the final state re-interactions using the decay function as an unique identifying tool. The overall conclusion in this dissertation suggests that the investigation of the decay function opens up a completely new venue in studies of short range nuclear properties.

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Concrete substructures are often subjected to environmental deterioration, such as sulfate and acid attack, which leads to severe damage and causes structure degradation or even failure. In order to improve the durability of concrete, the High Performance Concrete (HPC) has become widely used by partially replacing cement with pozzolanic materials. However, HPC degradation mechanisms in sulfate and acidic environments are not completely understood. It is therefore important to evaluate the performance of the HPC in such conditions and predict concrete service life by establishing degradation models. This study began with a review of available environmental data in the State of Florida. A total of seven bridges have been inspected. Concrete cores were taken from these bridge piles and were subjected for microstructural analysis using Scanning Electron Microscope (SEM). Ettringite is found to be the products of sulfate attack in sulfate and acidic condition. In order to quantitatively analyze concrete deterioration level, an image processing program is designed using Matlab to obtain quantitative data. Crack percentage (Acrack/Asurface) is used to evaluate concrete deterioration. Thereafter, correlation analysis was performed to find the correlation between five related variables and concrete deterioration. Environmental sulfate concentration and bridge age were found to be positively correlated, while environmental pH level was found to be negatively correlated. Besides environmental conditions, concrete property factor was also included in the equation. It was derived from laboratory testing data. Experimental tests were carried out implementing accelerated expansion test under controlled environment. Specimens of eight different mix designs were prepared. The effect of pozzolanic replacement rate was taken into consideration in the empirical equation. And the empirical equation was validated with existing bridges. Results show that the proposed equations compared well with field test results with a maximum deviation of ± 20%. Two examples showing how to use the proposed equations are provided to guide the practical implementation. In conclusion, the proposed approach of relating microcracks to deterioration is a better method than existing diffusion and sorption models since sulfate attack cause cracking in concrete. Imaging technique provided in this study can also be used to quantitatively analyze concrete samples.

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This study compared the performance of students who earned GED credentials in Florida with that of graduates of Florida high schools, when members of both groups enrolled for the first time in fall 1992 at an urban multicultural community college in south Florida. GED's and HSD's were matched on gender, race, age range, placement levels, and enrollment in college preparatory courses (reading, English, mathematics). The paired samples t-test compared course grades, first semester GPA, and total college GPA for the groups and subgroups of matched students at a probability level of .05. The McNemar test compared how many students in each group and subgroup re-enrolled for a second and third term, or ever; how many were placed on special academic status during their college enrollment; and how many graduated within 16 semesters. Differences between groups were found only for placement on probation—with HSD's on probation in significantly higher proportion than GED's. ^ Additional findings among subgroups revealed that male and Caucasian HSD subjects earned higher math grades than their GED counterparts. Male HSD's were more likely than male GED's to return to the college at some point after the first term. However, male HSD's were placed on probation in greater proportion than the GED's with whom they were matched. ^ Female GED's earned higher English grades and higher first semester and cumulative GPA's and returned to the college in greater proportion than their HSD counterparts. Black GED's earned higher first-semester GPA's, re-enrolled in terms 2 and 3 and graduated from the college in higher percentages than Black HSD's. Black HSD's were placed on probation in higher proportion than Black GED's. Lastly, greater percentages of HSD than GED subjects in the lowest age range (16–19) were placed on probation. ^ Results connected to the performance of Black GED subjects are likely to have been affected by the fact that 50% of Black study subjects had been born in Jamaica. The place of the GED in the constellation of methods for earning credit by examination is explored, future implications are discussed, and further study is recommended. ^

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In Taiwan, the college freshmen are recruited graduates of both senior high school and senior vocational school. The Ministry of Education (MOE) of the Republic of China prescribes the standards of curriculum and equipment for schools at all levels and categories. There exists a considerably different curriculum arrangement for senior high schools and vocational high schools in Taiwan at the present time. The present study used a causal-comparative research design to identify the influences of different post-secondary educational background on specialized course performance of college business majors. ^ The students involved in this study were limited to the students of four business-related departments at Tamsui Oxford University College in Taiwan. Students were assigned to comparison groups based on their post-secondary educational background as senior high school graduates and commercial high school graduates. The analysis of this study included a comparison of students' performance on lower level courses and a comparison of students' performance in financial management. The analysis also considered the relationship between the students' performance in financial management and its related prerequisite courses. The Kolb Learning Style Inventory (LSI) survey was administered to categorize subjects' learning styles and to compare the learning styles between the two groups in this study. The applied statistical methods included t-test, correlation, multiple regression, and Chi-square. ^ The findings of this study indicated that there were significant differences between the commercial high school graduates and the senior high school graduates on academic performances in specialized courses but not in general courses. There were no significant differences in learning styles between the two groups. These findings lead to the conclusion that business majors' academic performance in specialized courses were influenced by their post-secondary educational background. ^

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As part of a multi-university research program funded by NSF, a comprehensive experimental and analytical study of seismic behavior of hybrid fiber reinforced polymer (FRP)-concrete column is presented in this dissertation. Experimental investigation includes cyclic tests of six large-scale concrete-filled FRP tube (CFFT) and RC columns followed by monotonic flexural tests, a nondestructive evaluation of damage using ultrasonic pulse velocity in between the two test sets and tension tests of sixty-five FRP coupons. Two analytical models using ANSYS and OpenSees were developed and favorably verified against both cyclic and monotonic flexural tests. The results of the two methods were compared. A parametric study was also carried out to investigate the effect of three main parameters on primary seismic response measures. The responses of typical CFFT columns to three representative earthquake records were also investigated. The study shows that only specimens with carbon FRP cracked, whereas specimens with glass or hybrid FRP did not show any visible cracks throughout cyclic tests. Further monotonic flexural tests showed that carbon specimens both experienced flexural cracks in tension and crumpling in compression. Glass or hybrid specimens, on the other hand, all showed local buckling of FRP tubes. Compared with conventional RC columns, CFFT column possesses higher flexural strength and energy dissipation with an extended plastic hinge region. Among all CFFT columns, the hybrid lay-up demonstrated the highest flexural strength and initial stiffness, mainly because of its high reinforcement index and FRP/concrete stiffness ratio, respectively. Moreover, at the same drift ratio, the hybrid lay-up was also considered as the best in term of energy dissipation. Specimens with glassfiber tubes, on the other hand, exhibited the highest ductility due to better flexibility of glass FRP composites. Furthermore, ductility of CFFTs showed a strong correlation with the rupture strain of FRP. Parametric study further showed that different FRP architecture and rebar types may lead to different failure modes for CFFT columns. Transient analysis of strong ground motions showed that the column with off-axis nonlinear filament-wound glass FRP tube exhibited a superior seismic performance to all other CFFTs. Moreover, higher FRP reinforcement ratios may lead to a brittle system failure, while a well-engineered FRP reinforcement configuration may significantly enhance the seismic performance of CFFT columns.

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As part of a multi-university research program funded by NSF, a comprehensive experimental and analytical study of seismic behavior of hybrid fiber reinforced polymer (FRP)-concrete column is presented in this dissertation. Experimental investigation includes cyclic tests of six large-scale concrete-filled FRP tube (CFFT) and RC columns followed by monotonic flexural tests, a nondestructive evaluation of damage using ultrasonic pulse velocity in between the two test sets and tension tests of sixty-five FRP coupons. Two analytical models using ANSYS and OpenSees were developed and favorably verified against both cyclic and monotonic flexural tests. The results of the two methods were compared. A parametric study was also carried out to investigate the effect of three main parameters on primary seismic response measures. The responses of typical CFFT columns to three representative earthquake records were also investigated. The study shows that only specimens with carbon FRP cracked, whereas specimens with glass or hybrid FRP did not show any visible cracks throughout cyclic tests. Further monotonic flexural tests showed that carbon specimens both experienced flexural cracks in tension and crumpling in compression. Glass or hybrid specimens, on the other hand, all showed local buckling of FRP tubes. Compared with conventional RC columns, CFFT column possesses higher flexural strength and energy dissipation with an extended plastic hinge region. Among all CFFT columns, the hybrid lay-up demonstrated the highest flexural strength and initial stiffness, mainly because of its high reinforcement index and FRP/concrete stiffness ratio, respectively. Moreover, at the same drift ratio, the hybrid lay-up was also considered as the best in term of energy dissipation. Specimens with glassfiber tubes, on the other hand, exhibited the highest ductility due to better flexibility of glass FRP composites. Furthermore, ductility of CFFTs showed a strong correlation with the rupture strain of FRP. Parametric study further showed that different FRP architecture and rebar types may lead to different failure modes for CFFT columns. Transient analysis of strong ground motions showed that the column with off-axis nonlinear filament-wound glass FRP tube exhibited a superior seismic performance to all other CFFTs. Moreover, higher FRP reinforcement ratios may lead to a brittle system failure, while a well-engineered FRP reinforcement configuration may significantly enhance the seismic performance of CFFT columns.

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Existing instrumental techniques must be adaptable to the analysis of novel explosives if science is to keep up with the practices of terrorists and criminals. The focus of this work has been the development of analytical techniques for the analysis of two types of novel explosives: ascorbic acid-based propellants, and improvised mixtures of concentrated hydrogen peroxide/fuel. In recent years, the use of these explosives in improvised explosive devices (IEDs) has increased. It is therefore important to develop methods which permit the identification of the nature of the original explosive from post-blast residues. Ascorbic acid-based propellants are low explosives which employ an ascorbic acid fuel source with a nitrate/perchlorate oxidizer. A method which utilized ion chromatography with indirect photometric detection was optimized for the analysis of intact propellants. Post-burn and post-blast residues if these propellants were analyzed. It was determined that the ascorbic acid fuel and nitrate oxidizer could be detected in intact propellants, as well as in the post-burn and post-blast residues. Degradation products of the nitrate and perchlorate oxidizers were also detected. With a quadrupole time-of-flight mass spectrometer (QToFMS), exact mass measurements are possible. When an HPLC instrument is coupled to a QToFMS, the combination of retention time with accurate mass measurements, mass spectral fragmentation information, and isotopic abundance patterns allows for the unequivocal identification of a target analyte. An optimized HPLC-ESI-QToFMS method was applied to the analysis of ascorbic acid-based propellants. Exact mass measurements were collected for the fuel and oxidizer anions, and their degradation products. Ascorbic acid was detected in the intact samples and half of the propellants subjected to open burning; the intact fuel molecule was not detected in any of the post-blast residue. Two methods were optimized for the analysis of trace levels of hydrogen peroxide: HPLC with fluorescence detection (HPLC-FD), and HPLC with electrochemical detection (HPLC-ED). Both techniques were extremely selective for hydrogen peroxide. Both methods were applied to the analysis of post-blast debris from improvised mixtures of concentrated hydrogen peroxide/fuel; hydrogen peroxide was detected on variety of substrates. Hydrogen peroxide was detected in the post-blast residues of the improvised explosives TATP and HMTD.

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To explore the feasibility of processing Compact Muon Solenoid (CMS) analysis jobs across the wide area network, the FIU CMS Tier-3 center and the Florida CMS Tier-2 center designed a remote data access strategy. A Kerberized Lustre test bed was installed at the Tier-2 with the design to provide storage resources to private-facing worker nodes at the Tier-3. However, the Kerberos security layer is not capable of authenticating resources behind a private network. As a remedy, an xrootd server on a public-facing node at the Tier-3 was installed to export the file system to the private-facing worker nodes. We report the performance of CMS analysis jobs processed by the Tier-3 worker nodes accessing data from a Kerberized Lustre file. The processing performance of this configuration is benchmarked against a direct connection to the Lustre file system, and separately, where the xrootd server is near the Lustre file system.