6 resultados para Frontier and pioneer life

em Digital Commons at Florida International University


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An increase in the demand for the freight shipping in the United States has been predicted for the near future and Longer Combination Vehicles (LCVs), which can carry more loads in each trip, seem like a good solution for the problem. Currently, utilizing LCVs is not permitted in most states of the US and little research has been conducted on the effects of these heavy vehicles on the roads and bridges. In this research, efforts are made to study these effects by comparing the dynamic and fatigue effects of LCVs with more common trucks. Ten Steel and prestressed concrete bridges with span lengths ranging from 30’ to 140’ are designed and modeled using the grid system in MATLAB. Additionally, three more real bridges including two single span simply supported steel bridges and a three span continuous steel bridge are modeled using the same MATLAB code. The equations of motion of three LCVs as well as eight other trucks are derived and these vehicles are subjected to different road surface conditions and bumps on the roads and the designed and real bridges. By forming the bridge equations of motion using the mass, stiffness and damping matrices and considering the interaction between the truck and the bridge, the differential equations are solved using the ODE solver in MATLAB and the results of the forces in tires as well as the deflections and moments in the bridge members are obtained. The results of this study show that for most of the bridges, LCVs result in the smallest values of Dynamic Amplification Factor (DAF) whereas the Single Unit Trucks cause the highest values of DAF when traveling on the bridges. Also in most cases, the values of DAF are observed to be smaller than the 33% threshold suggested by the design code. Additionally, fatigue analysis of the bridges in this study confirms that by replacing the current truck traffic with higher capacity LCVs, in most cases, the remaining fatigue life of the bridge is only slightly decreased which means that taking advantage of these larger vehicles can be a viable option for decision makers.

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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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"Perceptions of Organizational Effectiveness over Organizational Life Cycles" written by Kim S. Cameron and David S. Whetten, posits a theory regarding organizational effectiveness criteria change as firms develop along the life cycle continuum. Induced from observations obtained from a simulation game, the Cameron and Whetten theory is applied in this article to two real organizations, Wendy's and McDonald's, with the intention of demonstrating that this theory is applicable in "real life" situations.

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The purpose of this qualitative case study was to gain an understanding of the phenomenon of academic orientation by seeking the insights into an inner-city Haitian-American middle school student's attitudes and world view toward education and life. A phenomenological approach was used in order to explore the way in which Cindy, a minority student, gives meaning to her lived-experiences in terms of her desire to meet academic expectations and her ability to overcome social adversity and/or other risk factors.^ The study attempted to answer the following two research questions: (1) What provides the focus for Cindy's (the subject's) approach to her school work and/or life? (2) What are the processes that give meaning and direction to academic orientation and life for Cindy? In-depth interviewing was the primary method of data collection. In addition, journal and sketchbook entries and school district records were used and classroom observations made.^ The nature of the study to understand lived-experience facilitated the use of the case study method and a phenomenological method of description. Data analysis was conducted by means of an adapted form of the constant comparative approach. Patterns in the data which emerged were coded and categorized according to underlying generative themes. Phenomenological reflection and analysis were used to grasp the experiential structures of Cindy's experience. The following textural themes were identified and confirmed to be essential themes to Cindy's experience: personal challenge to do her best, personal challenge to want to learn, having a sense of determination, being able to think for self, having a disposition to like self, achieving self-respect through performance, seeing a need to help others, being intrinsically motivated, being an independent learner, attending more to academic pressure and less to peer pressure, having motivational catalysts in her life, learning and support opportunities, and having a self-culture. Using Mahrer's humanistic theory of experiencing, Cindy's development was interpreted in terms of her progression through a sequence of developmental plateaus: externalized self, internalized self, and integrating and actualizing self.^ The findings of this study were that Cindy's desire to meet academic expectations is guided by a meaning construction internal frame of reference. High expectations of self in conjunction with other protective factors found in Cindy's home and school environments were also found to be linked to her educational resilience and success. Cindy's lived-experiences were also found to be related to Mahrer's theory of human development. In addition, it was concluded that "minority" students do not all fit into social categories and labels. ^

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The purpose of the present study is to extend our current understanding of the effects of caregiver burden on life satisfaction by examining whether or not there are ethnic differences in coping strategies used to manage caregiving. Several specific hypotheses were tested in order to determine the linkages among age, gender, ethnicity (i.e., familism, filial piety), caregiver burden, coping with caregiving, and life satisfaction. A total of 103 Hispanic and Non-Hispanic White participants ages 60 and older were included in this study (mean age was 67.42; 16.5% male; 83.5 % female; 52.4% Hispanic; 47.6% Non-Hispanic White). The results suggest that demographics and certain coping skills can influence levels of life satisfaction and burden experienced by caregivers. The findings from this study shed light on how to structure effective psychoeducational interventions, facilitate adaptive coping, reduce burden, and improve life satisfaction for older adult caregivers.