Current Search: earth (x)
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Title
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THE INFLUENCE OF GRAPHIC ORGANIZERS ON STUDENTS' ABILITY TO SUMMARIZE AND COMPREHEND SCIENCE CONTENT REGARDING THE EARTH'S CHANGING SURFACE.
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Creator
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Goss, Patricia, Ortiz, Enrique, University of Central Florida
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Abstract / Description
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The purpose of this action research project was to determine how my practice of using graphic organizers during instruction influenced my students' ability to summarize and comprehend significant fifth grade Earth Science content regarding the Earth's changing surface. A secondary purpose was to determine the students' perceptions of how concept mapping assisted in making connections to understand the fifth grade Earth Science content regarding the Earth's changing surface....
Show moreThe purpose of this action research project was to determine how my practice of using graphic organizers during instruction influenced my students' ability to summarize and comprehend significant fifth grade Earth Science content regarding the Earth's changing surface. A secondary purpose was to determine the students' perceptions of how concept mapping assisted in making connections to understand the fifth grade Earth Science content regarding the Earth's changing surface. The three processes used to collect data for this research were concept maps, focus groups and the pre- and post-test results. The themes that emerged were the ability to describe, categorize and classify details, the increased accuracy of the use of vocabulary and the memory of the concepts that students' ability to recall information and understand the Earth Science concepts as evidenced through summarization and comprehension through the pre- and post-test.
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Date Issued
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2009
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Identifier
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CFE0002595, ucf:48287
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002595
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Title
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Creation and Application of Routines for Determining Physical Properties of Asteroids and Exoplanets from Low Signal-To-Noise Data Sets.
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Creator
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Lust, Nathaniel, Britt, Daniel, Fernandez, Yan, Pensky, Marianna, Harris, Alan, University of Central Florida
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Abstract / Description
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Astronomy is a data heavy field driven by observations of remote sources reflecting or emitting light. These signals are transient in nature, which makes it very important to fully utilize every observation. This however is often difficult due to the faintness of these observations, often are only slightly above the level of observational noise. We present new or adapted methodologies for dealing with these low signal-to-noise scenarios, along with practical examples including determining...
Show moreAstronomy is a data heavy field driven by observations of remote sources reflecting or emitting light. These signals are transient in nature, which makes it very important to fully utilize every observation. This however is often difficult due to the faintness of these observations, often are only slightly above the level of observational noise. We present new or adapted methodologies for dealing with these low signal-to-noise scenarios, along with practical examples including determining exoplanet physical properties, periodicities in asteroids, and the rotational and orbital properties of the multiple asteroid system 2577 Litva.
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Date Issued
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2014
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Identifier
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CFE0005523, ucf:50307
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0005523
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Title
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COLLEGE STUDENTS' ATTITUDES TOWARDS GREEN HOTEL PRACTICES.
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Creator
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Perez, Elvis, Kaufman, Tammie, University of Central Florida
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Abstract / Description
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This research was conducted to discover college students' attitude towards green hotel practices and will be helpful to the hospitality industry to help focus their marketing efforts Based on the survey correlations between variables it appears that the people who use green practices at home are more aware of green practices when staying at a hotels. Implementing green practices into hotels will help the environment and also create a positive brand image and loyalty from guests. The movement...
Show moreThis research was conducted to discover college students' attitude towards green hotel practices and will be helpful to the hospitality industry to help focus their marketing efforts Based on the survey correlations between variables it appears that the people who use green practices at home are more aware of green practices when staying at a hotels. Implementing green practices into hotels will help the environment and also create a positive brand image and loyalty from guests. The movement of "Green" benefits everyone: the employer, the employees, and the guests.
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Date Issued
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2013
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Identifier
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CFH0004424, ucf:45100
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFH0004424
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Title
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TO BE MAGIC: THE ART OF ANA MENDIETA THROUGH AND ECOFEMINIST LENS.
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Creator
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Baker, Elizabeth Ann, Mendoza, Ilenia Colon, University of Central Florida
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Abstract / Description
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Ana Mendieta was a Cuban-born American artist whose unique body of work incorporated performance, activism, Earth art, installation, and the Afro-Cuban practices of Santer�a. She began her career at the University of Iowa, were she initially received her degree in painting in 1969. It was not until 1972 that Mendieta shifted radically to performance art. Though she was raised Catholic, she developed an interest in the rituals involved with Santer�a, a culturally predominant Cuban religion,...
Show moreAna Mendieta was a Cuban-born American artist whose unique body of work incorporated performance, activism, Earth art, installation, and the Afro-Cuban practices of Santer�a. She began her career at the University of Iowa, were she initially received her degree in painting in 1969. It was not until 1972 that Mendieta shifted radically to performance art. Though she was raised Catholic, she developed an interest in the rituals involved with Santer�a, a culturally predominant Cuban religion, and it deeply influenced her work in her choice of materials and settings. Santer�a is one of the major faith-based lifestyles of Cuba and is characterized by a synthesis of Afro-Cuban and Catholic characteristics, along with its own unique teachings and rituals. Also a prominent theme in Mendieta�s work was her sense of displacement and her insatiable desire to reconcile her Cuban heritage, which she attempts to resolve, not only through her art, but also during several trips to Cuba. Greater still in its contribution of influence to Mendieta�s work was the ecofeminist movement which amalgamated elements of the feminist and environmental movements; Ecofeminism�s emergence in the United States coincided with the rise of Mendieta�s career during the 1970�s. The movement focused on the correlation between the oppression, degradation, and exploitation of women and the oppression, degradation, and exploitation of the Earth. This thesis examines the life of Ana Mendieta and analyzes how her works may be viewed in an ecofeminist context. It analyzes how Mendieta�s work acts as a reflection of her cultural, social, and political reality and discusses ways in which characteristics of Santer�a and ecofeminism as a discourse influenced the imagery and symbolism used in Mendieta�s artwork throughout her brief career. Formal analysis of Mendieta�s artwork and contextual and historical analysis of Mendieta�s life, the ecofeminist discourse, and Afro-Cuban spirituality are explored in this research.
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Date Issued
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2016
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Identifier
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CFH2000003, ucf:45571
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFH2000003
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Title
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UP-CONVERSION IN RARE-EARTH DOPED MICRO-PARTICLES APPLIED TO NEW EMISSIVE 2D DISLAYS.
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Creator
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Milliez, Anne, Bass, Michael, University of Central Florida
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Abstract / Description
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Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most...
Show moreUp-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most appealing characteristics for displays are: a wide color gamut with very saturated colors, very high brightness operation without damage to the emitters, long lifetimes and efficiencies comparable to those of existing technologies. Other advantages include simplicity of fabrication, versatility of operating modes, and the potential for greatly reduced display weight and depth. Thanks to recent advances in material science and diode laser technology at the excitation wavelength, UC selected materials can be very efficient visible emitters. However, optimal UC efficiencies strongly depend on chosing proper operating conditions. In this thesis, we studied the conditions required for optimization. We demonstrated that high efficiency UC depends on high pump irradiance, low temperature and low scattering. With this understanding we can predict how to optimally use UC emitters in a wide range of applications. In particular, we showed how our very efficient UC emitters can be applied to make full color displays and very efficient white light sources.
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Date Issued
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2006
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Identifier
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CFE0001058, ucf:46828
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001058
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Title
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Investigating compositional variations of S-complex near-Earth asteroids: (1627) Ivar.
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Creator
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Jones, Jenna, Fernandez, Yan, Britt, Daniel, Campins, Humberto, Howell, Ellen, University of Central Florida
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Abstract / Description
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We seek to investigate the complexity and heterogeneity of the surfaces of near-Earth asteroids (NEAs). In particular, we are studying the S-complex NEAs, which account for a large portion of the observed near-Earth objects. Here we present our results for (1627) Ivar, an Amor class NEA with taxonomic type Sqw. In 2013, Ivar's large size and close approach to Earth (minimum distance 0.32 AU) provided an opportunity to observe the asteroid over many different viewing angles for an extended...
Show moreWe seek to investigate the complexity and heterogeneity of the surfaces of near-Earth asteroids (NEAs). In particular, we are studying the S-complex NEAs, which account for a large portion of the observed near-Earth objects. Here we present our results for (1627) Ivar, an Amor class NEA with taxonomic type Sqw. In 2013, Ivar's large size and close approach to Earth (minimum distance 0.32 AU) provided an opportunity to observe the asteroid over many different viewing angles for an extended period of time. We collected delay-Doppler radar images and Doppler spectra using the Arecibo Observatory's 2380 MHz radar, and, by incorporating an extensive lightcurve collection, we have constrained the shape and spin state. In addition, we observed Ivar using NASA's IRTF's SpeX mode to gather rotationally resolved reflected and thermal spectra in the near-IR regime. We have created a high-resolution shape model, and we have found Ivar to have a sidereal period of 4.7951689 (&)#177; 0.0000026 hours with a pole at ecliptic longitude and latitude 336(&)deg;, +37(&)deg; ((&)#177; 6(&)deg;) respectively. We also show that Ivar is more elongated than previous studies suggests, with dimensions along the principal axis 15.15 x 6.25 x 5.66 (&)#177; 10%. This model has been incorporated into our thermal modeling code, SHERMAN, in order to determine which reflective, thermal, and surface properties best reproduce our numerous and rotationally resolved spectra. Primarily, we vary thermal inertia, geometric albedo, and crater fraction (surface roughness) although SHERMAN has many parameters that are allowed to vary. Our findings show that Ivar's thermal observations cannot be reproduced with a homogeneous model, but rather a heterogeneous model with a thermal inertia spot, and possibly different crater fraction values, needs to be applied in order to reproduce all of the spectra. Due to the variations in observing geometry for our thermal spectra, the properties of this spot are well constrained. We find that, with this spot, that the values of thermal inertia, geometric albedo, and crater fraction are 80 (&)#177; 20 J m-2 s-1/2 K-1, 0 (-) 0.3, and 0.27 (&)#177; 0.02, respectively. This work shows the advantage of having many datasets for deep study of an individual NEA, and with these results, we will learn more about the detailed regolith and surface properties of Ivar and how those properties compare to those of other NEAs.
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Date Issued
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2018
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Identifier
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CFE0007022, ucf:52044
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007022
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Title
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Seepage and Stability Analysis of the Earth Dams under Drawdown Conditions by using the Finite Element Method.
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Creator
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Al-Labban, Salama, Chopra, Manoj, Mackie, Kevin, Wang, Dingbao, Elshennawy, Ahmad, University of Central Florida
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Abstract / Description
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One of the major concerns in the behavior of an earth dam is the change in the exit gradient and the impact on the slope stability under drawdown conditions. Drawdown can cause increased seepage forces on the upstream slope which may result in the movement of soil particles in the flow direction and cause erosion problems. In this research, a numerical approach, based on the finite element method (FEM) is used to analyze the seepage through the dam and its foundation to study exit gradients...
Show moreOne of the major concerns in the behavior of an earth dam is the change in the exit gradient and the impact on the slope stability under drawdown conditions. Drawdown can cause increased seepage forces on the upstream slope which may result in the movement of soil particles in the flow direction and cause erosion problems. In this research, a numerical approach, based on the finite element method (FEM) is used to analyze the seepage through the dam and its foundation to study exit gradients and slope stability under both steady-state and transient conditions. The results show that a central core is important in reducing the flux through the dam. Constructing a cutoff under the core further increases the efficiency of the core and lowers the phreatic line. However, it is seen that the submerged weight increases when the earth dam with a core or with a complete cutoff which causes higher water flux to flow out of the dam under the drawdown condition. The exit gradient at the upstream slope may reach critical levels and cause failure of the dam due to erosion. Adding an upstream filter is studied as a possible solution to this problem. Two configurations of the filters are modeled and the slope filter configuration performed best in reducing the exit gradient at the upstream face. A low permeability core with a cutoff increases deformation of the soil because of increased saturated areas in the upstream region. The factor of safety of the slope is also reduced because of the increased buoyancy of the soil at the upstream side of the dam. The soil properties of the upstream filter have a significant influence on the slope stability against sliding. An upstream slope filter increases the stability of the slope while a central filter decreases it.
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Date Issued
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2018
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Identifier
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CFE0007303, ucf:52167
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007303
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Title
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Picosecond Yb-Doped Fiber Amplifier.
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Creator
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Zhu, Weibin, Amezcua Correa, Rodrigo, Schulzgen, Axel, Fathpour, Sasan, University of Central Florida
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Abstract / Description
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Due to its versatility, rare earth doped fiber amplifier (RDFA) has attracted a lot of researchers worldwide in recent years. Depends on different kinds of rare earth ion, RDFA can be categorized into neodymium doped fiber amplifier (NDFA), erbium doped fiber amplifier (EDFA), thulium doped fiber amplifier (TDFA), and so forth. Among many kinds of RDFA, the ytterbium doped fiber amplifier (YDFA) has received even more interest, especially in high power application, mainly because of its broad...
Show moreDue to its versatility, rare earth doped fiber amplifier (RDFA) has attracted a lot of researchers worldwide in recent years. Depends on different kinds of rare earth ion, RDFA can be categorized into neodymium doped fiber amplifier (NDFA), erbium doped fiber amplifier (EDFA), thulium doped fiber amplifier (TDFA), and so forth. Among many kinds of RDFA, the ytterbium doped fiber amplifier (YDFA) has received even more interest, especially in high power application, mainly because of its broad gain bandwidth and high conversion efficiency which are due to its relatively simple electronic structure.The purpose of this research is to study the YDFA by developing a model and building a YDFA setup in free space configuration. The active fiber used in the setup is a few modes, polarization-maintaining double-cladding ytterbium-doped large mode area (LMA) fiber and the length is 1m. The pump used is a tunable 975nm laser diode and a 1064nm laser diode was used as the seed which has 630 ps pulse duration time and 9.59 kHz repetition rate. This setup produces 2.514W average power, corresponding to a pulse peak power of 423kW, with 15W absorbed pump power. The spectrum of the output power has also been investigated.
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Date Issued
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2017
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Identifier
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CFE0006678, ucf:51214
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0006678
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Title
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Design, Synthesis, Stability, and Photocatalytic Studies of Sustainable Metal-Organic Frameworks.
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Creator
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Logan, Matthew, Uribe Romo, Fernando, Zhai, Lei, Yuan, Yu, Kuebler, Stephen, Rahman, Talat, University of Central Florida
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Abstract / Description
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The presented dissertation focuses on the design, synthesis, and characterization of metal-organic frameworks (MOFs) composed of earth-abundant elements the exhibit photoredox activity and studied their application as heterogeneous photocatalysts in organic synthesis and in solar-to-chemical energy conversion. In particular, the structure-property relationships of titanium-based MOFs relating the structure of the organic building unit and the photophysical and photochemical activity of the...
Show moreThe presented dissertation focuses on the design, synthesis, and characterization of metal-organic frameworks (MOFs) composed of earth-abundant elements the exhibit photoredox activity and studied their application as heterogeneous photocatalysts in organic synthesis and in solar-to-chemical energy conversion. In particular, the structure-property relationships of titanium-based MOFs relating the structure of the organic building unit and the photophysical and photochemical activity of the solid material is studied. The first novel family of seven MOFs isoreticular to MIL-125-NH2, includes functionalized with N-alkyl groups with increasing chain length (methyl to heptyl) and with varying connectivity (primary or secondary). The functionalized materials displayed reduced optical bandgaps correlated with the increased inductive donor ability of the alkyl substituents, enhanced excited-state lifetimes, mechanistic information towards visible light CO2 reduction, and improved water stability. The second family of titanium MOFs was prepared with a new secondary building unit and organic links of varying lengths, for which Their crystal structure was solved utilizing powder X-ray diffraction crystallography. This work provides guidelines for the next generation of photocatalyst for the conversion of solar-to-chemical energy and other organic transformations.
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Date Issued
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2018
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Identifier
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CFE0007219, ucf:52217
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007219
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Title
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The Influence of Alloying Additions on Diffusion and Strengthening of Magnesium.
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Creator
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Kammerer, Catherine, Sohn, Yongho, Coffey, Kevin, Challapalli, Suryanarayana, Gordon, Ali, University of Central Florida
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Abstract / Description
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Magnesium alloys are being developed as advanced materials for structural applications where reduced weight is a primary motivator. Alloying can enhance the properties of magnesium without significantly affecting its density. Essential to alloy development, inclusive of processing parameters, is knowledge of thermodynamic, kinetic, and mechanical behavior of the alloy and its constituents. Appreciable progress has been made through conventional development processes, but to accelerate...
Show moreMagnesium alloys are being developed as advanced materials for structural applications where reduced weight is a primary motivator. Alloying can enhance the properties of magnesium without significantly affecting its density. Essential to alloy development, inclusive of processing parameters, is knowledge of thermodynamic, kinetic, and mechanical behavior of the alloy and its constituents. Appreciable progress has been made through conventional development processes, but to accelerate development of suitable wrought Mg alloys, an integrated Materials Genomic approach must be taken where thermodynamics and diffusion kinetic parameters form the basis of alloy design, process development, and properties-driven applications.The objective of this research effort is twofold: first, to codify the relationship between diffusion behavior, crystal structure, and mechanical properties; second, to provide fundamental data for the purpose of wrought Mg alloy development. Together, the principal deliverable of this work is an advanced understanding of Mg systems. To that end, the objective is accomplished through an aggregate of studies. The solid-to-solid diffusion bonding technique is used to fabricate combinatorial samples of Mg-Al-Zn ternary and Mg-Al, Mg-Zn, Mg-Y, Mg-Gd, and Mg-Nd binary systems. The combinatorial samples are subjected to structural and compositional characterization via Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy, Electron Probe Microanalysis, and analytical Transmission Electron Microscopy. Interdiffusion in binary Mg systems is determined by Sauer-Freise and Boltzmann-Matano methods. Kirkaldy's extension of the Boltzmann-Matano method, on the basis of Onsager's formalism, is employed to quantify the main- and cross-interdiffusion coefficients in ternary Mg solid solutions. Impurity diffusion coefficients are determined by way of the Hall method. The intermetallic compounds and solid solutions formed during diffusion bonding of the combinatorial samples are subjected to nanoindentation tests, and the nominal and compositionally dependent mechanical properties are extracted by the Oliver-Pharr method.In addition to bolstering the scantly available experimental data and first-principles computations, this work delivers several original contributions to the state of Mg alloy knowledge. The influence of Zn concentration on Al impurity diffusion in binary Mg(Zn) solid solution is quantified to impact both the pre-exponential factor and activation energy. The main- and cross-interdiffusion coefficients in the ternary Mg solid solution of Mg-Al-Zn are reported wherein the interdiffusion of Zn is shown to strongly influence the interdiffusion of Mg and Al. A critical examination of rare earth element additions to Mg is reported, and a new phase in thermodynamic equilibrium with Mg-solid solution is identified in the Mg-Gd binary system. It is also demonstrated that Mg atoms move faster than Y atoms. For the first time the mechanical properties of intermetallic compounds in several binary Mg systems are quantified in terms of hardness and elastic modulus, and the influence of solute concentration on solid solution strengthening in binary Mg alloys is reported. The most significant and efficient solid solution strengthening is achieved by alloying Mg with Gd. The Mg-Nd and Mg-Gd intermetallic compounds exhibited better room temperature creep resistance than intermetallic compounds of Mg-Al. The correlation between the concentration dependence of mechanical properties and atomic diffusion is deliberated in terms of electronic nature of the atomic structure.
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Date Issued
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2015
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Identifier
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CFE0005815, ucf:50043
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0005815