Current Search:  transportation (x)

View All Items

  • CSV Spreadsheet
(81 - 85 of 85)

Pages

Prediction of Optical Properties of Pi-Conjugated Organic Materials for Technological Innovations
Title
Prediction of Optical Properties of Pi-Conjugated Organic Materials for Technological Innovations.
Creator
Nayyar, Iffat, Masunov, Artem, Saha, Haripada, Stolbov, Sergey, Gesquiere, Andre, University of Central Florida
Abstract / Description
Organic ?-conjugated solids are promising candidates for new optoelectronic materials. The large body of evidence points at their advantageous properties such as high charge-carrier mobility, large nonlinear polarizability, mechanical flexibility, simple and low cost fabrication and superior luminescence. They can be used as nonlinear optical (NLO) materials with large two-photon absorption (2PA) and as electronic components capable of generating nonlinear neutral (excitonic) and charged ...
Show moreOrganic ?-conjugated solids are promising candidates for new optoelectronic materials. The large body of evidence points at their advantageous properties such as high charge-carrier mobility, large nonlinear polarizability, mechanical flexibility, simple and low cost fabrication and superior luminescence. They can be used as nonlinear optical (NLO) materials with large two-photon absorption (2PA) and as electronic components capable of generating nonlinear neutral (excitonic) and charged (polaronic) excitations. In this work, we investigate the appropriate theoretical methods used for the (a) prediction of 2PA properties for rational design of organic materials with improved NLO properties, and (b) understanding of the essential electronic excitations controlling the energy-transfer and charge-transport properties in organic optoelectronics. Accurate prediction of these electro-optical properties is helpful for structure-activity relationships useful for technological innovations.In Chapter 1 we emphasize on the potential use of the organic materials for these two applications. The 2PA process is advantageous over one-photon absorption for deep-tissue fluorescence microscopy, photodynamic therapy, microfabrication and optical data storage owing to the three-dimensional spatial selectivity and improved penetration depth in the absorbing or scattering media. The design of the NLO materials with large 2PA cross-sections may reduce the optical damage due to the use of the high intensity laser beams for excitation. The organic molecules also possess self-localized excited states which can decay radiatively or nonradiatively to form excitonic states. This suggests the use of these materials in the electroluminescent devices such as light-emitting diodes and photovoltaic cells through the processes of exciton formation or dissociation, respectively. It is therefore necessary to understand ultrafast relaxation processes required in understanding the interplay between the efficient radiative transfer between the excited states and exciton dissociation into polarons for improving the efficiency of these devices. In Chapter 2, we provide the detailed description of the various theoretical methods applied for the prediction as well as the interpretation of the optical properties of a special class of substituted PPV [poly (p-phenylene vinylene)] oligomers. In Chapter 3, we report the accuracy of different second and third order time dependent density functional theory (TD-DFT) formalisms in prediction of the 2PA spectra compared to the experimental measurements for donor-acceptor PPV derivatives. We recommend a posteriori Tamm-Dancoff approximation method for both qualitative and quantitative analysis of 2PA properties. Whereas, Agren's quadratic response methods lack the double excitations and are not suitable for the qualitative analysis of the state-specific contributions distorting the overall quality of the 2PA predictions. We trace the reasons to the artifactual excited states above the ionization threshold. We also study the effect of the basis set, geometrical constraints and the orbital exchange fraction on the 2PA excitation energies and cross-sections. Higher exchange (BMK and M05-2X) and range-separated (CAM-B3LYP) hybrid functionals are found to yield inaccurate predictions both quantitatively and qualitatively. The failure of the exchange-correlation (XC) functionals with correct asymptotic is traced to the inaccurate transition dipoles between the valence states, where functionals with low HF exchange succeed. In Chapter 4, we test the performance of different semiempirical wavefunction theory methods for the prediction of 2PA properties compared to the DFT results for the same set of molecules. The spectroscopic parameterized (ZINDO/S) method is relatively better than the general purpose parameterized (PM6) method but the accuracy is trailing behind the DFT methods. The poor performances of PM6 and ZINDO/S methods are attributed to the incorrect description of excited-to-excited state transition and 2PA energies, respectively. The different semiempirical parameterizations can at best be used for quantitative analysis of the 2PA properties. The ZINDO/S method combined with different orders of multi-reference configuration interactions provide an improved description of 2PA properties. However, the results are observed to be highly dependent on the specific choice for the active space, order of excitation and reference configurations.In Chapter 5, we present a linear response TD-DFT study to benchmark the ability of existing functional models to describe the extent of self-trapped neutral and charged excitations in PPV and its derivative MEH-PPV considered in their trans-isomeric forms. The electronic excitations in question include the lowest singlet (S1) and triplet (T1†) excitons, positive (P+) and negative (P-) polarons and the lowest triplet (T1) states. Use of the long-range-corrected DFT functional, such as LC-wPBE, is found to be crucial in order to predict the physically correct spatial localization of all the electronic excitations in agreement with experiment. The inclusion of polarizable dielectric environment play an important role for the charged states. The particle-hole symmetry is preserved for both the polymers in trans geometries. These studies indicate two distinct origins leading to self-localization of electronic excitations. Firstly, distortion of molecular geometry may create a spatially localized potential energy well where the state wavefunction self-traps. Secondly, even in the absence of geometric and vibrational dynamics, the excitation may become spatially confined due to energy stabilization caused by polarization effects from surrounding dielectric medium.In Chapter 6, we aim to separate these two fundamental sources of spatial localization. We observe the electronic localization of P+ and P- is determined by the polarization effects of the surrounding media and the character of the DFT functional. In contrast, the self-trapping of the electronic wavefunctions of S1 and T1(T1†) mostly follows their lattice distortions. Geometry relaxation plays an important role in the localization of the S1 and T1† excitons owing to the non-variational construction of the excited state wavefunction. While, mean-field calculated P+, P- and T1 states are always spatially localized even in ground state S0 geometry. Polaron P+ and P- formation is signified by the presence of the localized states for the hole or the electron deep inside the HOMO-LUMO gap of the oligomer as a result of the orbital stabilization at the LC-wPBE level. The broadening of the HOMO-LUMO band gap for the T1 exciton compared to the charged states is associated with the inverted bond length alternation observed at this level. The molecular orbital energetics are investigated to identify the relationships between state localization and the corresponding orbital structure.In Chapter 7, we investigate the effect of various conformational defects of trans and cis nature on the energetics and localization of the charged P+ and P- excitations in PPV and MEH-PPV. We observe that the extent of self-trapping for P+ and P- polarons is highly sensitive on molecular and structural conformations, and distribution of atomic charges within the polymers. The particle-hole symmetry is broken with the introduction of trans defects and inclusion of the polarizable environment in consistent with experiment. The differences in the behavior of PPV and MEH-PPV is rationalized based on their orbital energetics and atomic charge distributions. We show these isomeric defects influence the behavior and drift mobilities of the charge carriers in substituted PPVs.
Show less
Date Issued
2013
Identifier
CFE0005110, ucf:50722
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005110
Molecular Regulators of Post-Golgi VLDL Transport Vesicle (PG-VTV) Biogenesis
Title
Molecular Regulators of Post-Golgi VLDL Transport Vesicle (PG-VTV) Biogenesis.
Creator
Riad, Aladdin, Siddiqi, Shadab, Jewett, Travis, Naser, Saleh, University of Central Florida
Abstract / Description
Amongst its numerous functions, the liver is responsible for the synthesis and secretion of very low-density lipoprotein (VLDL). VLDL particles play the important role of facilitating the transport of lipids within the aqueous environment of the plasma; yet high plasma concentrations of these particles result in the pathogenesis of atherosclerosis, while low VLDL secretion from the liver results in hepatic steatosis. VLDL synthesis in the hepatocyte is completed in the Golgi apparatus, which...
Show moreAmongst its numerous functions, the liver is responsible for the synthesis and secretion of very low-density lipoprotein (VLDL). VLDL particles play the important role of facilitating the transport of lipids within the aqueous environment of the plasma; yet high plasma concentrations of these particles result in the pathogenesis of atherosclerosis, while low VLDL secretion from the liver results in hepatic steatosis. VLDL synthesis in the hepatocyte is completed in the Golgi apparatus, which serves as the final site of VLDL maturation prior to its secretion to the bloodstream. The mechanism by which VLDL's targeted transport to the plasma membrane is facilitated has yet to be identified. Our lab has identified this entity. Our findings suggest that upon maturation, VLDL is directed to the plasma membrane through a novel trafficking vesicle, the Post-Golgi VLDL Transport Vesicle (PG-VTV). PG-VTVs containing [3H] radiolabeled VLDL were generated in a cell-free in vitro budding assay for study. First, the fusogenic capabilities of PG-VTVs were established. Vesicles were capable of fusing with the plasma membrane and delivering the VLDL cargo for secretion in a vectorial manner. The next goal of our study is to characterize key regulatory molecular entities necessary for PG-VTV biosynthesis. A detailed analysis was undertaken to determine the PG-VTV proteome via western blot and two-dimensional difference in gel electrophoresis. The identification of key molecular regulators will potentially offer therapeutic targets to control VLDL secretion to the bloodstream.
Show less
Date Issued
2013
Identifier
CFE0005236, ucf:50602
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005236
OPTIMAL DETOUR PLANNING AROUND BLOCKED CONSTRUCTION ZONES
Title
OPTIMAL DETOUR PLANNING AROUND BLOCKED CONSTRUCTION ZONES.
Creator
Jardaneh , Mutasem, Khalafallah, Ahmed, University of Central Florida
Abstract / Description
Construction zones are traffic way areas where construction, maintenance or utility work is identified by warning signs, signals and indicators, including those on transport devices that mark the beginning and end of construction zones. Construction zones are among the most dangerous work areas, with workers facing workplace safety challenges that often lead to catastrophic injuries or fatalities. In addition, daily commuters are also impacted by construction zone detours that affect their...
Show moreConstruction zones are traffic way areas where construction, maintenance or utility work is identified by warning signs, signals and indicators, including those on transport devices that mark the beginning and end of construction zones. Construction zones are among the most dangerous work areas, with workers facing workplace safety challenges that often lead to catastrophic injuries or fatalities. In addition, daily commuters are also impacted by construction zone detours that affect their safety and daily commute time. These problems represent major challenges to construction planners as they are required to plan vehicle routes around construction zones in such a way that maximizes the safety of construction workers and reduces the impact on daily commuters. This research aims at developing a framework for optimizing the planning of construction detours. The main objectives of the research are to first identify all the decision variables that affect the planning of construction detours and secondly, implement a model based on shortest path formulation to identify the optimal alternatives for construction detours. The ultimate goal of this research is to offer construction planners with the essential guidelines to improve construction safety and reduce construction zone hazards as well as a robust tool for selecting and optimizing construction zone detours.
Show less
Date Issued
2011
Identifier
CFE0003586, ucf:48900
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003586
A framework for interoperability on the United States electric grid infrastructure
Title
A framework for interoperability on the United States electric grid infrastructure.
Creator
Laval, Stuart, Rabelo, Luis, Zheng, Qipeng, Xanthopoulos, Petros, Ajayi, Richard, University of Central Florida
Abstract / Description
Historically, the United States (US) electric grid has been a stable one-way power delivery infrastructure that supplies centrally-generated electricity to its predictably consuming demand. However, the US electric grid is now undergoing a huge transformation from a simple and static system to a complex and dynamic network, which is starting to interconnect intermittent distributed energy resources (DERs), portable electric vehicles (EVs), and load-altering home automation devices, that...
Show moreHistorically, the United States (US) electric grid has been a stable one-way power delivery infrastructure that supplies centrally-generated electricity to its predictably consuming demand. However, the US electric grid is now undergoing a huge transformation from a simple and static system to a complex and dynamic network, which is starting to interconnect intermittent distributed energy resources (DERs), portable electric vehicles (EVs), and load-altering home automation devices, that create bidirectional power flow or stochastic load behavior. In order for this grid of the future to effectively embrace the high penetration of these disruptive and fast-responding digital technologies without compromising its safety, reliability, and affordability, plug-and-play interoperability within the field area network must be enabled between operational technology (OT), information technology (IT), and telecommunication assets in order to seamlessly and securely integrate into the electric utility's operations and planning systems in a modular, flexible, and scalable fashion. This research proposes a potential approach to simplifying the translation and contextualization of operational data on the electric grid without being routed to the utility datacenter for a control decision. This methodology integrates modern software technology from other industries, along with utility industry-standard semantic models, to overcome information siloes and enable interoperability. By leveraging industrial engineering tools, a framework is also developed to help devise a reference architecture and use-case application process that is applied and validated at a US electric utility.
Show less
Date Issued
2015
Identifier
CFE0005647, ucf:50193
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005647
GAYME: The development, design and testing of an auto-ethnographic, documentary game about quarely wandering urban/suburban spaces in Central Florida.
Title
GAYME: The development, design and testing of an auto-ethnographic, documentary game about quarely wandering urban/suburban spaces in Central Florida.
Creator
Moran, David, Moshell, Jack, Santana, Maria, Kim, Si Jung, McDaniel, Thomas, Vie, Stephanie, Pugh, William, University of Central Florida
Abstract / Description
GAYME is a transmedia story-telling world that I have created to conceptually explore the dynamics of queering game design through the development of varying game prototypes. The final iteration of GAYME is @deadquarewalking*. It is a documentary game and a performance art installation that documents a carless, gay/queer/quare man's journey on Halloween to get to and from one of Orlando's most well-known gay clubs - the Parliament House Resort. "The art of cruising" city streets to seek out...
Show moreGAYME is a transmedia story-telling world that I have created to conceptually explore the dynamics of queering game design through the development of varying game prototypes. The final iteration of GAYME is @deadquarewalking*. It is a documentary game and a performance art installation that documents a carless, gay/queer/quare man's journey on Halloween to get to and from one of Orlando's most well-known gay clubs - the Parliament House Resort. "The art of cruising" city streets to seek out queer/quare companionship particularly amongst gay, male culture(s) is well-documented in densely, populated cities like New York, San Francisco and London, but not so much in car-centric, urban environments like Orlando that are less oriented towards pedestrians. Cruising has been and continues to be risky even in pedestrian-friendly cities but in Orlando cruising takes on a whole other dimension of danger. In 2011-2012, The Advocate magazine named Orlando one of the gayest cities in America (Breen, 2012). Transportation for America (2011) also named the Orlando metropolitan region the most dangerous city in the country for pedestrians. Living in Orlando without a car can be deadly as well as a significant barrier to connecting with other people, especially queer/quare people, because of Orlando's car-centric design. In Orlando, cars are sexy. At the same time, the increasing prevalence in gay, male culture(s) of geo-social, mobile phone applications using Global Positioning Systems (GPS) and location aware services, such as Grindr (Grindr, LLC., 2009) and even FourSquare (Crowley and Selvadurai, 2009) and Instagram (Systrom and Krieger, 2010), is shifting the way gay/queer/quare Orlandoans co-create social and sexual networks both online and offline. Urban and sub-urban landscapes have transformed into hybrid "techno-scapes" overlaying "the electronic, the emotional and the social with the geographic and the physical" (Hjorth, 2011). With or without a car, gay men can still geo-socially cruise Orlando's car-centric, street life with mobile devices. As such emerging media has become more pervasive, it has created new opportunities to quarely visualize Orlando's "technoscape" through phone photography and hashtag metadata while also blurring lines between the artist and the curator, the player and the game designer.This project particularly has evolved to employ game design as an exhibition tool for the visualization of geo-social photography through hashtag play. Using hashtags as a game mechanic generates metadata that potentially identifies patterns of play and "ways of seeing" across player experiences as they attempt to make meaning of the images they encounter in the game. @deadquarewalking also demonstrates the potential of game design and geo-social, photo-sharing applications to illuminate new ways of documenting and witnessing the urban landscapes that we both collectively and uniquely inhabit.*In Irish culture, (")quare(") can mean (")very(") or (")extremely(") or it can be a spelling of the rural or Southern pronunciation of the word (")queer.(") Living in the American Southeast, I personally relate more to the term (")quare(") versus (")queer.(") Cultural theorist E. Patrick Johnson (2001) also argues for (")quareness(") as a way to question the subjective bias of whiteness in queer studies that risks discounting the lived experiences and material realities of people of color. Though I do not identify as a person of color and would be categorized as white or European American, (")quareness(") has an important critical application for considering how Orlando's urban design is intersectionally racialized, gendered and classed.
Show less
Date Issued
2014
Identifier
CFE0005214, ucf:50641
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005214

Pages