Current Search: Mobility (x)
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Title
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Networking and security solutions for VANET initial deployment stage.
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Creator
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Aslam, Baber, Zou, Changchun, Turgut, Damla, Bassiouni, Mostafa, Wang, Chung-Ching, University of Central Florida
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Abstract / Description
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Vehicular ad hoc network (VANET) is a special case of mobile networks, where vehicles equipped with computing/communicating devices (called (")smart vehicles(")) are the mobile wireless nodes. However, the movement pattern of these mobile wireless nodes is no more random, as in case of mobile networks, rather it is restricted to roads and streets. Vehicular networks have hybrid architecture; it is a combination of both infrastructure and infrastructure-less architectures. The direct vehicle...
Show moreVehicular ad hoc network (VANET) is a special case of mobile networks, where vehicles equipped with computing/communicating devices (called (")smart vehicles(")) are the mobile wireless nodes. However, the movement pattern of these mobile wireless nodes is no more random, as in case of mobile networks, rather it is restricted to roads and streets. Vehicular networks have hybrid architecture; it is a combination of both infrastructure and infrastructure-less architectures. The direct vehicle to vehicle (V2V) communication is infrastructure-less or ad hoc in nature. Here the vehicles traveling within communication range of each other form an ad hoc network. On the other hand, the vehicle to infrastructure (V2I) communication has infrastructure architecture where vehicles connect to access points deployed along roads. These access points are known as road side units (RSUs) and vehicles communicate with other vehicles/wired nodes through these RSUs. To provide various services to vehicles, RSUs are generally connected to each other and to the Internet. The direct RSU to RSU communication is also referred as I2I communication. The success of VANET depends on the existence of pervasive roadside infrastructure and sufficient number of smart vehicles. Most VANET applications and services are based on either one or both of these requirements. A fully matured VANET will have pervasive roadside network and enough vehicle density to enable VANET applications. However, the initial deployment stage of VANET will be characterized by the lack of pervasive roadside infrastructure and low market penetration of smart vehicles. It will be economically infeasible to initially install a pervasive and fully networked roadside infrastructure, which could result in the failure of applications and services that depend on V2I or I2I communications. Further, low market penetration means there are insufficient number of smart vehicles to enable V2V communication, which could result in failure of services and applications that depend on V2V communications. Non-availability of pervasive connectivity to certification authorities and dynamic locations of each vehicle will make it difficult and expensive to implement security solutions that are based on some central certificate management authority. Non-availability of pervasive connectivity will also affect the backend connectivity of vehicles to the Internet or the rest of the world. Due to economic considerations, the installation of roadside infrastructure will take a long time and will be incremental thus resulting in a heterogeneous infrastructure with non-consistent capabilities. Similarly, smart vehicles will also have varying degree of capabilities. This will result in failure of applications and services that have very strict requirements on V2I or V2V communications. We have proposed several solutions to overcome the challenges described above that will be faced during the initial deployment stage of VANET. Specifically, we have proposed: 1) a VANET architecture that can provide services with limited number of heterogeneous roadside units and smart vehicles with varying capabilities, 2) a backend connectivity solution that provides connectivity between the Internet and smart vehicles without requiring pervasive roadside infrastructure or large number of smart vehicles, 3) a security architecture that does not depend on pervasive roadside infrastructure or a fully connected V2V network and fulfills all the security requirements, and 4) optimization solutions for placement of a limited number of RSUs within a given area to provide best possible service to smart vehicles. The optimal placement solutions cover both urban areas and highways environments.
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Date Issued
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2012
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Identifier
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CFE0004186, ucf:48993
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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/CFE0004186
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Title
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IMPACT OF GAMMA-IRRADIATION ON THE CHARACTERISTICS OF III-N/GaN BASED HIGH ELECTRON MOBILITY TRANSISTORS.
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Creator
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Yadav, Anupama, Flitsiyan, Elena, Chernyak, Leonid, Peale, Robert, Richie, Samuel, University of Central Florida
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Abstract / Description
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In this study, the fundamental properties of AlGaN/GaN based High Electron Mobility Transistors (HEMTs) have been investigated in order to optimize their performance in radiation harsh environment. AlGaN/GaN HEMTs were irradiated with 60Co gamma-rays to doses up to 1000 Gy, and the effects of irradiation on the devices' transport and optical properties were analyzed. Understanding the radiation affects in HEMTs devices, on carrier transport, recombination rates and traps creation play a...
Show moreIn this study, the fundamental properties of AlGaN/GaN based High Electron Mobility Transistors (HEMTs) have been investigated in order to optimize their performance in radiation harsh environment. AlGaN/GaN HEMTs were irradiated with 60Co gamma-rays to doses up to 1000 Gy, and the effects of irradiation on the devices' transport and optical properties were analyzed. Understanding the radiation affects in HEMTs devices, on carrier transport, recombination rates and traps creation play a significant role in development and design of radiation resistant semiconductor components for different applications. Electrical testing combined with temperature dependent Electron Beam Induced Current (EBIC) that we used in our investigations, provided critical information on defects induced in the material because of gamma-irradiation. It was shown that low dose (below ~250 Gy) and high doses (above ~250 Gy) of gamma-irradiation affects the AlGaN/GaN HEMTs due to different mechanisms. For low doses of gamma-irradiation, the improvement in minority carrier diffusion length is likely associated with the irradiation-induced growing lifetime of the non-equilibrium carriers. However, with the increased dose of irradiation (above ~ 250 Gy), the concentration of point defects, such as nitrogen vacancies, as well as the complexes involving native defects increases which results in the non-equilibrium carrier scattering. The impact of defect scattering is more pronounced at higher radiation, which leads to the degradation in the mobility and therefore the diffusion length. In addition for each device under investigation, the temperature dependent minority carrier diffusion length measurements were carried out. These measurements allowed the extraction of the activation energy for the temperature-induced enhancement of the minority carrier transport, which (activation energy) bears a signature of defect levels involved the carrier recombination process. Comparing the activation energy before and after gamma-irradiation identified the radiation-induced defect levels and their dependences. To complement EBIC measurements, spatially resolved Cathodoluminescence (CL) measurements were carried out at variable temperatures. Similar to the EBIC measurements, CL probing before and after the gamma-irradiation allowed the identification of possible defect levels generated as a result of gamma-bombardment. The observed decrease in the CL peak intensity after gamma-irradiation provides the direct evidence of the decrease in the number of recombination events. Based on the findings, the decay in the near-band-edge intensity after low-dose of gamma-irradiation (below ~250 Gy) was explained as a consequence of increased non-equilibrium carrier lifetime. For high doses (above ~250 Gy), decay in the CL intensity was observed to be related to the reduction in the mobility of charge carriers. The results of EBIC are correlated with the CL measurements in order to demonstrate that same underlying process is responsible for the changes induced by the gamma-irradiation. DC current-voltage measurements were also conducted on the transistors to assess the impact of gamma-irradiation on transfer, gate and drain characteristics. Exposure of AlGaN/GaN HEMTs to high dose of 60Co gamma-irradiation (above ~ 250 Gy) resulted in significant device degradation. Gamma-rays doses up to 1000 Gy are shown to result in positive shift in threshold voltage, a reduction in the drain current and transconductance due to increased trapping of carriers and dispersion of charge. In addition, a significant increase in the gate leakage current was observed in both forward and reverse directions after irradiation. Post-irradiation annealing at relatively low temperature was shown to restore the minority carrier transport as well as the electrical characteristics of the devices. The level of recovery of gamma-irradiated devices after annealing treatment depends on the dose of the irradiation. The devices that show most recovery for a particular annealing temperature are those exposed to the low doses of gamma-irradiation, while those exposed to the highest doses results in no recovery of performance. The latter fact indicates that a higher device annealing temperature is needed for larger doses of gamma-irradiation.
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Date Issued
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2016
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Identifier
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CFE0006424, ucf:51458
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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/CFE0006424
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Title
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GAYME: The development, design and testing of an auto-ethnographic, documentary game about quarely wandering urban/suburban spaces in Central Florida.
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Creator
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Moran, David, Moshell, Jack, Santana, Maria, Kim, Si Jung, McDaniel, Thomas, Vie, Stephanie, Pugh, William, University of Central Florida
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Abstract / Description
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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.
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Date Issued
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2014
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Identifier
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CFE0005214, ucf:50641
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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/CFE0005214
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Title
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The Social Function of For-Profit Higher Education in the United States.
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Creator
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Baird, Andrew, Carter, J. Scott, Carter, Shannon, Gay, David, Roos, J., University of Central Florida
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Abstract / Description
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This study uses the competing Burton Clark's (")Cooling Out Theory(") and Daniel Bell's (")Theory of the Postindustrial Economy(") to examine the function that for-profit colleges and universities (FPCUs) play in American higher education and how it is different from non-profit traditional colleges and universities (TCUs). This was done through three sections of analysis. The first examined if students who enroll at these FPCUs are less academically prepared than those attending non-profit...
Show moreThis study uses the competing Burton Clark's (")Cooling Out Theory(") and Daniel Bell's (")Theory of the Postindustrial Economy(") to examine the function that for-profit colleges and universities (FPCUs) play in American higher education and how it is different from non-profit traditional colleges and universities (TCUs). This was done through three sections of analysis. The first examined if students who enroll at these FPCUs are less academically prepared than those attending non-profit traditional colleges or universities. The second tested if academic preparedness is associated with postsecondary performance at FPCUs to the same degree it is at TCUs. The final section of analysis looked at FPCU graduates to see if they have different short-term job outcomes when compared to traditional college graduates. This research utilizes The Beginning Postsecondary Survey 2009- a restricted-use longitudinal data set produced by the National Center for Education Statistics that followed 16,700 first-time college enrollees from 2003 until 2009. This data set includes information on student demographics, academic performance, enrollment history, and job outcomes. The results of this study indicated that when compared to traditional college students, FPCU students are less likely to be academically prepared for college and are more frequently characterized by risk factors that previous research has shown makes it less likely they will complete their degree. This research also found that unlike TCUs, high school academic performance is not associated with post-secondary performance or likelihood of degree attainment at FPCUs. Finally, it was observed that FPCU graduates were less likely to have jobs related to their degree and earned less income than TCU graduates, but had about the same degree of job satisfaction.
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Date Issued
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2015
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Identifier
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CFE0005761, ucf:50096
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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/CFE0005761
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Title
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SPRAY COOLING FOR LAND, SEA, AIR AND SPACE BASED APPLICATIONS,A FLUID MANAGEMENT SYSTEM FOR MULTIPLE NOZZLE SPRAY COOLING AND A GUIDE TO HIGH HEAT FLUX HEATER DESIGN.
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Creator
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Glassman, Brian, Chow, Louis, University of Central Florida
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Abstract / Description
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This thesis is divided into four distinct chapters all linked by the topic of spray cooling. Chapter one gives a detailed categorization of future and current spray cooling applications, and reviews the major advantages and disadvantages that spray cooling has over other high heat flux cooling techniques. Chapter two outlines the developmental goals of spray cooling, which are to increase the output of a current system and to enable new technologies to be technically feasible. Furthermore,...
Show moreThis thesis is divided into four distinct chapters all linked by the topic of spray cooling. Chapter one gives a detailed categorization of future and current spray cooling applications, and reviews the major advantages and disadvantages that spray cooling has over other high heat flux cooling techniques. Chapter two outlines the developmental goals of spray cooling, which are to increase the output of a current system and to enable new technologies to be technically feasible. Furthermore, this chapter outlines in detail the impact that land, air, sea, and space environments have on the cooling system and what technologies could be enabled in each environment with the aid of spray cooling. In particular, the heat exchanger, condenser and radiator are analyzed in their corresponding environments. Chapter three presents an experimental investigation of a fluid management system for a large area multiple nozzle spray cooler. A fluid management or suction system was used to control the liquid film layer thickness needed for effective heat transfer. An array of sixteen pressure atomized spray nozzles along with an imbedded fluid suction system was constructed. Two surfaces were spray tested one being a clear grooved Plexiglas plate used for visualization and the other being a bottom heated grooved 4.5 x 4.5 cm2 copper plate used to determine the heat flux. The suction system utilized an array of thin copper tubes to extract excess liquid from the cooled surface. Pure water was ejected from two spray nozzle configurations at flow rates of 0.7 L/min to 1 L/min per nozzle. It was found that the fluid management system provided fluid removal efficiencies of 98% with a 4-nozzle array, and 90% with the full 16-nozzle array for the downward spraying orientation. The corresponding heat fluxes for the 16 nozzle configuration were found with and without the aid of the fluid management system. It was found that the fluid management system increased heat fluxes on the average of 30 W/cm2 at similar values of superheat. Unfortunately, the effectiveness of this array at removing heat at full levels of suction is approximately 50% & 40% of a single nozzle at respective 10aC & 15aC values of superheat. The heat transfer data more closely resembled convective pooling boiling. Thus, it was concluded that the poor heat transfer was due to flooding occurring which made the heat transfer mechanism mainly forced convective boiling and not spray cooling. Finally, Chapter four gives a detailed guide for the design and construction of a high heat flux heater for experimental uses where accurate measurements of surface temperatures and heat fluxes are extremely important. The heater designs presented allow for different testing applications; however, an emphasis is placed on heaters designed for use with spray cooling.
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Date Issued
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2005
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Identifier
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CFE0000473, ucf:46351
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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/CFE0000473
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Title
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BRAVE NEW WORLD RELOADED: ADVOCATING FOR BASIC CONSTITUTIONAL SEARCH PROTECTIONS TO APPLY TO CELL PHONES FROM EAVESDROPPING AND TRACKING BY THE GOVERNMENT AND CORPORATE ENTITIES.
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Creator
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Berrios-Ayala, Mark, Milon, Abby, University of Central Florida
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Abstract / Description
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Imagine a world where someone's personal information is constantly compromised, where federal government entities AKA Big Brother always knows what anyone is Googling, who an individual is texting, and their emoticons on Twitter. Government entities have been doing this for years; they never cared if they were breaking the law or their moral compass of human dignity. Every day the Federal government blatantly siphons data with programs from the original ECHELON to the new series like PRISM...
Show moreImagine a world where someone's personal information is constantly compromised, where federal government entities AKA Big Brother always knows what anyone is Googling, who an individual is texting, and their emoticons on Twitter. Government entities have been doing this for years; they never cared if they were breaking the law or their moral compass of human dignity. Every day the Federal government blatantly siphons data with programs from the original ECHELON to the new series like PRISM and Xkeyscore so they can keep their tabs on issues that are none of their business; namely, the personal lives of millions. Our allies are taking note; some are learning our bad habits, from Government Communications Headquarters' (GCHQ) mass shadowing sharing plan to America's Russian inspiration, SORM. Some countries are following the United States' poster child pose of a Brave New World like order of global events. Others like Germany are showing their resolve in their disdain for the rise of tyranny. Soon, these new found surveillance troubles will test the resolve of the American Constitution and its nation's strong love and tradition of liberty. Courts are currently at work to resolve how current concepts of liberty and privacy apply to the current conditions facing the privacy of society. It remains to be determined how liberty will be affected as well; liberty for the United States of America, for the European Union, the Russian Federation and for the people of the World in regards to the extent of privacy in today's blurred privacy expectations.
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Date Issued
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2014
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Identifier
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CFH0004537, ucf:45187
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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/CFH0004537
Pages