Stolen Artwork: Deciding Ownership Is No Pretty Picture

This thesis analyzes the power losses in induction machines and how the losses depend on the harmonic content of the applied voltages. Two cases are compared, one case where a machine is fed with a sinusoidial voltage and one case with a modular multilevel converter (M2C). The sine is representing an ideal grid while the M2C represents a case with harmonic content. The usage of converters for electrical drive systems is increasing due to advantages when the rotor speed could be variable by changing the frequency of the voltage. This is usually increasing the efficiency of the overall system, but is also adding harmonics fed to the machine and switching losses in the converter. Low switching losses in the inverter usually create higher harmonic content that instead increases the losses of the machine. The M2C is then proposed as a converter topology that can keep the harmonic content low while keeping the switching losses relatively low. This study focuses on the iron losses, the part of the total losses that is most hard to predict or measure. Today’s methods used to calculate the iron losses are often rough approximations that do not take the impact of the harmonic content of voltage into consideration, even though the iron losses are dependent on the harmonics. Experimental results in the study show that the losses of a M2C-fed case do not differ much from a sine-fed case. The difference could be explained by low increase of iron losses caused by the small harmonic content from the M2C. The increase of iron losses was linked to the harmonic content of the voltage.Detta examensarbete analyserar effektförluster i induktionsmaskiner och hur förlusterna beror på övertonsinnehållet i den matande spänningen. Två fall kommer att jämföras, ett fall där en maskin är matad från en sinus spänning och ett fall med en modulär multinivå omvandlare (M2C). Sinusen representerar ett idealt nät medan M2C representerar ett fall med övertonsinnehåll. Användning av omvandlare för elekriska drivsystem ökar på grund av fördelarna när rotorhastighet kan varieras genom att ändra frekvensen från den matande växelriktaren. Detta ökar vanligtvis verkningsgraden på det sammanlagda systemet, men detta bidrar även med övertonsinnehåll matat till maskinen och switchförluster i omvandlaren. Låga switchförluster i omvandlaren medför oftast ett högt övertonsinnehåll som istället ökar förlusterna i maskinen. M2C är därför föreslaget som en teknik som håller övertonsinnehållet lågt medan switchförlusterna är relativt låga. Denna studie fokuserar på järnförluster, den del av de totala förlusterna som är som svårast att förutse eller mäta. De metoder som finns för att beräkna järnförlusterna är vanligtvis grova skattningar som inte tar hänsyn till inverkan från spänningens övertoninnehåll, även om järnförluster beror på övertonerna i stor utsträckning. Experimentella resultat i studien visar att förlusterna i ett M2C-matat fall inte avviker i stor utsträkning jämte ett sinusmatat fall. Skillnanen kan förklaras utifrån den lilla ökningen av järnförluster från det låga övertonsinnehållet från M2C:n. Järnförlusterna ses vara kopplade till övertonsinnehållet i spänningen

American National Security Strategy as it Pertains to the Afghanistan War

Following 16 years of war in Afghanistan the number of U.S. military, Coalition forces and Afghan civilian fatalities has exceeded the number of Americans lost on 9/11 and has cost the United States nearly $841 billion dollars. The results are that Afghanistan remains in turmoil and that terrorist attacks, the reason for the invasion, continues. The question is should United States assess a different approach that would result in less blood and treasure being spent to address the need to mitigate terrorist threats. Guided by the analysis of conventional- centric and asymmetric-centric approaches to a counterterrorism strategy, this qualitative study focused on evaluating the effects of U.S. national strategy for the Afghanistan war between 2001 and 2016. A narrative inquiry was employed that used extensive in-depth interviews with five implementers and five recipients of the American strategy based in Afghanistan. The participants were recruited from the U.S. Special Forces community that implemented American strategy in Afghanistan, and from Afghans that experienced the American strategy firsthand. Data were analyzed by employing an inductive coding method. The literature review revealed an intention to use large military forces to conduct a conventional-centric counterterrorism strategy, but the narrative inquiry revealed a negative effect of the conventional-centric counterterrorism strategy. Though more research in this area is needed the implications from the findings for positive social change that an asymmetric-centric strategy could offer as a possible effective solution for countering terrorism. These recommendations may help national strategy developers develop a structure to develop future counterterrorism strategies

Ride a Plane, or Ride a Cowboy

Air travel may not be an extremely lucrative business in today\u27s economic climate, but while profits may be down, they can at least take comfort knowing that their advertising work has been done for them. Its difficult to improve upon the subtle link in the American consumer\u27s mind between air travel and exotic vacation ads. A successful ad campaign for a major airline could very well simply be a picture of a beautiful island getaway, and the name of the airline – nothing more. How could this possibly be improved upon? Simple: Sex! One doesn\u27t have to think for too long to conjure up images of brief, cramped encounters in the airline bathrooms. Airlines have been capitalizing on the use of sex in their business for years – images of flight attendants in the late 1970\u27s reveal uniforms that might as well be replaced with bathing suits. However, as working conditions for women improved with time, those uniforms disappeared. Airlines, however, still know that sex sells. They\u27ve simply shifted the sex appeal from in-flight to print ads

Laboratory investigation of a method for determining in situ saturated hydraulic conductivity

A study was conducted to determine the applicability of a method for determining in situ saturated hydraulic conductivity in porous media. This method requires an accurate measurement of the horizontal port water speed through a section of a borehole packed with a porous material of known hydraulic conductivity. Analytical expressions describing the theoretical basis for the method were investigated, as was the sensitivity of these expressions to varied parameters; Experiments were designed and performed in an attempt to determine if the theory could be successfully applied in a laboratory setting. These experiments were conducted in a large flowchamber which simulates a confined, homogeneous and isotropic aquifer, and which allows for precise control of aquifer pore water velocity. Two techniques were examined. The first technique involves measuring the advective component of a heat pulse generated within the borehole porous medium. The second technique involves determining the dilution rate of an electrolytic tracer introduced into the borehole porous medium. For each technique, experimental instruments were designed and constructed, or existing instruments were modified. Theoretical considerations and analytical expressions justifying each technique were developed and investigated

Continuous Tuning and Calibration of Vibratory Gyroscopes

A method of control and operation of an inertial reference unit (IRU) based on vibratory gyroscopes provides for continuously repeated cycles of tuning and calibration. The method is intended especially for application to an IRU containing vibratory gyroscopes that are integral parts of microelectromechanical systems (MEMS) and that have cloverleaf designs, as described in several previous NASA Tech Briefs articles. The method provides for minimization of several measures of spurious gyroscope output, including zero-rate offset (ZRO), angle random walk (ARW), and rate drift. These benefits are afforded both at startup and thereafter during continuing operation, in the presence of unknown rotation rates and changes in temperature. A vibratory gyroscope contains a precision mechanically resonant structure containing two normal modes of vibration nominally degenerate in frequency and strongly coupled via a Coriolis term. In the case of the cloverleaf design MEMS gyro, these normal modes of vibration are plate rocking modes. The rocking motion of the plate is described by giving two angles, theta(sub 1) and theta(sub 2). A proof mass consisting of a post orthogonal to the plate ensures a high degree of Coriolis coupling of vibratory energy from one mode into the other under inertial rotation. The plate is driven and sensed capacitively across a few-microns-wide gap, and the normal mode frequencies can be tuned electrostatically by DC voltages applied across this gap. In order to sense rotation, the resonator plate is caused to rock in the theta(sub 1) direction, then any small motions in the theta(sub 2) direction are sensed, rebalanced, and interpreted as inertial rotation. In this scenario, the "drive" has been assigned to the theta(sub 1) direction, and the "sense" has been assigned to the theta(sub 2) direction

Barrier Layer Impact on Rapid Intensification of Hurricanes (2000-2018) in the Atlantic Ocean

Hurricane prediction is an evolving challenge that has seen much improvement over the years. While hurricane models have improved in predicting the path of storms, forecasts of hurricane intensity are unreliable due to the complexity of environmental data, lack of understanding of how relative humidity, vertical wind shear, hurricane structure and other possible factors affect intensity. Rapid Intensification (RI), which is a wind speed increase of +30 kts over a 24-hr period, can contribute to major destruction and loss of life to coastal communities affected by hurricanes, and is especially difficult to predict. Given the continued development of coastal regions and the threat of RI occurring without warning, it is imperative to better examine all possible factors that might influence hurricane RI to better understand and predict RI. The need for more research into RI was underscored by the devastation caused by rapidly intensifying hurricanes in the Caribbean and the east and gulf coast regions of the U.S. during the 2017 and 2018 hurricane seasons, which included the first landfall of a Category 5 hurricane (Hurricane Michael, 2018) since Hurricane Andrew in 1992. Recent studies examining the barrier layer (BL) of the water column and its relationship to hurricane intensification have shown that BLs favor RI, and that barrier layer thickness (BLT) may influence the storm’s intensity. To determine if BLs might improve the prediction of hurricane intensity, this study examined all hurricanes in the Atlantic Ocean, Caribbean, and Gulf of Mexico spanning the years 2000-2018. Using relevant HYCOM data, daily temperature (T), salinity (S), mixed layer thickness (mlp), isothermal layer thickness (mld), and BLT were examined to determine each factor’s horizontal distribution and possible influence on RI events occurring during the 139 hurricanes. Additional analysis was conducted on 12 randomly selected hurricanes (six of which had RI events and six of which did not) to determine if these factors, specifically BLT, act as significant predictors for RI events. Although no known link has been shown in previous research, this study also sought to determine if there is a correlation between RI and the horizontal variability of BLT and other key factors near the center of a hurricane (within 1 degree lat/lon).Though BLs can exist in any ocean, they are constantly changing and not always present. In this study, however, it was observed that BLs were present during all hurricanes in the Atlantic (2000-2018), whether they experienced a period of RI or not. Using an untested horizontal statistical analysis, this study shows that barrier layer thickness (BLT) does not appear to be a significant predictor of the probability of an RI event to occur, with no clear relationship shown between BLT and the magnitude of intensification, but these results cannot be taken as definitive. Given the limitations of this study, future research on hurricane RI should incorporate all known factors that impact hurricane intensity, testing each using multiple intensity models across all ocean basins

How we got here: Short-scale change in identity labels for trans, cis, and non-binary people in the 2000s

Though understudied in research on language variation and change, the lexicon is a crucial domain for sociopolitical transformations of language. This paper presents a corpus-based sociolinguistic analysis of changes in terms for transgender, cisgender, and non-binary individuals in four online communities on the social media blogging site, LiveJournal.com – one for trans women, one for trans men, one for non-binary people, and another for transgender people in general – that were popular in the 2000s. Using innovative corpus methods that utilize general purpose cloud computing tools, we focus on changes in the popularity of labels for trans, cis, and non-binary people, the factors that impact the variable use of these terms, and what kinds of differences can be observed across the four LiveJournal communities of practice studied. It thereby contributes both to the study of language and identity in trans and queer communities and to the development of methods for studying large datasets of technologically-mediated communication

Lexical Change as Sociopolitical Change in Trans and Cis Identity Labels: New Methods for the Corpus Analysis of Internet Data

This paper uses corpus linguistic methods and general purpose computing tools to explore short-scale lexical change in the identity terminology used in an online community for transgender men and other transmasculine people. It focuses on the rapidly changing landscape of labels for trans people, cis people, and non-binary people in a trans community on LiveJournal.com, which was a popular social media venue among trans people in the 2000s. We consider a number of questions about lexical change, including when currently popular forms (e.g. cisgender, non-binary, transmasculine, etc.) were introduced; the decline of labels that have been problematized (e.g. transgendered, transsexual); and the sociocultural discourses that contextualize and account for these changes. We also describe novel methods for social media data collection, which rely on simple custom software, which we call livecorpus. Livecorpus was built for use with widely-available cloud computing tools, meaning that it is serverless (i.e. does not require the provisioning of the analyst’s own servers) and offers flexible configuration that can be modified as data collection progresses. These methods can be applied to other social media sources that are not pre-formatted in ways that facilitate automated analysis, which in practice means we can reach further back into the history of social media-based language use. While scholars of language variation and change have tended to focus on phonological and morphosyntactic variables in unselfconscious vernacular speech rather than the lexicon, we argue that speakers’ awareness of – and metalinguistic discourses about – lexical choices makes this level of language an ideal site for considering linguistic manifestations of sociopolitical change. Far from an unfortunate exception to the normal, non-conscious process of structural linguistic transformation, these types of intentional interventions into lexical usage must be recognized as a critical component of language change