The job of an air traffic controller is stressful by nature. Conditions like aircraft congestion in the skies, an outdated air traffic system and understaffing at control centers can add to the daily stresses of controllers and often cause fatigue. These conditions describe the current status of Air Traffic Services (ATS) in the United States. If left unaddressed, they could compromise safety, the primary objective of air traffic control. The purpose of this thesis is to assess the regulatory framework surrounding ATS specifically in the area of Safety Management Systems (SMS) and Human Factors and determine the course of action to be taken to improve safety in air traffic control. / This thesis begins with a description of what air traffic controllers do and the issues that ATS face in the U.S. It then examines the regulatory framework of the International Civil Aviation Organization (ICAO) and the U.S. regarding ATS, specifically SMS and Human Factors. A comparison is made between the privatized air traffic system of Canada and the government owned air traffic system of the U.S. and how privatization makes a difference economically, politically and legally when implementing standards and regulations and enforcing them. Finally, suggestions are made in order to improve the legal framework of air traffic services in the U.S.

Made available in DSpace on 2014-12-17T14:55:57Z (GMT). No. of bitstreams: 1 FranciscoGFJ.pdf: 2262425 bytes, checksum: 03d70ce4ca2d284516ec0c9c15922fbf (MD5) Previous issue date: 2006-02-17 / The present work has as objective to present a method of project and implementation of controllers PID, based on industrial instrumentation. An automatic system of auto-tunning of controllers PID will be presented, for systems of first and second order. The software presented in this work is applied in controlled plants by PID controllers implemented in a CLP. Software is applied to make the auto-tunning of the parameters of controller PID of plants that need this tunning. Software presents two stages, the first one is the stage of identification of the system using the least square recursive algorithm and the second is the stage of project of the parameters of controller PID using the root locus algorithm. An important fact of this work is the use of industrial instrumentation for the accomplishment of the experiments. The experiments had been carried through in controlled real plants for controllers PID implemented in the CLP. Thus has not only one resulted obtained with theoreticians experiments made with computational programs, and yes resulted obtained of real systems. The experiments had shown good results gotten with developed software / O presente trabalho tem como objetivo apresentar um m?todo de projeto e implementa??o de controladores PID, baseado em instrumenta??o industrial. Ser? apresentado um sistema autom?tico de re-sintonia de controladores PID, para sistemas de primeira e segunda ordem. O software apresentado neste trabalho ? aplicado em plantas controladas por controladores PID implementados num CLP. O software ? aplicado para fazer a auto-sintonia dos par?metros do controlador PID de plantas que necessitem desta sintonia. O software apresenta duas etapas, a primeira ? a etapa de identifica??o do sistema utilizando o algoritmo dos m?nimos quadrados recursivos e a segunda ? a etapa de projeto dos par?metros do controlador PID utilizando o algoritmo do m?todo do lugar das ra?zes. Um fato importante deste trabalho ? a utiliza??o de instrumenta??o industrial para a realiza??o dos experimentos. Os experimentos foram realizados em plantas reais controladas por controladores PID implementados em um CLP. Assim n?o se tem apenas resultados te?ricos obtidos de experimentos feitos com programas computacionais, e sim resultados obtidos de sistemas reais. Os experimentos mostraram bons resultados obtidos com o software desenvolvido

Evidências empíricas contábeis não só destacam o papel do controller nas empresas, como também salientam situações organizacionais que criam tensões como conflito e ambiguidade de função. Nesse contexto, esta pesquisa tem como objetivo identificar com que intensidade o conflito e ambiguidade de função percebida pelos controllers brasileiros incidem sobre a satisfação no trabalho. A amostra foi composta por 114 controllers das maiores empresas do Brasil segundo a base de dados da revista M&M. A coleta dos dados foi viabilizada por meio de questionário online. O instrumento utilizado para a mensuração das variáveis conflito e ambiguidade de função foi o desenvolvido por Rizzo et al (1970), e, para satisfação no trabalho, foi utilizado Job Satisfaction Index apresentado no trabalho de Tarrant (2008). Para a análise dos dados, foi utilizada a técnica de modelagem de equações estruturais (SEM-PLS) bem como estatísticas descritivas. Não foram rejeitadas as duas hipóteses de estudo, demonstrando, com base em evidências estatísticas, que o conflito e a ambiguidade de função são percebidos pelos controllers brasileiros e, de fato, incidem negativamente sobre a satisfação no trabalho. Ademais, a amostra sustenta que o conflito de função afeta menos a satisfação no trabalho do que a ambiguidade. Além disso, os dados suportam que a falta de clareza sobre os objetivos e responsabilidades do controller acarretam em maiores níveis de ambiguidade de função e que o conflito percebido, aumentava em situações nas quais o executivo tinha que ignorar ou deixar de considerar uma regra ou política organizacional a fim de desempenhar alguma das suas funções. Finalmente, foi constatado que, apesar dos controllers perceberem esses dois tipos de tensão, em geral, eles se sentem satisfeitos com sua atual situação de trabalho. Uma das situações que menos contribuiu para a satisfação no trabalho dos controllers brasileiros foi a remuneração. / Empirical accounting evidences not only highlight the role of the controller in the companies, but also emphasize organizational situations that create stresses like role conflict and role ambiguity. In this context, this research aims to identify in what extent the role conflict and role ambiguity, perceived by Brazilian controllers, have an affect on job satisfaction. The sample comprised 114 controllers of the largest companies in Brazil, obtained from M&M magazine database. Data collection was conducted through a online questionnaire. The instrument used to measure the variables role conflict and role ambiguity was developed by Rizzo et al (1970), and to job satisfaction, was used the Job Satisfaction Index presented on Tarrant\'s (2008) work. We used the technique of structural equation modeling (PLS-SEM) as well as descriptive statistics for data analysis. The two study hypotheses were not rejected, demonstrating, based on statistical evidence, that role conflict and role ambiguity, perceived by Brazilian controllers, surely affect negatively on job satisfaction. Moreover, the sample sustains that the role conflict function affects less job satisfaction than role ambiguity. Furthermore, the data supports that the lack of clarity about the controller\'s goals and responsibilities, lead to higher levels of role ambiguity, and the perceived conflict increased in situations where the executive had to ignore or fail to consider a rule or organizational policy in order to perform any of its functions. Finally, it was found that despite the controllers realize these two types of stress, in general, they feel satisfied with their current employment situation. One of the situations that less contributed to the Brazilian controllers\' job satisfaction was the remuneration.

No description available.

No description available.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / A digital antenna control system has been designed and installed on a pedestal that was formerly used to drive a VHF array and that has now been replaced with an 11 meter S-Band parabolic reflector. In this Paper, the former analog tracking system will be described, showing all the drawbacks that made it unusable for S-Band. Subsequently, the development and implementation of the digital S-Band tracking system, using Labview, C++ & digital control theory will be discussed. Finally, there will be a comparison between the digital and analog system, too.

<p>CD8+ T cells are associated with long term control of virus replication to low or undetectable levels in a population of HIV+ therapy-naïve individuals known as virus controllers (VCs; <5000 RNA copies/ml and CD4+ lymphocyte counts >400 cells/µl). These subjects' ability to control viremia in the absence of therapy makes them the gold standard for the type of CD8+ T-cell response that should be induced with a vaccine. Studying the regulation of CD8+ T cells responses in these VCs provides the opportunity to discover mechanisms of durable control of HIV-1. Previous research has shown that the CD8+ T cell population in VCs is heterogeneous in its ability to inhibit virus replication and distinct T cells are responsible for virus inhibition. Further defining both the functional properties and regulation of the specific features of the select CD8+ T cells responsible for potent control of viremia the in VCs would enable better evaluation of T cell-directed vaccine strategies and may inform the design of new therapies. </p><p>Here we discuss the progress made in elucidating the features and regulation of CD8+ T cell response in virus controllers. We first detail the development of assays to quantify CD8+ T cells' ability to inhibit virus replication. This includes the use of a multi-clade HIV-1 panel which can subsequently be used as a tool for evaluation of T cell directed vaccines. We used these assays to evaluate the CD8+ response among cohorts of HIV-1 seronegative, HIV-1 acutely infected, and HIV-1 chronically infected (both VC and chronic viremic) patients. Contact and soluble CD8+ T cell virus inhibition assays (VIAs) are able to distinguish these patient groups based on the presence and magnitude of the responses. When employed in conjunction with peptide stimulation, the soluble assay reveals peptide stimulation induces CD8+ T cell responses with a prevalence of Gag p24 and Nef specificity among the virus controllers tested. Given this prevalence, we aimed to determine the gene expression profile of Gag p24-, Nef-, and unstimulated CD8+ T cells. RNA was isolated from CD8+ T-cells from two virus controllers with strong virus inhibition and one seronegative donor after a 5.5 hour stimulation period then analyzed using the Illumina Human BeadChip platform (Duke Center for Human Genome Variation). Analysis revealed that 565 (242 Nef and 323 Gag) genes were differentially expressed in CD8+ T-cells that were able to inhibit virus replication compared to those that could not. We compared the differentially expressed genes to published data sets from other CD8+ T-cell effector function experiments focusing our analysis on the most recurring genes with immunological, gene regulatory, apoptotic or unknown functions. The most commonly identified gene in these studies was TNFRSF9. Using PCR in a larger cohort of virus controllers we confirmed the up-regulation of TNFRSF9 in Gag p24 and Nef-specific CD8+ T cell mediated virus inhibition. We also observed increase in the mRNA encoding antiviral cytokines macrophage inflammatory proteins (MIP-1&alpha;, MIP-1&alpha;P, MIP-1&beta;), interferon gamma (IFN-&gamma;), granulocyte-macrophage colony-stimulating factor (GM-CSF), and recently identified lymphotactin (XCL1). </p><p>Our previous work suggests the CD8+ T-cell response to HIV-1 can be regulated at the level of gene regulation. Because RNA abundance is modulated by transcription of new mRNAs and decay of new and existing RNA we aimed to evaluate the net rate of transcription and mRNA decay for the cytokines we identified as differentially regulated. To estimate rate of mRNA synthesis and decay, we stimulated isolated CD8+ T-cells with Gag p24 and Nef peptides adding 4-thiouridine (4SU) during the final hour of stimulation, allowing for separation of RNA made during the final hour of stimulation. Subsequent PCR of RNA isolated from these cells, allowed us to determine how much mRNA was made for our genes of interest during the final hour which we used to calculate rate of transcription. To assess if stimulation caused a change in RNA stability, we calculated the decay rates of these mRNA over time. In Gag p24 and Nef stimulated T cells , the abundance of the mRNA of many of the cytokines examined was dependent on changes in both transcription and mRNA decay with evidence for potential differences in the regulation of mRNA between Nef and Gag specific CD8+ T cells. The results were highly reproducible in that in one subject that was measured in three independent experiments the results were concordant. </p><p>This data suggests that mRNA stability, in addition to transcription, is key in regulating the direct anti-HIV-1 function of antigen-speci&#64257;c memory CD8+ T cells by enabling rapid recall of anti-HIV-1 effector functions, namely the production and increased stability of antiviral cytokines. We have started to uncover the mechanisms employed by CD8+ T cell subsets with antigen-speci&#64257;c anti-HIV-1 activity, in turn, enhancing our ability to inhibit virus replication by informing both cure strategies and HIV-1 vaccine designs that aim to reduce transmission and can aid in blocking HIV-1 acquisition.</p> / Dissertation

Thesis (MScIng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: In the field of power electronic engineering, there is a need for a reconfigurable power electronic controller. Such a controller will enable engineers to stay focussed on their main field of study, not being side-tracked by the process of designing a high-speed digital controller to implement their ideas with. The design, construction and implementation of such a controller is presented in this paper. The design process involved defining the specifications of the controller and finding electronic components to satisfy them. After suitable components had been identified, a schematic design of the system was done. The netlist of the schematic was exported to a printed circuit board (PCB) design program, where the final layout was done and the connections between the devices routed. Before the PCB was manufactured, the firmware for the programmable logic devices (PLDs) was written to ensure that it fits in the selected PLDs of the system. After the PCB was manufactured and all its components fitted, it was tested and eventually used to implement the control of a shunt active power filter. / AFRIKAANSE OPSOMMING: Wanneer navorsing gedoen word in die drywings-elektronika gebied, word ’n behoefte vir ’n heropstelbare drywings-elektroniese beheerder ondervind. So ’n beheerder sal ingenieurs in staat stel om gefokus te bly op hulle hoof studieveld, sonder dat hulle aandag hoef te skenk daaraan om ’n ho¨e spoed digitale beheerder te ontwerp om hulle idees mee te implementeer. Die ontwerp, konstruksie en implementering van so ’n beheerder word in hierdie tesis voorgelˆe. Die ontwerp behels die bepaling van die spesifikasies van die beheerder en die opsporing van elektroniese komponente wat hierdie spesifikasies sal bevredig. Nadat geskikte komponente gevind is, is ’n skematiese ontwerp van die hele beheerder gedoen. Die lys van die verbindings tussen die komponente (Eng. netlist) is na die stroombaanbord ontwerp program gestuur, waar die finale uitleg van die bord gedoen is. Voordat die bord gemaak kon word, is die programmatuur vir die programmeerbare logikatoestelle geskryf om te verseker dat dit in die toestelle wat in die sisteem gebruik word, sal pas. Nadat die stroombaanborde vervaardig is en al die komponente daarop gemonteer is, is die bord getoets en uiteindelik gebruik om die beheer van ’n aktiewe drywingsfilter te implementeer.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

At Mondi Paper Ltd, Merebank, South of Durban, Paper Machine 2 has recently been transferred onto a Distributed Control System (DCS). This was seen as a good opportunity to enhance the control of the pulp feed to the machine. A prime concern in operating a paper machine is to ensure consistent set-point paper properties in the Cross-Direction (CD: ie. across the paper width) and in the Machine-Direction (MD: ie. along the paper length). Sophisticated adjustments are available to ensure an even feed of the stock (consistencies around 2% m/m wood fibres in water) from the head-box across the receiving width of the paper machine. The properties of prime interest as the pulp is pumped through the head-box distributor onto the receiving belt of the machine are the basis weight (fibre mass per unit area) and moisture content (per unit area). However, the distribution system is highly dependent on the properties of the stock as it arrives at the head-box. Variations in upstream chest levels, the supplied pressure, flow-rate and fibre/water ratio, all cause MD and even CD variations. The problems of maintaining steady conditions at the head-box are well known, and are understood to arise from sub-optimal control in the preceding section involving a blend chest and machine chest, amongst other items, where several pulp streams and dilution water are combined. A number of control loops are involved, but appear to require different tuning for different paper grades. Often individual loops are taken off-line. In this study, an understanding of the controller interactions in the stock preparation section has been developed by detailed dynamic modelling, including all of the existing control loops. The model is built up in a modular fashion using a basic element, having one input (which can collect multiple streams originating elsewhere) and four outputs, linked through a vessel of variable volume. Several basic elements are linked together to form the overall system. All of the necessary properties can be defined so that the model allows the simulation of all features of the network: vessels, pipes, junctions, valves, levels and consistencies. A set of first order differential equations is solved which includes total water balance, species mass balances, derivatives of flow controller action, and derivatives of supervisory controller action. Supervisory controllers for consistency or level cascade onto flow controllers. Flow controllers manipulate valves which give a first-order dynamic response of actual flow. Where valves are manipulated directly by the supervisory level, the flow controller is effectively bypassed. This study involves a constraint problem around the blend chest, resulting in a loss of specification at the paper machine. This was solved by the implementation of a static optimiser. Its objective function penalizes deviations from setpoint of five parameters (ratios, consistency and level) using respective weight factors. Both the model and its optimiser were included in a simulator designed with the graphical user interface (GUI) of Matlab. The simulator has then been used to explore control performance over the operating range, by means of a set of scenarios. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2004.