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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

A GPS-Based Autonomous Onboard Destruct System

Alves, Daniel F., Jr., Keith, Edward L. 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper examines the issues involved in replacing the current Range safety infrastructure with an autonomous range safety system based on GPS (Global Positioning Satellite) integrated navigation system solutions. Range safety is required in the first place because current launch vehicle navigation systems cannot meet a level of trust needed to determine if the mission is really under control and on course. Existing launch vehicle navigation is generally based on attitude and acceleration sensing instrumentation that are subject to drift, initialization errors and failures. Thus, a launch vehicle can easily be under the control of a seemingly operating navigation system, yet be steering the launch vehicle along an incorrect and dangerous flight path. Inertial-based navigation systems are good, but they cannot be trusted. The function of Range safety is to assure that untrustworthy navigation is backed up with a trusted system that has positive knowledge of the launch vehicle location, and the intelligence to decide when and where a launch vehicle must be destroyed. Combining inertial navigation, GPS derived position information and knowledge-based computer control has the potential to provide trusted and autonomous Range safety functions. The issues of autonomous Range safety are addressed in this paper.
22

Análise de veículos para atividades agrícolas por meio do consumo de combustível e torque na tomada de potência

Thomas, Carlos Alberto Kern January 2010 (has links)
Na hora de investir na compra de um novo trator o empresário do agronegócio se coloca diante da difícil missão de fazer uma escolha racional entre os diversos modelos comercias dos diferentes fabricantes e das suas reais necessidades. O objetivo principal deste trabalho foi desenvolver um ferramental que permita obter informações para a comparação teórica entre as demandas de torque e potência exigidas em trabalho de campo de um trator e os resultados de testes convencionais realizados em bancadas dinamométricas.Para tanto, foram realizados ensaios em tratores comerciais de variadas marcas e modelos sob condições de laboratório com um banco dinamométrico acoplado a tomada de força, seguindo a norma OECD “Code 2” - Standard Code for the Official Testing of Agricultural Tractors. Nestes testes determinou-se, entre outras características, o consumo específico de combustível nas diversas situações solicitadas pela norma. No campo foram executados sucessivos conjuntos de ensaios registrando níveis de torque e rotação do motor, necessários para caracterizar o perfil de desempenho na realização de diferentes atividades de um trator agrícola.O mesmo aparato adotado para as medições de laboratório foi utilizado nas medições em campo, com exceção da medida de consumo de combustível, da rotação do motor e do torque demandado, sendo que para este último fez-ae uso de um sistema digital de telemetria. Foram realizados estudos estatísticos para investigar as incertezas das medições associadas ao conjunto de sensores, transdutores e sistema de aquisição de dados usados nos testes.Os resultados alcançados nos diversos testes de laboratório formaram um banco de dados contendo as respectivas informações técnicas que seram disponibilizados em uma página da Internet. A análise estatística destes dados permitiu estabelecer limites para validar o sistema de medição desenvolvido e a comparação entre resultados de campo e de laboratório. Seguindo esta metodologia pode-se tomar uma decisão racional entre os diferentes modelos de trator agrícola. / While investing a new tractor that can live up to their demands, the agrobusiness entrepreneur encounters the difficult task of making a rational choice between different models from different manufacturers. The aim of this work is to develop a tool that provides information for the theoretical comparison between demands of torque and power in a tractor field work, as well as the results of conventional dynamometer tests. Tests were performed in laboratory, with commercial tractors of varied marks and models, with a dynamometric bench connected to power take-off according to “Code 2” - Standard Code for the Official Testing of Agricultural Tractors. These tests determine, among others characteristics, the specific fuel consumption in the different situations required by standard. In the field, a successive sets of tests are executed registering levels of torque and engine rotation, which are necessary to characterize a performance profile in the accomplishment of different activities performed by an agricultural tractor.The same apparatus of measurement adopted for laboratory tests was used for field tests, with the exception of fuel consumption measurement, engine rotation and demanded torque. The latter makes use of a digital telemetry system. Statistical studies were carried to investigate the uncertainties of the measurements associated with the set of sensors, transducers and data acquisition system used in the tests.The results achieved in the different laboratory tests form a database of technical information.The statistical analysis of the data allowed the establishment of limits to validate the developed measurement system; and the comparison between laboratory and field results. Following this methodology can assist in a rational decision making among the different models of agricultural tractor.
23

Tillståndskontroll av spårväxlar med mätutrustning monterad på tåg i reguljärtrafik

Rengmyr, Simon January 2017 (has links)
From 2000 to 2015, the cost of operation and maintenance (including reinvestment) and traffic control has increased from approximately three billion to over nine billion Swedish kronor annually. By making more frequent measurements of track irregularities and identifying trends earlier, accurate and effective maintenance can be performed. Therefore, in the industry and academy, different measurement solutions are tested to measure the state of railroad tracks in a simple and more frequent manner. One of the solutions is to use measuring systems mounted on trains in regular traffic. By using regular scheduled services, a higher cost effectiveness regarding inspection frequency can be achieved. When the measuring equipment is mounted on freight trains, a measurement with considerably higher axle load can also be performed. In the course of this work, a literature study have been conducted and a number of scientific articles and reports have been studied at depth. There is a number of different systems that have been manufactured to be mounted on rolling stock in regular service. Different solutions are applied to perform the measurements. Acceleration sensors are robust and reliable, which is necessary because they will be mounted in an exposed environment. A difference that has been identified is the installation of accelerometer sensors that are either mounted before or after the primary suspension. Before suspension the sensors are mounted on the axle box and, after suspension the sensors are mounted on the train bogie. The engineering company Damill is working within monitoring solutions and has developed equipment for mounting on trains in regular traffic called Tracklogger. Earlier evaluations of the equipment have been made with focus on comparison with machine inspections. There is a difference between the technology used in track recording vehicles and the technology that Tracklogger uses, such comparison is not entirely appropriate. In discussion with Damill the focus of this work has been to see if recordings of switches can be linked to maintenance actions. Since the equipment is in the development stage it is important that the measurement data collected is critically reviewed with regard to what information it delivers. The measurements have been carried out on switches in the main train track on track number 119 between Luleå and Boden and the mining company LKAB's ore wagon has been a tool carrier.  Five out of eight cases, a maintenance action can be linked to reduced measured values of switches with fixed crossing points. In one case, maintenance action has increased the measured value. In two cases, there is no signifcant difference in the measured value associated with maintenance actions. In previous evaluation, it was determined that it is good repeatability in the measured position, but not as high repeatability in the measured size. A number of switches have been studied to check the repeatability of the measurement. As the train runs in acircle run in Luleå harbor, there will be a limited number of occasions the equipment is running in the same direction in combination with the sensors on the same axle in the bogie, which may effect the measurement results. When analyzing the repeatability of five passages where the direction of travel is not taken into account, it is determined that three out of five passages show a good repeatability. The repeatability of the measurement is suspected of being related to the condition, as significantly greater differences in the measured signal are obtained just before a maintenance action has been taken.
24

Onboard Propellant Gauging For Spacecraft

Lal, Amit 01 1900 (has links)
Estimation of the total mission life of a spacecraft is an important issue for the communication satellite industries. For accurate determination of the remaining mission life of the satellite it is essential to estimate the amount of propellant present in the propellant tank of the spacecraft at various stages of its mission life. Because the annual revenue incurred from a typical communication satellite operating at its full capacity is on the order of millions of dollars, premature removal of spacecraft from their orbits results in heavy losses. Various techniques such as the bo okkeeping method, the gas law method, numerical modeling techniques, and use of capacitive sensors have been employed in the past for accurate determination of the amount of propellant present in a spacecraft. First half of the thesis is concerned with sensitivity analysis of the various propellant gauging techniques, that is, estimating the e ects of the uncertainty in the instruments employed in the propellant gauging system on the onboard propellant estimation. This sensitivity analysis is done for three existing propellant gauging techniques – gas injection method, book-keeping method and the propellant tank heating method. A comparative study of the precision with which the onboard propellant is estimated by the three techniques is done and the primary source of uncertainty for all the three techniques is identified. It is illustrated that all the three methods — the gas injection method, the book-keeping method and the propellant tank heating method — are inherently indirect methods of propellant gauging, as a consequence of which, the precision with which the three techniques estimate the residual propellant decreases towards the end of mission life of the spacecraft. The second half of the thesis explores the possibility of using a new propellant tank configuration, consisting of a truncated cone centrally mounted within a spherical propellant tank, to measure the amount of liquid propellant present within the tank. The liquid propellant present within the propellant tank orients itself in a geometry, by virtue of its dominant surface tension force in zero-g condition, which minimizes its total surface energy. Study reveals that the amount of liquid propellant present in the tank can thus be estimated by measuring the height of the propellant meniscus within the central cone. It is also observed that, unlike gas law metho d, bookkeeping method or the propellant tank heating metho d, where the precision of the estimated propellant fill-fraction decreases towards the end-of-life of the spacecraft, for the proposed new configuration the precision increases.
25

Diesel Soot Oxidation Catalyst Filter System Design

Genc, Volkan Eyup 01 July 2005 (has links) (PDF)
The objective of this study was onboard testing of a mixed metal oxide diesel soot oxidation catalyst composing of oxides of lead and cobalt previously developed in our lab, by mounting a diesel particulate filter (DPF), which is coated with this catalyst, to the exhaust stream of a diesel vehicle. Commercial wall flow type DPF&rsquo / s (Corning EX-80) were coated with the catalyst by a slurry wash-coating procedure and then mounted on the exhaust stream of a diesel light duty vehicle (LDV) provided by TOFAS (FIAT Doblo 1.9 JTD). These vehicles were driven on the rollers of the chassis dynamometer at constant speed and gear for two different loading conditions and on a standard driving cycle (NEDC) in the Test and Emission Laboratory of TOFAS-FIAT. The exhaust gases were analyzed for NOx, CO, CO2, THC and PM. The pressure drop caused by the filter was monitored during these tests as an indication of soot accumulation on the filter with the help of pressure sensors placed before and after the filter. Also temperatures before, inside and after the filter were monitored by means of thermocouples. Three different filters were tested in this manner: (1) Monocoated (CoOx), (2) Sequential PbOx coated over CoOx (PbOx/CoOx), (3) Simultaneously coated (PbCoOx). Also tests with the uncoated filter were performed to determine the pressure drops as a result of non-catalytic soot oxidation. The performances of the catalytic filters were evaluated by determining the temperature at which the soot oxidation rate on the filter equals the soot production rate in the engine (balance point temperature-Tbal). This temperature was used for comparing the catalytic activity of the supported catalyst with that of the powder form tested in the laboratory, i. e. Tpeak. The results of the onboard test were in parallel with the previous laboratory studies with similar catalytic activity temperatures. The continuous regeneration temperatures (Tbal) obtained in onboard tests with PbOx/CoOx and PbCoOx filters of about 370oC, which was close to the values attained in the lab study with the same mixed metal oxide catalyst having a Tpeak value of 385oC. Also the PM emissions during the tests were complying with the current EURO-IV emission limits.
26

Análise de veículos para atividades agrícolas por meio do consumo de combustível e torque na tomada de potência

Thomas, Carlos Alberto Kern January 2010 (has links)
Na hora de investir na compra de um novo trator o empresário do agronegócio se coloca diante da difícil missão de fazer uma escolha racional entre os diversos modelos comercias dos diferentes fabricantes e das suas reais necessidades. O objetivo principal deste trabalho foi desenvolver um ferramental que permita obter informações para a comparação teórica entre as demandas de torque e potência exigidas em trabalho de campo de um trator e os resultados de testes convencionais realizados em bancadas dinamométricas.Para tanto, foram realizados ensaios em tratores comerciais de variadas marcas e modelos sob condições de laboratório com um banco dinamométrico acoplado a tomada de força, seguindo a norma OECD “Code 2” - Standard Code for the Official Testing of Agricultural Tractors. Nestes testes determinou-se, entre outras características, o consumo específico de combustível nas diversas situações solicitadas pela norma. No campo foram executados sucessivos conjuntos de ensaios registrando níveis de torque e rotação do motor, necessários para caracterizar o perfil de desempenho na realização de diferentes atividades de um trator agrícola.O mesmo aparato adotado para as medições de laboratório foi utilizado nas medições em campo, com exceção da medida de consumo de combustível, da rotação do motor e do torque demandado, sendo que para este último fez-ae uso de um sistema digital de telemetria. Foram realizados estudos estatísticos para investigar as incertezas das medições associadas ao conjunto de sensores, transdutores e sistema de aquisição de dados usados nos testes.Os resultados alcançados nos diversos testes de laboratório formaram um banco de dados contendo as respectivas informações técnicas que seram disponibilizados em uma página da Internet. A análise estatística destes dados permitiu estabelecer limites para validar o sistema de medição desenvolvido e a comparação entre resultados de campo e de laboratório. Seguindo esta metodologia pode-se tomar uma decisão racional entre os diferentes modelos de trator agrícola. / While investing a new tractor that can live up to their demands, the agrobusiness entrepreneur encounters the difficult task of making a rational choice between different models from different manufacturers. The aim of this work is to develop a tool that provides information for the theoretical comparison between demands of torque and power in a tractor field work, as well as the results of conventional dynamometer tests. Tests were performed in laboratory, with commercial tractors of varied marks and models, with a dynamometric bench connected to power take-off according to “Code 2” - Standard Code for the Official Testing of Agricultural Tractors. These tests determine, among others characteristics, the specific fuel consumption in the different situations required by standard. In the field, a successive sets of tests are executed registering levels of torque and engine rotation, which are necessary to characterize a performance profile in the accomplishment of different activities performed by an agricultural tractor.The same apparatus of measurement adopted for laboratory tests was used for field tests, with the exception of fuel consumption measurement, engine rotation and demanded torque. The latter makes use of a digital telemetry system. Statistical studies were carried to investigate the uncertainties of the measurements associated with the set of sensors, transducers and data acquisition system used in the tests.The results achieved in the different laboratory tests form a database of technical information.The statistical analysis of the data allowed the establishment of limits to validate the developed measurement system; and the comparison between laboratory and field results. Following this methodology can assist in a rational decision making among the different models of agricultural tractor.
27

Análise de veículos para atividades agrícolas por meio do consumo de combustível e torque na tomada de potência

Thomas, Carlos Alberto Kern January 2010 (has links)
Na hora de investir na compra de um novo trator o empresário do agronegócio se coloca diante da difícil missão de fazer uma escolha racional entre os diversos modelos comercias dos diferentes fabricantes e das suas reais necessidades. O objetivo principal deste trabalho foi desenvolver um ferramental que permita obter informações para a comparação teórica entre as demandas de torque e potência exigidas em trabalho de campo de um trator e os resultados de testes convencionais realizados em bancadas dinamométricas.Para tanto, foram realizados ensaios em tratores comerciais de variadas marcas e modelos sob condições de laboratório com um banco dinamométrico acoplado a tomada de força, seguindo a norma OECD “Code 2” - Standard Code for the Official Testing of Agricultural Tractors. Nestes testes determinou-se, entre outras características, o consumo específico de combustível nas diversas situações solicitadas pela norma. No campo foram executados sucessivos conjuntos de ensaios registrando níveis de torque e rotação do motor, necessários para caracterizar o perfil de desempenho na realização de diferentes atividades de um trator agrícola.O mesmo aparato adotado para as medições de laboratório foi utilizado nas medições em campo, com exceção da medida de consumo de combustível, da rotação do motor e do torque demandado, sendo que para este último fez-ae uso de um sistema digital de telemetria. Foram realizados estudos estatísticos para investigar as incertezas das medições associadas ao conjunto de sensores, transdutores e sistema de aquisição de dados usados nos testes.Os resultados alcançados nos diversos testes de laboratório formaram um banco de dados contendo as respectivas informações técnicas que seram disponibilizados em uma página da Internet. A análise estatística destes dados permitiu estabelecer limites para validar o sistema de medição desenvolvido e a comparação entre resultados de campo e de laboratório. Seguindo esta metodologia pode-se tomar uma decisão racional entre os diferentes modelos de trator agrícola. / While investing a new tractor that can live up to their demands, the agrobusiness entrepreneur encounters the difficult task of making a rational choice between different models from different manufacturers. The aim of this work is to develop a tool that provides information for the theoretical comparison between demands of torque and power in a tractor field work, as well as the results of conventional dynamometer tests. Tests were performed in laboratory, with commercial tractors of varied marks and models, with a dynamometric bench connected to power take-off according to “Code 2” - Standard Code for the Official Testing of Agricultural Tractors. These tests determine, among others characteristics, the specific fuel consumption in the different situations required by standard. In the field, a successive sets of tests are executed registering levels of torque and engine rotation, which are necessary to characterize a performance profile in the accomplishment of different activities performed by an agricultural tractor.The same apparatus of measurement adopted for laboratory tests was used for field tests, with the exception of fuel consumption measurement, engine rotation and demanded torque. The latter makes use of a digital telemetry system. Statistical studies were carried to investigate the uncertainties of the measurements associated with the set of sensors, transducers and data acquisition system used in the tests.The results achieved in the different laboratory tests form a database of technical information.The statistical analysis of the data allowed the establishment of limits to validate the developed measurement system; and the comparison between laboratory and field results. Following this methodology can assist in a rational decision making among the different models of agricultural tractor.
28

Ledarskap till sjöss : Utmaningar med multikulturellt ledarskap ombord i fartyg / Leadership at sea : Multicultural leadership challenges onboard

Andersson, Klara January 2018 (has links)
Syftet med detta arbete är att undersöka utmaningarna med multikulturellt ledarskap till sjöss, och hur dessa skiljer sig från multikulturellt ledarskap iland. Från tidigare forskning och litteratur samt med hänsyn till de speciella förhållandena ombord identifieras fem punkter för ett lyckat multikulturellt ledarskap till sjöss. Dessa punkter har sedan legat till grund för en intervjuguide, som använts i intervjuer med tolv sjömän ombord på ett fartyg i svenska handelsflottan. Sjömännen har bland annat tillfrågats om hur de tycker att ett bra ledarskap ska vara, deras förväntningar på ledarskap och hur miljön ombord påverkar dem. Av sjömännens svar och åsikter under intervjuerna har det framgått att de viktigaste egenskaperna (enligt sjömännen) hos en ledare är att vara rättvis, snäll och kunnig. Sjömännen är medvetna om förväntningar på ledarskap som tillhör deras roll ombord, men reflekterar inte nämnvärt över olika kulturers förväntningar på deras roll. Detta kan ha sin förklaring i att, utifrån intervjuerna och litteraturgenomgången, kan man uppfatta att ombord råder en fartygsspecifik kultur. Det är denna fartygsspecifika kultur som besättningen uppmärksammar och anpassar sig till, och den egna nationella kulturen blir sekundär. Avslutningsvis bedöms den största utmaningen med multikulturellt ledarskap till sjöss att kunna vara en rättvis och snäll ledare i en isolerad och påfrestande miljö. / The purpose of this study is to investigate possible challenges regarding multicultural leadership at sea, and to see if these differ from challenges connected to multicultural leadership ashore. Considering the special conditions onboard a ship, and based on previous studies and literature, five components for successful multicultural leadership at sea has been identified. These five components have been the base of an interview guide, which has been used to conduct interviews with twelve seafarers onboard a Swedish flagged ship. The seafarers were asked what they consider to be good leadership, their expectations on leadership and how they feel affected by the environment onboard. According to the interviews, the seafarers feels that the most important traits for a leader is to be fair, kind and knowledgeable. The seafarers appear to be aware of the expectations connected to their roles onboard, but they do not seem to contemplate that people from different cultures may have different expectations on their role. Based on the literature study and the interviews, one can make out that a ship-specific culture rules the social environment onboard. The crewmembers seem to primarily adapt and adjust to this ship-specific culture, and their own national culture comes in second hand.  In conclusion, the biggest challenge of multicultural leadership at sea is recognized to be the ability to be a fair and kind leader in an isolated and wearying environment.
29

Palubní počítač pro vyhodnocení stavu a funkčních parametrů spalovacích motorů / Onboard computer for status and functional parameters evaluation of internal-combustion engine

Jaroš, David January 2008 (has links)
This thesis deals with design and realization of the onboard computer for evaluating functional parameters and status of the gas engine. Designed solution is consisted of two main parts. The first part is measuring unit whose obtains actual information on engine especially consumption of fuel, rotate per minutes and temperature of engine head. The second part of the solution is formed by pocket computer with appropriate software. The application for the pocket computer processes data from the measuring unit and from GPS receiver, which is integrated in pocket computer. Wireless bluetooth technology is used for data transfer between measuring unit and pocket computer. The application in pocket computer displays and records each of obtained and computed data.
30

Sjömän under en pandemi : En kvalitativ studie om hur en världsomspännande epidemi påverkat svenska sjöbefäl

Asp, Jakob January 2023 (has links)
Livet som sjöbefäl är i dagens samhälle ofta förknippat med en världsomspännande arbetsplats med goda arbetsförhållanden. Dessa förhållanden under vilka svenska sjöbefäl idag arbetar kan dock snabbt förändras under en världspandemi, då många länder världen över stänger sina gränser och försätter landet i isolation. Men till vilken grad har covid-19-pandemin påverkat svenska sjöbefäl i dess yrkesliv och privat? Med den frågeställningen som bakgrund är syftet med den här studien att undersöka och belysa hur de svenska sjöbefälen anser sig påverkats och vad som kan förbättras inför framtiden.                                                                           Genom kvalitativa, semistrukturerade intervjuer med 5 olika svenska sjöbefäl har den empiri som ligger till grund för resultatet samlats in. Resultatet visar bland annat att en absolut majoritet av de respondenter som medverkat i studien upplever att deras familjer i störst utsträckning påverkats och att detta faktum var den jobbigaste delen av att inte vara hemma under betydligt längre tidsperioder än vad dessa befäl vanligtvis är. Informanterna önskar se förändringar kring deras möjligheter till att mönstra av och på i framtiden. / The life as a merchant marine officer is often seen as a worldwide workplace with good working and living standards. However, the life standard onboard these vessels where the Swedish officers work can quickly change during a worldwide pandemic when a lot of countries close their borders and put themselves in isolation. So, to what degree are these officers private life and life onboard affected by the corona pandemic?                                                                                                                     With that questions as background the purpose of this thesis is to research how the world pandemic affected the Swedish marine officers as well as what they think needs to be changed in future. Through interviews with 5 different Swedish officers using a semi-structured way of interviewing, data answering these questions has been collected. The result of this research shows amongst other that an absolute majority of the officers that were interviewed found the family and relatives to be the toughest subject. They also point it out as the most affected part of their lives, mostly because of the long periods they all spent onboard their vessels. All the officers answered that they wanted to see some changes in the future when it comes to their sign on and sign off possibilities.

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