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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.
961

A Secondary Task Test for Evaluating Cognitive Load of MRP Pilots

Farshidi, Azadeh January 2017 (has links)
Remotely-controlled technologies are no longer limited to military applications, such as unmanned military airborne weapons or explosive diffuser robots. Nowadays we can see more and more of remotely controlled devices used as medical equipment, toys, and so forth. One of the most recent areas of interest is robotic telepresence, also known as Mobile Robot Presence (MRP), which provides the ability to interact socially and professionally with other people and even objects in remote locations. One of the known issues with using remotely-controlled devices is the cognitive overload which their operators (pilots) experience and MRP pilots are no exception. However, despite vast research on different ways to address this in military or medical scenarios, little has been done regarding MRPs. This thesis study aims to make a contribution in closing that gap by suggesting a method, developing a prototype implementing it; then conducting an empirical assessment of the method and the prototype as a part of a broader study on MRP, supported by Swedish Research Council. I have suggested a method comprised of a Secondary-task (ST) method and Subjective Rating Scales (SRS), in which the latter act as an evaluation method for the former. Both of them were used in an overarching study in search for the best control device amongst four chosen devices. I collected and analyzed secondary task performance data (e.g. response time, error rates), subjective user ratings, explicit rankings, and observations recordings. My analysis of the collected data shows that using a monitoring and response face recognition secondary task is a plausible method for the assessment of MRP pilot’s cognitive load.
962

Work-related well-being in the transformation of nursing home work

Mäkitalo, J. (Jorma) 13 June 2005 (has links)
Abstract The purpose of this study was three-fold: to analyze how the work-relatedness of well-being has been constructed by the presently prevailing work stress approach, to develop better ways of conceptualizing the work-relatedness of well-being on the basis of cultural historical activity theory, and to test these new conceptualizations with empirical data from two nursing homes for the elderly. An analysis of the development of work stress theory and previous studies of nursing homes showed that their foundations lie in the paradigmatic person – environment formulation which inhibits taking into account the activity of the individual, the changing of the work process and the specific context in which stress is experienced. With respect to work-related well-being two activity-theoretical hypotheses were developed: the object-dependedness of work-related emotions (object-dependent well-being) and the increased physical and psychological work load as a result of disturbances in the flow of work (disturbance load). An empirical analysis of the historical development of the two nursing homes showed how the function of the nursing homes had changed several times and continued to do so. The analysis also suggested that changes in the work-related well-being of the employees followed the developmental phases of the work activity. The second empirical analysis showed how the employees' explanatory models of both tiring- and strength- giving events were related to several historical, present and possible future aspects of the object of their work. Signs of individual motive development could be detected in the interviews. The third empirical analysis of videorecorded morning routine episodes showed how the current institutional script carried out by the employees collided with the residents' own script resulting in resident resistance which increased the physical and psychological workload of the employees. Focusing on disturbance load may uncover important sources of emotional distress and physical tiredness among employees. Understanding work-related well-being also as qualitatively developing object-dependent well-being points to the need to create a dialogue between the development of the collective activity and the object and motive development of individual employees.
963

Measuring Cognitive Load in Embodied Learning Settings

Skulmowski, Alexander, Rey, Günter Daniel 02 August 2017 (has links) (PDF)
In recent years, research on embodied cognition has inspired a number of studies on multimedia learning and instructional psychology. However, in contrast to traditional research on education and multimedia learning, studies on embodied learning (i.e., focusing on bodily action and perception in the context of education) in some cases pose new problems for the measurement of cognitive load. This review provides an overview over recent studies on embodied learning in which cognitive load was measured using surveys, behavioral data, or physiological measures. The different methods are assessed in terms of their success in finding differences of cognitive load in embodied learning scenarios. At the same time, we highlight the most important challenges for researchers aiming to include these measures into their study designs. The main issues we identified are: (1) Subjective measures must be appropriately phrased to be useful for embodied learning; (2) recent findings indicate potentials as well as problematic aspects of dual-task measures; (3) the use of physiological measures offers great potential, but may require mobile equipment in the context of embodied scenarios; (4) meta-cognitive measures can be useful extensions of cognitive load measurement for embodied learning.
964

Novel Concepts In Divisible Load Scheduling With Realistic System Constraints

Suresh, S 04 1900 (has links) (PDF)
No description available.
965

Design And Evaluation Of Some Stochastic Load Scheduling Algorithms In Distributed Computing Systems

Anand, L 09 1900 (has links) (PDF)
No description available.
966

Performance of Polyurea Retrofitted Unreinforced Concrete Masonry Walls Under Blast Loading

Ciornei, Laura January 2012 (has links)
Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.
967

Reconfiguração de sistemas de distribuição considerando incertezas através de fluxo de potência intervalar e sistemas imunológicos artificiais

Seta, Felipe da Silva 10 August 2015 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-19T10:47:34Z No. of bitstreams: 1 felipedasilvaseta.pdf: 1053075 bytes, checksum: 8a24a576cad55e9b46efe4bde9405104 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T17:44:56Z (GMT) No. of bitstreams: 1 felipedasilvaseta.pdf: 1053075 bytes, checksum: 8a24a576cad55e9b46efe4bde9405104 (MD5) / Made available in DSpace on 2016-01-25T17:44:56Z (GMT). No. of bitstreams: 1 felipedasilvaseta.pdf: 1053075 bytes, checksum: 8a24a576cad55e9b46efe4bde9405104 (MD5) Previous issue date: 2015-08-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho propõe uma metodologia para a resolução do problema de reconfiguração ótima de sistemas de distribuição de energia elétrica utilizando uma representação mais realista de parâmetros com incertezas. O objetivo é avaliar o impacto de se representar incertezas dos sistemas no problema de reconfiguração em relação a modelos tradicionais determinísticos. O modelo de reconfiguração probabilística proposto visa minimizar as perdas totais de energia considerando incertezas sobre a demanda e sobre a geração distribuída a partir da energia eólica, além de diferentes níveis de carregamento dos sistemas. A metodologia proposta é baseada na técnica meta-heurística Sistema Imunológico Artificial. Os fundamentos da matemática intervalar são incorporados em um fluxo de potência intervalar que modela as incertezas da demanda provenientes principalmente de erros de previsão e medição, bem como incertezas na geração por fontes eólicas devido a intermitências nos regimes de ventos. Desta forma, as variáveis de entrada intervalares são as demandas ativas e reativas das barras do sistema e os valores de velocidade de vento nas regiões das usinas eólicas. As incertezas da entrada são propagadas para as variáveis de saída do fluxo de potência, como as tensões nodais. Como resultado, as perdas totais de energia a serem minimizadas também são determinadas na forma intervalar. Uma metodologia para comparação de intervalos baseada na média e no raio dos intervalos é utilizada para determinar a topologia ótima. Restrições de tensão, radialidade e conectividade da rede são consideradas. O algoritmo proposto é testado em sistemas conhecidos da literatura. / The present work proposes a methodology to solve the problem of optimal reconfiguration of power distribution systems by using a more realistic representation of uncertain parameters. The objective is to evaluate the impact of representing uncertainties in the reconfiguration problem in relation to traditional deterministic models. The proposed probabilistic reconfiguration model aims at minimizing the total energy loss considering uncertainties on the load demand and the distributed generation from wind energy, as well as different load levels. The proposed methodology is based on the meta-heuristic technique Artificial Immune System. The interval mathematics fundamentals are embedded in an interval power flow that models the uncertainties of load forecast and measurements, as well as uncertainties due to the intermittences of the wind. Therefore, the input interval variables are the active and reactive loads at the network nodes and the wind speed in the regions where the wind farms are installed. The input uncertainties are thus propagated to the output power flow variables as the nodal voltages. As a result, the total energy losses to be minimized are also given in interval form. A methodology for comparing intervals that is based on the interval average and size is used to determine the best topology. Voltage constraints, radial configuration and network connectivity are considered. The proposed algorithm is tested in systems known in the literature.
968

SELF-SUFFICIENT OFF-GRID ENERGY SYSTEM FOR A ROWHOUSE USING PHOTOVOLTAIC PANELS COMBINED WITH HYDROGEN SYSTEM : Master thesis in energy system

Maxamhud, Mahamed, Shanshal, Arkam January 2020 (has links)
It is known that Sweden is categorised by being one of the regions that experience low solar radiation because it is located in the northern hemisphere that has a low potential of solar radiation during the colder seasons. The government of Sweden aim to promote a more sustainable future by applying more renewable initiative in the energy sector. One of the initiatives is by applying more renewable energy where PV panels will play a greater role in our society and in the energy sector. However, the produced energy from the PV panels is unpredictable due to changes in radiation throughout the day. One great way to tackle this issue is by combining PV panels with different energy storage system. This thesis evaluates an off-grid rowhouse in Eskilstuna Sweden where the PV panels are combined with a heat pump, thermal storage tank, including batteries and hydrogen system. The yearly electrical demand is met by utilizing PV panels, battery system for short term usage and hydrogen system for long-term usage during the colder seasons. The yearly thermal demand is met by the thermal storage tank. The thermal storage tank is charged by heat losses from the hydrogen system and thermal energy from heat pump.The calculations were simulated in Excel and MATLAB where OPTI-CE is composed with different components in the energy system. Furthermore, the off-grid household was evaluated from an economic outlook with respect to today’s market including the potential price decrease in 2030.The results indicated that the selected household is technically practicable to produce enough energy. The PV panels produces 13 560 kWh annually where the total electrical demand reaches 6 125 kWh yearly (including required electricity for the heat pump). The annual energy demand in terms of electricity and thermal heat reaches 12 500 kWh which is covered by the simulated energy system. The overproduction is stored in the batteries and hydrogen storage for later use. The back-up diesel generator does not need to operate, indicating that energy system supplies enough energy for the off-grid household. The thermal storage tank stores enough thermal energy regarding to the thermal load and stores most of the heat during the summer when there are high heat losses due to the charge of the hydrogen system. The simulated energy system has a life cycle cost reaching approximately k$318 with a total lifetime of 25 years. A similar off-grid system has the potential to reduce the life cycle cost to k$195 if the energy system is built in 2030 with a similar lifespan. The reduction occurs due to the potential price reduction for different components utilized in the energy system.
969

Brandbelastning i träbyggnader : Jämförande beräkning och kartläggning om hur branschen hanterar permanet brandbelastning

Eriksson, Kajsa, Jenny, Löfgren January 2020 (has links)
Wood is a renewable material, it is strong in relation to its weight, climate smart but also combustible. Owing to its many advantages and the easy access in Sweden, wood is motivated as a topical building material. However, the aspects related to the combustible nature need to be considered in the design of buildings with a wooden frame. Whether and in such cases how to take into account the increased permanent fire load is a problem of which there are shared opinions. Today's regulatory framework is unclear in some aspects in its formulation and thus leaves room for interpretation. The purpose of this work is to investigate the reasonableness of tabulated data for permanent fire load and the sharp boundary between a BR1 building and a BR0 building but also by surveying how the industry handles the issue. In order to assess the reasonableness for the tabulated data, the method has been calculations with two different methods; one that follows BBR's guidelines (method 1) and another where calculations of the charring depth (method 2) have been performed, as well as a survey and a literature study. The result from the calculations in method 1 shows that in order for the level of the total fire load not to exceed the standard value for a residence of 800 MJ/m2, a low coefficient is required, and thus in principle all wood is assumed to be protected. According to the calculations in method two, it is possible to read out how the permanent fire load is affected by different protective linings and carbonation rates. The survey shows that the most common way to dimension fire protection is through simplified sizing, which entails that one does not have to consider whether the permanent fire load increases due to a combustible frame. There are divided opinions about whether Boverket's rules are enough to achieve adequate protection and how to handle it. The literature study shows that for the timber frame to be counted as fully protected it needs to be three layers of fire gypsum board in the ceiling and that two layers on the walls. Several conclusions can be drawn; the calculations indicate that a permanent fire load of 200 MJ/m2 (2013:11) is unreasonable in a wooden frame building also that if the permanent fire load is considered it becomes costly both economically and in terms of space. Even that Boverket's rules need to be clarified and adapted further against tall wood buildings and that fire projectors work differently and the experience of working with tall wood buildings differs greatly.
970

Prova de carga rápida com recalque estabilizado / Stabilized settlements by quick maintained load test

Almeida, Marina Prearo Benvenutti 25 June 2009 (has links)
A prova de carga estática lenta é tradicional na engenharia de fundações, no mundo todo. Mas sua realização pode envolver um tempo excessivo e, por isso, tem havido tentativas para reduzir sua duração. O ensaio rápido, ao contrário, é realizado em apenas algumas horas, mas, sem dúvida alguma, os recalques obtidos nesse ensaio são bem inferiores aos do ensaio lento. Uma alternativa promissora pode ser o ensaio pelo método do equilíbrio, que parece reunir as vantagens daquelas duas modalidades. Nesse método, utiliza-se a carga mantida apenas no início do estágio e, depois, deixa-se a carga diminuir livremente até atingir uma condição de equilíbrio, com recalque e carga estabilizados, em cada estágio. Neste trabalho, são apresentadas comparações entre as três modalidades, em ensaios de placa, em modelo, em solo arenoso colapsível, em duas condições: inundado e não-inundado. / The slow mantained load is a traditional test in foundations engineering worldwide. Nevertheless, its implementation may take too long, so there have been attempts to reduce its duration. The quick mantained load test, in other hand, takes only a few hours to be accomplished and the obtained settlements are lower than the slow maintained load test. The method of equilibrium is an attractive option. It seems to combine the advantages of these two methods, using maintained load at the beggining of the stage and then allowing to freely decrease the load to reach its equilibrium. This study compares these three methods in two conditions: non-flooded and flooded colapsive sandy-soil model.

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