1,721,172 research outputs found
Control-oriented low-order models for the transient analysis of a domestic electric oven in natural convective mode
No full textAlmost 25% of the overall environmental impact of buildings can be attributed to appliances, among which
electric domestic ovens represent a low-efficiency category when considering apartments. In order to improve
their low efficiency, usually lying between 10% and 12%, the oven industry is often stimulated to develop more
efficient technologies, among which there is the design of suitable strategies for the control of the oven center
temperature, as required by the EN 60350-1 European standard, which regulates the energy consumption test.
This work describes the simulation of the transient thermal behaviour of a domestic electric oven in natural
convection heating mode by means of dynamic models suitable for control design purposes. A lumped-parameter
approach based on the thermoelectric analogy was chosen, in order to obtain a low-order dynamic model with a
proper level of discretization which allowed to reproduce the main temperatures within the cavity, in particular
at the oven’s centre and the temperature sensed by the probe used for oven control during normal operating
conditions. Eight lumped parameters were introduced to represent walls, glass door, cavity air and temperature
probe, and three parameters to simulate the thermal behaviour of the heaters were considered, resulting in an
11-th order model. Moreover, the influence of non-linearized radiative terms on model accuracy was investigated,
leading to two different lumped-parameter, semi-physical models. Two sets of capacities and conductances
were identified for both the models through an optimization procedure based on experimental data,
giving a grey-box nature to the models; subsequently the prediction potential of the models was verified at
different temperature set-points
Distributed Detection of Local Phenomena with Wireless Sensor Networks
No full textThe use of small sensors that can communicate through wireless links and that are positioned over a wide area can allow to gather precise data about the occurrence of determined phenomena. Depending on the application scenario, the phenomenon to be detected can interest all sensors (global phenomenon (GP)), or just a subset of the deployed sensors (local phenomenon (LP)). One of the most interesting phenomena that can be monitored by wireless sensor networks is fire. In this paper a wireless sensor network configuration for fire detection applications is presented. A chain network is considered where in order to reduce the transmissions and then minimize the power consumptions each node makes a local decision about target absent/present considering its own observation and also the decision made by the previous node. Fusion rules for both the global and local phenomenon scenario are proposed, to minimize the error probability at the last stage of the chain
Not one less, the role of 4L in left-sided lung cancer: The message from the Polish experience
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Modelling of Natural Convective Heating of a Standard Wet Brick for Oven Energy Consumption Tests
Full text linkThe environmental impact of buildings is directly influenced by low-efficiency appliances like electric ovens. Their energy class is estimated through a test prescribed by the EN 60350 European standard, where a wet clay brick is heated under set conditions and the energy consumption is measured; throughout the test, particular attention is devoted to the control of air temperature. In this work, a transient model of the oven suitable for control design was realized including the heat and mass transfer within the brick. A lumped-parameter approach was used to ensure good predictive properties and low computational cost. The dynamics of the cavity air and the Pt500, which is used in normal operation to maintain the desired set point, was also included in the model. Model parameters were determined through an optimization procedure based on the experimental data collected during energy consumption tests with the oven in natural convective heating mode. The model was then validated. Good results were obtained in the prediction of both temperature and heating time
Dynamic model for convective heating of a wet brick during energy characterisation of domestic electric ovens
Full text linkElectric ovens usually represent a low-efficiency category among household appliances, influencing the overall environmental impact of buildings. The energy class of such devices is determined through a test procedure defined by the EN 60350 European standard, where a wet clay brick is heated under set conditions and accurate control of the air temperature during the test is required, which marks the importance of efficient control strategies. In this work a control-oriented dynamic model was devised to predict the transient thermal behaviour of the oven during energy consumption tests carried out in forced-convective mode, including the heat and mass transfer occurring between the wet brick and the cavity air. Model parameters were determined through an optimisation procedure based on experimental data. Comparisons with other sets of experimental data also allowed to validate the predictive capability of the model. The model predicts well the temperature of the cavity air, the Pt500 probe used as a temperature feedback and the core temperature of the brick with deviations lower than 10% after the heating phase of the cavity. The brick heating time and water loss are also captured by the model, with deviations lower than 6% for the former and 9% for the latter
Targets Sequence Optimisation for Low-Thrust Multiple Active Debris Removal Missions with Dynamic Programming
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