Search results for "LMA"
showing 10 items of 3320 documents
Descriptor-type Robust Kalman Filter and Neural Adaptive Speed Estimation Scheme for Sensorless Control of Induction Motor Drive Systems
2012
Abstract This paper deals with robust estimation of speed and rotor flux for sensorless control of motion control systems which use induction motors as actuators. Due to the observability lack of five and six order Extended Kalman Filters, speed is here estimated by means of a Total Least Square algorithm with Neural Adaptive mechanism. This allows the use of a fourth-order Kalman Filter for estimating rotor flux and to filter stator currents. To cope with motor-load parameter variations, a descriptor-type robust Kalman Filter is designed taking explicitly into account these variations. The descriptor-type structure allows direct translation of parameter variations into variations of the co…
Robustness Analysis of an Extended Kalman Filter for Sensorless Control of Induction Motors
2010
This paper deals with robustness analysis of Extended Kalman Filters (EKFs) for sensorless motion control of induction motors. Analysis is carried out by means of simulation experiments considering a conventional EKF, in which system and measurement noise covariance matrices are constant, and an adaptive EKF in which the system noise covariance matrix is updated on-line using a PID-type algorithm driven by the stator current estimation errors.
Velocity sensorless control of uncertain load using RKF tuned with an evolutionary algorithm and mu-analysis
2010
Abstract In case of a velocity control scheme for a load directly driven by an actuator, large variations of its parameters are problematic due to possible instability and large variations of the final performances. This performances are then decreasing if a sensorless control is implemented due to cost, reliability or application constraints. This paper proposes solutions to quickly and accurately tune an observer with a lower computer time consumption and lower conception time. A previous calculated state feedback is used as base for a Kalman filter with special noise matrices. An evolutionary algorithm optimizes the observers degrees of freedom all over the variations. The mu-analysis th…
Toward Successfully Integrating Mini Learning Games into Social Virtual Reality Environments : Recommendations for Improving Open and Distance Learni…
2017
Social virtual reality environments, also known as 3D virtual immersive environments, are threedimensional computer-generated virtual spaces that are increasingly used in attendance-based and distance education. Thanks to their unique characteristics that separate them from two-dimensional virtual learning environments, social virtual reality environments can enhance distance education efficacy when used in combination with applying instructional methodologies such as situated learning, experiential learning and game-based learning. The authors of this paper describe the design and findings of a research study on game-based learning in social virtual immersive environments. The research met…
Balancing ‘flexibility’ and ‘employability’: The changing role of general studies in the Finnish and Swedish VET curricula of the 1990s and 2010s
2019
This article analyses and compares the evolving role of general subjects in the curricula of initial upper secondary vocational education and training (VET) in Finland and Sweden during the 1990s and 2010s. The research illustrates how Bernstein’s concept of ‘pedagogic code’ supports comparative studies on principles guiding changes to curricula and how the role of general studies in VET has been redefined. The findings show that while a principle of ‘market relevance’ has been central to VET over the decades since the 1990s, it has been subject to varying interpretations. The shifts in interpretations have guided the organisation of VET in these two countries in different directions, incl…
Students’ self-reported learning outcomes after a business start-up education program
2019
The aim of the present study is to examine the breadth of influence of a business plan-based entrepreneurship education. This task is implemented by examining students’ (n = 227) self-reported learning outcomes concerning entrepreneurial skills, attitudes and abilities after education. In addition to proposing a classification of the self-reported learning outcomes, this study explores how these outcomes are related to the background characteristics of those taking part in an education program, and of the companies involved. Based on this study, four main areas of self-reported learning outcomes were found: (i) working-life key skills, (ii) management skills, (iii) entrepreneurial empowerme…
Sorption of heavy metals in the biomass of alga Palmaria palmata
2013
Sorption of heavy metals by the sea alga Palmaria palmata was investigated in laboratory conditions. The sorption process of the analytes was carried out with constant flow of the solutions through the algae samples. The Langmuir isotherm model was used to describe equilibria. The experiments confirmed that 50 min of exposure of algae with little heavy metal contamination in contaminated waters results in the increase of concentration of these analytes, proportional to their concentration in the tested waters. On the basis of the Langmuir isotherm direction factor, a = (c(a,max) × K)−1, affinity of heavy metals and algae increases in the following sequence: Mn2+ < Zn2+ ≈ Cd2+ &lt…
Combined effects of eutrophication and warming on polyunsaturated fatty acids in complex phytoplankton communities:A mesocosm experiment
2022
Climate change and eutrophication are among the main stressors of shallow freshwater ecosystems, and their effects on phytoplankton community structure and primary production have been studied extensively. However, their combined effects on the algal production of polyunsaturated fatty acids (PUFA), specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are currently unresolved. Moreover, the proximate reasons for changes in phytoplankton EPA and DHA concentrations are unclear, i.e., the relative importance of ecological (changes in the community composition) vs. ecophysiological (within taxa changes in EPA and DHA levels) factors. We investigated the responses of phytopla…
The impact of various cations on the sorption of manganese in the thallus of freshwater algae spirogyra sp. and sea algae palmaria palmata
2014
Abstract Due to their occurrence in very different conditions and high resistance to physical and chemical factors, algae are pioneers colonising new environments and their sorption properties are used in biomonitoring and water remediation. The efficiency of the process of heavy metal sorption in algae used for in situ tests depends on abiotic factors, such as the chemical composition of water. Freshwater algae Spirogyra sp. were used in tests. Algae were exposed in the laboratory in manganese chloride solutions with various contents of other cations, including heavy metals and macronutrients. It has been shown that some heavy metals may desorb manganese bound to the surface of algae as a …
Improved GNSS positioning exploiting a vehicular P2P infrastructure
2010
This paper considers the possibility to exploit external altitude measurements to improve the performance of a Kalman based GNSS receiver. The altitude measurements are provided by means of a peer to peer network, that is supposed to be based on the evolution of the 802.11 standard for the vehicular environment, namely the WAVE (802.11p). The performance of such a system are investigated for different characteristics of the aiding measurement and for a different number and disposals of the aiding peers. The aiding measurement is obtained starting from the altitude measurements that the other peers in the network send to the aided user. The experiments highlight the need for a parameter that…