Flow mixing is an important process for many microfluidic applications. Efficient mixing is difficult in microscale channels owing to laminar flow. Disturbing the flow stream by modifying channel geometries or embeddi...
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Flow mixing is an important process for many microfluidic applications. Efficient mixing is difficult in microscale channels owing to laminar flow. Disturbing the flow stream by modifying channel geometries or embedding barriers improves the mixing rate. In this study, a three-dimensional (3-D) passive micromixer with propeller blades fabricated by two-photon polymerization (TPP) technology is embedded in the channel for fluid mixing. The propeller blades are designed to disturb the laminar flow in three dimensions to improve the mixing rate. Screw-shaped and flat blades are compared. The experimental results indicate that the screw-shaped propeller provides additional streamlines in the Z direction, which enhances the mixing efficiency. Finally, this phenomenon was verified through simulation.
Cooperative dynamic object manipulation can extend the manipulation capabilities of robot-robot and human-robot teams. In order to be able to inject energy into various suspended objects of unknown parameters, in this...
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ISBN:
(纸本)9781479969357
Cooperative dynamic object manipulation can extend the manipulation capabilities of robot-robot and human-robot teams. In order to be able to inject energy into various suspended objects of unknown parameters, in this paper we propose an adaptive controller which combines reinforcement learning with energy based swing-up control. The proposed controller is successfully verified in a single robot and human-robot experimental setup for different types of suspended objects.
This paper introduces a systematic approach to synthesize linear parameter-varying (LPV) representations of nonlinear (NL) systems which are originally defined by control affine state-space representations. The conver...
This paper introduces a systematic approach to synthesize linear parameter-varying (LPV) representations of nonlinear (NL) systems which are originally defined by control affine state-space representations. The conversion approach results in LPV state-space representations in the observable canonical form. Based on the relative degree concept of NL systems, the states of a given NL representation are transformed to new coordinates that provide its normal form. In the SISO case, all nonlinearities of the original system are embedded in one NL function which is factorized to construct the LPV form. An algorithms is proposed for this purpose. The resulting transformation yields an LPV model where the scheduling parameter depends on the derivatives of the inputs and outputs of the system. In addition, if the states of the NL model can be measured or estimated, then the procedure can be modified to provide LPV models scheduled by these states. Examples are included for illustration.
This paper presents a computationally efficient method for modelling an impact of the converter drive on the power grid. The formalized variable structure method (FVSM) allows for comprehensive studies of the effect o...
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This paper presents a computationally efficient method for modelling an impact of the converter drive on the power grid. The formalized variable structure method (FVSM) allows for comprehensive studies of the effect on the power grid and examining the relation between this effect and the number of drive and feeding line parameters. In order to obtain a comprehensive model along with the model of the power grid, the parameters that are applied originate from a drive of a coal-fired power station. These parameters have been determined based on assessment and estimation. The estimation process was conducted with the aid of a model that allows for the commutation of power electronic elements. The authors confirmed that the model was correct by comparing empirical and theoretical voltage and current waveforms. Harmonic content of the voltage and current in the power grid which feeds the drive are considered to be the measure of the converter drive impact on the power grid. The standard method for the reduction of a harmonic content in the voltage and current involves the application of line reactors and distribution or converter transformers. As an example, the authors determine the impact of the drive on the power grid with respect to the adopted parameters of the line reactor. This example presents FVSM abilities with regard to simulation of complex systems that contain power grid components and converter drives.
Results of a measurement and analysis of vibro-acoustic signals generated by two low power vertical-axis wind turbines that are installed on the roof of the Electric Power Institute at Opole University of Technology a...
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Results of a measurement and analysis of vibro-acoustic signals generated by two low power vertical-axis wind turbines that are installed on the roof of the Electric Power Institute at Opole University of Technology are presented in the paper. The study considers a Darrieus and a Savonius type wind turbines of rated power 1 kW each. For registration of the vibrations of the turbine mast three uniaxial accelerometers and a measurement equipment from Brel & Kjr were applied. The measurement setup is presented in the paper. A comparative analysis of the registered data in the time and time-frequency domains was performed. Results depict changes in the recorded signals in time and frequency under different meteorological conditions, i.e. for different wind speed values. Based on the achieved results significant differences in the mast vibrations of the two kinds of wind turbines were stated.
The context awareness of mobile devices is broadly researched area as it improves the functionality, usability, safety of usage and intelligence of the device as perceived by its user. The special type of context is d...
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The context awareness of mobile devices is broadly researched area as it improves the functionality, usability, safety of usage and intelligence of the device as perceived by its user. The special type of context is driving a car. The awareness of a mobile device whose user drives a car may allow to disable some features like making and taking phone calls and enable other features like e.g. navigation thus improving the safety of the user. The paper presents the results of a research on acoustic detection of car driving based on over 60 h of collected data. The modification of traditional k-nearest neighbors classification algorithm is proposed that allows for learning and adaptation of classifier configuration. The proposed approach significantly improves both the sensitivity and specificity of the classifier comparing to the classifier based only on oine training data. The challenges in performing the acoustic wave analysis using highly heterogeneous devices like mobile phones are discussed.
In this paper, non-linear systems (hydraulic tank configurations) were analyzed using a technique of fault detection and isolation based on a Takagi-Sugeno fuzzy model. The system state vector was obtained by means of...
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In this paper, non-linear systems (hydraulic tank configurations) were analyzed using a technique of fault detection and isolation based on a Takagi-Sugeno fuzzy model. The system state vector was obtained by means of sliding mode observers, and then the signal-residual is generated by comparing the estimated and measured outputs. The isolation problem was solved using Neural Networks. From the resulting active or inactive signal-residuals, the faulted elements of the system are easily identified. The method proposed represents a hybrid fault diagnosis technique.
Texture classification and segmentation have been studied using various approaches. The mean Grey-Level Co-occurrence Matrix, introduced by the authors, gives statistical features relatively insensitive to rotation an...
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ISBN:
(纸本)9783642325472
Texture classification and segmentation have been studied using various approaches. The mean Grey-Level Co-occurrence Matrix, introduced by the authors, gives statistical features relatively insensitive to rotation and translation. On the other hand, texture analysis based on fractals is an approach that correlates texture coarseness and fractal dimension. By combining the two types of features, the discrimination power increases. The paper introduces the notion of effective fractal dimension which is an adapting fractal dimension to classification of texture and is calculated by elimination of a constant zone which appears in all textured images. In the case of colour images, we proposed a classification method based on minimum distance between the vectors of the effective fractal dimension of the fundamental colour components. The experimental results to classify real land textured images validate that effective fractal dimension offers a grater discrimination of classes than typical fractal distance based on complete box counting algorithm.
The problem of designing a search system in the Web resources which are accepted as reliable by experts and the problem of designing an adequate information retrieval system, are difficult to solve, in general. They a...
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