the representation of relevant information from volume data sets is a challenging task due to the high complexity of the structures and spatial features found in such data. the challenge is to represent such structure...
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ISBN:
(纸本)9798350364309;9798350364293
the representation of relevant information from volume data sets is a challenging task due to the high complexity of the structures and spatial features found in such data. the challenge is to represent such structures and features in a way that makes them easy to visually perceive without causing information overload in the resulting images. To this end, we propose a straightforward means of highlighting various regions from isosurfaces found in volume data, such that the visual perception of important surface details is improved. We use an approach based on curvature analysis to determine variations of the isosurface shape, allowing the accentuation of meaningful surface regions. We show that, while the resulting surface accents alone are enough to improve the display of surface details, combining our method with local illumination significantly contributes to a raised level of perception of the surface shape, as well as to the generation of more comprehensive representations of the underlying data. We present our results through illustrative images of medical CT volumes and perform an evaluation using several state-of-theart no-reference image quality assessment methods. Additionally, our technique does not require precomputation and is easy to incorporate into existing volume rendering engines.
Addressing control performance of the Permanent Magnet Synchronous Motor (PMSM) with sensorless controlsystems which use Field Oriented control (FOC), this paper proposes a control structure which uses a Super Twisti...
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ISBN:
(纸本)9798350364309;9798350364293
Addressing control performance of the Permanent Magnet Synchronous Motor (PMSM) with sensorless controlsystems which use Field Oriented control (FOC), this paper proposes a control structure which uses a Super Twisting-Terminal Sliding Mode control (ST-SMC) type control. Moreover, concerning the speed estimation for the PMSM rotor, the performance of a Sliding Mode Observer (SMO) type observer is improved by using a Phase Locked Loop (PLL) control technique. the control performance of the sensorless controlsystem is improved by optimally tuning the parameters of the ST-SMC controller using an Ant Colony Optimisation (ACO) algorithm. the control structures, observer and controller synthesis and proof of their convergence are also presented. Several computer simulations achieved in the Matlab/Simulink software environment demonstrate the superiority of the proposed sensorless PMSM controlsystem compared to the classical version. the performance criteria used for comparisons are classical indicators such as settling and rise time, speed signal ripple, stationary error, and Total Harmonic Distortion (thD).
this paper investigates the data-driven discovery of equations of motion for twin-tailed fighter aircraft, with a specific focus on addressing challenges posed by buffeting-induced vibrations in the F-15 model. Employ...
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ISBN:
(纸本)9798350364309;9798350364293
this paper investigates the data-driven discovery of equations of motion for twin-tailed fighter aircraft, with a specific focus on addressing challenges posed by buffeting-induced vibrations in the F-15 model. Employing the Sparse Identification of Nonlinear Dynamics (SINDy) algorithm, our research delves into the complexities of F-15 twin-tail dynamics. the utilized nonlinear model takes into account critical factors such as aerodynamic damping, cubic nonlinearities and intertail coupling. While the SINDy algorithm demonstrates promise in capturing the original dynamics, its sensitivity to wind disturbances prompts the application of the SINDYc algorithm. this enhanced approach accurately predicts system dynamics and provides valuable insights into effective control inputs. In this study we follow a step-by-step process, initially excluding wind disturbances to focus on intrinsic dynamics, followed by their introduction to assess adaptability. Coefficients derived from the system identification algorithm closely align withthe original synthetic data we generated using an existing model and the observed negligible error underscores the success of our data-driven methodology. this research contributes to advancing data-driven dynamics in aerospace engineering, providing an insight of how data-driven approaches could be utilized in the field.
the car suspension system has a major impact over the drivers' safety, since the public road might suffer various elevation changes and damage. this work focuses on finding optimal parameters of suspensions models...
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ISBN:
(纸本)9798350364309;9798350364293
the car suspension system has a major impact over the drivers' safety, since the public road might suffer various elevation changes and damage. this work focuses on finding optimal parameters of suspensions models, which are responsible for both safety and comfort of passengers while driving. We considered 4 different suspension architectures: 2-DOF, 3-DOF, 4-DOF quarter car and 5-DOF half car. these optimal configurations have been obtained using relatively recent proposed bio-inspired algorithms such as RDA, IRDA and MOGWO. All the simulations have been performed on different road profiles and different types of cars. Additionally, we propose 6 meta-optimization schemes called super-position (SP1 - SP6), that is to combine algorithms (RDA+MOGWO) in order to enhance the quality of the obtained configurations. the results show that the proposed super-position methods of RDA+MOGWO outperform previous similar methods, such as NSGA-II+SPEA2, by an increase of 3.44 % in quality.
A permanent magnet synchronous machine (PMSM) is considered in this paper in the presence of inductance saturation. the cascaded control structure consists of an inner and outer control loop. In the inner loop, a deco...
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ISBN:
(纸本)9798350364309;9798350364293
A permanent magnet synchronous machine (PMSM) is considered in this paper in the presence of inductance saturation. the cascaded control structure consists of an inner and outer control loop. In the inner loop, a decoupling structure is implemented. Two sliding mode controls (SMCs) are employed to robustify the current decoupling control. the combination of a decoupling controller (DC) and a SMC allows to obtain not only a desired sliding dynamics inside non-interacting controlled invariants but simultaneously a desired reaching phase dynamics that is characterized by the external dynamics of the subspaces. the decoupling approach allows to obtain a straightforward dynamics to be controlled. the presence of saturation, however, requires the identification of the quadrature inductance L-q. Otherwise, due to the huge impact of the current i(q) on this inductance, the control performance would decline. An identification of this variable allows to adapt the control structure properly. the identification is realized using an extended Kalman filter (EKF), where the maximum torque per Ampere (MTPA), SMC and DC are adapted using the estimated L-q values. the reference currents for the SMC controllers are determined by an MTPA strategy for the outer control loop. Here, the reference torque is calculated by the combination of geometric control and SMC. A robust control strategy with respect to the parametric and dynamic uncertainties is obtained withthe combination of SMC and EKF. Improvements in the performance of the controller are pointed out by dedicated computer simulations.
this paper addresses the problem of planning the motion of a mobile robot that has to visit some points of interest, each point having a specific time interval in which it can be reached. the robot is omnidirectional ...
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ISBN:
(纸本)9798350364309;9798350364293
this paper addresses the problem of planning the motion of a mobile robot that has to visit some points of interest, each point having a specific time interval in which it can be reached. the robot is omnidirectional and it evolves with constant speed in an environment cluttered with polygonal obstacles. In the case of no obstacles, the problem would be a Travelling Salesman Problem with Time Window (TSPTW) constraints. Our solution is innovative by enabling obstacles for TSPTW scenarios, and it accomplishes this by coupling visibility graphs, graph reduction and mathematical programming. the method first constructs a visibility graph based on the obstacles and points to be visited, and then it maps this graph to another graph whose nodes correspond only to robot's initial position and points of interest. Finally, a TSPTW problem is solved on the reduced graph by using a Mixed Integer Linear Programming (MILP) mathematical formulation, and the solution is projected to the initial environment. the solution development is accompanied by illustrative numerical simulations.
the skin lesion can be thought of as a biological system, so the morpho-granulometry of significant color clusters found in skin lesions is one of the elements that reproduce in a natural way the structure of the lesi...
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ISBN:
(纸本)9798350364309;9798350364293
the skin lesion can be thought of as a biological system, so the morpho-granulometry of significant color clusters found in skin lesions is one of the elements that reproduce in a natural way the structure of the lesion, this novelty is highlighted in this study. Important features of skin lesions can be modulated by fusing neural networks (NN) and machine learning (ML). By choosing the nevus and melanoma classes, the primary goal was accomplished, and three databases were used to test the methodology. the characteristics based on morpho-granulometry allowed for the identification of microstructure within the images, which can be very helpful in characterizing the biological system. Based on random forest (RF) and extreme gradient boosting (XGboost) classifiers, this work aimed to improve the classification performance of important feature selection. the selected features from three free image databases withthree NNs were classified. In a binary classification of nevus vs. melanoma, the results showed that the pattern recognition neural network (PRNN), according to the PH2 database, provided an accuracy of 0.923 and an F1-score of 0.876. the classification is interpretable if it is not validated. In our study, the best results were verified with a logistic regression (LR) classifier.
this paper presents a methodology for the design of a two-degree-of-freedom fractional-order PI controller (2-DoF FOPI) tuning rule for second-order plus dead-time (SOPDT) models. the methodology, which is based on Mo...
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ISBN:
(纸本)9798350364309;9798350364293
this paper presents a methodology for the design of a two-degree-of-freedom fractional-order PI controller (2-DoF FOPI) tuning rule for second-order plus dead-time (SOPDT) models. the methodology, which is based on Model Reference Robust Tuning (MoReRT), is intended to provide a robust and reliable approach to controller tuning. the optimization procedure to define the tuning rule is based on matching the response of the proposed controlsystem with target transfer functions defined from the servo and regulatory control modes of the system. this poses a design methodology that differs from that usually proposed for 2-DoF controllers. Furthermore, MoReRT enables the design of controllers with desired robustness levels within the range of typical values, which typically fall between 1.40 and 2.00 for the maximum value of the sensitivity function. To validate this proposed extension to the original methodology for integer controllers, an illustrative example is presented where the improvement in terms of controlsystem performance and robustness can be quantified.
this paper presents a RISC-V extension, called RiscDaqExt designed for Digital Acquisition and control over 32 individually managed digital channels. Each channel can be configured as input or output, inputs can be ne...
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ISBN:
(纸本)9798350364309;9798350364293
this paper presents a RISC-V extension, called RiscDaqExt designed for Digital Acquisition and control over 32 individually managed digital channels. Each channel can be configured as input or output, inputs can be negated or filtered before being recorded using specific masks and output channels source can be chosen between values given with a mask, result of a multi-signal operation on specified inputs or a PWM signal generated by the SigWavy extension. the extension is also capable of measuring PWMs frequencies and duty cycles. the extension is controlled using a dedicated ISA extension containing instructions for setting/getting configuration/values and for controlling the storing records of 32 signals values with 32-bit timestamps to an attached DDR3 memory or directly to hosting PC's RAM via Ethernet. the proposed solution, embedded into the RISC-V CPU named RiscDaq manages to initiate an Ethernet transmission of digital records 9.78x times faster than a MicroBlaze microcontroller, although our SoC operates with a 4x lower frequency, and outputs the result of logical operation performed over maximum 31 digital channels, with a constant 20 ns propagation delay, 49.2x times faster than a Cortex-M7 clocked at a 6x times higher frequency.
Recently, discussions on air pollution have escalated due to its harmful impact on human health. More and more often we meet a remarkable interest in air quality monitoring, the society we are living in is increasingl...
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ISBN:
(纸本)9798350364309;9798350364293
Recently, discussions on air pollution have escalated due to its harmful impact on human health. More and more often we meet a remarkable interest in air quality monitoring, the society we are living in is increasingly approaching methods of acquiring and installing weather and air quality monitoring stations in different locations, whether we are talking about urban or rural areas. While traditional air quality monitoring systems are slightly outdated and they have limitations in providing real-time data at a reasonable cost, technological advances such as the Internet of things (IoT) offer promising solutions for efficient monitoring in terms of costs, time and energy consumption. thus, currently smart cities manage to successfully integrate both hardware and software devices to establish complete air quality monitoring systems. this paper proposes an extensive state-of-the-art and a synthesis on the environmental parameters and the air quality index obtained through certain current methods of air quality monitoring. To overcome today's pollution monitoring systems drawbacks, the air quality index (AQI) was defined according to EU and World Health Organization standards. the AQI was computed based on three different databases in a proposed online application for pollution monitoring and analysis. the calculation method of AQI with existing monitoring systems was compared with current standards AQI for a clear and uniform view of air quality.
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