22 research outputs found
Improved Mean Variance Mapping Optimization for the Travelling Salesman Problem
No full textThis paper presents an improved Mean Variance Mapping Optimization to address and solve the NP-hard combinatorial problem, the travelling salesman problem. MVMO, conceived and developed by István Erlich is a recent addition to the large set of heuristic optimization algorithms with a strategic novel feature of mapping function used for mutation on basis of the mean and variance of the population set initialized. Also, a new crossover scheme has been proposed which is a collective of two crossover techniques to produce fitter offsprings. The mutation technique adopted is only used if it converges towards more economic traversal. Also, the change in control parameters of the algorithm doesn’t affect the result thus making it a fine algorithm for combinatorial as well as continuous problems as is evident from the experimental results and the comparisons with other algorithms which has been tested against the set of benchmarks from the TSPLIB library.</p
Design and experimental validation of robust PID control for a power converter in a DC microgrid application
No full textIn a DC microgrid, power electronic DC-DC converters are interfaced with DC loads that pose a stringent requirement of maintaining constant DC output voltage across the load terminals. In particular, the problem of controlling the load voltage of nonminimum phase (NMP) DC-DC boost converter with the measured load voltage under voltage mode control (VMC) is addressed. This control problem is challenging due to NMP dynamics and restricts the achievable bandwidth in the closed-loop operation. To improve the closed-loop performance of NMP boost-type converter against the disturbances (external) and uncertainty in DC microgrid environment, the Quantitative feedback theory (QFT) is used to synthesize a robust PID controller systematically. The merits of the proposed robust PID design procedure using QFT are as follows: (i) it does not require any tuning of the PID values unlike in the conventional PID design which heavily depends on the ad-hoc tuning, (ii) the dynamics of the disturbance (load current and input voltage variations) are accounted in the synthesis stage that further improves the disturbance effect minimization on the load voltage response, and (iii) the simple, straight forward design of the right half plane zero of boost-type DC-DC converter with the bandwidth limitations. The proposed design is illustrated extensively using the simulation with the external disturbances and demonstrated its advantages over a conventional PID. Finally, under various regulatory scenarios, experiments are performed to validate the simulation of the proposed PID design without retuning the controller parameters. The superior dynamic performance of the proposed PID is delineated in experimental results and provides more robustness in different scenarios as compared to the conventional PID
Application of Genetic Fuzzy System for Damage Identification in Cantilever Beam Structure
No full textAbstractThe performance of the system consisting of beam structures is very much affected by identification of faults or damage in it's structural integrity. The consistent and secure operation can be well ensured in an engineering system by effectively identifying the damage in the structures. The conventional techniques are rendered to few limitations due to the unreliable mathematical simulation used for actual scenario. Therefore, hybrid artificial techniques (AI) would be more sophisticated tool for damage identification in beam structures. The combination of Fuzzy inference system and Genetic algorithms (GAs) can be employed to obtain effective solutions for many systems. In the current research, GA-Fuzzy controller has been considered for identification of damage in steel cantilever beam in transverse direction subjected to natural vibration. The results obtained from the proposed technique have been in very good agreement with the experimental results
A Cosine Similarity-Based Centralized Protection Scheme for DC Microgrids
No full textUnlike the phasor measurement-based protection in AC systems, the protection of DC systems deals with complex fault transients which mandates the isolation of the faulted segment within few milliseconds as continued fault current leadsto overheating issue in power electronic converters. To this end, several works have been suggested based on unit and non-unit protections for DC microgrids. Threshold selection and protection coordination are the challenges associated with non-unit protection. Similarly, communication delay and link failure limit the application of unit protection. To address these issues, this paper presents a robust centralized protection scheme for DC microgrids, which is resilient to communication delay and link failure. It uses current of each line segment to compute the similarity of current change at both ends of the line segment to derive the protection decision. To overcome the communication failure from one end of the line segment or even from multiple segments, the proposed method uses data from adjacent segments to derive the protection decision correctly.Using PSCAD/EMTDC environment, the performance of the proposed method is evaluated for various cases and compared with available techniques. Finally, the accuracy of the protection algorithm is validated under experimental conditions
Design and Performance Analysis of an IoT Based Health Monitoring System for Hospital Management
No full textShort-chain n-alkanes in benthic mats and mosses from the Larsemann Hills, East Antarctica
No full textVariation in leaf colour (green, red and grey) of mosses and lake benthic mats in Antarctica is often linked to water stress and ultraviolet light (UV-B) exposure. Changes in the abundance of organic compounds, such as pectin and phenols, are associated with mechanisms protecting against desiccation and UV radiation. However, the function of n-alkanes, especially against UV radiation, is rarely examined. Here, gas chromatography–mass spectrometry and Fourier-transform infrared spectroscopy analyses were performed to study the variation in n-alkanes in freshwater lake benthic mats and mosses collected from the Larsemann Hills in East Antarctica. Stable isotopes of organic carbon and nitrogen, environmental DNA characterisation and microscopy-based analyses are used to estimate the presence of cyanobacteria, algae and diatoms in moss and benthic mat consortia. Variation in the short-chain (n-C17 to n-C20) versus long-chain (n-C21 to n-C30) n-alkanes in the mosses and benthic mats with their colour were noted. The research links the relative abundance of short-chain n-alkanes to the UV-B exposure and proposes that Antarctic mosses and benthic mats synthesise short-chain n-alkanes for protection against UV-B.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Sanitary Engineerin
An Overview of Fully Integrated Switching Power Converters Based on Switched-Capacitor versus Inductive Approach and Their Advanced Control Aspects
No full textThis paper reviews and discusses the state of the art of integrated switched-capacitor and integrated inductive power converters and provides a perspective on progress towards the realization of efficient and fully integrated DC–DC power conversion. A comparative assessment has been presented to review the salient features in the utilization of transistor technology between the switched-capacitor and switched inductor converter-based approaches. First, applications that drive the need for integrated switching power converters are introduced, and further implementation issues to be addressed also are discussed. Second, different control and modulation strategies applied to integrated switched-capacitor (voltage conversion ratio control, duty cycle control, switching frequency modulation, Ron modulation, and series low drop out) and inductive converters (pulse width modulation and pulse frequency modulation) are then discussed. Finally, a complete set of integrated power converters are related in terms of their conditions and operation metrics, thereby allowing a categorization to provide the suitability of converter technologies
