12 research outputs found
Sliding mode control of discrete-time weakly coupled systems
No full textSliding mode control is a form of variable structure control which is a powerful tool to cope with external disturbances and uncertainty. There are many applications of sliding mode control of weakly coupled system to absorption columns, catalytic crackers, chemical plants, chemical reactors, helicopters, satellites, flexible beams, cold-rolling mills, power systems, electrical circuits, computer/communication networks, etc. In this thesis, the problem of sliding mode control for systems, which are composed of two weakly coupled subsystems, is addressed. This thesis presents several methods to apply sliding mode control to linear discretetime weakly-coupled systems and di fferent approaches to decouple the sub-systems. The application of Utkin and Young's sliding mode control method on discrete-time weakly-coupled systems is studied in detail which is then compared with other control algorithms while emphasizing the importance of the decoupling technique in each case. It also presents the possibility of integrating two or more control strategies for a single system; one for each sub-system, depending upon the respective requirements and constraints. In this thesis, the eff ectiveness of the proposed methods is demonstrated through theory and simulation results.M.S.Includes bibliographical referencesIncludes vitaby Prashanth Kumar Gopal
Transmission Line Parameter Estimation using Synchrophasor Data
Get PDFabstract: Transmission line parameters play an important role in state estimation, dynamic line rating, and fault analysis. Because of this, several methods have been proposed in the literature for line parameter estimation, especially using synchrophasor data. However, success of most prior research has been demonstrated using purely synthetic data. A synthetic dataset does not have the problems encountered with real data, such as invariance of measurements and realistic field noise. Therefore, the algorithms developed using synthetic datasets may not be as effective when used in practice. On the other hand, the true values of the line parameters are unknown and therefore the algorithms cannot be directly implemented on real data. A multi-stage test procedure is developed in this work to circumvent this problem.
In this thesis, two popular algorithms, namely, moving-window total least squares (MWTLS) and recursive Kalman filter (RKF) are applied on real data in multiple stages. In the first stage, the algorithms are tested on a purely synthetic dataset. This is followed by testing done on pseudo-synthetic datasets generated using real PMU data. In the final stage, the algorithms are implemented on the real PMU data obtained from a local utility. The results show that in the context of the given problem, RKF has better performance than MWTLS. Furthermore, to improve the performance of RKF on real data, ASPEN data are used to calculate the initial estimates. The estimation results show that the RKF algorithm can reliably estimate the sequence impedances, using ASPEN data as a starting condition. The estimation procedure is repeated over different time periods and the corresponding results are presented.
Finally, the significance of data drop-outs and its impact on the use of parameter estimates for real-time power system applications, such as state estimation and dynamic line rating, is discussed. To address the problem (of data drop-outs), an auto regressive integrated moving average (ARIMA) model is implemented. The ability of this model to predict the variations in sequence impedances is demonstrated.Dissertation/ThesisMasters Thesis Electrical Engineering 201
Design and Fabrication of Jilebi Making Gadget
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Effect of pore size distribution and particle size of porous metal oxides on phosphate adsorption capacity and kinetics
No full textPhosphate is a vital nutrient but its presence in surface waters even at very low concentrations can lead to eutrophication. Adsorption is often suggested as a step for reducing phosphate down to very low concentrations. Porous metal oxides can be used as granular adsorbents that have a high surface area and hence a high adsorption capacity. But from a practical point of view, these adsorbents also need to have good adsorption kinetics. The surface area of such adsorbents comes from pores of varying pore size and the pore size distribution (PSD) of the adsorbents can affect the phosphate adsorption kinetics. In this study, the PSD of 4 different adsorbents was correlated with their phosphate adsorption kinetics. The adsorbents based on iron and aluminium (hydr)oxide were grinded and the adsorption performance was studied as a function of their particle size. This was done to identify diffusion limitations due to the PSD of the adsorbents. The phosphate adsorption kinetics were similar for small particles of all the adsorbents. For larger particles, the adsorbents having pores larger than 10 nm (FSP and DD6) showed faster adsorption than adsorbents with smaller pores (GEH and CFH). Even though micropores (pores < 2 nm) contributed to a higher portion of the adsorbent surface area, pores bigger than 10 nm were needed to increase the rate of adsorption.Accepted Author ManuscriptBT/Environmental Biotechnolog
Building on Communities to further Software Sustainability
No full textTalk given as part of SIAM Conference on Computational Science and Engineering 2023 Session "MS282 Towards Improvement of Sustainability and Productivity for Research Software - Part II of II"
The author would like to thank the contributions from
Alok Kumar Gupta, Elina Miinalainen, Hamish Struthers, Jean Iaquinta, Kimmo Ervasti, Maiken Pedersen, Oskar Landgren, Øyvind Seland, Prashanth Dwarakanath, Risto Makkonen, Tommi Bergman, Tyge Løvseth, Yanchun He
Software sustainability is increasingly recognised as a must in scientific research. Well-established tools for source code management, for software package (and dependency) management and/or application-level virtualisation (containerisation) are often instrumental in the development of software. No matter how “good” these tools are, alone they can hardly ensure long-term sustainability. Teams and communities are equally or even more important than any technical solution chosen. Building community practices to ensure the long-term sustainability of software is rarely given priority in the context of scientific projects which heavily rely on them nonetheless. Co-developing “best practices” with communities proves to lead to a wider/better adoption, more efficient work/developments, higher quality documentation and training material/tutorials, a much flatter learning curve which makes it easier onboarding newcomers, and all that translates into a better take up by researchers. In this talk, the Nordic Infrastructure Community for Earth System Modelling Tools will explain how they have placed people at the centre of the software development cycle to ensure its long-term sustainability. Successful examples will be presented as well as failures, to highlight what went well or wrong, respectively, and why. The importance of going beyond its own team and community will be discussed as well as how to think about a scientific project in a wider context e.g Open Science.This work was produced for the NeIC NICEST2 project, that is supported by the Nordic e-Infrastructure Collaboration (NeIC), which is part of NordForsk
Understanding and improving the reusability of phosphate adsorbents for wastewater effluent polishing
No full textPhosphate is a vital nutrient for life but its discharge from wastewater effluents can lead to eutrophication. Adsorption can be used as effluent polishing step to reduce phosphate to very low concentrations. Adsorbent reusability is an important parameter to make the adsorption process economically feasible. This implies that the adsorbent can be regenerated and used over several cycles without appreciable performance decline. In the current study, we have studied the phosphate adsorption and reusability of commercial iron oxide based adsorbents for wastewater effluent. Effects of adsorbent properties like particle size, surface area, type of iron oxide, and effects of some competing ions were determined. Moreover the effects of regeneration methods, which include an alkaline desorption step and an acid wash step, were studied. It was found that reducing the adsorbent particle size increased the phosphate adsorption of porous adsorbents significantly. Amongst all the other parameters, calcium had the greatest influence on phosphate adsorption and adsorbent reusability. Phosphate adsorption was enhanced by co-adsorption of calcium, but calcium formed surface precipitates such as calcium carbonate. These surface precipitates affected the adsorbent reusability and needed to be removed by implementing an acid wash step. The insights from this study are useful in designing optimal regeneration procedures and improving the lifetime of phosphate adsorbents used for wastewater effluent polishing.</p
Effect of pore size distribution on iron oxide coated granular activated carbons for phosphate adsorption – Importance of mesopores
No full textAdsorption is often suggested for to reach very low phosphate levels in municipal wastewater effluent and even to recover phosphate. Adsorbent performance is usually associated with surface area but the exact role of the pore size distribution (PSD) is unclear. Here, we show the effect of the PSD on phosphate adsorption. Granular activated carbons (GACs) with varying PSDs were treated with potassium permanganate followed by reaction with ferric chloride to form iron oxide coated GACs (Fe-GACs). Energy dispersive X-ray and kinetics experiments confirmed that manganese anchored on the GAC is important for subsequent iron attachment. Mössbauer spectroscopy showed presence of ferrihydrite in Fe-GAC. Transmission electron microscopy showed that the iron oxide particles are not present in the micropores of the GACs. Phosphate adsorption isotherms were performed with the Fe-GACs and adsorption at lower phosphate concentrations correlated with the porous area of >3 nm of the adsorbents, a high fraction of which is contributed by mesopores. These results show that high surface areas of GACs resulting from micropores do not contribute to adsorption at low phosphate concentrations. This can be explained by the micropores being difficult to coat with iron oxide nanoparticles, but in addition the diffusion of phosphate into these pores could also be hindered. It is therefore recommended to use backbones having high mesoporous areas. This information is useful for developing adsorbents particularly for applications treating low phosphate concentrations, for e.g. in municipal wastewater effluent polishing
Effects of preparation methods on inherent fabric anisotropy and packing density of reconstituted sand
No full text© 2018, © 2018 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license. This paper investigates the effects of different preparation methods (dry tamping, moist tamping, dry pluviation and wet pluviation) on inherent fabric anisotropy of reconstituted sand samples in the laboratory. An image analysis approach was used to quantify the inherent fabric anisotropy in terms of the vector magnitude based on a second-order fabric tensor. In addition, the effects of reconstituted soil sample preparation methods on the void ratio and density index were investigated. This study shows that the specimens prepared by pluviation methods possess more pronounced inherent fabric anisotropy than those by tamping methods. Among all the methods considered in this investigation, the dry pluviation method provided the highest degree of inherent fabric anisotropy. It is shown that the mass-flow and drop height does not effectively influence the packing density. Also, it has been found that no significant effect on void ratio is observed while using different tamping methods, which may be attributed to the fact that the sand used in this study is less well graded. In addition, it is found that the increase in the height of tamper leads to an increase in packing density or a decrease in relative density, with an approximately linear relationship
Demographic and Clinical Profiles of Parkinson's Disease in India:Observations from a Nation-Wide Multicenter Study
Get PDFBACKGROUND: Parkinson's disease (PD) phenotype may vary with genetic, ethno-geographic, cultural, and environmental factors.OBJECTIVES: The aim was to develop a clinical database of PD in India and assess the influence of age-at-onset (AAO), gender, and motor subtype on the clinical profile of PD.METHODS: A cross-sectional study of PD was conducted across 18 Indian hospitals. Standardized assessments were performed by movement disorder specialists. Data were collected using uniform questionnaires during the recruitment visit. A total of 3300 age- and gender-matched case-control pairs were analyzed for environmental exposures, habits, and co-morbidities.RESULTS: We recruited 7918 PD cases with a mean AAO of 54.2 ± 11.8 years and a median disease duration of 5 years (interquartile range: 2-9). Subgroup analyses based on AAO, gender, and motor phenotype revealed significant differences in motor and non-motor symptoms, exposures, habits, and co-morbidities. Except coffee consumption, previously known associations were observed for exposure to insecticides/pesticides/fungicides (odds ratio [OR]: 1.67), head injury (OR: 3.11), coffee consumption (OR: 1.73), diabetes (OR: 1.48), hypertension (OR: 1.73), and smoking (OR: 0.74) in the Indian population.CONCLUSIONS: This large pan-Indian study highlights the clinical characteristics, environmental exposures, habits, and comorbid diseases associated with PD, which were broadly similar to those observed in European populations. The earlier AAO in Indian PD patients suggests a potentially higher genetic risk, warranting further investigation. A nationwide, community-based, epidemiological study is needed to achieve a comprehensive understanding of all risk factors for PD in India and to validate the risk factors identified in this hospital-based study. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.</p
