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Synthesis of Enesulfonamides and Benzoxazolidines through Transition-metal Catalyzed C-N Bond Formation
No full textOwing to the ubiquity of carbon-nitrogen bond in numerous functional materials, natural products and pharmaceutical agents, the construction of such bonds has been emerged as a frontier area in organic synthesis. In recent years, the transition metal mediated C-C and C- heteroatom bond formation reaction have opened a new avenue with regard to efficiency and versatility. Though, extensive progress in this field has been made, still the formation C-C and C- heteroatom bond, particularly at the unactivated C(sp2) centers is challenging. Notably, the majority of transition-metal-mediated coupling reactions rely on the use of nucleophilic substrates that are prefunctionalized with organometallic traceless activation groups (e.g., boronic acids, stannanes, zinc reagent, and grignard reagent). However, an ever-increasing impetus to improve the versatility, cost, and operational simplicity of transition-metal-based methods has led to the development of elegant protocols that employ organic, native functionality as activation handles for complex fragment coupling reactions. The Fujiwara- Moritani reaction, reported in 1967, is apparently the first representative Pd-catalyzed coupling reaction for C−H alkenylation of arenes. Since then, adequate progress has been made for the transition metal catalyzed C-C and C-heteroatom bond formation reactions by using various unfunctionalized olefines. In turn, the N-alkenylation of amines and amides leading to biologically potent enamines and enamides, respectively, has been investigated extensively. In contrast, skimpy efforts have been made for the N-alkenylation of sulfonamides, although the resulting enesulfonamides are not only privileged as pharmaceutical compounds, but also serve as highly versatile synthetic intermediates, especially in the formation of heterocycles such as saturated oxazolidines, imidazolidines, piperidines, alkaloids and in asymmetric synthesis to access a wide variety of functional benzenesulfonamides. Additionally, the reported methods on enesulfonamide synthesis mainly embark the synthesis of E-enesulfonamides. There are only two methods including the use of Ir- and Rh-catalyst have been developed to access the Z- enesulfonamides from the azides and triazoles respectively. As such, the synthesis thermodynamically unfavorable Z–enesulfonamide is challenging.
In this context, our recent efforts toward the transition metal catalyzed C-N bond formation leading to the stereoselective synthesis of Z-enesulfonamides have been described in this thesis. Furthermore, a novel protocol for the synthesis of benzoxazolidines via enesulfonamide intermediate was also described. The current thesis entitled “Synthesis of Enesulfonamides and Benzoxazolidines through Transition-metal Catalyzed C-N Bond Formation” has been divided into five chapters. A summary of the chapters are as follows:
Chapter 1. Synthesis and Reactions of Enesulfonamides: A Brief Overview
In this chapter we have described the various methods of enamide and enesulfonamide synthesis. Scope and limitations of the earlier works along with the objective of the present work on enesulfonamide and benzoxazolidine synthesis through C-N bond formation have been presented.
Chapter 2. Stereoselective Synthesis of Enesulfonamides via Pd-catalyzed Oxidative Sulfamidation of Terminal Alkenes
This chapter describes the development of a novel catalytic protocol for the synthesis of Z- enesulfonamides by the oxidative sulfamidation of olefins in the presence of ambient air. This protocol is also found to be suitable for the cross coupling of sterically hindered secondary sulfonamides with electron deficient olefins leading to E-enesulfonamides in good yield.
Chapter 3. Palladium-Catalyzed Oxamidation of Alkenes: A New Approach to Benzoxazolidines
This chapter reveals the palladium catalyzed protocol for the synthesis of benzoxazolidine by the reaction of sulfamidophenol and electron deficint terminal alkene. This oxamidation process is simple and does not require any ligand, base or inert atmosphere for the overall transformation.
Chapter 4. Synthesis of benzoxazolidines via Ni-catalyzed Deacylative Oxosulfonamidation of Vinyl acetate
In this chapter Ni-catalyzed a simple and efficient method for the synthesis of benzoxazolidines from the reaction of sulfonamidoalcohol and electron rich alkenes was reported. Subsequently in-situ halofunctionalization was also performed in the presence of Ni-catalyst and a halogen source.
Chapter 5. Conclusion and Future scopes
In the last chapter, the overall conclusions and future scopes of the present work have been described
Monitoring and Prediction of Fugitive Dust Concentration in Mechanized Opencast Coal Mine
No full textAtmospheric pollution due to particulate matter (PM) in opencast coal mining area is a very critical environmental issue. Nowadays in India, around 92% of the coal is produced by opencast mining method, which generates huge quantities of respirable PM by the processes like drilling, blasting, transportation, loading, unloading and mine fires. Further, mechanization in mines lead to add a heavy load of PM to the surrounding area. The particulate matter not only affects the human but also have tremendous effects on nearby flora and fauna by degrading the ecological environment in many ways. Most of the pulmonary diseases related to air pollution are generally directly or indirectly related to the physical and chemical characteristics of respirable PM (PM10). The monitoring and evaluation of PM concentration is the first important step in controlling PM level. So it becomes necessary to characterize the PM along with the monitoring for better source management.
This thesis mainly focuses on the measurement and characterization of respirable PM in and around a mechanized opencast coal mine of Talcher coalfields, Odisha. The study was carried out for a period of one year from March 2015 to February 2016, and seasonal variations of PM concentration was studied. The monitoring of particulate concentration revealed that the concentration of both PM10 and PM2.5levels were far above the standard limit of NAAQS, 2009. The trace metal study by atomic absorption spectrophotometer (AAS) indicated the presence of high concentration of Cd in the study area with Hg and Se. The concentration of Ni and As was found above the NAAQS, 2009 at most of the stations. The source apportionment study by using statistical techniques suggested the dominance of Cu, Pb, Cd, and As in PM10 of the study area indicated vehicular emission, coal transportation, coal burning, running of mine machineries, and windblown earth crust material were the principal sources of PM pollution. The correlation analysis supported the relationship between different parameters. Qualitative analysis was performed using FTIR, and XRD. The FTIR study showed the presence of different functional groups like hydroxyl, methyl, carboxylate, aldehyde, inorganic carbonate, sulphonate etc. in the PM10 with strong mineral bands of quartz, kaolinite, sepiolite, cerussite and nacrite at all the stations. The study from the XRD analysis of the PM10 samples showed that minerals such as Kaolinite, gypsum, siderite, quartz, hematite, illite, and dolomite were the most common minerals found in the PM10 in all the samples of the study area. Quartz was detected as dominated mineral. Secondary found minerals containing heavy metals like claudetite, mimetite, morenosite, and tiemannite were detected in the study area in trace amount. The health risk was calculated for the people residing near to the mining area due to presence of quartz in respirable air and found above the standard limit at most of the stations. The health risk was also assessed from the trace metals for both children and adults. The excess cancer risk (ECR) for children and adults were estimated to evaluate the cancerous risk due to individual as well as combined effects of metal (ECR Total). The HQ values for Cr and Cd were found above the safe limit in that area for both children and adults. Likewise the ECR values for Cr and Cd also were at a very risk level for both the age group. The HI and ECRTotal values were found above the safe limit which indicate the combine effect of trace metal on the children and adult were at a very high risk level in the study area. Finally AERMOD software was used to predict the PM concentration at different receptor locations and compared with the observed PM concentration to calculate the baseline concentration of PM in the study area. Further by using the model different locations were identified around the mine having PM concentration above NAAQS, 2009
A Flood Mitigation Strategy for Floodplain Areas in India
No full textFlooding is one of the most common natural disasters in India and this phenomenon has been worsening due to current global warming condition. The disaster cost the government a huge amount of money and effort to handle it in terms of its catastrophe and mitigation strategy. It also has an adverse effect on land value in the floodplain area. In India, more than 40 Million Hectare of the total 329 Million Hectare geographical area is flood prone. During last three decades, other than heavy financial losses, millions of people were affected and about 4000 people lost their life due to the flood disaster in India. Therefore, it is crucial to resort for more effective flood mitigation approach in India. This need has motivated this research to develop a new sustainable and flexible flood mitigation measure known as amphibious house system within a floating urbanisation environment. This concept enabled the dwellers to live with flood rather than to confront it. The amphibious house system consists of the pit system concept with horizontal support, an efficient amphibious foundation system and special designed vertical guidance system, which provide floatation to the house during flooding. This amphibious house is designed with a rainwater harvesting and storage system which gives easy access to clean water to the residents of the house. This house is also integrated with solar panels, to give free electricity to the residents. This house has a composting toilet which eases the dependency on the sewage system provided by the administration. Basically this house is designed for poor class people of India to ease their dependence on the public water supply, electricity and sewage system
Investigation and Optimization of Plasma Arc Cutting Process
Get PDFHigh strength materials are most widely used in producing the parts of military, automobile, marine and mining industries. Special abrasion resistance material is used for above industries because of their superior mechanical properties like good weld capacity, good bendability, higher toughness and better workability. These alloy materials are classified as “Hard-to-cut” type materials and very difficult to cut the work piece. Cutting of high abrasion resistance alloy material with better dimensional accuracy in faster cutting speed within economic cost is still a challenging task for manufacturing industries. Generally fabrication units employed plasma arc cutting machine to cut the high strength material due to its advantages over the other cutting processes. The correct selection of machining parameter and plasma gas is very important for smooth cutting with high precision. The optimization of input parameters reveals the proper machining condition for cutting process. In addition to that, it was also noticed that the selection of appropriate plasma gas could enhanced the cutting process. Therefore, in the first stage of the research work, Investigation and optimization of plasma arc cutting process using different optimization techniques of some high strength and high abrasion resistance alloy material which was not sufficiently addressed so far were carried out. A CNC plasma arc cutting machine of MESSER industry named (BURNY 1250) was used to conduct the experiment of sailhard steel, abrex 400 steel and hardox 400 steel. These alloy materials have superior mechanical properties for manufacturing the parts of mining, automobile, petrochemical, oil and natural gas industries. On the other hand, a portable laboratorial plasma arc cutting machine was employed to investigate and optimize the cutting operation of 304L stainless steel. This alloy material has mostly employed for household and commercial application because of its superior corrosion resistance in nature. The cutting parameters were selected as cutting current, gas supply pressure, cutting speed, stand-off-distance and feed rate were selected as cutting parameter. Surface roughness, material removal rate, kerf, chamfer and dross were considered as output responses. Taguchi’s orthogonal array was taken to design the run of experiment during cutting process. Additionally, three different multi criteria decision making techniques viz. Desirability approach, Technique for order of preference by similar to ideal solution (TOPSIS) and Vlsekriterijumska optimizacija KOm-promisno Resenje (VIKOR) were suggested to attain optimal cutting condition in order to minimize the production cost and maximize the productivity without compromising the quality. Also, a prediction model was developed to estimate the responses using multiple regression analysis (MRA). A comparison between experimental and predicted result shows the accuracy of the model. An ANOVA test was established to evaluate the significance of process parameter. Finally, a confirmation test was obtained to show the degree of effectiveness of proposed method. The optimum setting of process parameters will offer a very good cutting condition in order to achieve the preciseness.
In the second stage, an experimental analysis was carried out to observe the effect of different plasma gas on the work piece material during plasma arc cutting process. The influence of flow rate of plasma gas on the plasma arc cutting process was investigated. Four different plasma gases were selected for this experiment viz. air, argon, oxygen and nitrogen. The thermo physical properties of plasma gases, properties of generated arc, cutting performance and energy balance was explained for different plasma gases. This research work was also clarified the potential of cutting process by varying the flow rate and chemical composition of the plasma gas.
Finally, a temperature analysis was developed over the surface of work piece during plasma arc cutting process. The moving heat source was taken into consideration for calculation the heat created by plasma arc. The heat of fusion was also considered for estimation due to molten layer separates the plasma and solid layer. Different thickness of molten layer were taken for calculation viz. zero thickness, 10% and 20%. The estimated results are shown in non-dimensional form. So, the method can be applied for any other types of material
Payment Methods and Shareholders’ Gains in Mergers and Acquisitions: An Empirical Investigation into Indian Companies
No full textPurpose
Mergers and Acquisitions (M&A) are an essential corporate growth strategy to survive in this competitive world. The primary objective of this study is to examine the determinants of the payment methods (cash, stock, mixed) of M&A and also to find out the impact of the M&A announcement on the short-term stock performance of the Indian non-financial acquirer companies. This study aims to identify the trends of payment methods of M&A used by companies from top ten M&A leading countries with special attention to India. The study observes the short-term stock performance of the Indian acquiring companies due to the announcement of different payment methods in M&A deals. The study investigates the Indian acquiring company’s stock performance due to the announcement of different types of deals as per the listing status of the target firm, industry relatedness and the acquired stake in M&A deals.
Methodology
To carry out this empirical study, secondary data relating to M&A deals were collected from Bloomberg database, Centre for Monitoring Indian Economy (CMIE) Prowess IQ Database and information relating to stock price was collected from Bombay Stock Exchange (BSE) website. The study covers the M&A deals that are announced by acquirer from the non-financial sector in India from April 1, 2000 to March 31, 2017 for the empirical analysis. To achieve different objectives, different statistical tools and techniques such as histogram, pie chart, descriptive statistics, independent sample t-test and logistic regression were used. Event study methodology was applied based on the market model with a different event window to investigate the stock returns during the M&A announcement period. Parametric test (Patell z) and a non-parametric test (sign test) were used to check the robustness of the results.
Findings
The results of the study indicate that the payment methods of M&A deal in non-financial companies are significantly affected by the characteristics of acquirer, target, and deal respectively. It is found that there is a positive relationship between the acquirer’s cash availability, percentage of promoter holdings in acquirer company and acquirer’s collateral with cash as a mode of payment in Indian M&A deals. It also appears that the determinants like deal value, acquirer’s leverage, target firm’s listing on the stock exchange and target industry relatedness are negatively related to M&A deals done with the cash payment method. The results also specify that Indian acquirers’ stock returns are positively higher in the pre-announcement period for cash and mixed payment methods deals than stock payment method. The result also shows that in the stock payment method, the stock returns are negative in various window periods across the announcement day. The cumulative average abnormal return is higher in case acquirer and target are in the same industry than unrelated industry. The acquirer earns more stock returns in case of complete stake acquisitions of the target than majority stake acquisitions. The study also shows that the acquisition of unlisted targets creates higher announcement-period returns than the acquisition of listed targets.
Implications
The knowledge gained from this study will help managers from both acquirer and target companies for selection of appropriate payment method in different corporate situations and improve their investment mechanism and strengthen their finances by value creation in M&A. Therefore, this can optimise their cost of capital in both pre and post-acquisition period. This study also helpful for the shareholders and short-term investors to generate wealth during the M&A announcement.
Originality
Most of the studies relating to determinants of payment methods and shareholders’ gains in M&A have concentrated mainly developed countries. Briefly examining the determinants of payment methods and validating the payment methods hypothesis in an emerging market like India, by taking large sample period is an original move in this study. The study adds to the existing literature by evaluating the impact of various important factors of M&A; such as payment methods, industry relatedness, listing status of the target firm and the percentage of stake acquired on the short-term stock performance of Indian acquirer
Nonlinear Thermoelastic Analysis of Graded CNT-Reinforced Sandwich Structure Embedded with SMA Fibre- Theoretical and Experimental Verification
No full textThe nonlinear thermoelastic behavior of the graded nanotube reinforced sandwich panel structure bonded with and without shape memory alloy (SMA) fibre is computed numerically using a generic micromechanical model. Further, the solution accuracy has been verified with those available published data and own experimental test values. For the numerical analysis purpose, the graded nanotube sandwich structural model is derived mathematically using a higher-order polynomial kinematics and Green-Lagrange nonlinear strain including the influences of variable temperature profile (uniform and linear). Also, the material nonlinearity of SMA fibre due to the elevated thermal environment is included in the micromechanical model through the marching technique. Additionally, the model generality has been maintained by adding all of the nonlinear higher-order mid-plane strains in the formulation part. The individual properties of the reinforcement (nanotube), matrix and the functional materials (SMA) are assumed to be temperature dependent. The numerical responses are obtained through a suitable customized computer code (developed in MATLAB environment) with the help of currently derived higher-order micromechanical model. Moreover, the convergence of the finite element solution including the correctness has been confirmed via solving different kinds of numerical examples. The results are compared with available published data obtained either numerically or exact solution techniques. Also, the responses are compared with own experimental data for the few specific cases i.e. vibration and linear/nonlinear bending values of the composite/sandwich structures. In addition, the commercial finite element package (ANSYS) also utilized to model the graded nanotube structure and the sandwich panel via the batch input technique (ANSYS parametric design language code) for the evaluation of desired responses. Finally, the influences of variable design input parameters (thickness ratio, aspect ratio, type of geometry, support at the edges, curvature ratio and temperature) on the nanotube-reinforced composite/sandwich structural responses embedded with and without functional materials (SMA volume fractions, prestrain values and temperature loading) are explored by solving different kinds of numerical example including the effect of the nanotube grading configurations and temperature dependent properties
Distributed Secondary Control Schemes for Islanded Microgrid
No full textNowadays, electrical grids are made more intelligent, distributed and responsive. A microgrid is a small-scale modern power system that facilitates integration of Distributed Generators (DGs) such as photovoltaics, and wind turbine, local loads and energy storage units. Microgrids ensure the local power quality, safety and also prevent the grid from occurrence of unexpected harmful disturbances due to the intermittent nature of Renewable Energy Sources (RES). A microgrid can operate in both grid-tied mode and islanded mode in the event of preplanned scheduling or disturbances. In the grid-tied mode of operation, the voltage and frequency are governed by the main grid. In the islanded operating mode, control becomes more challenging due to the low equivalent inertia of RES, varying load demand, and uncertainty of DGs output. Microgrid control can be broadly categorized into hierarchical structure, in which the first level is primary droop control, which is locally implemented. It stabilizes the MG operating voltage and frequency after islanding. However, primary control leads to system voltage and frequency deviations from their nominal values. The second hierarchical level is the secondary control that compensates for the deviations caused by the primary control. Tertiary control is responsible the for global cost, and power flow optimization. It also regulates the power exchange from an external grid or with other microgrids.
This thesis primarily deals with a comprehensive distributed secondary control Strategies of an autonomous AC microgrid system modeled as a multi-agent system. The distributed structure avoids the necessity of a centralized control structure and complex bi-directional communication network, thereby improving reliability, scalability, and eliminate the risk of single-point-failure. The main secondary control objectives are microgrid voltage and frequency restoration and, accurate active and reactive power-sharing among the distributed generators. The asymptotic controllers limit the convergence performance and they are not suitable for fast-changing operating conditions. Therefore, a special emphasis is given to the finite-time convergence control approaches to achieve faster and flexible settling time for secondary control. The proposed control methodologies are fully distributed and each distributed generator communicate with their immediate neighbors for information sharing via a sparse communication network. The loss of communication link does not affect the controller performance much until the communication graph remains connected. Further, the proposed control schemes are scalable and support the important features such as scalability and plug and play operation of a microgrid system.
A dynamic average consensus-based distributed control scheme is proposed for voltage and frequency synchronization, that utilizes neighbor's DG information. The control law comprises of two terms, first term forces the agents to move towards following the reference value, whereas the second term causes the consensus among agents. The communication link delay analysis and upper bound on the allowable delay is derived in terms of the communication graph connectivity. From the obtained results, it is observed that this control scheme provides good tracking performance. However, the scheme does not guarantee finite-time restoration.
To deal with the sensitive loads and fast-changing operating conditions, and to obtain finite-time convergence, a distributed control scheme is then developed using the concept of cooperative control. A Lyapunov based stability and convergence analysis are presented which clearly shows that the convergence time is independent of microgrid system states and the microgrid line and load parameters. Flexible tuning of the convergence time is achieved by setting the controller parameters only. Also, for proportional power sharing, separate controllers have been designed in slower time-scale. From the results obtained, it is found that this controller has finite restoration time and also supports plug and play demand.
Another finite-time distributed control scheme is proposed which utilizes the information discovery scheme before the restoration operation, because of the unavailability of the global reference information with every distributed generator unit in a microgrid network. Further, this scheme provides finite-time frequency regulation and accurate reactive power-sharing along with the voltage restoration. The obtained results show that the proposed control scheme enables the plug and play operation and exhibits efficient performance under time-varying communication topology.
Further, a finite-time distributed control approach with constrained control input is proposed for voltage, frequency, and active power regulation. This control scheme also minimizes the control input transients and keep them well within their threshold limits.
To eliminate the effect of noise uncertainty and corrupted information reception, a noise-resilient control strategy is developed for voltage, frequency restoration. The proposed control scheme exhibit robust performance with changing communication topology, and changing noise parameters. It also outperforms than the existing noise resilient scheme in terms of restoration time and transients.
In order to demonstrate the effectiveness of the proposed control schemes, several simulation case studies of microgrid test system connected via a sparse communication
network are pursued in MATLAB/SimPowerSystem environment. The results are presented in the thesis together with the analysis
Development of Multi-Criteria Decision-making Model using Fuzzy-AHP Technique for Selection of Underground Metal Mining Method
No full textUnderground mining method selection is one of the most crucial decision-making tasks for the mining engineers or mine planners at the planning stage. The selection of mining method depends on multiple factors, including the geometry of ore body, geo-mechanical conditions of the ore body and adjacent strata, and available technology. Underground mining method selection is multi-criteria decision-making (MCDM) problem, and thus, the mine planners face the challenges in the selection of the appropriate mining method for a typical ore deposit. The selection of appropriate mining method for ore body extractions of a typical deposit is very important in order to maintain the profitability, safety, and productivity.
The proposed study aims to achieve the four objectives viz. development of a Fuzzy-Analytical Hierarchy Process (Fuzzy-AHP) based MCDM model for selection of optimum underground metal mining method, sensitivity analysis of the Fuzzy-AHP model for examining the robustness, comparative study of the results of the Fuzzy-AHP model with the other MCDM models (TOPSIS, VIKOR, improved ELECTRE, PROMETHEE II, and WPM), and development of a Graphical User Interface (GUI)-based software based on the developed algorithm.
The first step of the Fuzzy-AHP model development is to define the influencing factors or criteria of underground metal mining method. An individual factor may be either intrinsic or extrinsic in nature. The present study considered 11-criteria as intrinsic factors (dip, shape, thickness, depth, grade distribution, RMR of ore, RMR of hanging wall, RMR of foot wall, RSS of ore, RSS of hanging wall, and RSS of foot wall) and 5-criteria as extrinsic factors (productivity, recovery, dilution, flexibility, and safety). These criteria were further classified into 56 sub-criteria for evaluating the seven alternatives or mining method (block-caving (BC), sublevel stoping (SS), sublevel caving (SC), room and pillar mining (RP), shrinkage stoping (SH), cut and fill stoping (CF), and square set stoping (SQ)). The proposed Fuzzy-AHP model was formulated ina 4-layer hierarchical structure. The first layer of the hierarchy defined the nature of variables viz. intrinsic and extrinsic factors. The second layer listed different criteria under intrinsic and extrinsic factors. The third layer shows the sub-criteria for each criterion (listed in the second layer). The last layer defines alternatives or underground metal mining methods. In the next step, the local weights of each factor/criteria/sub-criteria/alternatives (listed in the different layer of the hierarchy) were determined using Fuzzy-AHP technique. The local weights were further used in determining the global weights of each mining method. The alternative/mining method received the highest weight or score for a particular ore deposit characteristic has been given first priority or first rank. In the same way, the mining method, which received the second highest weight has been given second priority or second rank and so on. The developed model was validated using two Uranium ore deposit (UCIL Tummalapalle deposit and UCIL Turamdih deposit) located in India. It was observed that the most suitable mining method for the UCIL Tummalapalle deposit was room and pillar and that of UCIL Turamdih deposit was cut and fill stoping as per the proposed MCDM model. To mine the respective ore deposits, similar mining methods (as that of the respective model output) were adopted in both the cases.
The next objective of the study is to conduct the sensitivity analysis of the Fuzzy-AHP model. The sensitivity analysis of the proposed Fuzzy-AHP model was conducted by varying the fuzzification factor (α) and decision-making attitude (λ) of the mine planners. The model output was analysed for six fuzzification factors (α= 0, 0.2, 0.4, 0.6, 0.8 and 1) in the range of 0 to 1 and three decision-making attitudes (λ= 0, 0.5, 1) in the range of 0 to 1. The fuzzification factor, α equal to 0, indicates no uncertainty in the observed variable, whereas α equal to 1 indicates maximum uncertainty. The three values of λ indicates pessimistic (λ = 0), unbiased (λ = 0.5), and optimistic (λ =1) decision-making attitude. The decision-making model output was analysed for each combination of α and λ. The sensitivity of the ranking of seven mining methods was analysed by considering the fuzzification factor in 2-factor, 16-criteria, 56-sub-criteria, and 7-mining method. The results indicated that the ranking or priorities of seven mining methods were not altered by either changing in the fuzzification factor or changing in the decision-making attitude. Therefore, for any combination of λ and α, the rank of a particular mining method remains the same. This indicates the robustness of the model under uncertainty in the variables.
The third objective of the proposed study is to make a comparative study of the results of Fuzzy-AHP model with the other MCDM models like TOPSIS, VIKOR, improved ELECTRE, PROMETHEE II, and WPM. The comparative results of six MCDM models (Fuzzy-AHP, TOPSIS, ELECTRE, PROMETHEE II, VIKOR, and WPM) were determined for two Uranium ore deposits (Tummalapalle and Turamdih) for analysis. The results revealed that five MCDM models (Fuzzy-AHP, TOPSIS, ELECTRE, PROMETHEE II, and WPM) give room and pillar mining method as a first priority mining method for Tummalapalle ore deposit, whereas, VIKOR model gives equal preference to two mining methods (room and pillar and sublevel stoping). Similarly, the most suitable mining method obtained for Turamdih ore deposit is cut and fill by four MCDM models (Fuzzy-AHP, TOPSIS, ELECTRE, and WPM), whereas, VIKOR model gives equal priority to cut and fill and sublevel stoping methods. PROMETHEE II model results assigned sublevel stoping as rank one and cut and fill method as second best mining method for the specified deposit. The comparative study results of six MCDM models indicate that all the models provided the same mining method as the first priority for both the ore deposit except in one case (PROMETHEE II for Turamdih deposit). Furthermore, the Fuzzy-AHP model outputs were matched with the adopted mining method for both the deposits. The additional advantage of Fuzzy-AHP model is its robustness and consideration of the uncertainty and decision-making attitude in the model.
The final objective is to develop a GUI-based software using the developed algorithms for the selection of underground metal mining method. The software also has the option of making the sensitivity analysis of Fuzzy-AHP model. The software tool can be easily implemented for the selection of underground metal mining method for a typical ore deposit without an in-depth analysis of the model by the user
Grid Synchronization Control Schemes for a Three Phase Grid connected Photovoltaic System with Power Quality Disturbances
No full textSynchronizing PV system with grid encounters a number of control challenges for maintaining the grid codes. These include various power quality problems such as voltage and current harmonics, voltage sag and swell, and grid frequency fluctuation. In this thesis it is intended to design suitable grid synchronization control scheme for a three-phase single stage grid connected PV system (TPSSGCPVS) considering power quality disturbances. The proposed control schemes are implemented both by simulation in MATLAB/Simulink followed by experimentation on a prototype TPSSGCPVS developed in the laboratory.
Firstly, the thesis focuses on the design of a Self-Tuning Filter-Proportional Integral (STF-PI) grid synchronization control scheme for TPSSGCPVS. The Self-Tuning Filter (STF) extracts the fundamental voltage of the distorted Point of Common Coupling (PCC) voltage and load current without any change in phase and amplitude of the fundamental component. To verify the effectiveness of the proposed STF-PI control scheme, a comparative analysis on its performance with that of the Improved Linear Sinusoidal Tracer-PI (ILST-PI) control scheme is pursued. Form the stability analysis, it is observed that the STF-PI control scheme has a wider range of stability region as compared to the ILST-PI control scheme. Simulations are performed by implementing these control schemes on a PV system considering the power quality disturbances. Subsequently, the proposed STF-PI control scheme is implemented in real-time on a prototype TPSSGCPVS developed in the laboratory. From both the simulation and experimental results obtained, it is verified that the proposed STF-PI control scheme provides effective grid synchronization of the PV system. Along with maximum PV power injection into the grid, the proposed STF-PI control scheme provides efficient harmonics compensation under PCC voltage distortion, load current distortion, load fault, PCC voltage sag and swell. From the obtained results, it is observed that using STF-PI control scheme, the grid current is maintained sinusoidal by reducing the harmonics as compared to ILST-PI control scheme. The current is injected into the grid at Unit Power Factor (UPF) by reducing the reactive current component to almost zero. The grid currents are maintained balanced and sinusoidal with reduced distortion despite load fault. The THD of the grid current is reduced from 26.7% to 4 % using the above STF-PI control scheme, satisfying the limits prescribed by the IEEE 519 grid code. The THD of the grid current is reduced to 4 % using STF-PI control scheme even under PCC voltage sag and swell conditions.
It is observed that, with a fixed cut-off frequency of STF, the THD of the grid current varies in real time as grid frequency varies. In order to further reduce the THD and reduce the THD variation, Extended Kalman Filtering (EKF) and Iterated EKF (IEKF) algorithms are employed for grid synchronization of a PV system. EKF and IEKF are used to estimate the fundamental sinusoidal component of the PCC voltage. IEKF uses an iterative loop to reduce the mean square error and increases the convergence speed of the grid current. From the simulation results it is observed that the grid current reaches the steady state faster using IEKF-PI control scheme than using EKF-PI and STF-PI control schemes. The THD of the grid current in real-time is reduced to the lowest value of 3.5% using the proposed IEKF-PI control scheme than the corresponding values of 3.6% and 4% respectively yielded in case of EKF-PI and STF-PI control schemes. Even by changing the grid frequency, the grid current is maintained sinusoidal using IEKF-PI control scheme. THD variation is minimized using IEKF and EKF-PI control schemes than STF-PI control scheme.
As IEKF uses the Jacobin matrix for linearization, the estimation accuracy is limited to first order approximation of the Taylor series. Unscented transformation is a nonlinear transformation, which propagates the mean and covariance through a nonlinear function. A set of sigma points is chosen to preserve the nonlinear nature of the system. Firstly, an Unscented Kalman (UKF) is proposed to further reduce the THD of the grid current and reduce the THD variation. In UKF, the sigma points are determined by finding the square root of the error covariance, obtained using Cholesky decomposition. In order to apply Cholesky decomposition, the error covariance matrix must be positive semi definite. The loss of the positive definiteness may result in stopping the UKF to run continuously or even cause divergence. To resolve the difficulties encountered in UKF, a Square Root Cubature Kalman Filter (SRCKF)-PI grid synchronization control scheme is proposed. From the obtained results, it is observed that the variation in THD of the grid current is minimized by both UKF-PI and SRCKF-PI control schemes as compared to IEKF-PI control scheme. The THD of the grid current is reduced to a lowest value to 3.2 % using SRCKF-PI control scheme than the corresponding values of 3.3% yielded by UKF-PI control scheme.
Form the obtained results with all the proposed control schemes for grid synchronization of the PV system, it is observed that these are able to maintain the grid codes by reducing the THD below 5%. However, the SRCKF algorithm essentially transmits the square root factors of the predictive and posterior error covariance in order to eliminate the square root operation thus providing the best convergence speed which minimizes the settling time. The estimation of the fundamental component of the PCC voltage using the cubature points in SRCKF algorithm provides increased estimation accuracy. As a result, the THD of the grid current is thus minimized to a value of 3.2 % using SRCKF-PI control scheme. It is thus concluded that amongst all the proposed controllers, SRCKF-PI control scheme exhibits the superior grid synchronization control performance with power quality disturbances
Modelling of Overbank Flow in Two-stage Meandering Channels
Get PDFThis research examines the flow in meandering compound channels through numerical and physical modelling which are significant for understanding the non-uniform flow and its behaviour. Accounting the momentum exchange at the junctions of a compound channel is a complex task in order to develop an improved model for predicting stage-discharge relationship, distribution of the flow in subsections, resistance, and distribution of boundary shear force.
In literature, much of experimental research works are focussed on simple meandering channels and less for meandering compound channel, while almost nil works has been carried out for doubly meandering compound channel (where both main channel and floodplain levees are meander). Experiments have been conducted on two stage meandering channels with different sinuosity constructed at the hydraulics-engineering laboratory of the department of civil engineering, National Institute of Technology Rourkela (NITR), India. The effectiveness of Manning’s n is analysed for the different flow configurations of meandering compound channels. A model is developed for determining Manning’s roughness coefficient which depends on the non-dimensional parameters like width ratio, relative flow depth, sinuosity ratio, meander belt width ratio, and bed slope. Various data driven models such as multivariate adaptive regression spline (MARS), group method of data handling (GMDH), gene-expression programming (GEP) and support vector regression approaches have been used to develop a model for predicting the Manning’s roughness coefficient of meandering compound channels by taking care of the aforementioned geometric and hydraulic parameters. These developed model equations through MARS, GMDH, GEP, and SVR approaches can be useful as a practical tool for the prediction of Manning’s roughness coefficient in a natural channel.
Moreover, the model is further used for estimating conveyance for large-scale as well as small-scale channels. Results of the developed model is compared with established approaches for calculating roughness coefficient which leads to the assessment of conveyance capacity of the meandering compound channels. The performance of all the developed models are evaluated by means of various statistical measures and uncertainty analysis to determine the best alternate. The models are developed using relevant experimental data obtained from laboratory experiments and the data from other researchers on the meandering compound channels. The results are found to be in agreement with experimental as well as river discharge data.
The flow structure in a compound channels becomes complicated due to the transfer of momentum between the deep main channel and the adjoining floodplains; which affects the shear stress distribution across the perimeter. Accurate prediction of shear stress distribution along the boundary in an open channel is the key to the solution of numerous critical engineering problems such as flood control, sediment transport, river bank protection and others. Therefore, an investigation concerning the distribution of bed shear stress in the main channel and the floodplains of meandering compound channels are presented. Models for predicting the percentage sharing of shear force for floodplain are developed using multivariate adaptive regression spline (MARS), group method of data handling (GMDH) and gene-expression programming (GEP) by taking five dimensionless parameters as the inputs. The width ratio, relative depth, sinuosity, bed slope, and meander belt width ratio of the channel are taken as input parameters. Influence of each parameter on predicting the percentage of shear force at floodplain by the developed models is also analyzed by adopting a sensitivity analysis. The predictive results are compared with results based on in situ measurement using other data driven approaches like support vector regression (SVR), and K-nearest neighbors (KNN). A comparative analysis of the developed MARS, GMDH and GEP model and previously developed analytical models are presented. (% ) fp S
The conventional channel division methods assume zero apparent shear forces on the respective vertical, diagonal, horizontal and variable-inclined interfaces. A modified variable inclined interface (MVI) is proposed by using GEP for which apparent shear force is calculated as zero. Modified variable inclined interfaces are also used to calculate discharge in meandering compound channels. Performance of the developed models of shear force percentage is evaluated with previously developed analytical methods through different statistical measures. Using the modified-inclined interface, the error between the measured and calculated discharges for the meandering compound channel is found to be the minimum when compared with that using other interfaces. Moreover, the equations agree well for predicting discharge for large-scale as well as small-scale channels besides the natural river data.
In this research work, an attempt is made to improve a discharge estimation method where the modified variable inclined interface divides the main channel as well as outer and inner
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