Amrit verma - Academia.edu (original) (raw)

Papers by Amrit verma

Research paper thumbnail of A review of impact loads on composite wind turbine blades: Impact threats and classification

Renewable and Sustainable Energy Reviews

Research paper thumbnail of A transparent machine learning algorithm to manage diabetes: TDMSML

Advances in Computational Intelligence

Diabetes is nowadays a very common medical problem among the people worldwide. The disease is bec... more Diabetes is nowadays a very common medical problem among the people worldwide. The disease is becoming more prevalent with the modern and hectic lifestyle followed by people. As a result, designing an adequate medical expert system to assist physicians in treating the disease on time is critical. Expert systems are required to identify the major cause(s) of the disease, so that precautionary measures can be taken ahead of time. Several medical expert systems have already been proposed, but each has its own set of shortcomings, such as the use of trial and error methods, trivial decision-making procedures, and so on. As a result, this paper proposes a Transparent Diabetes Management System Using Machine Learning (TDMSML) expert system that uses decision tree rules to identify the major factor(s) of diabetes. The TDMSML model comprises of three phases: rule generation, transparent rule selection, and major factor identification. The rule generation phase generates rules using decision tree. Transparent rule selection stage selects the transparent rules followed by pruning the redundant rules to get the minimized rule-set. The major factor identification stage extracts the major factor(s) with range(s) from the minimized rule-set. These factor(s) with certain range(s) are characterized as major cause(s) of diabetes disease. The model is validated with the Pima Indian diabetes data set collected from Kaggle. Keywords Data mining • Decision tree • Rule pruning • Expert system • Diabetes management 1 Introduction Diabetes Mellitus (DM), also known as Diabetes, is a chronic disease characterized by elevated blood glucose levels (hyperglycemia). Diabetes Mellitus is classified into two types: Type 1 Diabetes Mellitus (T1DM) and Type 2 Diabetes Mellitus (T2DM) (T2DM). T1DM raises blood glucose B Manomita Chakraborty

Research paper thumbnail of Nonlinear Hydrostatic Restoring Characteristics of a Spar Floating Wind Turbine

Volume 5A: Ocean Engineering

Floating wind turbine technologies have worldwide applications. Regarding the wind turbine floate... more Floating wind turbine technologies have worldwide applications. Regarding the wind turbine floater stability, there are three principal design philosophies: ballast-, buoyancy- and mooring-stabilized. Although linear hydrostatic stiffness coefficient has been applied in most hydro-aero-elastic codes, accurate calculation of the nonlinear hydrostatic restoring forces is important for the floating stability evaluation and load. This study selects a 5-megawatt spar floating wind turbine as a representative floater. The nonlinear hydrostatic stiffness coefficient for different heeling angles is analytically calculated and compared against those obtained by a hydrodynamic software, and an excellent match is shown. A sensitivity study is carried out to consider the uncertainties in the hydrostatic stiffness due to varying geometry and weight distribution. The present results can be applied in the time-domain simulations for floating wind turbines.

Research paper thumbnail of Minimum Leading Edge Protection Application Length to Combat Rain-Induced Erosion of Wind Turbine Blades

Energies

Leading edge erosion (LEE) repairs of wind turbine blades (WTBs) involve infield application of l... more Leading edge erosion (LEE) repairs of wind turbine blades (WTBs) involve infield application of leading edge protection (LEP) solutions. The industry is currently aiming to use factory based LEP coatings that can applied to the WTBs before they are shipped out for installation. However, one of the main challenges related to these solutions is the choice of a minimum LEP application length to be applied in the spanwise direction of the WTBs. Generally, coating suppliers apply 10–20 m of LEP onto the blades starting from the tip of the blade using the “rule of thumb”, and no studies in the literature exist that stipulate how these LEP lengths can be calculated. In this study, we extend the scope of a recently developed long-term probabilistic framework to determine the minimum LEP application length required for WTBs to combat rain-induced erosion. A parametric study is performed where different wind turbines with varying power ratings of 2.1 MW to 15 MW at different Dutch sites rangi...

Research paper thumbnail of Impact assessment of a wind turbine blade root during an offshore mating process

Engineering Structures, 2019

Single-blade installation is a popular method for installing blades on bottom-fixed offshore wind... more Single-blade installation is a popular method for installing blades on bottom-fixed offshore wind turbines. A jackup crane vessel is often employed, and individual blades with their roots equipped with mechanical joints and bolted connections are lifted to the tower-top height and mated with a pre-assembled hub. The final mating phase is challenging and faces significant risks of impact. Due to relative motions between the blade and the hub, substantial impact forces may arise and lead to severe structural damages at root connections, thereby causing delays in the installation task. The present paper considers a realistic scenario of the mating process and investigates the consequences of such impact loads. Here, a single-blade model with tugger lines and a monopile model were established using a multi-body formulation, and relative velocities under collinear wave and wind conditions were obtained. A three-dimensional finite element model was developed for the blade root with Tbolt connections, and an impact investigation was performed for the case in which a guiding connection impacts the hub. The results show severe bending and plastic deformation of the guide pin bolt together with failure of the adjoining composite laminate at the root connection. Based on the type of damage obtained for the different environmental conditions considered, this paper also discusses its consequence on the installation tasks and suggests onboard decision making in case of an impact incident. The results of this study provide new insights regarding the mating phase and can be utilised to establish response-based operational limits.

Research paper thumbnail of A Global-Local Damage Assessment Methodology for Impact Damage on Offshore Wind Turbine Blades During Lifting Operations

Volume 10: Ocean Renewable Energy, 2018

Structural analysis of floating wind turbines is normally carried out with the hull considered as... more Structural analysis of floating wind turbines is normally carried out with the hull considered as a rigid body. This paper explores the consequences of modeling the pontoons of a tension leg platform (TLP) wind turbine as flexible structures. The analysis is based on numerical simulations of free decays, structural response to wave excitation and short-term fatigue damage accumulation at chosen points of the platform. In addition, the importance of considering hydroelasticity effects is evaluated. It is observed that pontoon flexibility can change the platform natural periods significantly, as well as the intensity and peak frequencies of internal structural loads. The adoption of a fully rigid-body is shown to be non-conservative for the fatigue damage analysis. Loads due to hydroelasticity have order of magnitude comparable to those related to rigid-body motions, but still lower enough to be considered of secondary importance.

Research paper thumbnail of A review of impact loads on composite wind turbine blades: Impact threats and classification

Renewable and Sustainable Energy Reviews

Research paper thumbnail of A transparent machine learning algorithm to manage diabetes: TDMSML

Advances in Computational Intelligence

Diabetes is nowadays a very common medical problem among the people worldwide. The disease is bec... more Diabetes is nowadays a very common medical problem among the people worldwide. The disease is becoming more prevalent with the modern and hectic lifestyle followed by people. As a result, designing an adequate medical expert system to assist physicians in treating the disease on time is critical. Expert systems are required to identify the major cause(s) of the disease, so that precautionary measures can be taken ahead of time. Several medical expert systems have already been proposed, but each has its own set of shortcomings, such as the use of trial and error methods, trivial decision-making procedures, and so on. As a result, this paper proposes a Transparent Diabetes Management System Using Machine Learning (TDMSML) expert system that uses decision tree rules to identify the major factor(s) of diabetes. The TDMSML model comprises of three phases: rule generation, transparent rule selection, and major factor identification. The rule generation phase generates rules using decision tree. Transparent rule selection stage selects the transparent rules followed by pruning the redundant rules to get the minimized rule-set. The major factor identification stage extracts the major factor(s) with range(s) from the minimized rule-set. These factor(s) with certain range(s) are characterized as major cause(s) of diabetes disease. The model is validated with the Pima Indian diabetes data set collected from Kaggle. Keywords Data mining • Decision tree • Rule pruning • Expert system • Diabetes management 1 Introduction Diabetes Mellitus (DM), also known as Diabetes, is a chronic disease characterized by elevated blood glucose levels (hyperglycemia). Diabetes Mellitus is classified into two types: Type 1 Diabetes Mellitus (T1DM) and Type 2 Diabetes Mellitus (T2DM) (T2DM). T1DM raises blood glucose B Manomita Chakraborty

Research paper thumbnail of Nonlinear Hydrostatic Restoring Characteristics of a Spar Floating Wind Turbine

Volume 5A: Ocean Engineering

Floating wind turbine technologies have worldwide applications. Regarding the wind turbine floate... more Floating wind turbine technologies have worldwide applications. Regarding the wind turbine floater stability, there are three principal design philosophies: ballast-, buoyancy- and mooring-stabilized. Although linear hydrostatic stiffness coefficient has been applied in most hydro-aero-elastic codes, accurate calculation of the nonlinear hydrostatic restoring forces is important for the floating stability evaluation and load. This study selects a 5-megawatt spar floating wind turbine as a representative floater. The nonlinear hydrostatic stiffness coefficient for different heeling angles is analytically calculated and compared against those obtained by a hydrodynamic software, and an excellent match is shown. A sensitivity study is carried out to consider the uncertainties in the hydrostatic stiffness due to varying geometry and weight distribution. The present results can be applied in the time-domain simulations for floating wind turbines.

Research paper thumbnail of Minimum Leading Edge Protection Application Length to Combat Rain-Induced Erosion of Wind Turbine Blades

Energies

Leading edge erosion (LEE) repairs of wind turbine blades (WTBs) involve infield application of l... more Leading edge erosion (LEE) repairs of wind turbine blades (WTBs) involve infield application of leading edge protection (LEP) solutions. The industry is currently aiming to use factory based LEP coatings that can applied to the WTBs before they are shipped out for installation. However, one of the main challenges related to these solutions is the choice of a minimum LEP application length to be applied in the spanwise direction of the WTBs. Generally, coating suppliers apply 10–20 m of LEP onto the blades starting from the tip of the blade using the “rule of thumb”, and no studies in the literature exist that stipulate how these LEP lengths can be calculated. In this study, we extend the scope of a recently developed long-term probabilistic framework to determine the minimum LEP application length required for WTBs to combat rain-induced erosion. A parametric study is performed where different wind turbines with varying power ratings of 2.1 MW to 15 MW at different Dutch sites rangi...

Research paper thumbnail of Impact assessment of a wind turbine blade root during an offshore mating process

Engineering Structures, 2019

Single-blade installation is a popular method for installing blades on bottom-fixed offshore wind... more Single-blade installation is a popular method for installing blades on bottom-fixed offshore wind turbines. A jackup crane vessel is often employed, and individual blades with their roots equipped with mechanical joints and bolted connections are lifted to the tower-top height and mated with a pre-assembled hub. The final mating phase is challenging and faces significant risks of impact. Due to relative motions between the blade and the hub, substantial impact forces may arise and lead to severe structural damages at root connections, thereby causing delays in the installation task. The present paper considers a realistic scenario of the mating process and investigates the consequences of such impact loads. Here, a single-blade model with tugger lines and a monopile model were established using a multi-body formulation, and relative velocities under collinear wave and wind conditions were obtained. A three-dimensional finite element model was developed for the blade root with Tbolt connections, and an impact investigation was performed for the case in which a guiding connection impacts the hub. The results show severe bending and plastic deformation of the guide pin bolt together with failure of the adjoining composite laminate at the root connection. Based on the type of damage obtained for the different environmental conditions considered, this paper also discusses its consequence on the installation tasks and suggests onboard decision making in case of an impact incident. The results of this study provide new insights regarding the mating phase and can be utilised to establish response-based operational limits.

Research paper thumbnail of A Global-Local Damage Assessment Methodology for Impact Damage on Offshore Wind Turbine Blades During Lifting Operations

Volume 10: Ocean Renewable Energy, 2018

Structural analysis of floating wind turbines is normally carried out with the hull considered as... more Structural analysis of floating wind turbines is normally carried out with the hull considered as a rigid body. This paper explores the consequences of modeling the pontoons of a tension leg platform (TLP) wind turbine as flexible structures. The analysis is based on numerical simulations of free decays, structural response to wave excitation and short-term fatigue damage accumulation at chosen points of the platform. In addition, the importance of considering hydroelasticity effects is evaluated. It is observed that pontoon flexibility can change the platform natural periods significantly, as well as the intensity and peak frequencies of internal structural loads. The adoption of a fully rigid-body is shown to be non-conservative for the fatigue damage analysis. Loads due to hydroelasticity have order of magnitude comparable to those related to rigid-body motions, but still lower enough to be considered of secondary importance.