1. Ph.D Theses
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Item Hydraulic Modelling Of Unsteady Flow And Flood Routing In Nethravathi River Basin, India(National Institute of Technology Karnataka, Surathkal, 2022) . Pramodkumar; M. K., NAGARAJ; Chandra Deka, PareshRiver systems need improved hydraulic models in order to better simulate river conditions at different points in time. Flooding is one of the changes in the flow characteristics of a river. Also, Channel roughness co-efficient is found to be a critical factor that is dynamic in nature influencing the flow characteristics of a river. The variation of roughness co-efficient based on the riverbed material and morphology affects the fluvial erosion and deposition altering the channel geometry. However, the parameter has been consistently considered as a constant value for the simulation in the numerical models. On the contrary, various experimental studies and analytical models have revealed roughness co-efficient to be one of the sensitive parameter in simulation of flow. Various models were developed for study to analyze the influences of the bed morphology (Roughness coefficient, the shape of the channel, channel slope) on discharge and water level at various locations of the river. It is also proved to be good means to assess the impacts for its capability to do the sensitivity analysis and to predict flood flow and inundated area. The aim of the present study is to simulate unsteady flow analysis using hydraulic model HEC-RAS for Nethravathi River basin in India for identifying the impact of variability in roughness co-efficient on the river-stage and discharge. Also, it is intended to assess the hydraulic response of the river using flood-routing analysis and to study sensitivity of geometric and computational parameters on model results and stability. A river length of 45 km of the Nethravathi river regime, Karnataka from Uppinangadi and Kumaradhara to Bantwal is considered for the study. HEC-RAS model was used for the simulation of surface water levels and discharge values. Manning’s roughness coefficient and river cross sections were defined for the calibration of observed river stage and discharge data. The model is built to examine the hydraulic response in Nethravathi River basin for a calibration period of 2007 - 2009 and validation period of 2010. The simulated model results provided good correlation between observed and simulated discharge and stage respectively. The error function values during validation are found to be marginally lower in ii comparison to calibration results. Thus, considering the overall values of the error functions for the gauging station, it is found that the model performs reasonably well for unsteady flow analysis. The variation of Manning’s roughness coefficient was observed to affect the river stage and thereby influencing the associated peak discharges. The coefficients of correlation for the developed rating curves showed the best fit for Manning’s n=0.070 flood plain. The peak discharge computation accuracy is approximately 80% in the calibration period and 88% in the validation period. The maximum water level computation accuracy is approximately 93.33% in the calibration period and 97.23% in the validation period. Depth of the flood is found to range between 0.1 m to 14.98 m. Velocity of flow along the whole river reach is found to vary between 0.01 m/s to 7.43 m/s. The maximum depth of flow in channel and floodplain is 7.75 m and 3.37 m respectively at downstream gauging station. However, the maximum velocity in the downstream of the river channel is found vary between 0.28 m/s to 1.71 m/s consequently, the river stage and discharge along the cross-section of flow were disturbed resulting in the flooding of river banks and inundation of low lying areas. Flood inundation map shows the spatial variation of the flood in the floodplains of the Nethravathi basin. Flood water flows over the riverbank in the upstream of the Uppinangadi gauging station, near the Nethravathi-Kumaradhara river confluence and at the meandering section in upstream of the Bantwal gauging station. The Manning’s roughness coefficient, normal depth, time step and θ-weighting parameter were considered to test the model sensitivity. The results from the sensitivity analysis showed that the model is very sensitive to the choice of Manning’s n. Reducing Manning’s n will decrease magnitude of peak and stage, and reduce the total inundation extent. The output is more sensitive to Manning’s n than time step, θ- parameter, cross-section spacing and normal depth. This indicates that the choice of friction coefficient can to some extent overshadow the uncertainties related to insufficient geometry data and the numerical solution.Item Analysis of Shoulder and Knee Joint Muscles using Developed CPM Machine and Finite Element Method(National Institute of Technology Karnataka, Surathkal, 2016) Sidramappa, Metan Shriniwas; Mohankumar, G. C.; Krishna, PrasadShoulder and knee joints pain, injury and discomfort are public health and economic issues world-wide. As per the Indian orthopedic association survey, there are about 50% of the patient visits to doctors' offices because of common shoulder and knee injuries such as fractures, dislocations, sprains, and ligament tears. Shoulder and knee are the most complex, maximum used and critical joints in the human body. The shoulder and knee joint muscle behaviour during different exercises is one of the major concerns to the orthopedic surgeon for analysing the exact healing and duration of the injury. Quantification of mechanical stresses and strains in the human joints and the musco-skeletal system is still a big concern for the researchers. The injury mechanisms and analysis of the post-operative progress is one of the most critical studies for orthopedic surgeons, biomechanical engineers and researchers. In the present work a classical 3D Finite Element Method (FEM) modelling technique has been used to investigate the stresses induced in the shoulder joint muscles during abduction arm movement and knee joint muscles during flexion leg movement for different range of motion. 3D model provides valuable information for analysing complex bio-mechanical systems and characterization of the joint mechanics. Reverse modelling method was used for generating fast, accurate and detailed contours of the shoulder and knee model. Scanning of the complicated shoulder and knee joint bones were made by 3D scanner (ATOS III) to generate ‘.stl’ file. Accurate and detailed 3D bone geometry of the shoulder and knee joint models was done using CATIA V5 software from the scanned ‘.stl’ file. The higher order geometrical features (curve and surfaces) were designed by filtering and aligning number of cloud points, tessellation of polygonal model, recognition and defining the referential geometrical entities. According to quadratic dependency, a non-homogeneous bone constitutive law was implemented. Different muscles were then added on the shoulder and knee joint models in CATIA V5. 3D models were then imported in ‘.igs’ format into ANSYS workbench for the stress analysis. A 3D FEM model was developed for the five important shoulder joint muscles, namely deltoid, supraspinatus, subscapularies, teres minor and infraspinatus. Thekinematics for shoulder abduction arm movement was prescribed as an input to finite element simulations and the Von Mises stresses and equivalent elastic strain in the shoulder muscles were plotted. Individual and group muscle analysis was done to evaluate the Von Mises stresses and equivalent elastic strain of the shoulder muscles during the abduction arm movement. During the individual muscle analysis, the Von Mises stresses induced in deltoid muscle was maximum (4.2175 MPa) and in group muscle analysis it was (2.4127MPa) compared to other individual four rotor cuff muscles. During the individual muscle analysis, the equivalent elastic strain induced in deltoid muscle was maximum (3.5146 mm/mm) and in group muscle analysis it was (2.0106 mm/mm) compared to other individual four rotor cuff muscles. The percentage analysis of individual muscles contribution for abduction arm movement predicted by FEM analysis was maximum (46.85%) in the deltoid muscle. The results showed that deltoid muscle was the most stressed muscle in both individual and group muscle analysis. The Surface Electromyography (SEMG) test was conducted on the shoulder prone subjects using the developed low cost shoulder Continuous Passive Motion (CPM) machine. The percentage analysis of individual muscles contribution for abduction arm movement predicted by SEMG analysis was maximum (48.15%; 46.15% and 47.05%) in the deltoid muscle. Deltoid was the most contracted (stressed) muscle observed during the SEMG analysis amongst the five shoulder muscles. The results showed by both FEM and SEMG methods that deltoid muscle was the most sensitive amongst the five shoulder joint muscles during abduction arm movement. FEM analysis was done to investigate the Von Mises stresses in two important knee joint muscles such as the rectus femoris and biceps femoris muscle during the flexion leg movement. During the muscle analysis, the Von Mises stresses induced in rectus femoris muscle was the maximum (1.5579 MPa). The results showed that rectus femoris muscle was the most stressed muscle than the biceps femoris muscle during flexion leg movement. The SEMG test was conducted on the knee prone subjects using the developed low cost knee CPM machine. The average percentage contraction (stress distribution) exhibited by SEMG analysis on the rectus femoris muscle was 70% of the totalmuscles contraction. The results by both FEM and SEMG methods showed that rectus femoris was the most stressed muscle during the flexion leg movement. The present work provides in depth information to the researchers and orthopedicians for the better understanding of the shoulder and knee joint mechanism in human anatomy. It predicts the most stressed muscle in the shoulder joint during the abduction arm movement and in the knee joint during the flexion leg movement at different range of motion.Item Sensitivity of Risks in Construction Scheduling(National Institute of Technology Karnataka, Surathkal, 2017) Colaco, Rohan Maxwel; Nagaraj, M. K.Construction industry is growing by leaps and bounds in recent times. The number of stakeholders and investments in the construction industry is increasing. With the growth in population there is a massive increase in demand for on time delivery of finished products. An overall wide spread public awareness and upsurge of rating agencies has increased the quality expectations of the customers. Due to challenges in construction, new processes are devised to improve efficiency and add value to the customer. Hence the construction projects are vulnerable to various technical and business risks that are significant in the execution of the project. The core of this research is based on recognizing the various risks in construction projects. Once the risks are recognized the attempt is to quantify the risks. Subjecting the risks to sensitivity analysis gives a better understanding when the accompanying costs are included. Sensitivity analysis of risks and costs helps to compare the various preferences that a constructor has by using present value analysis. The constructor is equipped to take a reasonable decision based on the data analysis available. This research seeks to identify and assess the risk and to develop a risk management framework which the investors, developers and contractors easily adopt. Risks vary due to differences in prevailing conditions that are specific to a particular region. It is decided to approach a particular geographical region for the research study. The general methodology of this study relies largely on the survey questionnaire that is collected from the experienced engineers of Mangalore region. In order to analyze the risks they need to be quantified. Broad based attempts to quantify risks do not give a fair idea. The study of risks is concentrated to a particular geographical region through a questionnaire survey. The survey questionnaire is designed to probe the cross-sectional behavioral pattern of risks in construction industry. The questionnaire prepared for the pilot survey is formulated by reviewing the relevant literature in the area of construction risk management. It is not possible to give a common risk matrix for construction projects in India. The geographical divide of India is a challenge due to prevailing risk factors. It is invariable to select smaller segments of geographical area for the purpose of study. These regions have similarity in conditions. A model developed in a particular region is easily replicable.Construction activities vary with type of projects. They are classified as private, public or private public partnership projects and so on. In the present study the construction projects in Mangalore city are taken as the pilot sample. The private residential projects that consist of apartments, houses and commercial complexes are considered as the group under study. The risks associated with the above construction activity are obtained through a questionnaire survey. The study is limited to the private construction projects of Mangalore region. The opinions are collected from experienced engineers among the stakeholders. The outcome of the survey is analyzed using various statistical formulae to obtain the risk in construction projects of Mangalore region. The weights given to the risk are an important measure to understand the importance and rank of the risks. The standard deviation of the responses signifies reliability of the data. The research proposes a risk management framework that uses the results of the survey to mitigate the risks in construction. It is done using sensitivity analysis of risk values and cost to obtain a risk cost that mitigates risk. It provides a comprehensive risk management system which is sensitive to the risks and cost of activities in project schedule. The use of time series for price forecasting and Present Value Analysis make the risk management system more credible.