Bhuneshwar Prasad

Erythropoietin levels in lowlanders and high-altitude natives at 3450 m.

BACKGROUND This study is aimed to determine whether short or prolonged residency at high altitude (HA) elicits erythropoietin (EPO) secretion effectively in subjects who were able to acclimatize and those who were not able to acclimatize and suffered from acute mountain sickness (AMS) and high altitude pulmonary edema (HAPE). METHODS Plasma EPO was measured in 16 lowland residents (LLR) at sea level (SL) and during 11 d of their sojourn at an altitude of 3450 m. Identical studies were also conducted in LLR acclimatized to HA (LLR-accl), high altitude natives (HAN) and in patients of AMS and HAPE. RESULTS In LLR at SL, the mean +/- SD EPO levels were 8.93 +/- 3.75 mU x ml(-1), increased significantly after 8 h (20.0 +/- 11.06) of arrival at HA, peaked by day 1 (27.91 +/- 10.74 mU x ml(-1)), and started declining thereafter. The hemoglobin and hematocrit also increased after 8 h of arrival at HA and the increased levels were maintained during sojourn at high altitude. The EPO levels in LLR-accl were found to be significantly higher than the LLR SL values, but were not significantly different in HAN. The EPO levels in patients of AMS were not significantly different than the LLR values during the initial 2 d after arrival at HA but were found to be increased in patients of HAPE. CONCLUSION Short or prolonged residency at HA is associated with increased secretion of EPO. The EPO response to hypoxia is not significantly altered in AMS but is markedly enhanced in HAPE, which may be due to exaggerated hypoxemia in these patients.

Bio-harmonized Dynamic Model of a Biology Inspired Carangiform Robotic Fish Underwater Vehicle

Abstract This paper presents a novel dynamic model of a bio-inspired robotic fish underwater vehicle by unifying conventional rigid body dynamics and bio-fluid-dynamics of a carangiform fish swimming given by Lighthills (LH) slender body theory It proposes an inclusive mathematical design for better control and energy efficient path travel for the robotic fish. The system is modeled as an 2-link robot manipulator (caudal tail) with a mobile base (head). Lighthill caudal-tail reactive forces and moments are shown to contribute towards thrust generation and yaw balance. These LH reactive forces are shown to generate the inertial added mass during the robotic fish locomotion. This forward thrust drives the robotic fish head represented by a unified non-linear equation of motion in earth fixed frame. Using the proposed dynamic model an open-loop (manual) operating region for the identified kinematic parameter tail beat frequency (TBF) is established. Obtained Kinematic results also resemble with real fish kinematic results. The objective is to mimic the propulsion technique of the carangiform swimming style and to show the fish behavior navigating efficiently over large distances at impressive speeds and its exceptional character in fluid environment.

Optimal placement of off-shore wind turbines and subsequent micro-siting using Intelligently Tuned Harmony Search algorithm

The placement of wind turbines in a wind farm is configured to minimize wake interactions between individual turbines to ensure maximum power generation. Unrestricted Wind Farm Layout Optimization (UWFLO) in conjunction with Intelligently Tuned Harmony Search (ITHS) was employed to optimize the placement of wind turbines, given constraints of farm boundary, number of turbines and wind conditions. UWFLO takes into account the overlap between the wake generated by an upstream turbine and the blades of a downstream turbine to predict the total power generated by a wind farm (with greater accuracy). The study was run for three cases: 1) Constant wind speed and constant wind direction; 2) Constant wind speed and variable wind direction and 3) Variable wind speed and variable wind direction. Comparisons were made with other optimization algorithms, viz Genetic Algorithm (GA), Harmony Search (HS) and Improved Harmony Search (IHS). ITHS was unable to perform better than GA in Case 1, but delivered better results by 4% in Case 2 and 6% in Case 3.

Kinematics study and implementation of a biomimetic robotic-fish underwater vehicle based on Lighthill slender body model

Sir J. Lighthill mathematical slender body swimming model formulates the biological fish propulsion mechanism (undulation) in fluid environment. The present research has focused on the relevance of Lighthill (LH) based biomimetic robotic propulsion. The objective of this paper is to mimic the propulsion mechanism of the BCF mode carangiform swimming style to show the fish behavior navigating efficiently over large distances at impressive speeds and its exceptional characteristics. The robotic fish model (kinematics and dynamics) is integrated with the Lighthill (LH) mathematical model framework. Comparative studies are undertaken between a LH model based and a non-LH based model. A comprehensive propulsion mechanism study of the different parameters namely the tail-beat frequency (TBF), the propulsive wavelength, and the caudal amplitude are studied under this framework. Yaw angle study for the underwater robotic fish vehicle is also carried out as it describes the course of the robotic fish vehicle. Inverse kinematics based approach is incorporated for trajectory generation of the robotic fish vehicle motion. Analysis of these critical parameters affecting the kinematics study of the vehicle vis a vis the real fish kinematic study [8] is carried out for a given trajectory. TBF is found to be the effective controlling parameter for the forward speed of the vehicle over a wide operating conditions. Performances and comparative results of propulsive wavelength and amplitude variations are also shown and discussed.

Smart-metering for monitoring building power distribution network using instantaneous phasor computations of electrical signals

This paper presents a smart-metering framework based on computations of instantaneous phasors of voltage and current signals measured at a given node. The idea and requirement of electrical transparency inside a building is presented initially. Then the implementation of phasor estimation algorithm is discussed for the purpose of smart-metering. The capability of the smart-meter to do detailed power quality analysis is also presented. The ongoing work of hardware implementation and real-time testing of such smart-metering is also mentioned in the paper.

Design, modeling and open-loop control of a BCF mode bio-mimetic robotic fish

This paper deals with the design of a bio-inspired fish like underwater vehicle. As the applications of underwater robots grow, finding efficient propulsion techniques is of the utmost importance. The current research has focused on the use of biomimetic propulsion, which simulates the undulation of fish tail, i.e. the sinusoidal oscillation. The objective is to mimic the propulsion technique of the BCF mode carangiform swimming style to swim efficiently over large distances at impressive speeds. Beginning from the CAD construction in Solidworks, 3D motion simulations in Matlab VRML and open-loop experimental and simulation results are provided to illustrate the effectiveness of the proposed methodology.

Inverse dynamics control of a bio-inspired robotic-fish underwater vehicle propulsion based on Lighthill slender body theory

A 2-joint, 3-link multibody vehicle model biologically inspired by a Body Caudal Fin (BCF) carangiform fish propulsion mechanism in fluid environment is presented in this paper. Under the Lighthill (LH) mathematical slender body theory different mathematical propulsive waveforms are developed to generate robotic fish locomotion. LH Cubic function is found to be 16.32 % efficient than a non-LH function. We develop the dynamic motion control strategy of the robotic fish based on two different control schemes, the CTM (Computed-Torque Method) and the FF (Feed-Forward) controller both with dynamic PD compensation. An inverse dynamic control method based on non-linear state function model including hydrodynamics is proposed to improve tracking performance. CTM control generates a feedback loop for linearization and decoupling robot dynamic model with a shorter response time while a dynamic PD compensation in the feed-forward path is employed by FF scheme through the desired trajectories. This model based strategy results in an improved tracking. Overall results indicate that control designs based on the inverse dynamic model are useful for robotic fish motion tracking.

Finding an operating region for a bio-inspired robotic fish underwater vehicle in the Lighthill framework

Sir J. Lighthill mathematical slender body swimming model formulates the biological fish propulsion mechanism (undulation) in fluid environment. The present research has focused on the relevance of Lighthill (LH) based biomimetic robotic propulsion. A 2-joint, 3-link multibody vehicle model biologically inspired by a Body Caudal Fin (BCF) carangiform fish propulsion mechanism is designed. Different mathematical propulsive waveforms are proposed in LH frame-work to generate posterior body undulation. These functions are combined with inverse kinematics to generate various bio-inspired trajectories for the robotic fish vehicle motion. The robotic fish model (kinematics and dynamics) is integrated with the Lighthill (LH) mathematical model framework. Comparative studies are undertaken among a LH model and the proposed propulsive wave models. LH Cubic and NURB quadratic functions are found to be 16.32 % and 17.94 % efficient than a non-LH function respectively. Based on the simulation results of critical kinematic parameters TBF and Propulsive wavelength, an operating region is established to facilitate the open-loop (manual) control experiments.

Genetic algorithm based intelligent station-keeping for spherical underwater robot

In this paper, a spherical underwater robot is proposed that uses six degree of freedom thrust allocator to determine the magnitude and the direction of thrust required for each water-jetted bilge pump thruster to create force and moment equilibrium. However, in order to ensure safe operation of the underwater robot it is equipped with redundant thruster configuration and therefore is over-actuated. Therefore, the choice of a particular solution for thrust allocation is found using an optimization process. In this work, the thrust allocation problem is formulated as an optimization problem, with an objective to minimize the total power consumption of the spherical underwater robot. A set of all physically realizable surge, sway and heave force for the ith thruster is called as its Attainable Thrust Region (ATR). Since the thrust force produced by each thruster is restricted to its ATR, the power consumption of underwater robot is determined by establishing a relationship between the power consumption and the thrust of an individual bilge pump. The formulated optimal thrust allocation problem is solved using Mincon (Sequential Quadratic Programming) and GA (Genetic Algorithm) optimization algorithm. The percentage savings in total power consumption for thruster system using the GA as compared to Mincon method is 33.82 %.

Energy-efficient optimal thrust allocation for spherical underwater robot

In this paper, a spherical underwater robot uses optimal thrust allocator to determine the magnitude and the direction of thrust required for each water-jetted bilge pump thruster to create force and moment equilibrium. However, in order to ensure safe operation of the underwater robot it is equipped with redundant thruster configuration and therefore is over-actuated. Therefore, the choice of a particular solution for thrust allocation is found using an optimization process. In this work, the thrust allocation problem is formulated as an optimization problem, with an objective to minimize the total power consumption of the spherical underwater robot. The power consumption of underwater robot depends on the thrust generated by each bilge pump. The relationship between the power consumption and the thrust of the bilge pump is established using experimental data. The formulated optimal thrust allocation problem is solved using Mincon (Sequential Quadratic Programming) and SA (Simulated Annealing) optimization algorithm. The percentage savings in total power consumption for thruster system using the SA method as compared to Mincon method is 50.6 %.