Estimation of Parameters and Design of a Path Following Controller for a Prototype AUV

In order to improve the performance of autonomous underwater vehicles (AUVs) deployed in different applications such as oceanographic survey, search and detection tasks in a given area necessitates the development of an appropriate path following controller which offers a precise and rapid control of the AUVs’ control surfaces and propeller system. In order to design such a vehicle control system, there is a need for good approximation of the vehicles static and dynamic model. Based on a combination of theoretical and empirical data, it can provide a good starting point for vehicle control system development as well as an alternative to the typical trial-and-error methods used for controller design and tuning. As there are no standard procedure for AUV modeling, the simulation of each autonomous underwater vehicle (AUV) represents a new challenge. This thesis describes the development of a six degree of freedom, non-linear simulation model for the prototype AUV. In this model, all the forces which strongly affect the dynamic performance of an AUV such as the external forces and moments resulting from hydrostatics, hydrodynamics, lift and drag, added mass, and the control inputs of the AUV propeller and fins are all defined in terms of vehicle coefficients. Computational Fluid Dynamics along with empirical formulas have been applied to determine the hydrodynamic coefficients of the AUV. In order to model the behavior of the AUV as closely to the real-world system as possible, the equations used for determining the coefficients, as well as those describing the AUVs’ motions were left in non-linear form. Simulation of the AUV motion was achieved using numerical integration techniques of the equations of motion based on the derived coefficients. From the simulation, of the AUV model, results observed led to the development of a controller for the prototype AUV. Sliding Mode Controller was chosen as the desired controller because of its definitive advantages over the PID controller, some of which are the straightforward firmware implementation, use of discrete decision rules which allows the controller to function in hybrid feedback configuration and the fact that it does not suffer from issues related with the drift in controller signal output with time, i.e. latency issues for real time applications. The developed model of the prototype AUV was decoupled into two separate parts namely Heading control and Depth control. State Space Model for each part was derived and a Sliding Mode controller was developed based on the required dynamics of each part. Simulations of the AUV model integrated with Sliding Mode Controller (SMC) was carried out to determine whether the controller was able to direct the motion of the prototype AUV along the desired path, i.e. the level of accuracy of the prototype AUV in path following task

Building Organic Institutions in Nepal: Transformational Organic Leadership Perspectives

It is really challenging to transform the conventional trends of farming and consumption trends in Nepal. On the other hand, there is an opportunity to make use of the traditional ecological knowledge of the indigenous farmers for augmenting newly emerged organic farming practices. In this scenario, transformational organic leadership is needed to build organic institutions in Nepal

Mortality pattern of Nili-Ravi buffaloes under organised herd in India

The objective of the study was to find out the mortality pattern of Nili-Ravi buffaloes under organised herd in tropical climate. An investigation was carried out on mortality records of 318 Nili-Ravi buffaloes maintained at Central Institute for Research on Buffaloes, Regional Station-Bir Dosanjh, Nabha, Patiala, Punjab over a period of 16 years (1994-95 to 2009-10). Each year was divided into three seasons i.e. hot-dry (March-June), hot- humid (July-October) and cold (November to February). Sex of animals was divided into male and female group. The age of animals were grouped into eight categories viz. up-to 30 days (d), 31-60 d, 61-90 d, 91-180 d, 181-365 d, 366-1095 d, 1096-3650 d and more than 3651 d. The causes of mortality based on post-mortem findings were classified into twelve classes e.g. major respiratory diseases (MARD), minor respiratory diseases (MIRD), major digestive disorders (MADD), minor digestive disorders (MIDD), cardiovascular diseases (CVD), parasitic diseases (PAD), infectious diseases (ID), musculoskeletal diseases (MSD), urogenital/reproductive diseases (UGD/RD), neurological disorders (ND), nutritional/metabolic/production diseases (NMD) and miscellaneous disorders (MD). Majority of the buffaloes died in the months of July to October. About two third of the buffalo deaths occurred before one year of their age. Major respiratory diseases followed by major digestive disorders and cardiovascular diseases were the predominant causes of buffalo death under organised herd. This information will be beneficial in reducing buffalo mortality through adopting proper herd health programme of organized buffalo herd

Effect of Hygrothermal Treatment on the Tensile Properties of Hot-Pressed Jute Fibre Composites

The growing environment awareness demands the use of nature fibres as reinforcement materials in commercial. The natural fibres however are hydrophilic in nature and their composites undergo environmental degradation during service. Hygrothermal conditioning on as received jute fabric at different temperatures of hotpress have been studied in the present investigation. These composites are usually subjected to various loading conditions. Therefore, an attempt has been made to study the tensile properties of the composites. Fractography studies were carried out to study the fracture surface under SEM. It is noticed that the major mode of failure is due to fibre pullout and matrix cracking. The result from the hygrothermal studies shows the decrease in strength values of the composites on prolong exposure to humid environment.

The G protein-coupled receptors in the pufferfish Takifugu rubripes

<p>Abstract</p> <p>Background</p> <p>Guanine protein-coupled receptors (GPCRs) constitute a eukaryotic transmembrane protein family and function as “molecular switches” in the second messenger cascades and are found in all organisms between yeast and humans. They form the single, biggest drug-target family due to their versatility of action and their role in several physiological functions, being active players in detecting the presence of light, a variety of smells and tastes, amino acids, nucleotides, lipids, chemicals etc. in the environment of the cell. Comparative genomic studies on model organisms provide information on target receptors in humans and their function. The Japanese teleost Fugu has been identified as one of the smallest vertebrate genomes and a compact model to study the human genome, owing to the great similarity in its gene repertoire with that of human and other vertebrates. Thus the characterization of the GPCRs of Fugu would provide insights to the evolution of the vertebrate genome.</p> <p>Results</p> <p>We classified the GPCRs in the Fugu genome and our analysis of its 316 membrane-bound receptors, available on the public databases as well as from literature, detected 298 GPCRs that were grouped into five main families according to the GRAFS classification system (namely, Glutamate, Rhodopsin, Adhesion, Frizzled and Secretin). We also identified 18 other GPCRs that could not be grouped under the GRAFS family and hence were classified as ‘Other 7TM’ receptors. On comparison of the GPCR information from the Fugu genome with those in the human and chicken genomes, we detected 96.83% (306/316) and 96.51% (305/316) orthology in GPCRs among the Fugu-human genomes and Fugu-chicken genomes, respectively.</p> <p>Conclusions</p> <p>This study reveals the position of pisces in vertebrate evolution from the GPCR perspective. Fugu can act as a reference model for the human genome for other protein families as well, going by the high orthology observed for GPCRs between Fugu and human. The evolutionary comparison of GPCR sequences between key vertebrate classes of mammals, birds and fish will help in identifying key functional residues and motifs so as to fill in the blanks in the evolution of GPCRs in vertebrates.</p