3 research outputs found
Bending and compressive strength of lattice structures manufactured by SLM
No full textLAUREA MAGISTRALEQuesto lavoro di tesi tratta principalmente di strutture reticolari f2-BCC e f2-FCC-L, ottenute tramite l’utilizzo di additive manufacturing della lega AlSi10Mg utilizzando la tecnica del Selective Laser Melting (SLM). Queste due tipologie di strutture micro-cristalline hanno migliori proprietà meccaniche a parità di peso, migliore rigidezza e buone caratteristiche di resilienza. Svariate analisi FEM sono state condotte considerando i provini costituiti dai meta-materiali tenendo anche conto dei vari difetti come porosità e vuoti. Tutte le difettosità derivanti dall’utilizzo dell’additive manufacturing sono state considerate utilizzando il modello di danneggiamento duttile di Gurson Tveergard Needleman (GTN). Il modello GTN nell’analisi FEM è stato comparato con test sperimentali in compressione e in flessione a tre punti. L’introduzione di una sezione nel piano medio nel modello di flessione a tre punti (spessore uguale al diametro della struttura), ha portato a un miglioramenti dei risultati.Tutti gli esperimenti sono stati campionati mediante l’utilizzo della digital image correlation (DIC), confrontata poi con la massima deformazione nella sezione di massima freccia e con i risultati dei provini portati a rottura.Un’analisi tomografica è stata utilizzata per analizzare l’effettivo reticolo cristallino presente nel reticolo f2-BCC e f2-FCC-L. La geometria, la dimensione della struttura, la porosità, i vuoti e anche l’analisi del modello sperimentale del reticolo f2-BCC sono stati analizzati utilizzando la tomografia. Successivamente il modello reale è stato migliorato considerando le limitazioni tecnologiche.Infine, l’effetto dinamico è stato studiato tramite modelli FEM, per capirne le proprietà, utilizzando il modello GTN. L’effetto dinamico è evitato tramite l’aumento del tempo, quindi tramite la riduzione del coefficiente di carico a parità di spostamento.This work study is majorly about lattice structures (f2-BCC and f2-FCC-L), by means of additive manufacturing for AlSi10Mg using selective laser melting (SLM). These two micro lattice structures have better strength to weight ratio, greater stiffness, and good energy absorption characteristics. FEM analysis is done considering meta materials to build the sample considering the various defects like voids and porosity. All the defects from additive manufacturing are considered while using ductile damage model of Gurson Tveergard Needleman (GTN). GTN model in FEM analysis is made and compared with experimental test for three-point bending and compression analysis. By introducing a middle plane section in the three-point bending model (thickness equal to the diameter of strut) improves the result. All the experiments are captured through digital image correlation (DIC) to check whether the strain concentration of strut in the maximum displacement area and the results of the ruptured experimental samples is compared with DIC results. Tomography is used to analyze the real lattice model of f2-BCC and f2-FCC-L. The geometry, strut dimension, porosity, voids as well as the analysis of the experimental f2-BCC model is analyzed using tomography. Thus, the real model has been improved considering manufacturing limitations. Finally, the dynamic effect in FEM model is studied to understand it’s behavior by using the GTN model. The dynamic effect is avoided by increasing the time thus reducing the load rate with constant displacement
Topics in statistical finance
No full textThis thesis is divided into three parts. The first part investigates the presence of long term dependence in stock price data via a permutation test based on the correlation structure of the underlying stock prices. These tests reveal the short term nature of stock price dependence structure. The second part extends
Ramprasath and Singh(2007)'s `statistical options' to define a group of American type options based on robust estimators of location. The payoff functions of these path dependent options are based on a new set of stochastic processes which are defined using various robust estimators of location. The asymptotic distributional behavior of these new processes is ascertained which in turn is used in pricing
the options. Markov Chain Monte Carlo (MCMC) methods were used to compute the prices of the statistical options. The third part explores a stock price model parameter estimation problem and interprets a growth rate parameter.Ph.D.Includes bibliographical references (p. 81-83)
Knowledge attitude and practice towards prevention and early detection of chronic kidney disease among high risk patients
No full textBackground: It is well recognized that chronic kidney disease (CKD), if left, untreated would slowly progress to end-stage renal disease (ESRD)., A targeted approach is to enhance the knowledge of CKD among the public, especially in high risk population, and encourage them to practice a healthy attitude and practice that may help in early detection and thereby better management of CKD. Such a study to assess the baseline data has not been done in India. Aims and Objectives: To inculcate the knowledge attitude and practice towards prevention and early detection of CKD among high risk patients attending a tertiary care centre. This Observational study was carried out on all patients with diabetes and/or hypertension attending General medicine out-patient or in-patient in a given period of time. Patients more than 18 years of age with diabetes and/or hypertension were included while patients with chronic kidney disease were excluded. Methodology: A standard questionnaire obtained from an author of similar study is given to patients fulfilling the inclusion criteria. Is this National Kidney Foundation's Kidney Disease Outcome Quality Initiative (KDOQI)? If so mention it. 
