Microstructure and texture evolution of Pure magnesium during ecae

Initially hot rolled commercially pure magnesium and having a basal texture was deformed by Equal Channel Angular Extrusion (ECAE). ECAE was carried out up to 4 passes in a 90° die following three different routes (A, Bc and C) at a temperatures of 523 K. Systematic analysis of microstructures, grain size distributions, texture and grain boundary character distributions was carried out using electron back scattered diffraction in field emission gun scanning electron microscope in the transverse plane. In addition to significant reduction in grain size, strong fiber texture inclined at an angle ~ 45o from the extrusion axis formed in the material. Texture was also analyzed by orientation distribution function (ODF) and compared vis-à-vis shear texture. A significant amount of dynamic recrystallization occurred during ECAE, which apparently did not influence the deformation texture

From the macroscopic to the microscopic: some scientific insights

The full report in which this chapter appears is in ORE: http://hdl.handle.net/10871/1416

Особенности реализации режимов пониженного энергопотребления при внедрении распределенной системы управления теплопотреблением здания

An integrated model, consisting of a distributed automatic control system, building heating system and individual heating unit is designed. The model is based on the Simulink application. The conducted research allowed to reveal features of heating system operation with distributed control system. The results of comparison the climatic variables of control rooms are presented. The conclusions about the possibility of increasing the energy efficiency of heating system in the implementation of distributed control systems are presented

Clinical Profile and Short-term Outcome of Heart Failure Patients in a Tertiary Hospital in Kaski, Nepal: A Cross-sectional Study

Introduction: Heart failure is one of the leading causes of hospitalization. The aim of this study was to evaluate the epidemio-clinical profile and short-term outcome of hospitalized heart failure patients in a tertiary care hospital. Methods: This descriptive cross-sectional study was conducted at Pokhara Academy of Health Sciences, Kaski, Nepal from October 1, 2021 to January 31, 2022. All the hospitalized heart failure patients aged 18 years or above were included. Relevant history, examination, laboratory, and pertinent findings were noted.  Descriptive statistics were used for qualitative and quantitative data. Paired t-test was used for the comparison of pre-and post-hospitalization data. A p-value <0.05 was taken for statistical significance. Results: There were a total of 116 patients (65.5% females) with a mean age of 64.20 ± 16.35 years. Most of them had shortness of breath (97.4%) and orthopnea (72.4%) and presented with pedal/sacral edema (81.9%) and bilateral basal crepitations (69.8%) in the chest. Heart failure with preserved ejection fraction was the most prevalent (61.2%) type and dilated cardiomyopathy (27.6%) was the commonest etiology of heart failure. The median duration of hospitalization was five days and the in-hospital mortality was 2.6%. Loop diuretics and vasodilators (angiotensin-converting enzyme inhibitor/angiotensin receptor blocker) were the most commonly used medications. Conclusions: Dilated cardiomyopathy was the most common etiology and heart failure with preserved ejection fraction was the predominant type of heart failure. With a short length of stay and low in-hospital mortality, the short-term outcome was good

Improvements of machinability of aerospace-grade Inconel alloys with ultrasonically assisted hybrid machining

Aerospace-grade Ni-based alloys such as Inconel 718 and 625 are widely used in the airspace industry thanks to their excellent mechanical properties at high temperatures. However, these materials are classified as ‘difficult-to-machine’ because of their high shear strength, low thermal conductivity, tendency to work-harden and presence of carbide particles in their microstructure, which lead to rapid tool wear. Machining-induced residual stresses in a machined part is an important parameter which is assessed since it can be used to evaluate overall structural resilience of the component and its propensity to fatigue failure in-service. Ultrasonically assisted turning (UAT) is a hybrid machining technique, in which tool-workpiece contact conditions are altered by imposing ultrasonic vibration (typical frequency ~ 20 kHz) on a tool’s movement in a cutting process. Several studies demonstrated successfully the resulting improvements in cutting forces and surface topography. However, a thorough study of UAT-induced residual stresses is missing. In this study, experimental results are presented for machining Inconel 718 and 625 using both conventional turning (CT) and UAT with different machining parameters to investigate the effect on cutting forces, surface roughness and residual stresses in the machined parts. The study indicates that UAT leads to significant cutting force reductions and improved surface roughness in comparison to CT for cutting speeds below a critical level. The residual stresses in machined workpiece show that UAT generates more compressive stresses when compared to those in CT. Thus, UAT demonstrates an overall improvement in machinability of Inconel alloys

Modelling strain localization in Ti-6Al-4V at high loading rate: a phenomenological approach

A phenomenological approach based on a combination of a damage mechanism and a crystal plasticity model is proposed to model a process of stain localization in Ti-6AI-4V at a high strain rate of 103 s-1. The proposed model is first calibrated employing a 3D representative volume element model. The calibrated parameters are then employed to investigate the process of onset of strain localization in the studied material. A suitable mesh size is chosen for the proposed model by implementing a mesh-sensitivity study. The influence of boundary conditions on the initiation of the strain localization is also studied. A variation of crystallographic orientation in the studied material after the deformation process is characterized, based on results for different boundary conditions. The study reveals that the boundary conditions significantly influence the formation of shear bands as well as the variation of crystallographic orientation in the studied material. Results also indicate that the onset of strain localization can affect considerably the material’s behaviour