Ghulam Ishaq Khan Institute of Engineering Sciences and Technology

About: Ghulam Ishaq Khan Institute of Engineering Sciences and Technology is a education organization based out in Topi, Pakistan. It is known for research contribution in the topics: Thin film & Quantum efficiency. The organization has 618 authors who have published 940 publications receiving 10674 citations.

Nuclear inputs of key iron isotopes for core-collapse modeling and simulation

Abstract: From the modeling and simulation results of presupernova evolution of massive stars, it was found that isotopes of iron, $^{54,55,56}$Fe, play a significant role inside the stellar cores, primarily decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture processes thereby reducing the pressure support. The neutrinos produced, as a result of these capture processes, are transparent to the stellar matter and assist in cooling the core thereby reducing the entropy. The structure of the presupernova star is altered both by the changes in $Y_{e}$ and the entropy of the core material. Here we present the microscopic calculation of Gamow-Teller strength distributions for isotopes of iron. The calculation is also compared with other theoretical models and experimental data. Presented also are stellar electron capture rates and associated neutrino cooling rates, due to isotopes of iron, in a form suitable for simulation and modeling codes. It is hoped that the nuclear inputs presented here should assist core-collapse simulators in the process of fine-tuning of the $Y_{e}$ parameter during various phases of presupernova evolution of massive stars. A reliable and accurate time evolution of this parameter is a possible key to generate a successful explosion in modeling of core-collapse supernovae.

A new proposed hierarchy for renewable energy generation to distribution grid integration

Abstract: This paper presents a new hierarchy about the study of renewable energy generation, its transmission, energy storage and adding this power to distribution grid level. Simulation are verifying the feasibility and working. The main purpose of this study is to propose a feasible solution to replace fossil fuel energy sources to renewable energy sources without changing current working distribution grids setup. This paper will describe main components of this hierarchy including DC-DC converters, DC transmission, energy storage devices and grid integration. DC-DC converters are converting generated voltages to high voltages to transmit them on DC transmission line. Similarly a DC-DC step down converter is being used for step down purpose for using transmission line voltage to low level voltage for energy storage purpose and for grid integration on distribution side. DC-AC inverter is using old distribution grid signal as sample and converter DC into AC according to it. Simulation results verify the efficient working of all converters and completely stable system.

Crystallization kinetics of AlF3-based glasses doped with rare earth ions

Abstract: Different concentrations of NdF 3 , PrF 3 , and PrF 3 , codoped with YbF 3 , ranging from 0.25 to 2.0 wt%, have been added to an AlF 3 -base glass with composition (mol%) 30.2AlF 3 –10.6BaF 2 –20.2CaF 2 –8.3YF 3 –3.5MgF 2 –3.8NaF–13.2SrF 2 –10.2ZrF 4 . The Avrami exponent, n , and activation energy, E , for the base glass, as well as the doped glasses, have been calculated by analyzing the differential scanning calorimetry curves, according to the amended Ozawa–Chen and Augis and Benett equations. In light of these results, we observe that the introduction of suitable amounts of rare-earth ions improved the thermal stability of the base glass.

Identifying performance issues based on method invocation patterns of an API

Abstract: Software systems use many third party libraries by invoking their APIs. A software system may potentially use an API in an inefficient manner, for example, by creating unnecessary or a large number of short-lived objects. This can cause performance degradation in terms of memory usage and latency in critical applications. In this paper we use an object invocation model based on object creation and their method invocations from different code locations. We use a framework to extract the model features from a running software system. The extracted features are then used in a clustering based mechanism to identify problematic code locations within the software system. We demonstrate our approach by analyzing Java Collection API objects in a Java-based open source editor JEdit. We have successfully identified interesting code locations and discussed their impact on software performance.