Computational Fluid Dynamics (CFD) is a useful tool that enables highly cost-effective numerical solutions for the problems related to fluid flow phenomena, which in turn results in the state-of-the-art product designs in a variety of engineering sectors. CFD has made remarkable progress due to continuous growth in computing capabilities. Further increase in the computing power urges the computational scientists for even more detailed and in-depth analyses. Better understanding of the flow phenomena, however, requires higher order/resolution solutions, which in turn requires more and more computing power due to increase in the number of degrees of freedom. The present thesis is to contribute in the endeavor of addressing these two challenges, i.e., to provide higher order numerical solutions in fluid mechanics and to fulfill the demand of computing power. The first objective is addressed by presenting a high order flow solver for compressible fluid flow problems and the second objective is addressed by developing a high performance parallel implementation of the flow solver. The present work is aimed at developing a scalable and efficient parallel program based on a high order discontinuous Galerkin (DG) method with Taylor series basis for the compressible Euler and Navier-Stokes equations on unstructured meshes. The numeri- cal scheme is capable of efficiently simulating the physics of the flow problems consid- ered, including subsonic and transonic compressible inviscid flows around two well known benchmark airfoils. The parallel code employs the DG method for the space discretiza- tion of the governing equations to obtain a semi-discrete form and various explicit and implicit schemes for time integration of this semi-discrete form. The explicit time inte- gration scheme is based on three-stage third-order Total Variation Diminishing (TVD) Runge-Kutta (RK) method. The implicit time integration scheme for the Euler equa- tions is based on Backward Euler scheme. The resulting system of algebraic equations iis solved using a variety of so-called matrix-free parallel linear solvers, including Symmet- ric Gauss-Seidel (SGS) method, Lower-Upper Symmetric Gauss-Seidel (LUSGS) method and Generalized Minimum Residual (GMRES) method preconditioned with LUSGS (i.e., GMRES+LUSGS). In this work, a parallel p-multigrid solver for the Euler equations is also presented. Unlike the other p-multigrid solvers where the same time integration scheme is used on all the approximation levels, the present two-level p-multigrid solver uses the Runge-Kutta scheme as the iterative smoother on the higher level approximation, and the matrix-free GMRES+LUSGS method as the iterative smoother on the lower level approximation in an attempt to significantly reduce the computer memory requirements. In this thesis, inviscid flow computations are accurate up to the fourth order of polynomial approximation whereas the viscous flow computations are accurate up to the third order of polynomial approximation. The parallel DG flow solver is based on distributed memory programming model, making use of the message passing approach for communications among the parallel processes. Two kinds of so called commodity parallel systems are used as the platform for per- forming parallel computations. The first kind of parallel systems are the clusters in which the worker nodes are interconnected using some networking technology. The other kind of parallel systems are the multicore SMP machines. The parallelization is based on Single Program Multiple Data (SPMD) parallel programming model that has been em- ployed by making use of a computational domain partitioning technique and the de-facto industry standard Message Passing Interface (MPI) library for inter-process communica- tions. Favorable parallelization characteristics of the discontinuous Galerkin method have also been exploited by hiding the communications behind the computations. The parallel performance of the developed code, in terms of scaling of the speedup with respect to the number of processes, is demonstrated.
This research is entitled Analysis Leverage, Good Corporate Governance (GCG), and Profit Quality on Earnings Quality in Companies listed on the Indonesia Stock Exchange (IDX) and indexed by the Jakarta Islamic Index (JII). This research was conducted because the previous research was mostly conducted on companies listed on the Indonesia Stock Exchange, while only a few were conducted on companies indexed by the Jakarta Islamic Index so that research was very open, by adding variables namely profit quality and earnings quality. The purpose of this study was to determine the direct effect on earnings quality in companies indexed by the Jakarta Islamic Index.The population of this study are companies listed and indexed by the Jakarta Islamic Index on the Indonesia Stock Exchange, while the samples used are financial reports for 2018-2020. The sampling method was carried out using purposive sampling method. The number of samples obtained was 90 company data listed on the Indonesia Stock Exchange and indexed by the Jakarta Islamic Index (30 companies and an observation period of 3 years, namely 2018-2020). The data analysis method used by the author is multiple linear regression analysis method both partially and simultaneously using SPSS 23. The results showed that partially leverage has a significant effect on earnings quality, good corporate governance has a significant effect on earnings quality and earnings quality has a significant effect on earnings quality, while simultaneously showing that leverage, good corporate governance, and earnings quality have a significant effect on earnings quality.
While reading comprehension is an integral part of English language teaching, it should aim to equip students with basic strategies to help them construct meaning from English texts. However, through my personal experiences at different levels as an English teacher and from the evidences of the reconnaissance of this study, it emerged that reading comprehension was a challenging issue among students in the context of this particular study. The study was conducted in the context of a private school in Gilgit Baltistan. The purpose of the study was to improve grade eight students' English reading comprehension skills by using Reciprocal Teaching Approach (RTA). RTA is embedded in four basic strategies of reading, such as predicting, questioning, clarifying and summarising. Data for the study was collected from a sample of six participant students and the subject teacher through qualitative tools like observation, interview, pre and post-tests, reflective journals and field notes. The data of the study was analysed at three stages of the action research that is, reconnaissance, the action research and post-action research stage. Analysis of the gathered data revealed that there was a reasonable improvement in students' understanding of the reading strategies. By the end of the study, they were found to be more proficient, skilful and self-reliant in reading. Thus, it revealed that the strategies of RTA were helpful in enhancing the skills of six students of grade 8 in the context of the study. The study recommends future researchers to conduct separate action research studies on each of the four strategies of RTA at different grades in different contexts. Such a study would help the future researchers to investigate how a particular strategy can be helpful in enhancing students' reading skills in English. The study also recommends replicating the same study in a public school context.