Numerical and experimental investigations of the acoustic standing wave resonator, pump, and micropump

The interactions of acoustic waves and thermoviscous fluids in closed cavities lead to some important physical phenomena such as, linear and nonlinear acoustic standing waves, and acoustic streaming which are very important in a wide range of engineering applications. The present dissertation is focused on the detailed investigation of standing wave dynamics in closed cavities. As a part of this research, novel numerical and experimental techniques are developed to analyze different phenomena caused by acoustic-fluid interaction. Using these techniques, the behavior of pressure, acoustic and streaming velocity fields inside the standing wave resonator, as well as the valveless acoustic pump and micropump are investigated. A new sixth-order accurate compact finite difference method for solving the Helmholtz equation with Neumann boundary conditions is developed. This scheme showed a better performance at higher wave numbers than the finite element method. A new fourth-order numerical scheme is also developed for solving highly nonlinear standing wave equations with no restriction on nonlinearity level and type of fluid. For highly nonlinear waves, the simulation results show the presence of a wavefront that travels along the resonator with very high pressure and velocity gradients. The slopes of the traveling velocity and pressure gradients, and the asymmetry in the pressure waveform are higher for CO 2 than those for air. The spatial and temporal variations of the nonlinear pressure and particle velocity fields inside a resonator are experimentally investigated at different frequencies and intensities. The effects of the excitation frequency and displacement on the streaming structure are also studied. It is found that, the classical streaming is not developed for Re s 1 50. Acoustic streaming patterns are also found to be significantly affected by transverse temperature gradient. A valveless acoustic standing wave pump is developed and the velocity fields inside this novel pump are analyzed. It is found that, the net flow rate of the pump increases with an increase in the pressure amplitude. The behavior of a novel acoustic micropump is also studied at a high frequency. The effect of the diffuser geometry on the pump performance is investigated. The results show that the maximum diffuser efficiency is achieved at the diffuser-nozzle element's half-angle of approximately 45

Granting Asylum to Truth-Seekers from the perspective of Qur'an

From the very beginning of the Islamic era, it has happened many times that a number of polytheists, in response to their call of nature, applied for a voluntary listening to the Quran. This phenomenon, which is called "Asylum-Seeking of Polytheists" in the Quran, was considered as a unique and incomparable event throughout the Islamic history in the field of propagation of the religion of Islam for non-Muslims. Asylum means seeking refugee by the idolaters. In this case, it is obligatory for the Muslims to provide the ground for realizing this important issue, to remove the possible obstacles and to accept the asylum-seeker pagan and provide him with sufficient verses and proofs so that he may be guided to the right path.In this article, while giving an objective explanation of this issue, as well as referring to examples of "granting asylum to truth-seeking pagans", we study the practical solutions in this regard, which are presented for the first time and, if realized, good conditions would be created for non-Muslims. Obviously, this kind of asylum is a cultural and religious asylum and not a political asylum

Plasma Spray Process Parameters Configuration using Sample-efficient Batch Bayesian Optimization

Recent work has shown constrained Bayesian optimization to be a powerful technique for the optimization of industrial processes. In complex manufacturing processes, the possibility to run extensive sequences of experiments with the goal of finding good process parameters is severely limited by the time required for quality evaluation of the produced parts. To accelerate the process parameter optimization, we introduce a parallel acquisition procedure tailored on the process characteristics. We further propose an algorithm that adapts to equipment status to improve run-to-run reproducibility. We validate our optimization method numerically and experimentally, and demonstrate that it can efficiently find input parameters that produce the desired outcome and minimize the process cost

Advanced Manufacturing Configuration by Sample-efficient Batch Bayesian Optimization

We propose a framework for the configuration and operation of expensive-to-evaluate advanced manufacturing methods, based on Bayesian optimization. The framework unifies a tailored acquisition function, a parallel acquisition procedure, and the integration of process information providing context to the optimization procedure. \cmtb{The novel acquisition function is demonstrated, analyzed and compared on state-of-the-art benchmarking problems. We apply the optimization approach to atmospheric plasma spraying and fused deposition modeling.} Our results demonstrate that the proposed framework can efficiently find input parameters that produce the desired outcome and minimize the process cost.Comment: Accepted for IEEE RA-L. 8 pages, 6 figures. arXiv admin note: text overlap with arXiv:2103.1388

A study on Quraniyyun (Quranism) representatives and references

MakaleKur'âniyyûn, hadîsin hücciyetini tamamen reddeden veya hadîsleriçin gereken önemi vermeyen kimselere verilen addır. Bu kimseler, itikâd ve amel için sadece Kur’ân’ı yeterli görmektedirler. Bu makalede söz konusu ekolün bazı ileri gelenleri ve kaynakları tanıtılmaktadır. Bu çalışmada 8 Şia mezhebine mensup Kur'âniyyûn ve 16 Ehl-i Sünnet’e mensup Kur'âniyyûn’lardan seçilerek faaliyetleri ve eserleri ile birlikte tanıtılmaktadır. Daha sonra ise Kur'âniyyûn ile ilgili 18 kitap, 22 makale ve 9 tez çalışması bilgisi verilmektedir.Quraniyyun (Quranism) is a name given to the ones who do not accept the hadiths as evidence and who do not give essential importance to hadiths. Those people accept only the Quran as evidence in theological and practical issues. In this article, some pioneers and sources of such ecole are introduced. Furthermore, in this work, 8 Shii Quraniyyun and 16 Quraniyyun from Ahli Sunnah are introduced with their works and activities. Moreover, information about 18 books, 22 articles, and 9 thesis which are related to Quraniyyun is give

Investigating the viewpoints of central libraries' managers of governmental universities about users' access to dissertations

Objective: The purpose of the present study is to identify the viewpoints of central libraries' managers of governmental universities which are supervised by two ministries of Science, Research and Technology, and Health and Medical Education regarding users' access to dissertations. Methodology: As a descriptive survey, all Managers of the central libraries of governmental universities which are supervised by two ministries of Science, Research and Technology, and Health and Medical Education were participated in the study. Considering limited number of population members, sampling was not used in this study. The data gathering tool was a researcher-made questionnaire. Findings: The findings showed that central libraries' managers of the universities have different viewpoints on access to dissertations. The managers'' points of view about the levels of access to the dissertation are different for users within or outside the university campus so they think that it's better for users to have access to the full text within the university, and they have access to only bibliographic information outside the university. In addition, they agree with accessing to parts of the dissertations (not full text) in both printed and/or electronic version on charge. Managers agreed with the "PDF" format among different electronic versions. Originality: Despite the importance of recognizing the attitude of library managers towards determining the policy of making dissertations available to library users, this issue has not been studied till now. This article addresses this important issue