The squeezing flow occurs due to the action of normal stresses that originate from different configurations of the plates movement. This context may resound to be profoundly simple from the onset, but has important applications in the areas of engineering, physics, biology, and material sciences. In the past few years, the study of rheometric properties of fluids has garnered profound attention due to its vast industrial applications. Examples include modeling of lubrication systems involved in squeezing of fluids, compression and injection molding processes of metals and polymers, hydrodynamical tools and machines, modeling of chewing and eating, and modeling of the functions of heart valves and blood vessels. As a result, it is a major focus of researchers working in fluid mechanics. This thesis presents the theoretical analysis of unsteady squeezing flow of Newtonian and nonNewtonian fluids between two parallel plates under various boundary conditions. Observation of the squeezing behavior and associated rheological properties of the fluid can be interpreted using various analytical and numerical techniques. Due to the simplicity of the geometry involved, these can also be realized experimentally, while obtaining measurements from sensors or feedback control loops. For the analytical and numerical approach, the squeeze behavior is based on various models like Newtonain, Casson, Power law etc which leads to various differential equations. For this purpose, the thesis goes into a detailed investigation of the rheological properties of fluid flow with various boundary conditions and fluid types. These properties include velocity profiles, pressure distribution, and skin-friction. This investigation starts initially with the analysis of an unsteady flow of Newtonian fluid squeezed between two circular plates with slip and no-slip at the boundaries. It then gradually extends to higher order problems and different boundary conditions. This includes firstly a case involving squeezing of an incompressible Newtonian fluid passing through porous medium, followed by another case involving squeezing of non-Newtonian Casson fluid having magnetohydrodynamical effect, and passing through porous medium. The Casson fluid model is further extended to analyze the slip effect at fluid-solid interface. All these cases are dealt in separate chapters. In all cases, similarity transformations are used for the conversion of PDEs to highly nonlinear ODEs. Various analytical techniques like Optimal Homotopy Asymptotic Method (OHAM), Homotopy Perturbation Method (HPM), Homotopy Perturbation Laplace Method (HPLM), and numerical schemes like Explict and Implicit Runge Kutta Method of order 4 (ERK4 & IRK4) and NDSolve (Mathematica Solver) are applied for the solution and analysis of the modeled problems. Convergence and validity of the obtained analytical solutions are checked by finding various order solutions along with residual errors, and comparing it with numerical results. In addition, the thesis also proposes a novel adaptation to a scheme that combines tradiiii tional perturbation techniques with Homotopy using a Laplace transform. This scheme is applied to a problem of squeezing flow of an incompressible Newtonian fluid through porous medium, and tested against various analytical and numerical schemes.
اسرار خمار ہوا کے ہاتھوں میں چھالے پڑے ہوئے تھے خوشبو کے ہالے میں طاق تھا پروانوں کے طواف سے! چاندنی میں سرخ سبز آیتوں کے انکشاف سے! جمال فسوں کے دلفریب در کھل رہے تھے دل کی شرطوں میں دف بج رہی تھی زمان عصر کے زاویوں میں! اک ناقہ خمار میں ڈوبی چل رہی تھی شبنمی چاندنی میں اسرار خواب ڈھل رہے تھے خوشبو کی بدلتی تاثیر میں! صوفیوں نے بھی باب وفا کے قریب بزم سجا رکھی تھی آباد حویلیوں سے! لذت معنی کے علمدار۔۔۔سبز موسم کے راز داں آ رہے تھے شفیق مسافتوں کے۔۔۔زلفہ اور صودابہ کی۔۔۔! دھڑکنوں کے راز کھل رہے تھے قدیم خیالوں کا پتہ دیتے ہوئے! کئی آہو سبز ساحلوں کی طرف نکل رہے تھے ستاروں کی چال اور زائچے بدل رہے تھے۔۔۔۔
Foreign direct investment plays a key role in economic development of all countries. Because of its enormous importance, a large number of empirical studies has focused on finding out the factors determining foreign direct investment. Level of human capital development is one of the major factors influencing foreign inflows. However, earlier studies examining impact of human capital on foreign investment inflows has majorly used literacy rate, school enrolment and government spending on education as its proxies. This paper also examines the impact of human capital as determinant of foreign direct investment. Contrary to earlier empirical studies, it uses cognitive skills as proxy for human capital. Cognitive skills measure the quality of education instead of literacy rate or government spending on education as proxy for human capital. Results indicate that human capital has significant positive effect on foreign direct investment for sample countries. This result is robust to disaggregated data for developed and developing countries. Other factors that determine foreign direct investment inflows are inflation, capital account openness, trade account openness and real income. Based on empirical results, it is recommended that the relevant authorities must make human capital as part and parcel of strategies aimed at augmenting economic growth in the country. There is also a lesson for a developing country like Pakistan to focus more on quality of education instead of school enrolment or education spending for attracting foreign direct investment to boost economic activity (J.E.L Classification Codes: O4, O15, P22).
Rice is one of the most important staple foods on which more than half of the global population de- pends as a source of their calories. Pakistan being one of the world’s major rice producing countries produces rice not only for its domestic needs but also for export to earn foreign exchange. With the current trends for functional foods and nutraceuticals, growing need exists to explore local rice cul- tivars for biochemical composition and nutrient specificity to enhance the share of rice in trade mar- ket and to benefit consumer’s health. The primary objective of the present research was to character- ize selected varieties of rice (Oryza sativa L.) and its by-product (rice bran) for the important nutri- ents, high value-components and antioxidant attributes. The rice varieties most commonly cultivated in Pakistan were analyzed for the quality- oriented physiochemical and nutritive attributes such as moisture, ash, crude fiber, carbohydrates, lipids, proteins and minerals etc. Proximate analysis re- vealed that Pakistani varieties, especially, Basmati rice, contain appreciable amounts of important nutrients such as carbohydrates, protein, fat, crude fiber and minerals. Extraction for antioxidant components from rice and rice bran was carried out by employing six solvents; methanol (100%,80%), ethanol (100%,80%) and isopropanol (80%,100%) and two extraction techniques; or- bital shaker and sonication-assisted orbital shaker. Overall, best extraction yields of antioxidant components were obtained with 80% isopropanol and 80% methanol using sonication-assisted or- bital shaker. The antioxidant activity of the tested varieties of rice and rice bran was assessed using various in vitro antioxidant essays e.g. estimation of total phenolic contents (TPC), 2,2-diphenyl-1- picrylhdrazyl (DPPH) free radical-scavenging capacity, reducing power and ferrous ion-chelating activity. Present study revealed that tested Pakistani rice varieties have considerable potential for total phenolics and radical scavenging activity. The profiles of carbohydrates, fatty acids, sterols, amino acids, tocopherols and γ-oryzanol compounds were studied by using state-of-the-art spectro- scopic and chromatographic techniques such as UV/Vis spectrophotometer, HPLC, GC, GC-MS etc., where applicable. Among rice varieties tested sixteen amino acids were detected with glutamic acid, arginine, leucine and aspartic acid as the major components. GC analysis of the fatty acids composition depicted C18:1 and C18:2 as the major fatty acids of rice varieties. GC and GC-MS analysis revealed the presence of β-sitosterol, stigmastenol and campesterol as the main phytosterol components. HPLC analysis of the tocopherols and γ-oryzanol showed the distribution of α- tocopherol (41.2-76.1 mg/kg), γ-tocopherol (20.5-27.5 mg/kg) and δ-tocopherol (6.5-14.2 mg/kg) and 24-methylcycloartenyl ferulate (140.2-183.1 mg/kg), cycloartenyl ferulate (65.5-103.6 mg/kg) and campesteryl ferulate (29.8-45.5 mg/kg) as the principal components. Overall, Basmati Pak, Basmati 198 and Basmati 2000 were found good nutritive varieties in respect of antioxidants poten- tial and valuable nutrients. In view of investigations of valuable phytochemicals and bioactives it is revealed that the rice has great potential for functional food and nutraceuticals applications. Efforts should be made to highlight the nutritive potential/quality of local aromatic rice varieties for enhanc- ing their commercialization at global level.