حاصل تحقیق
زبان اللہ تعالیٰ کی عطا کردہ نعمتوں میں سب سے بڑی اور عظیم نعمت ہے۔ اس پر سنجیدگی سے غورکرنے کا سلسلہ روزِ اول سے ہی جاری ہے۔ قبل مسیح کےمفکروں اور دانش وروں نے بھی اس پر بہت غور وخوض کیا اور اس کے متعلق مختلف نظریات قائم کیے، اس سلسلے میں مختلف کتب موجود ہیں جو زبان کے متعلق قبل مسیح کے نظریات سے بھری پڑی ہیں۔
اس کے بعد آنے والے مختلف مفکرین نے اس پر تحقیقی کام جاری رکھا۔ اور زبان کے متعلق اپنے نظریات پیش کرتے رہے۔ ان نظریات سے مختلف ماہرین لسانیات نے لسانیات کےمختلف شعبے تخلیق کیے اور ہر شعبے میں خاطر خواہ کام کیا۔
انیسویں صدی میں لسانیات پر باقاعدہ تحقیقی ادارے بننے شروع ہوئے،مغرب نے اس سلسلے میں بہت کام کیا، لیکن یہ بات عیاں ہے کہ بیسویں صدی میں ادب پر جتنا کام ہوا وہ گزشتہ ایک صدی تک نہ ہو سکا، بلاشبہ اس صدی کو ادب کی صدی کہا جاتا ہے اس میں باقی شعبوں کے ساتھ ساتھ لسانیات جیسے اہم مضمون پر بھی بہت زیادہ خامہ فرسائی کی گئی۔
زبان میں لسانیات کے موضوع کے حوالے سے اگر دیکھا جائے تو یہ مختلف عناوین اور اس کےمسائل ومباحث کو سمیٹے ہوئےہے۔ جہاں اس کا تعلق نطق انسانی سے ہے وہاں زبان کے قواعد اور لغتیات پر بھی بحث کرتی ہے۔ اگر لسانیات کی صرف نطق انسانی کے حوالے سے بات کی جائے تو یہ بات عیاں ہے کہ لسانیات کا کسی مخصوص گروہِ انسانی سے تعلق نہیں بلکہ یہ دنیا کی تمام زبانوں کے مسائل کو زیر بحث لاتی ہے۔ مختلف ماہرین لسانیات نے اس کی تعریف مختلف حوالوں سے کی ہے۔ ان میں چند ایک درج ذیل ہیں:
’’زبان کا سائنسی مطالعہ لسانیات کہلاتا ہے۔
Islamic Shariah provides a complete code of life, as man can take guidance from Shariah, regarding each and every aspect of his life. Commerce plays a pivot role in human life which has been mentioned time and again in Quran and Hadith. According to one Tradition, Allah has affixed and set 10 parts of sustenance and in these ten parts, nine are in Trade. In Shariah the luminary Islamic scholars and jurists have deputed peculiar and separate subjects with different titles regarding Trade, the most famous and acknowledged are "Kitab-ul-Mutajir" and "Kitab-ul-Biyou". Islam elevates and upgrades those who toil and labour hard, among them the Labourer has prominent state and he is above all among them. According to the sacred utterance of Hazrat Muhammad SAWW: "You should pay the labourer his wages before his sweat dries away”. In the present era, no one can deny this fact that this world has become a global village, therefore new ways and system of commercial are in vogue and being applied besides some traditional ways. Such as Banking System, E-Purchasing, Online shopping and some other modes and means. In these traditional, latest and new trading systems, usually the labourers are being exploited because they are given less poor wages than their rigorous toilsome labour. However in the under discussion article the labourer rights and their utmost implementation in the trade of present era would be reviewed and analyzed in the light of Seerat-ulNabi SAWW.
Computational fluid dynamics (CFD) has become a powerful tool for solving complex fluid flow problems in the last few decades. The relation between the flow regime transformation and its corresponding hydrodynamics forces on the staggered cylinders has not been studied at low Reynolds number (Re), both experimentally and numerically. In order to do so, numerical investigations are conducted to study the unsteady flow past square cylinders arranged in staggered configurations. Six distinct staggered geometries are constructed for which simulations are carried out by using two dimensional single relaxation time lattice Boltzmann method (SRT-LBM). The combined effect of Re and separation ratio (g*) on the flow physics and hydrodynamics forces is systematically studied. For this study, physical parameters of practical importance are chosen in the range of 20 ≤ Re ≤ 160 and 0 ≤ g* ≤ 7. The SRT-LBM was validated by comparing the unsteady flow around an isolated cylinder and two cylinders with available experimental and numerical data. Results are presented in the form of instantaneous vorticity contour visualization, time-histories of drag and lift forces, power spectra of lift signals and hydrodynamic forces. For all chosen geometries critical spacing ratio and Reynolds number are identified. It is observed that with increase in spacing ratios between the cylinders the critical Reynolds number for the onset of vortex shedding phenomena also increases. Different flow regimes are observed for different staggered geometries. Chaotic flow is one of the common flow regime. The transformation of the flow occurs due to the interaction between primary and secondary frequencies; the latter frequency strongly depends on the spacing ratio between cylinders. The effect of jet flows on the wake structure mechanism (shed vortices) behind the cylinders is studied in detail. The results show that both Re and g* have a significant effect on the hydrodynamic forces. The flow regime maps for varying Re and g* are proposed for all considered problems. All these results, most of which have been obtained for the very first time, are of fundamental significance in engineering applications.