پتّھر
بیٹھا تھا مَیں کمرے اندر
غور سے میں نے جب دیکھا تھا
آگے ، پیچھے ، اوپر ، نیچے
پتّھر ، پتھر ، پتھر ، پتھر
چیزیں ساری پتھر کی تھیں
چھت دیواریں پتھر کی تھیں
کمرا سارا پتھر کا تھا
صحن میں نکلا میں نے دیکھا
گھر بھی سارا پتھر کا تھا
اک تنہائی گونج رہی تھی
جب میں گھر سے باہر نکلا
روڈ بھی سارا پتھر کا تھا
لوگ بھی سارے پتھر کے تھے
سوچ بھی ساری پتھر کی تھی
شہر ہی سارا پتھر کا تھا
رات ہوئی تو میں نے دیکھا
چاند فلک پر پتھر کا تھا
تارے سارے پتھر کے تھے
چیخ جو ماری پتھر گونجے
چیخ بھی ساری پتھر کی تھی
لوٹ کے آیا خود کو دیکھا
اور پھر میں بھی پتھر کا تھا
Pendidikan yang semula dengan metode tatap muka di lembaga pendidikan, kini diubah menjadi pembelajaran daring/online dan dilaksanakan dari rumah masing-masing untuk mencegah dan menanggulangi penyebaran virus COVID-19 ini. Kebijakan tersebut berlaku bagi semua jenjang pendidikan baik dari tingkat PAUD hingga tingkat perguruan tinggi. Hal tersebut menimbulkan banyak problematika khususnya pelaksanaan pembelajaran bagi anak usia dini. Pembelajaran dengan menggunakan sistem daring ataupun sistem online ini masih mengalami banyak problematika dalam penerapannya, karena anak tidak dapat belajar sendiri tanpa pendampingan dari orang tua. Dalam mendorong kualitas pembelajaran pada Anak Usia Dini perlu kerjasama dan dukungan orang tua. Orang tua menjadi salah satu pihak yang bertanggung jawab dalam keberlangsungan pendidikan anak usia dini di masa covid-19. Pengasuhan positif, penyediaan lingkungan belajar yang memadai, dan sumber belajar yang relevan akan sangat membantu anak usia dini dalam menjalani masa transisi menuju era new normal. Oleh karena itu, komunikasi antara guru dan orang tua harus berjalan dengan baik. Kebijakan pemerintah tentang belajar dari rumah tidak serta merta membuat guru melepaskan tugasnya dalam memberikan pendidikan kepada anak usia dini. Justru hal tersebut menuntut guru untuk meningkatkan kompetensinya dalam melakukan pembelajaran jarak jauh dan tetap menilai perkembangan anak berdasarkan laporan kegiatan dari para orang tua.
To propose e cient and better designs for small swimming and ying unmanned vehicles, understanding of the unsteady mechanisms to generate lift and thrust forces at low Reynolds numbers is of key importance. Fluid owing over these vehicles interact nonlinearly with the structure and carries great complexities. Recently, due to interest in biomimicking ying (micro-air vehicles) and swimming robots (underwater vehicles), industry has shown keen interest in production of these vehicles. To design e ective control of these vehicles, thorough understanding of its unsteady aerodynamics and underlying phenomena is required. In this study, we focus upon coupling the numerical simulations with the tools of nonlinear dynamics. We decompose this whole study into two parts; aerodynamics and hydrodynamics. In therst part, we investigate the bifurcations occurring in the ows over oscillating airfoils at low Reynolds numbers. Investigation of mechanism responsible for the generation of unsteady forces pose challenges due to wide spectrum of parameters that are involved in its dynamics. Both experimental and currently available numerical techniques require costly resources in terms of time and money. Considering this fact, we also develop nonlinear reduced-order models for unsteady aerodynamic forces produced by plunging, pitching, and apping airfoils. Observing similarity in the character of unsteady forces generated by pitching, and plunging airfoils, we propose an equivalence criteria to obtain the aerodynamic forces of same magnitude or order. We also demonstrate that de ection of the wake for large Strouhal numbers is a result of strong quadratic nonlinearity. With the lessons learnt from the nonlinear analysis/interaction of apping airfoils, we investigate the hydrodynamics ofsh swimming in the second part of this dissertation. We consider a singlesh and twosh in tandem performing traveling-wave like motion, known as undulation. In case of tandem con guration, we numerically simulate the ow while both sh undulate asynchronously. We quantify the drafting and inverse-drafting e ects using time-averaged drag coe cients. We also explain physical mechanisms which are responsible for hydrodynamic advantage/disadvantage to upstream and downstreamsh. To further enhance our understanding related to the instability mechanisms in the wakes of undulating bodies, we compute the symmetry/asymmetry of parent and combined modes. We apply the symmetry principles, already established for drag-producing wakes of blubodies, to the thrust-producing wakes of undulatingsh. We conclude that thrust producing wakes also follow the same symmetry principles. This research addresses the coupling of techniques/tools of nonlinear mechanics with computational uid dynamics to explore important features of complex ows around oscillating and undualating bodies.