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Infield Superconducting Transport Properties of Magnetic Nanostructures-Cutl-1223 Composites

Thesis Info

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Author

Rehman, M. Waqee-Ur-

Supervisor

Muhammad Mumtaz

Program

PhD

Institute

International Islamic University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2016

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2801/1/Muhammad_Waqee_ur_Rehman_Qadri_Physics_2016_HSR_IIU_23.12.2016.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726453116

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(M) x -CuTl-1223; M = Ni, Co, CoFe 2 O 4 , Cr, Al 2 O 3 , nanoparticles-superconductor composites were synthesized by solid-state reaction (ceramic method) and their infield (magnetic) superconducting properties were investigated. Structural, morphological and compositional analysis of these composites were carried by using X-rays diffraction (XRD) analysis, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The infield transport measurements were carried out by resistance versus temperature (RT) measurements with small current ( ˷ 10 μA) by using four-probe technique with the help of physical properties measurement system (PPMS). Broadening in superconducting transition region was observed with increasing the external applied magnetic field (H) in all the samples, which was attributed to thermally activated flux flow (TAFF). Flux pinning strength was calculated by using TAFF model. The field dependent flux flow activation energy {U o (H)} of CuTl-1223 superconducting matrix was increased with addition of ferri-magnetic (CoFe 2 O 4 ) and antiferromagnetic (Cr) nanoparticles up to certain optimum level of concentration. The transition width (ΔT) of CuTl-1223 phase was decreased after addition of these nanoparticles. The enhancement in U o (H) and reduction in ΔT show improvement in flux pinning ability of CuTl- 1223 matrix with addition of CoFe 2 O 4 and Cr nanoparticles. The flux pinning strength of CuTl- 1223 phase was decreased with addition of ferromagnetic (Ni and Co) and non-magnetic (Al 2 O 3 ) nanoparticles. It was observed that U o (H) decreases and ΔT increases with the addition of these nanoparticles. The suppression in U o (H) with increasing magnetic field obeys the power law (U o = β H - a ) . The value of ‘a’ corresponds to the suppression rate of U o (H) with H. The decrease in ‘a’ with the addition of Cr, Co, and Al 2 O 3 nanoparticles showed that the decreasing rate of activation energy with increasing H is lowered with addition of these nanoparticles. Thus although the addition of Co and Al 2 O 3 in CuTl-1223 matrix decreases its flux pinning but their addition has lowered the suppression rate of U o (H) with H, which shows that the inclusion of these nanoparticles can make CuTl-1223 superconductor suitable for high field applications. In case of addition of CoFe 2 O 4 and Ni nanoparticles in CuTl-1223 superconductor, value of ‘a’ increases which indicates that lowering rate of activation energy increases with the rise in H. The transition width (ΔT) was increased with the rise in H, which shows TAFF takes place in the samples with small current. It was observed that broadening in ΔT with ‘H’ obeys a power law (ΔT = ΔT o + CH n ) where ΔT o is the transition width in absence of applied field.
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امجد علی غزنوی

امجد علی غزنوی
افسوس ہے کہ گزشتہ مہینے میں ہمارے ضلع اور شہر کے مشہور قومی کارکن، کامیاب وکیل اور اچھے شاعر جناب امجد علی غزنوی کا انتقال ہوگیا۔ انھیں اقبال سہیل اور مرزا احسان احمد سے مشورہ سخن کا شرف حاصل تھا۔ ان کے گھر پر اکثر نشستیں ہوتی تھیں اور انھوں نے بعض بڑے مشاعرے بھی کرائے۔ ان کا مجموعہ کلام ’’صہبائے خودی‘‘ بھی زیر کتابت تھا، تعلیمی کاموں سے بھی بڑی دلچسپی تھی۔ اپنے وطن محمدپور میں ایک دینی مدرسہ اور انٹر کالج ان کی یادگار ہے۔ شبلی کالج کی مجلس انتظامیہ کے ممبر اور ایک زمانے میں سینئر نائب صدر تھے۔ دارالمصنفین سے بھی تعلق تھا، یہاں برابر آتے تھے۔ مولانا مسعود علی ندوی کی سفارش پر کانگریس نے ۱۹۶۲؁ء میں انھیں ٹکٹ دیا تو صوبائی اسمبلی کے ممبر ہوئے۔ مگر اب سیاست کے گرے ہوئے معیار اور خود کانگریس کے رویے سے خوش نہیں رہتے تھے۔ بڑے باغ و بہار شخص تھے۔ دوسروں کی خدمت اور مصیبت زدہ لوگوں کی مدد کرکے خوش ہوتے تھے۔ قدرت نے انھیں دردمنددل اور بے چین طبیعت بخشی تھی۔ خود کہتے ہیں ؂
اک دل درد آشنا و اک نگاہِ حق نگر
اور کیا اس کے سوا امجدؔ سے دیوانے میں ہے
(ضیاء الدین اصلاحی، جنوری ۱۹۹۷ء)

 

اسوہ  حسنہ اورمغربی ذہن کے اشکالات.استشراقی فکرکے تناظرمیں تحقیقی و تنقیدی جائزہ

Western mind always remains muddled to fathom the Islamic belief “Prophethood” but it is grand reality that the West has contributed a lot in “Sirah Writing” from 17th to the present age. Although, in primary literature, Western scholars have delineated their abhorrence in this regard, without any research analysis. They usually used to twist the facts and misinterpret the text in attempt to sustain their assumption under their own perception. In the present age, literary change is seen in Western Writings that scholars have admired categorically the demonstrative Personality of Mohammad (PBUH) as well as they have praised his attributes as authoritative leader, Reformer, Peace maker etc. It will discuss the changes which were seen in Western writings about Sirah and analysis the causes and facts accordingly. It will also throw light on the Western assumption about Prophet Muhammad (PBUH); which has been prevailed in their writings before 19th even changed now. Islam is religion of Peace and Prophet of Islam has sent as” Blessing for All the Universe” from God Almighty so the question is what are the motives to bring forward theses western suppositions in this regard and at what extent it will affect? It will be discussed through comparative analysis among the Sirah books by Western Scholars Maxim Rodinson, Karen Armstrong and Michael Cook.

Modeling Spatiotemporal Regularity in Deformable Structures

A variety of dynamic objects, such as faces, bodies, and cloth, are represented in computer vision and computer graphics as a collection of moving spatial landmarks. A number of tasks are performed on this type of data such as character animation, motion editing, and nonrigid structure from motion. In theory, many of these tasks are highly under-constrained and the estimation algorithms exploit the natural regularity that exists as a cloud of points moves over time. In this thesis, we present compact and generalizable models of non- rigid objects by exploiting spatial and temporal regularities of time-varying point data. We demonstrate that several theoretically ill-posed tasks can be made well-posed with the help of these models. Our first contribution is to propose and demonstrate the effectiveness of the linear trajectory model for representing time-varying point clouds. Traditionally, a linear shape model has been used to represent time-varying point data; the 3D shape of a nonrigid object is modeled as a linear combination of a small number of basis shapes. In contrast, we represent point trajectories as a linear combination of basis trajectories. We show that the linear trajectory and the linear shape models are dual to each other and have equal representation power. In contrast to the shape basis, however, we demonstrate that the trajectory basis can be predefined by exploiting the inherent smoothness of trajectories. In fact, we show that the Discrete Cosine Transform (DCT) is a good choice for a predefined basis and empirically demonstrate its compactness by showing that it approaches Principal Component Analysis (PCA) for natural motions. This linear trajectory model is applied to the problem of nonrigid structure from motion. Analogous to the formulation under the shape model, the estimation of nonrigid struc- ture from motion under the trajectory model results in an optimization problem based on orthonormality constraints. Prior work asserted that structure recovery through orthonor- mality constraints alone is inherently ambiguous and cannot result in a unique solution. This assertion was accepted as a conventional wisdom and was the justification of several remedial heuristics in literature. In contrast, we prove that orthonormality constraints are, in fact, sufficient to recover the 3D structure in both the linear trajectory and the shape models. Moreover, we show that the primary advantage of the trajectory model over the shape model in nonrigid structure from motion is the possibility of predefining the basis.This results in a significant reduction in unknowns and corresponding stability in estima- tion. We demonstrate significant improvement in reconstruction results over the state of the art. After demonstrating the effectiveness of the linear trajectory model over linear shape model in nonrigid structure from motion, we also show how both the models can be synergisti- cally combined. We present the bilinear spatiotemporal basis as a model to simultaneously exploit spatial and temporal regularities, while maintaining the ability to generalize well to new sequences. The model can be interpreted as representing the data as a linear com- bination of spatiotemporal sequences consisting of shape modes oscillating over time at key frequencies. We apply the model to natural spatiotemporal phenomena, including face, body, and cloth motion data, and demonstrate its effectiveness in terms of compaction, gen- eralization ability, predictive precision, and efficiency against existing models. We demon- strate the application of the model in motion capture clean-up. We present an expectation- maximization algorithm for motion capture labeling, gap-filling, and denoising. The solu- tion provides drastic reduction in the clean-up time in comparison to the current industry standards.