Dependability is an umbrella concept that subsumes many key properties about a system, including reliability, maintainability, safety, availability, con- dentiality, and integrity. Various dependability modeling techniques have been developed to e ectively capture the failure characteristics of systems over time. Traditionally, dependability models are analyzed using paperand- pencil proof methods and computer based simulation tools but their results cannot be trusted due to their inherent inaccuracy limitations. To overcome these limitations, we propose to leverage upon the recent developments in probabilistic analysis support in higher-order-logic theorem proving to conduct accurate and rigorous dependability analysis. This thesis provides a semantic language embedding of the dependability concept that relies on a theory for probabilistic reasoning to develop a framework for formal dependability analysis within the sound environment of higher-order-logic theorem proving. In this thesis, we mainly focus on the formalization of two widely used dependability modeling techniques: (i) Reliability Block Diagrams - a graphical technique used to determine the reliability of overall system by utilizing the failure characteristics of individual system components; and (ii) Fault Trees - used for graphically analyzing the conditions and the factors causing an undesired top event, i.e., a critical event, which can cause the whole system iv v failure upon its occurrence. In particular, we present a RBD and FT-based formal dependability analysis framework that has the ability to accurately and rigorously determine the formal reliability, failure, availability and un- availability of safety-critical systems with arbitrary number of components. To illustrate the practical e ectiveness of our proposed infrastructure, we present the formal dependability analysis of several real-world safety-critical systems, including smart grids, WSN data transport protocols, satellite solar arrays, virtual data centers, oil and gas pipeline systems and an air tra c management system using the HOL4 theorem prover.
ام المومنین حضرت زینب ؓ بنت خزیمہ ان کا پہلا نکاح حضرت عبیدہ ؓ بن حارث بن عبدالمطلب سے ہوا ۔ ان کی وفات کے بعد جہم بن عمرو سے نکاح ہوا اور وہ بھی غزوہ بدر میں کام آئے تب تیسرا نکاح عبداللہ ابن جحش ؓسے کیا انہوں نے بھی غزوہ احد میں جام شہادت نوش کیا ۔ اس طرح یکے بعد دیگرے حضرت زینب ؓ بیوگی کے صدمہ سے دو چار ہوئیں لیکن غم گسار آقا آنحضرت ﷺ نے اپنے حرم میں انہیں داخل فرمایا ۔ قدرت کو یہی منظور تھا کہ آپ ام المومنینؓ کے اعزاز سے بہرہ ور ہوں اور آپ ﷺ کے ساتھ دور کی رفاقت میسر نہ ہو ، ایسا ہی ہوا کہ صرف چند ماہ بعد سیدہ زینب بنت خزیمہ ، جو ام المساکین کی کنیت سے معروف تھیں ، کا انتقال ہو گیا ۔ وفات کے وقت ان کی عمر مبارک تیس برس تھی ۔ صہیب ؓ آہن گر تھے ۔ قریش نے روک دیا کہ مدینہ ہجرت نہ کریں ۔ سامان باندھ کر مدینہ منورہ کو چلے تو قریش نے کہا ’’ جب تم یہاں آئے تھے تو فقیر تھے ، محتاج تھے ، یہاں رہ کر مالدار اور غنی ہو گئے ہو ، اور اب تم چاہتے ہو کہ وہ سب کچھ جو تم نے یہا ں کمایا ہے وہ ساتھ لے کر مدینہ چلے جائو ۔۔۔ واللہ ! یہ تو ہم کبھی نہ ہونے دیں گے ‘‘۔ حضرت صہیب ؓ نے کہا ’’ اگر میں یہ سارا کچھ تمہارے لیے چھوڑ دوں تو کیا مجھے جانے دو گے ‘‘؟ مشرکین بولے ’’ہاں ! پھر تم آزاد ہو ۔ ‘‘ صہیب ؓ نے بغیر سوچے اور بغیر کسی جھجھک کے اپنا سارا سامان کفار کے حوالے کیا اور خالی ہاتھ مدینہ روانہ ہو گئے ۔ جب...
Qazi Ayaz Malki is a famous scholar of the west. He has written books on various sciences and arts. His famous book is Al-Shafa'ah betareef e Huqooq El Mustafa. This book has given him eternal life because of this book he has reached the highest of fame even today. The rights and particularities of the Prophet (SAW) are mentioned in this book. The topic under consideration is an introduction to Qazi Ayaz Malki's life situation and his book Al-Shafa'ah Al-Shareef Huqooq Al Mustafa. And this book talks about the objections which are been raised and their detailed answers
In order to produce good financial results and improve operational performance, a firm should effectively and efficiently manage its working capital. Working capital policies and practices vary from firm to firm which leads to variation in profitability. A difference in working capital practices is observed on the basis of size and location. Review of existing literature indicates that this variation in working capital management practices among various categories of firms such as small, medium, large, domestic and multinationals has not yet been adequately researched, particularly in developing countries like Pakistan. The study uses secondary data of 153 listed firms on Pakistan Stock Exchange for 10 years (2004-2013). These firms are categorized on the basis of size viz. small, medium and large; as well as location such as domestic and multinationals. R-square shows that highest explanatory power of the independent and control variables included in the model based on market to book ratio occur in multinational firms where dependent variable is explained to the extent of 41% whereas based on return on assets it is 26% in medium firms. Results show that working capital policy significantly affects firms’ performance. Multinomial logistic regression model was used to identify factors significantly affecting WC policy. Logistic regression results show that ROA and MC are the variables determining the WC policy of firms significant at 5% and 1% respectively. Overall, correct predictions for the study employing logistic regression model work out to be 71.9% showing fitness of the model used for analysis.