Solar wind has no longer remain a mystery now as in-situ measurements by different satellites have provided us a deep picture of solar terrestrial plasma. However, it still contains some unexplained marvels which need further theoretical as well as observational investigations. Qne of these phenomena is the damping or growth of different kinds of waves in the solar wind and magnetosphere. On a micro scale, waves can grow as a result of different kinds of instabilities. In this dissertation, those instabilities are investigated which are generated by the departure of particle distribution function from thermal equilibrium. Such type of instabilities are termed as micro-instabilities and are dependent upon the shape of the distribution function. Different sources such as pressure or temperature anisotropies, relative drift or counterstreaming particles, temperature gradients, etc. can ignite micro-instabilities. In this dissertation we consider counter-streaming plasma and temperature anisotropies as the source of micro-instabilities. Observations of solar wind particle velocity distribution functions generally contain nonthermal features which result in departure from Maxwellian distribution. These nonthermal features of the distribution functions are well characterized by relatively cool dense ''core'', the energetic suprathermal tails ''halo'' and the field aligned beam ''strahl''. It is found that cool dense population is composed of 95% of the total population and the rest is composed of halo and strahl population. In-situ observations reveal that near the Sun the energetic strahl and halo electron populations contain a drift in anti-sunward direction while core contains a drift generally towards the Sun. Such a drift among plasma species could generate Buneman or heat flux type of instabilities in solar wind frame depending upon the type of streaming. If core and halo electrons possess a counter relative drift in solar wind proton rest frame, it could excites magnetosonic, Alfven or whistler heat flux instabilities. All of these instabilities are observed near 1 AU and widely studied in literature. However, whistler heat flux instability is reported to be the most unstable heat flux mode for realistic solar wind conditions. Though, in this dissertation it is highlighted that it is somewhat improper to call this left-handed evolved heat flux instability as right-handed whistler heat flux instability. The electron heat flux instability investigated here, basically evolves out as a primary left-hand heat flux mode, which result due to the interaction of Dopplerix I P age upshifted whistler and left-handed proton cyclotron mode. However, for relatively smaller magnitude of counter-streaming drifts, only right-handed whistler heat flux instability takes place as reported in literature. Furthermore, our investigation revealed electron heat flux instability and electron firehose instability to be highly reminiscent though there sources offree energy are different. Electron heat flux instability is caused by counter-streaming of the ''Plasma and electron firehose instability by excessive temperature parallel to the ambient magnetic field. Since solar wind plasma is anisotropic in nature, these temperature anisotropies, being the source of microinstabilities, can excite both electron cyclotron and proton cyclotron type of instabilities. Of which here a comparison between electron heat flux instability and electromagnetic electron cyclotron (EMEC) wave is presented concomitantly. This comparison illustrated different polarizations of these two modes and confirms our assertion that heat flux instability is not right-handed. Also heat flux instability being left-handed mode and electromagnetic electron cyclotron being right-handed mode exhibit different characteristics when investigated concomitantly for relative streaming and temperature anisotropies. Alfven instability caused by the proton temperature anisotropies has frequently been reported in outer corona of the Sun, solar wind and terrestrial magnetosheath. In this dissertation, we studied Alfvenic fluctuations in the solar wind by analyzing the CLUSTER data. A linear theory is established based on the (r, q) distribution function to investigated the growth rate of Alfven waves in presence of electron and ion anisotropies as well as electron to ion temperature ratios. We found that growth rate also affected by electron to ion temperature ration which was not considered previously in literature. We also found that threshold instability curve sets in good agreement with instability-threshold-histogram plotted for observed temperature anisotropies versus beta.
سکولاں وچ گرمی دیاں چھٹیاں سن، عادل اپنی دادی نوں ملن ملتان آیا ہویا سی۔ اوہ چھٹیاں وچ اپنی دادی کول ضرور آندا سی۔ ایس لئی کہ اوس دی دادی اوس نوںبہت پیار کر دے تے کئی شیواں لے کے دیندی سی۔ اک وار دادی نے اوس نوں آکھیا کہ میں بازار توں کجھ گھر دیاں شیواں خریدنیاں نیں۔ توں میرے نال بازار چل۔ عادل تیار ہو گیا۔ دونویں اک رکشے وچ بیٹھے تے بازار آ گئے۔
بازار وچ آ کے پہلاں اوہناں کجھ چیزاں دیاں قیمتاں پچھیاں تے فیر اک وڈے سٹور اندر چلے گئے۔ ایس سٹور تے پھل، سبزیاں، بسکٹ، مٹھائی کپڑے، بالاں دے کھڈوانے تے ضرورت دی ہر شے موجود سی۔ دادی خریداری وچ مصروف ہو گئی تے عادل اوتھے موجود شیواں نوں ویکھن لگ پیا۔ مٹھائی والے کائونٹر اگوں لنگھدے ہویاں۔ اوس دا مٹھائی کھاون نوں دل کیتا۔ اوس ادھر اُدھر ویکھیا۔ جدوں اوس نوں یقین ہو گیا کہ اوس نوں کوئی نئیں ویکھ رہیا تاں اوس اک گلاب جامن چک کے کھا لیا۔ جدوں اوس دی دادی مٹھائی والے کائونٹر کولوں لنگھی تاں عادل اوتھے ای کھڑا منہ ہلا رہیا سی تے شیرہ اوس دے منہ اتے لگا ہویا سی۔ اوس دی دادی فوراً اوس سٹور توں باہر لے کے آئی تے پچھیا کہ توں کیہ کھاہدا اے؟ اوس جواب دتا کجھ وی نئیں۔ دادی نے پچھیا کیہ توں مٹھائی کھاہدی اے؟ اوس جواب دتا جی دادی اماں، دادی اماں نے پچھیا کیہ ایس سٹور توں چک کے کھاہدی اے؟ اوس آکھیا جی ہاں۔ دادی نے پچھیا توں سٹور والے دی اجازت توں بغیر کھاہدی اے؟ اوس آکھیا جی ہاں، دادی نے آکھیا جا کے سٹور والے کولوں معافی منگ تے نالے پیسے ادا کر۔ عادل کیہندا اے کہ جے میں اوس نوں...
Journalism in Pakistan has passed through successive phases of trials and tribulations. The crises journalism had to undergo since independence had their origin both in the state policies as well as the authoritarianism embedded in the society. The book under review does not claim to divulge into the societal challenges which have emerged more visibly in the last three or four decades, especially, in the context of the spread of religious extremism and ethnic and other types of militancy in the society. Studies need to be done on these aspects as well as the external factors that have had impact on the growth and the content of media. The latter has come in the garb of globalization that has greatly affected the local environment and has come to strongly affect, if not directly dictate, what the media should encompass and present. Leaving the societal and global aspects aside, the role of the state and the successive governments has a lot to offer to be written about by way of what the media has endured in the last seventy plus years. It doesn’t need too much of pondering to conclude that the major pressures over media have come from the governments who, by and large, had been quite at unease with independent flow of information, and criticism of their policies. And, unfortunately, this process had begun right after Independence when newspapers’ and periodicals’ independent voice was tried to be silenced, and they were pressurized to toe the official line with respect to domestic and foreign policies. Pakistan’s independent journey, unfortunately, began with the imposition of black laws which prohibited dissent and curtailed freedom of expression in the strongest possible manner.
This work presented in the thesis pertains to the design of a pilot plant based on new blasting explosives developed from decanted Trinitrotoluene (TNT). Disposal of life-expired and unwanted munitions is a great challenge across the globe. In the past, these unserviceable explosives were disposed of through conventional disposal techniques such as Open Burning/ Open Detonation (OB/OD), sea dumping, underground demolition, incineration and biological degradation. Production of poisonous and toxic gases such as NOx, COx, etc. during these disposal techniques have always been a great concern for Environmental Protection Agency (EPA). Besides, labour cost for the preparation of disposal pits, fuel requirement for shifting of explosives to munition disposal sites and use of large quantities of serviceable explosives during disposal of these unwanted munitions makes these techniques most uneconomical, unsafe and unfriendly for the environment. In order to curtail all these practices, decanting of explosives through decanting plant were carried out for different munitions. All decanted explosives, particularly decanted TNT, were disposed of further through open air burning. In the present research work, efforts have been made to reutilize the decanted TNT. For this purpose, various ingredients such as oxidizers, stabilizers and additional fuels have been added to the decanted TNT to convert it into viable blasting explosive compositions. Laboratory scale experiments using decanted TNT and other ingredients such as calcium ammonium nitrate (CaAN), commercial grade wax and calcium carbonate (CaCO3) have been carried out to make different blasting compositions. All the newly formulated compositions were characterized through different analytical techniques such as Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Thermogravimetry/ Differential Thermal Analysis (TG/DTA) and Fourier Transform Infrared (FTIR) to study their morphological and thermal cum kinetic properties. Simultaneously, Horowitz and Metzger method is used for calculation of activation energy (Ea) and enthalpy of different samples. Once all compositions were certified for their future use, velocities of detonation (VOD) measurements were conducted. Besides, stability tests, the density of all these compositions were also measured. In order to translate the laboratory scale compositions into useable blasting explosives, a pilot scale plant has been designed using PTC-Creo Parametric 3D modeling software. Similarly, simulation of the design was carried out through Aspen Plus® V8.4 simulation software. Based on the successful simulation and design results, a state-of-the-art, safe, feasible and environment friendly semi-automatic pilot scale plant has been fabricated and installed for the conversion of decanted explosive into blasting explosives for civil and military applications. Main components of the plant include double jacketed mixing drums, brass-made mashing roller, 5 Horse Power (HP) motor, vertical gear box and fume discharging unit having explosives production capacity of about 10kg/ hour per batch. All the safety parameters required during manufacture, filling and formulation of explosives have been ensured to avoid any untoward situation. Functional test of this plant was performed using dummy explosive materials having almost similar compositions. Subsequently, blasting explosive samples were produced utilizing decanted TNT and other suitable ingredients. To ascertain their performance, VOD tests of all newly formulated blasting explosives have been performed. It is worth mentioning that the resultant VOD of all the samples fall between 2600-4400 m/s which makes it the most suitable product for use in blasting applications such as mining, quarrying, underwater blasting, etc. In a nutshell, the present research work not only provides an opportunity for riskfree reutilization of decanted TNT where new products are easily manufactured, cheap in cost and safe in handling; but EPA concerns regarding emissions of toxic gases into the atmosphere are also amicably addressed through reutilization of unwanted TNT that will ultimately enhance Carbon Credit Ratings of Pakistan around the globe.