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Investigation of Envelope Solitons and Modulational Instability in Multicomponent Plasmas

Thesis Info

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Author

Naseem Akhtar

Program

PhD

Institute

Pakistan Institute of Engineering and Applied Sciences

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/12178/1/Naseem%20Akhtar_Phy_2019_PIEAS_PRR.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726502863

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The study of nonlinear wave propagation in plasmas is an emerging area of research to understand of energy or particle transport phenomenon in space, astrophysical and laboratory plasmas. In this work, modulational instability and envelope solitons excitations of electrostatic plasma waves in dilute plasmas are studied in the presence and absence of magnetic field in multicomponent plasmas. Envelope solitons are excited in a plasma medium when wave dispersion due to group velocity is balanced with nonlinearity of the medium. The excitation, propagation, stability of envelope modulated soliton structures and freak/rogue waves in different multicomponent plasmas are discussed. Plasma models comprised of electron-positron-ion, electronion- dust are considered with and without magnetic field for static and dynamic dust charged particles. Both positive and negative polarities of static charged dust particles are taken and studied their effects on propagation characteristics of nonlinear structures. The thermal (Maxwellian distribution) as well as nonthermal (kappa distributions function) for light mass plasmas species such as electrons and positrons, are considered to describe the excitations and stability of envelope solitons in space plasmas. The well known Krylov-Bogoliubov-Mitropolsky (KBM) method is applied to derive nonlinear Schrödinger equation (NLSE) for amplitude modulation of the plasma waves. This method is useful for explaining the long time behavior of the solution which consists of varying the wave amplitude so slowly that no secular term arises in the solution. The analytical and numerical investigations of NLSE are presented for different plasmas systems. The modulational instability and its growth rate are also discussed in detail. The stable and unstable regions for Ion acoustic wave (IAW), Dust-ion acoustic wave (DIAW), Dust-ion cyclotron wave (DICW), Dust acoustic wave (DAW) and Dust cyclotron wave (DCW) are investigated for the formation of dark or bright envelope solitons. The role of different plasma parameters like, plasmas density, temperature, spectral index, dust polarity, magnetic field and propagation angle on the stability of nonlinear envelope soliton structures are presented. The observations and propagation of fundamental rogue waves (RWs) and super RWs in space plasmas and in laboratory experiments are also pointed out.
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ڈاکٹر ضیاء الدین

ڈاکٹر ضیاء الدین مرحوم
افسوس ہے کہ گزشتہ ۲۴؍ دسمبر ۱۹۴۰؁ء کو ڈاکٹر سر ضیاء الدین مرحوم نے بعارضہ فالج لندن میں انتقال کیا، مرحوم اپنے علمی کمال میں ہندوستان کے مشاہیر میں تھے، وہ تعلیم کے ماہر اور ریاضیات کے ممتاز فاضل تھے، انھوں نے اپنی تعلیم کے زمانہ میں ان فنون میں ہندوستان اور یورپ کی درسگاہوں میں جو امتیازات حاصل کئے، وہ اس دور میں کم ہندوستانیوں کو حاصل ہوئے تھے، چند دنوں جامعہ ازہر میں بھی رہے تھے، اس لئے عربی سے بھی کچھ واقف تھے، ان کی پوری زندگی علم و تعلیم کی خدمت میں گزری اور وہ نصف صدی سے زیادہ کسی نہ کسی حیثیت سے مدرسۃ العلوم اور اس کے بعد مسلم یونیورسٹی سے وابستہ رہے، کئی مرتبہ وائس چانسلر ہوئے، ابھی تھوڑے دن ہوئے کہ اس عہدہ سے سبکدوش ہوئے تھے، برسوں مجلس مقننہ کے ممبر رہے، مالیات میں ان کی رائے اور مشوروں کو خاص اہمیت حاصل تھی، ان کو اس زمانہ کے بڑے سے بڑے اعزاز حاصل ہوئے، جن سے یونیورسٹی کو بھی فوائد پہنچے اور ان کے دور میں اس کو بڑی ترقی ہوئی، ان کا آخری کارنامہ میڈیکل کالج کا قیام ہے، چند مہینے ہوئے جدید تعلیمی نظام کے مطالعہ کے لئے یورپ اور امریکہ گئے تھے، کہ لندن میں پیام اجل آپہنچا۔
مرحوم اس دور کی پیداوار تھے، جب مسلمانوں پر مغربی تمدن مسلط تھا، اور اس کا سب سے بڑا مرکز علی گڑھ تھا، لیکن انھوں نے اس کا بہت کم اثر قبول کیا، اب تو ضعیفی کی عمر تھی، وہ ہر زمانہ میں نہ صرف عقیدے بلکہ ظاہری وضع قطع میں بھی مسلمان رہے، ان کی زندگی بڑی سادہ اور بے تکلف تھی، ان کی سادگی میں ایک صاحبِ کمال کی شانِ بے نیازی پائی جاتی تھی، شخصی طور پر بھی ان...

Admissibility of a Video As Evidence in a Court: its Presentation and Probative Value

To general public, all videos are perceived to be true, but they may not have probative value in the Court of law. The undertaken article analyzes the admissibility and probative value of a video presented as evidence before a court in the Criminal Justice System of Pakistan (CJSP). It analyzes the relevant law and diagnoses the problems with the video evidence through the lens of the judgments of Superior Courts. The court of law objectively ascertains that a video presented as evidentiary means bears significant relevance to the fact in question. It must be admissible under the law, and it must be proved to be genuine. To fill up the gap between a “Video” and a “Video Evidence”, there is a process, which is known as video authentication. It determines that the video contents are genuine, authentic, credible, unaltered, untampered and unfabricated. The study discusses various modes of video authentication. Precedents set by superior courts of Pakistan show that convictions have been made once the courts are satisfied with the credibility of video evidence. In the court of law, video evidence is normally presented after the completion of prosecution evidence. The video is played in court and is watched by the presence. But the researcher establishes that such process does not have legal justification. The article suggests that it would be legal and proper for the prosecution to produce the video evidence through the witness, during his evidence, who is either victim, witness, recorded and/or copied the video directly from original source such as C.C.T.V system and that witness would be subjected to cross examination.

Tectonic Evolution of the Margala Hills and a Part of the South Eastern Hazara Ranges, Pakistan

The Margala Hills and Hazara Ranges are the south-western continuation of the HazaraKashmir Syntaxis in North Pakistan, constituting an east-northeast trending fold-thrust belt of Jurassic to Eocene platform sediments, partially overlying Late Precambrian basement. The current field investigations have revealed that at least three macro-scale fold-thrust nappes, which are structurally linked to a regional basal detachment located at base-Hazara Slate, fabricate the structural grain of the Margala Hills and southeast Hazara Ranges. From north to south these nappes include the Hazara fold-thrust nappe which is exposed along Hazara Thrust. Below the Hazara nappe lays the Garamthun nappe which is exposed at surface along Garamthun Fault. Southeast of the Garamthun Fault the hanging wall sequence of the Main Boundary Thrust constitutes the third fold-thrust nappe of the area and constitute the foothills of Margala Hills. All these fold-thrust nappes are characterised by east-northeast trending major anticlinal folds detached at the level of Jurassic rocks. The stratigraphic set up of these fold-thrust nappes implies a gradual south younging of structuration of the study area. The lithostratigraphic offset along the mapped faults is very little and does not support large scale horizontal movements with the thrust faulting alone. The large scale fold-thrust belt allochthony is shared by fold nappe mechanism which is also believed to be responsible for the thickening of the sedimentary pile. Mesoscopic and macroscopic folds data indicate the presence of at least three distinct lines of folding including northeast-southwest followed by southeast and north-south trends. The northwest-southeast compression is the prominent grain of the southeast Hazara and Margala Hills. Mesoscopic fault planes can be categorised into three distinct sets. The most prominent is the top to the southeast followed by top to the west-northwest and northeast. The top the southeast set is consistent with the movement direction on the macroscopic scale faults (Hazara Thrust, Garamthun Fault and Main Boundary Thrust) and the pitch data is suggestive of a dominant thrust slip motion in addition to left lateral strike slip adjustments. The second set that is the top to the west-northwest can be considered as the back thrusting phenomenon associated with the top to the southeast major displacement. The third set and a few other less prominent fault planes are generally oriented discordant to set one and two and indicate the transpressional related adjustments of the region. Most of dips in the hanging vii wall of Main Boundary Thrust are found to be overturned to the northwest and the axial planes of the folds mostly dip southeast. This back folding is most prominent and consistent along the hanging wall of Main Boundary Thrust and gradually defuse in the northwest direction. The synthesis of the structural data indicate that in the whole Miocene southward directed major shortening created a southwards propagating, flat-ramp thrust fault, cutting up section. This basal thrust carried the Margala Hills Mesozoic and part of its Murree cover towards the south above thicker Murree molasse and underlying Northern Potwar Deformed Zone Mesozoic nappes. Increased shortening took place by tight folding of the hanging wall. This could be the main reason of folds found in the Margala Hills. Late (?) Pliocene major, crustal or lithospheric scale folding created the Hazara Kashmir Syntaxis and created north-south to northeast-southwest axis folds in the Margala Hills. This event is responsible in the first instance for the east or west verging structures in the whole area, for the northwards or northwestwards overturned folds of the Margala Hills; and for the major crustal thickening and subsequent very important uplift of the whole area. The same event could have created strike slip faulting. Repeated south verging thrusting in Quaternary resulted in the southwards movement of the Salt Range above Pleistocene sediments, and flat, mostly south verging thrust faults cutting the older structures. This last event may have generated deeper ramps in the Northern Potwar Deformed Zone and may have formed folds and uplifts in the Northern Potwar deformed Zone and beneath the frontal part of Margala Hills. Strike slip faulting may accompany this event, together with gravitational collapse-induced normal faulting.