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Performance Analysis and Enhancement of Phased-Mimo Radar and Frequency Diverse Array Radar

Thesis Info

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External Link

Author

Khan, Waseem

Program

PhD

Institute

Air University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2015

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/728

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726851344

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Multiple-input-multiple-output (MIMO) radar and frequency diverse array (FDA) radar have gained significant attention from researchers community due to their numerous advantages over the phased-array radars. The distinguishing features of MIMO radar and FDA radar are waveform diversity and frequency diversity, respectively, while their phased-array counterpart lacks any such diversity. The hybridization form of MIMO and phased-array radars, called phased-MIMO radar, has also attracted the researchers attention due to its capability of combining the benefits of both. In this dissertation, phased-MIMO radar with closely spaced antennas and FDA radar with small inter-antenna frequency offset have been studied. To analyse the performance of radar, ambiguity function has proved to be a useful foundation. We have formulated ambiguity functions of phased- MIMO and FDA radars and derived their important mathematical properties. We have shown that FDA radar can promise better range resolution as compared to that of phased-array radar. For FDA we have proposed two novel schemes of inter-antenna frequency offset. Firstly, it is the time-dependent frequency offset as compared to the constant offset in the existing FDA. With the proposed idea a range-dependent beampattern can be synthesized with the maximum constantly illuminating the given target location. This is in contrast to the time-modulated beampattern with constant frequency offset. Secondly, we have proposed non-uniform (logarithmically increasing) frequency offset as compared to the uniform offset in the existing FDA. The proposed frequency offset promises a beampattern with a maximum only at the given target location. On the contrary, beampattern of FDA with uniform frequency offset exhibits multiple maxima in the visible range. The proposed schemes can provide a strong foundation for the development of modern radars capable of scanning the space more intelligently. We have investigated the proposed schemes only for linear array but they can be extended to planar arrays to scan the space in three dimensions.
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شیخ نذیر حسین

شیخ نذیر حسین
(ڈاکٹر محمود الحسن عارف)
’’محترم شیخ نذیر حسین صاحب بڑے عالم و محقق اور علم و فن کے قدرداں تھے، ’’معارف‘‘ ان کا محبوب رسالہ تھا، اگر ان کی کوئی چیز تیار ہوجاتی تو اس میں اشاعت کے لیے بھیجتے، معارف میں کوئی مسامحت اور فروگذاشت ہوجاتی تو فوراً توجہ دلاتے، ایسے صاحب نظر اور دیدہ ور لوگ اب عنقا ہوگئے ہیں، جب تک وہ اچھے تھے شاید ہی کوئی مہینہ ناغہ جاتا ہو کہ ان کا خط نہ آتا ہو، ادہر علالت کی وجہ سے جب ان کے خطوط آنے بند ہوئے تو میں نے شعبہ اردو، دائرہ معارف اسلامیہ لاہور کو متعدد خطوط لکھے مگر ایک خط کا بھی جواب نہیں آیا کہ دفعتہ ۲۲؍ اکتوبر کو یہ تحریر اور منسلک خط موصول ہوا تو دھک سے رہ گیا، قارئین معارف سے درخواست ہے کہ ان کے لیے دعائے مغفرت کریں!
ربنا اغفرلنا ولا خواننا الذین سبقونا بالایمان۔ ‘‘[الحشر:۱۰] (ض)
پانچ سوا پانچ فٹ منحنی سا جسم، ابرؤوں کے بال موٹے اور بے ترتیب، کلین شیو، چہرہ اور کمر قدرے خمیدہ․․․․․․ یہ تمام باتیں ذہن میں رکھیں تو اس سے فوراً شیخ نذیر حسین صاحب کی شکل و صورت ذہن میں آتی ہے․․․․․․ وہ اپنی وضع قطع اور چہرے مہرے سے قطعاً کوئی عالمِ دین یا اسکالر نظر نہیں آتے تھے، بلکہ ایک عام سے فرد دکھائی دیتے تھے۔
۷۰؁ء کی دہائی کے آخری سالوں میں جب میں اردو دائرہ معارف اسلامیہ میں پہلے پہل آیا․․․․․․ تو میں نے ڈاکٹر سید عبداﷲ، پروفیسر سید امجد الطاف، پروفیسر عبدالقیوم کے ساتھ مذکورہ بالا․․․․․․ چہرے مہرے کے ایک شخص․․․․․․ کو دیکھا تو مجھے ان کی وضع قطع کی بنا پر تعجب ہوا کہ یہ کون صاحب ہیں، پھر مجھ پر منکشف ہوا کہ یہ تو اردو دائرہ معارف اسلامیہ کے مدیر شیخ نذیر حسین...

روائع التشبيه في معلقة الملك الضليل امرئ القيس

There are two major parts of Arabic literature i.e. Prose and poetry. Arabic poetry has a great value among the critics and the literati. A series of seven poems known as Muʽallaqāt Sabʽa or ʽAšhara have a great deal in the Arabic poetry. These are the collection of seven or ten long poems that are considered as the excellent work of the pre-Islamic era known as Jāhilīya ages. These poems had been presented in the annual fair of Okaz on the occasion of pilgrimage and awarded to be the top class creative works. After that judgment, golden genres were written with silk and recited judgment, as well as taught consecutively up to date. The ancient Arabic literature is full of such like prized poems but the valuable position met to this compilation is unprecedented. Since the poets of these master pieces are among the most famous figures of the 6th century taken together, these poems provide a good picture of Budouin life besides its connotation of rhetorical semantics figurative devices are tricky during its studies. Metaphor, trope, allusive ironies, metonymies and many more colloquial figures of speech are to be observed in this renowned collection. This article deals with the rhetorical study of Muʽallaqa of Imru’ al-Qais, by identifying the magnificence of assimilation and critism on his poem, alond with the analysis and explanation of its objectives.

Isolation and Identification of Causative Agent of Potato Common Scab and Characterization of Effective Antagonistic Bacteria As Biological Control of Disease.

Potato common scab (PCS) is an economically important and worldwide crop problem.PCS produces visible blemish lesions on the surface of tubers causing diminished quality and low market value. The severity of the lesions can be ranged from superficial raised brown to corky dark brown color with pustules or deep pitted scars which were few millimeters inside the tubers. The lesions may be small, discrete or covering large area of the tubers. Based on the severity of the lesions, common scab (CS) infected tubers sometimes unable for human consumption therefore causing severe economic loss to the growers. Common scab is caused by gram positive Streptomyces. The causal agent of PCS is Streptomyces scabies. Several other Streptomyces species including Streptomyces acidiscabies, Streptomyces europaeiscabies, Streptomyces turgidiscabies, Streptomyces stelliscabies and Streptomyces bottropensis are also reported as major PCS pathogens. In this study, CS infected tubers were collected from potato growing regions of Pakistan (Potato Research Institute, PRI Sahiwal and Lahore), Spain (A Coruna, Ourense, San Esteban and Lugo) and USA (Presque Isle and Orono, Maine). From Spain, almost one hundred and twenty-four bacterial isolates were isolated from CS infected tubers. Similarly, eighteen and ten bacterial isolates were isolated from CS infected tubers collected from USA and Pakistan, respectively. Among the bacterial isolates, twentyeight, thirteen and seven isolates were confirmed as scab-related Streptomyces spp. from Spain, USA and Pakistan, respectively after 16S rRNA analysis. Further identification of selected isolates was based on species specific primers PCR amplification. 16S-23S ITS region amplification, RFLP and phylogenetic analysis revealed four, two and one isolates belonged to S. turgidiscabies, S. scabies and S. stelliscabies, respectively from Pakistan. Similarly, from Spain, sixteen isolates were confirmed as S. europaeiscabies, six, four and two isolates were confirmed as S. turgidiscabies, S. bottropensis and S. stelliscabies, respectively and thirteen isolates were confirmed as S. scabies from USA. For antagonistic bacterial isolates, CS suppressive soil was collected from agriculture potato farms of Okara, Sahiwal and Lahore having no previous CS history over last five to ten years. From suppressive soil samples, five bacterial strains were isolated (A-1, A-2, A-4, A1RT and AC12AB) and screened on the basis of their antagonistic activity assessed by disk diffusion assay against CS isolates (S. scabies). Two best antagonistic bacterial isolates namely A1RT and AC12AB were selected on the basis of strong antagonistic activity against CS pathogens and promising results for plant growth promoting attributes including IAA (Indole-3-acetic acid) production, siderophores production, nitrogen fixation, potassium and phosphate solubilization. Antagonistic bacterial strains A1RT and AC12AB were evaluated to produce IAA quantitatively and qualitatively by colorimetric and HPLC methods, respectively. After 16S rRNA analysis bacterial isolate A1RT and AC12AB were identified as Streptomyces hygroscopicus and Streptomyces violaceusniger, respectively. CS pathogenic Streptomyces strains were analyzed for the presence of pathogenicity islets (PAI) including txtAB, tomA and nec1 genes by PCR amplification. Most of the pathogenic Streptomyces strains screened in this study were found to contain all three pathogenicity related genes like txtAB, nec1 and tomA. Methanolic extracts of Streptomyces hygroscopicus strain A1RT and Streptomyces violaceusniger strain AC12AB were purified with different chromatographic techniques including thin layer chromatography (TLC), silica gel chromatography, Sephadex column chromatography, solid phase extraction and preparative HPLC. The structure of purified compound was elucidated with help of one-dimensional (1H-NMR, 13C-NMR) and twodimensional NMR (1H/1H-COSY, HMQC and HMBC) techniques. The NMR experiment reveled the structure of bioactive compound as Isatropolone C and Azalomycin from antagonistic Streptomyces hygroscopicus strain A1RT and Streptomyces violaceusniger strain AC12AB, respectively. The plant experiments were conducted to check the in-vitro effect of antagonistic bacterial strains. Greenhouse assays were designed in Pakistan, Spain and USA which resulted significant decrease in CS disease severity and increase in number of shoots, shoot length, tuber weight and number of tubers. Finally, field trials were conducted in Pakistan with antagonistic Streptomyces hygroscopicus strain A1RT, Streptomyces violaceusniger strain AC12AB and combination of strain A1RT and AC12AB used as inoculum into the potato plants. About 84, 83, and 86.1% (p<0.05) PCS disease reduction was observed in field trials when S. scabies used with Streptomyces hygroscopicus strain A1RT, Streptomyces violaceusniger strain AC12AB and a combination of Streptomyces hygroscopicus strain A1RT and Streptomyces violaceusniger, strain AC12AB respectively and selected consortia also attributed significant increase in number of shoots, length of shoots, number of tubers and yield per hectare (p<0.05).In conclusion, the selected bacteria used in this study as a consortium, A1RT (Streptomyces hygroscopicus) and AC12AB (Streptomyces violaceusniger) may be used as an excellent biological control agent for decreasing the severity of CS infection and enhancing the growth of potato plants.