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Beam and Null Steering in Fda Radars and Other Characteristics With Different Geometries

Thesis Info

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External Link

Author

Saeed, Sarah

Program

PhD

Institute

Air University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Electrical Engineering

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/13871/1/Sarah_Saeed_Electrical_Engineering_2017_HSR_Air_Univ_05.05.2017.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727710410

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Frequency diverse array (FDA) radars have gained exceptional attention from the researchers during the past decade, due to their unique range-angle and time modulated beampatterns. This range–angle dependent beampattern provides additional degrees of freedom in the spatial domain as compared to a conventional phased array radar that offers only an angle dependent beampattern. The range-angle- time dependent beampattern with the aid of advanced signal processing algorithms, has been exploited for interference suppression, beamforming, direction of arrival estimation, target tracking, and localization in radar environments. In this dissertation, utilizing the extra degrees of freedom in FDA, new beamforming schemes have been proposed. In linear frequency diverse array radars (LFDA), null steering in cognitive radar system has been proposed. This work is a ‘near to implementable form’ of cognitive radar system that offers a null steering solution both in range and angle dimensions. Similarly frequency offset selection based 3D adaptive transmit beamforming has been proposed for planar frequency diverse array radars (PFDA). The proposed scheme outsmarts other existing techniques in terms of concentrated maxima, deeper nulls and enhanced system signal to interference plus noise ratio (SINR). Previous researches have focused largely on evaluating FDA system performance in uniform linear array (ULA) and uniform rectangular arrays. Despite the advantages and implementation convenience of other array geometries, they have not been extensively investigated. In this thesis, new geometries like “circular” and “elliptical” have also been explored in the domain of frequency diversity. Normally, 3D localization of targets can be achieved with PFDA, but investigation in this dissertation validates that uniform circular frequency diverse array (UCFDA) offers much sharper localization, improved directivity and better adaptive beamforming performance as compared to PFDA. Despite the fact that UCFDA offers much improved beamforming performance and signal to interference plus noise ratio than PFDA, circular geometry is a high side lobe geometry. Investigation into elliptical frequency diverse arrays (EFDA) reveals that, much better range selectivity and reduced side lobe levels can be achieved. Extending the domain of frequency diversity further, the thesis also focuses on UCFDA and EFDA with non-uniform frequency offset. The non-uniform function selected for this purpose is tangent hyperbolic function. The proposed systems not only offers a highly configurable type array system but also outsmarts the existing non-uniform frequency offset scheme in terms of significantly reduced side lobe levels.
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بھول بھی کیسے سکتے ہیں

بھول بھی کیسے سکتے ہیں

وہ تمام دن وہ تمام غم جو گزر گئے

ہمیں یاد ہیں ہمیںیاد ہیں

وہ عجیب لوگ وہ قافلے

جو نہ رک سکے نہ بھٹک سکے

ہمیں یاد ہیں ہمیں یاد ہیں

(بھول بھی کیسے سکتے ہیں )

 

 

Pelanggaran Prinsip Etika Audit dalam Dysfunctional Audit Behavior Violation of Audit Ethics Principles in Dysfunctional Audit Behavior

Dysfunctional Audit Behavior (DAB) poses a significant threat to the integrity of audit practices and ethical standards. This research delves into the intricate web of ethical violations within DAB, examining the deviations from established ethical principles in the field of auditing. The study employs a comprehensive qualitative research methodology, incorporating interviews, case analyses, and ethical frameworks to unravel the underlying factors contributing to these violations. The research uncovers the multifaceted nature of ethical breaches within DAB, focusing on issues related to impartiality, integrity, objectivity, professionalism, and confidentiality. Through in-depth analyses of real-world cases and interviews with auditors, clients, and regulatory bodies, this study aims to identify patterns and motivations driving auditors towards unethical practices. Moreover, the research explores the impact of these violations on the credibility of audit reports and the overall trust in the auditing profession. The findings of this research not only shed light on the root causes of ethical misconduct but also offer valuable insights for regulatory bodies, audit firms, and educators. By understanding the complexities of DAB, stakeholders can develop targeted strategies to prevent and mitigate these violations effectively. Strengthening ethical education, enhancing regulatory oversight, and fostering a culture of integrity within audit organizations emerge as key recommendations from this study.

Ecological Relationship Among Ground Water Breeding Mosquitoes and Population Dynamics of Karachi and Thatta District

The present research of larval breeding sites was performed. The larvae of 14-species of mosquito comprising 3-genera viz. Anopheles, Culex and Aedes were collected from different ground water habitats in Karachi and Thatta of Sindh province, Pakistan, during four years period from 2004 to 2007. A total of 94800 mosquito larvae were collected, out of all these larvae 13.82% was belonged to genus Anopheles, 81.03% to genus Culex and only 4.77% belonged to genus Aedes. Over all collection during 2004 to 2007, the Anopheles was found 16.00%, 14.11%, 11.93% and 13.38% respectively. While Culex larvae were found 79.90%, 82.41%, 80.84% and 82.31respectively during 2004 to 2007, whereas Aedes larval population was recorded as 4.09%, 3.48%, 7.23% and 4.31% during four years. Among Anopheles six species were found which are An. annularis, An.culicifacies, An. pulcherrimus, An. nigerrimus, An. stephensi and An. subpictus (12,974 larvae were studied and identified). Similarly six species of Culex genus (77,192 larvae were studied and indentified) as Cx.xx bitaeniorhynchus, Cx. fuscocephalus, Cx. pipiens fatigans, Cx. pseudovishnui, Cx. tritaeniorhynchus and Cx.vagans. In the same way two species of Aedes, aegypti and Aedes albopictus were also found. Culex genus was the most common and showed highest percentage among Culex species, the Cx. tritaeniorhynchus and Cx. pipiens fatigans exhibited the greatest range of habitat. Among Anopheles, An. culicufacies and An. stephensi breeds in almost any available type of water, but An. stephensi was inversely related to temperature as for as Aedes mosquito concerned, Ae. aegypti percentage was always very high as compared to Aedes albopictus. Highest number mostly was found in the month of October, every year. It is to be noted that larvae fauna depends not only the type of habitat but also on the physical and chemical composition. Some species have positive association and some restricted only in clean water. In the present thesis different experiments were conducted for the resistance on mosquito larvae of District Karachi and Thatta, Mosquito larvae were exposed to neem formulation, the Biosal (10 EC) available locally in the market, a synthetic pyrethroid, deltamethrin (10 EC) andxxi Acorus calamus extract were used. The LC 50 values were calculated simultaneously the two enzyme (GOT, GPT) were estimated in mosquito larvae. Residue analysis and rate of biogradation was also noted by HPLC The LC 50 values of Biosal deltamethrin and Acorus calamus extract against mosquito larvae were computed as 1605.05 ppm, 0.6119 ppm and 70.64 ppm respectively. The enzyme activity pattern and inhibition by Biosal, deltamethrin and Acorus calamus extract were estimated after treatment with LC 50 values of the under test insecticides. The inhibition of GOT produced by biosal, deltamethrin and Acorus calamus extract was calculated as 5.78%, 26.66% and 5.83% respectively. Whereas for GPT the inhibition was 3.95%, 19.65% and 13.77% respectively. The residue analysis by HPLC shows that 97.79%, 87.87% and 78.18% residue of biosal were detected in 24, 48, and 72 hours exposed samples as compared to standard biosal sample. While 98.66 %, 98.49% and 70.45% residues of deltamethrin were detected in 24 hours, 48 hours and 72 hours exposed samples. Whereas 94.63%, 71.65% and 66.25 % residue of Acorus calamus extract were found in 24 hours, 48 hours and 72 hoursxxii exposed larvae. The residue analysis by HPLC indicated that the biodegradation is faster in biosal as compared to Deltamethrin and Acorus calamus samples, which indicate that Biosal degrade quicker and this may be concluded that toxicity of pesticide if compared to each other, is in the following sequence Biosal > Acorus calamus > Deltamethrin. Enzyme inhibition values and HPLC residue analysis, possibly proves the hypothesis that the pesticides obtained from neem and other plant and trees are not only less harmful but safer for our environment, but less prone to the development of resistance.