Search or add a thesis

Advanced Search (Beta)
Home > Analysis of Spin and Recovery Characteristics of Multirole Fighter Aircraft.

Analysis of Spin and Recovery Characteristics of Multirole Fighter Aircraft.

Thesis Info

Access Option

External Link

Author

Malik, Bilal

Program

PhD

Institute

Air University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2018

Thesis Completion Status

Completed

Subject

Engineering & Technology

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/11054/1/Bilal-Malik-PhD-AvE-Thesis-Final.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727702635

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


The purpose of the present research is to investigate the spin and recovery characteristics of a high performance fighter configuration that exhibits yawing moment asymmetry at high angles of attack. High fidelity aerodynamic model, in a look-up-tables form, is developed using experimental data from static, coning, and oscillatory coning rotary balance wind tunnel tests. As a first step, all the possible steady spin modes, along with their sensitivity to control settings, are predicted from the aircraft flight dynamic model. Influence of high alpha yawing moment asymmetry on the spin recovery characteristics is inferred from the spin equilibria plots. Results from dynamical systems theory are applied to determine local stability characteristics of aircraft around steady spin states. The complete set of dynamic modes of aircraft in spin is evaluated and mode content in each of the motion variable is determined using modal decomposition. Investigation of dynamic characteristics of predicted spin modes is performed using six degrees-of-freedom time history simulations which showed that both, right and left flat spins are oscillatory and divergent. Standard spin recovery piloting strategies are investigated by performing numerical simulations of flat spins in open-loop configuration. Numerical simulations show that for fighter configuration with high-alpha yawing moment asymmetry, same spin recovery strategies when applied to left and right flat spins produce contradicting results. The proposed spin recovery strategies effectively reduced the recovery time for left flat spins. However, aircraft''s inherent tendency to yaw towards right due to high-alpha yawing moment asymmetry renders proposed spin recovery strategies ineffective in accelerating recovery of right flat spins. Performance of a gain scheduled flight control law in automatic spin recovery is also evaluated by performing numerical simulations of left and right flat spins in closed-loop configuration. The control law also reduces the recovery time of the left flat spins but is ineffective in aiding the recovery of the right flat spins. Simulations in closed loop configuration show that the large amplitude oscillations in angle of attack and sideslip, observed in open-loop configuration, are significantly damped by the flight control law.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

ضبط کو آزما رہا ہوں میں

ضبط کو آزما رہا ہوں میں
بے وفا سے نبھا رہا ہوں میں

لوگ کہنے لگے ہیں دیوانہ
ایسے اعزاز پا رہا ہوں میں

بخدا میرے بس کی بات نہیں
جتنے صدمے اٹھا رہا ہوں میں

میرے احباب کو مبارک ہو
چھوڑ کر شہر جا رہا ہوں میں

عشق کی آگ کیوں نہیں بجھتی
کب سے تائبؔ بجھا رہا ہوں میں

Jugni, Dhola and Mahiya: Comparing

Among the amazing variety of forms of poetic expression by the folk of the Punjab region, this essay has selected three genres: mahiya, dhola and jugni. The study is meant to compare these three genres of Punjabi folklore, in their evolution, structure, expression and themes. The study finds that the three genres are very old in time origin and tracing their exact origins in history is impossible, only few hints are available. Their structures are variable, as mahiya has a fixed structure, dhola has rather loose structure giving more freedom to the singer-poet, and jugni has a specific meter in certain lines, but it has freedom to repeat some lines for perfect expression of the melody. The structures in fact follow the tunes, distinct for each genre. Three genres have many themes common, but jugni has spirituality as dominant theme, dhola has expression of love as dominant them and mahiya has now become quite inclusive, but it originated as expression of love and it still retains that character in its core. The folk heart of Punjab has endeared these three genres so much that these are appreciated far and wide in original tunes, but new experiments of tunes and themes are also underway. Being a true mirror of simple unsophisticated villagers these folk songs would lose popularity if these villagers become sophisticated hence the need for their preservation is highlighted in this study.

Advanced Image Reconstruction Algorithms in Mri

Magnetic Resonance Imaging (MRI) is a non-invasive and non-ionizing medical imaging technique that provides essential clinical information about both the anatomy and physiology of the human body. One of the major limitations of MRI is long scan time. The reduction in scan time is vital for many MRI applications. There are two different stages in MRI scanning process and multiple strategies can be applied to reduce the overall scan time: (i) MRI data acquisition time and (ii) processing the acquired data to reconstruct artifact free high-resolution image (reconstruction time). This thesis mainly focusesonthesecondparti.e. toreducethescantimeofMRI.ThefirstphaseofthisthesispresentsanovelimplementationofGPUbasedSENSEalgorithm(apMRImethod), that employs QR decomposition for the inversion of the rectangular encoding matrix. For a fair comparison, the performance of the proposed GPU based SENSE reconstructionisevaluatedagainstsingleandmulti-coreCPUusingOpenMP.Severalexperiments against various Acceleration Factors (AFs) are performed using multichannel phantom, in-vivo human head and cardiac datasets. Experimental results show that the proposed GPU implementation significantly reduces the computation time of SENSE reconstructionascomparedtomulti-coreCPUwithoutanydegradationinthequalityofthereconstructed images. In the second phase, an iterative sequential combination of Linear Conjugate Gradient (LCG) based pMRI algorithm with p-thresholding based CS algorithm for MR image reconstruction is proposed to reconstruct images from a highly under-sampled data. Theproposedmethod(CGSENSE-CS)exploitsthecomplementarycharacteristics of CGSENSE (making reconstruction algorithm faster and accurate) and CS (efficient method in removing noise) to improve the reconstruction results. The proposed method is compared with contemporary methods CG-SENSE and `1-SPIR-iT, using Phantom and in-vivo human head datasets. Experimental results show that CGSENSE-CS (proposed method) achieves better Artifact Power (AP), Root Mean Square Error (RMSE) and high Peak Signal-to-Noise Ratio (PSNR). Second major limitation of the current MRI technology is that it detects and diagnoses abnormalities in the patient’s body based on the contrast between different tissues. Absolute measurements from a single tissue have proven extremely valuable for the diagnosis, prognosis, and therapeutic assessment. The lack of quantification in current MRI limits an objective evaluation, leads to a variability in interpretation, and potentially limits the utility of the technology in some clinical scenarios. However, Magnetic Resonance Fingerprinting (MRF), a latest innovation in MRI, can quantitatively examine many magnetic resonance tissue parameters, simultaneously. MRF algorithm in current form is highly computation and memory intensive because it inherently requires all the possible combinations of tissue parameters and inner product is computed between the observedsignalandeverysinglecombinationofthetissueparameters. Inthethirdphase ofthisPhDthesis,MRFalgorithmisacceleratedbyproposingaparallelframeworkand implementing it on a parallel architecture.