Modeling and nonlinear adaptive control of an aerial manipulation system

Autonomous aerial robots have become an essential part of many civilian and military applications. The workspace and agility of these vehicles motivated great research interest resulting in various studies addressing their control architectures and mechanical configurations. Increasing autonomy enabled them to perform tasks such as surveillance, inspection and remote sensing in hazardous and challenging environments. The ongoing research promises further contributions to the society, in both theory and practice. To furthermore extend their vast applications, aerial robots are equipped with the tools to enable physical interaction with the environment. These tasks represent a great challenge due to the technological limitations as well as the lack of sophisticated methods necessary for the control of the system to perform desired operations in an efficient and stable manner. Modeling and control problem of an aerial manipulation is still an open research topic with many studies addressing these issues from different perspectives. This thesis deals with the nonlinear adaptive control of an aerial manipulation system (AMS). The system consists of a quadrotor equipped with a 2 degrees of freedom (DOF) manipulator. The complete modeling of the system is done using the Euler-Lagrange method. A hierarchical nonlinear control structure which consists of outer and inner control loops has been utilized. Model Reference Adaptive Controller (MRAC) is designed for the outer loop where the required command signals are generated to force the quadrotor to move on a reference trajectory in the presence of mass uncertainties and reaction forces coming from the manipulator. For the inner loop, the attitude dynamics of the quadrotor and the joint dynamics of the 2-DOF robotic arm are considered as a fully actuated 5-DOF unified part of the AMS. Nonlinear adaptive control has been utilized for the low-level controller where the changes in inertias have been considered. The proposed controller is tested on a high fidelity AMS model in the presence of uncertainties, wind disturbances and measurement noise, and satisfactory trajectory tracking performance with improved robustness is achieved

Error Rate Analysis of GF(q) Network Coded Detect-and-Forward Wireless Relay Networks Using Equivalent Relay Channel Models

This paper investigates simple means of analyzing the error rate performance of a general q-ary Galois Field network coded detect-and-forward cooperative relay network with known relay error statistics at the destination. Equivalent relay channels are used in obtaining an approximate error rate of the relay network, from which the diversity order is found. Error rate analyses using equivalent relay channel models are shown to be closely matched with simulation results. Using the equivalent relay channels, low complexity receivers are developed whose performances are close to that of the optimal maximum likelihood receiver.Comment: 28 pages, 10 figures. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Articulatory and bottleneck features for speaker-independent ASR of dysarthric speech

The rapid population aging has stimulated the development of assistive devices that provide personalized medical support to the needies suffering from various etiologies. One prominent clinical application is a computer-assisted speech training system which enables personalized speech therapy to patients impaired by communicative disorders in the patient's home environment. Such a system relies on the robust automatic speech recognition (ASR) technology to be able to provide accurate articulation feedback. With the long-term aim of developing off-the-shelf ASR systems that can be incorporated in clinical context without prior speaker information, we compare the ASR performance of speaker-independent bottleneck and articulatory features on dysarthric speech used in conjunction with dedicated neural network-based acoustic models that have been shown to be robust against spectrotemporal deviations. We report ASR performance of these systems on two dysarthric speech datasets of different characteristics to quantify the achieved performance gains. Despite the remaining performance gap between the dysarthric and normal speech, significant improvements have been reported on both datasets using speaker-independent ASR architectures.Comment: to appear in Computer Speech & Language - https://doi.org/10.1016/j.csl.2019.05.002 - arXiv admin note: substantial text overlap with arXiv:1807.1094

HZSM-5 and H-ferrierite acidity modification by silylation and their activities in n-butene isomerisation

H-ZSM5 and H-Ferrierite acidities were modified by chemical liquid deposition using tetraethylorthosilicate (TEOS), silicontetratchloride (SiCl4) and triaminopropyltriethoxysilane (3-APTES). All depositions were carried out at room temperature for deposition times of 0.5 and 1 h. Reaction tests were performed in a tubular quartz fixed bed reactor at 375°C for weight hour space velocities of 22 h-1. Surface area and pore volume of the catalysts were decreased upon modifications. The least modification of acidity was achieved by TEOS. However, SiCl4 and 3-APTES deposition modification strongly decreased the number of Bronsted and Lewis acid sites. As the effect of the modification increased, total acidity of the SiCl4 modified catalyst decreased. The catalysts were tested in isomerization of n-butene. Modification decreased the activity of the catalysts, but improvement in selectivity was observed with TEOS deposition. TEOS deposition increased the selectivity of the catalysts; for synthesized H-ZSM5 from 57.95 to 63.74 percent, for commercial H-ZSM5-C from 26.78 to 32.52 percent, and for H-FER from 63.06 to 81.23 percent. However, modification with SiCl4 and 3-APTES decreased both conversion and selectivity of the parent catalysts

Seasonal and sexual variations of fatty acid composition in fillet of Capoeta erhani

The lowest lipid levels of Capoeta erhani observed in winter and vice versa in summer. The fatty acid composition of the fillets was significantly different among seasons (P0.05). The ratios of the unsaturated fatty acids (UFAs) were higher than half of the total fatty acids among all seasons. The level of PUFA was highest in autumn (25.91%), and lowest in summer (22.11%). Among seasons and sexes, the levels of total n3 PUFAs in total fatty acids changed from 15.43% to 21.89% and n6 PUFAs from 3.8% to 7.97%, respectively. The level of n3 PUFAs was present in excess that of the n6 PUFAs. The ratios of the n3 PUFAs to n6 PUFAs in the fillets of C. erhani were highest in autumn for both sexes and remarkably influenced by seasons

Regional powers contradictory leaderships: Turkey and Saudi Arabia in the Arab spring

Regional powers, their roles, and places in the future configuration of the new world order have been burning debates in academia. Yet, studies on regional powers’ projections in certain regions are quite rare both empirically and theoretically. Needless to say, regional powers have been gaining increasing importance in their respective regions that are gradually becoming autonomous. This creates an environment for them to assert their regional projections. Yet, in this responding region, there might be more than one regional power whose regional projections would possibly contradict each other due to their foreign policy considerations. In this thesis, I demonstrate how two different foreign policy oriented regional powers approach crucially important unfolding regional developments, by examining Saudi Arabia and Turkey during the Arab Spring. By accepting their leadership roles at that period, their intentions and implementations are compared and analyzed in the context of regional powers