Correntropy: Answer to non-Gaussian noise in modern SLAM applications?

The problem of non-Gaussian noise/outliers has been intrinsic in modern Simultaneous Localization and Mapping (SLAM) applications. Despite numerous algorithms in SLAM, it has become crucial to address this problem in the realm of modern robotics applications. This work focuses on addressing the above-mentioned problem by incorporating the usage of correntropy in SLAM. Before correntropy, multiple attempts of dealing with non-Gaussian noise have been proposed with significant progress over time but the underlying assumption of Gaussianity might not be enough in real-life applications in robotics.Most of the modern SLAM algorithms propose the `best' estimates given a set of sensor measurements. Apart from addressing the non-Gaussian problems in a SLAM system, our work attempts to address the more complex part concerning SLAM: (a) If one of the sensors gives faulty measurements over time (`Faulty' measurements can be non-Gaussian in nature), how should a SLAM framework adapt to such scenarios? (b) In situations where there is a manual intervention or a 3rd party attacker tries to change the measurements and affect the overall estimate of the SLAM system, how can a SLAM system handle such situations?(addressing the Self Security aspect of SLAM). Given these serious situations how should a modern SLAM system handle the issue of the previously mentioned problems in (a) and (b)? We explore the idea of correntropy in addressing the above-mentioned problems in popular filtering-based approaches like Kalman Filters(KF) and Extended Kalman Filters(EKF), which highlights the `Localization' part in SLAM. Later on, we propose a framework of fusing the odometeries computed individually from a stereo sensor and Lidar sensor (Iterative Closest point Algorithm (ICP) based odometry). We describe the effectiveness of using correntropy in this framework, especially in situations where a 3rd party attacker attempts to corrupt the Lidar computed odometry. We extend the usage of correntropy in the `Mapping' part of the SLAM (Registration), which is the highlight of our work. Although registration is a well-established problem, earlier approaches to registration are very inefficient with large rotations and translation. In addition, when the 3D datasets used for alignment are corrupted with non-Gaussian noise (shot/impulse noise), prior state-of-the-art approaches fail. Our work has given birth to another variant of ICP, which we name as Correntropy Similarity Matrix ICP (CoSM-ICP), which is robust to large translation and rotations as well as to shot/impulse noise. We verify through results how well our variant of ICP outperforms the other variants under large rotations and translations as well as under large outliers/non-Gaussian noise. In addition, we deploy our CoSM algorithm in applications where we compute the extrinsic calibration of the Lidar-Stereo sensor as well as Lidar-Camera calibration using a planar checkerboard in a single frame. In general, through results, we verify how efficiently our approach of using correntropy can be used in tackling non-Gaussian noise/shot noise/impulse noise in robotics applications

Securing a UAV Using Features from an EEG Signal

This thesis focuses on an approach which entails the extraction of Beta component of the EEG (Electroencephalogram) signal of a user and uses his/her EEG beta data to generate a random AES (Advanced Encryption Standard) encryption key. This Key is used to encrypt the communication between the UAVs (Unmanned aerial vehicles) and the ground control station. UAVs have attracted both commercial and military organizations in recent years. The progress in this field has reached significant popularity, and the research has incorporated different areas from the scientific domain. UAV communication became a significant concern when an attack on a Predator UAV occurred in 2009, which allowed the hijackers to get the live video stream. Since a UAVs major function depend on its onboard auto pilot, it is important to harden the system against vulnerabilities. In this thesis, we propose a biometric system to encrypt the UAV communication by generating a key which is derived from Beta component of the EEG signal of a user. We have developed a safety mechanism that gets activated in case the communication of the UAV from the ground control station gets attacked. This system was validated on a commercial UAV under malicious attack conditions during which we implement a procedure where the UAV return safely to an initially deployed "home" position

Charting Circumstellar Chemistry of Carbon-rich AGB Stars

Stars of low to intermediate initial masses (0.8 - 8 M⊙) enter the asymptotic giant branch (AGB) phase during their late evolution. This phase is characterised by intense mass loss from the stellar surface into the interstellar medium (ISM), eventually leading to the formation of an extended circumstellar envelope (CSE) composed of the ejected gas and dust around the star. These stars are also the birthplace of many heavy elements. AGB stars thus contribute heavily to the chemical replenishment of the ISM in galaxies, by enriching it with the nuclear-processed material dredged up from the stellar interiors. This makes AGB CSEs very interesting cosmic chemical laboratories, sites of diverse, and often complex chemistry.\ua0Based on the relative abundances of carbon and oxygen in their atmospheres, AGB stars are categorised into C-rich and O-rich, the carbon stars being more chemically complex than their oxygen-rich counterparts. The study of molecular line emission from AGB CSEs is of particular interest, as it can help constrain both the physical and chemical characteristics of the envelopes. However, much of our current knowledge of AGB circumstellar chemistry, particularly of the C-rich type, is based on observations and models of a single object, IRC +10 216, which is often regarded as an archetypical carbon star. Advances in instrumentation, including the development of high angular resolution interferometers, have opened up possibilities for observational studies of additional sources in unprecedented detail.\ua0This thesis summarises our current understanding of the chemistry in C-rich CSEs, and presents the first spatially-resolved, unbiased spectral surveys of the circumstellar molecular emission from multiple carbon stars other than IRC +10216. ALMA band 3 spectral surveys of three C-rich AGB stars reveal the morphological and chemical complexity of their CSEs. We compare the results obtained from these surveys with those of IRC +10216, and discuss their implications for the generalised understanding of the chemistry in carbon star CSEs. By obtaining well-constrained estimates of the emission region sizes and circumstellar abundances of a variety of molecular species, this work aims to provide updates to existing chemical models, and put to test the archetype status attributed to IRC +10216 in the literature

Internal Newtonian Flow Due to a Cylinder Undergoing Longitudinal and Torsional Oscillations of Different Frequencies

The unsteady flow of an incompressible viscous fluid contained in a cylinder of infinite length, subject to longitudinal and torsional oscillations of different frequencies is examined. Analytical expressions for the velocity field, shear stresses, drag on the cylinder, work done and the drag coefficients are obtained

Advances in the Use of Regulatory T-Cells for the Prevention and Therapy of Graft-vs.-Host Disease

Regulatory T (Tregs) cells play a crucial role in immunoregulation and promotion of immunological tolerance. Adoptive transfer of these cells has therefore been of interest in the field of bone marrow and solid organ transplantation, autoimmune diseases and allergy medicine. In bone marrow transplantation, Tregs play a pivotal role in the prevention of graft-verus-host disease (GvHD). This has generated interest in using adoptive Treg cellular therapy in the prevention and treatment of GvHD. There have been several barriers to the feasibility of Treg cellular therapy in the setting of hematopoietic stem cell transplantation (HSCT) which include low Treg concentration in peripheral blood, requiring expansion of the Treg population; instability of the expanded product with loss of FoxP3 expression; and issues related to the purity of the expanded product. Despite these challenges, investigators have been able to successfully expand these cells both in vivo and in vitro and have demonstrated that they can be safely infused in humans for the prevention and treatment of GvHD with no increase in relapse risk or infections risk

Wetlands and diversity of angiosperm macrophytes in wetlands of Pune district in Maharashtra, India

The wetlands and wetland macrophytes play crucial role in the ecosystem with direct as well as indirect benefits of uncountable value. A study was undertaken to document angiospermic wetland macrophytes in Pune district, Maharashtra state, India. Results of the study revealed that, there are 11 categories of wetlands in Pune district including seven natural and four man- made. These wetlands harbour 457 angiosperms belonging to 72 families. Of these, 457 taxa, 204 taxa are under different categories as per IUCN, while 253 are not evaluated. Among recorded taxa, one is ‘Critically Endangered’ (Eriocaulon santapaui), three ‘Endangered’ (Iphigenia stellata, Eriocaulon richardianum and Dimeria hohenackeri), two ‘Vulnerable’ (Isachne bicolor and Utricularia albocaerulea) and 198 taxa are ‘Least concerned’. Total 67 Indian endemic taxa are recorded from the wetlands in the study area

Fluorescence and FTIR markers for different taxa of Gymnema drug complex from Maharashtra

Gymnema sylvestre known as Madhunashini / Gudmar and being commercially traded as a remedy of diabetes. The other taxa of this genus are also used as alternative drugs. The drug standards are available for the former species but not for the alternative taxa. In the present study, four taxa of Gudmar complex are evaluated to develop drug identification markers through fluorescence study and FTIR analysis. These markers are successful in distinguishing individual drug samples. The study will help to find out the purity of the samples and also for verification of drugs