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  1. Book ; Online: SM/VIO

    Joshi, Bharat / Damron, Hunter / Rahman, Sharmin / Rekleitis, Ioannis

    Robust Underwater State Estimation Switching Between Model-based and Visual Inertial Odometry

    2023  

    Abstract: This paper addresses the robustness problem of visual-inertial state estimation for underwater operations. Underwater robots operating in a challenging environment are required to know their pose at all times. All vision-based localization schemes are ... ...

    Abstract This paper addresses the robustness problem of visual-inertial state estimation for underwater operations. Underwater robots operating in a challenging environment are required to know their pose at all times. All vision-based localization schemes are prone to failure due to poor visibility conditions, color loss, and lack of features. The proposed approach utilizes a model of the robot's kinematics together with proprioceptive sensors to maintain the pose estimate during visual-inertial odometry (VIO) failures. Furthermore, the trajectories from successful VIO and the ones from the model-driven odometry are integrated in a coherent set that maintains a consistent pose at all times. Health-monitoring tracks the VIO process ensuring timely switches between the two estimators. Finally, loop closure is implemented on the overall trajectory. The resulting framework is a robust estimator switching between model-based and visual-inertial odometry (SM/VIO). Experimental results from numerous deployments of the Aqua2 vehicle demonstrate the robustness of our approach over coral reefs and a shipwreck.
    Keywords Computer Science - Robotics ; Computer Science - Computer Vision and Pattern Recognition
    Subject code 629
    Publishing date 2023-04-04
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Book ; Online: High Definition, Inexpensive, Underwater Mapping

    Joshi, Bharat / Xanthidis, Marios / Rahman, Sharmin / Rekleitis, Ioannis

    2022  

    Abstract: In this paper we present a complete framework for Underwater SLAM utilizing a single inexpensive sensor. Over the recent years, imaging technology of action cameras is producing stunning results even under the challenging conditions of the underwater ... ...

    Abstract In this paper we present a complete framework for Underwater SLAM utilizing a single inexpensive sensor. Over the recent years, imaging technology of action cameras is producing stunning results even under the challenging conditions of the underwater domain. The GoPro 9 camera provides high definition video in synchronization with an Inertial Measurement Unit (IMU) data stream encoded in a single mp4 file. The visual inertial SLAM framework is augmented to adjust the map after each loop closure. Data collected at an artificial wreck of the coast of South Carolina and in caverns and caves in Florida demonstrate the robustness of the proposed approach in a variety of conditions.

    Comment: IEEE Internation Conference on Robotics and Automation, 2022
    Keywords Computer Science - Computer Vision and Pattern Recognition ; Computer Science - Robotics
    Publishing date 2022-03-10
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Evaluation of a novel nanocrystalline hydroxyapatite powder and a solid hydroxyapatite/Chitosan-Gelatin bioceramic for scaffold preparation used as a bone substitute material.

    Rahman, Sharmin / Maria, Kazi Hanium / Ishtiaque, Mohammad Saif / Nahar, Arijun / DAS, Harinarayan / Hoque, Sheikh Manjura

    Turkish journal of chemistry

    2020  Volume 44, Issue 4, Page(s) 884–900

    Abstract: Artificially fabricated hydroxyapatite (HAP) shows excellent biocompatibility with various kinds of cells and tissues which makes it an ideal candidate for a bone substitute material. In this study, hydroxyapatite nanoparticles have been prepared by ... ...

    Abstract Artificially fabricated hydroxyapatite (HAP) shows excellent biocompatibility with various kinds of cells and tissues which makes it an ideal candidate for a bone substitute material. In this study, hydroxyapatite nanoparticles have been prepared by using the wet chemical precipitation method using calcium nitrate tetra-hydrate [Ca(NO
    Language English
    Publishing date 2020-08-18
    Publishing country Turkey
    Document type Journal Article
    ZDB-ID 2046471-X
    ISSN 1303-6130 ; 1300-0527
    ISSN (online) 1303-6130
    ISSN 1300-0527
    DOI 10.3906/kim-1912-40
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: SIADH in COVID 19 infection, an association or cause

    Shamarukh, Karishma / Rahman, Sharmin / Chy, Umme Kulsum / Sultana, Amina / Faruq, Mohammad Omar

    Bangladesh Critical Care Journal; Vol 8 No; 126-128 ; 2307-7654 ; 2304-0009

    A case report

    2020  Volume 2

    Abstract: One of the leading cause of hyponatremia is syndrome of inappropriate antidiuretic hormone secretion (SIADH). Various etiologies of hyponatraemia have been observed till today but its association with Covid leading to SIADH is rare. Therefore, we present ...

    Abstract One of the leading cause of hyponatremia is syndrome of inappropriate antidiuretic hormone secretion (SIADH). Various etiologies of hyponatraemia have been observed till today but its association with Covid leading to SIADH is rare. Therefore, we present a case where SIADH was associated with Covid-19 pneumonia. This was a case of a 66 years old male with multiple co-morbidities presenting with symptoms of Covid infection including generalized weakness. After confirming Covid 19 infection management was started accordingly but patient’s weakness seemed to increase. He was found to have low sodium level of 105 mmol /L and investigations confirmed that he was having SIADH. He was treated with hypertonic saline, fluid restriction and his symptoms and laboratory parameters gradually improved. Bangladesh Crit Care J September 2020; 8(2): 126-128
    Keywords covid19
    Language English
    Publishing date 2020-11-01
    Publisher Bangladesh Society of Critical Care Medicine
    Publishing country bd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Book ; Online: Navigation in the Presence of Obstacles for an Agile Autonomous Underwater Vehicle

    Xanthidis, Marios / Karapetyan, Nare / Damron, Hunter / Rahman, Sharmin / Johnson, James / O'Connell, Allison / O'Kane, Jason M. / Rekleitis, Ioannis

    2019  

    Abstract: Navigation underwater traditionally is done by keeping a safe distance from obstacles, resulting in "fly-overs" of the area of interest. Movement of an autonomous underwater vehicle (AUV) through a cluttered space, such as a shipwreck or a decorated cave, ...

    Abstract Navigation underwater traditionally is done by keeping a safe distance from obstacles, resulting in "fly-overs" of the area of interest. Movement of an autonomous underwater vehicle (AUV) through a cluttered space, such as a shipwreck or a decorated cave, is an extremely challenging problem that has not been addressed in the past. This paper proposes a novel navigation framework utilizing an enhanced version of Trajopt for fast 3D path-optimization planning for AUVs. A sampling-based correction procedure ensures that the planning is not constrained by local minima, enabling navigation through narrow spaces. Two different modalities are proposed: planning with a known map results in efficient trajectories through cluttered spaces; operating in an unknown environment utilizes the point cloud from the visual features detected to navigate efficiently while avoiding the detected obstacles. The proposed approach is rigorously tested, both on simulation and in-pool experiments, proven to be fast enough to enable safe real-time 3D autonomous navigation for an AUV.

    Comment: ICRA 2020
    Keywords Computer Science - Robotics
    Subject code 629
    Publishing date 2019-03-27
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Investigating enhanced thermoelectric performance of graphene-based nano-structures.

    Hossain, Md Sharafat / Huynh, Duc Hau / Jiang, Liming / Rahman, Sharmin / Nguyen, Phuong Duc / Al-Dirini, Feras / Hossain, Faruque / Bahk, Je-Hyeong / Skafidas, Efstratios

    Nanoscale

    2018  Volume 10, Issue 10, Page(s) 4786–4792

    Abstract: Recently, it has been demonstrated that graphene nano-ribbons (GNRs) exhibit superior thermoelectric performance compared to graphene sheets. However, the underlying mechanism behind this enhancement has not been systematically investigated and ... ...

    Abstract Recently, it has been demonstrated that graphene nano-ribbons (GNRs) exhibit superior thermoelectric performance compared to graphene sheets. However, the underlying mechanism behind this enhancement has not been systematically investigated and significant opportunity remains for further enhancement of the thermoelectric performance of GNRs by optimizing their charge carrier concentration. In this work, we modulate the carrier concentration of graphene-based nano-structures using a gate voltage and investigate the resulting carrier-concentration-dependent thermoelectric parameters using the Boltzmann transport equations. We investigate the effect of energy dependent scattering time and the role of substrate-induced charge carrier fluctuation in optimizing the Seebeck coefficient and power factor. Our approach predicts the scattering mechanism and the extent of the charge carrier fluctuation in different samples and explains the enhancement of thermoelectric performance of GNR samples. Subsequently, we propose a route towards the enhancement of thermoelectric performance of graphene-based devices which can also be applied to other two-dimensional materials.
    Language English
    Publishing date 2018-03-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/c8nr00134k
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Book ; Online: Experimental Comparison of Open Source Visual-Inertial-Based State Estimation Algorithms in the Underwater Domain

    Joshi, Bharat / Rahman, Sharmin / Kalaitzakis, Michail / Cain, Brennan / Johnson, James / Xanthidis, Marios / Karapetyan, Nare / Hernandez, Alan / Li, Alberto Quattrini / Vitzilaios, Nikolaos / Rekleitis, Ioannis

    2019  

    Abstract: A plethora of state estimation techniques have appeared in the last decade using visual data, and more recently with added inertial data. Datasets typically used for evaluation include indoor and urban environments, where supporting videos have shown ... ...

    Abstract A plethora of state estimation techniques have appeared in the last decade using visual data, and more recently with added inertial data. Datasets typically used for evaluation include indoor and urban environments, where supporting videos have shown impressive performance. However, such techniques have not been fully evaluated in challenging conditions, such as the marine domain. In this paper, we compare ten recent open-source packages to provide insights on their performance and guidelines on addressing current challenges. Specifically, we selected direct methods and tightly-coupled optimization techniques that fuse camera and Inertial Measurement Unit (IMU) data together. Experiments are conducted by testing all packages on datasets collected over the years with underwater robots in our laboratory. All the datasets are made available online.
    Keywords Computer Science - Robotics
    Subject code 004
    Publishing date 2019-04-03
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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