| 1. |
- Arain, Muhammad Asif, 1983-, et al.
(författare)
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Efficient Measurement Planning for Remote Gas Sensing with Mobile Robots
- 2015
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Ingår i: 2015 IEEE International Conference on Robotics and Automation (ICRA). - Washington, USA : IEEE. - 9781479969234 ; , s. 3428-3434
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Konferensbidrag (refereegranskat)abstract
- The problem of gas detection is relevant to manyreal-world applications, such as leak detection in industrialsettings and surveillance. In this paper we address the problemof gas detection in large areas with a mobile robotic platformequipped with a remote gas sensor. We propose a novelmethod based on convex relaxation for quickly finding anexploration plan that guarantees a complete coverage of theenvironment. Our method proves to be highly efficient in termsof computational requirements and to provide nearly-optimalsolutions. We validate our approach both in simulation andin real environments, thus demonstrating its applicability toreal-world problems.
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| 2. |
- Arain, Muhammad Asif, 1983-
(författare)
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Efficient Remote Gas Inspection with an Autonomous Mobile Robot
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human-caused greenhouse gas emissions are one of the major sources of global warming, which is threatening to reach a tipping point. Inspection systems that can provide direct information about critical factors causing global warming, such as systems for gas detection and location of gas sources, are urgently needed to analyze the fugitive emissions and take necessary actions.This thesis presents an autonomous robotic system capable of performing efficient exploration by selecting informative sampling positions for gas detection and gas distribution mapping – the Autonomous Remote Methane Explorer (ARMEx). In the design choice of ARMEx, a ground robot carries a spectroscopybased remote gas sensor, such as a Remote Methane Leak Detector (RMLD), that collects integral gas measurements along up to 30 m long optical-beams. The sensor is actuated to sample a large area inside an adjustable field of view, and with the mobility of the robot, adaptive sampling for high spatial resolution in the areas of interest is made possible to inspect large environments.In a typical gas sampling mission, the robot needs to localize itself and plan a traveling path to visit different locations in the area, which is a largely solved problem. However, the state-of-the-art prior to this thesis fell short of providing the capability to select informative sampling positions autonomously. This thesis introduces efficient measurement strategies to bring autonomy to mobile remote gas sensing. The strategies are based on sensor planning algorithms that minimize the number of measurements and distance traveled while optimizing the inspection criteria: full sensing coverage of the area for gas detection, and suitably overlapping sensing coverage of different viewpoints around areas of interest for gas distribution mapping.A prototype implementation of ARMEx was deployed in a large, real-world environment where inspection missions performed by the autonomous system were compared with runs teleoperated by human experts. In six experimental trials, the autonomous system created better gas maps, located more gas sources correctly, and provided better sensing coverage with fewer sensing positions than human experts.
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| 3. |
- Al-Shishtawy, Ahmad, 1978-, et al.
(författare)
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Achieving Robust Self-Management for Large-Scale Distributed Applications
- 2010
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Ingår i: Self-Adaptive and Self-Organizing Systems (SASO), 2010 4th IEEE International Conference on. - : IEEE Computer Society. - 9781424485376 ; , s. 31-40
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Konferensbidrag (refereegranskat)abstract
- Achieving self-management can be challenging, particularly in dynamic environments with resource churn (joins/leaves/failures). Dealing with the effect of churn on management increases the complexity of the management logic and thus makes its development time consuming and error prone. We propose the abstraction of robust management elements (RMEs), which are able to heal themselves under continuous churn. Using RMEs allows the developer to separate the issue of dealing with the effect of churn on management from the management logic. This facilitates the development of robust management by making the developer focus on managing the application while relying on the platform to provide the robustness of management. RMEs can be implemented as fault-tolerant long-living services. We present a generic approach and an associated algorithm to achieve fault-tolerant long-living services. Our approach is based on replicating a service using finite state machine replication with a reconfigurable replica set. Our algorithm automates the reconfiguration (migration) of the replica set in order to tolerate continuous churn. The algorithm uses P2P replica placement schemes to place replicas and uses the P2P overlay to monitor them. The replicated state machine is extended to analyze monitoring data in order to decide on when and where to migrate. We describe how to use our approach to achieve robust management elements. We present a simulation-based evaluation of our approach which shows its feasibility.
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| 4. |
- Arain, Muhammad Asif, 1983-, et al.
(författare)
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Global coverage measurement planning strategies for mobile robots equipped with a remote gas sensor
- 2015
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Ingår i: Sensors. - Basel, Switzerland : MDPI. - 1424-8220. ; 15:3, s. 6845-6871
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Tidskriftsartikel (refereegranskat)abstract
- The problem of gas detection is relevant to many real-world applications, such as leak detection in industrial settings and landfill monitoring. In this paper, we address the problem of gas detection in large areas with a mobile robotic platform equipped with a remote gas sensor. We propose an algorithm that leverages a novel method based on convex relaxation for quickly solving sensor placement problems, and for generating an efficient exploration plan for the robot. To demonstrate the applicability of our method to real-world environments, we performed a large number of experimental trials, both on randomly generated maps and on the map of a real environment. Our approach proves to be highly efficient in terms of computational requirements and to provide nearly-optimal solutions.
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| 5. |
- Asif, Muhammad, 1978-
(författare)
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Electrochemical Biosensors Based on Functionalized Zinc Oxide Nanorods
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The semi-conductor zinc oxide (ZnO), a representative of group II-VI has gained substantial interest in the research community due to its novel properties and characteristics. ZnO a direct band gap (3.4eV) semi-conductor has a stable wurtzite structure. Recently ZnO have attracted much interest because of its unique piezoelectric, semiconducting, catalytic properties and being biosafe and biocompatible morphology combined with the easiness of growth. This implies that ZnO has a wide range of applications in optoelectronics, sensors, transducers, energy conversion and medical sciences. This thesis relates specifically to biosensor technology and pertains more particularly to novel biosensors based on multifunctional ZnO nanorods for biological, biochemical and chemical applications.The nanoscale science and engineering have found great promise in the fabrication of novel nano-biosensors with faster response and higher sensitivity than of planar sensor configurations. This thesis aims to highlight recent developments in materials and techniques for electrochemical biosensing, design, operation and fabrication. Rapid research growths in biomaterials, especially the availability and applications of a vast range of polymers and copolymers associated with new sensing techniques have led to remarkable innovation in the design and fabrication of biosensors. Specially nanowires/nanorods and due to their small dimensions combined with dramatically increased contact surface and strong binding with biological and chemical reagents will have important applications in biological and biochemical research. The diameter of these nanostructures is usually comparable to the size of the biological and chemical species being sensed, which intuitively makes them represent excellent primary transducers for producing electrical signals. ZnO nanostructures have unique advantages including high surface to volume ratio, nontoxicity, chemical stability, electrochemical activity, and high electron communication features. In addition, ZnO can be grown as vertical nanorods and has high ionic bonding (60%), and they are not very soluble at biological pH-values. All these facts open up for possible sensitive extra/intracellular ion measurements. New developments in biosensor design are appearing at a high rate as these devices play increasingly important roles in daily life. In this thesis we have studied calcium ion selectivity of ZnO nanorods sensors using ionophore membrane coatings in two research directions: first, we have adjusted the sensor with sufficient selectivity especially for Ca2+, and the second is to have enough sensitivity for measuring Ca2+ concentrations in extra and intracellular media. The sensor in this study was used to detect and monitor real changes of Ca2+ across human fat cells and frog cells using changes in the electrochemical potential at the interface in the intracellular microenvironment.The first part of the thesis presents extracellular studies on calcium ions selectively by using ZnO nanorods grown on the surface of a silver wire (250 μm in diameter) with the aim to produce proto-type electrochemical biosensors. The ZnO nanorods exhibited a Ca2+-dependent electrochemical potentiometric behavior in an aqueous solution. The potential difference was found to be linear over a large logarithmic concentration range (1μM to 0.1M) using Ag/AgCl as a reference electrode. To make the sensors selective for calcium ions with sufficient selectivity and stability, plastic membrane coatings containing ionophores were applied. These functionalized ZnO nanorods sensors showed a high sensitivity (26.55 mV/decade) and good stability.In the second part, the intracellular determination of Ca2+ was performed in two types of cells. For that we have reported functionalized ZnO nanorods grown on the tip of a borosilicate glass capillary (0.7 μm in diameter) used to selectively measure the intracellular free Ca2+ concentration in single human adipocytes and frog oocytes. The sensor exhibited a Ca2+ linear electrochemical potential over a wide Ca2+ concentration range (100 nM to 10 mM). The measurement of the Ca2+ concentration using our ZnO nanorods based sensor in living cells were consistent with values of Ca2+ concentration reported in the literature.The third and final part, presents the calcium ion detection functionalized ZnO nanorods coupled as an extended gate metal oxide semiconductor field effect transistor (MOSFET). The electrochemical response from the interaction between the ZnO nanorods and Ca2+ in an aqueous solution was coupled directly to the gate of a MOSFET. The sensor exhibited a linear response within the range of interest from 1 μM to 1 mM. Here we demonstrated that ZnO nanorods grown on a silver wire can be combined with conventional electronic component to produce a sensitive and selective biosensor.
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| 6. |
- Asif, Muhammad H, 1978-, et al.
(författare)
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Functionalized zinc oxide nanorod with ionophore-membrane coatingas an intracellular Ca2+ selective sensor
- 2009
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Ingår i: Applied Physics Letters. - : EBSCO/American Institute of Physics. - 0003-6951 .- 1077-3118. ; 95:2, s. 23703-
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Tidskriftsartikel (refereegranskat)abstract
- The tip of a borosilicate glass capillary with functionalized hexagonal ZnO nanorods was used to make a sensitive electrochemical intracellular Ca2+ sensor. To adjust the sensor for Ca2+ measurements with sufficient selectivity and stability, polyvinyl chloride (PVC) membrane containing Ca2+ ionophores were coated on the surface. The membrane covered ZnO nanorods exhibited a Ca2+-dependent electrochemical potential difference versus an Ag/AgCl reference electrode. The potential difference was linear over a large concentration range (100 nM to 10 mM). The measurements of Ca2+ concentrations using our ZnO nanorods sensor in human fat cells or in frog egg cells were consistent with values of Ca2+ concentrations reported in the literature. This nanoelectrode device paves the way to measurements of intracellular biochemical species in specific locations within single living cells.
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| 7. |
- Asif, Muhammad, 1978-, et al.
(författare)
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Selective calcium ion detection with functionalized ZnO nanorods-extendedgate MOSFET
- 2009
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Ingår i: Biosensors & bioelectronics. - : ELSEVIER. - 0956-5663 .- 1873-4235. ; 24:11, s. 3379-3382
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Tidskriftsartikel (refereegranskat)abstract
- Zinc oxide nanorod-extended gate field effect transistor (MOSFET) is demonstrated for the detection of calcium (Ca2+) ions. ZnO nanorods were grown on the surface of a silver wire to produce an electrochemical nanosensor for selectively detecting Ca2+. The electrochemical response from the interaction between the ZnO nanorods and Ca2+ in an aqueous solution is coupled directly to the gate of a field effect transistor (MOSFET). The induced voltage change on the gate results in a measureable current response. In order to adapt the sensors for Ca2+ ions measurements in biological fluids with sufficient selectivity and stability, a plastic membrane coating containing ionophores was applied on the nanorods. The sensor exhibited a linear response within the range of interest from 1 μM to 1 mM. This work demonstrates a simple technique for sensitive detection of Ca2+ ions by efficient transfer of the chemical response directly to a standard electronic component producing a low impedance signal.
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| 8. |
- Asif, Muhammad, 1978-, et al.
(författare)
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Studies on Calcium Ion Selectivity of ZnO Nanowire Sensors Using Ionophore Membrane Coatings
- 2008
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Ingår i: Research Letters in Nanotechnology. - : Hindawi Publishing Corporation. - 1687-6849 .- 1687-6857. ; 2008:Article ID 701813
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Tidskriftsartikel (refereegranskat)abstract
- Zinc oxide nanorods with 100nm diameter and 900nm length were grown on the surface of a silver wire (0.25mm in diameter) with the aim to produce electrochemical nanosensors. It is shown that the ZnO nanorods exhibit a Ca2+-dependent electrochemical potentiometric behavior in an aqueous solution. The potential difference was found to be linear over a large logarithmic concentration range (1 μM to 0.1 M) using Ag/AgCl as a reference electrode and the response time was less than one minute. In order to adapt the sensors for calcium ion measurements in biological fluids with sufficient selectivity and stability, plastic membrane coatings containing ionophores were applied. These functionalized ZnO nanorods sensors showed a high sensitivity (26.55 mV/decade) and good stability.
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