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  • Ringaby, Erik, et al. (författare)
  • Co-aligning Aerial Hyperspectral Push-broom Strips for Change Detection
  • 2010
  • Ingår i: Electro-Optical Remote Sensing, Photonic Technologies, and Applications IV. - 978-0-8194-8353-9
  • Konferensbidrag (refereegranskat)abstract
    • We have performed a field trial with an airborne push-broom hyperspectral sensor, making several flights over the same area and with known changes (e.g., moved vehicles) between the flights. Each flight results in a sequence of scan lines forming an image strip, and in order to detect changes between two flights, the two resulting image strips must be geometrically aligned and radiometrically corrected. The focus of this paper is the geometrical alignment, and we propose an image- and gyro-based method for geometric co-alignment (registration) of two image strips. The method is particularly useful when the sensor is not stabilized, thus reducing the need for expensive mechanical stabilization. The method works in several steps, including gyro-based rectification, global alignment using SIFT matching, and a local alignment using KLT tracking. Experimental results are shown but not quantified, as ground truth is, by the nature of the trial, lacking.
  • Willander, Magnus, et al. (författare)
  • UV detectors and LEDs in different metal oxide nanostructures
  • 2014
  • Konferensbidrag (refereegranskat)abstract
    • Different composite nanostructures based pn-junctions have been synthesized using the low temperature hydrothermal chemical growth. The composite nanostructures based pn junctions demonstrated here include p-NiO/n-ZnO, p-CuO/n-ZnO, and p-NiO/n-TiO2. Structural characterization of these composite nanostructures based pn-junctions was performed by different complementary tools and the results indicated that reasonable device quality crystals have been achieved. His act was also confirmed by the rectifying electrical behavior observed from these junctions. Further, the different composite nanostructures based junctions were used to demonstrate UV detectors and visible light emitting diodes (LEDs) operating with acceptable performance.
  • Xu, Tianhua, et al. (författare)
  • Phase noise mitigation in coherent transmission system using a pilot carrier
  • 2011
  • Ingår i: Optical Transmission Systems, Subsystems, and Technologies IX. - SPIE - International Society for Optical Engineering. - 9780819489579
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we investigate the phase noise elimination employing an optical pilot carrier in the high speed coherent transmission system considering the equalization enhanced phase noise (EEPN). The numerical simulations are performed in a 28-Gsymbol/s quadrature phase shift keying (QPSK) coherent system with a polarization multiplexed pilot carrier. The carrier phase estimation is implemented by the one-tap normalized least mean square (NLMS) filter and the differential phase detection, respectively. Simulation results demonstrate that the application of the optical pilot carrier is very effective for the intrinsic laser phase noise cancellation, while is less efficient for the EEPN mitigation.
  • Ahmad, Naeem, et al. (författare)
  • Cost Optimization of a Sky Surveillance Visual Sensor Network
  • 2012
  • Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - Belgium : SPIE - International Society for Optical Engineering. - 978-0-8194-9129-9 ; s. Art. no. 84370U
  • Konferensbidrag (refereegranskat)abstract
    • A Visual Sensor Network (VSN) is a network of spatially distributed cameras. The primary difference between VSN and other type of sensor network is the nature and volume of information. A VSN generally consists of cameras, communication, storage and central computer, where image data from multiple cameras is processed and fused. In this paper, we use optimization techniques to reduce the cost as derived by a model of a VSN to track large birds, such as Golden Eagle, in the sky. The core idea is to divide a given monitoring range of altitudes into a number of sub-ranges of altitudes. The sub-ranges of altitudes are monitored by individual VSNs, VSN1 monitors lower range, VSN2 monitors next higher and so on, such that a minimum cost is used to monitor a given area. The VSNs may use similar or different types of cameras but different optical components, thus, forming a heterogeneous network.  We have calculated the cost required to cover a given area by considering an altitudes range as single element and also by dividing it into sub-ranges. To cover a given area with given altitudes range, with a single VSN requires 694 camera nodes in comparison to dividing this range into sub-ranges of altitudes, which requires only 96 nodes, which is 86% reduction in the cost.
  • Ahmad, Naeem, et al. (författare)
  • Solution space exploration of volumetric surveillance using a general taxonomy
  • 2013
  • Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - 978-081949504-4 ; s. Art. no. 871317
  • Konferensbidrag (refereegranskat)abstract
    • Visual surveillance systems provide real time monitoring of the events or the environment. The availability of low cost sensors and processors has increased the number of possible applications of these kinds of systems. However, designing an optimized visual surveillance system for a given application is a challenging task, which often becomes a unique design task for each system. Moreover, the choice of components for a given surveillance application out of a wide spectrum of available alternatives is not an easy job. In this paper, we propose to use a general surveillance taxonomy as a base to structure the analysis and development of surveillance systems. We demonstrate the proposed taxonomy for designing a volumetric surveillance system for monitoring the movement of eagles in wind parks aiming to avoid their collision with wind mills. The analysis of the problem is performed based on taxonomy and behavioral and implementation models are identified to formulate the solution space for the problem. Moreover, we show that there is a need for generalized volumetric optimization methods for camera deployment.
  • Anders, Åström, et al. (författare)
  • A High Speed 2D Time-to-Impact Algorithm Targeted for Smart Image Sensors
  • 2014
  • Ingår i: Proc. SPIE 9022, Image Sensors and Imaging Systems 2014. - International Society for Optical Engineering; 1999.
  • Konferensbidrag (refereegranskat)abstract
    • In this paper we present a 2D extension of a previously described 1D method for a time-to-impact sensor [5][6]. As in the earlier paper, the approach is based on measuring time instead of the apparent motion of points in the image plane to obtain data similar to the optical flow. The specific properties of the motion field in the time-to-impact application are used, such as using simple feature points which are tracked from frame to frame. Compared to the 1D case, the features will be proportionally fewer which will affect the quality of the estimation. We give a proposal on how to solve this problem. Results obtained are as promising as those obtained from the 1D sensor.
  • Anderson, Sterling J., et al. (författare)
  • Constraint-based semi-autonomy for unmanned ground vehicles using local sensing
  • 2012
  • Ingår i: UNMANNED SYSTEMS TECHNOLOGY XIV. - Bellingham, WA : SPIE - International Society for Optical Engineering. - 978-0-8194-9065-0 ; s. Article no. 83870K
  • Konferensbidrag (refereegranskat)abstract
    • Teleoperated vehicles are playing an increasingly important role in a variety of military functions. While advantageous in many respects over their manned counterparts, these vehicles also pose unique challenges when it comes to safely avoiding obstacles. Not only must operators cope with difficulties inherent to the manned driving task, but they must also perform many of the same functions with a restricted field of view, limited depth perception, potentially disorienting camera viewpoints, and significant time delays. In this work, a constraint-based method for enhancing operator performance by seamlessly coordinating human and controller commands is presented. This method uses onboard LIDAR sensing to identify environmental hazards, designs a collision-free path homotopy traversing that environment, and coordinates the control commands of a driver and an onboard controller to ensure that the vehicle trajectory remains within a safe homotopy. This system's performance is demonstrated via off-road teleoperation of a Kawasaki Mule in an open field among obstacles. In these tests, the system safely avoids collisions and maintains vehicle stability even in the presence of "routine" operator error, loss of operator attention, and complete loss of communications.
  • Andler, Sten F, et al. (författare)
  • SMARTracIn : a concept for spoof resistant tracking of vessels and detection of adverse intentions
  • 2009
  • Ingår i: Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense VIII. - SPIE - International Society for Optical Engineering. - 9780819475718 ; s. 73050G-1-73050G-9
  • Konferensbidrag (refereegranskat)abstract
    • The aim of maritime surveillance systems is to detect threats earlyenough to take appropriate actions. We present the results ofa study on maritime domain awareness performed during the fallof 2008. We analyze an identified capability gap of worldwidesurveillance in the maritime domain, and report from a userworkshop addressing the identified gap. We describe a SMARTracIn conceptsystem that integrates information from surveillance systems with background knowledgeon normal conditions to help users detect and visualize anomaliesin vessel traffic. Land-based systems that cover the coastal watersas well as airborne, space-borne and ships covering open seaare considered. Sensor data are combined with intelligence information fromship reporting systems and databases. We describe how information fusion,anomaly detection and semantic technology can be used to helpusers achieve more detailed maritime domain awareness. Human operators area vital part of this system and should be activecomponents in the fusion process. We focus on the problemof detecting anomalous behavior in ocean-going traffic, and a roomand door segmentation concept to achieve this. This requires theability to identify vessels that enter into areas covered bysensors as well as the use of information management systemsthat allow us to quickly find all relevant information.
  • Becker, Holger, et al. (författare)
  • Microfluidic system for the identification of bacterial pathogens causing urinary tract infections
  • 2015
  • Ingår i: Microfluidics, BioMEMS, and Medical Microsystems XIII. - SPIE - International Society for Optical Engineering. - 978-1-62841-410-3
  • Konferensbidrag (refereegranskat)abstract
    • Urinary tract infections (UTIs) are among the most common bacterial infections and pose a significant healthcare burden. The growing trend in antibiotic resistance makes it mandatory to develop diagnostic kits which allow not only the determination of a pathogen but also the antibiotic resistances. We have developed a microfluidic cartridge which takes a direct urine sample, extracts the DNA, performs an amplification using batch-PCR and flows the sample over a microarray which is printed into a microchannel for fluorescence detection. The cartridge is injection-molded out of COP and contains a set of two-component injection-molded rotary valves to switch between input and to isolate the PCR chamber during thermocycling. The hybridization probes were spotted directly onto a functionalized section of the outlet microchannel. We have been able to successfully perform PCR of E. coli in urine in this chip and perform a fluorescence detection of PCR products. An upgraded design of the cartridge contains the buffers and reagents in blisters stored on the chip.
  • Berrier, Audrey, et al. (författare)
  • Impact of dry-etching induced damage in InP-based photonic crystals
  • 2008
  • Konferensbidrag (refereegranskat)abstract
    • In this work variations of the carrier lifetime in a GaInAsP/InP quantum well in two-dimensional PhC structures etched by Ar/Cl-2 chemically assisted ion beam etching as a function of the processing parameters is investigated. It is shown that the deposition conditions of the SiO2 mask material and its coverage as well as other process steps such as annealing affect the carrier lifetimes. However the impact of patterning the semiconductor on the carrier lifetime is dominant, showing over an order of magnitude reduction. For given PhC lattice parameters, the sidewall damage is shown to be directly related to the measured carrier lifetimes. A simple qualitative model based on sputtering theory and assuming a conical hole-shape development during etching is used to explain the experimental results.
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