Justin A. Hogan

Detection of Leaking CO

Multispectral vegetation reflectance measurements were used as an indirect method of sensing CO2 gas leaking from underground in a controlled release experiment in Bozeman, Montana, USA. The leak location is identified through time-series analysis of the reflectances and the normalized difference vegetation index (NDVI), evaluated at a test location and a control location. Vegetation reflectance changes that correlated with root-level CO2 exposure were distinguishable from changes attributed to seasonal factors including precipitation, wind, air temperature variation, etc. The NDVI of the vegetation became steadily smaller until saturating approximately twenty days after the beginning of the release. However, before reaching the threshold values, both reflectance and NDVI values changed more rapidly when exposed to elevated CO2 fluxes.

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As a component of a multisensor approach to monitoring carbon sequestration sites for possible leaks of the CO₂ gas from underground reservoirs, a low-cost multispectral imaging system has been developed for indirect detection of gas leaks through observations of the resulting stress in overlying vegetation. The imager employs front-end optics designed to provide a full 50° field of view with a small, low-cost CMOS detector, while still maintaining quasi-collimated light through the angle-dependent interference filters used to define the spectral bands. Red and near-infrared vegetation reflectances are used to compute the normalized difference vegetation index (NDVI) and spatial and temporal patterns are analyzed statistically to identify regions of anomalous stress, which are then flagged for closer inspection with in-situ CO₂ sensors. The system is entirely self-contained with an onboard compact computer and is housed in a weather-proof housing to enable extended outdoor deployment.

Gas With Vegetation Reflectances Measured By a Low-Cost Multispectral Imager

Recent research demonstrated that CO2 gas leaking from underground can be identified by observing increased stress in overlying vegetation using spectral imaging. This has been accomplished with both visible/near-infrared (Vis/NIR) sunlight reflection and long-wave infrared (LWIR) thermal emission. During a 4-week period in summer 2011, a controlled CO2release experiment was conducted in Bozeman, Montana, as part of a study of methods for monitoring carbon sequestration facilities. As part of this experiment, reflective and emissive imagers were deployed together to enable a comparison of these two types of imaging systems for vegetation-based CO2 leak detection. A linear regression was performed using time as the response variable with red and NIR reflectances, Normalized Difference Vegetation Index (NDVI), and LWIR brightness temperature as predictors. The regression study showed that the reflectance and LWIR brightness temperature data together explained the most variability in the data (96%), equal to the performance of the Vis/NIR reflectance data alone, followed by NDVI alone (90%), and LWIR data alone (44%). Therefore, the two types of imagers contributed in a synergistic fashion, while either method alone was capable of gas detection with increased statistical variability.

Low-cost multispectral vegetation imaging system for detecting leaking CO 2 gas

A prototype system has demonstrated the capability to use a custom-designed multi-channel sensor to monitor high energy radiation strikes by coupling the silicon sensing elements with a radiation tolerant computer system. The computer system uses triple modular redundant soft processors and custom signal conditioning circuitry to monitor single event effects caused by high energy particles passing through semiconductor materials. The operation of the system was confirmed by exciting the radiation sensing elements with high energy Krypton ions from a cyclotron and monitoring the number of current spikes generated by the generation of electron-hole pairs as the ions lose kinetic energy through collisions within the silicon lattice of the sensors.

Comparison of Long-Wave Infrared Imaging and Visible/Near-Infrared Imaging of Vegetation for Detecting Leaking

Field Programmable Gate Arrays are an attractive platform for reconfigurable computing due to their inherent flexibility and low entry cost relative to custom integrated circuits. With modern programmable devices exploiting the most recent fabrication nodes, designs are able to achieve device-level performance and power efficiency that rivals custom integrated circuits. This paper presents the benchmarking of performance and power efficiency of a variety of standard benchmarks on a Xilinx Virtex-6 75k device using a tiled, partially reconfigurable architecture. The tiled architecture provides the ability to swap in arbitrary processing units in real-time without re-synthesizing the entire design. This has performance advantages by allowing multiple processors and/or hardware accelerators to be brought online as the application requires. This also has power efficiency advantages by keeping unused tiles un-programmed to reduce static power consumption. This paper presents the benchmarking results using a custom Virtex-6 board with a power regulation system that allows instrumentation of each power supply on the Virtex-6 to measure both performance and power efficiency simultaneously.

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This paper presents an analysis of the radiation tolerance of field-programmable gate-array-based space computers. The primary failure mechanism studied in this paper is single-event effects due to...

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Thermal analysis was required in order to aid in the design and testing of a radiation tolerant computing (RTC) system using a radiation sensor. During development of the system, different test beds were employed in order to characterize the radiation sensor and its supporting electronic systems. The most common preliminary tests are high altitude balloon tests which allow the sensor to experience cosmic radiation at high altitudes, consistent with space flight operations. In this study, finite element analysis (FEA) was used to evaluate primary system architecture, system support structures, and the flight payload in order to determine if the system would survive preliminary and future testing. ANSYS FEA software was used to create thermal models which accurately simulated convective cooling, system heat generation, and solar radiation loading on the exterior of the payload. The results of the models were then used to optimize payload PC board (PCB) design to ensure that the internal electronic systems would be within acceptable operating temperatures.

Experimental Conformation of Ionizing Sensing for Space Radiation Environmental Awareness

This paper describes research efforts to mitigate weaknesses in a TMR+spares radiation tolerant SRAM-based FPGA computer system. An existing 9-tile Microblaze architecture is reviewed and the desired improvements of fault-mitigated routing, fault location determination and performance enhancement via runtime-configurable hardware accelerators are discussed. Hamming encoding is proposed as a method for protecting the routing resources from radiation-induced single event upsets and as feedback to the computers configuration control system to distinguish faults occurring in routing from those occurring within partially reconfigurable processing tiles. This is important as the recovery operation for each of these conditions is unique. Without the ability to distinguish routing faults from tile faults, routing faults are aliased as tile faults and unnecessary tile repair steps are taken. In addition to the protected routing with configuration control feedback, architecture for implementing TMR, processor-peripheral hardware accelerators is introduced.

Power efficiency benchmarking of a partially reconfigurable, many-tile system implemented on a Xilinx Virtex-6 FPGA

The Zero Emissions Research and Technology (ZERT) collaborative was formed to address basic science and engineering knowledge gaps relevant to geologic carbon sequestration. The original funding round of ZERT (ZERT I) identified and addressed many of these gaps. ZERT II has focused on specific science and technology areas identified in ZERT I that showed strong promise and needed greater effort to fully develop.

Reliability Analysis of Field-Programmable Gate-Array-Based Space Computer Architectures

This paper describes the benchmarking of an FPGA-based computing system that uses partially reconfigurable tiles for real-time allocation of hardware resources. This system was developed for use in the aerospace industry in order to provide redundancy for fault mitigation and real-time hardware reallocation to reduce mass associated with separate functional systems. In this paper, we present the results of performance studies on our Xilinx Virtex-6 platform using the Dhrystone, LINPACK and NAS-Kernel benchmarks. We further present the impact on power consumption as processors and hardware accelerators are brought online to increase performance.