Relevant bibliographies by topics / GPS degradation

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'GPS degradation'

Author: Grafiati
Published: 4 June 2021
Last updated: 7 February 2022

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Journal articles on the topic "GPS degradation"

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Komarovskiy, Yuriy A. "GPS RECEIVER’S ACCURACY DEGRADATION NEAR TALL OBJECTS." Scholarly Notes of Komsomolsk-na-Amure State Technical University 1, no. 12 (December 30, 2012): 28–35. http://dx.doi.org/10.17084/2012.iv-1(12).5.

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Saeed, Muhammad, Majid Muneer, Muhammad Kaleem Khan Khosa, Nadia Akram, Sheeba Khalid, Muhammad Adeel, Asif Nisar, and Sonia Sherazi. "Azadirachta indica leaves extract assisted green synthesis of Ag-TiO2 for degradation of Methylene blue and Rhodamine B dyes in aqueous medium." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 659–66. http://dx.doi.org/10.1515/gps-2019-0036.

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Abstract Aqueous pollution due to textile industry is an important issue. Photocatalysis is one of the methods used for eradication of dyes from textile industrial effluents. In this study, the synthesis, characterization and evaluation of photo catalytic activity of Ag-TiO2 is reported. TiO2 catalysts with 2, 4, 6 and 8% loading of Ag were prepared by green methods using Azadirachta indica leaves extract as reducing agent with titanium dioxide and silver nitrate as precursor materials. Prepared catalyst was characterized by advanced techniques and was used as catalyst for degradation of Methylene blue and Rhodamine B dyes. Deposition of Ag greatly enhanced the catalytic efficiency of TiO2 towards degradation of dyes. Irradiation of catalyst excites electrons from conduction band of catalyst to valence band yielding an electron-hole pair. This electron-hole pair undergoes secondary reactions and produce OH∙ radicals. These active radicals take part in degradation of dyes. More than 90% dyes were degraded in 120 min. Photo catalytic degradation of Methylene blue and Rhodamine B followed Eley-Rideal mechanism which states that dye react in fluid phase with adsorbed oxygen.
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Afraimovich, E. L., V. V. Demyanov, and T. N. Kondakova. "Degradation of GPS performance in geomagnetically disturbed conditions." GPS Solutions 7, no. 2 (August 1, 2003): 109–19. http://dx.doi.org/10.1007/s10291-003-0053-7.

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Shao, Jia, Kai Deng, Le Chen, Chaomeng Guo, Congshan Zhao, Jiayuan Cui, Tongan Shen, Kewei Li, Jianqiao Liu, and Ce Fu. "Aqueous synthesis of Nb-modified SnO2 quantum dots for efficient photocatalytic degradation of polyethylene for in situ agricultural waste treatment." Green Processing and Synthesis 10, no. 1 (January 1, 2021): 499–506. http://dx.doi.org/10.1515/gps-2021-0046.

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Abstract Low density polyethylene is widely used in agricultural production. It is of low cost and able to significantly improve the quality of fruits. However, its decomposition under natural circumstances needs more than one hundred of years. If not removed in time, it is hazardous to the ecological environment and crops. Up to now, the removal techniques of polyethylene films are polluted, expensive, and difficult to employ. A novel method is proposed for in situ removal of polyethylene by an effective and environmental friendly technique with low cost. The Nb-modified SnO2 quantum dots are prepared for the efficient photocatalytic degradation of polyethylene under visible light. The green synthesis of the photocatalyst includes the procedures of hydrolysis, oxidation, and hydrothermal treatment in aqueous solution. The Nb-modified SnO2 has a band gap of 2.95 eV, which enhances its absorption of visible light. A degradation efficiency of 29% is obtained within 6 h under visible irradiation. The hydroxyl radicals (•OH) are main active species in the degradation process. The prepared Nb-SnO2 quantum dots demonstrate a promising application in the photocatalytic degradation of polyethylene, contributing a novel strategy for the in situ treatment of agricultural wastes.
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Okereke, Olivia I., Dennis J. Selkoe, Michael N. Pollak, Meir J. Stampfer, Frank B. Hu, Susan E. Hankinson, and Francine Grodstein. "A profile of impaired insulin degradation in relation to late-life cognitive decline: A preliminary investigation." International Journal of Geriatric Psychiatry 24, no. 2 (February 2009): 177–82. http://dx.doi.org/10.1002/gps.2089.

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Labhane, Prakash K., Gunvant H. Sonawane, and Shirish H. Sonawane. "Influence of rare-earth metal on the zinc oxide nanostructures: application in the photocatalytic degradation of methylene blue and p-nitro phenol." Green Processing and Synthesis 7, no. 4 (July 26, 2018): 360–71. http://dx.doi.org/10.1515/gps-2017-0006.

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Abstract Rare-earth cerium (Ce)-doped zinc oxide (ZnO) spherical nanoparticles were synthesized by using the co-precipitation method. The doped materials were characterized by means of the X-ray diffraction, Williamson-Hall Plot, and field emission scanning electron microscopy analyses. The prepared nanoparticles exhibit a hexagonal wurtzite structure as observed from the XRD measurements. Energy dispersive X-ray spectroscopy data confirmed the purity of the prepared samples. The photocatalytic activity of the rare-earth Ce-doped ZnO spherical nanoparticles was investigated through the degradation of methylene blue (MB) and p-nitrophenol (PNP) solution under UV light radiation. Among the different amounts of dopant, 5 mole% Ce-doped ZnO nanoparticles showed the highest degradation with UV light radiation for both MB dye and PNP solution. The particle size, morphology, and separation of the photo-induced electron–hole pair are the main factors that influence photocatalytic activity. The probable mechanisms of photocatalytic degradation and mineralization of MB and PNP are also explained by liquid chromatography–mass spectrometry analysis.
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Vinayagam, Ramesh, Thivaharan Varadavenkatesan, and Raja Selvaraj. "Green synthesis, structural characterization, and catalytic activity of silver nanoparticles stabilized with Bridelia retusa leaf extract." Green Processing and Synthesis 7, no. 1 (February 23, 2018): 30–37. http://dx.doi.org/10.1515/gps-2016-0236.

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Abstract:An environmentally benign method to synthesize silver nanoparticles (SNPs) using the leaf extract ofBridelia retusawas developed. The UV-Vis absorption spectrum of the synthesized SNPs displayed a surface plasmon peak at 420 nm. Scanning electron microscopy (SEM) revealed the irregular shaped nanoparticles, and energy dispersive X-ray (EDX) ascertained the presence of metallic silver by showing a strong signal at 3 eV. The crystalline structure of metallic silver was confirmed by X-ray diffraction (XRD). The mean size of the SNPs was calculated as 16.21 nm. Fourier infrared (FT-IR) spectroscopic studies displayed specific bands for various functional groups and affirmed the function of reduction and stabilization of SNPs. The stability was endorsed by the zeta potential value of −18.1 mV. The results evidenced that this leaf extract-mediated synthesis method is eco-friendly, rapid, and cheap. The catalytic power of the SNPs was investigated for Rhodamine B dye degradation. The SNPs completely degraded Rhodamine B within 9 min; thus, the dye degradation process was very rapid. The pseudo-first order degradation constant was found out to be 0.1323 min−1. This paves the way for the future development of novel nano-catalysts to reduce environmental pollution.
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Khue, Do Ngoc, Tran Dai Lam, Dao Duy Hung, Vu Quang Bach, Nguyen Van Anh, Nguyen Hoai Nam, Nguyen Viet Thai, and Do Binh Minh. "Parameters controlling the advanced oxidation degradation kinetics of nitroglycerin and pentaerythritol tetranitrate." Green Processing and Synthesis 7, no. 1 (February 23, 2018): 61–67. http://dx.doi.org/10.1515/gps-2016-0210.

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AbstractSeveral advanced oxidation processes have been performed for the decomposition of ester nitrates (ENs), such as nitroglycerine (NG) and pentaerythritol tetranitrate (PETN). The reaction kinetics for removing NG and PETN by some of the advanced oxidation processes (e.g. UV-H2O2, Fenton, UV-Fenton) followed the pseudo-first-order model. The reaction rates in different systems followed the sequence ENs/UV<ENs/H2O2<ENs/UV-H2O2<ENs/Fenton<ENs/UV-Fenton. The effect of various parameters, such as pH, concentration of hydrogen peroxide, and temperature, on the degradation of NG and PETN were studied.
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Saeed, Muhammad, Nadia Akram, Atta-ul-Haq, Syed Ali Raza Naqvi, Muhammad Usman, Muhammad Amir Abbas, Muhammad Adeel, and Asif Nisar. "Green and eco-friendly synthesis of Co3O4 and Ag-Co3O4: Characterization and photo-catalytic activity." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 382–90. http://dx.doi.org/10.1515/gps-2019-0005.

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Abstract In this study, Co3O4 and Ag-Co3O4 were synthesized by a novel and green method using leaves extract of Helianthus annuus from cobalt nitrate and silver nitrate. The synthesized particles were characterized using X-ray powder diffraction, thermal gravimetric analyses, scanning electron microscopy, particle size analyses and UV-Visible spectroscopy. The photo catalytic activities of synthesized Co3O4 and Ag-Co3O4 were appraised by degrading methyl orange dye and after 120 minutes of reaction a degradation of 53 and 87% was achieved using 100 mg/L (50 mL) solution of methyl orange and 0.1 g Co3O4 and Ag-Co3O4 as catalyst respectively. This green synthesis of Ag-Co3O4 proves to be an eco-benign, environmental benign, simple and effective approach for degradation of dyes in aqueous medium.
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Singh, Jagpreet, Sukhmeen Kaur, Gaganpreet Kaur, Soumen Basu, and Mohit Rawat. "Biogenic ZnO nanoparticles: a study of blueshift of optical band gap and photocatalytic degradation of reactive yellow 186 dye under direct sunlight." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 272–80. http://dx.doi.org/10.1515/gps-2018-0084.

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Abstract Synthesis of nanoparticles (NPs) using plant extracts has been suggested as an environmentally friendly alternative to chemical synthesis of semiconductor NPs. In the present study, ZnO NPs were synthesized by a simple and cost-effective method using Coriandrum sativum leaf extract and zinc acetate as precursors. The as-synthesized ZnO NPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis. The results confirmed the formation of ZnO NPs with a wurtzite structure, spherical shape and average particle size of 24 nm. The photocatalytic degradation of reactive yellow 186 (RY 186) dye was carried out under direct sunlight irradiation and its degradation efficiency and apparent rate constant (K’app) of reaction were calculated to be 93.38%, and 0.0019 min−1, respectively. The optical band gap value of the as-synthesized ZnO NPs was found to be 3.4 eV, which indicates the presence of blueshift. Owing to the presence of blueshift and a wide band gap of synthesized biogenic ZnO NPs, the overall absorption of sunlight irradiation will be enhanced, which leads to higher degradation efficiency of the dye. The current study thus highlights the optical band gap properties of biogenic ZnO NPs and their significance as a heterogeneous catalyst for the purification of polluted water.
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Dissertations / Theses on the topic "GPS degradation"

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Jackson, James Scott. "Enabling Autonomous Operation of Micro Aerial Vehicles Through GPS to GPS-Denied Transitions." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8709.

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Micro aerial vehicles and other autonomous systems have the potential to truly transform life as we know it, however much of the potential of autonomous systems remains unrealized because reliable navigation is still an unsolved problem with significant challenges. This dissertation presents solutions to many aspects of autonomous navigation. First, it presents ROSflight, a software and hardware architure that allows for rapid prototyping and experimentation of autonomy algorithms on MAVs with lightweight, efficient flight control. Next, this dissertation presents improvments to the state-of-the-art in optimal control of quadrotors by utilizing the error-state formulation frequently utilized in state estimation. It is shown that performing optimal control directly over the error-state results in a vastly more computationally efficient system than competing methods while also dealing with the non-vector rotation components of the state in a principled way. In addition, real-time robust flight planning is considered with a method to navigate cluttered, potentially unknown scenarios with real-time obstacle avoidance. Robust state estimation is a critical component to reliable operation, and this dissertation focuses on improving the robustness of visual-inertial state estimation in a filtering framework by extending the state-of-the-art to include better modeling and sensor fusion. Further, this dissertation takes concepts from the visual-inertial estimation community and applies it to tightly-coupled GNSS, visual-inertial state estimation. This method is shown to demonstrate significantly more reliable state estimation than visual-inertial or GNSS-inertial state estimation alone in a hardware experiment through a GNSS-GNSS denied transition flying under a building and back out into open sky. Finally, this dissertation explores a novel method to combine measurements from multiple agents into a coherent map. Traditional approaches to this problem attempt to solve for the position of multiple agents at specific times in their trajectories. This dissertation instead attempts to solve this problem in a relative context, resulting in a much more robust approach that is able to handle much greater intial error than traditional approaches.
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Wheeler, David Orton. "Relative Navigation of Micro Air Vehicles in GPS-Degraded Environments." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6609.

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Most micro air vehicles rely heavily on reliable GPS measurements for proper estimation and control, and therefore struggle in GPS-degraded environments. When GPS is not available, the global position and heading of the vehicle is unobservable. This dissertation establishes the theoretical and practical advantages of a relative navigation framework for MAV navigation in GPS-degraded environments. This dissertation explores how the consistency, accuracy, and stability of current navigation approaches degrade during prolonged GPS dropout and in the presence of heading uncertainty. Relative navigation (RN) is presented as an alternative approach that maintains observability by working with respect to a local coordinate frame. RN is compared with several current estimation approaches in a simulation environment and in hardware experiments. While still subject to global drift, RN is shown to produce consistent state estimates and stable control. Estimating relative states requires unique modifications to current estimation approaches. This dissertation further provides a tutorial exposition of the relative multiplicative extended Kalman filter, presenting how to properly ensure observable state estimation while maintaining consistency. The filter is derived using both inertial and body-fixed state definitions and dynamics. Finally, this dissertation presents a series of prolonged flight tests, demonstrating the effectiveness of the relative navigation approach for autonomous GPS-degraded MAV navigation in varied, unknown environments. The system is shown to utilize a variety of vision sensors, work indoors and outdoors, run in real-time with onboard processing, and not require special tuning for particular sensors or environments. Despite leveraging off-the-shelf sensors and algorithms, the flight tests demonstrate stable front-end performance with low drift. The flight tests also demonstrate the onboard generation of a globally consistent, metric, and localized map by identifying and incorporating loop-closure constraints and intermittent GPS measurements. With this map, mission objectives are shown to be autonomously completed.
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Ellingson, Gary James. "Cooperative Navigation of Fixed-Wing Micro Air Vehicles in GPS-Denied Environments." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8706.

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Micro air vehicles have recently gained popularity due to their potential as autonomous systems. Their future impact, however, will depend in part on how well they can navigate in GPS-denied and GPS-degraded environments. In response to this need, this dissertation investigates a potential solution for GPS-denied operations called relative navigation. The method utilizes keyframe-to-keyframe odometry estimates and their covariances in a global back end that represents the global state as a pose graph. The back end is able to effectively represent nonlinear uncertainties and incorporate opportunistic global constraints. The GPS-denied research community has, for the most part, neglected to consider fixed-wing aircraft. This dissertation enables fixed-wing aircraft to utilize relative navigation by accounting for their sensing requirements. The development of an odometry-like, front-end, EKF-based estimator that utilizes only a monocular camera and an inertial measurement unit is presented. The filter uses the measurement model of the multi-state-constraint Kalman filter and regularly performs relative resets in coordination with keyframe declarations. In addition to the front-end development, a method is provided to account for front-end velocity bias in the back-end optimization. Finally a method is presented for enabling multiple vehicles to improve navigational accuracy by cooperatively sharing information. Modifications to the relative navigation architecture are presented that enable decentralized, cooperative operations amidst temporary communication dropouts. The proposed framework also includes the ability to incorporate inter-vehicle measurements and utilizes a new concept called the coordinated reset, which is necessary for optimizing the cooperative odometry and improving localization. Each contribution is demonstrated through simulation and/or hardware flight testing. Simulation and Monte-Carlo testing is used to show the expected quality of the results. Hardware flight-test results show the front-end estimator performance, several back-end optimization examples, and cooperative GPS-denied operations.
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Harrington, Tomas Seosamh. "Gas diffusion electrodes for environmental applications." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297872.

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Nalin, Laura. "Degradation of environmental protection coatings for gas turbine materials." Thesis, Cranfield University, 2008. http://dspace.lib.cranfield.ac.uk/handle/1826/4522.

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Nowadays, problems of component materials reliability in gas and oil-fired gas turbines focus on assessing the potential behaviour of commonly employed coatings, in order to avoid expensive and unpredictable failure in service and producing new materials whose performance meets life time and manufacturing/ repairing requirements. This MPhil project has investigated the oxidative and corrosive degradation mechanisms for some of the alloy/coatings systems (CMSX-4, CMSX-4/ RT22, CMSX-4/ CN91 and CMSX-4/ “LCO22”), which are currently used for turbines blades and vanes, in order to achieve a better knowledge of materials behaviour and to improve models for the prediction of turbine components’ lives. To achieve this target the study has made use of realistic simulations of turbine exposure conditions in combined with pre- and post-exposure metrology of bar shape materials samples, while optical microscopy has been applied to describe the microstructural evolution during the exposure and the products of the degradation for the hot corrosion. For high temperature oxidation, over extended periods of time (up to 10,000 hours), the research has allowed to describe the morphological changes in respect of the exposure time and temperature and to determine the oxidation kinetics experienced by the alloy and coatings. A model has been presented for predicting θ- α-Al2O3 growth. Moreover, using NASA COSP spalling model, with rate constants values coming from this study, a comparison between experimental mass change data and prediction has been shown. The hot corrosion study has provided new quantitative metal loss data and observations that extend/validate an existing model for materials life prediction, based on defining the severity of the corrosion conditions through measures of gas composition and contaminant deposition flux.
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King, Sarah M. "Enhancement in Degradation of Environmental Pollutants: Fenton Degradation of 2,4,6-Trinitrotoluene and Photodegradation of Deepwater Horizon Crude Oil." ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1451.

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Pollution poses serious threats to both the environmental and the organisms that depend on their environment for survival. Due to the toxicity of most contaminants, there is a dire need for remediation of polluted sites. Remediation studies were conducted on two high priority pollutants: 2,4,6-trinitrotoluene (TNT) and crude oil. TNT was the most common explosive used in the 20th century. Continuous contamination has resulted in an urgent need for remediation. Fenton reagent provides an advanced oxidation process that is capable of remediating recalcitrant explosives, such as TNT. One drawback of Fenton chemistry is that the reaction requires acidic pH to prevent precipitation of iron. Our studies have investigated Fenton degradation of TNT at near neutral pH with several modifiers present: β-cyclodextrin, carboxymethyl-β-cyclodextrin, alcohols, and polyethylene glycol (PEG, MW 200, 400, or 600 g/mol). Fenton degradation was also carried out on other nitroaromatics to better understand the reaction mechanism with PEG 400. Further mechanistic studies investigated the production of nitrate and ammonium with and without PEG 400. The Deepwater Horizon oil spill devastated the Gulf of Mexico and the surrounding wetlands. There are several mechanisms for degradation of oil released into aquatic environments. Bioremediation is one of the most important remediation methods; however degradation becomes stagnant in low nutrient waters. Furthermore, larger molecular weight alkanes and polycyclic aromatic hydrocarbons (PAHs) are not readily available for biodegradation. Transformation of these molecules often requires initial photodegradation. We have investigated the photochemical transformation of oil films with and without photocatalysts present. To better understand the photochemical transformations that occur to the Deepwater Horizon oil, we have conducted additional studies with dispersants present.
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Heath, David John. "Characterisation of waxy gas-condensates by high temperature capillary gas chromatography and oxidative degradation." Thesis, University of Plymouth, 1995. http://hdl.handle.net/10026.1/460.

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High molecular weight (HMW) hydrocarbons (defined herein as C35+ compounds) are difficult to characterise by conventional analytical methods. Very few studies have reported precise and reproducible quantification of such compounds in fossil fuels. Nonetheless, such components have important effects on the physical and biological fate of fossil fuels in the geosphere. For example, the phase behaviour of waxy gas condensates is significantly affected by the varying proportions of HMW compounds. Similarly HMW compounds are amongst the most resistant petroleum components to biodegradation. The current study reports the development of reproducible quantitative high temperature capillary gas chromatography (HTCGC) methods for studying both these aspects of the chemistry of HMW hydrocarbons. In addition those hydrocarbons which remain unresolved when analysed by gas chromatography (so called unresolved complex mixtures UCMs) are also studied. UCMs may account for a large portion of the hydrocarbons in many fossil fuels yet very little is known about their composition. Knowledge of these compounds may be important in enhancing the prediction of phase behaviour. Oxidative degradation and GC-MS is used to elucidate the types of structures present within the UCM. The concentrations of C3S4h. ydrocarbons in two unusually waxy gas condensates from high temperature wells in the North Sea were determined by HTCGC. The whole C, 5+ fraction comprised about 20% of the total hydrocarbons and consisted of compounds with carbon numbers extending up to and beyond Coo. By paying particular attention to sample dissolution and injection, good reproducibility and precision were obtained. For example, for authentic n-C, to n-C60 alkanes a relative standard deviation of under 5% for manual injection, linear response factors (1.01 Cm to 0.99 C6), and a linear calibration for 5 ng to 25 ng on-column were found. Limits of detection are reported for the first time for HMW n-alkanes. The limits were found to be as low as 0.8 ng for Cto to 1.87 ng for C60. Tristearin is proposed as a suitable HTCGC internal standard for quantification since the FID response factor (1.1) was close to that of the HMW n-alkanes and response was linear. Importantly, when co-injected with the two waxy North Sea condensates, tristearin was adequately separated from the closest eluting alkanes, n-C59 and n-C60 under normal operating conditions. Qualitative characterisation of the HMW compounds in the waxy gas condensates and in synthetic wax blends (polywax 1000) using HTCGC-EI MS and HTCGC-CI MS produced molecular ions or pseudo molecular ions for n-alkanes up to n- C6o. The spectra of some HMW compounds contained fragment ions characteristic of branched compounds but detailed characterisation was very limited. This study has also shown, for the first time, the significance of the unresolved complex mixture in gas condensatesU. CM hydrocarbonsa ccountedf or over 20% of the total hydrocarbons in a waxy North sea condensateT. he condensatew as first distilled and the distillate UCMs isolated. Thesew ere found to be between 64 to 97 % unresolved after molecular sieving (5A) and urea adduction. The UCMs were oxidised using CrO3/AcOHw hich produced5 -12% C02, and 55-83% dichloromethane-solublep roducts. Thus 65-94% of the original UCMs were accounted for as oxidation products. The remainder were thought to be water soluble acids which could not be determined in the presence of the AcOH reagent. Of the recovered oxidised products, 27- 81 % were resolved and these comprised mainly n-monocarboxylic acids (19-48 %). The average chain length was found to be C12 indicating the average length of alkyl groups. Branched acids, ketones, ketoacids, ndicarboxylic acids, branched dicarboxylic acids, lactones, isoprenoid acids, alkylcyclohexane carboxylic acids and toluic acids accounted for the majority of the remaining resolved products. The distillate UCMs all showed variations in amountso f productsb ut not in composition. Retro-structurala nalysis suggestedth at the UCM in the gasc ondensatew as mainly aliphatic and branched.T he numbero f isomerso f simple brancheda lkaneso ver the UCM molecular weight range (determined by cryoscopy) was calculated to be over 15000. Overall, oxidation provided structural information for about half of the UCM. HTCGC was also used to measure the biodegradability of HMW alkanes in a waxy Indonesian oil. Traditional alkane isolation techniques (TLC and CC) discriminated against HMW compounds above C40 whereas adsorption onto alumina in a warm cyclohexane slurry provided an aliphatic fraction still rich in HMW compounds and suitable as a biodegradation substrate. A waxy Indonesian oil was subjected to 136 day biodegradation by Pseudomonas fluorescens. Extraction efficiencies of over 90 % (RSD <5 %) were obtained for n-alkanes up to C6o using continuous liquid-liquid extraction. Over 80 % of the oil aliphatic fraction was degraded within 14 days. After 136 days only 14% of the original aliphatic fraction remained, yet surprisingly no decreases in the concentrations of compounds above C45 were observed. However, the use of a rapid screening biodegradation method proved conclusively that Pseudomonasfluorescens was capable of utilising n-alkanes up to C60 once the bacteria had acclimated to the HMW alkanes. This is the first report of bacterial utilisation of an n-alkane as large as C.
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Lawrence, Bryce T. "Recreation related degradation in Kansas state parks : applying GIS models." Thesis, Manhattan, Kan. : Kansas State University, 2005. http://hdl.handle.net/2097/74.

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Morgenstern, Anne. "Thermokarst and thermal erosion : degradation of Siberian ice-rich permafrost." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2012/6207/.

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Current climate warming is affecting arctic regions at a faster rate than the rest of the world. This has profound effects on permafrost that underlies most of the arctic land area. Permafrost thawing can lead to the liberation of considerable amounts of greenhouse gases as well as to significant changes in the geomorphology, hydrology, and ecology of the corresponding landscapes, which may in turn act as a positive feedback to the climate system. Vast areas of the east Siberian lowlands, which are underlain by permafrost of the Yedoma-type Ice Complex, are particularly sensitive to climate warming because of the high ice content of these permafrost deposits. Thermokarst and thermal erosion are two major types of permafrost degradation in periglacial landscapes. The associated landforms are prominent indicators of climate-induced environmental variations on the regional scale. Thermokarst lakes and basins (alasses) as well as thermo-erosional valleys are widely distributed in the coastal lowlands adjacent to the Laptev Sea. This thesis investigates the spatial distribution and morphometric properties of these degradational features to reconstruct their evolutionary conditions during the Holocene and to deduce information on the potential impact of future permafrost degradation under the projected climate warming. The methodological approach is a combination of remote sensing, geoinformation, and field investigations, which integrates analyses on local to regional spatial scales. Thermokarst and thermal erosion have affected the study region to a great extent. In the Ice Complex area of the Lena River Delta, thermokarst basins cover a much larger area than do present thermokarst lakes on Yedoma uplands (20.0 and 2.2 %, respectively), which indicates that the conditions for large-area thermokarst development were more suitable in the past. This is supported by the reconstruction of the development of an individual alas in the Lena River Delta, which reveals a prolonged phase of high thermokarst activity since the Pleistocene/Holocene transition that created a large and deep basin. After the drainage of the primary thermokarst lake during the mid-Holocene, permafrost aggradation and degradation have occurred in parallel and in shorter alternating stages within the alas, resulting in a complex thermokarst landscape. Though more dynamic than during the first phase, late Holocene thermokarst activity in the alas was not capable of degrading large portions of Pleistocene Ice Complex deposits and substantially altering the Yedoma relief. Further thermokarst development in existing alasses is restricted to thin layers of Holocene ice-rich alas sediments, because the Ice Complex deposits underneath the large primary thermokarst lakes have thawed completely and the underlying deposits are ice-poor fluvial sands. Thermokarst processes on undisturbed Yedoma uplands have the highest impact on the alteration of Ice Complex deposits, but will be limited to smaller areal extents in the future because of the reduced availability of large undisturbed upland surfaces with poor drainage. On Kurungnakh Island in the central Lena River Delta, the area of Yedoma uplands available for future thermokarst development amounts to only 33.7 %. The increasing proximity of newly developing thermokarst lakes on Yedoma uplands to existing degradational features and other topographic lows decreases the possibility for thermokarst lakes to reach large sizes before drainage occurs. Drainage of thermokarst lakes due to thermal erosion is common in the study region, but thermo-erosional valleys also provide water to thermokarst lakes and alasses. Besides these direct hydrological interactions between thermokarst and thermal erosion on the local scale, an interdependence between both processes exists on the regional scale. A regional analysis of extensive networks of thermo-erosional valleys in three lowland regions of the Laptev Sea with a total study area of 5,800 km² found that these features are more common in areas with higher slopes and relief gradients, whereas thermokarst development is more pronounced in flat lowlands with lower relief gradients. The combined results of this thesis highlight the need for comprehensive analyses of both, thermokarst and thermal erosion, in order to assess past and future impacts and feedbacks of the degradation of ice-rich permafrost on hydrology and climate of a certain region.
Die gegenwärtige Klimaerwärmung wirkt sich auf arktische Regionen stärker aus als auf andere Gebiete der Erde. Das hat weitreichende Konsequenzen für Permafrost, der weite Teile der terrestrischen Arktis unterlagert. Das Tauen von Permafrost kann zur Freisetzung erheblicher Mengen an Treibhausgasen sowie zu gravierenden Änderungen in der Geomorphologie, Hydrologie und Ökologie betroffener Landschaften führen, was wiederum als positive Rückkopplung auf das Klimasystem wirken kann. Ausgedehnte Gebiete der ostsibirischen Tiefländer, die mit Permafrost des Yedoma Eiskomplex unterlagert sind, gelten aufgrund des hohen Eisgehalts dieser Permafrostablagerungen als besonders empfindlich gegenüber Klimaerwärmungen. Thermokarst und Thermoerosion sind zwei Hauptformen der Permafrostdegradation in periglazialen Landschaften. Die zugehörigen Landschaftsformen sind auf der regionalen Skala bedeutende Indikatoren klimainduzierter Umweltvariationen. Thermokarstseen und senken (Alasse) sowie Thermoerosionstäler sind in den Küstentiefländern der Laptewsee weit verbreitet. Die vorliegende Dissertation untersucht die räumliche Verbreitung und die morphometrischen Eigenschaften dieser Degradationsformen mit dem Ziel, ihre Entwicklungsbedingungen während des Holozäns zu rekonstruieren und Hinweise auf potenzielle Auswirkungen zukünftiger Permafrostdegradation im Zuge der erwarteten Klimaerwärmung abzuleiten. Der methodische Ansatz ist eine Kombination aus Fernerkundungs-, Geoinformations- und Geländeuntersuchungen, die Analysen auf lokalen bis regionalen räumlichen Skalen integriert. Thermokarst und Thermoerosion haben die Untersuchungsregion tiefgreifend geprägt. Im Eiskomplexgebiet des Lena-Deltas nehmen Thermokarstsenken eine weitaus größere Fläche ein als Thermokarstseen auf Yedoma-Hochflächen (20,0 bzw. 2,2 %), was darauf hin deutet, dass die Bedingungen für die Entwicklung von großflächigem Thermokarst in der Vergangenheit wesentlich günstiger waren als heute. Die Rekonstruktion der Entwicklung eines einzelnen Alas im Lena-Delta belegt eine andauernde Phase hoher Thermokarstaktivität seit dem Übergang vom Pleistozän zum Holozän, die zur Entstehung einer großen und tiefen Senke führte. Nach der Drainage des primären Thermokarstsees im mittleren Holozän erfolgten Permafrostaggradation und degradation parallel und in kürzeren abwechselnden Etappen innerhalb des Alas und führten zu einer komplexen Thermokarstlandschaft. Trotzdem die spätholozäne Thermokarstentwicklung im Alas dynamischer ablief als die erste Entwicklungsphase, resultierte sie nicht in der Degradation großer Teile pleistozäner Eiskomplexablagerungen und einer wesentlichen Veränderung des Yedoma-Reliefs. Weitere Thermokarstentwicklung in bestehenden Alassen ist begrenzt auf geringmächtige Lagen holozäner eisreicher Alas-Sedimente, da die Eiskomplexablagerungen unter den großen primären Thermokarstseen vollständig getaut waren und die unterlagernden Sedimente aus eisarmen, fluvialen Sanden bestehen. Thermokarstprozesse auf ungestörten Yedoma-Hochflächen wirken am stärksten verändernd auf Eiskomplexablagerungen, werden aber in Zukunft auf geringere Ausmaße begrenzt sein, da die Verfügbarkeit großer ungestörter, schwach drainierter Yedoma-Hochflächen abnimmt. Auf der Insel Kurungnakh im zentralen Lena-Delta beträgt der für zukünftige Thermokarstentwicklung verfügbare Anteil an Yedoma-Hochflächen nur 33,7 %. Die zunehmende Nähe von sich entwickelnden Thermokarstseen auf Yedoma-Hochflächen zu bestehenden Degradationsstrukturen und anderen negativen Reliefformen verringert die Möglichkeit der Thermokarstseen, große Ausmaße zu erreichen bevor sie drainieren. Die Drainage von Thermokarstseen durch Thermoerosion ist in der Untersuchungsregion weit verbreitet, aber Thermoerosionstäler versorgen Thermokarstseen und –senken auch mit Wasser. Neben diesen direkten hydrologischen Wechselwirkungen zwischen Thermokarst und Thermoerosion auf der lokalen Ebene existiert auch eine Interdependenz zwischen beiden Prozessen auf der regionalen Ebene. Eine regionale Analyse weitreichender Netze von Thermoerosionstälern in drei Tieflandgebieten der Laptewsee mit einer Fläche von insgesamt 5800 km² zeigte, dass diese Formen häufiger in Gebieten mit höheren Geländeneigungen und Reliefgradienten auftreten, während Thermokarstentwicklung stärker in flachen Tiefländern mit geringeren Reliefgradienten ausgeprägt ist. Die kombinierten Ergebnisse dieser Dissertation zeigen die Notwendigkeit von umfassenden Analysen beider Prozesse und Landschaftsformen, Thermokarst und Thermoerosion, im Hinblick auf die Abschätzung vergangener und zukünftiger Auswirkungen der Degradation eisreichen Permafrosts auf Hydrologie und Klima der betrachteten Region und deren Rückkopplungen.
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Al-Hussein, Salem. "GIS modelling of land degradation in northern Jordan using satellite imagery." Thesis, University of Leicester, 2000. http://hdl.handle.net/2381/30386.

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Northern Jordan has undergone tremendous land cover change during the last three decades. This study tried to answer the following question: How have population growth and socio-economic influences affected soil quality in northern Jordan? The underlying factors that have led to the changes in land use and land cover are poorly documented, but efforts in this area started to be effective with the creation of the Badia Research and Development Programme. However, there has been little effort to spatially correlate the land cover changes with soil quality. An empirical model based on high resolution spatial and temporal remotely sensed data offers the ability to assess the degradation impacts of changes in land cover in a spatial context. In an attempt to assess the impacts of changing land cover on soil, a GIS-based erosion model has been developed to predict annual soil loss by water in northern Jordan. This model uses the Revised Universal Soil Loss Equation (RUSLE). Spatially distributed static (topographic and soil) parameters for this model are extracted from a regional GIS developed specifically for the Badia Programme area. The dynamic (vegetation cover) parameter is estimated from the land cover maps, derived by digital processing of multi-resolution, multi temporal Landsat MSS (14.9. 1972, 16. 7. 1985) and TM (28. 8. 1992). Mapping of vegetation cover was carried out by applying TM-Linear Mixture Modelling and NDVI, while mapping of fallow lands was carried out by both on-screen digitizing and sketch mapping in the field. The image difference technique was used in the change detection analysis. The erosion model predicts an increase in the amount of soil loss in the study area from 1972 to 1992, as a result of land cover changes. It was concluded that the degradation of the soil in the study area, observed during the last two decades, was caused by effects of these land cover changes.
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Books on the topic "GPS degradation"

1

Gana, Ngah. The smelling gas: A radio play about environmental degradation. Bamenda [Cameroon]: N. Gana, 1996.

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Deichmann, Uwe. Global digital datasets for land degradation studies: A GIS approach. Nairobi: Global Environment Monitoring System, United Nations Environment Programme, 1991.

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Doherty, Faith. Burma: Human lives for natural resources, oil & natural gas. [Bangkok?: Southeast Asian Information Network and All Burma Students' Democratic Front, 1994.

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Sharakas, Othman. Land degradation risk assessment in the Palestinian Central Mountains utilizing remote sensing and GIS techniques. Bergen: BRIC, 2007.

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100 ways to save the world. Chichester, West Sussex: Bonnier Books, 2007.

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author, Singh Vishal, and Centre for Ecology Development and Research (Dehra Dūn, India), eds. Carbon trading and co-benefits: Opportunities in the central Himalaya (Uttarakhand). Dehra Dun, India: Centre for Ecology Development and Research, 2014.

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Center for International Forestry Research, ed. Moving ahead with REDD: Issues, options and implications. Bogor Barat, Indonesia: Center for International Forestry Research, 2008.

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International Union for Conservation of Nature and Natural Resources, ed. Legal frameworks for REDD: Design and implementation at the national level. Gland, Switzerland: IUCN, 2009.

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Pact, Asia Indigenous Peoples. What is REDD?: A guide for indigenous communities. [Chiang Mai, Thailand?]: Asia Indigenous Peoples Pact (AIPP), Forest Peoples Programme (FPP), International Work Group for Indigenous Affairs (IWGIA), Tebtebba, 2010.

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Dharmawan, I. Wayan Susi. Enhanced approaches to estimate net emission reductions from deforestation and degradation of undrained peat swamp forests in Central Kalimantan, Indonesia. Bogor, West Java, Indonesia: Center for Climate Change and Policy Research and Development, Forestry Research and Development Agency, Ministry of Forestry, Indonesia in cooperation with International Tropical Timber Organization (ITTO), 2013.

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Book chapters on the topic "GPS degradation"

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Coster, Anthea J., and Endawoke Yizengaw. "GNSS/GPS Degradation from Space Weather." In Space Weather Effects and Applications, 165–81. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2021. http://dx.doi.org/10.1002/9781119815570.ch8.

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Abeyratne, Ruwantissa. "Vulnerabilities of the Air Transportation System to Loss or Degradation of the GPS Signal." In Air Navigation Law, 235–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25835-0_13.

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Brandt, Wolf F., and Gerhard Frank. "Manual Gas Phase Isothiocyanate Degradation." In Methods in Protein Sequence Analysis, 52–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73834-0_8.

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Mair, Georg W. "Strength Degradation and Lifetime Assessment." In Safety Assessment of Composite Cylinders for Gas Storage by Statistical Methods, 151–242. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-49710-5_4.

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Jung, Jine Sung, S. Y. Chang, Keun Bong Yoo, Gee Wook Song, Min Sung Kang, and M. T. Kim. "Degradation Evaluation of the Gas Turbine Hot-Gas-Path Component." In Key Engineering Materials, 2266–71. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-978-4.2266.

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Tynybekov, Azamat. "Glacier Degradation from GIS and Remote Sensing Data." In Use of Satellite and In-Situ Data to Improve Sustainability, 159–63. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9618-0_18.

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Kimoto, S., F. Oka, Y. Miki, T. Fukuda, and H. Iwai. "A Chemo-Thermo-Mechanically Coupled Behavior During Gas Hydrate Dissociation and Its Numerical Analysis." In Advances in Bifurcation and Degradation in Geomaterials, 85–91. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1421-2_11.

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Krechkovska, Halyna, Myroslava Hredil, and Oleksandra Student. "Structural and Fractographic Features of Gas Pipeline Steel Degradation." In Lecture Notes in Civil Engineering, 45–59. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58073-5_4.

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Okubo, H., S. Watanabe, N. Hayakawa, and T. Kumai. "Insulation Degradation Mechanism of Epoxy Spacer Samples for GIS." In Gaseous Dielectrics X, 353–60. Boston, MA: Springer US, 2004. http://dx.doi.org/10.1007/978-1-4419-8979-6_48.

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Belalla, Skender, Ilir Salillari, Adrian Doko, Fran Gjoka, and Majlinda Cenameri. "Content of Heavy Metals in Albanian Soils and Determination of Spatial Structures Using GIS." In Land Degradation and Desertification: Assessment, Mitigation and Remediation, 389–400. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-8657-0_30.

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Conference papers on the topic "GPS degradation"

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Wesson, Kyle D., Swen D. Ericson, Terence L. Johnson, Karl W. Shallberg, Per K. Enge, Louis K. Dressel, and Christopher J. Hegarty. "GPS Receiver Performance Degradation in the Presence of Faded Interference." In 2016 International Technical Meeting of The Institute of Navigation. Institute of Navigation, 2016. http://dx.doi.org/10.33012/2016.13391.

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Khan, Faisal Ahmed, and Andrew G. Dempster. "Effects on CDMA network performance due to degradation of GPS based synchronization." In 2007 International Symposium on Communications and Information Technologies. IEEE, 2007. http://dx.doi.org/10.1109/iscit.2007.4392073.

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Kulkarni, Chetan S., Gautam Biswas, Xenofon Koutsoukos, Jose Celaya, and Kai Goebel. "Diagnostic/Prognostic Experiments for Capacitor Degradation and Health Monitoring in DC-DC Converters." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3862.

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Studying and analyzing the ageing mechanisms of electronic components avionics in systems such as the GPS and INAV are of critical importance. In DC-DC power converter systems electrolytic capacitors and MOSFET’s have higher failure rates among the components. Degradation in the capacitors under varying operating conditions leads to high ripples output voltages and currents affecting downstream components leading to cascading faults. For example, in avionics systems where the power supply drives a GPS unit, ripple currents can cause glitches in the GPS position and velocity output, and this may cause errors in the Inertial Navigation (INAV) system, causing the aircraft to fly off course The work in this paper proposes a detail experimental and systematic study on analyzing the degradation phenomenon is electrolytic capacitors under high stress operating conditions. The output degradation is typically measured by an increase in ESR (Equivalent Series Resistance) and decrease in the capacitance value. We present the details of our accelerated ageing methodology along with analysis and comparison of the results.
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Sikirica, Nenad, Franc Dimc, Oliver Jukic, Teodor B. Iliev, Darko Spoljar, and Renato Filjar. "A Risk Assessment of Geomagnetic Conditions Impact on GPS Positioning Accuracy Degradation in Tropical Regions Using Dst Index." In 2021 International Technical Meeting of The Institute of Navigation. Institute of Navigation, 2021. http://dx.doi.org/10.33012/2021.17852.

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Pulinets, Sergey A., Dmitry V. Davidenko, Andrzej W. Krankowski, and Manuel Hernandez-Pajares. "The physical background and GPS TEC processing technology for identification of ionospheric anomalies forming over seismically active zones and leading to GNSS signals degradation." In 2015 1st URSI Atlantic Radio Science Conference (URSI AT-RASC). IEEE, 2015. http://dx.doi.org/10.1109/ursi-at-rasc.2015.7303135.

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Caridad, Jose, Arthur Watson, Song Shang, Eric Nguyen, and Gocha Chochua. "Gas Purging System to Extend Thrust Bearing Life in ESPs." In SPE Gulf Coast Section Electric Submersible Pumps Symposium. SPE, 2021. http://dx.doi.org/10.2118/204482-ms.

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Abstract Electric submersible pump (ESP) systems use thrust bearings in the seal section to handle the thrust generated by the pump stages. Thrust bearings are subjected to harsh operating conditions, including high loads, poor oil circulation, and motor oil viscosity degradation. A less-recognized issue is gas becoming centrifugally trapped under the thrust runner. The gas may be present because of incomplete purging of air during filling, permeation of well gas into the motor oil, or gradual gasification of motor oil at high temperatures. Because thrust bearings are such critical components, it is of interest to increase their reliability, which in turn will increase ESP life. A novel gas purging system (GPS) was designed to alleviate stressors on thrust bearings, including gas accumulation, viscosity deterioration and gasification at high temperature, and low working oil volume. GPS circulates oil along with any gas that accumulates under the thrust runner up to a quiet separation chamber. Degassed oil circulates back to the thrust bearing, while accumulated gas eventually purges to the wellbore through relief valves on subsequent on/off cycles. GPS also improves viscosity and reduces gasification by cooling the oil, and it provides a greater working volume of thrust bearing oil to reduce the effects of oil deterioration. This paper details the GPS design principles as well as the optimization of the different design parameters that affect its performance conducted via computational fluid dynamics (CFD). Observations captured on a test fixture built using the final configuration are also presented, validating the intended functionality.
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Botros, K. K., C. Hartloper, H. Golshan, and D. Rogers. "Assessment of Recoverable vs Unrecoverable Degradations of Gas Turbines Employed in Five Natural Gas Compressor Stations." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42078.

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Gas Turbines (GT), like other prime movers, experience wear and tear over time, resulting in decreases in available power and efficiency. Further decreases in power and efficiency can result from erosion and fouling caused by the airborne impurities the engine breathes in. To counteract these decreases in power and efficiency, it is standard procedure to ‘wash’ the engine from time to time. In compressor stations on gas transmission systems, engine washes are performed off-line and are scheduled in such intervals to optimize the maintenance procedure. This optimization requires accurate prediction of the performance degradation of the engine over time. A previous paper demonstrated a methodology for evaluating various components of the GT gas path, in particular the air compressor side of the engine since it is most prone to fouling and degradation. This methodology combines Gas Path Analysis (GPA) to evaluate the thermodynamic parameters over the engine cycle followed by parameter estimation based on the Bayesian Error-in-Variable Model (EVM) to filter the data of possible noise due to measurement errors. The methodology quantifies the engine-performance degradation over time, and indicates the effectiveness of each engine wash. In the present paper, the methodology was extended to assess both recoverable and un-recoverable degradations of five gas turbine engines employed on TransCanada’s pipeline system in Canada. These engines are: three GE LM2500+, one RR RB211-24G, and one GE LM1600 gas turbines. Hourly data were collected over the past four years, and engine health parameters were extracted to delineate the respective engine degradations. The impacts of engine loading, site air quality conditions and site elevation on engine-air-compressor isentropic efficiency are compared between the five engines.
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Suleiman, Suleiman M., and Yi-Guang Li. "Application of Artificial Neural Network Based Gas Path Diagnostics on Gas Pipeline Compressors." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15062.

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Abstract This paper presents the development of an artificial neural network (ANN) Gas Path Diagnostics (GPD) technique applied to pipeline compression system for fault detection and quantification. The work detailed the various degradation mechanisms and the effect of such degradations on the performance of natural gas compressors. The data used in demonstrating the ANN diagnostics is so derived using an advanced thermodynamic performance simulation model of integrated pipeline and compressor systems, which has embedded empirical compressor map data and pipeline resistance model. Implantation of faults within the model is in such a way to account for faults degradations caused by fouling, erosion and corrosion, of various degrees of severities, to obtain wide range of corresponding simulated “true” measurements. In order to account for uncertainties normally encountered in field measurements, Gaussian noise distribution was combined with simulated true measurements, which depends on the instrument’s tolerances. Furthermore, since judicious measurements selection are crucial in ensuring flawless GPD predictions, a sensitivity and correlation analysis of the available measurements revealed that discharge temperature, rotational speed and torque are the most effective measurements for the diagnostics with acceptable degrees of accuracies. The measurements observability technique is a novel approach in pipeline compressor diagnostics. Analytical case studies of the developed method show that, a selected ANN architecture can detect and quantify faults related to degradation in efficiency and flow capacities in the presence of instrument error, varied operational and environmental conditions.
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Itoh, Nobunari, Masahiro Katoh, and Nobuaki Okano. "Comparison of spectral transmittance degradation due to organic gas contamination with on-orbit degradations of launched sensors." In Asia-Pacific Remote Sensing, edited by Allen M. Larar, Mervyn J. Lynch, and Makoto Suzuki. SPIE, 2008. http://dx.doi.org/10.1117/12.804917.

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Hanachi, Houman, Jie Liu, Avisekh Banerjee, Ying Chen, and Ashok Koul. "A Physics-Based Performance Indicator for Gas Turbine Engines Under Variable Operating Conditions." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26367.

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Gas turbines are often used under variable ambient conditions and power demands, which also may be off their design points. Such operating scenarios affect the typical performance parameters, such as thermal efficiency, mass flow and power. As a result, such parameters may fail to accurately indicate the structural degradation of a gas turbine. The objective of this study is to develop a robust physics-based performance indicator for a gas turbine to demonstrate the short term recoverable as well as long term non-recoverable degradation level of the engine, independent of the operating conditions. A comprehensive physics-based thermodynamic model for the gas path of a single shaft gas turbine is developed to accurately predict the cycle parameters based on limited actual operating data. Consequently, for the given ambient condition, demanded power and shaft speed, the model predicts the cycle parameters for the gas turbine in a healthy condition as the baseline. In reality, the measured parameters gradually deviate from the model, which reflects the performance deterioration of the engine caused by degradation mechanisms. In order to capture this performance deterioration, the ratio of the excess exhaust heat power with respect to the design point power, called Excess Heat Ratio (EH) is being proposed as an effective indicator. The effectiveness of the Excess Heat Ratio is examined by using 38-month operating data of an industrial gas turbine between two major overhauls. The trends of EH clearly shows its capability to capture the short term recoverable degradations and subsequent retrievals, arising from compressor fouling and subsequent wash. In addition, EH is also able to capture the trend of the long term non-recoverable degradations. The proposed indicator has the following advantages: 1) only limited data from the operating system of a gas turbine is required without the need of additional instrumentation; 2) the both short and long term degradations of the gas turbine can be quantified by a single indicator that is independent from the operating conditions; and 3) it is practically applicable for real-time monitoring and maintenance planning.
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Reports on the topic "GPS degradation"

1

Richard N. Wright. Kinetics of Gas Reactions and Environmental Degradation in NGNP Helium. Office of Scientific and Technical Information (OSTI), June 2006. http://dx.doi.org/10.2172/911710.

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Reed, D. T., J. Hoh, J. Emery, S. Okajima, and T. Krause. Gas production due to alpha particle degradation of polyethylene and polyvinylchloride. Office of Scientific and Technical Information (OSTI), July 1998. http://dx.doi.org/10.2172/303944.

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Gleeson, Brian. Degradation of TBC Systems in Environments Relevant to Advanced Gas Turbines for IGCC Systems. Office of Scientific and Technical Information (OSTI), September 2014. http://dx.doi.org/10.2172/1179177.

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Harrison, Kale Warren, Dustin Murtagh, Humberto Silva, and Joseph Gabriel Cordaro. Thermal Degradation Investigation of Polyurethane Elastomers using Thermal Gravimetric Analysis - Gas Chromatography/Mass Spectrometry. Office of Scientific and Technical Information (OSTI), January 2017. http://dx.doi.org/10.2172/1505419.

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Krentz, T., and D. Hitchcock. 2019 ACCOMPLISHMENTS - DEGRADATION OF MECHANICAL PROPERTIES IN STRUCTURAL METALS AND WELDS FOR GTS RESERVOIRS. Office of Scientific and Technical Information (OSTI), January 2020. http://dx.doi.org/10.2172/1596925.

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Singh, D., N. Chen, C. Lorenzo-Martin, J. L. Routbort, K. Pagilla, M. Urgan-Demirtas, K. Reddy, et al. Study on degradation of a commercial rigid polyurethane foam used for fillingof process gas equipment. Office of Scientific and Technical Information (OSTI), August 2006. http://dx.doi.org/10.2172/895663.

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Ronevich, Joseph Allen, Dorian K. Balch, Christopher W. San Marchi, Scott West, and Mike Morgan. SNL/SRNL Joint Project on degradation of mechanical properties in structural metals and welds for GTS reservoirs. Office of Scientific and Technical Information (OSTI), December 2015. http://dx.doi.org/10.2172/1234814.

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Ronevich, Joseph Allen, Christopher W. San Marchi, Dorian K. Balch, and Michael Morgan. SNL/SRNL Joint Project on degradation of mechanical properties in structural metals and welds for GTS reservoirs. Office of Scientific and Technical Information (OSTI), January 2017. http://dx.doi.org/10.2172/1505402.

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Smith, Jonell, Michael White, Robert Bernstein, and James Hochrein. Identification of volatile butyl rubber thermal-oxidative degradation products by cryofocusing gas chromatography/mass spectrometry (cryo-GC/MS). Office of Scientific and Technical Information (OSTI), February 2013. http://dx.doi.org/10.2172/1093689.

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10

Fan, Li, and Veronica Mendizabal Joffre. The Gender Dimension of Sustainable Consumption and Production: A Microsurvey-Based Analysis of Gender Differences in Awareness, Attitudes, and Behaviors in the People’s Republic of China. Asian Development Bank, December 2020. http://dx.doi.org/10.22617/wps200401-2.

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Abstract:
Using microsurveys conducted in the People’s Republic of China over the past 2 decades, this paper explores the individual preferences among men and women toward sustainable consumption and production—the concept of doing more with less and decoupling economic growth from environmental degradation. The study finds that women exhibit greener living and working habits than men. However, women—regardless of education, rural–urban setting, or age—are impacted by time poverty, low political participation, limited awareness, gender norms, and, for younger and older women, financial limitations. To encourage and increase women’s capacity in shaping environmental solutions, economic and political gender gaps must be addressed and awareness on the impact of consumption needs to be strengthened.
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