Journal articles: '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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Mohan, Santhanam, and Manickam Vishnu Devan. "Photocatalytic activity of Ag/Ni bi-metallic nanoparticles on textile dye removal." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 895–900. http://dx.doi.org/10.1515/gps-2019-0060.

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Abstract The photocatalysis of Ag/Ni bi-metallic nano-particles on safranin O dye degradation was evaluated by UV light irradiations. Ag/Ni bi-metallic nanoparticles were synthesized by the green approach using Zingiber officinale root (Zinger) extract. The average particles size of Ag/Ni bi-metallic nanoparticles was found to be 70-88 nm from SEM image and from XRD patterns it was confirmed that the existence of Ag/Ni bi-metallic nano-particles. 8 mg of Ag/Ni bi-metallic nanoparticles present in 40 mL of 10 ppm dye, degraded completely in presence of UV light irradiations within 30 min time durations. The effect of dye degradation within a short period of time (30 min) was due to wide band gap energy and photochemical redox reactions.

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Atia, Mohamed Maher, Tashfeen Karamat, and Aboelmagd Noureldin. "An Enhanced 3D Multi-Sensor Integrated Navigation System for Land-Vehicles." Journal of Navigation 67, no. 4 (March 12, 2014): 651–71. http://dx.doi.org/10.1017/s0373463314000083.

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In urban areas, Global Positioning System (GPS) accuracy deteriorates due to signal degradation and multipath effects. To provide accurate and robust navigation in such GPS-denied environments, multi-sensor integrated navigation systems are developed. This paper introduces a 3D multi-sensor navigation system that integrates inertial sensors, odometry and GPS for land-vehicle navigation. A new error model is developed and an efficient loosely coupled closed-loop Kalman Filter (Extended KF or EKF) integration scheme is proposed. In this EKF-based integration scheme, the inertial/odometry navigation output is continuously corrected by EKF-estimated errors, which keeps the errors within acceptable linearization ranges which improves the prediction accuracy of the linearized dynamic error model. Consequently, the overall performance of the integrated system is improved. Real road experiments and comparison with earlier works have demonstrated a more reliable performance during GPS signal degradation and accurate estimation of inertial sensor errors (biases) have led to a more sustainable performance reliability during long GPS complete outages.

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Jaffri, Shaan Bibi, and Khuram Shahzad Ahmad. "Foliar-mediated Ag:ZnO nanophotocatalysts: green synthesis, characterization, pollutants degradation, and in vitro biocidal activity." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 172–82. http://dx.doi.org/10.1515/gps-2018-0058.

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Abstract A green, biomimetic, and one-pot synthesis of silver-doped zinc oxide (ZnO:Ag) nanoparticles via hydrothermal route utilizing Prunus cerasifera leaf extract has been reported for the first time. Synthetic route involved optimization for leaf extract. Doped nanoparticles were characterized for crystalline, optical, compositional, and morphological makeup via X-ray diffraction (XRD), ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. Direct energy bandgap was calculated through Tauc plot. The incorporation of Ag+ into Zn2+ sites within ZnO crystal was obtained using leaf extract as a reducing agent. Ag inculcated positional modifications in ZnO structure confirmed via XRD-shifted peaks. Ag:ZnO nanoparticles were found to be an efficient nanophotocatalyst against bromocresol green and bromophenol blue (R2=0.83 and 0.95, respectively) in direct solar irradiance. Degradation efficiencies up to 86% and 95% in less than 15min were achieved. Furthermore, the synthesized doped nanoparticles expressed highly active to active zones of inhibition against nine microbes of pathogenic nature toward human and crops. Doped nanoparticles inhibitory activity was found to exceed standard antibiotic drugs ampicillin and amphotericin B in a standard Kirby-Bauer disc diffusion assay. Creditable photocatalytic and antimicrobial activities of synthesized doped nanoparticles signify their prospects in commercialization into nanophotocatalyst and bactericidal/fungicidal agent at industrial scale.

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Tran, Tan Duc, and Thuy Phu Nguyen. "ACCURACY ENHANCEMENT OF A LOW COST INS/GPS INTEGRATION SYSTEM FOR LAND APPLICATIONS." Science and Technology Development Journal 12, no. 4 (February 28, 2009): 30–38. http://dx.doi.org/10.32508/stdj.v12i4.2229.

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In this paper, the design of the low cost INS/GPS integration system is addressed with good accuracy. The Strapdown INS (SINS) and Cascade Kalman filter have been tested to ensure that the system can be operated flexibly between feed forward and feedback modes due to various GPS conditions. The vehicle motion constraints are also utilized to reduce the INS error degradation during the periods of GPS unavailability. The experiment results shown that the INS/GPS system can be applied to land applications in challenging GPS environments.

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Wang, Jau-Hsiung, and Yang Gao. "High-Sensitivity GPS Data Classification Based on Signal Degradation Conditions." IEEE Transactions on Vehicular Technology 56, no. 2 (March 2007): 566–74. http://dx.doi.org/10.1109/tvt.2007.891492.

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Ali, Imran, Changsheng Peng, Dichu Lin, and Iffat Naz. "Green synthesis of the innovative super paramagnetic nanoparticles from the leaves extract of Fraxinus chinensis Roxb and their application for the decolourisation of toxic dyes." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 256–71. http://dx.doi.org/10.1515/gps-2018-0078.

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Abstract The leaves extract of Fraxinus chinensis Roxb was used for the synthesis of the innovative phytogenic magnetic nanoparticles (PMNPs) without adding toxic surfactants. The formation, morphology, elemental composition, size, thermal stability, structure and magnetic properties of these PMNPs were examined by UV-visible spectrophotometry, FT-IR, XRD, SEM, EDX, TEM, VSM, XPS, BET and TGA. The reactivity of the obtained PMNPs against decolourising toxic dyes, namely, malachite green (MG), crystal violet (CV) and methylene blue (MB), were investigated by UV-vis spectrophotometry. Further, the factors affecting the removal of dyes, including solution pH, adsorbent dosages, initial concentration of dyes, reaction temperature and contact time, were also investigated. The results revealed the decolourisation of 99.12% of MG and 98.23% of CV within 60 min, and 97.52% of MB within 200 min by the PMNPs using dyes concentration of 25 mg/l at pH 6.5 and 298.15 K. The kinetics outcome indicated that the degradation of dyes matched well to the pseudo first-order reaction kinetics model. Furthermore, the probable degradation mechanism of dyes by the PMNPs, including the adsorption of cationic dye molecules onto the negatively charged surface of adsorbent and the oxidation of the Fe° in the solution, were discussed. Thus, the PMNPs can be produced by the bulk and have great potential to be employed for biomedical/environmental remediation.

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Ferguson, Dale C., Ryan C. Hoffmann, Daniel P. Engelhart, and Elena A. Plis. "Voltage Threshold and Power Degradation Rate for GPS Solar Array Arcing." IEEE Transactions on Plasma Science 45, no. 8 (August 2017): 1972–75. http://dx.doi.org/10.1109/tps.2017.2694387.

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Cong, Li, Haidong Wang, Honglei Qin, and Luqi Liu. "An Environmentally-Adaptive Positioning Method Based on Integration of GPS/DTMB/FM." Sensors 18, no. 12 (December 6, 2018): 4292. http://dx.doi.org/10.3390/s18124292.

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The Global Positioning System (GPS) yields good precision and availability in open outdoor environment. However, the errors of GPS may suffer degradation in some complex environments, such as forests and urban canyons. To solve this problem, a new positioning method is designed integrating GPS, Digital Terrestrial Multimedia Broadcast (DTMB) and frequency-modulated (FM) radio signal. In this method, the DTMB transmitter acts as a pseudo-satellite to assist GPS positioning. Furthermore, the FM fingerprint positioning is used to correct the positioning bias. An adaptive selection scheme is proposed to provide an optimal integration mode of the sensors. Field experiments in complex environment were carried out for evaluation. Comparing to the GPS-only and GPS + DTMB approach, positioning accuracy was improved by at least 68.21 % and 21.27 % with the proposed method, respectively.

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Ren, Qinhui, Fuhua Wei, Hongliang Chen, Ding Chen, and Bo Ding. "Preparation of Zn-MOFs by microwave-assisted ball milling for removal of tetracycline hydrochloride and Congo red from wastewater." Green Processing and Synthesis 10, no. 1 (January 1, 2021): 125–33. http://dx.doi.org/10.1515/gps-2021-0020.

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Abstract In this study, we prepared Zn-MOFs as an ordinary, low-cost, and efficiency method taking advantage of zinc(ii) acetate monohydrate and 1,3,5-benzenetricarboxylic acid in microwave-assisted ball milling. The Zn-MOFs were measured via scanning electron microscopy, infrared spectrometry, X-ray diffraction, and thermogravimetry. We explored its use as a photocatalyst for the degradation of tetracycline hydrochloride and Congo red from aqueous solutions. The results demonstrate that the kinetic model was appropriate for the removal of organic pollutants. In general, it is feasible, inexpensive, and effective to use metal organic framework (MOF) to treat waste liquid. Therefore, our findings indicate that Zn-MOFs have broad application vista in wastewater purification.

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Lahuta, Lesław B., and Joanna Goszczyńska. "Inhibition of raffinose family oligosaccharides and galactosyl pinitols breakdown delays germination of winter vetch (Vicia villosa Roth.) seeds." Acta Societatis Botanicorum Poloniae 78, no. 3 (2011): 203–8. http://dx.doi.org/10.5586/asbp.2009.025.

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Beside RFOs, which are commonly present in legume seeds, seeds of some species contain galactosyl pinitols (GPs). These carbohydrates, like RFOs, have been hypothesized to constitute an important energy and carbon skeletal source during germination. To test this hypothesis we have applied a specific α-galactosidase inhibitor (1-deoxygalactonojirimycin, DGJ) to germinating winter vetch (<em>Vicia villosa</em> Roth.) seeds, containing more galactosyl pinitols than RFOs. The breakdown of RFOs but not that of GPs was completely blocked in both embryonic axes and cotyledons tissues, during the first 18 h of imbibition in DGJ. The inhibitor only decreased the rate of GPs degradation. The inhibitory effect of DGJ on GPs degradation was partially alleviated by addition of sucrose or galactose to DGJ solutions. After three days of germination in water, RFOs and GPs disappeared in axial tissues of seeds imbibed in water, galactose or sucrose. Eighteen-hour imbibition of seeds in DGJ drastically reduced germination, by ca 50%, during the first three days. The inhibitory effect of DGJ decreased during the next seven days of germination. The presence of galactose or sucrose in imbibition solution initially stimulated seed germination, but later this effect was not statistically significant. Our study provides clear evidence that galactosyl pinitols play an important role in early winter vetch seeds germination. Additionally, we suggest that galactosyl pinitols can replace RFOs as reserve material necessary for early germination.

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Anjum, Farhana, Saima Gul, Mohammad Iqbal Khan, and Murad Ali Khan. "Efficient synthesis of palladium nanoparticles using guar gum as stabilizer and their applications as catalyst in reduction reactions and degradation of azo dyes." Green Processing and Synthesis 9, no. 1 (December 24, 2019): 63–76. http://dx.doi.org/10.1515/gps-2020-0008.

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AbstractPalladium is very expensive metal and has numerous applications especially as a versatile hydrogenation and dehydrogenation catalyst for chemical reactions. The main hurdle in its wide use is the high materials cost. In the present study a cost effective palladium nano catalyst was prepared using the green method of synthesis with guar gum as capping and reducing agent. The formations of palladium nanoparticles were confirmed by UV-spectrophotometer while for morphology and nature, SEM and XRD were performed that confirmed the crystalline nature of PdNPs and proved the roughly spherical shape of nanoparticles. FT-IR analysis showed different functional groups of reducing agent and proved that guar gum have the ability to stabilized as well as to reduce the Pd (II) to Pd (0). Specific signal for the palladium is present in EDX spectra that further confirmed the formation of PdNPs. The catalytic efficiency was studied using the hydrogenation of 4-nitrophenol. Rate constant of prepared nano-catalyst was 0.1436/min, its efficiency, TON, TOF, in above mention reaction is 90.83, 27.78, and 185.2/hrs, respectively. Data obtained proved synthesized PdNPs to be efficient heterogeneous catalyst for the reduction of 4-NP and for the degradation of azo dyes.

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Bi, Zhihao, Zhihao Li, and Lifeng Yan. "Catalytic oxidation of lignin to dicarboxylic acid over the CuFeS2 nanoparticle catalyst." Green Processing and Synthesis 7, no. 4 (July 26, 2018): 306–15. http://dx.doi.org/10.1515/gps-2017-0056.

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AbstractCuFeS2nanoparticles have been synthesized and used as catalyst for the degradation of lignin. Under mild condition of reaction at 60°C and 5 h in the presence of 2 ml hydrogen peroxide, lignin can be degraded completely and converted to dicarboxylic acids, such as oxalic acid (OA), fumaric acid, maleic acid, and succinic acid (SA), carbon oxides, and aromatic compounds. The major product is OA (up to 30% selectivity) and SA. On the basis of the chemicals detected, we proposed a logical mechanism similar to Fenton reaction. The results reveal that HO˙ and HOO−, formed from the cleavage of hydrogen peroxide over the catalyst, play an essential role in the oxidation of lignin to destroy its aromatic structure and generate carboxylic or DCA. This is a potential method to convert native lignin as a renewable feedstock to produce valuable chemicals.

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Rahmani, Ehasn, and Mohammad Rahmani. "Denitrification of water using ZnO/Cu as the photocatalyst." Green Processing and Synthesis 7, no. 3 (June 27, 2018): 255–59. http://dx.doi.org/10.1515/gps-2016-0221.

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Abstract The ZnO:xCu photocatalyst was prepared with reacting media, namely, water method followed by wet impregnation to deposit Cu on the ZnO nano particles. X-ray diffraction was used to perform crystallography and the determination of the ZnO:xCu particle size. Fourier transform infrared was employed for the detection of chemical bonds in the synthesized photocatalyst. The nanoparticle morphology was studied by field emission scanning electron microscope. The elemental composition of the synthesized catalysts was evaluated with X-ray fluorescence technique. Diffuse reflection spectroscopy analysis was performed to investigate the light absorption of the ZnO:xCu catalysts. The photocatalytic activity of the prepared ZnO:xCu nanoparticles was studied for the removal of nitrate from the aqueous solution of ammonium nitrate (50 mg·l−1) under UV irradiation. Results indicated that the ZnO:xCu photocatalyst has high photocalytic activity to remove nitrate from water. Moreover, complete degradation was achieved after 2.5 h.

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Pińkowska, Hanna, Małgorzata Krzywonos, Paweł Wolak, and Adrianna Złocińska. "Production of uronic acids by hydrothermolysis of pectin as a model substance for plant biomass waste." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 683–90. http://dx.doi.org/10.1515/gps-2019-0039.

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Abstract The hydrolysis of high methyl ester citrus-apple pectin as a model substance for plant biomass waste rich in pectin fraction resulting in an uronic acids was performed in a batch reactor using subcritical water. The effects of the reaction temperature and time on the composition of the products contained in the separated liquid fractions were studied. The optimal experimental design methodology was used for modelling and optimizing the yield of uronic acids. In good agreement with experimental results (R2 = 0.986), the model predicts an optimal yield of uronic acids (approx. 77.3 g kg-1 ± 0.7 g kg-1) at a temperature and a time of about 155°C and 36 min. Uronic acids were isolated from reaction mixture using the ion exchange method. Higher temperature and longer holding time resulted in a greater degree of thermal degradation of uronic acids and simultaneously higher yield of losses and gas fractions

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Thi Thuong, Nghiem, Phan Trung Nghia, and Seiichi Kawahara. "Factors influencing green strength of commercial natural rubber." Green Processing and Synthesis 7, no. 5 (October 25, 2018): 399–403. http://dx.doi.org/10.1515/gps-2018-0019.

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Abstract The factors influencing the green strength of commercial solid rubbers were investigated in the present study through characterization of commercial natural rubber (NR). Various solid commercial rubbers such as standard Vietnam rubber (SVR10), standard Indonesia rubber (SIR10), India standard natural rubber (ISNR10), ribbed smoked sheets (RSS3), and FNR (commercial Sumitomo Rubber) were used as a source. Purification of the samples was carried out through acetone extraction and purified samples were characterized by nuclear magnetic resonance (NMR) and Fourier-Transform infrared spectroscopy. Degradation was found for SVR10, ISNR10, and SIR10 but not for RSS3 and FNR through the assignment of 13C-NMR signals. Acetone extraction was found to improve the green strength of commercial NR due to the removal of impurities. Linked fatty acids and proteins contributed to the upturn of stress at small strain. However, the network structure of degraded rubbers had an insignificant role in enhancing the green strength of commercial NR.

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Li, Xin, Jiming Guo, and Lv Zhou. "Performance analysis of BDS/GPS kinematic vehicle positioning in various observation conditions." Sensor Review 36, no. 3 (June 20, 2016): 249–56. http://dx.doi.org/10.1108/sr-12-2015-0198.

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Purpose Global positioning system (GPS) kinematic positioning suffers from performance degradation in constrained environments such as urban canyons, which then restricts the application of high-precision vehicle positioning and navigation within the city. In December 2012, the BeiDou Navigation Satellite System (BDS) regional service was announced, and the combined BDS/GPS kinematic positioning has been enabled in the Asia-Pacific area. Previous studies have mainly focused on the performance evaluations of combined BDS/GPS static positioning. Not much work has been performed for kinematic vehicle positioning under constrained observation conditions. This study aims to analyze the performance of BDS/GPS kinematic vehicle positioning in various conditions. Design/methodology/approach In this study, three vehicle experiments under three observation conditions, an open suburban area, a less dense non-central urban area and a dense central urban area, are investigated using both the code-based differential global navigation satellite system (DGNSS) and phase-based real-time kinematic (RTK) modes. The comparison between combined BDS/GPS and GPS-only vehicle positioning solutions is conducted in terms of positioning availability and positioning precision. Findings Numerical results show that the combined BDS/GPS system significantly outperforms the GPS-only system under poor observation conditions, whereas the improvement was less significant under good observation conditions. Originality/value Thus, this paper studies the performance of combined BDS/GPS kinematic relative positioning under various observation conditions.

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Willigen, Durk Van. "Eurofix." Journal of Navigation 42, no. 3 (September 1989): 375–81. http://dx.doi.org/10.1017/s0373463300014661.

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Around 1992 Navstar/GPS will become fully operational. Public access is then provided in the Standard Precision Service, SPS, at a reduced accuracy of 100 metres for 95 per cent of the fixes. The exclusively US military-operated system and the deliberately introduced degradation (SA, selective availability) of the attainable accuracy have some drawbacks for European navigation. Neither the probability density function of the error amplitude, nor its power spectral density function is known. So, using Navstar/GPS as a sole-means precise and reliable navigational aid for high-risk transports is not possible.

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Elghamrawy, Haidy, Malek Karaim, Mohamed Tamazin, and Aboelmaged Noureldin. "Experimental Evaluation of the Impact of Different Types of Jamming Signals on Commercial GNSS Receivers." Applied Sciences 10, no. 12 (June 20, 2020): 4240. http://dx.doi.org/10.3390/app10124240.

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The received global navigation satellite system (GNSS) signal has a very low power due to traveling a very long distance and to the nature of the signal’s propagation medium. Thus, GNSS signals are easily susceptible to signal interference. Signal interference can cause severe degradation or interruption in GNSS position, navigation, and timing (PNT) services which could be very critical, especially in safety-critical applications. The objective of this paper is to evaluate the impact of the presence of jamming signals on a high-end GNSS receiver and investigate the benefits of using a multi-constellation system under such circumstances. Several jamming signals are considered in this research, including narrowband and wideband signals that are located on GPS L1 or GLONASS L1 frequency bands. Quasi-real dynamic trajectories are generated using the Spirent™ GSS6700 GNSS signal simulator combined with an interference signal generator through a Spirent™ GSS8366 unit. The performance evaluation was carried out using several evaluation metrics, including signal power degradation, navigation solution availability, dilution of precision (DOP), and positioning accuracy. The multi-constellation system presented better performance over the global positioning system (GPS)-only constellation in most cases. Moreover, jamming the GPS band caused more critical effects than jamming the GLONASS band.

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Wang, Xueyun, Kui Li, Pengyu Gao, and Wei Wang. "Reinforced Ultra-Tightly Coupled GPS/INS System for Challenging Environment." Mathematical Problems in Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/609154.

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Among all integration levels currently available for Global Positioning System (GPS) and Inertial Navigation System (INS) Integrated System, ultra-tightly coupled (UTC) GPS/INS system is the best choice for accurate and reliable navigation. Nevertheless the performance of UTC GPS/INS system degrades in challenging environments, such as jamming, changing noise of GPS signals, and high dynamic maneuvers. When low-end Inertial Measurement Units (IMUs) based on MEMS sensors are employed, the performance degradation will be more severe. To solve this problem, a reinforced UTC GPS/INS system is proposed. Two techniques are adopted to deal with jamming and high dynamics. Firstly, adaptive integration Kalman filter (IKF) based on fuzzy logics is developed to reinforce the antijamming ability. The parameters of membership functions (MFs) are adjusted and optimized through self-developed neutral network. Secondly, a Doppler frequency error estimator based on Kalman filter is designed to improve the navigation performance under high dynamics. A complete simulation platform is established to evaluate the reinforced system. Results demonstrate that the proposed system architecture significantly improves navigation performance in challenging environments and it is a more advanced solution to accurate and reliable navigation than traditional UTC GPS/INS system.

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Zhang, Wu. "Preparation of the anatase phase TiO2 nanocrystallites using subcritical water as the solvent and evaluation of their photocatalytic properties under visible light irradiation." Green Processing and Synthesis 7, no. 6 (November 27, 2018): 506–14. http://dx.doi.org/10.1515/gps-2017-0157.

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Abstract Anatase phase TiO2 nanocrystallites are prepared using subcritical water and Rhodamine B (RB) as the solvent and the model pollutant, respectively, to test the photocatalytic activity of the obtained TiO2 nanocrystallites. The experimental results indicate that the prepared products exhibit better photocatalytic properties than those of commercial P25. The sample characterization results also indicate that the anatase phase TiO2 nanocrystallites are generated in the hydrolysis process and that the crystallinity is remarkably increased after calcination. The crystallite sizes of the anatase nanocrystallites are investigated and the interactions between the factors are evaluated using response surface methodology. The optimal conditions for the preparation process are obtained as follows: hydrolysis temperature of 603 K, calcination temperature of 953 K, calcination time of 60 min and solution pressure of 13 MPa. The practical experiments under the optimal condition are carried out in triplicate, and the average crystallite size is 21.38 nm. The photodegradation kinetics is discussed using the Langmuir-Hinshelwood (LH) model. The results show that LH model is feasible in describing RB degradation.

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Chiaradia, Ana Paula Marins, Hélio Koiti Kuga, and Bruna Yukiko Pinheiro Lopes Masago. "Satellite Orbit Determination Using Short Arcs of GPS Data." Applied Mechanics and Materials 706 (December 2014): 206–21. http://dx.doi.org/10.4028/www.scientific.net/amm.706.206.

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This work is concerned with short arcs orbit determination using GPS signals. A special case of truncated arcs assuming that GPS data is only available when the satellite carrying the GPS receiver passes over a ground tracking station is presented. The behaviour of an Extended Kalman filter (EKF) in real time satellite orbit determination using short arcs of data is analysed. The algorithm is a simplified and compact model with low computational cost, and uses the EKF to estimate the state vector, composed of position and velocity components, and GPS receiver clock parameters. The algorithm may use different step-sizes between the GPS signal measurements. Its force model in the motion equations considered the perturbations as being due to the geopotential up to the 10thorder and degree of the spherical harmonics. The algorithm has been formerly qualified using raw single frequency pseudorange GPS measurements of the Topex/Poseidon (T/P) satellite, and used as reference in this work. However, the GPS data are truncated as if they had been collected by a single ground tracking station. In other words, the data are obtained only when the satellite T/P is within the viewing area of the station. The research results are presented showing the degradation of performance when compared to a full arc orbit determination.

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Liu, C. J. "Effects of Selective Availability on GPS Positioning Accuracy." Southern Journal of Applied Forestry 26, no. 3 (August 1, 2002): 140–45. http://dx.doi.org/10.1093/sjaf/26.3.140.

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Abstract Deactivation of selective availability (SA) is expected to provide improvement in Global Positioning System (GPS) accuracy, and recent reports showed such improvements were realized immediately. However, most forestry GPS observations are made in subcanopy environments in which a GPS receiver's antenna can only receive GPS signals from a small region of the sky due to obstructions. Consequently, the satellite geometry will be poor, and position accuracy will suffer. Thus, there is a need to understand the impact of SA removal on positioning accuracy in high-PDOP subcanopy observations. This study found that it is difficult to approach the destination when GPS navigation is adversely influenced by SA accuracy degradation. When GPS positioning is performed after SA deactivation, a GPS observer can walk directly to the intended destination under thick tree canopies. Results also indicated that the horizontal accuracy is 73.3 m at the 95% probability level in the SA-degraded data set and 8.3 m in the SA-free data set. Further data analysis indicated that HDOPs (Langley 1999) recorded in the SA-on and the SA-off periods are not statistically significantly different. This suggests that a major portion of the difference in horizontal accuracies between SA-degraded and SA-free GPS observations can be attributed to difficulties in approaching the destination when SA is active. South. J. Appl. For. 26(3):140–145.

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Jaworski, Sławomir, Barbara Strojny, Ewa Sawosz, Mateusz Wierzbicki, Marta Grodzik, Marta Kutwin, Karolina Daniluk, and André Chwalibog. "Degradation of Mitochondria and Oxidative Stress as the Main Mechanism of Toxicity of Pristine Graphene on U87 Glioblastoma Cells and Tumors and HS-5 Cells." International Journal of Molecular Sciences 20, no. 3 (February 2, 2019): 650. http://dx.doi.org/10.3390/ijms20030650.

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Due to the development of nanotechnologies, graphene and graphene-based nanomaterials have attracted immense scientific interest owing to their extraordinary properties. Graphene can be used in many fields, including biomedicine. To date, little is known about the impact graphene may have on human health in the case of intentional exposure. The present study was carried out on U87 glioma cells and non-cancer HS-5 cell lines as in vitro model and U87 tumors cultured on chicken embryo chorioallantoic membrane as in vivo model, on which the effects of pristine graphene platelets (GPs) were evaluated. The investigation consisted of structural analysis of GPs using transmission electron microscopy, Fourier transmission infrared measurements, zeta potential measurements, evaluation of cell morphology, assessment of cell viability, investigation of reactive oxygen species production, and investigation of mitochondrial membrane potential. The toxicity of U87 glioma tumors was evaluated by calculating the weight and volume of tumors and performing analyses of the ultrastructure, histology, and protein expression. The in vitro results indicate that GPs have dose-dependent cytotoxicity via ROS overproduction and depletion of the mitochondrial membrane potential. The mass and volume of tumors were reduced in vivo after injection of GPs. Additionally, the level of apoptotic and necrotic markers increased in GPs-treated tumors.

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Jiménez, F., J. E. Naranjo, F. García, and J. M. Armingol. "Can Low-Cost Road Vehicles Positioning Systems Fulfil Accuracy Specifications of New ADAS Applications?" Journal of Navigation 64, no. 2 (March 2, 2011): 251–64. http://dx.doi.org/10.1017/s0373463310000470.

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Some new Advanced Driver Assistance Systems (ADAS) need on-the-lane vehicle positioning on accurate digital maps, but current applications of vehicle positioning do not justify the surcharge of very accurate equipment such as DGPS or high-cost inertial systems. For this reason, the performance of GPS in autonomous mode is analyzed. Although satisfactory results can be found, in some areas the GPS signal is lost or degraded so it is necessary to know the positioning error when using only inertial system data. A theoretical approach based on the uncertainty propagation law is used to estimate the upper limit of distance that can be travelled fulfilling the specifications of an assistance system. Test results support the conclusions of this approach. Finally, the combination of GPS and inertial systems is studied, with the conclusion that the theoretical approach is valid when inertial measurements are used right from the start of GPS signal degradation, without waiting for a complete loss of signal.

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Morikawa, Claudio Kendi. "A new green approach to Fenton’s chemistry using tea dregs and coffee grounds as raw material." Green Processing and Synthesis 3, no. 2 (April 1, 2014): 117–25. http://dx.doi.org/10.1515/gps-2013-0113.

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Abstract Fenton’s chemistry has long been useful in industry because of the power of hydrogen peroxide (HP), in the presence of ferrous iron (Fe2+), to produce a highly reactive free radical species capable of oxidizing aqueous materials. However, its application has been limited due to the rapid oxidation of ferrous iron. The rapid oxidation of ferrous iron limits the production of free radicals necessary for a powerful reaction. We developed two ‘green’ iron catalysts using used tea leaves (tea dregs) or coffee grounds as raw material. The new ‘green’ iron catalysts contained iron in a reductive stable status for a Fenton catalyst. The study showed that the developed ‘green’ iron catalysts can be used as iron fertilizer and for the Fenton’s reaction on the degradation of methylene blue (MB), and in the disinfection of Escherichia coli. The tea and coffee polyphenols were estimated to be responsible for the reductive stable state of the iron in the developed catalysts, due to their reducing power and chelating iron ability. The developed new ‘green’ iron catalysts are expected to diffuse in wide fields such as food, medicine, public health, agriculture, the environment, etc.

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Khan, Shahid Ali, Muhammad Ismail, Yasir Anwar, Aliya Farooq, Bassam Oudh Al Johny, Kalsoom Akhtar, Zafar Ali Shah, et al. "A highly efficient and multifunctional biomass supporting Ag, Ni, and Cu nanoparticles through wetness impregnation for environmental remediation." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 309–19. http://dx.doi.org/10.1515/gps-2018-0101.

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Abstract Plant-based materials are reported to have a wide range of applications in the environmental and biomedical sectors. In this report, we present an economic and environmentally friendly supported turmeric powder (TP) biomass for the support of Ag, Ni and Cu nanoparticles (NPs) designated as Ag@TP, Ni@TP and Cu@TP. The in situ syntheses of the stated NPs were achieved in aqueous medium using NaBH4 as a reducing agent. The prepared NPs were applied for the degradation of o-nitrophenol (ONP), m-nitrophenol (MNP), p-nitrophenol (PNP), methyl orange (MO), Congo red (CR), rhodamine B (RB) and methylene blue (MB). Initially, Ag@TP, Ni@TP and Cu@TP were screened for the MO dye and antibacterial activity, where Ag@TP displayed the strongest catalytic activity for MO and bactericidal activities as compared to Ni@TP and Cu@TP. The quantity of metal ions adsorbed onto the TP was investigated by atomic absorption spectroscopy. The Ag@TP, Ni@TP and Cu@TP were characterized through X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM) analysis.

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Shah, Luqman, Hani S. H. Mohammed Ali, Bello Aminu Bello, Shahid Ali Khan, Yasir Anwar, Muhammad Sharjeel Javed Khan, Khalid Ms Alghamdi, and Sher Bahadar Khan. "Catalytic performance of the biosynthesized AgNps from Bistorta amplexicaule: antifungal, bactericidal, and reduction of carcinogenic 4-nitrophenol." Green Processing and Synthesis 9, no. 1 (June 5, 2020): 259–67. http://dx.doi.org/10.1515/gps-2020-0027.

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AbstractThis study was focused to synthesize silver nanoparticles (AgNps) from the aqueous extract of Bistorta amplexicaule and to evaluate their antimicrobial, antifungal, and 4-nitrophenol (4-NP) degradation potential. The AgNps from B. amplexicaule were characterized by field emission scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy studies. The biological activity of the AgNps was checked against the three bacterial and two fungal strains. The inhibition activities of the synthesized nanoparticles on pathogenic bacteria and fungi were equally studied using the colony-forming unit method. The AgNps synthesized showed excellent bactericidal and fungicidal activities against pathogenic Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans, and Candida tropicalis. The removal of nitrophenols is one of the most demanding tasks, due to their injurious impact on the health of the living organisms. The AgNps showed superior performance compared with the pure plant extract. The AgNps also displayed efficient catalytic ability in reducing toxic 4-NP into harmless 4-aminophenol in the presence of NaBH4 solution. Hence, the synthesized AgNps can be effectively used against bacterial and fungal infections and in the decontamination of 4-NP polluted water.

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Hussain, Shah, Hani S. H. Mohammed Ali, Shahid Ali Khan, Aliya Farooq, Najla bint Saud Al-Saud, Yasir Anwar, Abdullah M. Asiri, Zia Ur Rahman, Noor ul Amin, and Sher Bahadar Khan. "Synthesis of biomass-supported CuNi zero-valent nanoparticles through wetness co-impregnation method for the removal of carcinogenic dyes and nitroarene." Green Processing and Synthesis 9, no. 1 (April 29, 2020): 237–47. http://dx.doi.org/10.1515/gps-2020-0028.

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AbstractStabilization of zero-valent CuNi nanoparticles (NPs) supported on Cicer arietenum (CP) is reported here for the reduction and removal of persistent organic pollutants. The functional groups and interactions of NPs with the CP were determined by ATR-FTIR. The crystallinity, morphology, and the elemental composition of the samples were determined through powder XRD, FESEM, and EDS techniques, respectively. The XRD spectrum displayed a sharp crystalline peak at 43.9 for CuNi. The Cu and Ni zero-valent NPs displayed a peak at almost the same region, and thus, both the peaks are merged and appeared as a single peak. The chemical reduction/degradation of eight model pollutants, viz., 2-nitrophenol (ONP), 3-nitrophenol (MNP), 4-nitrophenol (PNP), 2,4-dinitrophenol (DNP), methyl orange (MO), congo red (CR), methylene blue (MB), and rhodamine B (RB) were carried out in the presence of NaBH4. The kapp value of 0.1 mM 4NP was highest which was 1.8 × 10−1 min−1 while the slowest rate was observed for CR and RB with kapp 5.5 × 10−3 and 5.4 × 10−3 min−1 respectively. This article helps in the removal of toxic organic pollutants through green supported NPs.

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Catchpole, Ivan, Peter Upton, Andrew Sinclair, and Jim Nagle. "Wide Area Differential GPS Field Study." Journal of Navigation 47, no. 2 (May 1994): 146–58. http://dx.doi.org/10.1017/s0373463300012066.

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Inmarsat commissioned the field study to be carried out by Signal Computing Ltd. in association with the Royal Greenwich Observatory. The study aimed to identify the commercial suitability of Wide Area Differential GPS (WADGPS) corrections. The corrections provided to users will be relayed via Inmarsat-3 geostationary satellites and are required to be valid over the footprint of an entire Inmarsat ocean region (approximately one third of the Earth's surface).The study has been conducted within the Inmarsat Atlantic Ocean Region East. Trials took place over a five-month period to achieve a representative set of data. Six widely-distributed collection sites were used to ensure that the maximum duration of satellite data were received and that a representative model for atmospheric effects was obtained. Analysis is restricted to the use of GPS carrier and phase data obtained using the C/A code transmitted by Block II satellites only.This paper presents the analysis of data collected during a four-day trial period. The ability to determine the GPS satellite ephemeris (independent of GPS broadcast ephemeris), Klobuchar model parameters tailored to the oceanic region, and satellite clock corrections using GPS data obtained from this limited deployment of collection sites is addressed. The primary degradation effects on stand-alone GPS positioning of Selective Availability (SA) are corrected using WADGPS, resulting in a significant improvement in position accuracy.

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Gou, Tsunekawa, Peng, Zhao, Li, and Lian. "Method for Classifying Behavior of Livestock on Fenced Temperate Rangeland in Northern China." Sensors 19, no. 23 (December 3, 2019): 5334. http://dx.doi.org/10.3390/s19235334.

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Different livestock behaviors have distinct effects on grassland degradation. However, because direct observation of livestock behavior is time- and labor-intensive, an automated methodology to classify livestock behavior according to animal position and posture is necessary. We applied the Random Forest algorithm to predict livestock behaviors in the Horqin Sand Land by using Global Positioning System (GPS) and tri-axis accelerometer data and then confirmed the results through field observations. The overall accuracy of GPS models was 85% to 90% when the time interval was greater than 300–800 s, which was approximated to the tri-axis model (96%) and GPS-tri models (96%). In the GPS model, the linear backward or forward distance were the most important determinants of behavior classification, and nongrazing was less than 30% when livestock travelled more than 30–50 m over a 5-min interval. For the tri-axis accelerometer model, the anteroposterior acceleration (–3 m/s2) of neck movement was the most accurate determinant of livestock behavior classification. Using instantaneous acceleration of livestock body movement more precisely classified livestock behaviors than did GPS location-based distance metrics. When a tri-axis model is unavailable, GPS models will yield sufficiently reliable classification accuracy when an appropriate time interval is defined.

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Huang, Xin, Yazhou Chen, and Yuming Wang. "Simulation of Interference Effects of UWB Pulse Signal to the GPS Receiver." Discrete Dynamics in Nature and Society 2021 (July 17, 2021): 1–8. http://dx.doi.org/10.1155/2021/9935543.

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Ultra-wideband (UWB) pulse signal has an extremely narrow pulse width and wide frequency bandwidth, which overlaps with the operating frequency band of Global Position System (GPS) receivers, posing a potential threat to their performance. In response to this problem, through mathematical analysis and software simulation, the effects of UWB pulse signal under time-hopping-pulse position modulation (TH-PPM) on the performance of GPS receivers were studied. First, the expression and waveform of the UWB pulse signal were analyzed in the time-frequency domain, and it is concluded that the pulse repetition frequency (PRF) mainly affects the discrete spectrum of the UWB signal and the TH code period mainly affects the continuous spectrum. On this basis, the simulation on the power spectral density (PSD) of GPS signal and UWB signal under different pulse parameters was represented, from which a conclusion can be drawn that the PRF is the main factor impacting the PSD of the GPS signal. Furthermore, this paper analyzed the degradation of GPS receiver equivalent carrier-to-noise ratio (C/N0) and C/A code demodulation bit error rate (BER) under UWB interference, which are the crucial evaluating indicators of GPS signal quality. Eventually, we theoretically calculated the minimum interference level of the UWB interference signal to the GPS receiver, providing a theoretical reference for reducing the interference effects of UWB pulse signal on the performance of GPS receivers.

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Jwo, Dah-Jing. "GPS Receiver Performance Enhancement via Inertial Velocity Aiding." Journal of Navigation 54, no. 1 (January 2001): 105–17. http://dx.doi.org/10.1017/s0373463300001260.

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An integrated GPS/INS navigation system can employ inertial velocity information to produce a more robust system. For a stand-alone GPS receiver, decreasing the receiver tracking loop bandwidth reduces the probability of losing lock in a jamming or interference environment if vehicle dynamics are low. However, reduced bandwidth increases tracking errors when dynamics are present. Beyond a certain limit, it causes a serious degradation in the dynamic tracking loop performance. Providing inertial velocity aiding to the receiver tracking loops is an effective and popular treatment to help resolve this problem. In this paper, performance of the GPS receiver tracking loops using inertial velocity aiding will be investigated. Different types of tracking loops, from 1st to 3rd order, are covered. Following the discussion of the system architecture and derivation of the related transfer functions for the tracking loops, both with and without aiding, the system performance, including transient response, steady-state error, and noise bandwidth is evaluated.

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Baselga, Sergio, Luis García-Asenjo, Pascual Garrigues, and José Luis Lerma. "Inertial Navigation System Data Filtering Prior to GPS/INS Integration." Journal of Navigation 62, no. 4 (October 2009): 711–20. http://dx.doi.org/10.1017/s0373463309990117.

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In the integration of Global Positioning System (GPS) and Inertial Navigation System (INS), the commonly used Kalman filter provides satisfactory results if both sources of information are continuously available. However, GPS outages provoke a fast degradation of precision, especially in low dynamic trajectories such as a mobile platform device held by a human operator. To deal with this problem we propose a data-filtering scheme to apply to INS raw data prior to the integration with GPS. The proposed technique proves to be very valuable for mitigating the high short-term instability of raw INS data during the walking movement and is also capable of eliminating the induced undesirable human operator vibrations. Final imposed corrections adapted to the particular dynamical response of the INS sensor provide comparably accurate results and often better than those achieved in similar works with the use of the Kalman filter.

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Jabbar, Mushtak T., Eric M. Baer, and Salah M.S. Al-Atab. "Risk Assessment of Drifting Sand in Agricultural Lands in Basrah Province with the aid of ‘3S’ Techniques." Basrah J. Agric. Sci. 33, no. 1 (June 20, 2020): 1–16. http://dx.doi.org/10.37077/25200860.2020.32.1.01.

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There is a growing need to systematically assessment of drifting sand risk using Geo-information and related technologies for speed and accuracy. The drifting sand map in the southern part of Iraq was established with objective of providing the risk areas of soil loss and the methodology for spatial modeling with Wind Erosion Equation (WEQ) and Geo-information techniques. This analysis was carried out using ‘3S’ technologies [Remote Sensing (RS), Geographic Information System (GIS) and Global Position System (GPS)], with the layers extracted and manipulated from available topographic, climatic and soil maps, as well as satellite image (Thematic Mapping (TM) in 2003 and Enhanced Thematic Mapping (ETM) in 2016) and field survey data analyses. Each of the WEQ factors was digitally encoded in a GIS database to establish each factor’s layers. Simultaneously, the overlay operation with the WEQ model on the factor’s layers was digitally performed to produce the sandy degradation class. The study indicated that the severe erosion class covering an area of about 61.9% of the total area is very high with the degraded vegetation and is located in the southwest part of Iraq. Iraq faces serious environmental degradation problems that must be addressed immediately; failure to do so will greatly compound the cost and complexity of later remedial efforts, with environmental degradation beginning even now to pose a major threat to human well-being, especially among the poor.

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Shu, Liu, Feng, Xu, Qian, and Yang. "Analysis of Factors Affecting Asynchronous RTK Positioning with GNSS Signals." Remote Sensing 11, no. 10 (May 27, 2019): 1256. http://dx.doi.org/10.3390/rs11101256.

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For short baseline real-time kinematic (RTK) positioning, the atmosphere and broadcast ephemeris errors can be usually eliminated in double-differenced (DD) processing for synchronous observations. However, in the case of possible communication latency time, these errors may not be eliminated in DD treatments due to their variations during latency time. In addition, the time variation of these errors may present different characteristics among GPS, GLONASS, BDS, and GALILEO due to different satellite orbit and clock types. In this contribution, the formulas for studying the broadcast orbit and clock offset errors and atmosphere error in asynchronous RTK (ARTK) model is proposed, and comprehensive experimental analysis is performed to numerically show time variations of these errors and their impacts on RTK results from short-baselines among four systems. Compared with synchronous RTK, the degradation of position precision for ARTK can reach a few centimeters, but the accuracy degradation to a different degree by different systems. BDS and Galileo usually outperform GPS and GLONASS in ARTK due to the smaller variation of broadcast ephemeris error. The variation of broadcast orbit error is generally negligible compared with the variation of broadcast clock offset error for GPS, BDS, and Galileo. Specifically, for a month of data, the root mean square (RMS) values for the variation of broadcast ephemeris error over 15 seconds are 11.2, 16.9, 7.3, and 3.0 mm for GPS, GLONASS, BDS, and Galileo, respectively. The variation of ionosphere error for some satellites over 15 seconds can reach a few centimeters during active sessions under a normal ionosphere day. In addition, compared with other systems, BDS ARTK shows an advantage under high ionosphere activity, and such advantage may be attributed to five GEO satellites in the BDS constellation.

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Filjar, Renato, Tomislav Kos, and Serdjo Kos. "Klobuchar-Like Local Model of Quiet Space Weather GPS Ionospheric Delay for Northern Adriatic." Journal of Navigation 62, no. 3 (June 15, 2009): 543–54. http://dx.doi.org/10.1017/s0373463309005281.

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Ionospheric delay is the major source of satellite positioning system performance degradation. Designers of satellite positioning systems attempt to mitigate the impact of the ionospheric delay by deployment of correction models. For instance, the American GPS utilises a global standard (Klobuchar) model, based on the assumption that the daily distribution of GPS ionospheric delay values follows a biased cosine curve during day-time, while during the night-time the GPS ionospheric delay remains constant. Providing a compromise between computational complexity and accuracy, the Klobuchar model is capable of correcting up to 70% of actual ionospheric delay, mainly during quiet space weather conditions. Unfortunately, it provides a very poor performance during severe space weather, geomagnetic and ionospheric disturbances. In addition, a global approach in Klobuchar model development did not take into account particularities of the local ionospheric conditions that can significantly contribute to the general GPS ionospheric delay. Current research activities worldwide are concentrating on a better understanding of the observed GPS ionospheric delay dynamics and the relation to local ionosphere conditions.Here we present the results of a study addressing daily GPS ionospheric delay dynamics observed at a Croatian coastal area of the northern Adriatic (position ϕ=45°N, λ=15°E) in the periods of quiet space weather in 2007. Daily sets of actual GPS ionospheric delay values were assumed to be the time series of composite signals, consisting of DC, cosine and residual components, respectively. Separate models have been developed that describe components of actual GPS ionospheric delay in the northern Adriatic for summer and winter, respectively. A special emphasis was given to the statistical description of the residual component of the daily distribution of GPS ionospheric delay, obtained by removing DC (bias) and cosine components from the composite GPS ionospheric delay.Future work will be focused on further evaluation and validation of a quiet space weather GPS ionospheric delay model for the northern Adriatic, transition to a non-Klobuchar model, and on research in local GPS ionospheric delay dynamics during disturbed and severe space weather conditions.

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Yu, Li. "Research on GPS RAIM Algorithm Based on SIR Particle Filtering State Estimation and Smoothed Residual." Applied Mechanics and Materials 422 (September 2013): 196–203. http://dx.doi.org/10.4028/www.scientific.net/amm.422.196.

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The investigation presents a new approach based on SIR particle filtering state estimation and smoothed residual for GPS receiver autonomous integrity monitoring (RAIM), which adopted the difference value between the ideal observation values acquired by state estimation and the actual state observation values, and the log likelihood ratio (LLR) test based on probability density function of state-measurement was set up. Experimental results based on real GNSS data demonstrate that the algorithm can estimate the state precisely under non-Gaussian measurement noise, detect and isolate GPS satellite failures successfully and solve the performance degradation problem of RAIM algorithm based on Kalman filter. Therefore, experimental results validate the validity of SIR particle filtering state estimation and smoothed residual for RAIM.

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Falconì, Guillermo P., Jorg Angelov, and Florian Holzapfel. "Adaptive Fault–Tolerant Position Control of a Hexacopter Subject to an Unknown Motor Failure." International Journal of Applied Mathematics and Computer Science 28, no. 2 (June 1, 2018): 309–21. http://dx.doi.org/10.2478/amcs-2018-0022.

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Abstract This paper presents a fault tolerant position tracking controller for a hexarotor system. The proposed controller has a cascaded structure composed of a position and an attitude control loop. The nominal controller is augmented by an adaptive control allocation which compensates for faults and failures within the propulsion system without reconfiguration of the controller. Simultaneously, it is able to implement a degraded control strategy which prioritizes specific control directions in the case of extreme degradation. The main contribution is a controller that is a step closer to application scenarios by including outdoor GPS-based flight tests, onboard computation and the handling of unknown degradation and failure of any rotor.

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& Hussien, Khalaf. "ENVIRONMENT SENSITIVITY MAPS OF LAND DEGRADATION AND DESRTIFICATION USING MEDULAS MODEL AND REMOTE SENSING IN SHIRQAT CITY/IRAQ." IRAQI JOURNAL OF AGRICULTURAL SCIENCES 52, no. 3 (June 22, 2021): 697–711. http://dx.doi.org/10.36103/ijas.v52i3.1361.

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This research of aims to study environment sensitivity of desertification and land degradation using MEDULAS project and remote sensing in AL-Shirqat City/Salahadin/Iraq. A 10 soil pedons were chosen from study area depending on difference in soil preperties, landuse and causes of desertification and degradation as (Salinity, Erosion, Gypsum and vegetation cover). Soil profile description, soil samples and GPS were conducted. The physical (texture) and chemical (CaCO3, CaSO4.2H2O, O.M, EC and pH) properties were determined. The Soil were classified as Torrifluvents in the (P1, P2, P3), Torripsamments in the (P5 and P7), Calcigypsids in the (P6, P8 and P10) and Calcids in the P4. The landsat 8 image at 20sep. 2019 and 19 sep. 2013 were aquired in the spectral indices calculate and spatial maps by using ERDAS 15 and GIS 10.2. The result show contrast in soil propreties as sand, clay, soil gypsum, CaCO3, OM and EC that reflect on Soil Quality Index (SQI) which were (60)% poor quality and (40)% moderate quality degradation. While (19.10) % that moderate quality and 80.90% that poor quality for Vegetation Quality Index. The results show that 0.1% of the study area is classiﬁed as C1; 25.35% as C2; 74.55% of the areas as C3. The spectral indices as LAI, SI5, OSAVI were approporiate for monitor of desertification and degradation in study area. Add, spatial change in the spectral indices as NDVI and LAI. The results shown that MEDALUS model is a important model in the areas disposed to desertification and degradation.

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Jwo, Dah Jing, and Zi Ming Wen. "Neural Network Assisted Vector Tracking Loop for Bridging GPS Signal Outages." Applied Mechanics and Materials 764-765 (May 2015): 560–64. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.560.

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Signal blockage and reflections from buildings and other large, solid objects can lead to accuracy degradation. One of the merits of the Global Positioning System (GPS) vector tracking loop (VTL) architectures is that the tracking loop can be assisted in such degraded signal environments. This paper proposes the incorporation of the neural network (NN) into the VTL for improving the positioning quality. The NN is used to bridge the GPS signal and prevent the error growth due to signal outage from spreading into the entire tracking loop. The NNs are employed for predicting adequate numerical control oscillator (NCO) inputs, i.e., providing better prediction of residuals for the Doppler frequency and code phase in order to maintain regular operation of the navigation system. The NN-assisted VTL demonstrates the capability to ensure proper functioning of navigation system. Results show that the NN-assisted VTL can effectively provide improved performance during degraded signal environments such as GPS outages.

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Journal articles on the topic 'GPS degradation'

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