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- 摘要
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- 实验方案
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Which active optical sensor vegetation index is best for nitrogen assessment in irrigated cotton?
摘要： Use of active optical sensors (AOS) in nitrogen (N) management of row crops continues to grow. Since the first studies in the mid-1990s, several commercial AOS are now available. Typically, canopy reflectance in red and near infrared (NIR) bands are used to calculate the normalized difference vegetation index (NDVI). More recently, commercially available AOS include a third, red-edge band that allows the calculation of additional vegetation indices (VIs). We present two studies of five site-years of N management studies in Maricopa, AZ on a Casa Grande sandy loam with cotton (Gossypium hirsutum L.). The 2014-2015 study was conducted under an overhead sprinkler irrigation system (OSI), and the 2016-2018 study was in subsurface drip irrigation (SDI). The study objective was to compare the ability of 12 different VIs to detect N deficiency among N treatments from shortly after emergence to mid-bloom. In the OSI study, which showed delayed, small N treatment effects, NDRE and the chlorophyll index using amber (CIRE) detected N deficiency in zero-N and in reduced N-reflectance-based plots 7-23 days before other VIs did. With SDI, the choice of VI was less critical as several VIs could distinguish N deficiency in zero-N and in reflectance plots. The commonly used NDVI red (NDVIR) only detected N deficiency in reflectance plots in one of five site-years. In conclusion, we recommend the use of AOS with NIR and red-edge bands and the calculation of NDRE or CIRE to guide AOS-based in-season N management of irrigated cotton.
关键词： N fertilizer management,proximal sensing,lint yields,plant biomass,plant N
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE Transportation Electrification Conference and Expo, Asia-Pacific (ITEC Asia-Pacific) - Seogwipo-si, Korea (South) (2019.5.8-2019.5.10)] 2019 IEEE Transportation Electrification Conference and Expo, Asia-Pacific (ITEC Asia-Pacific) - Optimal scheduling of critical peak pricing considering photovoltaic generation and electric vehicle load
摘要： For long-wavelength space-based radars, such as the P-band radar on the recently selected European Space Agency BIOMASS mission, system distortions (crosstalk and channel imbalance), Faraday rotation, and system noise all combine to degrade the measurements. A first-order analysis of these effects on the measurements of the polarimetric scattering matrix is used to derive differentiable expressions for the errors in the polarimetric backscattering coefficients in the presence of Faraday rotation. Both the amplitudes and phases of the distortion terms are shown to be important in determining the errors and their maximum values. Exact simulations confirm the accuracy and predictions of the first-order analysis. Under an assumed power-law relation between σhv and the biomass, the system distortions and noise are converted into biomass estimation errors, and it is shown that the magnitude of the deviation of the channel imbalance from unity must be 4–5 dB less than the crosstalk, or it will dominate the error in the biomass. For uncalibrated data and midrange values of biomass, the crosstalk must be less than ?24 dB if the maximum possible error in the biomass is to be within 20% of its true value. A less stringent condition applies if the amplitudes and phases of the distortion terms are considered random since errors near the maximum possible are very unlikely. For lower values of the biomass, the noise becomes increasingly important because the σhv signal-to-noise ratio is smaller.
关键词： Biomass,Faraday rotation,polarimetric measurements,system distortion,calibration,long-wavelength radar
更新于2025-09-23 15:19:57
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Modal Analysis of 2-D Material-based Plasmonic Waveguides by Mixed Spectral Element Method with Equivalent Boundary Condition
摘要： For long-wavelength space-based radars, such as the P-band radar on the recently selected European Space Agency BIOMASS mission, system distortions (crosstalk and channel imbalance), Faraday rotation, and system noise all combine to degrade the measurements. A first-order analysis of these effects on the measurements of the polarimetric scattering matrix is used to derive differentiable expressions for the errors in the polarimetric backscattering coefficients in the presence of Faraday rotation. Both the amplitudes and phases of the distortion terms are shown to be important in determining the errors and their maximum values. Exact simulations confirm the accuracy and predictions of the first-order analysis. Under an assumed power-law relation between σhv and the biomass, the system distortions and noise are converted into biomass estimation errors, and it is shown that the magnitude of the deviation of the channel imbalance from unity must be 4–5 dB less than the crosstalk, or it will dominate the error in the biomass. For uncalibrated data and midrange values of biomass, the crosstalk must be less than ?24 dB if the maximum possible error in the biomass is to be within 20% of its true value. A less stringent condition applies if the amplitudes and phases of the distortion terms are considered random since errors near the maximum possible are very unlikely. For lower values of the biomass, the noise becomes increasingly important because the σhv signal-to-noise ratio is smaller.
关键词： Biomass,Faraday rotation,polarimetric measurements,system distortion,calibration,long-wavelength radar
更新于2025-09-23 15:19:57
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In-situ measurement of potassium release during biomass combustion using laser-induced breakdown spectroscopy: effect of silicate on potassium release
摘要： In this study, an improved calibration method for the in-situ measurement of potassium (K), concentration in the flame field was developed using laser induced breakdown spectroscopy (LIBS). The temporal behaviors of K release and particle temperature were recorded simultaneously during biomass combustion. During combustion of raw willow wood, the majority of K was released during ash-cooking stage, followed by char combustion stage, only a small amount of K was released during the initial devolatilization stage. The results indicated during devolatilization stage K was released due to the decomposition of organic K. Char- K was subsequently converted to K2CO3 and most K2CO3 was subsequently released during final ash-cooking stage. In the case of rice straw combustion, K was mainly released during the initial devolatilization stage, most likely as KCl. The transformation of char-K and the K-Si reaction forming K-silicates mainly occurred during char combustion stage, K was found to be released slowly from K-silciates during ash-cooking stage. The combustion of willow wood with different Si contents demonstrated that Si significantly inhibited the K release during both char combustion and ash-cooking stage.
关键词： release,LIBS,biomass,combustion,Potassium,silicate
更新于2025-09-23 15:19:57
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Blue luminescence carbon quantum dots derived from oil palm empty fruit bunch biomass
摘要： Carbon quantum dots (CQDs) have attracted tremendous attention for their interesting properties such as excellent chemical and photo stability, good water dispersibility, biocompatibility and possessing outstanding photoluminescence (PL) properties. In this study, oil palm biomass is used as the carbon precursor to produce CQDs and exhibit high luminescent properties. However, a large amount of biomass produces by the oil palm industry is either burnt in the open air or disposed in waste ponds and contributes to global climate change via emissions of carbon dioxide and methane. Hence, synthesis the CQDs from oil palm biomass by hydrothermal treatment method has formed excellent properties in optical properties that could be comparable to semiconductor quantum dots. The results have shown the diameter size of CQDs in the range of 2-5 nm. While, the optical properties, UV-vis spectrum of CQDs have given a strong absorption at 282 nm and obtains in brown color under visible light and emitting blue luminescence under 365 nm of UV lamp. Furthermore, PL spectra of CQDs have shown excitation and emission wavelength at 360 nm and 450 nm, respectively. This is attribute to the excitation-wavelength dependent of PL properties. Hence, the spectra from FTIR showed the existence of hydroxyl and carboxyl groups on the CQDs would have originated from lignocellulosic materials, thus resulted in excellent water stability and solubility properties of CQDs. The presented study is the green approached reprocessed biomass from waste to materials with excellent optical properties that could utilize in various field of applications.
关键词： hydrothermal treatment,photoluminescence,optical properties,Carbon quantum dots,oil palm biomass
更新于2025-09-23 15:19:57
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Photocatalytic Hydrogen Generation Coupled to Pollutant Utilization Using Carbon Dots Produced from Biomass
摘要： Photocatalysis is deemed as an appealing strategy to exploit solar energy for simultaneous fuel production and pollutant utilisation. However, current photocatalytic systems rarely couple both processes and suffer from restricted scalability and sustainability as they use toxic and/or ultraviolet light harvesters, combined with noble-metal co-catalysts under corrosive conditions. Here, we show the synthesis of ultra-scalable and low-cost carbon nanodots from lignocellulosic waste, which when combined with a non-precious Ni-based co-catalyst, use visible light to drive H2 production in untreated river and sea water. Organic pollutants and chloride anions in these untreated media do not only allow unhindered photocatalytic activities, but also function as electron donors leading to economical pollutant utilisation. This system combines Earth’s most abundant resources (biomass, solar energy, untreated water), and functions at ambient temperature, pressure and physiological pH creating perspectives for simultaneous fuel synthesis and pollutant utilisation of sustainable and practical character.
关键词： Pollutant utilisation,Carbon dots,Photocatalysis,Biomass waste,Hydrogen production
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - High Performance Ultrafast Thulium-Doped Fiber Lasers
摘要： The temporal variations (diurnal and annual) in arboreal (εTree) and bare soil (εSoil) dielectric constants and their correlation with precipitation were examined for several trees in Japan. A significant (1 σ (standard deviation) and 2 σ) εTree increase is observed after rainfall at 89.8% and 90.5% probability. However, rainfall does not always induce significant εTree increases. Rainfall of more than 5 mm/day can induce 1 σ εTree increase at a 59.6% probability. In order to examine whether the increase in εTree affects the L-band σ0 variation in a forest, the four-year temporal variation of the L-band backscattering coefficient (σ0) was estimated from observations by the Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar. Observed maximum absolute deviations from the mean over the forest area were 1.0 and 1.2 dB for σ0 HV, respectively, and 4.0 and 3.0 dB over open land. σ0 and rainfall correlations show that εTree and σ0 Forest are proportional to precipitation integrated over seven or eight days; εSoil and σ0 Open land are proportional to precipitation integrated over three days. This finding indicates that εTree variations influence σ0 Forest areas. A stronger correlation between σ0 HV and precipitation is observed in several sites with low σ0 HV, where less biomass is expected, and several sites with high σ0 HV, where more biomass is expected. A weaker correlation between σ0 HV and precipitation is observed for several sites with high σ0 HV. These differences may be explained by the different contributions of double bounce scattering and potential transpiration, which is a measure of the ability of the atmosphere to remove water from the surface through the processes of transpiration. The two other results were as follows: 1) The functional relation between aboveground biomass and σ0 showed dependence on precipitation data, this being an effect connected with seasonal changes of the εTree. This experiment reinforces the fact that the dry season is preferable for retrieval of woody biomass from inversion of the functional dependence of SAR backscatter and for avoiding the influence of rainfall. 2) The complex dielectric constant for a tree trunk, which is measured between 0.2 and 6 GHz, indicates that free water is dominant in the measured tree.
关键词： Biomass,temporal variation,forest,dielectric constant,Phased Array type L-band Synthetic Aperture Radar (PALSAR)
更新于2025-09-23 15:19:57
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Image analysis procedure for the optical scanning of fine-root dynamics: errors depending on the observer and root-viewing window size
摘要： Clarifying the dynamics of ?ne roots is critical to understanding carbon and nutrient cycling in forest ecosystems. An optical scanner can potentially be used in studying ?ne-root dynamics in forest ecosystems. The present study examined image analysis procedures suitable for an optical scanner having a large (210 mm × 297 mm) root-viewing window. We proposed a protocol for analyzing whole soil images obtained by an optical scanner that cover depths of 0–210 mm. We tested our protocol using six observers with di?erent experience in studying roots. The observers obtained data from the manual digitization of sequential soil images recorded for a Bornean tropical forest according to the protocol. Additionally, the study examined the potential tradeo? between the soil image size and accuracy of estimates of ?ne-root dynamics in a simple exercise. The six observers learned the protocol and obtained similar temporal patterns of ?ne-root growth and biomass with error of 10–20% regardless of their experience. However, there were large errors in decomposition owing to the low visibility of decomposed ?ne roots. The simple exercise revealed that a smaller root-viewing window (smaller than 60% of the original window) produces patterns of ?ne-root dynamics that are di?erent from those for the original window size. The study showed the high applicability of our image analysis approach for whole soil images taken by optical scanners in estimating the ?ne-root dynamics of forest ecosystems.
关键词： minirhizotron,decomposition,error,root distribution,biomass production
更新于2025-09-23 15:19:57
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Forest Aboveground Biomass Estimation Using a Combination of Sentinel-1 and Sentinel-2 Data
摘要： Estimation of forest aboveground biomass is crucial for carbon accounting and forest management. In this paper we present the estimation of forest above ground biomass derived from a combination of Sentinel-1 and Sentinel-2 data using the Random Forest Regression approach. The research was conducted over a temperate forest in Poland, where the forest biomass is ranging from 1 to 300 t/ha. The results revealed a saturation effect around 200 t/ha. The biomass model tends to overestimate small values of aboveground biomass and underestimate larger values of biomass (greater than 250 t/ha). The overall RMSE value is equal to 60 t/ha, however it varies for biomass ranges. The independent validation performed at the forest stand level showed the best agreement for biomass ranging for 100-200 t/ha. This research was conducted as part of the ESA funded DUE GlobBiomass project.
关键词： temperate forest,GlobBiomass,Sentinel,SAR,biomass
更新于2025-09-19 17:15:36
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Carbonaceous Biomass-Titania composites with Ti–O–C Bonding Bridge for Efficient Photocatalytic Reduction of Cr(VI) Under Narrow Visible Light
摘要： The aim of this study was to develop carbonaceous materials hybridized with anatase TiO2 composed of Activated Carbon-TiO2 (AC-TiO2), Olive Pits-TiO2 (OP-TiO2) and Wood Shaving-TiO2 (WS-TiO2) by ultrasonic-assisted sol-gel process for the photocatalytic Cr(VI) reduction under UV and narrow visible light. The morphology, crystal structure, surface chemistry and optical properties of the as-prepared and bare-TiO2 were investigated by SEM-EDS, XRD, FTIR, BET, UV-DRS, XPS and photo-current measurements. Unlike bare-TiO2, these composite photocatalysts exhibited an enhanced absorption in visible-light. The band gap energies were found to be 3.20 eV, 2.89 eV, 2.81 eV and 2.95 eV for bare-TiO2, AC-TiO2, OP-TiO2 and WS-TiO2, respectively. On the other hand, as-prepared photocatalysts showed significantly improved photocatalytic Cr(VI) reduction performances under UV and visible light illumination compared to bare-TiO2. A total reduction of 10 ppm of Cr(VI) was obtained after 30 min, 50 min and 130 min under visible light (>420) for AC-TiO2, OP-TiO2 and WS-TiO2, respectively at pH: 3 and in the presence of 10 ppm tartaric acid as hole scavenger, while no reduction was detected for bare-TiO2 under visible light (>420). The efficient photocatalytic reduction of Cr(VI) under visible light by AC-TiO2, OP-TiO2 and WS-TiO2 was mainly due to (i): the narrow band gap of TiO2 nanoparticle deposited in carbonaceous materials, (ii): self-photo-sensitizer role of carbonaceous materials via Ti–O–C bonds and (iii): the electron transfer from TiO2 to carbonaceous materials.
关键词： Cr(VI) Reduction,Environmental remediation.,Visible Light,Photocatalysis,Carbonaceous Biomass-TiO2,Band-gap Narrowing
更新于2025-09-19 17:15:36