Reflectance Ratio Research Articles

Mapping Underwater Bathymetry of a Shallow River from Satellite Multispectral Imagery

Rivers play an important role in water supply, waterway transport, and riverine species habitations. The underwater depth of a river channel is a fundamental geometric element and a key input to studies for the aforementioned and other applications. Traditional in-situ field surveys for flow depth measurements would incur high costs and encounter technical and/or logistical difficulties, particularly for river channels of large extents, very shallow channels, and remote, inaccessible channels. Recent advances in satellite remote sensing of inland water bodies like rivers, streams, and creeks have allowed mapping flow depth in an inexpensive, convenient, and efficient manner. The purpose of this paper is to demonstrate the retrieval of river flow depth from high-resolution (1.2 m) WorldView-3 satellite imagery. The depth retrieval methods are based on the ratio of top-of-atmosphere reflectance between two pairing wavelength bands of multispectral imagery. The originality of the methods lies in using analytical relationships without resorting to ground data of river flow depth for calibration, which improves from previous studies of remote sensing of river flow depth. The methods are successfully applied to mapping the underwater bathymetry of a 26 km reach of the Nicolet River in Quebec, Canada. This study shows the importance of geometric and radiometric corrections to the satellite images. The obtained flow depths using the ratio of reflectance of the red band (630–690 nm) to that of the green band (510–580 nm), among the eight bands in the visible spectrum, agree best with in-situ measurements. This study is perhaps the first use of the analytical approach for mapping river bathymetry. It is feasible to implement the approach to other river channels, with a good potential to reduce the costs and increase the efficiency of mapping river bathymetries.

Biomarkers to Predict the Success of Treatment with the Intravitreal 0.19 mg Fluocinolone Acetonide Implant in Uveitic Macular Edema.

To predict the need for additional local corticosteroids after receiving the 0.19 mg fluocinolone acetonide (FAc) implant in patients with macular edema secondary to non-infectious uveitis previously treated with local peribulbar corticosteroids. The number of corticosteroids required prior FAc, visual acuity, central retinal thickness, ellipsoid zone reflectivity ratio (EZR), and choroidal vascularity index (CVI) were compared between patients who did and did not require additional corticosteroids after FAc implantation. Pearson’s correlation coefficient (R) between putative predictors and the number of adjunctive corticosteroids after FAc implantation were measured; significant candidates were included in a generalized regression model. Patients who required additional corticosteroids after FAc had higher CVI and central retinal thickness as well as worse EZR at subsequent visits (p < 0.05). The number of corticosteroids required prior to FAc implantation (R: 0.49), CVI change from baseline to 6 months (R: −0.41), and central retinal thickness at baseline (R: −0.36) correlated to the number of additional corticosteroids (all p < 0.05). A higher number of corticosteroids per year before FAc implantation was predictive for an increase in corticosteroids required after FAc (odds ratio = 2.65), while a decrease in CVI from baseline to 6 months was inversely correlated (odds ratio = 0.82). Our results suggest that the more corticosteroids prior to FAc and the greater the short-term CVI reducing effect, the less is the chance to get additional corticosteroids after FAc.

Research on a Partial Aperture Factor Measurement Method for the AGRI Onboard Calibration Assembly.

A partial aperture onboard calibration method can solve the onboard calibration problems of some large aperture remote sensors, which is of great significance for the development trend of increasingly large apertures in optical remote sensors. In this paper, the solar diffuser reflectance degradation monitor (SDRDM) in the onboard calibration assembly (CA) of the FengYun-4 (FY-4) advanced geostationary radiance imager (AGRI) was used as the reference radiometer. It was designed for measuring the partial aperture factor (PAF) for the AGRI onboard calibration. First, the linear response count variation relationship between the two was established under the same radiance source input. Then, according to the known bidirectional reflection distribution function (BRDF) of the solar diffuser (SD) in the CA, the relative reflectance ratio coefficient between the AGRI observation direction and the SDRDM observation direction was calculated. On this basis, the response count value of the AGRI and the SDRDM was used to realize the high-precision measurement of the PAF of the AGRI B1~B3 bands by simulating the AGRI onboard calibration measurement under the illumination of a solar simulator in the laboratory. According to the determination process of the relevant parameters of the PAF, the measurement uncertainty of the PAF was analyzed; this uncertainty was greater than 2.04% and provided an important reference for the evaluation of the onboard absolute radiometric calibration uncertainty after launch.

Whole-Plant Tissue Nitrogen Content Measurement Using Image Analyses in Floriculture Crops

AbstractResearch on image analysis techniques for estimating plant N status in floriculture is limited. We subjected poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cultivars to five nitrogen concentration treatments for 45 days and captured grayscale images of plants briefly exposed to 450, 625, 660, and 870 nm of light using a multispectral image station. Images were processed to calculate normalized reflectance ratios, including R870/450, R870/625, and R870/660. Dried shoots were analyzed in a laboratory for whole-plant tissue N content (mg·g−1). Results indicated that whole-plant N content ranged from 21 to 44 mg·g−1 in different N treatments. Among the reflectance ratios, R870/625 showed higher correlation with whole-plant N content in different cultivars of poinsettia (0.72&amp;lt; r2 &amp;lt;0.78) compared to R870/450 and R870/660. Based on these results, we custom-built a low-cost image sensor that can be remotely controlled to capture red (625 nm) and near infrared (870 nm) images of plants and transfer images to a cloud storage for processing. The normalized reflectance ratio measured by the image sensor was linearly related to the whole-plant N content (r2=0.84) and more accurate than soil plant analysis development (SPAD) measurements at predicting plant N status. These results indicate that image analysis in general and images captured by low-cost image sensors can be used for estimation of plant N status in floriculture.Index words: Chlorophyll, poinsettia, red light reflectance, plant segmentation.Chemicals used in this study: Water soluble 15-5-15 Cal Mg.Species used in this study: Poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch, cultivars ‘Christmas Beauty Marble', ‘Christmas Tradition', ‘Christmas Glory White', and ‘Wintersun White').

Study on Energy Dissipation Characteristics and Damage Law of Backfill under Cyclic Impact

This research aims to study the damaging effect of underground blasting mining pillars on adjacent cemented filling bodies. The filling bodies were made by mixing ore rock with ash sand by the ratio of 1 : 4 and 1 : 6, respectively, which were subjected to cyclic impact tests with the split-Hopkinson pressure bar under the pressure of 0.2 MPa and 0.24 MPa to analyze the energy dissipation characteristics and damage law. The results showed that as the stress wave induced by the cyclic impact was transmitted to the composite specimen, the energy was absorbed for crack growth and development. Then, the energy reflection ratio increased while the energy dissipation ratio and transmission ratio decreased. For the combined specimen with the cement-sand ratio of 1 : 4, after five cycles of impact under the condition of Ip = 0.2 MPa, the damage variables were 0.07, 0.11, 0.51, and 0.56, respectively, since the second time; under the condition of Ip = 0.24 MPa, the damage variables were 0.17, 0.29, 0.55, and 0.66, respectively. After reaching the damage threshold of 0.63, the damage variable showed nonlinearity. Moreover, it was found that the mechanical properties of the filling body affect the whole combined specimen, and the dynamic strength of the combined specimen with the cement-sand ratio of 1 : 4 was higher than that of the cement-sand ratio of 1 : 6. Therefore, it can be concluded that during the two-step pillar recovery, the amount of blasting explosive can be appropriately reduced, and the number of blasting can be increased to reduce the damaging effect of blasting impact on the cemented pillar and reserved pillar to maintain stability.

The Role of Specular Reflections and Illumination in the Perception of Thickness in Solid Transparent Objects.

Specular reflections and refractive distortions are complex image properties of solid transparent objects, but despite this complexity, we readily perceive the 3D shapes of these objects (e.g., glass and clear plastic). We have found in past work that relevant sources of scene complexity have differential effects on 3D shape perception, with specular reflections increasing perceived thickness, and refractive distortions decreasing perceived thickness. In an object with both elements, such as glass, the two optical properties may complement each other to support reliable perception of 3D shape. We investigated the relative dominance of specular reflection and refractive distortions in the perception of shape. Surprisingly, the ratio of specular reflection to refractive component was almost equal to that of ordinary glass and ice, which promote correct percepts of 3D shape. The results were also explained by the variance in local RMS contrast in stimulus images but may depend on overall luminance and contrast of the surrounding light field.

Texturing of polydimethylsiloxane surface for anti-reflective films with super-hydrophobicity in solar cell application

This study utilized a Cu metal assisted chemical etching (MACE) method to produce an anti-reflection texture on poly dimethyl siloxane (PDMS). We measured the diffuse and total transmittance, total reflectance, and haze ratio to analyze the optical properties of the textured PDMS films, which were confirmed using finite-difference time-domain (FDTD) calculations. The anti-reflection textured PDMS films exhibited improved optical performance in the visible light region, owing to the light scattering and trapping effect, by improving the lateral surface area and aspect ratio of the micro/nanostructures. The average reflectance was 2.86% under optimal conditions. The optimized structures of the films also showed super-hydrophobicity (θCA≈155.2°). We applied the optimized film to perovskite photovoltaic solar cell devices and observed an enhanced short-circuit current density (Jsc) from approximately 21.95 to 24.06 mA/cm2 (∼9% increase). The improved Jsc increased the PCE to 17.11% (∼11% increase) in the MAPbI3 p-i-n structured devices. Based on the results, we confirmed that the superhydrophobic anti-reflection PDMS film can be used to overcome the limitation of light absorption in solar cell applications.

Semi-Automated Quantification of Retinal and Choroidal Biomarkers in Retinal Vascular Diseases: Agreement of Spectral-Domain Optical Coherence Tomography with and without Enhanced Depth Imaging Mode.

Background: We compared with and without enhanced depth imaging mode (EDI) in semi-automated quantification of retinal and choroidal biomarkers in optical coherence tomography (OCT) in patients with diabetic retinopathy (DR) or retinal vein occlusion (RVO) complicated by macular edema. We chose to study three OCT biomarkers: the numbers of hyperreflective foci (HF), the ellipsoid zone reflectivity ratio (EZR) and the choroidal vascularity index (CVI), all known to be correlated with visual acuity changes or treatment outcomes. Methods: In a single examination, one eye of each patient (n = 60; diabetic retinopathy: n = 27, retinal vein occlusion: n = 33) underwent macular 870 nm spectral domain-OCT (SD-OCT) B-scans without and with EDI mode. Semi-automated quantification of HF, EZR and CVI was applied according to preexisting published protocols. Paired Student’s t-test or Wilcoxon rank-sum test was used to test for differences in subgroups. Intraclass correlation coefficient (ICC) and Bland–Altman plots were applied to describe the agreement between quantification in EDI and conventional OCT mode. The effect of macular edema on semi-automated quantification was evaluated. Results: For the entire cohort, quantification of all three biomarkers was not significantly different in SD-OCT scans with and without EDI mode (p > 0.05). ICC was 0.78, 0.90 and 0.80 for HF, EZR and CVI. The presence of macular edema led to significant differences in the quantification of hyperreflective foci (without EDI: 80.00 ± 33.70, with EDI: 92.08 ± 38.11; mean difference: 12.09, p = 0.03), but not in the quantification of EZR and CVI (p > 0.05). Conclusion: Quantification of EZR and CVI was comparable whether or not EDI mode was used. In conclusion, both retinal and choroidal biomarkers can be quantified from one single 870 nm SD-OCT EDI image.

Internal damages detection for structural timber members using low-frequency anti-symmetric guided wave

Structural timber is one of the commonly used construction materials. Timber can contain natural internal defect such as knot or natural decay due to its anatomical complexity. Moreover, internal damages or stiffness reductions can also be induced by environmental and biological factors such as weathering and termite attacks. This hidden internal damage increases the difficulty of damage detection using conventional non-destructive testing (NDT) methods. Ultrasonic guided wave (GW) damage detection technique is one of the promising damage detection techniques, which can be employed to achieve an effective and robust damage inspection in timber. However, limited attention has been paid to the use of GW for damage detection in timber, due to the material anisotropy and inhomogeneity. This paper assesses the capability of GW in detecting different sizes of the internal damages in a structural red oak timber using the fundamental anti-symmetric mode (A0) of GW. Measured GW signals in forward and backward scattering directions are used to calculate the reflection and transmission ratios for different sizes of internal damages. A series of comprehensive experimental and numerical parametric studies are carried out using three-dimensional (3D) finite element (FE) simulations. Good agreement is obtained between numerical and experimental results. The experimentally verified FE model is utilized to further investigate the wave reflection and transmission phenomena from different characteristics of internal damages, such as different lengths, widths, thicknesses, and through thickness locations. The outcomes of this study demonstrate the robustness of GW technique in detecting conspicuous internal damages in structural timber. It demonstrates the feasibility of quantitative assessments of internal damages in timber using A0 GW.

Characterisation of progression of macular oedema in the initial stages of diabetic retinopathy: a 3-year longitudinal study

Background/objectivesTo characterise the prevalence and three-year progression of centre-involving diabetic macular oedema (CI-DMO) in minimal to moderate non-proliferative diabetic retinopathy, using optical coherence tomography (OCT) and measurements of retinal fluid using tissue optical reflectivity ratios (OCT-Leakage).Methods/methodsSeventy-four eyes from 74 patients were followed in a 3-year prospective longitudinal observational cohort of type 2 diabetes (T2D) patients using spectral-domain optical coherence tomography (SD-OCT), OCT-Angiography (OCT-A) and OCT-Leakage (OCT-L). Eyes were examined four times with 1-year intervals. Sixteen eyes (17.8%) were excluded from the analysis due to quality control standards. Retinal oedema was measured by central retinal thickness and retinal fluid by using optical reflectivity ratios obtained with the OCT-L algorithm. Vessel density was measured by OCT-A. Thinning of the ganglion cell and inner plexiform layers (GCL + IPL) was examined to identify retinal neurodegenerative changes. Diabetic retinopathy ETDRS classification was performed using the seven-field ETDRS protocol.ResultsCI-DMO was identified in the first visit in 9% of eyes in ETDRS groups 10–20, 10% of eyes in ETDRS group 35 and 15% of eyes in ETDRS groups 43–47. The eyes with CI-DMO and subclinical CI-DMO showed a progressive increase in retinal extracellular fluid during the 3-year period of follow-up. The eyes with CI-DMO and increased retinal extracellular fluid accumulation were associated with vision loss.ConclusionsThe prevalence of subclinical CI-DMO and CI-DMO in the initial stages of NPDR occurs independently of severity grading of the retinopathy, showing progressive increase in retinal extracellular fluid and this increase is associated with vision loss (82% 9 out of 11 cases).

Pulmonary arterial pressure in fattened Angus steers at moderate altitude influences early postmortem mitochondria functionality and meat color during retail display.

Pulmonary hypertension is a noninfectious disease of cattle at altitudes > 1524 m (5,000 ft). Mean pulmonary arterial pressures (PAP) are used as an indicator for pulmonary hypertension in cattle. High PAP cattle (≥50 mmHg) entering the feedlot at moderate elevations have lower feed efficiency as compared to low PAP cattle (< 50 mmHg). The impact of pulmonary arterial pressure on mitochondrial function, oxidative phosphorylation (OXPHOS) protein abundance, and meat color was examined using longissimus lumborum (LL) from high (98±13 mmHg; n = 5) and low (41±3 mmHg; n = 6) PAP fattened Angus steers (live weight of 588±38kg) during early postmortem period (2 and 48h) and retail display (days 1 to 9), respectively. High PAP muscle had greater (P = 0.013) OXPHOS-linked respiration and proton leak-associated respiration than low PAP muscles at 2h postmortem but rapidly declined to be similar (P = 0.145) to low PAP muscle by 48h postmortem. OXPHOS protein expression was higher (P = 0.045) in low PAP than high PAP muscle. During retail display, redness, chroma, hue, ratio of reflectance at 630 and 580nm, and metmyoglobin reducing activity decreased faster (P < 0.05) in high PAP steaks than low PAP. Lipid oxidation significantly increased (P < 0.05) in high PAP steaks but not (P > 0.05) in low PAP. The results indicated that high PAP caused a lower OXPHOS efficiency and greater fuel oxidation rates under conditions of low ATP demand in premortem beef LL muscle; this could explain the lower feed efficiency in high PAP feedlot cattle compared to low PAP counterparts. Mitochondrial integral function (membrane integrity or/and protein function) declined faster in high PAP than low PAP muscle at early postmortem. LL steaks from high PAP animals had lower color stability than those from the low PAP animals during simulated retail display, which could be partially attributed to the loss of muscle mitochondrial function at early postmortem by ROS damage in high PAP muscle.

Radiometric Calibration Scheme for COCTS/HY-1C Based on Image Simulation From the Standard Remote-Sensing Reflectance

The data quality of the satellite-retrieved water-leaving reflectance (Rrs) depends on the accuracy of radiometric calibration and the performance of atmospheric correction. A radiometric calibration scheme (RCS) has been developed to ensure the accuracy of Rrs through the gain adjustment factors (GAFs) to adjust the satellite calibrated data. The GAF is obtained from the ratio of the simulated reflectance at the top of atmosphere to the calibrated values. The simulated reflectance is computed by a satellite image simulation model (SISM) based on a dataset of climatological global Rrs images according to the same geometric angles of the image pixels. The dataset, taken as a kind of the pseudo-invariant calibration sites for in situ measurements, is generated from the average of standard satellite-retrieved Rrs during more than two decades (1997-2019). The SISM inputs the aerosol properties retrieved from the satellite level 1B data (L1B) and uses the same algorithms of the data-processing system. The results show that the accuracy of the calibration of the website downloaded Chinese Ocean Color and Temperature Scanner on the Haiyang-1C satellite (COCTS/HY-1C) is beyond the requirement of the operational data-processing system (higher than 10%). The daily GAFs can be used to recalibrate the L1B data and monitor the daily sensor degradations. The influences of GAFs are assessed on different meteorological conditions, indicating that the values decrease with the increase of the aerosol optical depths (AODs) but the average of the GAF image is little affected by the meteorological conditions. The uncertainty of GAFs was tested by the different inputs of Rrs values and the results show that they are actually little affected by errors of the Rrs inputs. Therefore, the RCS, taking the advantage of vicarious calibration, offers a tool to recalibrate the COCTS/HY-1C L1B data for the data reprocessing system.

INTENSITY CONTROLLED, NONSPECULAR RESONANT BACK REFLECTION OF LIGHT

Subject and Purpose. Theoretical demonstration of controllable features of a non-conventional resonant back reflection of light, realizable with the aid of a structured silicon-on-metal covering. Methods and Methodology. The investigation has been performed through a full-wave numerical simulation in a finite-element technique. Results. The nonlinear optical properties of a planar structure, involving a set of silicon disks disposed periodically on a silver substrate, have been studied in the Littrow scenario of wave reflection. The structure manifests a bistable resonant reflectivity property. The magnitudes of both specular and back reflection ratios can be controlled by means of varying the incident light intensity. Conclusions. An array of identical silicon disks, placed in a periodic order on a silver substrate, can be employed as an efficiently excitable and tunable nonlinear resonant reflective structure implementing Littrow’s non-specular diffraction scenario. As has been found, the effect of nonlinear response from the silicon disks can be used for implementing a regimen of bistable back reflection, controllable by means of varying the incident wave’s intensity. The nonlinear tunability of the silicon-on-silver structure does promise extensions of the operation area of classical metamaterials of sub-wavelength scale sizes as it offers new

Aerosol Retrieval Algorithm for Sentinel-2 Images Over Complex Urban Areas

High-resolution aerosol retrieval is of great significance for understanding the impact of aerosols on air pollution and climate change. In this study, an algorithm for aerosol retrieval at a spatial resolution of 60 m over complex urban areas is developed using Sentinel-2 images. The proposed algorithm has two assumptions: 1) the blue&#x2013;red surface reflectance ratio does not change temporally in a single season and 2) surface reflectance over bright areas is invariant over three months. Then, the aerosol optical depth (AOD) is retrieved from the surface reflectance correlations with a combination of temporal signatures over the vegetated areas and bright areas. The aerosol robotic network (AERONET) measurements in Beijing and its surrounding from 2017 to 2019 are collected and used to validate the retrieved 60-m Sentinel-2 AODs; 77&#x0025; of the retrieved Sentinel-2 AODs fall within the expected error (EE), and the correlation coefficient is of 0.927. MODerate resolution Imaging Spectroradiometer (MODIS) AOD products at 1- and 10-km resolutions (MCD19A2 and MOD04&#x005F;L2, respectively) are acquired to compare with the retrieved Sentinel-2 AODs. Comparison results show that the retrieved Sentinel-2 AODs are superior to the MOD04&#x005F;L2 dark target (DT) and MCD19A2 AODs, and slightly better than the MOD04&#x005F;L2 deep blue (DB), and DT and DB combined (DTBC) AODs. The validation and comparison results indicate that the proposed algorithm is able to describe aerosol distributions at high resolution continuously. However, further work is needed to apply the proposed algorithm on a global scale.

Ultrasonic Imaging of Seismic Physical Models Using an Ultra-Thin Open-Cavity Microbubble Sensor

A sensitivity-improved fiber-optic ultrasonic sensor is proposed and employed for ultrasonic imaging of seismic physical models (SPMs). The sensor consists of a single mode fiber (SMF) embedded into the hollow-core-fiber (HCF) bubble. Using gas pressure assisted arc discharge, the diameter of the bubble can be larger than 430 um with a wall thickness of approximately 0.48 um. Besides, by using the coating technique, the optical reflectivity and extinction ratio of the ultra-thin bubble are further improved. Fiber tails of SMF and the HCF are partly bonded to form an open-cavity sensor. When applied with ultrasonic waves (UWs), the compact bubble can balance the difference of air pressure between inside and outside. Eventually, a side-band filter technique is used for UWs interrogation. Compared with enclosed uncoating fiber bubble, the sensor shows an enhanced response to pulsed ultrasound. The SPMs of rugged topography and reservoir type are both designed and the proposed sensor is used for ultrasonic imaging of the two specific models.

Prediction of Soc in Calcic Chernozem in the Steppe Zone of Ukraine Using Brightness and Colour Indicators

Abstract Soil organic carbon (SOC) is an important component of any soil which determines many of its properties. Nowadays, more and more attention is being paid to the SOC content determination in soils by not using the conventional, time-consuming and expensive technique, but by using colour image processing of soil samples. In this case, even the camera of modern smartphones can be used as an image source, making this technique very convenient and practical. However, it is important to maintain certain standardised conditions (light intensity, light incidence angle, etc.) when capturing the images of soil samples. In our opinion, it is best to use a regular scanner for this purpose, with subsequent image processing by graphic programs (e.g., Adobe Photoshop). To increase the reliability of the colour information obtained in this way, it is desired (if possible) to use a spectrograph or a monochromator in the subsequent calculation of reflection or brightness ratios. It is these two approaches that we have implemented in our work. As a result of the experiment, the values of brightness ratios (at 480, 650 and 750 nm wavelengths and integral brightness ratio), colour indicators (the hue, saturation and value [HSV], red, green and blue [RGB], CIE L*a*b* and cyan, magenta, yellow and key [CMYK] systems) and SOC content in Calcic Chernozem samples of the steppe zone of Ukraine were obtained. Using correlation analysis of the dataset, the existence of direct (r = 0.88–0.90) and inverse close relationships (r = −0.75–0.90) between SOC, values of brightness ratios and colour indicators of the soil samples were established. This allows us to develop predictive models. Statistical analysis showed that the models were significant when they were based on the values of brightness ratios at 650 nm wavelength, integral brightness ratio, V indicator in HSV system, R, G and B indicators in RGB system, C, M and K indicators in CMYK system and L* and b* indicators in L*a*b* system. The subsequent calculation of variation coefficients showed that the largest variability was observed in SOC indicators (CV = 0.72) and slightly less variability in the K index of CMYK system and brightness ratio values at 650 nm wavelength (CV = 0.67 and 0.53, respectively). Based on this, we believe that the models y = 0.0188 + 0.0535*x (x is the value of the K index in CMYK system) and y = 5.0716 – 3.2255*log10(x) (x is the value of brightness ratio at 650 nm wavelength) were the most statistically significant and promising parameters for determining SOC content (y in these equations) in Calcic Chernozem samples of the steppe zone of Ukraine.

Assessment of a photon recollision probability based forest reflectance model in European boreal and temperate forests

We report a new version and an empirical evaluation of a forest reflectance model based on photon recollision probability (p). For the first time, a p-based approach to modeling forest reflectance was tested in a wide range of differently structured forests from different biomes. To parameterize the model, we measured forest canopy structure and spectral characteristics for 50 forest plots in four study sites spanning from boreal to temperate biomes in Europe (48°–62°N). We compared modeled forest reflectance spectra against airborne hyperspectral data at wavelengths of 450–2200 nm. Large overestimation occurred, especially in the near-infrared region, when the model was parameterized considering only leaves or needles as plant elements and assuming a Lambertian canopy. The model root mean square error (RMSE) was on average 80%, 80%, 54% for coniferous, broadleaved, and mixed forests, respectively. We suggest a new parameterization that takes into account the nadir to hemispherical reflectance ratio of the canopy and contribution of woody elements to the forest reflectance. We evaluated the new parameterization based on inversion of the model, which resulted in average RMSE of 20%, 15%, and 11% for coniferous, broadleaved, and mixed forests. The model requires only few structural parameters and the spectra of foliage, woody elements, and forest floor as input. It can be used in interpretation of multi- and hyperspectral remote sensing data, as well as in land surface and climate modeling. In general, our results also indicate that even though the foliage spectra are not dramatically different between coniferous and broadleaved forests, they can still explain a large part of reflectance differences between these forest types in the near-infrared, where sensitivity of the reflectance of dense forests to changes in the scattering properties of the foliage is high.

Characterization of irradiation effect on 5251 Al-alloy using rietveld x-ray diffraction analysis

This work aims to study irradiation doses (0, 100, 200, 400, 600 and 1000 kGy of Co60 γ-source doses) effect on 5251 Al-alloy samples using XRD analysis. The main structures of the x-ray diffraction patterns are the same, a considerable difference in the peak intensities is observed due to the grain growth associated with increasing of irradiation doses. The intensity ratio of higher reflections declares that nearly 600 kGy irradiation dose is the preferred orientation or threshold point. Microstructure characterization has been studied using x-ray Diffraction Line Profile (XDLP) analysis. Minimum crystallite size of about 0.106 μm is measured for non-irradiated sample, maximum value is observed at 600 kGy. Micro-strain decreases exponentially with increasing irradiation dose, in addition the cell parameter seems to be constant. The dislocation and defect densities reveal the same behavior as the micro-strain. The defect and dislocation density decrease exponentially with increasing of irradiation doses with maximum values of about 1.10 × 1019 cm−3 and 3.15 × 1010 cm−2 respectively obtained for non-irradiation. The variation of the stored dislocation energy due to irradiation doses reveal maximum stored dislocation energy of about 334.95 kJ m−3 for non-irradiated sample, then it is approximately kept constant with increasing of irradiation dose up to 1000 kGy.

Improved Bi-Angle Aerosol Optical Depth Retrieval Algorithm from AHI Data Based on Particle Swarm Optimization

The Advanced Himawari Imager (AHI) aboard the Himawari-8, a new generation of geostationary meteorological satellite, has high-frequency observation, which allows it to effectively capture atmospheric variations. In this paper, we have proposed an Improved Bi-angle Aerosol optical depth (AOD) retrieval Algorithm (IBAA) from AHI data. The algorithm ignores the aerosol effect at 2.3 μm and assumes that the aerosol optical depth does not change within one hour. According to the property that the reflectivity ratio K of two observations at 2.3 μm does not change with wavelength, we constructed the equation for two observations of AHI 0.47 μm band. Then Particle Swarm Optimization (PSO) was used to solve the nonlinear equation. The algorithm was applied to the AHI observations over the Chinese mainland (80°–135°E, 15°–60°N) between April and June 2019 and hourly AOD at 0.47 μm was retrieved. We validated IBAA AOD against the Aerosol Robotic Network (AERONET) sites observation, including surrounding regions as well as the Chinese mainland, and compared it with the AHI L3 V030 hourly AOD product. Validation with AERONET of 2079 matching points shows a correlation coefficient R = 0.82, root-mean-square error RMSE = 0.27, and more than 62% AOD retrieval results within the expected error of ±(0.05 + 0.2 × AODAERONET). Although IBAA does not perform very well in the case of coarse-particle aerosols, the comparison and validation demonstrate it can estimate AHI AOD with good accuracy and wide coverage over land on the whole.

Discussion on effect of material on UV reflection and its disinfection with focus on Japanese Stucco for interior wall

Research has previously shown that ultraviolet light C (UV-C) can inactivate unexpected infection. However, this type of potential disinfection is dramatically reduced for the shadow area such as under desk or medical equipment. Because the UV-C reflectance ratio is low on the general wall surfaces. We compared Stucco against the other materials to investigate whether we could improve disinfection for the shadow area. The reflectance ratios of UV-C irradiation of each material were examined, with particular attention to the rates for the author’s Modified Stucco. To evaluate the disinfection effects of the UV-C reflective lighting, colonies of E. coli and of Staphylococcus hominis were cultured in an agar media and counted over a certain time period after applying UV-C irradiation from a sterilizing lamp onto the investigation materials. The author’s Modified Stucco, produced reflectance ratios that was 11 times that of white wallpaper. This demonstrated that the UV-C reflected on the Stucco wall having optimum components and their compositions inhibited the number of E. coli and S. hominis, resulting in significantly disinfection effects on white wallpapers. The space with Modified Stucco and then irradiated by a UV-C may give a strong disinfection effect.