Spectral Characteristics of Soil Types in Northwestern Jordan Considering Iron Oxides Effects and Colors

Author(s):  
Wahib Sahwan ◽  
Bernhard Lucke ◽  
Tobias Sprafke ◽  
Kim André Vanselow ◽  
Rupert Bäumler
Author(s):  
Songyan Li ◽  
Meng Li ◽  
Guoxi Wang ◽  
Xiaolei Sun ◽  
Beidou Xi ◽  
...  

Abstract Background Exploration of composition and chemical characteristics of soil dissolved organic matter (DOM) is significant to understand its biogeochemical role in terrestrial ecosystems. A total of 43 cropped and 16 natural soils (0–20 cm) under four soil types (cinnamon, chernozem, red and paddy soils) across China were collected to investigate the spectral characteristics of DOM using UV–Vis and 3D-EEM spectroscopy. Results The chernozem soils exhibited the highest aromaticity and humification degree among the four soil types. Ranges of biological index (BIX, 0.53–1.17) and fluorescence index (FI, 1.55–2.10) were found in the investigated DOM, showing joint contribution from allochthonous and autochthonous sources. Higher BIX and FI in the DOM of the paddy and red soils indicated a greater reliance on autochthonous sources for these two soil types. The cropped soils showed no significant differences in chemical characteristics and sources from the natural soils for the cinnamon, chernozem and red soils. UVA (16.2–47.9%) and UVC fulvic-like substances (15.4–40.5%) were the prevailing DOM components, which were highest in the chernozem soils. Additionally, the cropped soils had a higher proportion of humic-like substances than the natural soils in the DOM. Conclusions Both soil type and land-use strongly affected the chemical characteristics of soil DOM, but only soil type had an impact on the DOM composition for the collected soils. These findings may contribute to the prediction of the biochemical behavior of soil DOM under different soil types and land-uses in terrestrial ecosystems.


2011 ◽  
Vol 65 (10) ◽  
pp. 1151-1161 ◽  
Author(s):  
Mark Baron ◽  
Jose Gonzalez-Rodriguez ◽  
Ruth Croxton ◽  
Rafael Gonzalez ◽  
Rebeca Jimenez-Perez

2020 ◽  
Vol 44 (21) ◽  
pp. 8710-8717
Author(s):  
André L. D. Lima ◽  
Humberto V. Fajardo ◽  
André E. Nogueira ◽  
Márcio C. Pereira ◽  
Luiz C. A. Oliveira ◽  
...  

Nb-peroxo@iron oxides show high selectivity and activity in aniline conversion to azoxybenzene.


1952 ◽  
Vol 44 (3) ◽  
pp. 449-449
Author(s):  
C DeWitt ◽  
M Livingood ◽  
K Miller
Keyword(s):  

1996 ◽  
Vol 93 ◽  
pp. 1509-1524 ◽  
Author(s):  
C Courty ◽  
H Buscail ◽  
JP Larpin
Keyword(s):  

Author(s):  
В. В. Руденко ◽  
И. В. Калужинов ◽  
Н. А. Андрущенко

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of noise reduction from UAVs urgent both from the point of view of acoustic imperceptibility and ecology.The aim of the work is to determine a set of methods that help to reduce the visibility of UAVs in the acoustic range. It is shown that the main source of noise from the UAV on the ground is the power plant, which includes the engine and the propeller. The parameters of the power plants influencing the processes that determine the acoustic signature of the UAV were investigated. A comprehensive analysis of the factors affecting visibility was carried out. The power plants include two-stroke and four-stroke engines, internal combustion and two-blade propellers. The use of silencers on the exhaust of the internal combustion engine was considered. The spectral characteristics of the acoustic fields of the propeller-driven power plants for the operating sample of the UAV "Eco" were obtained. The measurements were carried out in one-third octave and 1/48 octave frequency bands under static conditions. The venue is the KhAI airfield. Note that the propellers that were part of the power plants operated at Reynolds numbers (Re0,75<2*105), which can significantly affect its aerodynamic and acoustic characteristics. It is shown that when choosing a UAV control system, one should take into account the fact that two-stroke piston engines are the dominant source in the noise of propeller-driven control systems in the absence of a hood and mufflers in the intake and exhaust tracts. The use of a four-stroke internal combustion engine significantly reduces the noise of the control system. In the general case, the position of the boundaries of the zone of acoustic visibility of a UAV at the location of the observer is determined by the ratio between the intensity of acoustic radiation perceived by the observer from the UAV and the intensity of sound corresponding to the natural acoustic background and depends on the degree of manifestation of acoustic effects accompanying the propagation of sound in a turbulent atmosphere - the refraction of sound waves. Absorption and dissipation of acoustic energy. The calculation and comparison of the UAV detection range was carried out taking into account the existing natural maskers.The results of experimental studies are presented that allow assessing the degree of acoustic signature of the UAV. A set of measures aimed at reducing the intensity of the acoustic signature of the UAV in various regions of the radiation spectrum has been determined.


Sign in / Sign up

Export Citation Format

Share Document