Metal trace elements (MTE) are among the most harmful micropollutants of natural waters. Eliminating them helps improve the quality and safety of drinking water and protect human health. In this work, we used mango ke...Metal trace elements (MTE) are among the most harmful micropollutants of natural waters. Eliminating them helps improve the quality and safety of drinking water and protect human health. In this work, we used mango kernel powder (MKP) as bioadsorbent material for removal of Cr (VI) from water. Uv-visible spectroscopy was used to monitor and quantify Cr (VI) during processing using the Beer-Lambert formula. Some parameters such as pH, mango powder, mass and contact time were optimized to determine adsorption capacity and chromium removal rate. Adsorption kinetics, equilibrium, isotherms and thermodynamic parameters such as ΔG˚, ΔH˚, and ΔS˚, as well as FTIR were studied to better understand the Cr (VI) removal process by MKP. The adsorption capacity reached 94.87 mg/g, for an optimal contact time of 30 min at 298 K. The obtained results are in accordance with a pseudo-second order Freundlich adsorption isotherm model. Finally FTIR was used to monitor the evolution of absorption bands, while Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) were used to evaluate surface properties and morphology of the adsorbent.展开更多
The China Seismo-Electromagnetic Satellite(CSES) will investigate iono-magnetospheric disturbance and will monitor the temporal stability of the inner Van Allen radiation belts.In particular,the mission aims at confir...The China Seismo-Electromagnetic Satellite(CSES) will investigate iono-magnetospheric disturbance and will monitor the temporal stability of the inner Van Allen radiation belts.In particular,the mission aims at confirming the existences of a temporal correlation between the occurrence of earthquakes and the observation of electromagnetic disturbances, plasma fluctuations and anomalous fluxes of high-energy particles precipitating from the inner Van Allen belt in space.The high energy detector of the High Energy Particle Package(HEPP-H) is a payload onboard CSES and is designed for detecting electrons(2–50 MeV) and protons(20–200 MeV) in its 500 km orbit above Earth.CSES was launched in February 2018.In this paper, the instrumentation and development of the HEPP-H calorimeter are described.The calibration with beam particles(electrons and protons) is discussed in detail.展开更多
Thin films constituted of CuAlS_(2) nanoparticles deposited with various deposition velocities in single and multilayers onto silicon Si(111)substrates by thermal evaporation have been studied by lifting their structu...Thin films constituted of CuAlS_(2) nanoparticles deposited with various deposition velocities in single and multilayers onto silicon Si(111)substrates by thermal evaporation have been studied by lifting their structural and thermal properties.Thermal properties of Si(111)and Si(111)/CuAlS_(2) structures are determined by using the photothermal deflection technique by comparing experimental and theoretical signals.We succeed in extracting the thermal conductivity,the thermal diffusivity,and the electron free mean path of these deposited chalcogenide layers.For the multilayers,the obtained values of the thermal conductivity are in good agreement with the theoretical data.展开更多
A spectrofluorimetric method for the direct analysis of carbendazim [methyl 2-benzimidazole carbamate (MBC)] fungicide and its metabolite 2-aminobenzimidazole (2-AB) in natural waters is described. Very low limit of d...A spectrofluorimetric method for the direct analysis of carbendazim [methyl 2-benzimidazole carbamate (MBC)] fungicide and its metabolite 2-aminobenzimidazole (2-AB) in natural waters is described. Very low limit of detection (LOD) and limit of quantification (LOQ) values of 0.002 - 0.06 ng/mL and 0.006 - 0.2 ng/mL, respectively, were determined by spectrofluorimetric method with small relative standard deviation (RSD) values < 1%. This spectrofluorimetric method was applied to the determination of MBC and 2-AB residues in natural waters, with satisfactory recovery values of (88.5% - 119.2%).展开更多
In this paper,we present a new approach to the detection of Sea Breeze Fronts(SBF)in the Gulf of Guinea using automated methods.The study focuses on southern West Africa,where SBFs play a crucial role in local weather...In this paper,we present a new approach to the detection of Sea Breeze Fronts(SBF)in the Gulf of Guinea using automated methods.The study focuses on southern West Africa,where SBFs play a crucial role in local weather.The re-search demonstrates that the dynamic of SBFs exerts a significant influence on local weather conditions and acts as a favourable mechanism for convection.The aim of this study is to improve the effectiveness of conventional SBF de-tection techniques by applying an automated methodology through the analy-sis of images obtained by the second generation Meteosat(MSG)satellite.Our method,based on an active contour technique called morphological snake,is capable of automatically detecting the cumulus lines that are associated with SBF in a relatively short period of time using a substantial number of MSG images taken every 15 min.To delineate the SBFs and to model their inland propagation by isochrones,several regression methods were employed.Among these,the kernel-weighted local polynomial regression(kwLPR)provided the greatest accuracy in modeling the SBF propagation,with an average spatial root mean square error(RMSE)of only 0.0034˚.The SBF penetrated as far as 100 to 146.3 km inland at certain longitudes.Its average penetration along the coast is 103.17 km.The algorithm is highly robust and has a wide range of practical ap-plications,including automatic pattern recognition and dynamic imaging.Fur-thermore,it has significant potential for future research into other complex phe-nomena,such as the propagation of pollutants and other atmospheric particles.展开更多
The low energy particle detector （LEPD） is one of the main payloads onboard the China seismic electromagnetic satellite （CSES）. The detector is designed to ascertain space electrons （0.1–10 MeV） and protons （2...The low energy particle detector （LEPD） is one of the main payloads onboard the China seismic electromagnetic satellite （CSES）. The detector is designed to ascertain space electrons （0.1–10 MeV） and protons （2–50 MeV）. It has the capability of identifying the electrons and protons, to measure the energy spectrum and the incident angle of the particles. The LEPD is made up of a silicon tracker system, a CsI （Tl） mini-calorimeter, an anti-coincidence system made by plastic scintillator, as well as electronics and a data acquisition system （DAQ）. The tracker is also a kind of E-E telescope; it consists of two layers of double-sided silicon strip detectors （DSSD）. The signals emerging from the silicon tracker can be read out by two pieces of application specific integrated circuit （ASIC）, which also can generate an event trigger for the LEPD. The functions of the DSSD system in the LEPD for charged particles were tested by 241Am @5.486 MeV α particles. The results show that the DSSD system works well, and has high performance to detect charged particles and measure the position of incident particles.展开更多
The fact that traditional semiconductors have almost reached their performance limits in high power applications,is leading to failure in high power devices.This failure results from self-heating effects,leading to hi...The fact that traditional semiconductors have almost reached their performance limits in high power applications,is leading to failure in high power devices.This failure results from self-heating effects,leading to higher temperature and a breakdown of the electrical contact.The good thermal and mechanical properties of 4 H-SiC and Ti_(3)SiC_(2) and their good performance at high temperatures make them good candidates for high power applications.In order to improve the performance of electrical contacts,a thermo-mechanical simulation was carried out using the finite element method to study the self-heating effects in a high power PN diode made of a 4 H-SiC substrate with a Ti_(3)SiC_(2) electrical contact and Al_(3)Ti metallization.The three-dimensional model took into account the temperature dependency of several thermal and mechanical properties of the different materials to improve calculation accuracy.To simulate the self-heating,the power loss in the diode was calculated from the corresponding direct I-V characteristic.In addition,the interfacial thermal resistances(ITR)between the different layers were varied and studied in the thermo-mechanical investigation,in sequence to determine their effects on the heat dissipation and the resulting stresses in the model.The results show that for realistic ITR values,the ITR barely affects heat diffusion mechanical stresses of the model.Whereas,ITR may cause serious problem to the functionality and the efficiency of some electronic components.On the other hand,extremely large ITR leads to a decrease in the thermal stress in the diode.Good control on the ITR may help to improve the performance of high-power devices in the future,in addition to providing more efficient electrical contacts.展开更多
文摘Metal trace elements (MTE) are among the most harmful micropollutants of natural waters. Eliminating them helps improve the quality and safety of drinking water and protect human health. In this work, we used mango kernel powder (MKP) as bioadsorbent material for removal of Cr (VI) from water. Uv-visible spectroscopy was used to monitor and quantify Cr (VI) during processing using the Beer-Lambert formula. Some parameters such as pH, mango powder, mass and contact time were optimized to determine adsorption capacity and chromium removal rate. Adsorption kinetics, equilibrium, isotherms and thermodynamic parameters such as ΔG˚, ΔH˚, and ΔS˚, as well as FTIR were studied to better understand the Cr (VI) removal process by MKP. The adsorption capacity reached 94.87 mg/g, for an optimal contact time of 30 min at 298 K. The obtained results are in accordance with a pseudo-second order Freundlich adsorption isotherm model. Finally FTIR was used to monitor the evolution of absorption bands, while Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) were used to evaluate surface properties and morphology of the adsorbent.
基金supported by the National Natural Science Foundation of China(Grant Nos.11405192 and 11775251)
文摘The China Seismo-Electromagnetic Satellite(CSES) will investigate iono-magnetospheric disturbance and will monitor the temporal stability of the inner Van Allen radiation belts.In particular,the mission aims at confirming the existences of a temporal correlation between the occurrence of earthquakes and the observation of electromagnetic disturbances, plasma fluctuations and anomalous fluxes of high-energy particles precipitating from the inner Van Allen belt in space.The high energy detector of the High Energy Particle Package(HEPP-H) is a payload onboard CSES and is designed for detecting electrons(2–50 MeV) and protons(20–200 MeV) in its 500 km orbit above Earth.CSES was launched in February 2018.In this paper, the instrumentation and development of the HEPP-H calorimeter are described.The calibration with beam particles(electrons and protons) is discussed in detail.
文摘Thin films constituted of CuAlS_(2) nanoparticles deposited with various deposition velocities in single and multilayers onto silicon Si(111)substrates by thermal evaporation have been studied by lifting their structural and thermal properties.Thermal properties of Si(111)and Si(111)/CuAlS_(2) structures are determined by using the photothermal deflection technique by comparing experimental and theoretical signals.We succeed in extracting the thermal conductivity,the thermal diffusivity,and the electron free mean path of these deposited chalcogenide layers.For the multilayers,the obtained values of the thermal conductivity are in good agreement with the theoretical data.
基金the Service of Cooperation and Cultural Action of the Embassy of France for financial support
文摘A spectrofluorimetric method for the direct analysis of carbendazim [methyl 2-benzimidazole carbamate (MBC)] fungicide and its metabolite 2-aminobenzimidazole (2-AB) in natural waters is described. Very low limit of detection (LOD) and limit of quantification (LOQ) values of 0.002 - 0.06 ng/mL and 0.006 - 0.2 ng/mL, respectively, were determined by spectrofluorimetric method with small relative standard deviation (RSD) values < 1%. This spectrofluorimetric method was applied to the determination of MBC and 2-AB residues in natural waters, with satisfactory recovery values of (88.5% - 119.2%).
基金the BMBF(“Bundesministerium für Bildung und Forschung”)for funding the PhD research of Thomas D.Allagbe through FURIFLOOD Research Project(“Current and future risks of urban and rural flooding in West Africa”,Grant No.:01LG2086B)under the West African Science Service Center on Climate Change and Adapted Land Use(WASCAL)programWe would like to thank the advisors and examiners for their valuable contributions and comments,in particular Prof Andreas H.Fink and Dr Marlon Maranan from Karlsruhe Institute of Technology(Germany),and the anonymous researchers of FURIFLOOD.
文摘In this paper,we present a new approach to the detection of Sea Breeze Fronts(SBF)in the Gulf of Guinea using automated methods.The study focuses on southern West Africa,where SBFs play a crucial role in local weather.The re-search demonstrates that the dynamic of SBFs exerts a significant influence on local weather conditions and acts as a favourable mechanism for convection.The aim of this study is to improve the effectiveness of conventional SBF de-tection techniques by applying an automated methodology through the analy-sis of images obtained by the second generation Meteosat(MSG)satellite.Our method,based on an active contour technique called morphological snake,is capable of automatically detecting the cumulus lines that are associated with SBF in a relatively short period of time using a substantial number of MSG images taken every 15 min.To delineate the SBFs and to model their inland propagation by isochrones,several regression methods were employed.Among these,the kernel-weighted local polynomial regression(kwLPR)provided the greatest accuracy in modeling the SBF propagation,with an average spatial root mean square error(RMSE)of only 0.0034˚.The SBF penetrated as far as 100 to 146.3 km inland at certain longitudes.Its average penetration along the coast is 103.17 km.The algorithm is highly robust and has a wide range of practical ap-plications,including automatic pattern recognition and dynamic imaging.Fur-thermore,it has significant potential for future research into other complex phe-nomena,such as the propagation of pollutants and other atmospheric particles.
基金Supported by China 863 High Technology Development Program "Study on identification and Quantitative Retriveval of the Lunar Surface Composition" (2010AA122203)
文摘The low energy particle detector （LEPD） is one of the main payloads onboard the China seismic electromagnetic satellite （CSES）. The detector is designed to ascertain space electrons （0.1–10 MeV） and protons （2–50 MeV）. It has the capability of identifying the electrons and protons, to measure the energy spectrum and the incident angle of the particles. The LEPD is made up of a silicon tracker system, a CsI （Tl） mini-calorimeter, an anti-coincidence system made by plastic scintillator, as well as electronics and a data acquisition system （DAQ）. The tracker is also a kind of E-E telescope; it consists of two layers of double-sided silicon strip detectors （DSSD）. The signals emerging from the silicon tracker can be read out by two pieces of application specific integrated circuit （ASIC）, which also can generate an event trigger for the LEPD. The functions of the DSSD system in the LEPD for charged particles were tested by 241Am @5.486 MeV α particles. The results show that the DSSD system works well, and has high performance to detect charged particles and measure the position of incident particles.
文摘The fact that traditional semiconductors have almost reached their performance limits in high power applications,is leading to failure in high power devices.This failure results from self-heating effects,leading to higher temperature and a breakdown of the electrical contact.The good thermal and mechanical properties of 4 H-SiC and Ti_(3)SiC_(2) and their good performance at high temperatures make them good candidates for high power applications.In order to improve the performance of electrical contacts,a thermo-mechanical simulation was carried out using the finite element method to study the self-heating effects in a high power PN diode made of a 4 H-SiC substrate with a Ti_(3)SiC_(2) electrical contact and Al_(3)Ti metallization.The three-dimensional model took into account the temperature dependency of several thermal and mechanical properties of the different materials to improve calculation accuracy.To simulate the self-heating,the power loss in the diode was calculated from the corresponding direct I-V characteristic.In addition,the interfacial thermal resistances(ITR)between the different layers were varied and studied in the thermo-mechanical investigation,in sequence to determine their effects on the heat dissipation and the resulting stresses in the model.The results show that for realistic ITR values,the ITR barely affects heat diffusion mechanical stresses of the model.Whereas,ITR may cause serious problem to the functionality and the efficiency of some electronic components.On the other hand,extremely large ITR leads to a decrease in the thermal stress in the diode.Good control on the ITR may help to improve the performance of high-power devices in the future,in addition to providing more efficient electrical contacts.
