We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using K...We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using Ka time-resolved imaging,it is found that in the case of massive targets,the hot-electron generation follows the laser pulse intensity with a short delay needed for favorable plasma formation.Conversely,a significant delay in the x-ray emission compared with the laser pulse intensity profile is observed in the case of thin targets.Theoretical analysis and numerical simulations suggest that this is related to radiation preheating of the foil and the increase in hot-electron lifetime in a hot expanding plasma.展开更多
This study proposes an advanced leaching method using organic acids to recover rare earth elements(REEs)from NdFeB permanent magnets from end-of-life computers hard disk drives(HDDs).The end-oflife HDDs were first dis...This study proposes an advanced leaching method using organic acids to recover rare earth elements(REEs)from NdFeB permanent magnets from end-of-life computers hard disk drives(HDDs).The end-oflife HDDs were first dismantled in order to recover NdFeB magnets,which were then thermally demagnetized at 350℃during 30 min before crushing in a ball mill under inert atmosphere.Scanning electron microscopy/energy dispersive X-ray spectroscopy(SEM/EDS)analyses performed on the NdFeB magnets show the heterogeneous structure containing the major matric phase Nd_(2)Fe_(14)B and the REEsrich phase containing Nd and Pr oxides.Additionally,X-ray diffraction(XRD)and Mossbauer spectroscopy(MS)analyses on the ground NdFeB magnet show that grinding NdFeB magnets under inert atmosphere helps to minimize its oxidation.Chemical analysis shows that the composition of the ground sample is Nd:22.8 wt%,Pr:3.3 wt%,Dy:1.2 wt%,Fe:62.6 wt%,Co:1.5 wt%,B:0.9 wt%,Ni:0.6 wt%.Diagrams of speciation and equilibrium phases(E_(h) vs.pH)were calculated to determine the predominance of the formed species in the REEs-organic acids systems.The influence of the organic acid type(acetic acid,formic acid,citric acid and tartaric acid),the acid concentration(10 vol%,up to saturation),and the solid/liquid(S/L)ratio(0.5%-10%)on NdFeB magnets leaching was investigated employing an optimal experimental design conceived by the statistical software JMP.Acetic acid(CH_(3)COOH)shows the highest leaching performance of REEs,allowing leaching yields over 90%for Nd,Dy and Pr in the acid concentration range of 1.6-10 mol/L and the S/L ratio range of 0.5%-5%at a temperature of 60℃.The results presented in this investigation suggest that REEs can be recovered from magnets of end-of-life HDDs using an eco-friendly method assisted by organic acids.展开更多
Hydrogen absorption and desorption characteristics for high coercivity NdDyFeCoNbCuB sintered bulk magnets were studied, by differential scanning calorimetry （DSC） measurement and hydrogenation kinetics measurement....Hydrogen absorption and desorption characteristics for high coercivity NdDyFeCoNbCuB sintered bulk magnets were studied, by differential scanning calorimetry （DSC） measurement and hydrogenation kinetics measurement. The DSC measurements showed that hydrogenation of Nd-rich phase occurred in the temperature range of 40-185 ℃, hydrogenation of the tetragonal （Ф） phase in the temperature range of 185-220 ℃, as well as the disproportionation of the Ф phase that occurred in a broad temperature range from around 500 to 800 ℃. The hydrogenation kinetics measurements indicated that hydrogen absorption of the bulk magnets at 50 ℃ absorbed more hydrogen than at 150 ℃, although this procedure was slower at 50 ℃ than at 150℃. This phenomenon was discussed by means of pressure-concentration-temperature （p-c-T） diagrams.展开更多
Deadlock resolution strategies based on siphon control are widely investigated.Their computational efficiency largely depends on siphon computation.Mixed-integer programming(MIP)can be utilized for the computation of ...Deadlock resolution strategies based on siphon control are widely investigated.Their computational efficiency largely depends on siphon computation.Mixed-integer programming(MIP)can be utilized for the computation of an emptiable siphon in a Petri net(PN).Based on it,deadlock resolution strategies can be designed without requiring complete siphon enumeration that has exponential complexity.Due to this reason,various MIP methods are proposed for various subclasses of PNs.This work proposes an innovative MIP method to compute an emptiable minimal siphon(EMS)for a subclass of PNs named S^(4)PR.In particular,many particular structural characteristics of EMS in S4 PR are formalized as constraints,which greatly reduces the solution space.Experimental results show that the proposed MIP method has higher computational efficiency.Furthermore,the proposed method allows one to determine the liveness of an ordinary S^(4)PR.展开更多
Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infue...Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and microstructure.In this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)technologies.Themicrostructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail.The results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase selection.In terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is presented.For the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(<10-2m s-1)and R(5.06×103?C s-1)increased,part of theα-Fe soft magnetic phase(31.7vol.%)is suppressed,and a higher volume of Nd2Fe17Bxmetastable phases(47.5 vol.%)areformed.As a result,both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties.In contrast,employing the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet.Additionally,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic characteristics.Consequently,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic performance,comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP(Nd-lean)Nd-Fe-Bpowder.展开更多
This review summarizes the recent advances on the application of ^(57)Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine st...This review summarizes the recent advances on the application of ^(57)Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce_(2)Fe_(14)B,(Ce,Nd)_(2)Fe_(14)B and MM_(2)Fe_(14)B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting öEQ of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field Bhfincreases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the ^(57)Fe Mössbauer spectrometry due to its high sensitivity. On this basis,the content, magnetic behavior, and magnetization of the REFe_(2) phase, the amorphous grain boundary(GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.展开更多
A novel statistical approach to evaluate the manufacturing quality of press coated tablets in terms of the centering of their core is presented. We also provide a formula to determine the necessary sample size. This a...A novel statistical approach to evaluate the manufacturing quality of press coated tablets in terms of the centering of their core is presented. We also provide a formula to determine the necessary sample size. This approach is applied to real data.展开更多
We introduce a new approach to image super-resolution. The idea is to use a simple wavelet-based linear interpolation scheme as our initial estimate of high-resolution image;and to intensify geometric structure in ini...We introduce a new approach to image super-resolution. The idea is to use a simple wavelet-based linear interpolation scheme as our initial estimate of high-resolution image;and to intensify geometric structure in initial estimation with an iterative projection process based on hard-thresholding scheme in a new angular multiselectivity domain. This new domain is defined by combining of laplacian pyramid and angular multiselectivity decomposition, the result is multiselective contourlets which can capture and restore adaptively and slightly better geometric structure of image. The experimental results demonstrate the effectiveness of the proposed approach.展开更多
Mobile games are gaining in popularity among students, although the factors driving engagement remain poorly understood. This study, conducted among 378 students studying for a Bachelor’s degree in Computer and Digit...Mobile games are gaining in popularity among students, although the factors driving engagement remain poorly understood. This study, conducted among 378 students studying for a Bachelor’s degree in Computer and Digital Sciences at the Université Virtuelle de Côte d’Ivoire, explores the influence of game assets and colours on player engagement. Using an online questionnaire, the study identified students’ gaming preferences and their perception of colours. The results show that the key elements most favoured by students are graphics, sound design, the game system, narrative, interactivity and accessibility. What’s more, colour plays a decisive role in their preferences and commitment to educational mobile games.展开更多
Mixed convection of heat and mass transfer in an isosceles trapezoidal cavity has been studied numerically. Constant heat flux is imposed through four outlets and the grid is insulated. The inclined walls are maintain...Mixed convection of heat and mass transfer in an isosceles trapezoidal cavity has been studied numerically. Constant heat flux is imposed through four outlets and the grid is insulated. The inclined walls are maintained in natural convection while the lower horizontal wall is adiabatic. These conditions reflect the air draft zone of the ASUTO charcoal stove. The governing two-di- mensional flow equations have been solved by using the finite difference method and Thomas’s algorithm. The investigations are conducted for different values of Richardson (R<sub>i</sub>), Reynolds number (R<sub>e</sub>) and inclination angles of sidewalls. The results are presented in terms of streamlines, isotherms, moisture contours. It was found that for Reynolds number (R<sub>e</sub>) equal to 100, the flow pattern is strongly dependent on the inclination angle and Richardson number. Thus, for high Richardson number (R<sub>i</sub>) values (10, 100), the dominance of natural convection over the flow structure decreases with the decreasing of the inclination angle of sidewalls of the cavity. For R<sub>i</sub> = 1, an optimum air draft corresponds to an inclination angle in the vicinity of 22° while for R<sub>i</sub> = 10 or 100 (in dominance of natural convection), the optimum inclination angle for air draft is in the vicinity of 15°.展开更多
Hepatic fibrosis is a pathological lesion, characterized by the progressive accumulation of extracellularmatrix （ECM） in the perisinusoidal space and it is a major problem in chronic liver diseases. Phenotypicactiva...Hepatic fibrosis is a pathological lesion, characterized by the progressive accumulation of extracellularmatrix （ECM） in the perisinusoidal space and it is a major problem in chronic liver diseases. Phenotypicactivation of hepatic stellate cells （HSC） plays a central role in the progression of hepatic fibrosis. Retardation of proliferation and clearance of activated HSCs from the injured liver is an appropriate therapeuticstrategy for the resolution and treatment of hepatic fibrosis. Clearance of activated HSCs from the injuredliver by autophagy inhibitors, proapoptotic agents and senescence inducers with the high affinity towardthe activated HSCs may be the novel therapeutic strategy for the treatment of hepatic fibrosis in the nearfuture.展开更多
Comprehensive understanding and possible control of parametric instabilities in the context of inertial confinement fusion (ICF) remains achallenging task. The details of the absorption processes and the detrimental e...Comprehensive understanding and possible control of parametric instabilities in the context of inertial confinement fusion (ICF) remains achallenging task. The details of the absorption processes and the detrimental effects of hot electrons on the implosion process require as mucheffort on the experimental side as on the theoretical and simulation side. This paper describes a proposal for experimental studies on nonlinearinteraction of intense laser pulses with a high-temperature plasma under conditions corresponding to direct-drive ICF schemes. We propose todevelop a platform for laser-plasma interaction studies based on foam targets. Parametric instabilities are sensitive to the bulk plasma temperatureand the density scale length. Foam targets are sufficiently flexible to allow control of these parameters. However, investigationsconducted on small laser facilities cannot be extrapolated in a reliable way to real fusion conditions. It is therefore necessary to performexperiments at a multi-kilojoule energy level on medium-scale facilities such asOMEGAor SG-III. An example of two-plasmon decay instabilityexcited in the interaction of two laser beams is considered.展开更多
α-MoO_3 ordered nanosheets have been synthesized under hydrothermal conditions using commercial MoO_3 and hydroquinone as structuring agent. X-ray diffraction(XRD), scanning electron microscope(SEM) and transmission ...α-MoO_3 ordered nanosheets have been synthesized under hydrothermal conditions using commercial MoO_3 and hydroquinone as structuring agent. X-ray diffraction(XRD), scanning electron microscope(SEM) and transmission electron microscopy(TEM) were used to analyse the obtained material. The conductivity mechanism of the Molybdenum ordered nanosheets has been investigated using combined complex impedance and modulus formalism.The temperature dependence of the conductivity, which was between 473 and 573 K, is very close to the Arrhenius' law, with an activation energy of 0.76 eV. However, the conductivity of the material increases with temperature. It shows a typical negative temperature coefficient resistance(NTCR) similar to that of a semiconductor. The dielectric properties of the MoO_3 compound have been studied in the temperature range of 473-573 K as well as the frequency range of 10 Hz to 13 MHz. The ac-conductivity for high frequency σac(ω)obeys the universal power law.展开更多
In order to combat the counterfeiting of drugs, adapted HPLC analytical USP methods were applied to evaluate the quality of the amoxicillin (with or without potassium clavulanate) powder for suspension sold in some Co...In order to combat the counterfeiting of drugs, adapted HPLC analytical USP methods were applied to evaluate the quality of the amoxicillin (with or without potassium clavulanate) powder for suspension sold in some Congolese markets. The adaptation has been done by modifying the column dimensions and adjusting the flow rate. According to the intended deployment of these methods in Democratic Republic of Congo (DRC), 3 factors (analyst, day and equipment) were involved in the validation step while applying the classic total error measurement approach with an accuracy profile as decision tool. Since adequate results were obtained in terms of selectivity, precision, trueness and accuracy (tolerance limits of life expectancy: ?6.0% and 3.8%) for levels of interest concentration, the methods have been considered for routine use on several samples from different provenances and collected in 4 major DRC cities. Out of 278 samples collected, 200 were eligible for analysis from which 28% were found under standards with several figures: pH failure, out of specification for amoxicillin content, absence of potassium clavulanate, physical modifications of the powders. As evidenced by these findings, medicines of low-quality continue to be a major public health problem requiring appropriate action to effectively address this problem.展开更多
In Heterogeneous Networks (HetNets), Integrating Device-to-Device communication (D2D) techniques presents as a promising solution for improving system performance by offloading traffic from heavily loaded macro cell (...In Heterogeneous Networks (HetNets), Integrating Device-to-Device communication (D2D) techniques presents as a promising solution for improving system performance by offloading traffic from heavily loaded macro cell (MC) to small cells (SCs). For instance, D2D can be used to offload traffic from heavily-loaded cells to light-loaded small cells. However, offloading new users may result in an unfair load distribution among small cells and consequently may affect the quality of service of some users. To achieve better performance and reduce blocking probability load balancing among small cells should be considered when we offload traffic from macro to small cells. In this paper, we consider a centralized offloaded relay selection scheme, in which a cellular provider can decide whether users can assist each other to relay their traffic to small cells. We propose a joint user-relay selection with dynamic load balancing scheme based on D2D communications using the Kuhn-Munkres (K-M) method. The offloading process considers the load from MC to SCs and among SCs. Compared to previous works, our simulation results show that the proposed scheme increases the number of admitted users in the system, and achieves a higher load balancing fairness index among small cells. Also, our scheme achieves a higher rate fairness index among users by adjusting the signal to interference plus noise ratio (SINR) threshold.展开更多
The physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created ...The physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created by ionization of a low-density plastic foam by four high-energy(3.2 kJ)laser beams.An interaction beam is fired with a delay permitting evaluation of the excitation of parametric instabilities at different stages of plasma evolution.Multiple diagnostics are used for plasma characterization,scattered radiation,and accelerated electrons.The experimental results are analyzed with radiation hydrodynamic simulations that take account of foam ionization and homogenization.The measured level of stimulated Raman scattering is almost one order of magnitude larger than that measured in experiments with gasbags and hohlraums on the same installation,possibly because of a greater plasma density.Notable amplification is achieved in high-intensity speckles,indicating the importance of implementing laser temporal smoothing techniques with a large bandwidth for controlling laser propagation and absorption.展开更多
Chronic and potential non-healing wounds are a great challenge for patients, physicians, and wound care professionals and the health system. A balanced nutrition intake is essential for health as well as a speedy reco...Chronic and potential non-healing wounds are a great challenge for patients, physicians, and wound care professionals and the health system. A balanced nutrition intake is essential for health as well as a speedy recovery of such wounds. The study objective was to compare chronic wound inpatients supplemented with food nutrient content with outpatients with their usual intake in a cross-sectional study. Patients’ food samples were taken for chemical analyses. The protein, beta-carotene, sodium, magnesium, manganese, and potassium content prove statistically significant differences. Outpatients’ diets are more diversified than inpatients’ diets, and supplementation diet richest in beta-carotene and in protein. Outpatients have better dietary diversity than those who were hospitalized. The result provides insights of supplementary food as critical issues pertaining to chronic wounds management. However, analyzing bioavailability of nutrient on patients’ blood may provide more knowledge in the appropriate integrated wound management.展开更多
It has been reported that the host of SARS-CoV-2 can be extremely wide due to the conservation of angiotensin converting enzyme 2 in mammals[1].Several studies have reported natural or experimental infection with SARS...It has been reported that the host of SARS-CoV-2 can be extremely wide due to the conservation of angiotensin converting enzyme 2 in mammals[1].Several studies have reported natural or experimental infection with SARS-CoV-2 in pets,farm and captive wild animals[2-4].However,to the best of our knowledge,there was no published study assessing virus circulation among domestic or captive animals in Central,West and East Africa.In this study,we assessed the presence and circulation of SARS-CoV-2 or other betacoronaviruses in pets,livestock and animals kept in captivity in conservation centers in Haut-Ogoouéprovince,southeastern Gabon.展开更多
This work focuses on the modeling and evaluation of water resources in complex aquifer systems and the use of scarce data. The modeling work is developed based on the GLUE (Generalized Likelihood Uncertainty Estimatio...This work focuses on the modeling and evaluation of water resources in complex aquifer systems and the use of scarce data. The modeling work is developed based on the GLUE (Generalized Likelihood Uncertainty Estimation) method. This method is still little used in hydrogeology, although its applications in other disciplines such as hydrology proved quite efficient. The study site, located in the Republic of Djibouti (Horn of Africa), is represented by the volcanic massif of Goda. The hydraulic properties of this massif are highly heterogeneous since they are associated with fracturing and weathering of the geological formations. The data are too few to enable a conventional modeling approach of this volcanic system. The implementation of the GLUE method in a numerical groundwater flow model allowed developing a stochastic analysis of the spatial distribution of the hydraulic conductivity and the recharge modalities of this complex volcanic system. The hydraulic conductivities range from 10-6 to 10-8 m·s-1 for the basalt and the rhyolite formations (values are yet generally lower for rhyolites) and are higher than 5 × 10-7 for the sedimentary formations. In addition, considering diffuse recharge as the main mechanism by which the precipitation reaches the aquifer results in more consistent groundwater head simulations than considering only indirect recharge. The average recharge amount estimated for the Goda aquifer system is 28 mm·yr-1. The results led to a numerical representation of this system, with the least uncertainty. This model was able to estimate the available water resources of this system. This result is important because the Goda system supplies water to the city of Tadjourah. Assessment of available resources is vital for the future development of this city. From a methodological point of view, the GLUE method proved very promising for water resources assessment in complex hydrogeological systems for which little data are available.展开更多
基金funding via EUROfusion Enabling research Project No.AWP21-ENR-01-CEA-02“Advancing Shock Ignition for Direct-Drive Inertial Fusion,”the framework of the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No.101052200-EUROfusion)+2 种基金the Czech Ministry of Education,Youth and Sports (CMEYS) for funding the operation of the PALS facility (Grant No.LM2023068)the EuroHPC Joint Undertaking for awarding access to Karolina at IT4Innovations (VSB-TU),Czechia under Project No.EHPC-REG-2023R02-006(DD-23-157)the Ministry of Education,Youth and Sports of the Czech Republic through e-INFRA CZ (Grant No.ID:90140)
文摘We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using Ka time-resolved imaging,it is found that in the case of massive targets,the hot-electron generation follows the laser pulse intensity with a short delay needed for favorable plasma formation.Conversely,a significant delay in the x-ray emission compared with the laser pulse intensity profile is observed in the case of thin targets.Theoretical analysis and numerical simulations suggest that this is related to radiation preheating of the foil and the increase in hot-electron lifetime in a hot expanding plasma.
基金Project supported by the Occitanie region(RETREAt project-ALDOCT 000443)the French geological survey(BRGM)。
文摘This study proposes an advanced leaching method using organic acids to recover rare earth elements(REEs)from NdFeB permanent magnets from end-of-life computers hard disk drives(HDDs).The end-oflife HDDs were first dismantled in order to recover NdFeB magnets,which were then thermally demagnetized at 350℃during 30 min before crushing in a ball mill under inert atmosphere.Scanning electron microscopy/energy dispersive X-ray spectroscopy(SEM/EDS)analyses performed on the NdFeB magnets show the heterogeneous structure containing the major matric phase Nd_(2)Fe_(14)B and the REEsrich phase containing Nd and Pr oxides.Additionally,X-ray diffraction(XRD)and Mossbauer spectroscopy(MS)analyses on the ground NdFeB magnet show that grinding NdFeB magnets under inert atmosphere helps to minimize its oxidation.Chemical analysis shows that the composition of the ground sample is Nd:22.8 wt%,Pr:3.3 wt%,Dy:1.2 wt%,Fe:62.6 wt%,Co:1.5 wt%,B:0.9 wt%,Ni:0.6 wt%.Diagrams of speciation and equilibrium phases(E_(h) vs.pH)were calculated to determine the predominance of the formed species in the REEs-organic acids systems.The influence of the organic acid type(acetic acid,formic acid,citric acid and tartaric acid),the acid concentration(10 vol%,up to saturation),and the solid/liquid(S/L)ratio(0.5%-10%)on NdFeB magnets leaching was investigated employing an optimal experimental design conceived by the statistical software JMP.Acetic acid(CH_(3)COOH)shows the highest leaching performance of REEs,allowing leaching yields over 90%for Nd,Dy and Pr in the acid concentration range of 1.6-10 mol/L and the S/L ratio range of 0.5%-5%at a temperature of 60℃.The results presented in this investigation suggest that REEs can be recovered from magnets of end-of-life HDDs using an eco-friendly method assisted by organic acids.
文摘Hydrogen absorption and desorption characteristics for high coercivity NdDyFeCoNbCuB sintered bulk magnets were studied, by differential scanning calorimetry （DSC） measurement and hydrogenation kinetics measurement. The DSC measurements showed that hydrogenation of Nd-rich phase occurred in the temperature range of 40-185 ℃, hydrogenation of the tetragonal （Ф） phase in the temperature range of 185-220 ℃, as well as the disproportionation of the Ф phase that occurred in a broad temperature range from around 500 to 800 ℃. The hydrogenation kinetics measurements indicated that hydrogen absorption of the bulk magnets at 50 ℃ absorbed more hydrogen than at 150 ℃, although this procedure was slower at 50 ℃ than at 150℃. This phenomenon was discussed by means of pressure-concentration-temperature （p-c-T） diagrams.
基金supported in part by Zhejiang Provincial Key Research and Development Program(2018C01084)Zhejiang Natural Science Foundation(LQ20F020009)Zhejiang Gongshang University,Zhejiang Provincial Key Laboratory of New Network Standards and Technologies(2013E10012)。
文摘Deadlock resolution strategies based on siphon control are widely investigated.Their computational efficiency largely depends on siphon computation.Mixed-integer programming(MIP)can be utilized for the computation of an emptiable siphon in a Petri net(PN).Based on it,deadlock resolution strategies can be designed without requiring complete siphon enumeration that has exponential complexity.Due to this reason,various MIP methods are proposed for various subclasses of PNs.This work proposes an innovative MIP method to compute an emptiable minimal siphon(EMS)for a subclass of PNs named S^(4)PR.In particular,many particular structural characteristics of EMS in S4 PR are formalized as constraints,which greatly reduces the solution space.Experimental results show that the proposed MIP method has higher computational efficiency.Furthermore,the proposed method allows one to determine the liveness of an ordinary S^(4)PR.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4600300)the National Natural Science Foundation of China(No.U22A20189,52175364)the China Scholarship Council(Grant No.202206290134)。
文摘Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and microstructure.In this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)technologies.Themicrostructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail.The results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase selection.In terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is presented.For the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(<10-2m s-1)and R(5.06×103?C s-1)increased,part of theα-Fe soft magnetic phase(31.7vol.%)is suppressed,and a higher volume of Nd2Fe17Bxmetastable phases(47.5 vol.%)areformed.As a result,both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties.In contrast,employing the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet.Additionally,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic characteristics.Consequently,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic performance,comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP(Nd-lean)Nd-Fe-Bpowder.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LY20E010002,LR18E010001,and LD19E010001)the National Natural Science Foundation of China(Grant Nos.U1704253 and 51801047)+2 种基金Liaoning Revitalization Talents Program(Grant No.XLYC1807177)the Key Research and Development plan of Zhejiang Province,China(Grant No.2020C05014)Ten Thousand Talents Plan of Zhejiang Province,China(Grant No.2018R52003)。
文摘This review summarizes the recent advances on the application of ^(57)Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce_(2)Fe_(14)B,(Ce,Nd)_(2)Fe_(14)B and MM_(2)Fe_(14)B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting öEQ of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field Bhfincreases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the ^(57)Fe Mössbauer spectrometry due to its high sensitivity. On this basis,the content, magnetic behavior, and magnetization of the REFe_(2) phase, the amorphous grain boundary(GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.
文摘A novel statistical approach to evaluate the manufacturing quality of press coated tablets in terms of the centering of their core is presented. We also provide a formula to determine the necessary sample size. This approach is applied to real data.
文摘We introduce a new approach to image super-resolution. The idea is to use a simple wavelet-based linear interpolation scheme as our initial estimate of high-resolution image;and to intensify geometric structure in initial estimation with an iterative projection process based on hard-thresholding scheme in a new angular multiselectivity domain. This new domain is defined by combining of laplacian pyramid and angular multiselectivity decomposition, the result is multiselective contourlets which can capture and restore adaptively and slightly better geometric structure of image. The experimental results demonstrate the effectiveness of the proposed approach.
文摘Mobile games are gaining in popularity among students, although the factors driving engagement remain poorly understood. This study, conducted among 378 students studying for a Bachelor’s degree in Computer and Digital Sciences at the Université Virtuelle de Côte d’Ivoire, explores the influence of game assets and colours on player engagement. Using an online questionnaire, the study identified students’ gaming preferences and their perception of colours. The results show that the key elements most favoured by students are graphics, sound design, the game system, narrative, interactivity and accessibility. What’s more, colour plays a decisive role in their preferences and commitment to educational mobile games.
文摘Mixed convection of heat and mass transfer in an isosceles trapezoidal cavity has been studied numerically. Constant heat flux is imposed through four outlets and the grid is insulated. The inclined walls are maintained in natural convection while the lower horizontal wall is adiabatic. These conditions reflect the air draft zone of the ASUTO charcoal stove. The governing two-di- mensional flow equations have been solved by using the finite difference method and Thomas’s algorithm. The investigations are conducted for different values of Richardson (R<sub>i</sub>), Reynolds number (R<sub>e</sub>) and inclination angles of sidewalls. The results are presented in terms of streamlines, isotherms, moisture contours. It was found that for Reynolds number (R<sub>e</sub>) equal to 100, the flow pattern is strongly dependent on the inclination angle and Richardson number. Thus, for high Richardson number (R<sub>i</sub>) values (10, 100), the dominance of natural convection over the flow structure decreases with the decreasing of the inclination angle of sidewalls of the cavity. For R<sub>i</sub> = 1, an optimum air draft corresponds to an inclination angle in the vicinity of 22° while for R<sub>i</sub> = 10 or 100 (in dominance of natural convection), the optimum inclination angle for air draft is in the vicinity of 15°.
文摘Hepatic fibrosis is a pathological lesion, characterized by the progressive accumulation of extracellularmatrix （ECM） in the perisinusoidal space and it is a major problem in chronic liver diseases. Phenotypicactivation of hepatic stellate cells （HSC） plays a central role in the progression of hepatic fibrosis. Retardation of proliferation and clearance of activated HSCs from the injured liver is an appropriate therapeuticstrategy for the resolution and treatment of hepatic fibrosis. Clearance of activated HSCs from the injuredliver by autophagy inhibitors, proapoptotic agents and senescence inducers with the high affinity towardthe activated HSCs may be the novel therapeutic strategy for the treatment of hepatic fibrosis in the nearfuture.
基金The authors acknowledge support from the European Regional Development Fund for the following projects:HiFI(No.CZ.02.1.01/0.0/0.0/15_003/0000449),CAAS(No.CZ.02.1.01/0.0/0.0/16_019/0000778),ADONIS(No.CZ.02.1.01/0.0/0.0/16_019/0000789),and ELITAS(No.CZ.02.1.01/0.0/0.0/16_013/0001793)This work has received funding from the European Union Horizon 2020 Research and Innovation Programme under Grant Agreement No.633053(EUROfusion Project No.CfP-AWP17-IFE-CEA-01)+2 种基金Computational resources were provided by the MetaCentrum under the LM2010005 projectIT4InnovationsCentre of Excellence under the CZ.1.05/1.1.00/02.0070 and LM2011033 projectsthe ECLIPSE cluster of ELI-Beamlines.The EPOCH code was developed as part of the UK EPSRC-funded EP/G054940/1 project.
文摘Comprehensive understanding and possible control of parametric instabilities in the context of inertial confinement fusion (ICF) remains achallenging task. The details of the absorption processes and the detrimental effects of hot electrons on the implosion process require as mucheffort on the experimental side as on the theoretical and simulation side. This paper describes a proposal for experimental studies on nonlinearinteraction of intense laser pulses with a high-temperature plasma under conditions corresponding to direct-drive ICF schemes. We propose todevelop a platform for laser-plasma interaction studies based on foam targets. Parametric instabilities are sensitive to the bulk plasma temperatureand the density scale length. Foam targets are sufficiently flexible to allow control of these parameters. However, investigationsconducted on small laser facilities cannot be extrapolated in a reliable way to real fusion conditions. It is therefore necessary to performexperiments at a multi-kilojoule energy level on medium-scale facilities such asOMEGAor SG-III. An example of two-plasmon decay instabilityexcited in the interaction of two laser beams is considered.
文摘α-MoO_3 ordered nanosheets have been synthesized under hydrothermal conditions using commercial MoO_3 and hydroquinone as structuring agent. X-ray diffraction(XRD), scanning electron microscope(SEM) and transmission electron microscopy(TEM) were used to analyse the obtained material. The conductivity mechanism of the Molybdenum ordered nanosheets has been investigated using combined complex impedance and modulus formalism.The temperature dependence of the conductivity, which was between 473 and 573 K, is very close to the Arrhenius' law, with an activation energy of 0.76 eV. However, the conductivity of the material increases with temperature. It shows a typical negative temperature coefficient resistance(NTCR) similar to that of a semiconductor. The dielectric properties of the MoO_3 compound have been studied in the temperature range of 473-573 K as well as the frequency range of 10 Hz to 13 MHz. The ac-conductivity for high frequency σac(ω)obeys the universal power law.
文摘In order to combat the counterfeiting of drugs, adapted HPLC analytical USP methods were applied to evaluate the quality of the amoxicillin (with or without potassium clavulanate) powder for suspension sold in some Congolese markets. The adaptation has been done by modifying the column dimensions and adjusting the flow rate. According to the intended deployment of these methods in Democratic Republic of Congo (DRC), 3 factors (analyst, day and equipment) were involved in the validation step while applying the classic total error measurement approach with an accuracy profile as decision tool. Since adequate results were obtained in terms of selectivity, precision, trueness and accuracy (tolerance limits of life expectancy: ?6.0% and 3.8%) for levels of interest concentration, the methods have been considered for routine use on several samples from different provenances and collected in 4 major DRC cities. Out of 278 samples collected, 200 were eligible for analysis from which 28% were found under standards with several figures: pH failure, out of specification for amoxicillin content, absence of potassium clavulanate, physical modifications of the powders. As evidenced by these findings, medicines of low-quality continue to be a major public health problem requiring appropriate action to effectively address this problem.
文摘In Heterogeneous Networks (HetNets), Integrating Device-to-Device communication (D2D) techniques presents as a promising solution for improving system performance by offloading traffic from heavily loaded macro cell (MC) to small cells (SCs). For instance, D2D can be used to offload traffic from heavily-loaded cells to light-loaded small cells. However, offloading new users may result in an unfair load distribution among small cells and consequently may affect the quality of service of some users. To achieve better performance and reduce blocking probability load balancing among small cells should be considered when we offload traffic from macro to small cells. In this paper, we consider a centralized offloaded relay selection scheme, in which a cellular provider can decide whether users can assist each other to relay their traffic to small cells. We propose a joint user-relay selection with dynamic load balancing scheme based on D2D communications using the Kuhn-Munkres (K-M) method. The offloading process considers the load from MC to SCs and among SCs. Compared to previous works, our simulation results show that the proposed scheme increases the number of admitted users in the system, and achieves a higher load balancing fairness index among small cells. Also, our scheme achieves a higher rate fairness index among users by adjusting the signal to interference plus noise ratio (SINR) threshold.
基金This project was partially supported by the Advanced Research Using High Intensity Laser Produced Photons and Particles(ADONIS)project(Grant No.CZ.02.1.01/0.0/0.0/16_019/0000789)the CAAS project(Grant No.CZ.02.1.01/0.0/0.0/16_019/0000778)+3 种基金both from the European Regional Development FundThe results of the LQ1606 project were partially obtained with the financial support from the Ministry of Education,Youth and Sports as part of targeted support from the National Programme of Sustainability IIThe authors acknowledge support from the National Natural Science Foundation of China(Grant Nos.11775033,11875241,11975215,11905204,12035002)the Laser Fusion Research Center Funds for Young Talents(Grant No.RCFPD3-2019-6).
文摘The physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created by ionization of a low-density plastic foam by four high-energy(3.2 kJ)laser beams.An interaction beam is fired with a delay permitting evaluation of the excitation of parametric instabilities at different stages of plasma evolution.Multiple diagnostics are used for plasma characterization,scattered radiation,and accelerated electrons.The experimental results are analyzed with radiation hydrodynamic simulations that take account of foam ionization and homogenization.The measured level of stimulated Raman scattering is almost one order of magnitude larger than that measured in experiments with gasbags and hohlraums on the same installation,possibly because of a greater plasma density.Notable amplification is achieved in high-intensity speckles,indicating the importance of implementing laser temporal smoothing techniques with a large bandwidth for controlling laser propagation and absorption.
文摘Chronic and potential non-healing wounds are a great challenge for patients, physicians, and wound care professionals and the health system. A balanced nutrition intake is essential for health as well as a speedy recovery of such wounds. The study objective was to compare chronic wound inpatients supplemented with food nutrient content with outpatients with their usual intake in a cross-sectional study. Patients’ food samples were taken for chemical analyses. The protein, beta-carotene, sodium, magnesium, manganese, and potassium content prove statistically significant differences. Outpatients’ diets are more diversified than inpatients’ diets, and supplementation diet richest in beta-carotene and in protein. Outpatients have better dietary diversity than those who were hospitalized. The result provides insights of supplementary food as critical issues pertaining to chronic wounds management. However, analyzing bioavailability of nutrient on patients’ blood may provide more knowledge in the appropriate integrated wound management.
基金supported by the Centre Interdisciplinaire de Recherches Médicales de Franceville.
文摘It has been reported that the host of SARS-CoV-2 can be extremely wide due to the conservation of angiotensin converting enzyme 2 in mammals[1].Several studies have reported natural or experimental infection with SARS-CoV-2 in pets,farm and captive wild animals[2-4].However,to the best of our knowledge,there was no published study assessing virus circulation among domestic or captive animals in Central,West and East Africa.In this study,we assessed the presence and circulation of SARS-CoV-2 or other betacoronaviruses in pets,livestock and animals kept in captivity in conservation centers in Haut-Ogoouéprovince,southeastern Gabon.
文摘This work focuses on the modeling and evaluation of water resources in complex aquifer systems and the use of scarce data. The modeling work is developed based on the GLUE (Generalized Likelihood Uncertainty Estimation) method. This method is still little used in hydrogeology, although its applications in other disciplines such as hydrology proved quite efficient. The study site, located in the Republic of Djibouti (Horn of Africa), is represented by the volcanic massif of Goda. The hydraulic properties of this massif are highly heterogeneous since they are associated with fracturing and weathering of the geological formations. The data are too few to enable a conventional modeling approach of this volcanic system. The implementation of the GLUE method in a numerical groundwater flow model allowed developing a stochastic analysis of the spatial distribution of the hydraulic conductivity and the recharge modalities of this complex volcanic system. The hydraulic conductivities range from 10-6 to 10-8 m·s-1 for the basalt and the rhyolite formations (values are yet generally lower for rhyolites) and are higher than 5 × 10-7 for the sedimentary formations. In addition, considering diffuse recharge as the main mechanism by which the precipitation reaches the aquifer results in more consistent groundwater head simulations than considering only indirect recharge. The average recharge amount estimated for the Goda aquifer system is 28 mm·yr-1. The results led to a numerical representation of this system, with the least uncertainty. This model was able to estimate the available water resources of this system. This result is important because the Goda system supplies water to the city of Tadjourah. Assessment of available resources is vital for the future development of this city. From a methodological point of view, the GLUE method proved very promising for water resources assessment in complex hydrogeological systems for which little data are available.
