Winter jujube(Ziziphus jujuba'Dongzao')is greatly appreciated by consumers for its excellent quality,but brand infringement frequently occurs in the market.Here,we first determined a total of 38 elements in 16...Winter jujube(Ziziphus jujuba'Dongzao')is greatly appreciated by consumers for its excellent quality,but brand infringement frequently occurs in the market.Here,we first determined a total of 38 elements in 167 winter jujube samples from the main winter jujube producing areas of China by inductively coupled plasma mass spectrometer(ICP-MS).As a result,16 elements(Mg,K,Mn,Cu,Zn,Mo,Ba,Be,As,Se,Cd,Sb,Ce,Er,Tl,and Pb)exhibited significant differences in samples from different producing areas.Supervised linear discriminant analysis(LDA)and orthogonal projection to latent structures discriminant analysis(OPLS-DA)showed better performance in identifying the origin of samples than unsupervised principal component analysis(PCA).LDA and OPLS-DA had a mean identification accuracy of 87.84 and 94.64%in the testing set,respectively.By using the multilayer perceptron(MLP)and C5.0,the prediction accuracy of the models could reach 96.36 and 91.06%,respectively.Based on the above four chemometric methods,Cd,Tl,Mo and Se were selected as the main variables and principal markers for the origin identification of winter jujube.Overall,this study demonstrates that it is practical and precise to identify the origin of winter jujube through multi-element fingerprint analysis with chemometrics,and may also provide reference for establishing the origin traceability system of other fruits.展开更多
A multivariate statistical analysis was performed on multi-element soil geochemical data from the Koda Hill-Bulenga gold prospects in the Wa-Lawra gold belt, northwest Ghana. The objectives of the study were to define...A multivariate statistical analysis was performed on multi-element soil geochemical data from the Koda Hill-Bulenga gold prospects in the Wa-Lawra gold belt, northwest Ghana. The objectives of the study were to define gold relationships with other trace elements to determine possible pathfinder elements for gold from the soil geochemical data. The study focused on seven elements, namely, Au, Fe, Pb, Mn, Ag, As and Cu. Factor analysis and hierarchical cluster analysis were performed on the analyzed samples. Factor analysis explained 79.093% of the total variance of the data through three factors. This had the gold factor being factor 3, having associations of copper, iron, lead and manganese and accounting for 20.903% of the total variance. From hierarchical clustering, gold was also observed to be clustering with lead, copper, arsenic and silver. There was further indication that, gold concentrations were lower than that of its associations. It can be inferred from the results that, the occurrence of gold and its associated elements can be linked to both primary dispersion from underlying rocks and secondary processes such as lateritization. This data shows that Fe and Mn strongly associated with gold, and alongside Pb, Ag, As and Cu, these elements can be used as pathfinders for gold in the area, with ferruginous zones as targets.展开更多
Energetic structural materials(ESMs)are a new type of structural materials with bearing and damage characteristics.In this work the microstructure,mechanical properties and energy release characteristics of multi-elem...Energetic structural materials(ESMs)are a new type of structural materials with bearing and damage characteristics.In this work the microstructure,mechanical properties and energy release characteristics of multi-element Ti-Zr-Ta alloys with good casting performance were studied.The microstructure of the Ti_(x)ZrTa alloys gradually change from BCC+HCP to single BCC structure with the increase of Ti.While the Ti_(2)Zr_(y)Ta alloys was still uniform and single BCC structure with the increase of Zr.The evolution of microstructure and composition then greatly affect the mechanical properties and energy-release characteristics of Ti-Zr-Ta alloys.The synergistic effect of dual phase structure increases the fracture strain of Ti_(x)ZrTa(x=0.2,0.5)with the Ti content decreases,while the fracture strain of Ti_(x)ZrTa(x=2.0,3.0,4.0)gradually increase with the Ti content increases caused by the annihilation of the obstacles for dislocation movement.And as Zr content increases,the fracture strain of Ti_(2)Zr_(y)Ta alloys decrease,then the oxidation reaction rate and fragmentation degree gradually increase.The higher oxidation rate and the lager exposed oxidation area jointly leads the higher releasing energy efficiency of Ti_(x)ZrTa alloys with low Ti content and Ti_(2)Zr_(y)Ta alloys with high Zr content.展开更多
To study the effects of the gamma reflection of multi-element materials,gamma ray transport models of single-element materials,such as iron and lead,and multielement materials,such as polyethylene and ordinary concret...To study the effects of the gamma reflection of multi-element materials,gamma ray transport models of single-element materials,such as iron and lead,and multielement materials,such as polyethylene and ordinary concrete,were established in this study.Relationships among the albedo factors of the gamma photons and energies and average energy of the reflected gamma rays by material type,material thickness,incident gamma energy,and incidence angle of gamma rays were obtained by Monte Carlo simulation.The results show that the albedo factors of single-element and multi-element materials increase rapidly with an increase in the material thickness.When the thickness of the material increases to a certain value,the albedo factors do not increase further but rather tend to the saturation value.The saturation values for the albedo factors of the gamma photons,and energies and the reflection thickness are related not only to the type of material but also to the incident gamma energy and incidence angle of the gamma rays.At a given incident gamma energy,which is between 0.2 and 2.5 MeV,the smaller the effective atomic number of the multi-element material is,the higher the saturation values of the albedo factors are.The larger the incidence angle of the gamma ray is,the greater the saturation value of the gamma albedo factor,saturation reflection thickness,and average saturation energy of the reflected gamma photons are.展开更多
The paper is to integrate aerodynamic and aero-acoustic optimizatiom design of high lift devices,especially for two-element airfoils with slat.Aerodynamic analysis on flow field utilizes a high-order,high-resolution s...The paper is to integrate aerodynamic and aero-acoustic optimizatiom design of high lift devices,especially for two-element airfoils with slat.Aerodynamic analysis on flow field utilizes a high-order,high-resolution spatial differential method for large eddy simulation(LES),which can guarantee accuracy and efficiency.The aeroacoustic analysis for noise level is calculated with Ffowcs Williams-Hawkings(FW-H)integration formula.Fidelity of calculation is verified by standard models.Method of streamline-based Euler simulation(MSES)is used to obtain the aerodynamic characters.Based on the confirmation of numerical methods,detailed research has been conducted for the leading edge slat on multi-element airfoils.Various slot parameter influences on noise are analyzed.The results of the slot optimization parameters can be used in multi-element airfoil design.展开更多
A factor analysis was applied to soil geochemical data to define anomalies related to buried Pb-Zn mineralization.A favorable main factor with a strong association of the elements Zn,Cu and Pb,related to mineralizatio...A factor analysis was applied to soil geochemical data to define anomalies related to buried Pb-Zn mineralization.A favorable main factor with a strong association of the elements Zn,Cu and Pb,related to mineralization,was selected for interpretation.The median+2 MAD(median absolute deviation)method of exploratory data analysis(EDA)and C-A(concentration-area)fractal modeling were then applied to the Mahalanobis distance,as defined by Zn,Cu and Pb from the factor analysis to set the thresholds for defining multi-element anomalies.As a result,the median+2 MAD method more successfully identified the Pb-Zn mineralization than the C-A fractal model.The soil anomaly identified by the median+2 MAD method on the Mahalanobis distances defined by three principal elements(Zn,Cu and Pb)rather than thirteen elements(Co,Zn,Cu,V,Mo,Ni,Cr,Mn,Pb,Ba,Sr,Zr and Ti)was the more favorable reflection of the ore body.The identified soil geochemical anomalies were compared with the in situ economic Pb-Zn ore bodies for validation.The results showed that the median+2 MAD approach is capable of mapping both strong and weak geochemical anomalies related to buried Pb-Zn mineralization,which is therefore useful at the reconnaissance drilling stage.展开更多
Multi-element analysis in historical sites is a major issue in archaeological studies;however,this approach is almost unknown among Iranian scholars.Geochemical multi-element analysis of soil is very important to eval...Multi-element analysis in historical sites is a major issue in archaeological studies;however,this approach is almost unknown among Iranian scholars.Geochemical multi-element analysis of soil is very important to evaluate anthropogenic activities.The aim of this study consists of assessing the potential usefulness of multi-elemental soil analysis,obtained by Analytical Jena atomic absorption spectrophotometer(AAS) and ICP-MS,to recognize ancient anthropogenic features on the territory of Tappe Rivi(North Khorasan,Iran).For that purpose,a total of 80 ancient soil samples were sampled from each soil horizon and cultural layer.The research involved Fe,Al,Cd,Cu,Ni,Co,Cr,Pb,and P which trace element samples were extracted according to the International Standard ISO 11466 and phosphorus samples by Olsen method.Besides,the contamination of the soils was assessed based on enrichment factors(EFs) by using Fe as a reference element.This geochemical/archaeological approach highlights that the content of most elements in the Parthian and Sassanid ages were significantly higher than the contents of the elements in other zones,which shows that by the development of the eras,the content of the elements has also increased.Also,the accumulation of metals in the Rivi site was significantly higher than in the control area.Among the sampled zones,enrichment factor(EF) indicated that the enrichment of Cu and phosphate at the Parthian and Sassanid had the highest content.This result is important because it shows that the amount of metals and human activities are directly related to each other during different ages.展开更多
A hybrid Cartesian grid/gridless method is developed for calculating viscous flows over multi-element airfoils.The method adopts an unstructured Cartesian grid to cover most areas of the computational domain and leave...A hybrid Cartesian grid/gridless method is developed for calculating viscous flows over multi-element airfoils.The method adopts an unstructured Cartesian grid to cover most areas of the computational domain and leaves only small region adjacent to the aerodynamic bodies to be filled with the cloud of points used in the gridless methods,which results in a better combination of the computational efficiency of the Cartesian grid and the flexibility of the gridless method in handling complex geometries.The clouds of points in the local gridless region are implemented in an anisotropic way according to the features of the thin boundary layer of the viscous flows over the airfoils,and the clouds of points at the vicinity of the interface between the grid and the gridless regions are also controlled by using an adaptive refinement technique during the generation of the unstructured Cartesian grid.An implementation of the resulting hybrid method is presented for solving two-dimensional compressible Navier-Stokes(NS)equations.The simulations of the viscous flows over a RAE2822airfoil or a two-element airfoil are successfully carried out,and the obtained results agree well with the available experimental data.展开更多
Traditional distributed denial of service(DDoS)detection methods need a lot of computing resource,and many of them which are based on single element have high missing rate and false alarm rate.In order to solve the pr...Traditional distributed denial of service(DDoS)detection methods need a lot of computing resource,and many of them which are based on single element have high missing rate and false alarm rate.In order to solve the problems,this paper proposes a DDoS attack information fusion method based on CNN for multi-element data.Firstly,according to the distribution,concentration and high traffic abruptness of DDoS attacks,this paper defines six features which are respectively obtained from the elements of source IP address,destination IP address,source port,destination port,packet size and the number of IP packets.Then,we propose feature weight calculation algorithm based on principal component analysis to measure the importance of different features in different network environment.The algorithm of weighted multi-element feature fusion proposed in this paper is used to fuse different features,and obtain multi-element fusion feature(MEFF)value.Finally,the DDoS attack information fusion classification model is established by using convolutional neural network and support vector machine respectively based on the MEFF time series.Experimental results show that the information fusion method proposed can effectively fuse multi-element data,reduce the missing rate and total error rate,memory resource consumption,running time,and improve the detection rate.展开更多
A set of serf-developed apparatus for foundation physical model were utilized to conduct model tests of the multi-element composite foundation with a steel pipe pile and several gravel piles. Some load-bearing charact...A set of serf-developed apparatus for foundation physical model were utilized to conduct model tests of the multi-element composite foundation with a steel pipe pile and several gravel piles. Some load-bearing characteristics of the multi-element Composite foundation, including the curves of foundation settlement, stresses of piles, pile-soil stress ratio, and load-sharing ratio of piles and soil, were obtained to study its working performances in silty sand soil. The experimental results revealed that the multi-element composite foundation with steel pipe pile and gravel pile contributed more than the gravel pile composite foundation in improving the bearing capacity of the silty fine sand.展开更多
This investigation aimed to establish the geographical traceability of Malaysian rice by assessing the elemental composition in paddy soil.Multi-element determination in combination with a chemometric approach was app...This investigation aimed to establish the geographical traceability of Malaysian rice by assessing the elemental composition in paddy soil.Multi-element determination in combination with a chemometric approach was applied to evaluate the elemental concentrations of paddy soil from granaries cultivated with the same rice variety and to assess the relationship between elements in the soil and rice(SAR) system.A total of 29 elements(aluminum,arsenic,barium,bromine,calcium,chlorine,cobalt,chromium,cesium,europium,iron,gallium,hafnium,potassium,lanthanum,lutetium,magnesium,manganese,sodium,rubidium,antimony,scandium,samarium,thorium,titanium,uranium,vanadium,ytterbium and zinc) were successfully determined in paddy soil from Kedah,Selangor and Langkawi by neutron activation analysis.A significant difference(P < 0.05) between 18 elements in the soil samples was obtained.The chemometric approaches of principal component and linear discriminant analyses demonstrated clear discrimination and highly corrected classification(100%) of the soil samples.A high classification(98.1%) was also achieved by assessing 10 elements(aluminum,arsenic,bromine,chlorine,potassium,magnesium,manganese,sodium,rubidium and zinc),which similarly applied to rice geographical origin determination.Similar elements in SAR were also observed for differences in the pattern of correlation and bioaccumulation factor between the granaries.Furthermore,the generalized Procrustes analysis showed a 98% consensus between SAR and clear differences between the studied regions.The canonical correlation analysis demonstrated a significant correlation between the chemical profile of SAR(r~2 = 0.88,P < 0.001).Therefore,the current work model provides a reliable assessment to establish rice provenance.展开更多
Multi-element array photoelectric detector is the core devices to form a photoelectric detection target with a large field of view.This photoelectric detection target brings about the problem of uneven detection sensi...Multi-element array photoelectric detector is the core devices to form a photoelectric detection target with a large field of view.This photoelectric detection target brings about the problem of uneven detection sensitivity distribution in the detection screen.To improve the uneven detection sensitivity of this photoelectric detection target,this paper analyzes the distribution law of the uneven detection sensitivity of the photoelectric detection target using the multi-element array photoelectric detector,dissects the main factors affecting the detection sensitivity according to the photoelectric detection principle,establishes the calculation model of detection sensitivity of the photoelectric detection target in the different detection areas and proposes a method to improve the detection sensitivity by compensating the gain of each unit photoelectric detector.The analysis of simulation and experimental results show that the proposed method of photoelectric detection target can effectively improve the output signal amplitude of the projectile under the certain detection distance,in particular,the output signal amplitude of the projectile is significantly increased when the projectile passes through the detection blind area.The experimental results are consistent with the simulation results,which verify the effectiveness of the proposed improvement method.展开更多
The broad implication of the paper is to elucidate the significance of the dynamic heaving motion in the aerodynamic performance of multi-element wings,currently considered as a promising aspect for the improvement of...The broad implication of the paper is to elucidate the significance of the dynamic heaving motion in the aerodynamic performance of multi-element wings,currently considered as a promising aspect for the improvement of the aerodynamic correlation between CFD,wind tunnel and track testing in race car applications.The relationship between the varying aerodynamic forces,the vortex shedding,and the unsteady pressure field of a heaving double-element wing is investigated for a range of mean ride heights,frequencies,and amplitudes,using a two-dimensional(2D)unsteady Reynolds-averaged Navier-Stokes(URANS)approach and an overset mesh method for modelling the moving wing.The analysis of the results shows that at high frequencies,i.e.,k≥5.94 and amplitudes a/c≥0.05 the interaction of the shear vorticity between the two elements results in the generation of cohering leading and trailing edge vortices on the flap,associated to the rapid variation of thrust and downforce enhancement.Both the occurrence and intensity of these vortices are dependent upon the frequency,amplitude,and mean ride height of the heaving wing.The addition of the flap significantly alters the frequency of the shed vortices in the wake and maintains the generation of downforce for longer time in ground proximity.The comparison with the static wing provides evidence that the dynamic motion of a race car wing can be beneficial in terms of performance,or detrimental in terms of aerodynamic correlation.展开更多
A direct and simple method for the clinic muti-element determination of human blood sample by Zeeman graphite furnace atomic absorption spectropho-tometry is reported. No pretreatment of the sample is necessary other ...A direct and simple method for the clinic muti-element determination of human blood sample by Zeeman graphite furnace atomic absorption spectropho-tometry is reported. No pretreatment of the sample is necessary other than simple dilution of the sample with aqueous solution of Triton X-100. The detection limits of the elements investigated fall in the range of 0.1- 4.4 μg/L with a relative standard deviation ranging from 1.6 for zinc to 3.73% for lead. Micro liters of samples are sufficient for the determination of each element.展开更多
A model is developed for predicting the correlation between processing parameters and the technical target of double glow by applying artificial neural network (ANN). The input parameters of the neural network (NN) ar...A model is developed for predicting the correlation between processing parameters and the technical target of double glow by applying artificial neural network (ANN). The input parameters of the neural network (NN) are source voltage, workplace voltage, working pressure and distance between source electrode and workpiece. The output of the NN model is three important technical targets, namely the gross element content, the thickness of surface alloying layer and the absorption rate (the ratio of the mass loss of source materials to the increasing mass of workpiece) in the processing of double glow plasma surface alloying. The processing parameters and technical target are then used as a training set for an artificial neural network. The model is based on multiplayer feedforward neural network. A very good performance of the neural network is achieved and the calculated results are in good agreement with the experimental ones.展开更多
A new siplitter plate presure probe was developed for flow field measurements on an airfoil with slotted flap in a low speed wind tunnel with 7 by 10 ft test section. Wind tunnel tests were conducted at a Reynolds num...A new siplitter plate presure probe was developed for flow field measurements on an airfoil with slotted flap in a low speed wind tunnel with 7 by 10 ft test section. Wind tunnel tests were conducted at a Reynolds number of 2.2 million and Mach number of 0.13. The splitter plate was made of aluminum and had pressure taps on its one side. The probe can make many measurements in the plane of the plate simultaneously by using these pressure tabs. It was supported by a traversing strut in the wind tunnel and surveyed the flow field on the airfoil upper surface. Measured pressures were presented by isobars of coefficients. These isobars were connected with the pressure coefficients distributed over the airfoil. Results of splitter plate pressure probe compare well with other single-point measuring probes. However, results show that no matter how small the probe, its presence in the flow causes a disturbance, especially in the highly time-dependent separated flow regions.展开更多
Objective: based on the analysis to the elements affecting the results of China's national team in the 2010 mountain outdoor sports adventure challenge race in Abu Dhabi, some theoretical and practical basis on wh...Objective: based on the analysis to the elements affecting the results of China's national team in the 2010 mountain outdoor sports adventure challenge race in Abu Dhabi, some theoretical and practical basis on which suggestions are provided on further promoting China's mountain outdoor sports results and the competitive level are given.Subjects: athletic performance of the top six teams and China's national team in 2010 mountain outdoor sports and athletic performance;Methods: using expert interviews, reference and data, mathematical statistics, analyze the athletic performance of the top six teams and China's national team in 2010 mountain outdoor sports and athletic performance on foot and bicycle projects on class projects with the world's top mountain outdoor big gap between sports teams;Result: there are big gaps between China's mountain outdoor sports teams and foreign teams on projects like footing and bicycling;Conclusion: Although in recent years, our mountain outdoor sports performance has been greatly improved, but the large gap do exist on foot and bicycle projects. so these projects need strengthening .展开更多
Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element ...Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element airfoil.Dual-objective optimization is carried out with critical hornshaped ice accumulated during the holding phase.The optimization results show that the present optimization method significantly enhances the iced-state and clean-state performance.The optimal multi-element airfoil has a larger deflection angle and wider gap at the slat and the flap compared with the baseline configuration.The sensitivity of each design parameter is analyzed,which verifies the robustness of the design.The design is further assessed when ice is accreted during the approach and landing phases,which also shows performance improvement.展开更多
The flow around the slat cove of a two-dimensional 30P30N multi-element airfoil is investigated with time-resolved particle image velocimetry(TR-PIV)at low Reynolds number(Rec=2.41×10^(4)and 4.61×10^(4)).The...The flow around the slat cove of a two-dimensional 30P30N multi-element airfoil is investigated with time-resolved particle image velocimetry(TR-PIV)at low Reynolds number(Rec=2.41×10^(4)and 4.61×10^(4)).The effects of angle of attack(α=8°,12°,and 16°)on the mean flow characteristics and vortex dynamics are discussed.The size of the recirculation within the slat cove and the intensity of the shed vortices originating from the slat cusp shear layer are found to generally decrease as the angle of attack increases.The joint time-frequency analyses show that disturbances of different frequencies exist in the slat cusp shear layer and they trigger the different vortex shedding patterns of the slat cusp shear layer.The self-sustained oscillation within the slat cove,normally observed at high Reynolds number(Re_(c)~10^(6)),is proved to be responsible for the disturbances of different frequencies and the related vortex dynamics in the current study.展开更多
Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Sostanj, Slovenia, can efficiently retain mercury (Hg), of which most is contained in finer gypsum fractions, with concentra...Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Sostanj, Slovenia, can efficiently retain mercury (Hg), of which most is contained in finer gypsum fractions, with concentrations above 10 kg-1. The aim of this work was to identify and study the temperature stability of Hg species in gypsum by a temperature fractionation (TF) method. A self-constructed apparatus was used that consisted of an electrical furnace for controlled heating up to 700°C, with a heating rate of 2.2°C·min-1, and an AAS detector with Zeeman background correction. The pattern of Hg release during temperature increase depends highly on the matrix/substrate in which it is contained. Based on spiking gypsum with known Hg compounds we concluded that the largest proportion of Hg in gypsum belongs to Hg-Cl and Hg-Br compounds appearing at 160°C to 200°C, followed by smaller amounts of HgO, HgS and Hg sulfates appearing at 300°C and 450°C. Further development of methodology for identifying Hg species would require identification of the decomposition fragments of Hg and other compounds, complemented by a better understanding of Hg reactivity at higher temperatures.展开更多
基金This work was supported by the Scientific Research Foundation for High Level Talents of Qingdao Agricultural University,China(665-1120015)the National Program for Quality and Safety Risk Assessment of Agricultural Products of China(GJFP2019011)the National Natural Science Foundation of China(42207017).
文摘Winter jujube(Ziziphus jujuba'Dongzao')is greatly appreciated by consumers for its excellent quality,but brand infringement frequently occurs in the market.Here,we first determined a total of 38 elements in 167 winter jujube samples from the main winter jujube producing areas of China by inductively coupled plasma mass spectrometer(ICP-MS).As a result,16 elements(Mg,K,Mn,Cu,Zn,Mo,Ba,Be,As,Se,Cd,Sb,Ce,Er,Tl,and Pb)exhibited significant differences in samples from different producing areas.Supervised linear discriminant analysis(LDA)and orthogonal projection to latent structures discriminant analysis(OPLS-DA)showed better performance in identifying the origin of samples than unsupervised principal component analysis(PCA).LDA and OPLS-DA had a mean identification accuracy of 87.84 and 94.64%in the testing set,respectively.By using the multilayer perceptron(MLP)and C5.0,the prediction accuracy of the models could reach 96.36 and 91.06%,respectively.Based on the above four chemometric methods,Cd,Tl,Mo and Se were selected as the main variables and principal markers for the origin identification of winter jujube.Overall,this study demonstrates that it is practical and precise to identify the origin of winter jujube through multi-element fingerprint analysis with chemometrics,and may also provide reference for establishing the origin traceability system of other fruits.
文摘A multivariate statistical analysis was performed on multi-element soil geochemical data from the Koda Hill-Bulenga gold prospects in the Wa-Lawra gold belt, northwest Ghana. The objectives of the study were to define gold relationships with other trace elements to determine possible pathfinder elements for gold from the soil geochemical data. The study focused on seven elements, namely, Au, Fe, Pb, Mn, Ag, As and Cu. Factor analysis and hierarchical cluster analysis were performed on the analyzed samples. Factor analysis explained 79.093% of the total variance of the data through three factors. This had the gold factor being factor 3, having associations of copper, iron, lead and manganese and accounting for 20.903% of the total variance. From hierarchical clustering, gold was also observed to be clustering with lead, copper, arsenic and silver. There was further indication that, gold concentrations were lower than that of its associations. It can be inferred from the results that, the occurrence of gold and its associated elements can be linked to both primary dispersion from underlying rocks and secondary processes such as lateritization. This data shows that Fe and Mn strongly associated with gold, and alongside Pb, Ag, As and Cu, these elements can be used as pathfinders for gold in the area, with ferruginous zones as targets.
基金supported by the National Natural Science Foundation of China(Grant Nos.52171166,11972372 and U20A20231)supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd。
文摘Energetic structural materials(ESMs)are a new type of structural materials with bearing and damage characteristics.In this work the microstructure,mechanical properties and energy release characteristics of multi-element Ti-Zr-Ta alloys with good casting performance were studied.The microstructure of the Ti_(x)ZrTa alloys gradually change from BCC+HCP to single BCC structure with the increase of Ti.While the Ti_(2)Zr_(y)Ta alloys was still uniform and single BCC structure with the increase of Zr.The evolution of microstructure and composition then greatly affect the mechanical properties and energy-release characteristics of Ti-Zr-Ta alloys.The synergistic effect of dual phase structure increases the fracture strain of Ti_(x)ZrTa(x=0.2,0.5)with the Ti content decreases,while the fracture strain of Ti_(x)ZrTa(x=2.0,3.0,4.0)gradually increase with the Ti content increases caused by the annihilation of the obstacles for dislocation movement.And as Zr content increases,the fracture strain of Ti_(2)Zr_(y)Ta alloys decrease,then the oxidation reaction rate and fragmentation degree gradually increase.The higher oxidation rate and the lager exposed oxidation area jointly leads the higher releasing energy efficiency of Ti_(x)ZrTa alloys with low Ti content and Ti_(2)Zr_(y)Ta alloys with high Zr content.
基金This work was supported by the State Key Lab of Intense Pulsed Radiation Simulation and Effect Basic Research Foundation(No.SKLIPR1504).
文摘To study the effects of the gamma reflection of multi-element materials,gamma ray transport models of single-element materials,such as iron and lead,and multielement materials,such as polyethylene and ordinary concrete,were established in this study.Relationships among the albedo factors of the gamma photons and energies and average energy of the reflected gamma rays by material type,material thickness,incident gamma energy,and incidence angle of gamma rays were obtained by Monte Carlo simulation.The results show that the albedo factors of single-element and multi-element materials increase rapidly with an increase in the material thickness.When the thickness of the material increases to a certain value,the albedo factors do not increase further but rather tend to the saturation value.The saturation values for the albedo factors of the gamma photons,and energies and the reflection thickness are related not only to the type of material but also to the incident gamma energy and incidence angle of the gamma rays.At a given incident gamma energy,which is between 0.2 and 2.5 MeV,the smaller the effective atomic number of the multi-element material is,the higher the saturation values of the albedo factors are.The larger the incidence angle of the gamma ray is,the greater the saturation value of the gamma albedo factor,saturation reflection thickness,and average saturation energy of the reflected gamma photons are.
文摘The paper is to integrate aerodynamic and aero-acoustic optimizatiom design of high lift devices,especially for two-element airfoils with slat.Aerodynamic analysis on flow field utilizes a high-order,high-resolution spatial differential method for large eddy simulation(LES),which can guarantee accuracy and efficiency.The aeroacoustic analysis for noise level is calculated with Ffowcs Williams-Hawkings(FW-H)integration formula.Fidelity of calculation is verified by standard models.Method of streamline-based Euler simulation(MSES)is used to obtain the aerodynamic characters.Based on the confirmation of numerical methods,detailed research has been conducted for the leading edge slat on multi-element airfoils.Various slot parameter influences on noise are analyzed.The results of the slot optimization parameters can be used in multi-element airfoil design.
文摘A factor analysis was applied to soil geochemical data to define anomalies related to buried Pb-Zn mineralization.A favorable main factor with a strong association of the elements Zn,Cu and Pb,related to mineralization,was selected for interpretation.The median+2 MAD(median absolute deviation)method of exploratory data analysis(EDA)and C-A(concentration-area)fractal modeling were then applied to the Mahalanobis distance,as defined by Zn,Cu and Pb from the factor analysis to set the thresholds for defining multi-element anomalies.As a result,the median+2 MAD method more successfully identified the Pb-Zn mineralization than the C-A fractal model.The soil anomaly identified by the median+2 MAD method on the Mahalanobis distances defined by three principal elements(Zn,Cu and Pb)rather than thirteen elements(Co,Zn,Cu,V,Mo,Ni,Cr,Mn,Pb,Ba,Sr,Zr and Ti)was the more favorable reflection of the ore body.The identified soil geochemical anomalies were compared with the in situ economic Pb-Zn ore bodies for validation.The results showed that the median+2 MAD approach is capable of mapping both strong and weak geochemical anomalies related to buried Pb-Zn mineralization,which is therefore useful at the reconnaissance drilling stage.
文摘Multi-element analysis in historical sites is a major issue in archaeological studies;however,this approach is almost unknown among Iranian scholars.Geochemical multi-element analysis of soil is very important to evaluate anthropogenic activities.The aim of this study consists of assessing the potential usefulness of multi-elemental soil analysis,obtained by Analytical Jena atomic absorption spectrophotometer(AAS) and ICP-MS,to recognize ancient anthropogenic features on the territory of Tappe Rivi(North Khorasan,Iran).For that purpose,a total of 80 ancient soil samples were sampled from each soil horizon and cultural layer.The research involved Fe,Al,Cd,Cu,Ni,Co,Cr,Pb,and P which trace element samples were extracted according to the International Standard ISO 11466 and phosphorus samples by Olsen method.Besides,the contamination of the soils was assessed based on enrichment factors(EFs) by using Fe as a reference element.This geochemical/archaeological approach highlights that the content of most elements in the Parthian and Sassanid ages were significantly higher than the contents of the elements in other zones,which shows that by the development of the eras,the content of the elements has also increased.Also,the accumulation of metals in the Rivi site was significantly higher than in the control area.Among the sampled zones,enrichment factor(EF) indicated that the enrichment of Cu and phosphate at the Parthian and Sassanid had the highest content.This result is important because it shows that the amount of metals and human activities are directly related to each other during different ages.
基金Supported by the National Natural Science Foundation of China(11172134)the Funding of Jiangsu Innovation Program for Graduate Education(CXZZ110192)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A hybrid Cartesian grid/gridless method is developed for calculating viscous flows over multi-element airfoils.The method adopts an unstructured Cartesian grid to cover most areas of the computational domain and leaves only small region adjacent to the aerodynamic bodies to be filled with the cloud of points used in the gridless methods,which results in a better combination of the computational efficiency of the Cartesian grid and the flexibility of the gridless method in handling complex geometries.The clouds of points in the local gridless region are implemented in an anisotropic way according to the features of the thin boundary layer of the viscous flows over the airfoils,and the clouds of points at the vicinity of the interface between the grid and the gridless regions are also controlled by using an adaptive refinement technique during the generation of the unstructured Cartesian grid.An implementation of the resulting hybrid method is presented for solving two-dimensional compressible Navier-Stokes(NS)equations.The simulations of the viscous flows over a RAE2822airfoil or a two-element airfoil are successfully carried out,and the obtained results agree well with the available experimental data.
基金This work was supported by the Hainan Provincial Natural Science Foundation of China[2018CXTD333,617048]National Natural Science Foundation of China[61762033,61702539]+1 种基金Hainan University Doctor Start Fund Project[kyqd1328]Hainan University Youth Fund Project[qnjj1444].
文摘Traditional distributed denial of service(DDoS)detection methods need a lot of computing resource,and many of them which are based on single element have high missing rate and false alarm rate.In order to solve the problems,this paper proposes a DDoS attack information fusion method based on CNN for multi-element data.Firstly,according to the distribution,concentration and high traffic abruptness of DDoS attacks,this paper defines six features which are respectively obtained from the elements of source IP address,destination IP address,source port,destination port,packet size and the number of IP packets.Then,we propose feature weight calculation algorithm based on principal component analysis to measure the importance of different features in different network environment.The algorithm of weighted multi-element feature fusion proposed in this paper is used to fuse different features,and obtain multi-element fusion feature(MEFF)value.Finally,the DDoS attack information fusion classification model is established by using convolutional neural network and support vector machine respectively based on the MEFF time series.Experimental results show that the information fusion method proposed can effectively fuse multi-element data,reduce the missing rate and total error rate,memory resource consumption,running time,and improve the detection rate.
基金The National Natural Science Foundation of China (No.50478090)
文摘A set of serf-developed apparatus for foundation physical model were utilized to conduct model tests of the multi-element composite foundation with a steel pipe pile and several gravel piles. Some load-bearing characteristics of the multi-element Composite foundation, including the curves of foundation settlement, stresses of piles, pile-soil stress ratio, and load-sharing ratio of piles and soil, were obtained to study its working performances in silty sand soil. The experimental results revealed that the multi-element composite foundation with steel pipe pile and gravel pile contributed more than the gravel pile composite foundation in improving the bearing capacity of the silty fine sand.
基金supported by the Universiti Kebangsaan Malaysia research grant(Grant No.GGP-2020-012)。
文摘This investigation aimed to establish the geographical traceability of Malaysian rice by assessing the elemental composition in paddy soil.Multi-element determination in combination with a chemometric approach was applied to evaluate the elemental concentrations of paddy soil from granaries cultivated with the same rice variety and to assess the relationship between elements in the soil and rice(SAR) system.A total of 29 elements(aluminum,arsenic,barium,bromine,calcium,chlorine,cobalt,chromium,cesium,europium,iron,gallium,hafnium,potassium,lanthanum,lutetium,magnesium,manganese,sodium,rubidium,antimony,scandium,samarium,thorium,titanium,uranium,vanadium,ytterbium and zinc) were successfully determined in paddy soil from Kedah,Selangor and Langkawi by neutron activation analysis.A significant difference(P < 0.05) between 18 elements in the soil samples was obtained.The chemometric approaches of principal component and linear discriminant analyses demonstrated clear discrimination and highly corrected classification(100%) of the soil samples.A high classification(98.1%) was also achieved by assessing 10 elements(aluminum,arsenic,bromine,chlorine,potassium,magnesium,manganese,sodium,rubidium and zinc),which similarly applied to rice geographical origin determination.Similar elements in SAR were also observed for differences in the pattern of correlation and bioaccumulation factor between the granaries.Furthermore,the generalized Procrustes analysis showed a 98% consensus between SAR and clear differences between the studied regions.The canonical correlation analysis demonstrated a significant correlation between the chemical profile of SAR(r~2 = 0.88,P < 0.001).Therefore,the current work model provides a reliable assessment to establish rice provenance.
基金supported by Project of the Xi’an Science and Technology Innovation talent service enterprise project(No.2020KJRC0041)National Natural Science Foundation of China(No.62073256)Key Programs of Shaanxi Science and Technology Department(No.2020GY-125)。
文摘Multi-element array photoelectric detector is the core devices to form a photoelectric detection target with a large field of view.This photoelectric detection target brings about the problem of uneven detection sensitivity distribution in the detection screen.To improve the uneven detection sensitivity of this photoelectric detection target,this paper analyzes the distribution law of the uneven detection sensitivity of the photoelectric detection target using the multi-element array photoelectric detector,dissects the main factors affecting the detection sensitivity according to the photoelectric detection principle,establishes the calculation model of detection sensitivity of the photoelectric detection target in the different detection areas and proposes a method to improve the detection sensitivity by compensating the gain of each unit photoelectric detector.The analysis of simulation and experimental results show that the proposed method of photoelectric detection target can effectively improve the output signal amplitude of the projectile under the certain detection distance,in particular,the output signal amplitude of the projectile is significantly increased when the projectile passes through the detection blind area.The experimental results are consistent with the simulation results,which verify the effectiveness of the proposed improvement method.
文摘The broad implication of the paper is to elucidate the significance of the dynamic heaving motion in the aerodynamic performance of multi-element wings,currently considered as a promising aspect for the improvement of the aerodynamic correlation between CFD,wind tunnel and track testing in race car applications.The relationship between the varying aerodynamic forces,the vortex shedding,and the unsteady pressure field of a heaving double-element wing is investigated for a range of mean ride heights,frequencies,and amplitudes,using a two-dimensional(2D)unsteady Reynolds-averaged Navier-Stokes(URANS)approach and an overset mesh method for modelling the moving wing.The analysis of the results shows that at high frequencies,i.e.,k≥5.94 and amplitudes a/c≥0.05 the interaction of the shear vorticity between the two elements results in the generation of cohering leading and trailing edge vortices on the flap,associated to the rapid variation of thrust and downforce enhancement.Both the occurrence and intensity of these vortices are dependent upon the frequency,amplitude,and mean ride height of the heaving wing.The addition of the flap significantly alters the frequency of the shed vortices in the wake and maintains the generation of downforce for longer time in ground proximity.The comparison with the static wing provides evidence that the dynamic motion of a race car wing can be beneficial in terms of performance,or detrimental in terms of aerodynamic correlation.
文摘A direct and simple method for the clinic muti-element determination of human blood sample by Zeeman graphite furnace atomic absorption spectropho-tometry is reported. No pretreatment of the sample is necessary other than simple dilution of the sample with aqueous solution of Triton X-100. The detection limits of the elements investigated fall in the range of 0.1- 4.4 μg/L with a relative standard deviation ranging from 1.6 for zinc to 3.73% for lead. Micro liters of samples are sufficient for the determination of each element.
文摘A model is developed for predicting the correlation between processing parameters and the technical target of double glow by applying artificial neural network (ANN). The input parameters of the neural network (NN) are source voltage, workplace voltage, working pressure and distance between source electrode and workpiece. The output of the NN model is three important technical targets, namely the gross element content, the thickness of surface alloying layer and the absorption rate (the ratio of the mass loss of source materials to the increasing mass of workpiece) in the processing of double glow plasma surface alloying. The processing parameters and technical target are then used as a training set for an artificial neural network. The model is based on multiplayer feedforward neural network. A very good performance of the neural network is achieved and the calculated results are in good agreement with the experimental ones.
文摘A new siplitter plate presure probe was developed for flow field measurements on an airfoil with slotted flap in a low speed wind tunnel with 7 by 10 ft test section. Wind tunnel tests were conducted at a Reynolds number of 2.2 million and Mach number of 0.13. The splitter plate was made of aluminum and had pressure taps on its one side. The probe can make many measurements in the plane of the plate simultaneously by using these pressure tabs. It was supported by a traversing strut in the wind tunnel and surveyed the flow field on the airfoil upper surface. Measured pressures were presented by isobars of coefficients. These isobars were connected with the pressure coefficients distributed over the airfoil. Results of splitter plate pressure probe compare well with other single-point measuring probes. However, results show that no matter how small the probe, its presence in the flow causes a disturbance, especially in the highly time-dependent separated flow regions.
文摘Objective: based on the analysis to the elements affecting the results of China's national team in the 2010 mountain outdoor sports adventure challenge race in Abu Dhabi, some theoretical and practical basis on which suggestions are provided on further promoting China's mountain outdoor sports results and the competitive level are given.Subjects: athletic performance of the top six teams and China's national team in 2010 mountain outdoor sports and athletic performance;Methods: using expert interviews, reference and data, mathematical statistics, analyze the athletic performance of the top six teams and China's national team in 2010 mountain outdoor sports and athletic performance on foot and bicycle projects on class projects with the world's top mountain outdoor big gap between sports teams;Result: there are big gaps between China's mountain outdoor sports teams and foreign teams on projects like footing and bicycling;Conclusion: Although in recent years, our mountain outdoor sports performance has been greatly improved, but the large gap do exist on foot and bicycle projects. so these projects need strengthening .
基金supported by the National Key Project of China(No.GJXM92579)National Natural Science Foundation of China(Nos.92052203,11872230 and 91852108)。
文摘Almost half of all flight accidents caused by inflight icing occur at the approach and landing phases when high-lift devices are deployed.The present study focuses on the optimization of an ice-tolerant multi-element airfoil.Dual-objective optimization is carried out with critical hornshaped ice accumulated during the holding phase.The optimization results show that the present optimization method significantly enhances the iced-state and clean-state performance.The optimal multi-element airfoil has a larger deflection angle and wider gap at the slat and the flap compared with the baseline configuration.The sensitivity of each design parameter is analyzed,which verifies the robustness of the design.The design is further assessed when ice is accreted during the approach and landing phases,which also shows performance improvement.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102024 and 11721202)the China Postdoctoral Science Foundation(Grant Nos.2021M700010 and 2022T150036)。
文摘The flow around the slat cove of a two-dimensional 30P30N multi-element airfoil is investigated with time-resolved particle image velocimetry(TR-PIV)at low Reynolds number(Rec=2.41×10^(4)and 4.61×10^(4)).The effects of angle of attack(α=8°,12°,and 16°)on the mean flow characteristics and vortex dynamics are discussed.The size of the recirculation within the slat cove and the intensity of the shed vortices originating from the slat cusp shear layer are found to generally decrease as the angle of attack increases.The joint time-frequency analyses show that disturbances of different frequencies exist in the slat cusp shear layer and they trigger the different vortex shedding patterns of the slat cusp shear layer.The self-sustained oscillation within the slat cove,normally observed at high Reynolds number(Re_(c)~10^(6)),is proved to be responsible for the disturbances of different frequencies and the related vortex dynamics in the current study.
基金supported by the ARRS program P1-0143,a project J1-4288 and the ARRS young researcher program as well as the program“Young researchers from Industry 2010”partly financed by the European Union,European Social Fundfinancial support from the state budget by the Slovenian Research Agency.
文摘Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Sostanj, Slovenia, can efficiently retain mercury (Hg), of which most is contained in finer gypsum fractions, with concentrations above 10 kg-1. The aim of this work was to identify and study the temperature stability of Hg species in gypsum by a temperature fractionation (TF) method. A self-constructed apparatus was used that consisted of an electrical furnace for controlled heating up to 700°C, with a heating rate of 2.2°C·min-1, and an AAS detector with Zeeman background correction. The pattern of Hg release during temperature increase depends highly on the matrix/substrate in which it is contained. Based on spiking gypsum with known Hg compounds we concluded that the largest proportion of Hg in gypsum belongs to Hg-Cl and Hg-Br compounds appearing at 160°C to 200°C, followed by smaller amounts of HgO, HgS and Hg sulfates appearing at 300°C and 450°C. Further development of methodology for identifying Hg species would require identification of the decomposition fragments of Hg and other compounds, complemented by a better understanding of Hg reactivity at higher temperatures.