<div style="text-align:justify;"> Rainfall infiltration is a porous medium flow problem with variable saturation. Based on the theoretical analysis of the flow field, electrical conductivity of rocks, ...<div style="text-align:justify;"> Rainfall infiltration is a porous medium flow problem with variable saturation. Based on the theoretical analysis of the flow field, electrical conductivity of rocks, the electrical field, the paper simulates the coupling relationship between the water saturation in soil and the apparent resistivity distribution. It combines the Richards equation, the Archie formula and the Laplace equation. The experiment simulates the potential field data by the Wenner setting in electrical exploration on a two-layer geologic model with continuous rainfall during 5 days, which shows that the effective saturation in soil is increasing with the rainfall time, while the apparent resistivity is decreasing. This can provide a theoretical basis for the analyzing the rainfall infiltration and porosity of the soil by using high-density electrical method in the future. </div>展开更多
This study prepares a group of single crystalline β-Zn_4Sb_3 with Ge and Sn codoped by the Sn-flux method according to the nominal stoichiometric ratios of Zn_(4.4)Sb_3 Ge_xSn_3(x = 0–0.15). The prepared samples...This study prepares a group of single crystalline β-Zn_4Sb_3 with Ge and Sn codoped by the Sn-flux method according to the nominal stoichiometric ratios of Zn_(4.4)Sb_3 Ge_xSn_3(x = 0–0.15). The prepared samples possess a metallic luster surface with perfect appearance and large crystal sizes. The microscopic cracks or defects are invisible in the samples from the back-scattered electron image. Except for the heavily Ge-doped sample of x = 0.15, all the samples are single phase with space group R3c. The thermal analysis results show that the samples doped with Ge exhibit an excellent thermal stability.Compared with the polycrystalline Ge-substituted β-Zn_4Sb_3, the present single crystals have higher carrier mobility, and hence the electrical conductivity is improved, which reaches 7.48×10~4S·m^(-1) at room temperature for the x = 0.1 sample.The change of Ge and Sn contents does not improve the Seebeck coefficient significantly. Benefiting from the increased electrical conductivity, the sample with x = 0.075 gets the highest power factor of 1.45×10^(-3)W·m^(-1)·K^(-2) at 543 K.展开更多
The ELECTRE(ELimination Et Choix Traduisant la REalite)method has gained widespread recognition as one of the most effective multi-criteria decision-making(MCDM)methods.Its versatility allows it to be applied in a wid...The ELECTRE(ELimination Et Choix Traduisant la REalite)method has gained widespread recognition as one of the most effective multi-criteria decision-making(MCDM)methods.Its versatility allows it to be applied in a wide range of areas such as engineering,economics,business,environmental management and many others.This paper aims to provide an overview of the ELECTRE method,including its fundamental concepts,applications,advantages,and limitations.At its core,the ELECTRE method is an outranking family of MCDM techniques,which allows for the direct comparison of alternatives based on a set of criteria.The method takes into account the preferences and importance of decision-makers and generates a ranking of the alternatives based on their relative strengths and weaknesses.The ELECTRE method is a powerful tool for decision-making,and its applicability to a wide range of fields demonstrates its versatility and adaptability.By understanding its concepts,applications,merits,and demerits,decision-makers can use the ELECTRE method to make informed and effective decisions in a variety of contexts.展开更多
In Brazil and various regions globally, the initiation of landslides is frequently associated with rainfall;yet the spatial arrangement of geological structures and stratification considerably influences landslide occ...In Brazil and various regions globally, the initiation of landslides is frequently associated with rainfall;yet the spatial arrangement of geological structures and stratification considerably influences landslide occurrences. The multifaceted nature of these influences makes the surveillance of mass movements a highly intricate task, requiring an understanding of numerous interdependent variables. Recent years have seen an emergence in scholarly research aimed at integrating geophysical and geotechnical methodologies. The conjoint examination of geophysical and geotechnical data offers an enhanced perspective into subsurface structures. Within this work, a methodology is proposed for the synchronous analysis of electrical resistivity geophysical data and geotechnical data, specifically those extracted from the Light Dynamic Penetrometer (DPL) and Standard Penetration Test (SPT). This study involved a linear fitting process to correlate resistivity with N10/SPT N-values from DPL/SPT soundings, culminating in a 2D profile of N10/SPT N-values predicated on electrical profiles. The findings of this research furnish invaluable insights into slope stability by allowing for a two-dimensional representation of penetration resistance properties. Through the synthesis of geophysical and geotechnical data, this project aims to augment the comprehension of subsurface conditions, with potential implications for refining landslide risk evaluations. This endeavor offers insight into the formulation of more effective and precise slope management protocols and disaster prevention strategies.展开更多
Creep-fatigue test was carried out using smooth round bar specimens of Type 304 stainless steel. Cavities and small cracks on the cross-section of the specimen were carefully observed by a scanning laser microscope. ...Creep-fatigue test was carried out using smooth round bar specimens of Type 304 stainless steel. Cavities and small cracks on the cross-section of the specimen were carefully observed by a scanning laser microscope. Moreover, direct current electrical potential method (DC-EPM) was applied in order to evaluate non-destructively the distribution of internal cracks. The distribution evaluated by DC-EPM agrees well with the actual one. (Edited author abstract) 9 Refs.展开更多
Garbage disposal has gradually become a key issue faced by environmental governance. What must be controlled in garbage disposal is the calculation of garbage volume. In this paper, according to the different landfill...Garbage disposal has gradually become a key issue faced by environmental governance. What must be controlled in garbage disposal is the calculation of garbage volume. In this paper, according to the different landfill conditions of a landfill in Anhui, including: covering soil, overlying HDPE membrane, overlying concrete, etc., combined with the physical differences between the rock mass and the garbage at the bottom of the landfill. The landfill covered with HDPE membrane adopts the transient electromagnetic method, the landfill covered with soil layer adopts the high-density electrical method, and the landfill covered with concrete adopts the combination of transient electromagnetic method and ground penetrating radar. At the same time, Combines the borehole data to determine that the resistivity value of the interface between the garbage and the soil was 29 Ω⋅m. Finally, the sections of multiple survey lines can accomplish three-dimensional stereoscopic that calculate the distribution and actual volume of the garbage. This method is used to determine the final investment cost.展开更多
This report evaluates the use of electrical method and borehole data to investigate the subsurface to delineate the groundwater potential in Enugu metropolis and the environs, south-eastern Nigeria other than rely onl...This report evaluates the use of electrical method and borehole data to investigate the subsurface to delineate the groundwater potential in Enugu metropolis and the environs, south-eastern Nigeria other than rely only on resistivity method w</span><span style="font-family:Verdana;">hich could lead to interpretation error. Integrating these 2 data sets is key in this study. The study area is located in the Anambra Basin and is underlain by Nkporo/Enugu Shale which is overlain by the Mamu Formation. It is bounded by Latitudes 6</span><span style="font-family:Verdana;"><span style="white-space:nowrap;">°</span>2 0'00</span></span><span style="font-family:Verdana;">"</span><span style="font-family:Verdana;">N to 6<span style="white-space:nowrap;">°</span>30'00</span><span style="font-family:Verdana;">"</span><span style="font-family:Verdana;">N and Longitudes 7<span style="white-space:nowrap;">°</span>25'00</span><span style="font-family:Verdana;">"</span><span style="font-family:Verdana;">E to 7<span style="white-space:nowrap;">°</span>35'00</span><span style="font-family:Verdana;">"</span><span style="font-family:""><span style="font-family:Verdana;">E and covers surface area of about 342 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">. Thirty</span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">one vertical electrical soundings (VES) were carried out across the area using the Schlumberger electrode array with current electrode separation from 2 to 500 m to identify the depths and resistivity values of the identified geo-electric layers. Through data analysis using WinResist software, the apparent resistivity, thicknesses and depths and the thicknesses of the aquifers were generated. The resistivity</span><span style="font-family:""> </span><span style="font-family:Verdana;">and depths were modelled to generate resistivity map and depth map. The resistivity of the aquiferous zone within the study area varie</span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;"> from 20.55</span><span style="font-family:""> - </span><span style="font-family:Verdana;">427.8 ohm-m at depths of between 10.7</span> - <span style="font-family:Verdana;">40.05 m. Depth to the water table appears to be shallow at the south western part of the map. The interpreted geo-electric layers show a sequence of lateritic top soil, shale, sand and shale. The frequency distribution of the VES curves generated shows the presence of 3 to 5 layers with HK type as the highest. Also, a 2D model was generated using the correlation of VES to VES data and borehole data to VES data to show the underlying stratigraphy beneath the study area as well as the direction of ground water flow. Result of the VES curve analysis reveal</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> that the sub-surface is underlain by three lithological layers namely: lateritic top soil, shale, sand and shales with NW direction of groundwater flow from the 2D model. Groundwater prospective zones can be seen along NW, SW and central parts of the study area which have low resistivity values.展开更多
A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon sour...A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.展开更多
Carbon nanotubes(CNTs) were synthesized by the electric heating catalytic chemical deposition method(CCVD) using acetylene(C2H2) as the carbon source and nitrogen(N2) as carrier gas,and nickel catalyst was loa...Carbon nanotubes(CNTs) were synthesized by the electric heating catalytic chemical deposition method(CCVD) using acetylene(C2H2) as the carbon source and nitrogen(N2) as carrier gas,and nickel catalyst was loaded by electroplating.The electric heating method,as a new method,electrifies the carbon fiber directly by using its conductivity.The morphology and structure of CNTs were characterized by SEM and TEM,and the surface properties of carbon fibers before and after the growth of CNT were characterized by Raman spectroscopy.The experimental results show that the electric heating method is a new method to produce CNT,and can grow a large number of CNTs in a short time,the crystallization degree and surface average crystallite size of carbon fiber increased after the growth of CNT on it.In addition,electroplating loading catalyst can also be used as an ideal loading way,which can control the number,shape,and distribution of nickel particles by controlling the plating time.展开更多
According to computer numerical simulation for measuring atmosphere carbon potential by electric resistance method (hot-wire method) and the experimental data, the paper point out that the measuring result dose not d...According to computer numerical simulation for measuring atmosphere carbon potential by electric resistance method (hot-wire method) and the experimental data, the paper point out that the measuring result dose not directly reflect the atmosphere carbon potential (Cg) but the average carbon content, and as a result, the change of electric resistance obviously lag to that of the atmosphere carbon potential. In order to correctly control the carbon potential by electric resistance method, the authors bring forward a function which is a better expression for the relationship between the average carbon content of the wire and the atmosphere carbon potential and ensures good carbon potential control.展开更多
The traditional measurement method was inaccurate to evaluate the motor controller efficiency,which the measurement efficiency value could be more than 100%in practical testing experiments.To deal with this issue,an i...The traditional measurement method was inaccurate to evaluate the motor controller efficiency,which the measurement efficiency value could be more than 100%in practical testing experiments.To deal with this issue,an improved electrical measurement method for the motor controller efficiency is proposed in this paper,which is established by analyzing the power loss distribution and phase currents of the motor controller.It is demonstrated that the SiC MOSFET chips are the main power loss devices in the motor controller,accounting for more than 93.1%of the total power loss.The accuracy of the proposed method is compared with the traditional method in simulation.It shows that the test error of the efficiency obtained by the traditional method fluctuates on a large scale,which varied from 0.094%to 1.911%.Compared with the traditional method,the test error of the proposed method appears to be less than 0.083%,which provides significant guidance for the motor controller efficiency test and design.展开更多
In order to study evolution laws of tensile fractures in a coal mining area, based on the classification of the fractures formed by mining, a physical simulation test was carried out to simulate the dynamic evolut...In order to study evolution laws of tensile fractures in a coal mining area, based on the classification of the fractures formed by mining, a physical simulation test was carried out to simulate the dynamic evolution process of tensile fractures in coal mining areas. The results showed that after the coal in the mining area was mined, the mining area underwent obvious movement and deformation and forms tensile fractures. As the min-ing working face was advanced, the tensile fractures underwent the dynamic process of generation, development and closure. The changing curves of density of tensile fractures with the increase of mining length of the working face liked a ladder (it increased slowly and then rapidly) and then had two peaks (the second peak was higher than the first peak).展开更多
In the light of its negative impacts on the environment and human health, conventional agriculture is currently facing new challenges;for example, reducing pesticide reliance, improving biodiversity, adapting to clima...In the light of its negative impacts on the environment and human health, conventional agriculture is currently facing new challenges;for example, reducing pesticide reliance, improving biodiversity, adapting to climate change and reconciling winegrowers with consumers, which require changes to be made to vineyard management. A shift towards more sustainable agriculture via the development of agroecological systems may be key to meeting these environmental, economic and social challenges. This study aimed to evaluate the performance of existing viticultural systems, as well as that of three new scenarios that we built to change conventional vine production systems and their related practices. The end aim is to adopt the principles of agroecology, and more virtuously, to ensure that vine production remains in line with societal expectations. First, thirty-eight different viticultural systems were chosen. Three realistic scenarios for changing these production systems were then built by working with stakeholders and incorporating the best practices that had been identified in the vineyard. Conventional practices were optimised in the first scenario and an agroecological approach was adopted for the other two scenarios: an Agroecological scenario (using synthetic chemicals) and an Agroecological-Bio scenario (organic system). All three scenarios were based on a combination of good practices which contribute to enhancing vineyard biodiversity, and which thus restore biological regulation and in turn reduce pesticides. The viticultural systems performances have been evaluated with a methodology involving multicriteria decision aid using ELECTRE Tri-C and ELECTRE III methods. Seven evaluation criteria were selected which covered socio-economic performance (economic profitability, workload and system complexity) and environmental performance (pesticide pressure, pesticide ecotoxicity, agroecological practices and pesticide drift). The best performances were achieved by the two agroecological scenarios, and this methodology can be adaptable to different production systems everywhere in different viticultural regions.展开更多
This paper is devoted to the analysis of the nonlinear Stability of a clamped rodcarrying electric current in the magnetic field which is produced by the current frowingin a pair of inifinitely long parallel rigid wi...This paper is devoted to the analysis of the nonlinear Stability of a clamped rodcarrying electric current in the magnetic field which is produced by the current frowingin a pair of inifinitely long parallel rigid wires. The natural State of the rod is in theplane of the wires and is equidistant from them.Firstly under the assumption of apatial deformation, the governing equations of the problem are derived, and the linearizedproblem and critical currents are discussed. Secondly, it ls proved that the buckledstates of the rod are always in planes. Finally. the global responses of the bifurcationproblem of the rod are compuled numerically and the distributions of the deflections.axial forces and bending monents are obtained. The results show that the buckledslates of the rod may be either supercritical or Subcritical. depending on the distancebetween the rod and the wires. Furthermore, it is found that -there exists a limit pointon the branch solution of the supercritical buckled State. This is distinctively differentfrom the buckled slate of the elastic compressive rods.展开更多
Composite structures are sensitive to impact damage in practical engineering.Electric resistance change method(ERCM)is an ideal technique for damage monitoring of composite structures.Due to the anisotropy of fiber-re...Composite structures are sensitive to impact damage in practical engineering.Electric resistance change method(ERCM)is an ideal technique for damage monitoring of composite structures.Due to the anisotropy of fiber-resin matrix composites,impact location monitoring is difficult,and research on impact location of fiber composite laminates(FRPs)is limited.A preparation method of MXene/CNT/CuNps thin film sensor is proposed.According to the modeling simulation and theoretical calculation,the resistance change characteristics of the thin film sensor are obtained,the relationship between the impact distance and the resistance change is established,and the sensor array is designed.A three-point localization algorithm and a weight function compensation localization algorithm are proposed,which can improve the imaging accuracy of the impact position.The impact point location was observed and analyzed using ultrasonic C-scan technology.The results show that the weight function compensation positioning algorithm can accurately locate the impact of the composite structure,and the error in the X direction is 7.1%,the error in the Y direction is 0.03%,which verifies the effectiveness of the method.展开更多
Background Despite outstanding antiplatelet properties of aspirin and clopidogrel, some patients taking these drugs continue to suffer complications. Antiplatelet resistance appears to be a new prognostic factor in ac...Background Despite outstanding antiplatelet properties of aspirin and clopidogrel, some patients taking these drugs continue to suffer complications. Antiplatelet resistance appears to be a new prognostic factor in acute coronary syndrome patients for clinical events associated with stent thrombosis (ST). However, there is no optimal method to identify it and assess its correlation to clinical outcomes. This study sought to evaluate the predictive value of antiplatelet resistance assessed by whole blood impedance aggregometry for the risk of early ST in patients with acute coronary syndrome who underwent coronary stenting. Methods Platelet responses to aspirin and clopidogrel in 86 patients with acute coronary syndrome were measured by whole blood impedance aggregometry. Spontaneous platelet aggregation was defined as antiplatelet resistance identified by the increased electrical impedance. The clinical endpoint was early stent thrombosis during 30-day follow-up after coronary stenting. Results The prevalence of aspirin resistance, clopidogrel resistance and dual resistance of combined clopidogrel and aspirin resistance were 19.8%, 12.8% and 5.8% respectively. Diabetes, female and higher platelet counts were more frequently detected in clopidogrel-resistant and dual-resistant patients. During 30-day follow-up, the patients with clopidogrel resistance and dual resistance had higher incidence of early stent thrombosis (18.2% vs. 1.3%, 40.0% vs. 1.2%, P 〈0.05). Binary Logistic Regression analysis indicated that dual resistance remained an independent predicator for early stent thrombosis (odds ratio 34.064, 95% CI 1.919-604.656, P=-0.016). Conclusions Antiplatelet resistance assessed by whole blood impedance aggregometry is paralleled to clinical events, and dual antiplatelet resistance is an independent predicator for early stent thrombosis in patients with acute coronary syndrome. As a physiological assessment of platelet reactivity, whole blood impedance aggregometry is a convenient and accurate option for measurin.q antiplatelet resistance and hence predicting early stent thrombosis.展开更多
Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and use...Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and used to calculate electric field at the steady state through the finite element analysis. Based on the simulation of the electric field, the operational and structural parameters, such as the current intensity, anode thickness, cathode thickness, and anode-cathode distance (ACD), were investigated to obtain the minimum cell voltage. The optimization is to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The results indicate that the effect of the current intensity on the voltage could be ignored and the effect of the ACD is obvious. Moreover, there is a linear decrease between the voltage and the thicknesses of the anode and cathode; and the anodecathode working height also has a significant effect on the voltage.展开更多
Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and num...Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and numerical modeling are performed in this paper to investigate the behavior of an actively cooled thermal protection system. The analytic estimation is based on the electric analogy method and finite element analysis(FEA) is applied to the numerical simulation. Temperature and stress distributions are obtained for the actively cooled channel walls with three kinds of nickel alloys with or with no thermal barrier coating(TBC). The temperature of the channel wall with coating has no obvious difference from the one with no coating, but the stress with coating on the channel wall is much smaller than that with no coating. Inconel X-750 has the best characteristics among the three Ni-based materials due to its higher thermal conductivity, lower elasticity module and greater allowable stress. Analytic estimation and numerical modeling results are compared with each other and a reasonable agreement is obtained.展开更多
The thermal characteristics of high-power AlGaAs/GaAs laser diodes(LDs) at high current(2-10 A)are studied with electrical transient method.The temperature rise increases linearly with the current.The thermal resi...The thermal characteristics of high-power AlGaAs/GaAs laser diodes(LDs) at high current(2-10 A)are studied with electrical transient method.The temperature rise increases linearly with the current.The thermal resistance of chip is the largest proportion of total thermal resistance.By increasing the width of the chip from 500 to 800 fim,the temperature rise and thermal resistance decrease by 8.5%and 8.8%,respectively.展开更多
文摘<div style="text-align:justify;"> Rainfall infiltration is a porous medium flow problem with variable saturation. Based on the theoretical analysis of the flow field, electrical conductivity of rocks, the electrical field, the paper simulates the coupling relationship between the water saturation in soil and the apparent resistivity distribution. It combines the Richards equation, the Archie formula and the Laplace equation. The experiment simulates the potential field data by the Wenner setting in electrical exploration on a two-layer geologic model with continuous rainfall during 5 days, which shows that the effective saturation in soil is increasing with the rainfall time, while the apparent resistivity is decreasing. This can provide a theoretical basis for the analyzing the rainfall infiltration and porosity of the soil by using high-density electrical method in the future. </div>
基金Project supported by the National Natural Science Foundation of China(Grant No.51262032)
文摘This study prepares a group of single crystalline β-Zn_4Sb_3 with Ge and Sn codoped by the Sn-flux method according to the nominal stoichiometric ratios of Zn_(4.4)Sb_3 Ge_xSn_3(x = 0–0.15). The prepared samples possess a metallic luster surface with perfect appearance and large crystal sizes. The microscopic cracks or defects are invisible in the samples from the back-scattered electron image. Except for the heavily Ge-doped sample of x = 0.15, all the samples are single phase with space group R3c. The thermal analysis results show that the samples doped with Ge exhibit an excellent thermal stability.Compared with the polycrystalline Ge-substituted β-Zn_4Sb_3, the present single crystals have higher carrier mobility, and hence the electrical conductivity is improved, which reaches 7.48×10~4S·m^(-1) at room temperature for the x = 0.1 sample.The change of Ge and Sn contents does not improve the Seebeck coefficient significantly. Benefiting from the increased electrical conductivity, the sample with x = 0.075 gets the highest power factor of 1.45×10^(-3)W·m^(-1)·K^(-2) at 543 K.
文摘The ELECTRE(ELimination Et Choix Traduisant la REalite)method has gained widespread recognition as one of the most effective multi-criteria decision-making(MCDM)methods.Its versatility allows it to be applied in a wide range of areas such as engineering,economics,business,environmental management and many others.This paper aims to provide an overview of the ELECTRE method,including its fundamental concepts,applications,advantages,and limitations.At its core,the ELECTRE method is an outranking family of MCDM techniques,which allows for the direct comparison of alternatives based on a set of criteria.The method takes into account the preferences and importance of decision-makers and generates a ranking of the alternatives based on their relative strengths and weaknesses.The ELECTRE method is a powerful tool for decision-making,and its applicability to a wide range of fields demonstrates its versatility and adaptability.By understanding its concepts,applications,merits,and demerits,decision-makers can use the ELECTRE method to make informed and effective decisions in a variety of contexts.
文摘In Brazil and various regions globally, the initiation of landslides is frequently associated with rainfall;yet the spatial arrangement of geological structures and stratification considerably influences landslide occurrences. The multifaceted nature of these influences makes the surveillance of mass movements a highly intricate task, requiring an understanding of numerous interdependent variables. Recent years have seen an emergence in scholarly research aimed at integrating geophysical and geotechnical methodologies. The conjoint examination of geophysical and geotechnical data offers an enhanced perspective into subsurface structures. Within this work, a methodology is proposed for the synchronous analysis of electrical resistivity geophysical data and geotechnical data, specifically those extracted from the Light Dynamic Penetrometer (DPL) and Standard Penetration Test (SPT). This study involved a linear fitting process to correlate resistivity with N10/SPT N-values from DPL/SPT soundings, culminating in a 2D profile of N10/SPT N-values predicated on electrical profiles. The findings of this research furnish invaluable insights into slope stability by allowing for a two-dimensional representation of penetration resistance properties. Through the synthesis of geophysical and geotechnical data, this project aims to augment the comprehension of subsurface conditions, with potential implications for refining landslide risk evaluations. This endeavor offers insight into the formulation of more effective and precise slope management protocols and disaster prevention strategies.
文摘Creep-fatigue test was carried out using smooth round bar specimens of Type 304 stainless steel. Cavities and small cracks on the cross-section of the specimen were carefully observed by a scanning laser microscope. Moreover, direct current electrical potential method (DC-EPM) was applied in order to evaluate non-destructively the distribution of internal cracks. The distribution evaluated by DC-EPM agrees well with the actual one. (Edited author abstract) 9 Refs.
文摘Garbage disposal has gradually become a key issue faced by environmental governance. What must be controlled in garbage disposal is the calculation of garbage volume. In this paper, according to the different landfill conditions of a landfill in Anhui, including: covering soil, overlying HDPE membrane, overlying concrete, etc., combined with the physical differences between the rock mass and the garbage at the bottom of the landfill. The landfill covered with HDPE membrane adopts the transient electromagnetic method, the landfill covered with soil layer adopts the high-density electrical method, and the landfill covered with concrete adopts the combination of transient electromagnetic method and ground penetrating radar. At the same time, Combines the borehole data to determine that the resistivity value of the interface between the garbage and the soil was 29 Ω⋅m. Finally, the sections of multiple survey lines can accomplish three-dimensional stereoscopic that calculate the distribution and actual volume of the garbage. This method is used to determine the final investment cost.
文摘This report evaluates the use of electrical method and borehole data to investigate the subsurface to delineate the groundwater potential in Enugu metropolis and the environs, south-eastern Nigeria other than rely only on resistivity method w</span><span style="font-family:Verdana;">hich could lead to interpretation error. Integrating these 2 data sets is key in this study. The study area is located in the Anambra Basin and is underlain by Nkporo/Enugu Shale which is overlain by the Mamu Formation. It is bounded by Latitudes 6</span><span style="font-family:Verdana;"><span style="white-space:nowrap;">°</span>2 0'00</span></span><span style="font-family:Verdana;">"</span><span style="font-family:Verdana;">N to 6<span style="white-space:nowrap;">°</span>30'00</span><span style="font-family:Verdana;">"</span><span style="font-family:Verdana;">N and Longitudes 7<span style="white-space:nowrap;">°</span>25'00</span><span style="font-family:Verdana;">"</span><span style="font-family:Verdana;">E to 7<span style="white-space:nowrap;">°</span>35'00</span><span style="font-family:Verdana;">"</span><span style="font-family:""><span style="font-family:Verdana;">E and covers surface area of about 342 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">. Thirty</span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">one vertical electrical soundings (VES) were carried out across the area using the Schlumberger electrode array with current electrode separation from 2 to 500 m to identify the depths and resistivity values of the identified geo-electric layers. Through data analysis using WinResist software, the apparent resistivity, thicknesses and depths and the thicknesses of the aquifers were generated. The resistivity</span><span style="font-family:""> </span><span style="font-family:Verdana;">and depths were modelled to generate resistivity map and depth map. The resistivity of the aquiferous zone within the study area varie</span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;"> from 20.55</span><span style="font-family:""> - </span><span style="font-family:Verdana;">427.8 ohm-m at depths of between 10.7</span> - <span style="font-family:Verdana;">40.05 m. Depth to the water table appears to be shallow at the south western part of the map. The interpreted geo-electric layers show a sequence of lateritic top soil, shale, sand and shale. The frequency distribution of the VES curves generated shows the presence of 3 to 5 layers with HK type as the highest. Also, a 2D model was generated using the correlation of VES to VES data and borehole data to VES data to show the underlying stratigraphy beneath the study area as well as the direction of ground water flow. Result of the VES curve analysis reveal</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> that the sub-surface is underlain by three lithological layers namely: lateritic top soil, shale, sand and shales with NW direction of groundwater flow from the 2D model. Groundwater prospective zones can be seen along NW, SW and central parts of the study area which have low resistivity values.
基金Funded by the National Natural Science Foundation of China(51165006)
文摘A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.
基金Funded by the National Natural Science Foundation of China(No.51165006)the Universities in Hubei Province Outstanding Young Scientific and Technological Innovation Team(No.T201626)
文摘Carbon nanotubes(CNTs) were synthesized by the electric heating catalytic chemical deposition method(CCVD) using acetylene(C2H2) as the carbon source and nitrogen(N2) as carrier gas,and nickel catalyst was loaded by electroplating.The electric heating method,as a new method,electrifies the carbon fiber directly by using its conductivity.The morphology and structure of CNTs were characterized by SEM and TEM,and the surface properties of carbon fibers before and after the growth of CNT were characterized by Raman spectroscopy.The experimental results show that the electric heating method is a new method to produce CNT,and can grow a large number of CNTs in a short time,the crystallization degree and surface average crystallite size of carbon fiber increased after the growth of CNT on it.In addition,electroplating loading catalyst can also be used as an ideal loading way,which can control the number,shape,and distribution of nickel particles by controlling the plating time.
文摘According to computer numerical simulation for measuring atmosphere carbon potential by electric resistance method (hot-wire method) and the experimental data, the paper point out that the measuring result dose not directly reflect the atmosphere carbon potential (Cg) but the average carbon content, and as a result, the change of electric resistance obviously lag to that of the atmosphere carbon potential. In order to correctly control the carbon potential by electric resistance method, the authors bring forward a function which is a better expression for the relationship between the average carbon content of the wire and the atmosphere carbon potential and ensures good carbon potential control.
基金Supported by National Key Research and Development Program of China(2016YFB0100605)。
文摘The traditional measurement method was inaccurate to evaluate the motor controller efficiency,which the measurement efficiency value could be more than 100%in practical testing experiments.To deal with this issue,an improved electrical measurement method for the motor controller efficiency is proposed in this paper,which is established by analyzing the power loss distribution and phase currents of the motor controller.It is demonstrated that the SiC MOSFET chips are the main power loss devices in the motor controller,accounting for more than 93.1%of the total power loss.The accuracy of the proposed method is compared with the traditional method in simulation.It shows that the test error of the efficiency obtained by the traditional method fluctuates on a large scale,which varied from 0.094%to 1.911%.Compared with the traditional method,the test error of the proposed method appears to be less than 0.083%,which provides significant guidance for the motor controller efficiency test and design.
文摘In order to study evolution laws of tensile fractures in a coal mining area, based on the classification of the fractures formed by mining, a physical simulation test was carried out to simulate the dynamic evolution process of tensile fractures in coal mining areas. The results showed that after the coal in the mining area was mined, the mining area underwent obvious movement and deformation and forms tensile fractures. As the min-ing working face was advanced, the tensile fractures underwent the dynamic process of generation, development and closure. The changing curves of density of tensile fractures with the increase of mining length of the working face liked a ladder (it increased slowly and then rapidly) and then had two peaks (the second peak was higher than the first peak).
文摘In the light of its negative impacts on the environment and human health, conventional agriculture is currently facing new challenges;for example, reducing pesticide reliance, improving biodiversity, adapting to climate change and reconciling winegrowers with consumers, which require changes to be made to vineyard management. A shift towards more sustainable agriculture via the development of agroecological systems may be key to meeting these environmental, economic and social challenges. This study aimed to evaluate the performance of existing viticultural systems, as well as that of three new scenarios that we built to change conventional vine production systems and their related practices. The end aim is to adopt the principles of agroecology, and more virtuously, to ensure that vine production remains in line with societal expectations. First, thirty-eight different viticultural systems were chosen. Three realistic scenarios for changing these production systems were then built by working with stakeholders and incorporating the best practices that had been identified in the vineyard. Conventional practices were optimised in the first scenario and an agroecological approach was adopted for the other two scenarios: an Agroecological scenario (using synthetic chemicals) and an Agroecological-Bio scenario (organic system). All three scenarios were based on a combination of good practices which contribute to enhancing vineyard biodiversity, and which thus restore biological regulation and in turn reduce pesticides. The viticultural systems performances have been evaluated with a methodology involving multicriteria decision aid using ELECTRE Tri-C and ELECTRE III methods. Seven evaluation criteria were selected which covered socio-economic performance (economic profitability, workload and system complexity) and environmental performance (pesticide pressure, pesticide ecotoxicity, agroecological practices and pesticide drift). The best performances were achieved by the two agroecological scenarios, and this methodology can be adaptable to different production systems everywhere in different viticultural regions.
文摘This paper is devoted to the analysis of the nonlinear Stability of a clamped rodcarrying electric current in the magnetic field which is produced by the current frowingin a pair of inifinitely long parallel rigid wires. The natural State of the rod is in theplane of the wires and is equidistant from them.Firstly under the assumption of apatial deformation, the governing equations of the problem are derived, and the linearizedproblem and critical currents are discussed. Secondly, it ls proved that the buckledstates of the rod are always in planes. Finally. the global responses of the bifurcationproblem of the rod are compuled numerically and the distributions of the deflections.axial forces and bending monents are obtained. The results show that the buckledslates of the rod may be either supercritical or Subcritical. depending on the distancebetween the rod and the wires. Furthermore, it is found that -there exists a limit pointon the branch solution of the supercritical buckled State. This is distinctively differentfrom the buckled slate of the elastic compressive rods.
基金This work was financially supported by National Natural Science Foundation of China(11902204)Liaoning Revitalization Talents Program(XLYC2007118)+3 种基金Aeronautical Science Foundation(201903054001)Shenyang Youth Technological Innovation Talent Project(RC200030),Shenyang Natural Science Foundation Project(22-315-6-07)Education Department of Liaoning Province’s Item(LJKQZ 20222263)Basic Scientific Research Project of Liaoning Provincial Department of Education(LJKMZ20220566).
文摘Composite structures are sensitive to impact damage in practical engineering.Electric resistance change method(ERCM)is an ideal technique for damage monitoring of composite structures.Due to the anisotropy of fiber-resin matrix composites,impact location monitoring is difficult,and research on impact location of fiber composite laminates(FRPs)is limited.A preparation method of MXene/CNT/CuNps thin film sensor is proposed.According to the modeling simulation and theoretical calculation,the resistance change characteristics of the thin film sensor are obtained,the relationship between the impact distance and the resistance change is established,and the sensor array is designed.A three-point localization algorithm and a weight function compensation localization algorithm are proposed,which can improve the imaging accuracy of the impact position.The impact point location was observed and analyzed using ultrasonic C-scan technology.The results show that the weight function compensation positioning algorithm can accurately locate the impact of the composite structure,and the error in the X direction is 7.1%,the error in the Y direction is 0.03%,which verifies the effectiveness of the method.
文摘Background Despite outstanding antiplatelet properties of aspirin and clopidogrel, some patients taking these drugs continue to suffer complications. Antiplatelet resistance appears to be a new prognostic factor in acute coronary syndrome patients for clinical events associated with stent thrombosis (ST). However, there is no optimal method to identify it and assess its correlation to clinical outcomes. This study sought to evaluate the predictive value of antiplatelet resistance assessed by whole blood impedance aggregometry for the risk of early ST in patients with acute coronary syndrome who underwent coronary stenting. Methods Platelet responses to aspirin and clopidogrel in 86 patients with acute coronary syndrome were measured by whole blood impedance aggregometry. Spontaneous platelet aggregation was defined as antiplatelet resistance identified by the increased electrical impedance. The clinical endpoint was early stent thrombosis during 30-day follow-up after coronary stenting. Results The prevalence of aspirin resistance, clopidogrel resistance and dual resistance of combined clopidogrel and aspirin resistance were 19.8%, 12.8% and 5.8% respectively. Diabetes, female and higher platelet counts were more frequently detected in clopidogrel-resistant and dual-resistant patients. During 30-day follow-up, the patients with clopidogrel resistance and dual resistance had higher incidence of early stent thrombosis (18.2% vs. 1.3%, 40.0% vs. 1.2%, P 〈0.05). Binary Logistic Regression analysis indicated that dual resistance remained an independent predicator for early stent thrombosis (odds ratio 34.064, 95% CI 1.919-604.656, P=-0.016). Conclusions Antiplatelet resistance assessed by whole blood impedance aggregometry is paralleled to clinical events, and dual antiplatelet resistance is an independent predicator for early stent thrombosis in patients with acute coronary syndrome. As a physiological assessment of platelet reactivity, whole blood impedance aggregometry is a convenient and accurate option for measurin.q antiplatelet resistance and hence predicting early stent thrombosis.
基金Acknowledgements We thank the financial support provided by the National Natural Science Foundation of China (Grant Nos. 21206038 and 51504099), the Specialized Research Fund for the Doctoral Program of Higher Education (New Teachers) (Grant No. 20120074120014), and the Fundamental Research Funds for the Central Universities.
文摘Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and used to calculate electric field at the steady state through the finite element analysis. Based on the simulation of the electric field, the operational and structural parameters, such as the current intensity, anode thickness, cathode thickness, and anode-cathode distance (ACD), were investigated to obtain the minimum cell voltage. The optimization is to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The results indicate that the effect of the current intensity on the voltage could be ignored and the effect of the ACD is obvious. Moreover, there is a linear decrease between the voltage and the thicknesses of the anode and cathode; and the anodecathode working height also has a significant effect on the voltage.
基金co-supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. 51121004)the Fundamental Research Funds for the Central Universities of China (No. HIT.BRETIV.201315)
文摘Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and numerical modeling are performed in this paper to investigate the behavior of an actively cooled thermal protection system. The analytic estimation is based on the electric analogy method and finite element analysis(FEA) is applied to the numerical simulation. Temperature and stress distributions are obtained for the actively cooled channel walls with three kinds of nickel alloys with or with no thermal barrier coating(TBC). The temperature of the channel wall with coating has no obvious difference from the one with no coating, but the stress with coating on the channel wall is much smaller than that with no coating. Inconel X-750 has the best characteristics among the three Ni-based materials due to its higher thermal conductivity, lower elasticity module and greater allowable stress. Analytic estimation and numerical modeling results are compared with each other and a reasonable agreement is obtained.
文摘The thermal characteristics of high-power AlGaAs/GaAs laser diodes(LDs) at high current(2-10 A)are studied with electrical transient method.The temperature rise increases linearly with the current.The thermal resistance of chip is the largest proportion of total thermal resistance.By increasing the width of the chip from 500 to 800 fim,the temperature rise and thermal resistance decrease by 8.5%and 8.8%,respectively.