Pub Date : 2021-02-23DOI: 10.20998/2074-272X.2021.1.06
K. Korytchenko, O. Shypul, D. Samoilenko, I. Varshamova, А.A. Lisniak, S. Harbuz, K. Ostapov
The aim of the work is to study the influence of the length of the spark gap on energy input into the discharge channel during its gas-dynamic expansion. Methodology. The research is carried out by numerical modeling of the process of spark discharge development at variable values of the discharge gap length and at invariable other discharge conditions. The length of the gap was set in the range from 1 mm to 20 mm. The study was conducted using a numerical model of spark development, which takes into account the processes of nonstationary gas-dynamic expansion of the spark channel, the transient process in the electric circuit, nonequilibrium chemical processes, gas ionization, heat transfer and electrons thermal conductivity. The simulation was performed in atmospheric pressure nitrogen. The calculation was performed for various parameters of the RLC circuit, such as capacitance, inductance, resistance and voltage across the capacitor. Results. The study evaluates the influence of the spark length on the discharge current, the resistance of the spark channel, the energy deposited in the spark channel, and the distribution of thermodynamic parameters of the gas during the development of the spark discharge. It is confirmed that increasing the length of the gap increases the resistance of the spark. The deviation from the linear relationship between the deposited energy or the radiated energy and the length of the spark gap is estimated. Scientific novelty. A linear relationship between the gap length and the deposited energy is revealed when the total energy is above tens of Joules. Deviations from the linear dependence were detected in the discharge circuit when the total energy is below one of Joules. Practical value. The research results allow predicting the effect of the spark gap length on the energy input into the discharge channel under conditions of a slight change in the discharge current. In the conditions of essential change of amplitude of discharge current it is expedient to apply numerical researches for specification of changes in the energy deposited into a spark discharge.
{"title":"Numerical Simulation of Gap Length Influence on Energy Deposition in Spark Discharge","authors":"K. Korytchenko, O. Shypul, D. Samoilenko, I. Varshamova, А.A. Lisniak, S. Harbuz, K. Ostapov","doi":"10.20998/2074-272X.2021.1.06","DOIUrl":"https://doi.org/10.20998/2074-272X.2021.1.06","url":null,"abstract":"The aim of the work is to study the influence of the length of the spark gap on energy input into the discharge channel during its gas-dynamic expansion. Methodology. The research is carried out by numerical modeling of the process of spark discharge development at variable values of the discharge gap length and at invariable other discharge conditions. The length of the gap was set in the range from 1 mm to 20 mm. The study was conducted using a numerical model of spark development, which takes into account the processes of nonstationary gas-dynamic expansion of the spark channel, the transient process in the electric circuit, nonequilibrium chemical processes, gas ionization, heat transfer and electrons thermal conductivity. The simulation was performed in atmospheric pressure nitrogen. The calculation was performed for various parameters of the RLC circuit, such as capacitance, inductance, resistance and voltage across the capacitor. Results. The study evaluates the influence of the spark length on the discharge current, the resistance of the spark channel, the energy deposited in the spark channel, and the distribution of thermodynamic parameters of the gas during the development of the spark discharge. It is confirmed that increasing the length of the gap increases the resistance of the spark. The deviation from the linear relationship between the deposited energy or the radiated energy and the length of the spark gap is estimated. Scientific novelty. A linear relationship between the gap length and the deposited energy is revealed when the total energy is above tens of Joules. Deviations from the linear dependence were detected in the discharge circuit when the total energy is below one of Joules. Practical value. The research results allow predicting the effect of the spark gap length on the energy input into the discharge channel under conditions of a slight change in the discharge current. In the conditions of essential change of amplitude of discharge current it is expedient to apply numerical researches for specification of changes in the energy deposited into a spark discharge.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79102054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-22DOI: 10.15587/1729-4061.2021.225121
N. Ashhepkova
This paper has proposed a program analysis method over the current state of the workspace of an anthropomorphic manipulator using the Mathcad software application package (USA). The analysis of the manipulator workspace helped solve the following sub-tasks: to calculate the limits of the grip reach, to determine the presence of "dead zones" within the manipulator workspace, to build the boundaries of the manipulator workspace. A kinematic scheme of the manipulator typically provides for at least five degrees of mobility, which is why in the three-dimensional Cartesian coordinate system the work zone boundaries represent the surfaces of a complex geometric shape. The author-devised method makes it possible to construct the projections of the boundaries of the manipulator's work zone onto the coordinate planes in the frame of reference associated with the base of the robot.
Using Mathcad's built-in features makes it possible to effectively solve the above sub-tasks without wasting time developing specialized software. The Mathcad software application package provides for the possibility of a symbolic solution to the first problem of the kinematics of an industrial robot, that is, the program generates analytical dependences of the coordinates for special point P (pole) of the grip on the trigonometrical functions of the generalized coordinates. The resulting analytical dependences are used for kinematic and dynamic analysis of the manipulator.
Special features in constructing mathematical models when using the Mathcad software application package have been revealed. Simulating the manipulator movement taking into consideration constraints for kinematic pairs, the drives' power, as well as friction factors, makes it possible to optimize the parameters of the manipulator kinematic scheme.
An example of the analysis of the working space of an anthropomorphic manipulator with five degrees of mobility has been considered.
The reported results could be used during the design, implementation, modernization, and operation of manipulators.
{"title":"Devising a Method to Analyze the Current State of the Manipulator Workspace","authors":"N. Ashhepkova","doi":"10.15587/1729-4061.2021.225121","DOIUrl":"https://doi.org/10.15587/1729-4061.2021.225121","url":null,"abstract":"This paper has proposed a program analysis method over the current state of the workspace of an anthropomorphic manipulator using the Mathcad software application package (USA). The analysis of the manipulator workspace helped solve the following sub-tasks: to calculate the limits of the grip reach, to determine the presence of \"dead zones\" within the manipulator workspace, to build the boundaries of the manipulator workspace. A kinematic scheme of the manipulator typically provides for at least five degrees of mobility, which is why in the three-dimensional Cartesian coordinate system the work zone boundaries represent the surfaces of a complex geometric shape. The author-devised method makes it possible to construct the projections of the boundaries of the manipulator's work zone onto the coordinate planes in the frame of reference associated with the base of the robot.<br><br>Using Mathcad's built-in features makes it possible to effectively solve the above sub-tasks without wasting time developing specialized software. The Mathcad software application package provides for the possibility of a symbolic solution to the first problem of the kinematics of an industrial robot, that is, the program generates analytical dependences of the coordinates for special point P (pole) of the grip on the trigonometrical functions of the generalized coordinates. The resulting analytical dependences are used for kinematic and dynamic analysis of the manipulator.<br><br>Special features in constructing mathematical models when using the Mathcad software application package have been revealed. Simulating the manipulator movement taking into consideration constraints for kinematic pairs, the drives' power, as well as friction factors, makes it possible to optimize the parameters of the manipulator kinematic scheme.<br><br>An example of the analysis of the working space of an anthropomorphic manipulator with five degrees of mobility has been considered.<br><br>The reported results could be used during the design, implementation, modernization, and operation of manipulators.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82511548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Patrick Esser, J. Thorborg, G. Hartmann, W. Schaefer
Additive manufacturing of metal parts is widely used for different alloys and different types of application. During building of the parts, local heating of the powder generates a small melt pool with high thermal gradients followed by rapid solidification. Already solidified material is re-melted and affected by heating when layers are added. The thermal history of the moving heat source and the layer building of the part have a high influence on the formed microstructure, the risk of porosities and evolution of cracks. High stresses and permanent deformations develop during the building process, which lead to large deformations when e.g. the base plate is removed. Heat treatment of the parts is often used to reduce the stress level and to minimize the deformations.
This paper presents an integrated modelling and simulation approach, where results from the additive manufacturing process are used as initial conditions for the subsequent heat treatment process.
An integrated simulation approach has been developed and implemented as a dedicated solution to simulate the sequence of the additive manufacturing process and subsequent heat treatment steps. To get reasonable calculation times multiscale methods have been tested to perform virtual experiments, where the influence of different scanning strategies have been evaluated to optimize temperature distributions and the influence on mechanical performance. A unified creep model is used to describe the mechanical behavior of the material to ensure a consistent description through the large temperature interval and the different levels of time and strain rates.
{"title":"Integrated Modelling and Simulation of the Additive Manufacturing and Heat Treatment Process Chain","authors":"Patrick Esser, J. Thorborg, G. Hartmann, W. Schaefer","doi":"10.2139/ssrn.3785868","DOIUrl":"https://doi.org/10.2139/ssrn.3785868","url":null,"abstract":"Additive manufacturing of metal parts is widely used for different alloys and different types of application. During building of the parts, local heating of the powder generates a small melt pool with high thermal gradients followed by rapid solidification. Already solidified material is re-melted and affected by heating when layers are added. The thermal history of the moving heat source and the layer building of the part have a high influence on the formed microstructure, the risk of porosities and evolution of cracks. High stresses and permanent deformations develop during the building process, which lead to large deformations when e.g. the base plate is removed. Heat treatment of the parts is often used to reduce the stress level and to minimize the deformations.<br><br>This paper presents an integrated modelling and simulation approach, where results from the additive manufacturing process are used as initial conditions for the subsequent heat treatment process.<br><br>An integrated simulation approach has been developed and implemented as a dedicated solution to simulate the sequence of the additive manufacturing process and subsequent heat treatment steps. To get reasonable calculation times multiscale methods have been tested to perform virtual experiments, where the influence of different scanning strategies have been evaluated to optimize temperature distributions and the influence on mechanical performance. A unified creep model is used to describe the mechanical behavior of the material to ensure a consistent description through the large temperature interval and the different levels of time and strain rates.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"241 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89162725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tensile and dilatometric specimens were obtained with longitudinal axis parallel to the building direction. A first set of samples has been directly aged in the as- built state (AB) while a second batch underwent solubilization annealing (SA) at 540°C for 60min just before artificial ageing (AA) at 160°C for 8h. Solubilization caused the precipitation of Si particles, suppressed by the rapid solidification during SLM. Moreover, it caused partial recrystallization leading to a coarser microstructure. The ageing response resulted very different in the two cases, involving a higher starting hardness for the as-built material, showing a markedly higher hardness during the whole process. In the as built (AB) material, isochronal ageing experiments carried out by differential scanning calorimetry showed the precipitation of Mg2Si particles beneath Si, while the same transformations were much less intense in the solubilized sample, due to the lower Si supersaturation. The ageing process raised the yield strength of about 20% compared to the AB material, slightly reducing the fracture elongation.
纵轴平行于建筑方向获得拉伸和膨胀试件。第一批样品在建立状态(AB)下直接时效，第二批样品在160°C下人工时效(AA) 8小时之前在540°C下进行增溶退火(SA) 60分钟。固溶作用导致Si颗粒析出，但被SLM过程中的快速凝固所抑制。此外，它引起部分再结晶，导致较粗的组织。在两种情况下，老化响应的结果非常不同，包括初始硬度较高的建成材料，在整个过程中表现出明显更高的硬度。在as - built (AB)材料中，差示扫描量热法进行的等时时效实验表明，Mg2Si颗粒在Si下析出，而在溶解样品中，由于Si过饱和度较低，相同的转变强度要小得多。与AB材料相比，时效处理使屈服强度提高了约20%，断裂伸长率略有降低。
{"title":"Laser Metal Fused Al Alloy Processed Using Different Heat Treatments","authors":"M. Pellizzari, M. Malfatti, C. Lora","doi":"10.2139/ssrn.3785869","DOIUrl":"https://doi.org/10.2139/ssrn.3785869","url":null,"abstract":"Tensile and dilatometric specimens were obtained with longitudinal axis parallel to the building direction. A first set of samples has been directly aged in the as- built state (AB) while a second batch underwent solubilization annealing (SA) at 540°C for 60min just before artificial ageing (AA) at 160°C for 8h. Solubilization caused the precipitation of Si particles, suppressed by the rapid solidification during SLM. Moreover, it caused partial recrystallization leading to a coarser microstructure. The ageing response resulted very different in the two cases, involving a higher starting hardness for the as-built material, showing a markedly higher hardness during the whole process. In the as built (AB) material, isochronal ageing experiments carried out by differential scanning calorimetry showed the precipitation of Mg2Si particles beneath Si, while the same transformations were much less intense in the solubilized sample, due to the lower Si supersaturation. The ageing process raised the yield strength of about 20% compared to the AB material, slightly reducing the fracture elongation.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74220880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shengcheng Shu, Q. Yuan, W. Dai, Mingliang Wu, Dan Dai, Ke Yang, Bo Wang, Cheng‐Te Lin, Thomas Wuebben, J. Degenhardt, C. Regula, R. Wilken, N. Jiang, Joerg Ihde
Abstract Owing to the unfavorable wetting and density difference between graphene and copper, it remains challenging to achieve homogeneous dispersion of graphene for utilizing the unique nature of graphene in copper matrix composites. Here, we design an in-situ process to fabricate graphene-like carbon (GLC) reinforcing copper matrix composites: GLC can be directly fabricated on commercial copper particles using modified PECVD method followed by vacuum hot pressing, which is high-efficiency and can be massively produced for graphene reinforced metal matrix composites in industrial level. After hot pressing, the GLC with ultralow content (170 to 350 ppm) can be uniformly dispersed and tightly embedded within the copper matrix. A remarkable thermal conductivity enhancement efficiency of 85% and enhanced thermal conductivity (439 W m−1 K−1), accompanied by the higher wear resistance, can be obtained in our GLC reinforced copper matrix composites. In actual arc ablation performance measurement, the breakdown strength and relative arc ablation resistance of GLC/Cu composites can be significantly improved by 106.5% and 33.3% than pure copper, respectively, demonstrating GLC/Cu composites a promising candidate for application as high voltage electrical contacts.
由于石墨烯和铜之间的湿润性和密度差异，利用石墨烯在铜基复合材料中的独特性质，实现石墨烯的均匀分散仍然是一个挑战。本研究设计了一种原位制备类石墨烯碳(GLC)增强铜基复合材料的工艺:采用改进的PECVD方法直接在商用铜颗粒上制备类石墨烯碳(GLC)，然后进行真空热压，该工艺效率高，可批量生产工业级石墨烯增强金属基复合材料。热压后，超低含量(170 ~ 350 ppm)的GLC可均匀分散，并紧密嵌入铜基体中。GLC增强铜基复合材料的导热系数提高了85%，导热系数提高了439 W m−1 K−1，并具有较高的耐磨性。在实际电弧烧蚀性能测试中，与纯铜相比，GLC/Cu复合材料的击穿强度和相对抗电弧烧蚀性能分别提高了106.5%和33.3%，表明GLC/Cu复合材料在高压电触点领域具有广阔的应用前景。
{"title":"In-Situ Synthesis of Graphene-Like Carbon Encapsulated Copper Particles for Reinforcing Copper Matrix Composites","authors":"Shengcheng Shu, Q. Yuan, W. Dai, Mingliang Wu, Dan Dai, Ke Yang, Bo Wang, Cheng‐Te Lin, Thomas Wuebben, J. Degenhardt, C. Regula, R. Wilken, N. Jiang, Joerg Ihde","doi":"10.2139/ssrn.3805231","DOIUrl":"https://doi.org/10.2139/ssrn.3805231","url":null,"abstract":"Abstract Owing to the unfavorable wetting and density difference between graphene and copper, it remains challenging to achieve homogeneous dispersion of graphene for utilizing the unique nature of graphene in copper matrix composites. Here, we design an in-situ process to fabricate graphene-like carbon (GLC) reinforcing copper matrix composites: GLC can be directly fabricated on commercial copper particles using modified PECVD method followed by vacuum hot pressing, which is high-efficiency and can be massively produced for graphene reinforced metal matrix composites in industrial level. After hot pressing, the GLC with ultralow content (170 to 350 ppm) can be uniformly dispersed and tightly embedded within the copper matrix. A remarkable thermal conductivity enhancement efficiency of 85% and enhanced thermal conductivity (439 W m−1 K−1), accompanied by the higher wear resistance, can be obtained in our GLC reinforced copper matrix composites. In actual arc ablation performance measurement, the breakdown strength and relative arc ablation resistance of GLC/Cu composites can be significantly improved by 106.5% and 33.3% than pure copper, respectively, demonstrating GLC/Cu composites a promising candidate for application as high voltage electrical contacts.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84437715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yanghui Li, Peng Wu, Xiang Sun, Weiguo Liu, Yongchen Song
Unlike the conceptual models based on idealistic assumptions, the natural hydrate spatial distribution in sediments is multitype and presents different coalescence degrees, which could greatly influence its geomechanical behavior. In this study, we present pore-scale triaxial test results for hydrate-bearing sediments with different hydrate spatial distributions for the first time. The results show that both specimens exhibit strain-softening, and the specimen in which the hydrate present a dispersed distribution yields later and shows a larger peak strength and weaker strain-softening. The localized deformation of the specimen in which the hydrates present a dispersed distribution develops slower, and the shear band is steeper and thinner. During the shearing process, the cementation failure in the specimen which the hydrate present a dispersed distribution develops faster. However, the changing rate of the pore space characteristic seems to not be affected by the hydrate spatial distribution. Moreover, the specimen in which the hydrate present a dispersed distribution has a larger hydrate-sand interfacial area. Along with the axial loading, the hydrate-sand interfacial area would increase rapidly and even straighten. Further loading would lead to the complete failure of the hydrate-cemented structure, which would lead to the slowing of the increase in the hydrate-sand interfacial area.
{"title":"Mechanical Behaviors of Hydrate-Bearing Sediment with Different Cementation Spatial Distributions: Insight from Pore Scale","authors":"Yanghui Li, Peng Wu, Xiang Sun, Weiguo Liu, Yongchen Song","doi":"10.2139/ssrn.3779557","DOIUrl":"https://doi.org/10.2139/ssrn.3779557","url":null,"abstract":"Unlike the conceptual models based on idealistic assumptions, the natural hydrate spatial distribution in sediments is multitype and presents different coalescence degrees, which could greatly influence its geomechanical behavior. In this study, we present pore-scale triaxial test results for hydrate-bearing sediments with different hydrate spatial distributions for the first time. The results show that both specimens exhibit strain-softening, and the specimen in which the hydrate present a dispersed distribution yields later and shows a larger peak strength and weaker strain-softening. The localized deformation of the specimen in which the hydrates present a dispersed distribution develops slower, and the shear band is steeper and thinner. During the shearing process, the cementation failure in the specimen which the hydrate present a dispersed distribution develops faster. However, the changing rate of the pore space characteristic seems to not be affected by the hydrate spatial distribution. Moreover, the specimen in which the hydrate present a dispersed distribution has a larger hydrate-sand interfacial area. Along with the axial loading, the hydrate-sand interfacial area would increase rapidly and even straighten. Further loading would lead to the complete failure of the hydrate-cemented structure, which would lead to the slowing of the increase in the hydrate-sand interfacial area.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80143745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-29DOI: 10.21303/2461-4262.2021.001608
Ugur Ulusoy, H. Kurşun
Zinc is a key beneficiary of economic development for the developing countries. While the global zinc mine production in 2019 was recorded as 13 million tons, the value of zinc mined in 2019, based on zinc contained in concentrate, was about $2.1 billion. Sphalerite or zinc blende (ZnS), which is the main source of zinc, provides more than 90 % of zinc productions today. Beneficiation is usually carried out by flotation to produce marketable concentrates (45–55 %Zn). The flotation, which is the most widely used separation process at fine sizes for the concentration of low grade complex Pb-Cu-Zn ores plays an important role in the global economy. In any concentration plant employing flotation technique huge quantity of ores are being processed. Thus, any increments in the flotation recovery are important to get higher profits and to ensure that resources are utilized optimally. In this review, a comparative evaluation was made between mechanical flotation (MF) [1] and column (CF) [2] cells with or without ultrasonic pre-treatment (UP) for zinc recovery from lead-zinc-copper ore and the effect of UP on the MF and CF experiments were investigated at the optimized conditions. When compared with the optimized parameters, UP increased zinc grade and recovery for both MF and CF techniques as supported by XRD patterns. Besides, the best zinc grade and recovery was obtained by UP with CF technique. So that, sphalerite mineral can be effectively beneficiated to produce saleable zinc concentrate product and UP with CF will lead to a higher metallurgical gains and improvements to Net Smelter Return (NSR). This positive effect of ultrasound, which is safe and eco-friendly, on the zinc flotation by both mechanical cell and column cell regarding zinc grade and recovery is in good agreement with the previous published works in the literature
{"title":"Review: Comparison of Ultrasonically Aided Zinc Beneficiation by Mechanical Flotation and Column Flotation Cell","authors":"Ugur Ulusoy, H. Kurşun","doi":"10.21303/2461-4262.2021.001608","DOIUrl":"https://doi.org/10.21303/2461-4262.2021.001608","url":null,"abstract":"Zinc is a key beneficiary of economic development for the developing countries. While the global zinc mine production in 2019 was recorded as 13 million tons, the value of zinc mined in 2019, based on zinc contained in concentrate, was about $2.1 billion. Sphalerite or zinc blende (ZnS), which is the main source of zinc, provides more than 90 % of zinc productions today. Beneficiation is usually carried out by flotation to produce marketable concentrates (45–55 %Zn). The flotation, which is the most widely used separation process at fine sizes for the concentration of low grade complex Pb-Cu-Zn ores plays an important role in the global economy. In any concentration plant employing flotation technique huge quantity of ores are being processed. Thus, any increments in the flotation recovery are important to get higher profits and to ensure that resources are utilized optimally. In this review, a comparative evaluation was made between mechanical flotation (MF) [1] and column (CF) [2] cells with or without ultrasonic pre-treatment (UP) for zinc recovery from lead-zinc-copper ore and the effect of UP on the MF and CF experiments were investigated at the optimized conditions. When compared with the optimized parameters, UP increased zinc grade and recovery for both MF and CF techniques as supported by XRD patterns. Besides, the best zinc grade and recovery was obtained by UP with CF technique. So that, sphalerite mineral can be effectively beneficiated to produce saleable zinc concentrate product and UP with CF will lead to a higher metallurgical gains and improvements to Net Smelter Return (NSR). This positive effect of ultrasound, which is safe and eco-friendly, on the zinc flotation by both mechanical cell and column cell regarding zinc grade and recovery is in good agreement with the previous published works in the literature","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74063285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract To reduce the initial peak force (IPF) and improve the crushing force efficiency (CFE) of tubular energy absorbers, buckling induced tubes (BITs) were designed based on modal analysis of straight-walled triangular tubes. The crushing mechanism of the BIT under quasi-static compression was revealed through finite element analysis (FEA) and theoretical analysis. It is found that the BIT can be folded according to specific mode by cleverly presetting the convex-concave structure form. The larger is the amplitude of the buckling wave, the smaller is the IPF, as well as the mean crushing force (MCF). But the CFE is greatly improved. Compared with straight tubes, high-order mode BITs have lower IPF but greater MCF, CFE and specific energy absorption (SEA). A simplified model based on Shanley model was proposed to predict the IPF of the BIT. The MCF was predicted by improved super folding element (SFE) and simplified super folding element (SSFE) models. End buckling induction mechanism is introduced as an efficient way to reduce the IPF, but keep the MCF and enhance the CFE simultaneously.
{"title":"Axial Crushing Behaviors of Buckling Induced Triangular Tubular Structures","authors":"J. Dong, Weiwei Li, Hualin Fan","doi":"10.2139/ssrn.3805246","DOIUrl":"https://doi.org/10.2139/ssrn.3805246","url":null,"abstract":"Abstract To reduce the initial peak force (IPF) and improve the crushing force efficiency (CFE) of tubular energy absorbers, buckling induced tubes (BITs) were designed based on modal analysis of straight-walled triangular tubes. The crushing mechanism of the BIT under quasi-static compression was revealed through finite element analysis (FEA) and theoretical analysis. It is found that the BIT can be folded according to specific mode by cleverly presetting the convex-concave structure form. The larger is the amplitude of the buckling wave, the smaller is the IPF, as well as the mean crushing force (MCF). But the CFE is greatly improved. Compared with straight tubes, high-order mode BITs have lower IPF but greater MCF, CFE and specific energy absorption (SEA). A simplified model based on Shanley model was proposed to predict the IPF of the BIT. The MCF was predicted by improved super folding element (SFE) and simplified super folding element (SSFE) models. End buckling induction mechanism is introduced as an efficient way to reduce the IPF, but keep the MCF and enhance the CFE simultaneously.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89865068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Boubeche, Ningning Wang, Jianping Sun, P. Yang, Lingyong Zeng, Yiyi He, S. Luo, Jinguang Cheng, Huixia Luo
The interplay between superconductivity (SC) and the charge density wave (CDW)-like order in CuIr2Te4 is systematically explored through Se substitution for Te site through the powder X-ray diffraction (PXRD), magnetic susceptibility, resistivity measurements and heat capacity. CuIr2Te4-XSex (0 ≤ x ≤ 0.5) compounds retain the same structure as the host CuIr2Te4. The unit cell parameters a and c decrease linearly with increasing Se content. Tc exhibits a weak dome-like variation as substituting Te by Se with the maximum Tc = 2.83 K for x = 0.1 followed by suppression in Tc and simultaneous decrease of the superconducting volume fraction. Unexpectedly, the CDW-like transition (TCDW) is suppressed with lower Se doping (0.025 ≤ x ≤ 0.2) but re-emerge at higher doping (0.25 ≤ x ≤ 0.5). We propose that it arises from the disorder effect by chemical doping. The lower and the upper critical field and these compounds are also addressed.
{"title":"Anomalous Charge Density Wave State Evolution and Dome-Like Superconductivity in CuIr 2Te 4-XSe x","authors":"M. Boubeche, Ningning Wang, Jianping Sun, P. Yang, Lingyong Zeng, Yiyi He, S. Luo, Jinguang Cheng, Huixia Luo","doi":"10.2139/ssrn.3761880","DOIUrl":"https://doi.org/10.2139/ssrn.3761880","url":null,"abstract":"The interplay between superconductivity (SC) and the charge density wave (CDW)-like order in CuIr2Te4 is systematically explored through Se substitution for Te site through the powder X-ray diffraction (PXRD), magnetic susceptibility, resistivity measurements and heat capacity. CuIr2Te4-XSex (0 ≤ x ≤ 0.5) compounds retain the same structure as the host CuIr2Te4. The unit cell parameters a and c decrease linearly with increasing Se content. Tc exhibits a weak dome-like variation as substituting Te by Se with the maximum Tc = 2.83 K for x = 0.1 followed by suppression in Tc and simultaneous decrease of the superconducting volume fraction. Unexpectedly, the CDW-like transition (TCDW) is suppressed with lower Se doping (0.025 ≤ x ≤ 0.2) but re-emerge at higher doping (0.25 ≤ x ≤ 0.5). We propose that it arises from the disorder effect by chemical doping. The lower and the upper critical field and these compounds are also addressed.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85275366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A horizontal cell for the exfoliation of graphite turns gravity from a burden into an ally. Our cell and method allow for the convenient exfoliation of graphite in powder form. Very mild conditions (just 3 minutes at just 3 Volts suffice) save time and energy. High-quality few-layers graphene with negligible oxygen content produced.
{"title":"New and Improved Cell and Method for the Production of Graphene by Electrochemical Exfoliation of Graphite Powder","authors":"Daniel Rueda-García, P. Gómez‐Romero","doi":"10.2139/ssrn.3940879","DOIUrl":"https://doi.org/10.2139/ssrn.3940879","url":null,"abstract":"A horizontal cell for the exfoliation of graphite turns gravity from a burden into an ally. Our cell and method allow for the convenient exfoliation of graphite in powder form. Very mild conditions (just 3 minutes at just 3 Volts suffice) save time and energy. High-quality few-layers graphene with negligible oxygen content produced.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73942835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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