The glass-forming ability(GFA)of metallic glasses is a key scientific challenge in their development and application,with compositional dependence playing a crucial role.Experimental studies have demonstrated that the...The glass-forming ability(GFA)of metallic glasses is a key scientific challenge in their development and application,with compositional dependence playing a crucial role.Experimental studies have demonstrated that the addition of specific minor elements can greatly enhance the GFA of parent alloys,yet the underlying mechanism remains unclear.In this study,we use the ZrCuAl system as a model to explore how the addition of minor Al influences the crystallization rate by modulating the properties of the crystal-liquid interface,thereby affecting the GFA.The results reveal that the minor addition of Al significantly reduces the crystal growth rate,a phenomenon not governed by particle density fluctuations at the interface.The impact of minor element additions extends beyond a modest increase in crystal-unfavorable motifs in the bulk supercooled liquid.More importantly,it leads to a significant enrichment of these motifs at the crystal-supercooled liquid interface,forming a dense topological network of crystal-unfavorable structures that effectively prevent the growth of the crystalline interface and enhance GFA.Our results provide valuable insights for the design and development of high-performance metallic glasses.展开更多
Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish...Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn^(2+) deposition reaction and induces phase and structure change of the deposited manganese oxide(Zn_(2)Mn_(3)O_8·H_(2)O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm^(-2) after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn^(2+), and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability.展开更多
The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-f...The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-forming ability and magnetic properties of Fe_(86-x)Y_xB_7C_7(x = 0, 5, 10 at.%) amorphous alloys via both experiments and ab initio molecular dynamics simulations. Furthermore, we explore the correlation between local atomic structures and properties. Our results demonstrate that an increased Y content in the alloys leads to a higher proportion of icosahedral clusters, which can potentially enhance both glass-forming ability and thermal stability. These findings have been experimentally validated. The analysis of the electron energy density and magnetic moment of the alloy reveals that the addition of Y leads to hybridization between Y-4d and Fe-3d orbitals, resulting in a reduction in ferromagnetic coupling between Fe atoms. This subsequently reduces the magnetic moment of Fe atoms as well as the total magnetic moment of the system, which is consistent with experimental results. The results could help understand the relationship between atomic structure and magnetic property,and providing valuable insights for enhancing the performance of metallic glasses in industrial applications.展开更多
The aeromechanical st ability for the coupled rotor/fuselage system of helicopters in forward flight i s investigated. The periodic time-varying equations of motion are developed thr ough building a new 24DOF coupled ...The aeromechanical st ability for the coupled rotor/fuselage system of helicopters in forward flight i s investigated. The periodic time-varying equations of motion are developed thr ough building a new 24DOF coupled rigid/elastic blended element based on the fle xible multibody system theory in this paper. It accounts for the effects of prec one, sweep, and the moderately large elastic deflections on the blade and elasti city of shaft and fuselage of the helicopter. The dynamic coupling between the r igid motion of blades about the flap, lag and pitch hinges of articulated rotor and moderately large elastic deflections are included. There is no restriction o n the rotation amplitudes of flap, lag and pitch in the formulation. The stabili ty of periodic solution is studied using the Floquet theory. The transition matr ix is calculated by the Newmark integration method. The aeromechanical stability of a new helicopter is studied. The results show that it is stable in the given forward flight. But the instability arises with the decrease of the bending and torsion stiffness of the shaft.展开更多
English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment accordi...English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment according to our students' practical life in order to improve and enhance their interest in English studying, to encourage them to practice English during their daily life and to cultivate their ability to communicate in English.展开更多
Nowadays, the role of listening course is changed and listening teaching begins to gain high priority in foreign language learning and teaching. However, the English level of students in China is still poor, especiall...Nowadays, the role of listening course is changed and listening teaching begins to gain high priority in foreign language learning and teaching. However, the English level of students in China is still poor, especially in the northwest of Guangxi. One of the reasons is that teachers in senior high schools have a tendency to ignore listening, because they think that listening is time-consumed. They have to finish the teaching scheme punctually, though listening is the basic and important skill among the other three skills, listening teaching gains no large progress.展开更多
Based on the literature review of learner autonomy,this paper analyses the necessity and importance of cultivating autonomous listening ability for non-English majors.Then,it presents some practical ways of cultivatin...Based on the literature review of learner autonomy,this paper analyses the necessity and importance of cultivating autonomous listening ability for non-English majors.Then,it presents some practical ways of cultivating autonomous listening ability of non-English majors.展开更多
English for Careers is a public course for non-English majors,whose objectives are to develop students’basic language skills for work-related activities:listening,reading,speaking,and writing.As far as the four skill...English for Careers is a public course for non-English majors,whose objectives are to develop students’basic language skills for work-related activities:listening,reading,speaking,and writing.As far as the four skills are concerned,most students in higher vocational colleges have the very poor speaking ability.How to improve students’speaking ability is a hard and urgent task for English teachers.This article sets out to analyze the reasons for this problem in English for Careers.Then,based on the second language acquisition and current teaching theory,ways of improving students’speaking ability are suggested.展开更多
In this paper we work with the ordinary diffential equation u′′ u3 = 0 and obtain some interesting phenomena concerning blow-up, blow-up rate, life-spann, zeros and critical points of solutions to this equation.
Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicat...Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicated that, compared with petrodiesel, biodiesel was more liable to promote oxidation degradation of diesel oils, leading to worse oxidative stability, detergency and antiwear ability of the oils.展开更多
This paper is aimed at studying the effect of reading-based writing instruction on the improvement of senior three students’writing capability.By analyzing students’reading materials from the sample test papers,stud...This paper is aimed at studying the effect of reading-based writing instruction on the improvement of senior three students’writing capability.By analyzing students’reading materials from the sample test papers,students are able to notice the distinctive characteristics of the target language ranging from words,expressions,sentence structures and paragraph structures,which is beneficial to students’writing.展开更多
The wetting heat and contact angle of sixteen coal samples were determined and the slurry-forming ability of coal were researched. Comparing the relationship of the wetting heat and contact angle with the slurry-formi...The wetting heat and contact angle of sixteen coal samples were determined and the slurry-forming ability of coal were researched. Comparing the relationship of the wetting heat and contact angle with the slurry-forming ability or coal, the auther has found out that the slurry-forming ability of coal can be measured by the wetting heat.展开更多
In this paper, we work with the ordinary differential equation n^2u （n）＂ = u（n）^p and obtain some interesting phenomena concerning, boundedness, blow-up, blow-up rate, life-span of solutions to those equations.
The miombo woodland is one of the most extensive woodlands in Africa, supporting livelihoods based on biomass fuel for millions of rural people. However, there are growing concerns about the sustainability of harvesti...The miombo woodland is one of the most extensive woodlands in Africa, supporting livelihoods based on biomass fuel for millions of rural people. However, there are growing concerns about the sustainability of harvesting for biomass fuel （mainly charcoal）. Thus, the aim of this study was to examine whether regeneration by coppice is a viable option for sustainably managing miombo woodlands for biomass fuel production. We tested the hypotheses that （1） species, stump diameter, stump height and time since cutting significantly affect the number of sprouts per cut stump （coppice density） and mean sprout height （shoot vigour） and （2） higher coppice density reduces shoot vigour due to competition among coppice shoots in a given stump. In an inventory in areas that were harvested for charcoal production by the local people, 369 stumps of 11 species were recorded with mean coppice stumps ranged from 6 to 84. The mean coppice density ranged from 5 to 8 shoots per stump while the mean height of coppice shoots ranged from 46 to 118 cm with marked interspecific variations. Stump size was signifi- cantly and positively correlated with coppice density for some of the species, but not with shoot vigour for the majority of the species. However, shoot vigour was significantly positively correlated to time since cutting of trees for nearly half of the species. Coppice density had a significant negative correlation with shoot vigour for two species, and a positive correlation for one species. In conclusion, the results provide evidence about the importance of coppice management as a win-win strategy for sustaining charcoal-based rural livelihoods and recovering the miombo woodland ecosystem.展开更多
The heredity of clusters in rapidly cooled(Zr_(50)Cu_(50))_(100-x)Al_x melts and its correlation with glass-forming ability(GFA)are studied via molecular dynamics simulations.Pair distribution function and the largest...The heredity of clusters in rapidly cooled(Zr_(50)Cu_(50))_(100-x)Al_x melts and its correlation with glass-forming ability(GFA)are studied via molecular dynamics simulations.Pair distribution function and the largest standard cluster(LSC)are adopted to characterize the local atomic structures in the(Zr_(50)Cu_(50))_(100-x)Al_(x)systems.The[12/555]icosahedra and their medium-range order(IMRO)play an important role in forming(Zr_(50)Cu_(50))_(100-x)Al_(x)metallic glasses(MGs).The fraction of[12/555],the number of IMRO,and the maximum size of IMRO in MGs increase significantly with increasing x.A tracking study further reveals that the configuration heredity of icosahedral clusters starts from supercooled liquids.No direct correlation exists between the GFA and the onset temperature of continuous or stated heredity.Instead,a larger hereditary supercooled degree of icosahedra matches with better GFA of Al-doped Zr_(50)Cu_(50)alloys.展开更多
A small amount of Ni was added into the binary Gd50Co50 amorphous alloy to replace Gd in order to obtain ternary Co50Gd50-xNx(x=1,2,and 3)amorphous alloys.Compared to the binary Gd50Co50 amorphous alloy,the Co50Gd50-x...A small amount of Ni was added into the binary Gd50Co50 amorphous alloy to replace Gd in order to obtain ternary Co50Gd50-xNx(x=1,2,and 3)amorphous alloys.Compared to the binary Gd50Co50 amorphous alloy,the Co50Gd50-xNx amorphous alloys show an enhanced Curie temperature(TC)with a weakened formability.The maximum magnetic entropy change(-Δ^Smpeak)of the Co50Gd50-xNx amorphous alloys is found to decrease with the increasing TC.The adiabatic temperature rise(ΔTad)of the Co50Gd47Ni3 amorphous alloy is superior to that of the Fe-based metallic glasses at room temperature.The variation of the TC and-Δ^Smpeak of the Gd50Co50 amorphous alloy with Ni addition,and the mechanism involved,were discussed.展开更多
To overcome the shortcomings of pouring sands, a thickener with the ability to suspend sands was developed. It is mixed with sands to form densified slurry, and can insure the sands against deposition, jamming pipelin...To overcome the shortcomings of pouring sands, a thickener with the ability to suspend sands was developed. It is mixed with sands to form densified slurry, and can insure the sands against deposition, jamming pipelines and de- hydration. The chemical structure of the thickener is introduced in this paper and the production process is studied. The main processes include immersion, decomposition, dilution and addition of additives. In order to produce a thickener with high viscosity to suspend sands, key factors must be controlled in each process: the immersion time is 2 h; the mass fraction of formaldehyde is 0.01% and mass of NaCO3 accounts for 15% of dry material; the water temperature is 65 ℃ in summer and 72 ℃ in winter and the decomposition time is 2 h in the reaction; the densified decomposition so- lution should be diluted to 1% mass fraction; the additives of calcium ions and pH indicators must be added to the di- luted liquid; the mass fraction of CaCl2 is 0.048% and the pH value of the solution is 7.5. The thickener is a gel with three-dimensional network structure, a liquid with non-Newtonian behaviour and the characteristics of pseudo-plastic material, a solution with little resistance and the ability to revive its oral primary viscosity. It has been successfully ap- plied in Shendong Mines and has great value and wide-spread prospective use.展开更多
High performance hydraulic supports have a high requirement in strength,toughness and welding ability of socket mate- rial.Targeting this problem,we analyzed the properties of the high strength socket material 30Cr06,...High performance hydraulic supports have a high requirement in strength,toughness and welding ability of socket mate- rial.Targeting this problem,we analyzed the properties of the high strength socket material 30Cr06,used in high performance hy- draulic supports both at home and abroad and developed a new kind of high strength cast steel 30Cr06A,by making use of an or- thogonal experiment,which provided the design conditions for its optimal composition.The result shows that the strength and toughness of the newly developed high strength cast steel 30Cr06A is much better than that of 30Cr06.Theoretical calculations,mechanical property tests and hardness distribution tests of welded joints were carried out for a study of the welding ability of the new material,which is proved to be very good.Therefore,this 30Cr06A material has been successfully used in the socket of high performance hydraulic support.展开更多
In order to improve production and operation ability of medium and small-sized enterprises, an assessment-index system of production and operation ability was proposed, and a corresponding assessment model was establi...In order to improve production and operation ability of medium and small-sized enterprises, an assessment-index system of production and operation ability was proposed, and a corresponding assessment model was established based on BP neural network. The conjunction weights of the neural network were continuously modified from output layer to input layer in the process of neural network training to reduce the errors between the anticipated and actual outputs. The results from an example show that this method is reliable and feasible. The production and operation abilitv of an enterorise with assessed result of 0.833 is fairly oowerful, and that with assessed result of 0.644 is average.展开更多
Using the self-designed testing system, the seepage tests for cemented broken rocks were conducted, and the impact of different factors on water-resisting ability was analyzed. The results show that(1) seepage process...Using the self-designed testing system, the seepage tests for cemented broken rocks were conducted, and the impact of different factors on water-resisting ability was analyzed. The results show that(1) seepage process of the cemented broken rocks can be divided into two categories: in one category, seepage instability occurs after a period of time, in the other, the permeability decreases slowly and tends to be stable,and seepage instability does not occur;(2) cementing performance of cementing agent and grain size distribution are the decisive factors for water-resisting ability, with the increase of cementing performance and the mass percentage of large grains, the water-resisting ability of the specimen strengthens;(3)aggregate type has little effect on seepage stability, for the specimens with different aggregate types,the permeability and the duration of seepage instability have small difference;(4) initial porosity has a certain effect on the water-resisting ability of the specimen, but has no decisive role. With the increase of the initial porosity, the duration of seepage instability decreases.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.T2325004 and 52161160330)the support from the Hong Kong Institute of Advanced Studies through the materials cluster project。
文摘The glass-forming ability(GFA)of metallic glasses is a key scientific challenge in their development and application,with compositional dependence playing a crucial role.Experimental studies have demonstrated that the addition of specific minor elements can greatly enhance the GFA of parent alloys,yet the underlying mechanism remains unclear.In this study,we use the ZrCuAl system as a model to explore how the addition of minor Al influences the crystallization rate by modulating the properties of the crystal-liquid interface,thereby affecting the GFA.The results reveal that the minor addition of Al significantly reduces the crystal growth rate,a phenomenon not governed by particle density fluctuations at the interface.The impact of minor element additions extends beyond a modest increase in crystal-unfavorable motifs in the bulk supercooled liquid.More importantly,it leads to a significant enrichment of these motifs at the crystal-supercooled liquid interface,forming a dense topological network of crystal-unfavorable structures that effectively prevent the growth of the crystalline interface and enhance GFA.Our results provide valuable insights for the design and development of high-performance metallic glasses.
基金financially supported by National Natural Science Foundation of China (22209133, 22272131, 21972111, 22211540712)Natural Science Foundation of Chongqing (CSTB2022NSCQ-MSX1411)+1 种基金Chongqing Engineering Research Center for Micro-Nano Biomedical Materials and DevicesChongqing Key Laboratory for Advanced Materials and Technologies。
文摘Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn^(2+) deposition reaction and induces phase and structure change of the deposited manganese oxide(Zn_(2)Mn_(3)O_8·H_(2)O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm^(-2) after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn^(2+), and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFB2401703)the National Natural Science Foundation of China(Grant Nos.52177005 and 51871234)the China Postdoctoral Science Foundation(Grant No.2022T150691)。
文摘The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-forming ability and magnetic properties of Fe_(86-x)Y_xB_7C_7(x = 0, 5, 10 at.%) amorphous alloys via both experiments and ab initio molecular dynamics simulations. Furthermore, we explore the correlation between local atomic structures and properties. Our results demonstrate that an increased Y content in the alloys leads to a higher proportion of icosahedral clusters, which can potentially enhance both glass-forming ability and thermal stability. These findings have been experimentally validated. The analysis of the electron energy density and magnetic moment of the alloy reveals that the addition of Y leads to hybridization between Y-4d and Fe-3d orbitals, resulting in a reduction in ferromagnetic coupling between Fe atoms. This subsequently reduces the magnetic moment of Fe atoms as well as the total magnetic moment of the system, which is consistent with experimental results. The results could help understand the relationship between atomic structure and magnetic property,and providing valuable insights for enhancing the performance of metallic glasses in industrial applications.
文摘The aeromechanical st ability for the coupled rotor/fuselage system of helicopters in forward flight i s investigated. The periodic time-varying equations of motion are developed thr ough building a new 24DOF coupled rigid/elastic blended element based on the fle xible multibody system theory in this paper. It accounts for the effects of prec one, sweep, and the moderately large elastic deflections on the blade and elasti city of shaft and fuselage of the helicopter. The dynamic coupling between the r igid motion of blades about the flap, lag and pitch hinges of articulated rotor and moderately large elastic deflections are included. There is no restriction o n the rotation amplitudes of flap, lag and pitch in the formulation. The stabili ty of periodic solution is studied using the Floquet theory. The transition matr ix is calculated by the Newmark integration method. The aeromechanical stability of a new helicopter is studied. The results show that it is stable in the given forward flight. But the instability arises with the decrease of the bending and torsion stiffness of the shaft.
文摘English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment according to our students' practical life in order to improve and enhance their interest in English studying, to encourage them to practice English during their daily life and to cultivate their ability to communicate in English.
文摘Nowadays, the role of listening course is changed and listening teaching begins to gain high priority in foreign language learning and teaching. However, the English level of students in China is still poor, especially in the northwest of Guangxi. One of the reasons is that teachers in senior high schools have a tendency to ignore listening, because they think that listening is time-consumed. They have to finish the teaching scheme punctually, though listening is the basic and important skill among the other three skills, listening teaching gains no large progress.
文摘Based on the literature review of learner autonomy,this paper analyses the necessity and importance of cultivating autonomous listening ability for non-English majors.Then,it presents some practical ways of cultivating autonomous listening ability of non-English majors.
文摘English for Careers is a public course for non-English majors,whose objectives are to develop students’basic language skills for work-related activities:listening,reading,speaking,and writing.As far as the four skills are concerned,most students in higher vocational colleges have the very poor speaking ability.How to improve students’speaking ability is a hard and urgent task for English teachers.This article sets out to analyze the reasons for this problem in English for Careers.Then,based on the second language acquisition and current teaching theory,ways of improving students’speaking ability are suggested.
基金financed by NSC, Metta Education, Grand Hall Company and Auria Solar Company
文摘In this paper we work with the ordinary diffential equation u′′ u3 = 0 and obtain some interesting phenomena concerning blow-up, blow-up rate, life-spann, zeros and critical points of solutions to this equation.
基金the financial support from the Natural Science Foundation of Chongqing(Project NO. CSTC, 2011JJA90020)the Science Foundation for Young Teachers of Logistical Engineering University
文摘Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicated that, compared with petrodiesel, biodiesel was more liable to promote oxidation degradation of diesel oils, leading to worse oxidative stability, detergency and antiwear ability of the oils.
文摘This paper is aimed at studying the effect of reading-based writing instruction on the improvement of senior three students’writing capability.By analyzing students’reading materials from the sample test papers,students are able to notice the distinctive characteristics of the target language ranging from words,expressions,sentence structures and paragraph structures,which is beneficial to students’writing.
文摘The wetting heat and contact angle of sixteen coal samples were determined and the slurry-forming ability of coal were researched. Comparing the relationship of the wetting heat and contact angle with the slurry-forming ability or coal, the auther has found out that the slurry-forming ability of coal can be measured by the wetting heat.
基金financed by NSC,Metta Education,Grand Hall Company and Auria Solar Company
文摘In this paper, we work with the ordinary differential equation n^2u （n）＂ = u（n）^p and obtain some interesting phenomena concerning, boundedness, blow-up, blow-up rate, life-span of solutions to those equations.
基金financially supported by the Swedish Research Link
文摘The miombo woodland is one of the most extensive woodlands in Africa, supporting livelihoods based on biomass fuel for millions of rural people. However, there are growing concerns about the sustainability of harvesting for biomass fuel （mainly charcoal）. Thus, the aim of this study was to examine whether regeneration by coppice is a viable option for sustainably managing miombo woodlands for biomass fuel production. We tested the hypotheses that （1） species, stump diameter, stump height and time since cutting significantly affect the number of sprouts per cut stump （coppice density） and mean sprout height （shoot vigour） and （2） higher coppice density reduces shoot vigour due to competition among coppice shoots in a given stump. In an inventory in areas that were harvested for charcoal production by the local people, 369 stumps of 11 species were recorded with mean coppice stumps ranged from 6 to 84. The mean coppice density ranged from 5 to 8 shoots per stump while the mean height of coppice shoots ranged from 46 to 118 cm with marked interspecific variations. Stump size was signifi- cantly and positively correlated with coppice density for some of the species, but not with shoot vigour for the majority of the species. However, shoot vigour was significantly positively correlated to time since cutting of trees for nearly half of the species. Coppice density had a significant negative correlation with shoot vigour for two species, and a positive correlation for one species. In conclusion, the results provide evidence about the importance of coppice management as a win-win strategy for sustaining charcoal-based rural livelihoods and recovering the miombo woodland ecosystem.
基金the National Natural Science Foundation of China(Grant No.51701071)the Natural Science Foundation of Hunan Province,China(Grant Nos.2018JJ3100 and 2018JJ2078)the Project of the Hunan Educational Department,China(Grant No.19B122)。
文摘The heredity of clusters in rapidly cooled(Zr_(50)Cu_(50))_(100-x)Al_x melts and its correlation with glass-forming ability(GFA)are studied via molecular dynamics simulations.Pair distribution function and the largest standard cluster(LSC)are adopted to characterize the local atomic structures in the(Zr_(50)Cu_(50))_(100-x)Al_(x)systems.The[12/555]icosahedra and their medium-range order(IMRO)play an important role in forming(Zr_(50)Cu_(50))_(100-x)Al_(x)metallic glasses(MGs).The fraction of[12/555],the number of IMRO,and the maximum size of IMRO in MGs increase significantly with increasing x.A tracking study further reveals that the configuration heredity of icosahedral clusters starts from supercooled liquids.No direct correlation exists between the GFA and the onset temperature of continuous or stated heredity.Instead,a larger hereditary supercooled degree of icosahedra matches with better GFA of Al-doped Zr_(50)Cu_(50)alloys.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51671119 and 51871139)the Chongqing Research Program of Basic Research and Frontier Technology,China(Grant No.cstc2018jcyjAX0329 and cstc2018jcyjAX0444)the Key Project of Science and Technology Research Program of Chongqing Education Commission of China(Grant No.KJZD-K201900501).
文摘A small amount of Ni was added into the binary Gd50Co50 amorphous alloy to replace Gd in order to obtain ternary Co50Gd50-xNx(x=1,2,and 3)amorphous alloys.Compared to the binary Gd50Co50 amorphous alloy,the Co50Gd50-xNx amorphous alloys show an enhanced Curie temperature(TC)with a weakened formability.The maximum magnetic entropy change(-Δ^Smpeak)of the Co50Gd50-xNx amorphous alloys is found to decrease with the increasing TC.The adiabatic temperature rise(ΔTad)of the Co50Gd47Ni3 amorphous alloy is superior to that of the Fe-based metallic glasses at room temperature.The variation of the TC and-Δ^Smpeak of the Gd50Co50 amorphous alloy with Ni addition,and the mechanism involved,were discussed.
基金Projects 50274068 Supported by National Natural Science Foundation of China and 20020290001 by Research Fund for Doctoral Program of HigherEducation
文摘To overcome the shortcomings of pouring sands, a thickener with the ability to suspend sands was developed. It is mixed with sands to form densified slurry, and can insure the sands against deposition, jamming pipelines and de- hydration. The chemical structure of the thickener is introduced in this paper and the production process is studied. The main processes include immersion, decomposition, dilution and addition of additives. In order to produce a thickener with high viscosity to suspend sands, key factors must be controlled in each process: the immersion time is 2 h; the mass fraction of formaldehyde is 0.01% and mass of NaCO3 accounts for 15% of dry material; the water temperature is 65 ℃ in summer and 72 ℃ in winter and the decomposition time is 2 h in the reaction; the densified decomposition so- lution should be diluted to 1% mass fraction; the additives of calcium ions and pH indicators must be added to the di- luted liquid; the mass fraction of CaCl2 is 0.048% and the pH value of the solution is 7.5. The thickener is a gel with three-dimensional network structure, a liquid with non-Newtonian behaviour and the characteristics of pseudo-plastic material, a solution with little resistance and the ability to revive its oral primary viscosity. It has been successfully ap- plied in Shendong Mines and has great value and wide-spread prospective use.
文摘High performance hydraulic supports have a high requirement in strength,toughness and welding ability of socket mate- rial.Targeting this problem,we analyzed the properties of the high strength socket material 30Cr06,used in high performance hy- draulic supports both at home and abroad and developed a new kind of high strength cast steel 30Cr06A,by making use of an or- thogonal experiment,which provided the design conditions for its optimal composition.The result shows that the strength and toughness of the newly developed high strength cast steel 30Cr06A is much better than that of 30Cr06.Theoretical calculations,mechanical property tests and hardness distribution tests of welded joints were carried out for a study of the welding ability of the new material,which is proved to be very good.Therefore,this 30Cr06A material has been successfully used in the socket of high performance hydraulic support.
基金Project 2001FJJ036 supported by Society Science Foundation of Henan Province
文摘In order to improve production and operation ability of medium and small-sized enterprises, an assessment-index system of production and operation ability was proposed, and a corresponding assessment model was established based on BP neural network. The conjunction weights of the neural network were continuously modified from output layer to input layer in the process of neural network training to reduce the errors between the anticipated and actual outputs. The results from an example show that this method is reliable and feasible. The production and operation abilitv of an enterorise with assessed result of 0.833 is fairly oowerful, and that with assessed result of 0.644 is average.
基金Financial support for this work,provided by the National Basic Research Program of China(No.2013CB227900)the Ordinary University Graduate Student Research Innovation Project in Jiangsu Province for 2014 of China(KYLX_1370)the National Natural Science Foundation of China(No.51404266),are gratefully acknowledged
文摘Using the self-designed testing system, the seepage tests for cemented broken rocks were conducted, and the impact of different factors on water-resisting ability was analyzed. The results show that(1) seepage process of the cemented broken rocks can be divided into two categories: in one category, seepage instability occurs after a period of time, in the other, the permeability decreases slowly and tends to be stable,and seepage instability does not occur;(2) cementing performance of cementing agent and grain size distribution are the decisive factors for water-resisting ability, with the increase of cementing performance and the mass percentage of large grains, the water-resisting ability of the specimen strengthens;(3)aggregate type has little effect on seepage stability, for the specimens with different aggregate types,the permeability and the duration of seepage instability have small difference;(4) initial porosity has a certain effect on the water-resisting ability of the specimen, but has no decisive role. With the increase of the initial porosity, the duration of seepage instability decreases.
