A novel data mining approach,based on artificial neural network(ANN) using differential evolution(DE) training algorithm,was proposed to model the non-linear relationship between parameters of aging processes and mech...A novel data mining approach,based on artificial neural network(ANN) using differential evolution(DE) training algorithm,was proposed to model the non-linear relationship between parameters of aging processes and mechanical and electrical properties of Cu-15Ni-8Sn-0.4Si alloy.In order to improve predictive accuracy of ANN model,the leave-one-out-cross-validation (LOOCV) technique was adopted to automatically determine the optimal number of neurons of the hidden layer.The forecasting performance of the proposed global optimization algorithm was compared with that of local optimization algorithm.The present calculated results are consistent with the experimental values,which suggests that the proposed evolutionary artificial neural network algorithm is feasible and efficient.Moreover,the experimental results illustrate that the DE training algorithm combined with gradient-based training algorithm achieves better convergence performance and the lowest forecasting errors and is therefore considered to be a promising alternative method to forecast the hardness and electrical conductivity of Cu-15Ni-8Sn-0.4Si alloy.展开更多
By metallographic test, SEM, TEM and energy spectrum, the microstructure and properties of Cu 15Ni 8Sn 0.4Si alloy were studied. The results show that the added Si combines with Ni and forms Ni 3Si and Ni 2Si phases. ...By metallographic test, SEM, TEM and energy spectrum, the microstructure and properties of Cu 15Ni 8Sn 0.4Si alloy were studied. The results show that the added Si combines with Ni and forms Ni 3Si and Ni 2Si phases. During ageing at 380 ℃, the precipitation of Ni 2Si phase suppresses discontinuous precipitation to some degree. After adding Si, the conductivity and hardness of Cu 15Ni 8Sn alloy are increased to some degree.展开更多
采用高温固相法合成Ca取代Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr的Sr3-x Ca x Al0.6Si0.4O4.4F0.6∶Ce3+荧光粉。由于Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr具有十配位Sr(1)和八配位Sr(2),所以激活剂离子Ce3+也具有两个不同的占位。结合Ce3+的光...采用高温固相法合成Ca取代Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr的Sr3-x Ca x Al0.6Si0.4O4.4F0.6∶Ce3+荧光粉。由于Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr具有十配位Sr(1)和八配位Sr(2),所以激活剂离子Ce3+也具有两个不同的占位。结合Ce3+的光谱结果和Van Uitert经验公式,分别研究了十配位Ce(1)3+和八配位Ce(2)3+的猝灭浓度和荧光寿命,指出是由于Ca的掺入减小了Ce(1)3+发光中心,增加了Ce(2)3+发光中心,从而出现随着Ca/Sr比增加,样品在400 nm激发下发光强度减小,而在460 nm激发下发光强度增大的现象。同时,Ca的掺入增强了粉体发光的热稳定性。调节Ca含量可以使粉体实现从绿黄色到黄色的发光,表明Sr3-x Ca x Al0.6Si0.4-O4.4F0.6∶Ce3+荧光粉是一款潜在的适合近紫外和蓝光激发的白光LED用荧光粉。展开更多
Calculation shown that the refraction index of Ge_0.6Si_0.4/Sistrained-layer superlattice n≈3.64, when L_w=9 nm and L_b=24 nm. Analgorithm of numerical iteration for effective refraction index isemployed to obtain di...Calculation shown that the refraction index of Ge_0.6Si_0.4/Sistrained-layer superlattice n≈3.64, when L_w=9 nm and L_b=24 nm. Analgorithm of numerical iteration for effective refraction index isemployed to obtain different effective refraction indexes atdifferent thickness (L). As a result, the thickness ofGe_0.6Si_0.4/Si strained-layer superlattice optical waveguide, L≤363nm, can be determined, which is very important for designingwaveguide devices. An optical waveguide can be made into a nanometerdevice by using Ge_0.6 Si_0.4/Si strained-layer superlattice.展开更多
The synthesis, structure and performance of Li2Mg0.15Mn0.4Co0.45SiO4/C cathode material were studied. The Li2Mg0.15Mn0.4Co0.45SiO4/C solid solution with orthorhombic unit cell （space group Pmn21） was synthesized suc...The synthesis, structure and performance of Li2Mg0.15Mn0.4Co0.45SiO4/C cathode material were studied. The Li2Mg0.15Mn0.4Co0.45SiO4/C solid solution with orthorhombic unit cell （space group Pmn21） was synthesized successfully by combination of wet process and solid-state reaction at high temperature, and its electrochemical performance was investigated primarily. Li2Mg0.15Mn0.4Co0.45SiO4/C composite materials deliver a charge capacity of 302 mA-h/g and a discharge capacity of 171 mA.h/g in the first cycle. The discharge capacity is stabilized at about 100 mA-h/g after 10 cycles at a current density of 10 mA/g in the voltage of 1.5-4.8 V vs Li/Li^＋. The results show that Mg-substitution for the Co ions in Li2Mn0.4Co0.6SiO4 improves the stabilization of initial structure and the electrochemical nerformance.展开更多
A series of CeMn2（Si1-xGex）2（x = 0.2, 0.4, 0.6, 0.8） compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-fie...A series of CeMn2（Si1-xGex）2（x = 0.2, 0.4, 0.6, 0.8） compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-field-cooled（ZFC） and FC magnetization measurements show a transition from antiferromagnetic（AFM） state to ferromagnetic（FM） state at room temperature with the increase of the Ge concentration. For x = 0.4, the sample exhibits two kinds of phase transitions with increasing temperature： from AFM to FM and from FM to paramagnetic（PM） at around TN-197 K and T C-300 K,respectively. The corresponding Arrott curves indicate that the AFM–FM transition is of first-order character and the FM–PM transition is of second-order character. Meanwhile, the coexistence of positive and negative magnetic entropy changes can be observed, which are corresponding to the AFM–FM and FM–PM transitions, respectively.展开更多
The present work is devoted to investigating the microstructure,magnetism and magnetocaloric effects of Si- and Mn-rich FeMn(P,Si) alloys.The Mn-substituted alloys with Fe_(2-x)Mn_xP_(0.4)Si_(0.6)(x=1.25,1.30,1.35,1.4...The present work is devoted to investigating the microstructure,magnetism and magnetocaloric effects of Si- and Mn-rich FeMn(P,Si) alloys.The Mn-substituted alloys with Fe_(2-x)Mn_xP_(0.4)Si_(0.6)(x=1.25,1.30,1.35,1.40,1.45 and 1.50) were prepared by high-energy ball milling and solid-state reaction.Experimental results show that the alloys crystallized into a majority Fe_2P-type hexagonal structure,coexisting with minor amounts of(Mn,Fe)_3Si and(Mn,Fe)_5Si_3 phases.The Curie temperature decreased linearly from 321 to 266 K with increasing Mn content from 1.25 to 1.50 in Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys.The first-order magnetic phase transition became weakened and the second-order magnetic phase transition became dominated with increasing Mn content.Fe_(0.75)Mn_(1.25)P_(0.4)Si_(0.6) alloy presents a maximum isothermal magnetic-entropy changes of 7.2 J(kg K)^(-1) in a magnetic field change of 0-1.5 T.The direct measurement shows that Fe_(0.7)Mn_(1.3)P_(0.4)Si_(0.6) and Fe_(0.65)Mn_(1.35)P_(0.4)Si_(0.6) alloys exhibit a maximum adiabatic temperature change of 1.8 K in a magnetic field change of 0-1.48 T.The thermal hysteresis for all alloys is less than 4 K.These experimental results reveal that Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys could be a candidate material for magnetic refrigeration.展开更多
基金Project(2002AA302505) supported by the Hi-tech Research and Development Program of China
文摘A novel data mining approach,based on artificial neural network(ANN) using differential evolution(DE) training algorithm,was proposed to model the non-linear relationship between parameters of aging processes and mechanical and electrical properties of Cu-15Ni-8Sn-0.4Si alloy.In order to improve predictive accuracy of ANN model,the leave-one-out-cross-validation (LOOCV) technique was adopted to automatically determine the optimal number of neurons of the hidden layer.The forecasting performance of the proposed global optimization algorithm was compared with that of local optimization algorithm.The present calculated results are consistent with the experimental values,which suggests that the proposed evolutionary artificial neural network algorithm is feasible and efficient.Moreover,the experimental results illustrate that the DE training algorithm combined with gradient-based training algorithm achieves better convergence performance and the lowest forecasting errors and is therefore considered to be a promising alternative method to forecast the hardness and electrical conductivity of Cu-15Ni-8Sn-0.4Si alloy.
文摘By metallographic test, SEM, TEM and energy spectrum, the microstructure and properties of Cu 15Ni 8Sn 0.4Si alloy were studied. The results show that the added Si combines with Ni and forms Ni 3Si and Ni 2Si phases. During ageing at 380 ℃, the precipitation of Ni 2Si phase suppresses discontinuous precipitation to some degree. After adding Si, the conductivity and hardness of Cu 15Ni 8Sn alloy are increased to some degree.
文摘采用高温固相法合成Ca取代Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr的Sr3-x Ca x Al0.6Si0.4O4.4F0.6∶Ce3+荧光粉。由于Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr具有十配位Sr(1)和八配位Sr(2),所以激活剂离子Ce3+也具有两个不同的占位。结合Ce3+的光谱结果和Van Uitert经验公式,分别研究了十配位Ce(1)3+和八配位Ce(2)3+的猝灭浓度和荧光寿命,指出是由于Ca的掺入减小了Ce(1)3+发光中心,增加了Ce(2)3+发光中心,从而出现随着Ca/Sr比增加,样品在400 nm激发下发光强度减小,而在460 nm激发下发光强度增大的现象。同时,Ca的掺入增强了粉体发光的热稳定性。调节Ca含量可以使粉体实现从绿黄色到黄色的发光,表明Sr3-x Ca x Al0.6Si0.4-O4.4F0.6∶Ce3+荧光粉是一款潜在的适合近紫外和蓝光激发的白光LED用荧光粉。
文摘Calculation shown that the refraction index of Ge_0.6Si_0.4/Sistrained-layer superlattice n≈3.64, when L_w=9 nm and L_b=24 nm. Analgorithm of numerical iteration for effective refraction index isemployed to obtain different effective refraction indexes atdifferent thickness (L). As a result, the thickness ofGe_0.6Si_0.4/Si strained-layer superlattice optical waveguide, L≤363nm, can be determined, which is very important for designingwaveguide devices. An optical waveguide can be made into a nanometerdevice by using Ge_0.6 Si_0.4/Si strained-layer superlattice.
基金Project(10B054)supported by Scientific Research Fund of Hunan Provincial Education Department,ChinaProjects(2011GK2002,2011FJ3160)supported by the Planned Science and Technology Program of Hunan Province,China
文摘The synthesis, structure and performance of Li2Mg0.15Mn0.4Co0.45SiO4/C cathode material were studied. The Li2Mg0.15Mn0.4Co0.45SiO4/C solid solution with orthorhombic unit cell （space group Pmn21） was synthesized successfully by combination of wet process and solid-state reaction at high temperature, and its electrochemical performance was investigated primarily. Li2Mg0.15Mn0.4Co0.45SiO4/C composite materials deliver a charge capacity of 302 mA-h/g and a discharge capacity of 171 mA.h/g in the first cycle. The discharge capacity is stabilized at about 100 mA-h/g after 10 cycles at a current density of 10 mA/g in the voltage of 1.5-4.8 V vs Li/Li^＋. The results show that Mg-substitution for the Co ions in Li2Mn0.4Co0.6SiO4 improves the stabilization of initial structure and the electrochemical nerformance.
基金Project supported by the Beijing Natural Science Foundation,China(Grant No.2152034)the National Natural Science Foundation of China(Grant Nos.11274357 and 51271196)
文摘A series of CeMn2（Si1-xGex）2（x = 0.2, 0.4, 0.6, 0.8） compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-field-cooled（ZFC） and FC magnetization measurements show a transition from antiferromagnetic（AFM） state to ferromagnetic（FM） state at room temperature with the increase of the Ge concentration. For x = 0.4, the sample exhibits two kinds of phase transitions with increasing temperature： from AFM to FM and from FM to paramagnetic（PM） at around TN-197 K and T C-300 K,respectively. The corresponding Arrott curves indicate that the AFM–FM transition is of first-order character and the FM–PM transition is of second-order character. Meanwhile, the coexistence of positive and negative magnetic entropy changes can be observed, which are corresponding to the AFM–FM and FM–PM transitions, respectively.
基金supported by the National Natural Science Foundation of China(51671045 and 51601073)the Fundamental Research Funds for the Central Universities(DUT16ZD209)+1 种基金the National Magnetic Confinement Fusion Science Program(2013GB107003 and 2015GB105003)the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University(SKLSP201607)
文摘The present work is devoted to investigating the microstructure,magnetism and magnetocaloric effects of Si- and Mn-rich FeMn(P,Si) alloys.The Mn-substituted alloys with Fe_(2-x)Mn_xP_(0.4)Si_(0.6)(x=1.25,1.30,1.35,1.40,1.45 and 1.50) were prepared by high-energy ball milling and solid-state reaction.Experimental results show that the alloys crystallized into a majority Fe_2P-type hexagonal structure,coexisting with minor amounts of(Mn,Fe)_3Si and(Mn,Fe)_5Si_3 phases.The Curie temperature decreased linearly from 321 to 266 K with increasing Mn content from 1.25 to 1.50 in Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys.The first-order magnetic phase transition became weakened and the second-order magnetic phase transition became dominated with increasing Mn content.Fe_(0.75)Mn_(1.25)P_(0.4)Si_(0.6) alloy presents a maximum isothermal magnetic-entropy changes of 7.2 J(kg K)^(-1) in a magnetic field change of 0-1.5 T.The direct measurement shows that Fe_(0.7)Mn_(1.3)P_(0.4)Si_(0.6) and Fe_(0.65)Mn_(1.35)P_(0.4)Si_(0.6) alloys exhibit a maximum adiabatic temperature change of 1.8 K in a magnetic field change of 0-1.48 T.The thermal hysteresis for all alloys is less than 4 K.These experimental results reveal that Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys could be a candidate material for magnetic refrigeration.
