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Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University
Solid State Communications | Year: 2014

The LaFe11.6Si1.4 compounds are annealed at 1503 K for 5 h and cooled down to room temperature by furnace cooling, air cooling, and quenching in ice water, respectively. The main phase is 1:13 phase in those compounds. The impurity phase is α-Fe, and the amount of LaFeSi phase is so small that it is hard to be observed in their XRD patterns. 1:13 phase has a precipitation reaction at 1308 K during cooling process and produces LaFeSi phase. But the cooling rate in the high temperature range is very high and the time kept at about 1308 K is very short, also the amount of LaFeSi phase reformed during cooling process is very small. It results in there being almost no difference in XRD patterns and SEM micrographs of LaFe11.6Si 1.4 compounds annealed at 1503 K (5 h) and followed by furnace cooling, air cooling, and quenching in ice water to room temperature respectively. For studying the influence of different cooling processes on magnetic property, the TC, thermal and magnetic hysteresis, magnetocaloric effect, and relative cooling power of those compounds are investigated. The result shows that the maximum ΔSM (T, H) and RCP of LaFe11.6Si1.4 prepared by furnace cooling is not smaller than the other two alloys under the field of 0-2 T. © 2014 Published by Elsevier Ltd.


Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University
Journal of Alloys and Compounds | Year: 2011

The LaFe11.6Si1.4 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K(5 h) to 1623 K(2 h). The powder X-ray diffraction and metallographic microscopy show that 1423 K and 1523 K are two curial temperatures, at which large amount of 1:13 phase begins to form and the most amount of 1:13 phase is obtained, respectively. With annealing temperature increasing to 1573 K and 1623 K, a new phase of La5Si3 is detected in LaFe11.6Si 1.4 compound. According to the DSC curve of as-cast LaFe 11.6Si1.4 compound and the X-ray patterns of annealed LaFe11.6Si1.4 compounds, the high-temperature phase transition process is analyzed. For studying the influence of different high-temperature and short-time annealing on the Curie temperature, thermal and magnetic hysteresis, magnetocaloric effect of LaFe11.6Si 1.4 compound annealed at different temperatures are also investigated. © 2011 Elsevier B.V. All rights reserved.


Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University
Journal of Magnetism and Magnetic Materials | Year: 2011

The phase relation of LaFe11.5Si1.5 alloys annealed at different high-temperature from 1223 K (5 h) to 1673 K (0.5 h) has been studied. The powder X-ray diffraction (XRD) patterns show that large amount of 1:13 phase begins to form in the matrix alloy consisting of αFe and LaFeSi phases when the annealing temperature is 1423 K. In the temperature range from 1423 to 1523 K, αFe and LaFeSi phases rapidly decrease to form 1:13 phase, and LaFeSi phase is rarely observed in the XRD pattern of LaFe 11.5Si1.5 alloy annealed at 1523 K. With annealing temperature increasing from 1573 to 1673 K, the LaFeSi phase is detected again in the LaFe11.5Si1.5 alloy, and there is La 5Si3 phase when the annealing temperature reaches 1673 K. There almost is no change in the XRD patterns of LaFe11.5Si 1.5 alloys annealed at 1523 K for 35 h. According to this result, the La0.8Ce0.2Fe11.5-xCoxSi 1.5 (0≤×≤0.7) alloys are annealed at 1523 K (3 h). The analysis of XRD patterns shows that La0.8Ce0.2Fe 11.5xCoxSi1.5 alloys consist of the NaZn 13-type main phase and αFe impurity phase. With the increase of Co content from x=0 to 0.7, the Curie temperature TC increases from 180 to 266 K. Because the increase of Co content can weaken the itinerant electron metamagnetic transition, the order of the magnetic transition at T C changes from first to second-order between x=0.3 and 0.5. Although the magnetic entropy change decreases from 34.9 to 6.8 J/kg K with increasing Co concentration at a low magnetic field of 02 T, the thermal and magnetic hysteresis loss reduces remarkably, which is very important for the magnetic refrigerant near room temperature. © 2011 Elsevier B.V. All rights reserved.


Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University
Acta Metallurgica Sinica (English Letters) | Year: 2011

The LaFe 11:4Si 1:6 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K (5 h) to 1623 K (2 h). The powder X-ray diffraction (XRD) and microstructure observations show that large amount of 1:13 phase begins to appear in the LaFe 11:4Si 1:6 compound annealed at 1423 K (5 h). In the temperature range from 1423 K to 1523 K, the α-Fe and LaFeSi phases rapidly decrease to form 1:13 phase. The LaFeSi phase is rarely observed by XRD when the as-cast compound is annealed at 1523 K (5 h). With annealing temperature in-creasing to 1573 K, LaFeSi phase is detected again in LaFe11:4Si1:6 compound. In LaFe 11:4Si 1:6 compounds annealed at 1523 K (5 h), at 1373 K (2 h)+1523 K (5 h), and 1523 K (7 h)+1373 K (2 h), the impurity phases including small amount of α-Fe and LaFeSi phase reduce in turn. The magnetic measurement shows that LaFe11:4Si1:6 compounds annealed by above three processes keep the first-order of magnetic transition behavior, and T C are both at about 200 K. But the values of the maximal ΔSM(T;H) of has large difference, they are 9.94, 12.66, and 13.96 J/(kg · K) under a magnetic field of 0-2 T, respectively.


Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University | Xiao D.,Sichuan University
Journal of Magnetism and Magnetic Materials | Year: 2014

The effects of Co on the formation of NaZn13-type phase in as-cast and annealed LaFe16-xCoxSi1.4 and LaFe11.6Si1.4-xCox alloys have been investigated systematically by XRD, SEM, and EDS, respectively. In LaFe 11.6Si1.4-xCox alloys, the introduction of Co will hamper the formation of 1:13 and LaFeSi phases, and help the formation of αof (Co, Si) solid solution, so there is almost only α-Fe(Co, Si) solid solution when x reaches 0.7 in as-cast and annealed LaFe 11.6Si1.4-xCox alloys. Although the amounts of 1:13 phase increases when x reaches 0.7 in as-cast LaFe16-xCo xSi1.4 alloys, there is a small amount of α-Fe in LaFe11.6-xCoxSi1.4 alloys annealed at 1523 K (5 h), which indicates that the annealing time for obtaining a 1:13 single-phase cannot be shortened in our high-temperature and short-time annealing. The studies on the magnetic properties show that the Curie temperature TC goes up from 207 K to 285 K with increase of Co content from x=0.1 to 0.8. The introduction of Co element weakens the first order magnetic phase transition, which results in the change of magnetic transition type from first to second order at about x=0.3-0.5. At the same time, it has effects on the phase transition temperature interval and magnetic filed interval, and the changing rate of magnetic entropy change dependence on the Co content in LaFe 16-xCoxSi1.4 alloys. The maximum entropy values of LaFe11.6-xCoxSi1.4 alloys decrease with the increase of Co content, but the relative cooling power does not decrease, the reason of which is that the phase transition temperature interval increases and the first order phase transition character decreases, and the effective refrigeration temperature range becomes big, which is useful to the application of magnetic refrigeration material. © 2014 Elsevier B.V.


Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University
Journal of Alloys and Compounds | Year: 2011

The phase relation, microstructural, hysteresis, Curie temperature, and magnetocaloric effects of LaFe11.6Si1.4Bx (x = 0.1, 0.2, 0.3, 0.4, and 0.5) prepared by arc-melting and then annealed at 1373 K (1.5 h) + 1523 K (5 h) were investigated. It was found that the main phase is NaZn13-type phase, the impurity phases include α-Fe, Fe 2B, and small amount of La5Si3. The boron atom can dissolve into the crystal lattice of LaFe11.6Si 1.4Bx to form interstitial solid solution, but the content of solid solution is not up to x = 0.5. For LaFe11.6Si 1.4Bx (x = 0.1, 0.3, and 0.5) compounds, the Curie temperature TC increases from 190.6 to 198.3 K with the increasing of B content from x = 0.1 to 0.5. The first order magnetic transition behavior becomes weaker and magnetic entropy change ΔSM (T, H) drops with the increasing of B content, respectively. However, ΔSM (T, H) still remains a large value, 11.18 J/kg K, when x reaches to 0.5 at 0-2 T. An attractive feature is that both thermal and magnetic hysteresis can be reduced remarkably by introducing B. The maximum magnetic hysteresis loss near TC drops from 22.52 to 4.95 J/kg when the content of B increases from x = 0.1 to 0.5. © 2010 Elsevier B.V. All rights reserved.


Chen X.,Sichuan University | Chen X.,Neijiang Teachers College | Chen Y.,Sichuan University | Tang Y.,Sichuan University
Journal of Alloys and Compounds | Year: 2011

The phase relation, microstructure, Curie temperatures (TC), magnetic transition, and magnetocaloric effect of (Gd1-xEr x)5Si1.7Ge2.3 (x = 0, 0.05, 0.1, 0.15, and 0.2) compounds prepared by arc-melting and then annealing at 1523 K (3 h) using purity Gd (99.9 wt.%) are investigated. The results of XRD patterns and SEM show that the main phases in those samples are mono-clinic Gd 5Si2Ge2 type structure. With increase of Er content from x = 0 to 0.2, the values of magnetic transition temperatures (TC) decrease linearly from 228.7 K to 135.3 K. But the (Gd 1-xErx)5Si1.7Ge2.3 compounds display large magnetic entropy near their transition temperatures in a magnetic field of 0-2 T. The maximum magnetic entropy change in (Gd 1-xErx)5Si1.7Ge2.3 compounds are 24.56, 14.56, 16.84, 14.20, and 13.22 J/kg K-1 with x = 0, 0.05, 0.1, 0.15, and 0.2, respectively. © 2011 Elsevier B.V. All rights reserved.


Hu Q.G.,Neijiang Teachers College
Advanced Materials Research | Year: 2014

Firstly, the traditional MIPv6 protocol is analyzed. Secondly, the point-to-point MIPv6 protocol is put forward to solve the key question of the mobile IP technology. Then, it is introduced how the new protocol works. After that, the performance of the new protocol is simulated with OPNET software, whose result shows the performance of the new protocol is better than that of the traditional protocol. © (2014) Trans Tech Publications, Switzerland.


Tang N.,Neijiang Teachers College
World Transactions on Engineering and Technology Education | Year: 2016

In view of the traditional educational orientation towards disciplinary knowledge with weaknesses in innovation, practice and teamwork, software engineering personnel training based on CDIO (Conceive, Design, Implement, Operate) was implemented for the software engineering major of the Department of Computer Science at Neijiang Teachers College in Sichuan, China. The reform of the curriculum, teaching, practice environment, and guarantee and assessment systems are described in detail, to provide a reference for engineering education of the software engineering discipline. © 2016 WIETE.


Hu Q.-G.,Neijiang Teachers College
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

For mobile IPv6, home agent (HA) plays an important role. Each mobile node (MN) has a home IP address, it will be not changeable. Also, the home agent (HA) of MN is not changeable. This rule provides the convenient for the ongoing communication without interruption. But it has some obvious drawbacks. Here, the new variable HA scheme is proposed. Every MN has a dynamic cache table, recording the information such as its home address, care-of address, and history address etc. If the accumulated time in one region exceeds that in the hometown, the foreign agent (FA) could become home agent (HA), the home agent could become history agent. Later, the performance of the new protocol is simulated with OPNET software, whose result shows the performance of the new protocol works better than that of the traditional protocol. © 2015 SPIE.

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