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1.
Deviation values of specific heat difference ACp, the Gibbs free energy difference AG, enthalpy dif- ference AH, and entropy difference AS between the supercooled liquid and corresponding crystalline phase produced by the linear, hyperbolic, and Dubey＇s expres- sions of ACp and the corresponding experimental values are determined for sixteen bulk metallic glasses （BMGs） from the glass transition temperature Tg to the melting temperature Tm. The calculated values produced by the hyperbolic expression for ACp most closely approximate experimental values, indicating that the hyperbolic ACp expression can be considered universally applicable, compared to linear and Dubey＇s expressions for ACp, which are accurate only within a limited range of condi- tions. For instance, Dubey＇s ACp expression provides a good approximation of actual experimental values within certain conditions （i.e., ~ = ACg/AC~ 〈 2, where ACpg and ACp represent the specific heat difference at temperatures Tg and Tm, respectively）. 相似文献
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Machining of micro holes with micro electro- chemical machining （micro ECM） process has been carried out with an indigenously developed set up. This paper describes relevant problems and solutions for the circular micro holes machining process on 304 stainless steel sheets with 60 μm thickness using high speed steel cylindrical tool of diameter 500 ~tm and using dilute I-I2SO4 as elec- trolyte. The taper angle variation of the machined hole is analyzed and reported for different experimental setting parameters. The minimum value of the taper angle of machined holes is achieved at the parameter setting of 0.4 mol/L H2504, 700 kHz, 600 ns and 21 V, for stainless steel sheets and HSS tool. 相似文献
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Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force （Fz） and surface roughness （Ra）. In the present work, the performance of PVD/TiA1N coated carbide inserts was investigated using response surface methodology （RSM） for turning Ti-6A1-4V. The effects of process parameters such as speed （v）, feed （/＇）, depth of cut （d） and back rake angle （Ty） on Fz and Ra were investi- gated. The experimental plan used for four factors and three levels was designed based on face centered, central composite design （CCD）. The experimental results indi- cated that Fz increased with the increase in d, f and decreased with the increase in v and yy, whereas Ra decreased with the increase in v and 7y, and increased with d and v. The goodness of fit of the regression equations and model fits （R2） for Fz and Ra were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model. 相似文献
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Tandem rapid manufacturing of Inconel-625 using laser assisted and plasma transferred arc depositions 总被引：1，自引：0，他引：1
P. Bhargava C．P．Paul C．H．Premsingh S．K．Mishra AtulKumar D．C．Nagpure GurvinderjitSingh L．M．Kukreja 《上海大学学报(英文版)》2013,(4):305-313
This paper presents an investigation on depo- sition of Inconel-625 using laser rapid manufacturing （LRM） and plasma transferred arc （PTA） deposition in individual and tandem mode. LRM has advantages in terms of dimensional accuracy, improved mechanical properties, finer process control, reduced heat input and lower thermal distortion, while PTA scores more in terms of lower initial investment, lower running cost and higher deposition rate. To quantify the clubbed advantages and limitations of both processes, these were studied individually and in tandem. A number of samples were deposited at different process parameters like power, scan speed, powder feed rate. They were subjected to tensile test, adhesion-cohesion test, impact test and micro hardness measurement. The results of individual tests showed the comparable mechanical prop- erties with i20% variation. The mixed dendritic-cellular and dendritic-columnar microstructures were respectively observed for LRM and PTA deposits with a distinct inter- face for the case of tandem deposition. The interface strength of tandem deposits was evaluated employing adhesion-cohesion test, and it was found to be （325 i 35） MPa. The study confirmed the viability of LRM and PTA deposition in tandem for hybrid manufacturing. 相似文献
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Gas metal arc welding （GMAW） develops an arc by controlling the metal from the wire rod and the input pro- cess parameters. The deposited metal forms a weld bead and the mechanical properties depend upon the quality of the weld bead. Proper control of the process parameters which affect the bead geometry, the microstructures of the weldments and the mechanical properties like hardness, is necessary. This experimental study aims at developing mathematical models for bead height （HB）, bead width （WB） and bead penetration （PB） and investigating the effects of four process parameters viz： welding voltage, welding speed, wire feed rate and gas flow rate on bead geometry, hardness and microstructure of AISI321 steel with 10 mm thickness. The transient thermal analysis shows temperature and residual stress distributions at different conduction and convection conditions. 相似文献
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The cellular manufacturing （CM） has been proved as a well-known manufacturing strategy that helps to improve manufacturing efficiency and productivity by utilizing the philosophy of group technology. Large num- ber of papers has been published in the area of design issues of CM system. Unfortunately, the issues related to acceptability of CM in Indian industries are typically not examined rigorously as technical issues. This paper pre- sents the results of a survey carded out to find the status, enabler and barrier of implementing CM system in Indian industries. 相似文献
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The relationship between bilayer nanostructure, defect density and dye-sensitized solar cell （DSCC） per- formances was investigated. By adjusting bilayer nano- structures, defect density of ZnO nanodendrite-nanorods structure was decreased comparing to that of nanoflower- nanorods structure. The performances of DSCC based on ZnO nanodendrites-nanorods structure and nanoflower- nanorods structure were studied by Raman spectrum, room temperature photoluminescence, dye loading, photocurrent density-voltage characteristic and open-circuit voltage decay （OCVD） technique. The device with nanodendrite- nanorods structure has lower charge recombination rate and prolonged electron lifetime due to its microstructure feature. 相似文献
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Min Jiang ;Li-Na Chen ;Jin He ;Guang-Yao Chen ;Chong-He Li ;Xiong-Gang Lu 《上海大学学报(英文版)》2014,(3):265-274
The study of controlled rolling/controlled cooling process parameters which affect the microstructure and mechanical properties of a novel pipeline steel has been optimized by the orthogonal experiment with four factors and three levels in this paper. However, the parameters of thermo-mechanical control process （TMCP） optimized by the Gleeble-3500 hot simulator could not satisfy performance requirements of the X100 pipeline steel. In order to improve the performance of this steel, the influence of finish cooling temperature （FCT） on the microstructure and property is studied in detail. It is found that, as this steel is thermo-mechanically treated by this set of parameters （the start heating temperature, finish rolling temperature （FRT）, FCT and cooling rate of 1,180 ℃, 810 ℃, 350 ℃ and 35 ℃/s, respectively）, the micro- structures are mainly composed of granular bainite （GB） and acicular ferrite （AF）. The effective grain sizes are below 20 μm; the steel reaches the optimal balance between the strength and the toughness; the yield strength is 695 MPa; the tensile strength is 768 MPa; the elongation is 16.6 %; the impact energy is 262 J at room temperature. All indexes could meet the requirements of X100 pipeline steel. 相似文献
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李洁 《温州职业技术学院学报》2002,2(3):32-32,44
应用薄层扫描法测定孩儿茶中消旋儿茶素的含量，方法简便，重现性好，结果准确。在4．0－8．0μg/ml范围内呈线性关系，r=0．9992。回收率为99．6％－102．8％，RSD为1．2％－4．2％。 相似文献
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Magnetic cell sorting and flow cytometry sorting methods for the isolation and function analysis of mouse CD4＋ CD25＋ Treg cells 总被引：5，自引：0，他引：5
Hang Yan Chen-guang Ding Pu-xun Tian Guan-qun Ge Zhan-kui Jin Li-ning Jia Xiao-ming Ding Xiao-ming Pan Wu-jun Xue 《Journal of Zhejiang University. Science. B》2009,10(12):928-932
Objective: In this paper we compared the two methods of cell sorting (magnetic cell sorting and flow cytometry sorting) for the isolation and function analysis of mouse CD4~+ CD25~+ regulatory T (Treg) cells, in order to inform further studies in Treg cell function. Methods: We separately used magnetic cell sorting and flow cytometry sorting to identify CD4~+ CD25~+ Treg cells. After magnetic cell separation, we further used flow cytometry to analyze the purity of CD4~+ CD25~+ Treg cells, trypan blue staining to detect cell viability, and propidium iodide (PI) staining to assess the cell viability. We detected the immune inhibition of CD4~+ CD25~+ Treg cells in the in vitro proliferation experiments. Results: The results showed that compared to flow cytometry sorting, magnetic cell sorting took more time and effort, but fewer live cells were obtained than with flow cytometry sorting. The CD4~+ CD25~+ Treg cells, however, obtained with both methods have similar immunosuppressive capacities. Conclusion: The result suggests that both methods can be used in isolating CD4~+ CD25~+ Treg cells, and one can select the best method according to specific needs and availability of the methodologies. 相似文献
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Mohism as well as Confucianism is a distinguished school in the Spring-Au- tumn and Warring States Periods. But Mozi＇s thought mainly reflects interests and desires of the labor people. He thinks that selfish is the root of social disorder and pain. He puts forward ＂universal loving and multilateral benefiting＂ as a solution. He also contends to build the political centralized monarchy and appoint the good men and able men to office. From the interests and wishes of the producer, Mo Zi critiques the ruler＇s profligate be- havior and Confucian viewpoint of luxuriant burial and long funeral. His standpoint is thrift and simplicity in funerals. 相似文献
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梁霞 《青海师范大学学报(哲学社会科学版)》2013,(6):44-48
中国是茶叶的故乡。茶叶现在已蜚声海内外,与咖啡、可可并称为世界三大饮料。茶叶从种植到饮用,以及形成独特的文化,乃至向海外传播,佛教都作出了杰出的贡献。本文试图通过对佛教茶文化形成过程的历史考察,诠释佛教与茶的内在联系,撂讨佛教对唐宋时期茶叶的种植、名茶研制、饮茶技艺的提升、茶文化的丰富、茶道精神的萌芽,以及茶文化的对外传播方面所作的重要贡献,以期明晰佛教在中国茶文化史上的影响和地位。 相似文献
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利用方波伏安法研究了尿酸在聚甘氨酸修饰玻碳电极上的电化学氧化行为.结果表明:在0.01 mol/L磷酸盐缓冲液(pH=7)中,尿酸在+0.31 mv左右产生一个氧化峰,峰电流与尿酸在1.0×10-6—1.0×10-5mol/L浓度范围呈较好的线性关系,相关系数为0.9945.该方法可用于直接测定人体尿酸,回收率为95.5%-104.1%,相对标准偏差为1.4%. 相似文献
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对黄柏黄色素的提取及稳定性进行了研究,结果表明:黄柏黄色素的最大吸收波长λm ax=335 nm,最适宜的提取剂为乙醇,最佳的提取条件为:提取剂浓度为60%,提取剂pH值为3~7,提取温度为60℃.该色素耐光、耐热性强,常用的食品添加剂以及金属离子Na+、Cu2+、Mg2+、Ca2+等对色素无明显影响. 相似文献
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游文玲 《宁德师专学报(自然科学版)》2009,21(3):310-312,327
新课程的改革过程不仅应关注课堂上教师的教学行为和学生学习行为,而且还应关注数学课外作业的设计、布置、批改、辅导等,使学生在作业的过程中体验快乐,培养能力,学会合作,同时还有利于融洽师生感情,强化学习动机．结合实践从高中数学正确的作业观,作业的优化设计,作业批改评语等方面简要阐述． 相似文献
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陈少华 《中国科教创新导刊》2009,(12):138-138
本文通过数控教学实践研究,运用现代教育技术改革传统的教学方法、手段和教学模式,融理论教学与实验教学为一体,激发学生的学习兴趣,调动学生的学习积极性。使学生对所学的内容充分感知,在直接经验与抽象经验之间架设一座“桥梁”,培养学生的实际应用能力,提高了教学质量。 相似文献
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