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复方热参二号片治疗慢性气管炎临床疗效观察
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《人民军医》 1974年第7期58-60,共3页
遵照伟大领袖毛主席关于'中国医药学是一个伟大的宝库,应当努力发掘,加以提高'的教导,1972年冬季我们曾对河南南部山区民间治疗咳喘的一种草药——热参(又名华山参、山烟,学名Physochlaina infundibularis Kuang,茄科泡囊草属)... 遵照伟大领袖毛主席关于'中国医药学是一个伟大的宝库,应当努力发掘,加以提高'的教导,1972年冬季我们曾对河南南部山区民间治疗咳喘的一种草药——热参(又名华山参、山烟,学名Physochlaina infundibularis Kuang,茄科泡囊草属)进行临床验证,在单味药有效的基础上,又组成了复方热参片进行治疗。用复方热参片共治疗82例,四个疗程,近控38例,显效32例,好转11例,显效以上85.4%,有效率98.8%。为了扩大验证。 展开更多
关键词 热参 疗效 慢性气管炎 华山 祛寒药 临床疗效观察
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轻钢承重墙用硅酸钙板热工参数模型及墙体耐火极限变参数模拟研究 被引量:3
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作者 尹亮 叶继红 +1 位作者 倪照鹏 邱培芳 《消防科学与技术》 CAS 北大核心 2015年第10期1342-1351,1358,共11页
根据冷成型钢承重组合墙墙体足尺耐火试验及墙用硅酸钙板内部粉末热工参数测试结果,利用ANSYS软件,对立柱控制截面建立传热模型。通过对比耐火试验结果,给出了硅酸钙板的热工参数模型。通过参数分析发现,改变C型龙骨规格、拼接方式对耐... 根据冷成型钢承重组合墙墙体足尺耐火试验及墙用硅酸钙板内部粉末热工参数测试结果,利用ANSYS软件,对立柱控制截面建立传热模型。通过对比耐火试验结果,给出了硅酸钙板的热工参数模型。通过参数分析发现,改变C型龙骨规格、拼接方式对耐火极限没有显著影响;改变墙板厚度及火源模型则有显著影响。提出了单侧受火双拼C型龙骨墙体内龙骨截面温度分布模型,分析了火源模型降温段引起的墙体截面不同位置降温滞后现象。 展开更多
关键词 冷成型钢承重墙 硅酸钙板 数值模拟 耐火极限
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自拟参柏清热方坐浴对低位单纯性肛瘘患者术后创面修复的影响 被引量:4
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作者 李辉 《齐齐哈尔医学院学报》 2022年第2期157-160,共4页
目的研究自拟参柏清热方坐浴对低位单纯性肛瘘患者术后创面修复的影响。方法选取2019年1—12月本院收治的低位单纯性肛瘘患者84例作为研究对象,随机分为研究组和对照组,每组各42例。对照组行常规治疗,研究组在对照组基础上采用自拟参柏... 目的研究自拟参柏清热方坐浴对低位单纯性肛瘘患者术后创面修复的影响。方法选取2019年1—12月本院收治的低位单纯性肛瘘患者84例作为研究对象,随机分为研究组和对照组,每组各42例。对照组行常规治疗,研究组在对照组基础上采用自拟参柏清热方坐浴。比较两组治疗14 d后疗效,比较两组治疗前及治疗7 d、14 d后创面面积、创面愈合情况(创面渗液、创面肿胀),比较治疗前及治疗14 d后斯钙素2(STC2)、疾病相关因子[表皮细胞生长因子(EGF)、碱性成纤维细胞生长因子(bFGF)、血清淀粉蛋白A(SAA)]水平。结果治疗前两组创面面积比较,差异无统计学意义(P>0.05);治疗14 d后,两组治疗有效率比较,差异无统计学意义(P>0.05);治疗7 d、14 d后,研究组创面面积、创面渗液、创面肿胀评分水平均明显低于对照组,差异有统计学意义(P<0.05);治疗14 d后,STC2、SAA水平明显低于治疗前及同期对照组,研究组EGF、bFGF水平明显高于治疗前及同期对照组,差异均有统计学意义(P<0.05)。结论自拟参柏清热方坐浴能够明显改善低位单纯性肛瘘患者术后创面修复程度,降低创面渗液和肿胀程度。 展开更多
关键词 自拟柏清 坐浴 低位单纯性肛瘘 创面修复
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十二、补益药——(一)补气药 华山参
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作者 滕崇德 李继瓒 +1 位作者 杨懋琛 钱玉华 《山西医药杂志》 CAS 1976年第S1期71-72,共2页
我省中草药自然资源比较丰富。无产阶级文化大革命以来,广大工农兵和医药卫生工作者,狠批了刘少奇、林彪邓小平的反革命修正主义卫生路线。在毛主席革命路线指引下,一个大搞中草药的群众运动正在深入展开。遵照毛主席关于"把医疗... 我省中草药自然资源比较丰富。无产阶级文化大革命以来,广大工农兵和医药卫生工作者,狠批了刘少奇、林彪邓小平的反革命修正主义卫生路线。在毛主席革命路线指引下,一个大搞中草药的群众运动正在深入展开。遵照毛主席关于"把医疗卫生工作的重点放到农村去"的伟大教导,山西大学生物系的同志们,在广大工农兵、基层医务人员协助下,在开门办学的过程中,通过调查访问,开座谈会及举办中草药短期训练班等多种形式,收集了我省所产部分中草药及其单验方,参考有关文献资料,撰写成文。山西省中医研究所、山西省西医离职学习中医班、山西省药品检验所、山西医学院的同志们协助审稿。这里共选编的165种中草药(其中植物药150种,动物药15种,并附土单验方500余个。)在《山西中草药》中没有选编。供"赤脚医生"及广大基层医药卫生人员在自种、自采、自制、自用中草药工作中参考。 展开更多
关键词 华山 中草药 热参 祛寒药 单验方 本品
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等参三角形热夹杂的构造及位移场数值计算
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作者 龚诗雨 朱凯 +4 位作者 陈楠 蒋志桢 刘宽宇 李璞 金晓清 《固体力学学报》 CAS CSCD 北大核心 2023年第2期133-143,共11页
在材料制备和机械设计中,局部温升是造成材料失效和故障形成的重要因素之一.依照微观力学中,采用热夹杂模型可以定量深入地揭示与局部温升所关联的力学机理.在过往的研究中,受均匀热本征应变的夹杂模型广受关注;而相关非均匀分布的热本... 在材料制备和机械设计中,局部温升是造成材料失效和故障形成的重要因素之一.依照微观力学中,采用热夹杂模型可以定量深入地揭示与局部温升所关联的力学机理.在过往的研究中,受均匀热本征应变的夹杂模型广受关注;而相关非均匀分布的热本征应变问题,因其理论推导复杂而研究不多.论文首先给出在平面无限域中,受线性分布热本征应变作用的多边形夹杂的位移场解析解.基于格林函数法和围道积分,推导边界线单元的位移响应封闭解,该解通过叠加可直接给出线性热本征应变作用下的任意多边形夹杂的解析表达式.受到有限元分析中等参单元思想的启发,论文进一步将这种“等参元”方法扩展至求解Eshelby夹杂问题中.在该研究中,三角形单元的本征应变插值公式与位置坐标变换式均使用了相同的形函数与节点参数,因而所构建的单元模型称为等参三角形夹杂模型.论文方法可便捷地用于处理受任何分布热本征应变的任意形状二维Eshelby夹杂问题.相较于传统的有限元分析,论文所构建的数值求解方案实施方便且优势明显:只需在夹杂域上进行三角形网格剖分、而无需在无限的基体域上划分网格,因而可以极大地提高前处理便捷性及计算效率.此外,论文所给出的多边形夹杂解析解,不仅可以更准确地探究微结构附近的热物理机理,还可以有效地规避有限元在夹杂界面和边界犄角附近的致密网格划分,从而节省了大量计算机内存及成本消耗.所给出的算例验证表明,即使对于复杂的热本征应变问题,本算法仍具有良好的精度和可靠性. 展开更多
关键词 三角形夹杂 任意形状Eshelby夹杂 非均匀本征应变 格林函数 封闭解析解
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Prediction of mechanical properties of A357 alloy using artificial neural network 被引量:7
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作者 杨夏炜 朱景川 +4 位作者 农智升 何东 来忠红 刘颖 刘法伟 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第3期788-795,共8页
The workpieces of A357 alloy were routinely heat treated to the T6 state in order to gain an adequate mechanical property.The mechanical properties of these workpieces depend mainly on solid-solution temperature,solid... The workpieces of A357 alloy were routinely heat treated to the T6 state in order to gain an adequate mechanical property.The mechanical properties of these workpieces depend mainly on solid-solution temperature,solid-solution time,artificial aging temperature and artificial aging time.An artificial neural network(ANN) model with a back-propagation(BP) algorithm was used to predict mechanical properties of A357 alloy,and the effects of heat treatment processes on mechanical behavior of this alloy were studied.The results show that this BP model is able to predict the mechanical properties with a high accuracy.This model was used to reflect the influence of heat treatments on the mechanical properties of A357 alloy.Isograms of ultimate tensile strength and elongation were drawn in the same picture,which are very helpful to understand the relationship among aging parameters,ultimate tensile strength and elongation. 展开更多
关键词 A357 alloy mechanical properties artificial neural network heat treatment parameters
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Effect of hot deformation conditions on grain structure and properties of 7085 aluminum alloy 被引量:12
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作者 陈送义 陈康华 +1 位作者 贾乐 彭国胜 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第2期329-334,共6页
The influences of deformation conditions on grain structure and properties of 7085 aluminum alloy were investigated by optical microscopy and transmission electron microscopy in combination with tensile and fracture t... The influences of deformation conditions on grain structure and properties of 7085 aluminum alloy were investigated by optical microscopy and transmission electron microscopy in combination with tensile and fracture toughness tests. The results show that the volume fraction of dynamic recrystallization increased with the decrease of Zener-Hollomon (Z) parameter, and the volume fraction of static recrystallization increased with the increasing of Z parameter. The strength and fracture toughness of the alloy after solution and aging treatment first increased and then decreased with the increase of Z parameter. The microstructure map was established on the basis of microstructure evolution during deformation and solution heat treatment. The optimization deformation conditions were acquired under Z parameters of 1.2×10^10-9.1×10^12. 展开更多
关键词 7085 aluminum alloy Zener-Hollomon parameter hot deformation grain structure dynamic recrystallization static recrystallization
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Effect of cooling rate on solidification parameters and microstructure of A1-7Si-0.3Mg-0.15Fe alloy 被引量:8
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作者 陈瑞 石玉峰 +1 位作者 许庆彦 柳百成 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第6期1645-1652,共8页
The effects of cooling rate on the solidification parameters and microstructure of Al-7Si-0.3Mg-0.15 Fe alloy during solidification process were studied.To obtain different cooling rates,the step casting with five dif... The effects of cooling rate on the solidification parameters and microstructure of Al-7Si-0.3Mg-0.15 Fe alloy during solidification process were studied.To obtain different cooling rates,the step casting with five different thicknesses was used and the cooling rates and solidification parameters were determined by computer-aided thermal analysis method.The results show that at higher cooling rates,the primary α(Al) dendrite nucleation temperature,eutectic reaction temperature and solidus temperature shift to lower temperatures.Besides,with increasing cooling rate from 0.19 ℃/s up to 6.25 ℃/s,the secondary dendritic arm spacing decreases from 68 μm to 20 μm,and the primary dendritic volume fraction declines by approximately 5%.In addition,it reduces the length of Fe-bearing phase from 28 μm to 18 μm with a better uniform distribution.It is also found that high cooling rates make for modifying eutectic silicon into fibrous branched morphology,and decreasing block or lamella shape eutectic silicon. 展开更多
关键词 aluminium alloys cooling rate thermal analysis solidification parameters MICROSTRUCTURE
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Hot deformation behavior of extruded AZ80 magnesium alloy 被引量:12
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作者 李慧中 卫晓燕 +2 位作者 欧阳杰 姜俊 李轶 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第11期3180-3185,共6页
The hot deformation behavior of extruded AZ80 magnesium alloy was studied through hot compression tests performed at temperatures ranging from 250 to 450 ~C with strain rates varying from 0.001 to 10 s-1. The flow str... The hot deformation behavior of extruded AZ80 magnesium alloy was studied through hot compression tests performed at temperatures ranging from 250 to 450 ~C with strain rates varying from 0.001 to 10 s-1. The flow stress was corrected due to the deformation heating. The Zener-Hollomon parameter (Z parameter) and processing map were established to describe the hot deformation behavior. The results indicate that the applicable deformation should be conducted at the strain rate of 0.1 s-~ and the temperature range of 350-400 ~C. Besides, the relationship between the microstructure evolution and Z parameter was also discussed. High temperature and low strain rate result in a low Z parameter, which leads to full dynamic recrystallization (DRX) and large DRX grain size in the microstructure. Considering processing map and microstructure, the hot deformation should be carried out at the temperature of 400 ~C and the strain rate of 0.1 s 1. 展开更多
关键词 AZ80 magnesium alloys hot deformation processing map Z parameter
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Influence of drawing process parameters on forming of micro copper tube with straight grooves 被引量:4
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作者 汤勇 欧栋生 +2 位作者 万珍平 陆龙生 练彬 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第10期2264-2269,共6页
Using high-speed oil-filled spinning method,high quality micro copper tube with straight grooves(MCTSG) with an outer diameter of 6 mm was obtained.Then,MCTSG with an outer diameter of 3-6 mm was fabricated successf... Using high-speed oil-filled spinning method,high quality micro copper tube with straight grooves(MCTSG) with an outer diameter of 6 mm was obtained.Then,MCTSG with an outer diameter of 3-6 mm was fabricated successfully by multi-pass drawing processing method.The influence of drawing parameters on the forming of micro straight grooves was investigated based on the forming mechanism.The results show that the values of groove depth and width decrease,while the wall thickness increases as the drawing diameter decreases.At the same time,the groove depth and width increase,while the wall thickness decreases as the die angle increases.The drawing force increases as the reduction increases.Excessive copper tube reduction may results in groove folding and segmental teeth.The drawing force decreases firstly and then increases with the increases in die angle.When the die angle α is 16°,the drawing force is the smallest,indicating 16° is the optimal angle. 展开更多
关键词 micro-groove DRAWING drawing parameter drawing force heat pipe
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Self-heating tendency evaluation of sulfide ores based on nonlinear multi-parameters fusion 被引量:1
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作者 潘伟 吴超 +1 位作者 李孜军 杨月平 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期582-589,共8页
In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials ... In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials and their self-heating characteristics were measured in laboratory. Furthermore, the measured temperature was studied by integrating wavelet transform, nonlinear characteristic parameters extraction and fuzzy comprehensive evaluation. The results indicate that only the ore samples 1, 2, 6 and 9 have obvious self-heating phenomenon, and their self-heating initiative temperatures are 220 ℃, 239 ℃, 220 ℃ and 220 ℃, respectively, which means that they are difficult to produce self-heating under normal mining conditions. The correlation dimension of self-heating process is fraction and the maximum Lyapunov exponent is positive, which means that it is feasible to study the self-heating process based on chaotic dynamics theory. The nonlinearities of self-heating process of these four samples (ore samples 1, 2, 6 and 9) are 0.8227, 0.7521, 0.9401 and 0.8827 respectively and the order of the samples according to these results is: sample 6, sample 9, sample 1, sample 2, which is consistent with the measured results of self-heating characteristics. Therefore, the nonlinearity method can be used to evaluate the self-heating tendency of sulfide ores, and it is an effective verification of the reliability of measured results. 展开更多
关键词 sulfide ores self-heating process nonlinear characteristic parameter NONLINEARITY self-heating tendency
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Integrated power electronics module based on chip scale packaged power devices 被引量:2
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作者 王建冈 阮新波 《Journal of Southeast University(English Edition)》 EI CAS 2009年第3期367-371,共5页
High performance can be obtained for the integrated power electronics module(IPEM) by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM (HB-... High performance can be obtained for the integrated power electronics module(IPEM) by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM (HB-IPEM), consisting of two chip scale packaged MOSFETs and the corresponding gate driver and protection circuits, is fabricated at the laboratory. The reliability of the IPEM is controlled from the shape design of solder joints and the control of assembly process parameters. The parasitic parameters are extracted using Agilent 4395A impedance analyzer for building the parasitic parameter model of the HB- IPEM. A 12 V/3 A output synchronous rectifier Buck converter using the HB-IPEM is built to test the electrical performance of the HB-IPEM. Low voltage spikes on two MOSFETs illustrate that the three-dimensional package of the HB-IPEM can decrease parasitic inductance. Temperature distribution simulation results of the HB-IPEM using FLOTHERM are given. Heat dissipation of the solder joints makes the peak junction temperature of the chip drop obviously. The package realizes three-dimensional heat dissipation and has better thermal management. 展开更多
关键词 integrated power electronics module chip scale package RELIABILITY parasitic parameter thermal management
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High temperature deformation behavior and optimization of hot compression process parameters in TC11 titanium alloy with coarse lamellar original microstructure 被引量:4
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作者 鲁世强 李鑫 +2 位作者 王克鲁 董显娟 傅铭旺 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第2期353-360,共8页
The high temperature deformation behaviors of α+β type titanium alloy TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) with coarse lamellar starting microstructure were investigated based on the hot compression tests in the tem... The high temperature deformation behaviors of α+β type titanium alloy TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a+fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α+β phase field. The peak of efficiency of power dissipation in α+β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α+β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a+β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results. 展开更多
关键词 titanium alloy coarse lamellar microstructure high temperature deformation behavior processing map hot compression process parameter optimization
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Thermodynamics Properties of Oxymatrine in NaCl Solution
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作者 李宗孝 蒲小华 +1 位作者 赵微微 陈艳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第1期121-124,I0004,共5页
The enthalpies of dissolution of oxymatrine in 0.9%NaCl solution were measured using a RD496-2000 Calvet Microcalorimeter at 309.65 K under atmospheric pressure. The differen tial enthalpy and molar enthalpy of oxymat... The enthalpies of dissolution of oxymatrine in 0.9%NaCl solution were measured using a RD496-2000 Calvet Microcalorimeter at 309.65 K under atmospheric pressure. The differen tial enthalpy and molar enthalpy of oxymatrine dissolution in the 0.9%NaCl solution of were determined. The corresponding kinetic equation that described the dissolution process was elucidated. Moreover, the half-life, molar entropy, molar enthaply, and Gibbs free energy of the dissolution process were also obtained. 展开更多
关键词 OXYMATRINE THERMODYNAMIC KINETICS 0.9%NaCl solution
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Effect of Heat Stress on Photosynthetic Characteristics of Different Green Organs of Winter Wheat During Grain-filling Stage 被引量:28
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作者 徐晓玲 王志敏 张俊平 《Acta Botanica Sinica》 CSCD 2001年第6期571-577,共7页
Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag le... Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag leaf blade, nag leaf sheath, peduncle, glume, lemma and awn during grain-filling stage. The results showed that heat acclimation during grain-filling stage increased thermotolerance of wheat with significant differences among different green organs. During heat stress, the decreases of the efficiency of primary light energy conversion (F-v/F-m) of PS II and pigment (chlorophyll and carotenoid) content were much slower in peduncle, flag leaf sheath and glume than in nag leaf blade, lemma and ann; and the percentage of decrease in net photosynthetic rate (P-n) of ear was lower than that of the nag leaf blade. The measured photosynthetic parameters (F-v/F-m, P-n and pigment content) of 'JD 8', a relatively heat tolerant variety, declined more slowly than those of the other three varieties during the whole heat stress period. 展开更多
关键词 winter wheat net photosynthetic rate chlorophyll fluorescence kinetics parameters heat tolerance
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Grain refinement of Mg-Al alloys by optimization of process parameters based on three-dimensional finite element modeling of roll casting 被引量:2
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作者 胡红军 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第3期773-780,共8页
To study the influence of roll casting process parameters on temperature and thermal-stress fields for the AZ31 magnesium alloy sheets,three-dimensional geometric and 3D finite element models for roll casting were est... To study the influence of roll casting process parameters on temperature and thermal-stress fields for the AZ31 magnesium alloy sheets,three-dimensional geometric and 3D finite element models for roll casting were established based on the symmetry of roll casting by ANSYS software.Meshing method and smart-sizing algorithm were used to divide finite element mesh in ANSYS software.A series of researches on the temperature and stress distributions during solidification process with different process parameters were done by 3D finite element method.The temperatures of both the liquid-solid two-phase zone and liquid phase zone were elevated with increasing pouring temperature.With the heat transfer coefficient increasing,the two-phase region for liquid-solid becomes smaller.With the pouring temperature increasing and the increase of casting speed,the length of two-phase zone rises.The optimized of process parameters(casting speed 2 m/min,pouring temperature 640 ℃ and heat transfer coefficient 15 kW/(m2·℃) with the water pouring at roller exit was used to produce magnesium alloy AZ31 sheet,and equiaxed grains with the average grain size of 50 μm were achieved after roll casting.The simulation results give better understanding of the temperature variation in phase transformation zone and the formation mechanism of hot cracks in plates during roll casting and help to design the optimized process parameters of roll casting for Mg alloy. 展开更多
关键词 magnesium alloy roll casting process parameter 3D finite element method THERMAL-STRESS
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Cellular/dendritic transition,dendritic growth and microhardness in directionally solidified monophasic Sn-2%Sb alloy 被引量:2
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作者 O.L.ROCHA T.A.COSTA +1 位作者 M.DIAS A.GARCIA 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第8期1679-1686,共8页
Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb(mass fraction) alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of t... Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb(mass fraction) alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of the microstructure. Continuous temperature measurements were made during solidification at different positions along the length of the casting and these temperature data were used to determine solidification thermal parameters, including the growth rate(VL) and the cooling rate(TR). High cooling rate cells and dendrites are shown to characterize the microstructure in different regions of the casting, with a reverse dendrite-to-cell transition occurring for TR5.0 K/s. Cellular(λc) and primary dendrite arm spacings(λ1) are determined along the length of the directionally-solidified casting. Experimental growth laws relating λc and λ1 to VL and TR are proposed, and a comparative analysis with results from a vertical upward directional solidification experiment is carried out. The influence of morphology and length scale of the microstructure on microhardness is also analyzed. 展开更多
关键词 Sn-Sb monophasic alloy directional solidification thermal paIameters inicrostructure reverse cellular/dendritictransition
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Influences of hot stamping parameters on mechanical properties and microstructure of 30MnB5 and 22MnB5 quenched in flat die 被引量:11
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作者 MU Yan-hong WANG Bao-yu +2 位作者 ZHOU Jing HUANG Xu LI Jun-ling 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第4期736-746,共11页
The influences of hot stamping parameters such as heating temperature,soaking time,deformation temperature and cooling medium on the phase transformation,microstructure and mechanical properties of 30MnB5 and 22MnB5 a... The influences of hot stamping parameters such as heating temperature,soaking time,deformation temperature and cooling medium on the phase transformation,microstructure and mechanical properties of 30MnB5 and 22MnB5 are investigated and analyzed in this work.The quenching experiment,tensile testing,hardness measurement and microstructure observation were conducted to obtain the mechanical and microstructural data.The results indicate that 30MnB5 possesses a higher tensile strength but a lower elongation than 22MnB5,if hot stamped at the same process parameter.The tensile strength and hardness of the hot stamped specimens decrease under inappropriate heating conditions for two reasons,insufficient austenitization or coarse austenite grains.The austenitic forming rate of 30MnB5 is higher than that of 22MnB5,because more cementite leads to higher nucleation rate and diffusion coefficient of carbon atom.More amount of fine martensite forms under the higher deformation temperature or the quicker cooling rate. 展开更多
关键词 high strength boron steel mechanical properties MICROSTRUCTURE hot stamping parameter
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Investigation on Zener-Hollomon parameter in the warm-hot deformation behavior of 20CrMnTi 被引量:9
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作者 YANG Hui LI Zhen-hong ZHANG Zhi-liang 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第8期1453-1460,共8页
The warm-hot deformation behavior of 20CrMnTi steel was studied with hot compression tests at temperature range of 1123-1273 K and strain rate of 0.1-20 s^-1. The activation energy for warm-hot deformation is 426.064 ... The warm-hot deformation behavior of 20CrMnTi steel was studied with hot compression tests at temperature range of 1123-1273 K and strain rate of 0.1-20 s^-1. The activation energy for warm-hot deformation is 426.064 KJ/mol. The influences of Zener-Hollomon parameter, strain and grain size imposing on the flow stress were analyzed in the temperature range of warm-hot forging. Creep theory and mathematical theory of statistics were used to obtain mathematical models of flow stress. The research and results provide scientific basis for controlling microstructure of forging process through Zener-Hollomon parameter. 展开更多
关键词 Zener-Hollomon parameter Warm-hot deformation 20CrMnTi Grain size
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Boundary layer flow of third grade nanofluid with Newtonian heating and viscous dissipation 被引量:8
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作者 S.A.Shehzad Tariq Hussain +2 位作者 T.Hayat M.Ramzan A.Alsaedi 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第1期360-367,共8页
Two-dimensional boundary layer flow of an incompressible third grade nanofluid over a stretching surface is investigated.Influence of thermophoresis and Brownian motion is considered in the presence of Newtonian heati... Two-dimensional boundary layer flow of an incompressible third grade nanofluid over a stretching surface is investigated.Influence of thermophoresis and Brownian motion is considered in the presence of Newtonian heating and viscous dissipation.Governing nonlinear problems of velocity, temperature and nanoparticle concentration are solved via homotopic procedure.Convergence is examined graphically and numerically. Results of temperature and nanoparticle concentration are plotted and discussed for various values of material parameters, Prandtl number, Lewis number, Newtonian heating parameter, Eckert number and thermophoresis and Brownian motion parameters. Numerical computations are performed. The results show that the change in temperature and nanoparticle concentration distribution functions is similar when we use higher values of material parameters β1 andβ2. It is seen that the temperature and thermal boundary layer thickness are increasing functions of Newtonian heating parameter γ.An increase in thermophoresis and Brownian motion parameters tends to an enhancement in the temperature. 展开更多
关键词 third grade nanofluid Newtonian heating viscous dissipation
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