期刊文献+
共找到17篇文章
< 1 >
每页显示 20 50 100
温压成形技术的研究进展 被引量:20
1
作者 李元元 肖志瑜 +2 位作者 倪东惠 周照耀 邵明 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2002年第11期15-20,共6页
主要介绍了温压技术研究概况 ,对其关键技术 (包括粉末、润滑剂、温压温度和温压系统 )、致密化机理、温压材料、数值模拟及其工业化应用的最新研究进展进行了较全面的综述 .目前 ,国外粉末冶金温压技术绝大部分受到专利保护 ,国内研究... 主要介绍了温压技术研究概况 ,对其关键技术 (包括粉末、润滑剂、温压温度和温压系统 )、致密化机理、温压材料、数值模拟及其工业化应用的最新研究进展进行了较全面的综述 .目前 ,国外粉末冶金温压技术绝大部分受到专利保护 ,国内研究时间较短 .因而 ,研究开发出我国拥有自主知识产权的温压技术 ,具有重要的现实意义 .在不久的将来 ,高性能铁基粉末冶金零件在汽车、机械工业中的应用将不断扩大 。 展开更多
关键词 粉末冶金 成形技术 研究进展 温压温度 材料 致密化机理
下载PDF
温压工艺及其关键技术 被引量:18
2
作者 肖志瑜 李元元 +1 位作者 邱诚 张文 《机械工程材料》 CAS CSCD 北大核心 2001年第1期18-21,共4页
简要介绍了温压工艺方法、特点和应用 ,并对其关键技术 (包括粉末、润滑剂、温压温度、温压系统和致密化机理 )的研究进展进行了综述 ,指出国内加快开展温压工艺的研究 。
关键词 工艺 粉末冶金 润滑剂 温压温度 系统
下载PDF
北朝鲜沃尔萨大理岩中水镁石形成的温度-压力条件研究 被引量:2
3
作者 金润成 李国武 +2 位作者 罗忠烈 金银河 赵勇宴 《矿物岩石地球化学通报》 CAS CSCD 北大核心 2018年第2期180-185,371,共6页
为厘清北朝鲜西南沃尔萨区新发现的含水镁石大理岩的矿物组成及其形成的温度-压力条件,对该区大理岩中的水镁石进行了XRD分析、化学分析、偏光显微镜观察和热分析,根据分析结果计算矿物组成,建立了方镁石形成的反应方程式,并对其热力学... 为厘清北朝鲜西南沃尔萨区新发现的含水镁石大理岩的矿物组成及其形成的温度-压力条件,对该区大理岩中的水镁石进行了XRD分析、化学分析、偏光显微镜观察和热分析,根据分析结果计算矿物组成,建立了方镁石形成的反应方程式,并对其热力学模型进行了分析。结果表明,大理岩的基本矿物组成及其平均含量(质量分数)为:水镁石30.33%,白云石10.51%,方解石56.66%,方镁石少量。水镁石是一种方镁石的水化反应产物,呈纤维状集合体。热力学模型解释表明,白云石分解为方镁石是在较低温(426-550℃)和低压(2.6 MPa以下)条件形成的,是在接近于地表的浅层区域,经过"长期地质作用过程"逐渐形成的。 展开更多
关键词 水镁石 方镁石 白云石分解 温度-条件 热力学模型
下载PDF
Analysis of DNA Methylation of Gracilariopsis lemaneiformis Under Temperature Stress Using the Methylation Sensitive Amplification Polymorphism(MSAP) Technique 被引量:1
4
作者 PENG Chong SUI Zhenghong +5 位作者 ZHOU Wei HU Yiyi MI Ping JIANG Minjie LI Xiaodong RUAN Xudong 《Journal of Ocean University of China》 SCIE CAS CSCD 2018年第3期623-631,共9页
Gracilariopsis lemaneiformis is an economically important agarophyte, which contains high quality gel and shows a high growth rate. Wild population of G. lemaneiformis displayed resident divergence, though with a low ... Gracilariopsis lemaneiformis is an economically important agarophyte, which contains high quality gel and shows a high growth rate. Wild population of G. lemaneiformis displayed resident divergence, though with a low genetic diversity as was revealed by amplified fragment length polymorphism(AFLP) and simple sequence repeat(SSR) analyses. In addition, different strains of G. lemaneiformis are diverse in morphology. The highly inconsistence between genetic background and physiological characteristics recommends strongly to the regulation at epigenetic level. In this study, the DNA methylation change in G. lemaneiformis among different generation branches and under different temperature stresses was assessed using methylation sensitive amplified polymorphism(MSAP) technique. It was shown that DNA methylation level among different generation branches was diverse. The full and total methylated DNA level was the lowest in the second generation branch and the highest in the third generation. The total methylation level was 61.11%, 60.88% and 64.12% at 15℃, 22℃ and 26℃, respectively. Compared with the control group(22℃), the fully methylated and totally methylated ratios were increased in both experiment groups(15℃ and 26℃). All of the cytosine methylation/demethylation transform(CMDT) was further analyzed. High temperature treatment could induce more CMDT than low temperature treatment did. 展开更多
关键词 DNA methylation/demethylation EPIGENETICS Gracilariopsis lemaneiformis MSAP temperature stress
下载PDF
Research on Critical Flow of Water under Supercritical Pressures in Nozzles 被引量:3
5
作者 Yuzhou Chen Minfu Zhao Chunsheng Yang Keming Bi Kaiwen Du Shuming Zhang 《Journal of Energy and Power Engineering》 2012年第2期201-208,共8页
An experiment on critical flow of water was conducted in two nozzles of 1.41 mm in diameter and 4.35 mm in length with rounded-edge and sharp-edge respectively, covering the ranges of inlet pressure of 22.1-29.1 MPa a... An experiment on critical flow of water was conducted in two nozzles of 1.41 mm in diameter and 4.35 mm in length with rounded-edge and sharp-edge respectively, covering the ranges of inlet pressure of 22.1-29.1 MPa and inlet temperature of 38-474 ℃. More than 200 data points were obtained and the characteristics and parametric trends were investigated. In the region of near and beyond pseudo-critical temperature the thermal-equilibrium is dominant, and the flow rate can be estimated by the modified homogeneous equilibrium model. In the below pseudo-critical region the results exhibit scattered feature as a result of hysteresis effect in the onset of vaporization, characterizing a bifurcation behavior. This effect is more significant in the nozzle with sharp-edge, especially at higher pressure. For temperature well below the pseudo-critical point, the flow is not at critical condition and the flow rate can be represented by the Bernoulli equation reasonably. 展开更多
关键词 Critical flow CHOKING NOZZLE supercritical pressure THERMAL-EQUILIBRIUM reactor safety.
下载PDF
Pressure and Doping Effects on Critical Temperature in MgB_2 and Nonmagnetic Borocarbides within Two-Band Eliashberg Theory
6
作者 I.N.Askerzade 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第6期1181-1184,共4页
Critical temperature of Mg1-xAlxB2, MgB2-xCx are calculated using two-band Eliashberg theory in intermediate e-ph coupling. Analytical calculations are conducted for different values of doping parameters x in this com... Critical temperature of Mg1-xAlxB2, MgB2-xCx are calculated using two-band Eliashberg theory in intermediate e-ph coupling. Analytical calculations are conducted for different values of doping parameters x in this compounds. Pressure effects on critical temperature in MgB2 and nonmagnetic borocarbide YNi2B2C are also investigated. Results is compared with available experimental data and good agreement is achieved. 展开更多
关键词 Jtwo-band superconductivity Eliashberg theory magnesium diboride nonmagnetic borocarbides
下载PDF
Critical Temperature Characteristics of Layered High-Temperature Superconductor Under Pressure
7
作者 LIANG Fang-Ying 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第4期761-764,共4页
We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pressure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature s... We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pressure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature superconductor. If the pressure is not a constant, we have a relation of quadratic equation between the pressure and the temperature of layered high-temperature superconductor. In a special case, we find the critical temperature decreases with further increasing pressure. In another special ease, the critical temperature increases with further increasing pressure. 展开更多
关键词 pressure effects transition temperature variations layered superconductor
下载PDF
Optimization Analysis of High Temperature Heat Pump Coupling to Desiccant Wheel Air Conditioning System 被引量:1
8
作者 盛颖 张于峰 +2 位作者 房磊 聂金哲 马丽筠 《Transactions of Tianjin University》 EI CAS 2014年第3期182-188,共7页
The high temperature heat pump and desiccant wheel(HTHP&DW) system can make full use of heat released from the condenser of heat pump for DW regeneration without additional heat. In this study, DW operation in the... The high temperature heat pump and desiccant wheel(HTHP&DW) system can make full use of heat released from the condenser of heat pump for DW regeneration without additional heat. In this study, DW operation in the HTHP&DW system was investigated experimentally, and the optimization analysis of HTHP&DW system was carried out. The performance of DW had influence on the dehumidification(evaluated by dehumidification and regeneration effectiveness) and cooling load(evaluated by thermal and adiabatic effectiveness). The results show that the enthalpy increase occurred in all the experiments. Compared to the isosteric heat, heat accumulation in the desiccant and matrix material and heat leakage from regeneration side to process side have greater influence on the adiabatic effectiveness. Higher regeneration temperature leads to lower adiabatic effectiveness that increases more cooling load of the system. When the regeneration temperature is 63℃, the maximal dehumidification effectiveness is 35.4% and the satisfied adiabatic effectiveness is 88%, which contributes to the optimal balance between dehumidification and cooling. 展开更多
关键词 desiccant wheel DEHUMIDIFICATION adiabatic effectiveness performance optimization
下载PDF
Determination of the High Temperature Stress Tolerances of Bread Wheat Genotypes
9
作者 Zahit Kaylhan Korkut Alpay Balkan +1 位作者 Ismet Baser Oguz Bilgin 《Journal of Life Sciences》 2017年第7期346-354,共9页
Thirty bread wheat genotypes were used as material during the 2014-2015 cropping season. The experimental layout was a randomized complete block design with 3 replications. The sowing rate was 500 seeds square meter. ... Thirty bread wheat genotypes were used as material during the 2014-2015 cropping season. The experimental layout was a randomized complete block design with 3 replications. The sowing rate was 500 seeds square meter. Sowing was done in plots of 6 rows (1.2 m × 5 m, spaced 20 cm apart) in Namlk Kemal University, Faculty of Agriculture, Field Crops Department experimental area. Two sowing times were performed. First sowing was made in November suggested usual (standard) and second one was made in January as delayed sown in order to push growing stages of plants into periods in which heat stress is expected will be effected. Sowing times were allotted to main-plots while genotypes were allotted to sub-plots. When the bread wheat varieties and lines used in the experiment are evaluated in terms of tolerance to high temperature, it was shown that Dropia and Nota varieties and CIMMYT-HTN 2014/15-2, CIMMYT-HTN 2014/15 -6, CIMMYT-HTN 2014/15 - 10 lines were better tolerance to high temperature. However, it was noticed that these genotypes were not included in the first groups in terms of grain yield. It is possible to utilize these genotypes as a genitor in cross-breeding programs for breeding studies for tolerance to high temperatures. 展开更多
关键词 Heat tolerance bread wheat advanced lines heat sensitive
下载PDF
Square concrete columns strengthened with carbon fiber reinforced plastics sheets at low temperatures 被引量:1
10
作者 马芹永 卢小雨 《Journal of Central South University》 SCIE EI CAS 2009年第5期835-840,共6页
Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceabilit... Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature. 展开更多
关键词 carbon fiber reinforced plastics (CFRP) sheet square concrete column stress--strain model
下载PDF
Relationship Between North Pacific SST Anomalies and the Atmospheric Circulation Anomalies in January 2008 被引量:1
11
作者 WANG Jianbo FAN Lei LIU Qinyu 《Journal of Ocean University of China》 SCIE CAS 2010年第1期11-15,共5页
Based on the NCEP (National Centers for Environmental Prediction) data,the relationship between the Sea Surface Temperature Anomalies (SSTAs) in the North Pacific and the atmospheric circulation anomalies in January 2... Based on the NCEP (National Centers for Environmental Prediction) data,the relationship between the Sea Surface Temperature Anomalies (SSTAs) in the North Pacific and the atmospheric circulation anomalies in January 2008 is analyzed in this study.The SSTA mode most correlated with the Geopotential Height anomalies (GHAs) in January 2008 in the North Pacific exhibited a basin-wide horseshoe pattern with a warm center in November 2007.This persistent SSTA pattern would induce positive GHAs in the Aleutian Low area and East Asia and the northward extension of the West Pacific Subtropical High in January 2008 by maximum diabatic heating in the atmosphere over the Kuroshio Oyashio Extension (KOE) area,leading to the occurence of the circumpolar trough-ridge wave train anomaly in January 2008. 展开更多
关键词 North Pacific sea surface temperature geopotential height Singular Value Decomposition analysis
下载PDF
Optimal Analysis of Pure Low-Temperature Waste Heat Recovery Generation System
12
作者 X.B. Wang Q.X. Zhao J.P. Si S.E. Hui T.M. Xu 《Journal of Energy and Power Engineering》 2011年第1期10-16,共7页
In this paper, a detailed thermodynamic analysis of the pure low-temperature waste heat recovery generation system is presented. The parameters affecting the system performance are compared to obtain the most signific... In this paper, a detailed thermodynamic analysis of the pure low-temperature waste heat recovery generation system is presented. The parameters affecting the system performance are compared to obtain the most significant ones; furthermore, parameter values are optimized for the largest power generating capability of the system. It is found that the most important parameters are inlet flue gas temperature, steam pressure and the pinch point temperature difference. There is an optimal superheated steam pressure value for giving the maximum generation power per unit flue gas. With the increase of inlet flue gas temperature, the generating power increases and the optimized steam pressure rises as well. However, with increase in pinch point temperature difference, the generating power decreases and the optimized steam pressure decreases as well. The theoretical calculation provides a theoretical basis for the parameters optimization in the design of the pure low-temperature waste heat recovery eeneration swtem 展开更多
关键词 Waste heat recovery generation optimal analysis steam pressure pinch point.
下载PDF
First-principles calculations of elasticity of minerals at high temperature and pressure 被引量:4
13
作者 WU ZhongQing WANG WenZhong 《Science China Earth Sciences》 SCIE EI CAS CSCD 2016年第6期1107-1137,共31页
The elasticity of minerals at high temperature and pressure (PT) is critical for constraining the composition and temperature of the Earth's interior and understand better the deep water cycle and the dynamic Earth... The elasticity of minerals at high temperature and pressure (PT) is critical for constraining the composition and temperature of the Earth's interior and understand better the deep water cycle and the dynamic Earth. First-principles calcula- tions without introducing any adjustable parameters, whose results can be comparable to experimental data, play a more and more important role in investigating the elasticity of minerals at high PT mainly because of (1) the quick increasing of computational powers and (2) advances in method. For example, the new method reduces the computation loads to one-tenth of the traditional method with the comparable precise as the traditional method. This is extraordinarily helpful because first-principles calculations of the elasticity of minerals at high PT are extremely time-consuming. So far the elasticity of most of lower mantle minerals has been investigated in detail. We have good idea on the effect of temperature, pressure, and iron concentration on elasticity of main minerals of the lower mantle and the unusual softening in bulk modulus by the spin crosso- ver of iron in ferropericlase. With these elastic data the lower mantle has been constrained to have 10-15 wt% ferropericlase, which is sufficient to generate some visible effects of spin crossover in seismic tomography. For example, the spin crossover causes that the temperature sensitivity of P wave at the depth of -1700 km is only a fraction of that at the depth of -2300 kin. The disruptions of global P wave structure and of P wave image below hotspots such as Hawaii and Iceland at similar depth are in consistence with the spin crossover effect of iron in ferropericlase. The spin crossover, which causes anomalous ther- modynamic properties of ferropericlase, has also been found to play a control role for the two features of the large low shear velocity provinces (LLSVPs): the sharp edge and high elevation up to 1000 km above core-mantle boundary. All these results clearly suggest the spin crossover of iron in the lower mantle. The theoretical investigations for the elasticity of minerals at the upper mantle and water effect on elasticity of minerals at the mantle transition zone and subducting slab have also been con- ducted extensively. These researches are critical for understanding better the composition of the upper mantle and water dis- tribution and transport in the Earth's mantle. Most of these were static calculations, which did not include the vibrational (temperature) effect on elasticity, although temperature effect on elasticity is basic because of high temperature at the Earth's interior and huge temperature difference between the ambient mantle and the subducting slab. Including temperature effect on elasticity of minerals should be important future work. New method developed is helpful for these directions. The elasticity of iron and iron-alloy with various light elements has also been calculated extensively. However, more work is necessary in order to meet the demand for constraining the types and amount of light elements at the Earth's core. Keywords Mantle temperature, Mantle composition, Composition of Earth's core, Ab initio method 展开更多
关键词 Mantle temperature Mantle composition Composition of Earth's core Ab initio method
原文传递
The influence of environment temperatures on single crystalline and polycrystalline silicon solar cell performance 被引量:7
14
作者 WEN Cai FU Chao +3 位作者 TANG JinLong LIU DeXiong HU SiFu XING ZhiGang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第2期235-241,共7页
The influence of the cell temperature (named interior environment temperature) and ambient air temperature (named exterior environment temperature) on the open-circuit voltage,short-circuit current,and output power ha... The influence of the cell temperature (named interior environment temperature) and ambient air temperature (named exterior environment temperature) on the open-circuit voltage,short-circuit current,and output power has been carefully studied for the Si solar cells.The results show that one of the environment temperatures plays the major role,and the temperature dependence of device performance parameters is different for single crystalline and polycrystalline Si solar cells.Furthermore,the ambient air temperature builds a bridge for the comparison of the effect between the cell temperature and the illumination intensity on solar cell performance.Based on the experimental results,the reasons which cause the difference of the environment temperatures dependence are analyzed. 展开更多
关键词 Si solar cell cell temperature ambient air temperature illumination intensity cell performance
原文传递
Observation of a bi-critical point between antiferromagnetic and superconducting phases in pressurized single crystal Ca0.73La0.27FeAs2 被引量:3
15
作者 Yazhou Zhou ShanJiang +14 位作者 Qi wu Vladimir A.Sidorov Jing Guo Wei Yi Shan Zhang Zhe Wang HonghongWang shu Cai Ke Yang Sheng Jiang Aiguo Li Ni Ni Guangming Zhang Liling Sun Zhongxian Zhao 《Science Bulletin》 SCIE EI CAS CSCD 2017年第12期857-862,共6页
One of the most strikingly universal features of the high-temperature superconductors is that the super- conducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these ... One of the most strikingly universal features of the high-temperature superconductors is that the super- conducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these two phases poses a long-standing challenge. It is commonly believed that, as the antifer- romagnetic transition temperature is continuously suppressed to zero, there appears a quantum critical point, around which the existence of antiferromagnetic fluctuation is responsible for the development of the superconductivity. In contrast to this scenario, we report the observation of a bi-critical point identified at 2,88 GPa and 26.02 K in the pressurized high-quality single crystal Cao.73Lao.27FeAs2 by com- plementary in-situ high pressure measurements. At the critical pressure, we find that the antiferromag- netism suddenly disappears and superconductivity simultaneously emerges at almost the same temperature, and that the external magnetic field suppresses the superconducting transition temperature but hardly affects the antiferromagnetic transition temperature. 展开更多
关键词 Iron pnictide superconductorBi-critical pointSuperconductivityAntiferromagnetic orderHigh pressure
原文传递
Current-voltage characteristics of voltage-biased Tl_2Ba_2CaCu_2O_8 intrinsic Josephson junctions
16
作者 WANG Pei XIE Wei +6 位作者 HU Lei LIU Xin JI Lu HE Ming ZHANG Xu ZHAO XinJie YAN ShaoLin 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第12期2242-2245,共4页
The voltage-biased current-voltage (I-V) characteristics of intrinsic Josephson junctions (IJJs), which are fabricated with misa- ligned high temperature superconducting Tl2Ba2CaCu2O8 (T1-2212) thin film, are in... The voltage-biased current-voltage (I-V) characteristics of intrinsic Josephson junctions (IJJs), which are fabricated with misa- ligned high temperature superconducting Tl2Ba2CaCu2O8 (T1-2212) thin film, are investigated experimentally. Three charac- teristic regions in the I-V curve are observed at 47 K. In the low voltage part, the current firstly increases and then decreases slowly with increasing the biased voltage, which is shown as a bump. In the next region, the current slightly increases with in- creasing the biased voltage until a sudden decrease of the current appears. Thereafter, branch structure forms with increasing the voltage on the I-V characteristic. The influence of the self-heating on the I-V characteristics is investigated and the temper- ature dependence of the I-V characteristics is measured to explore these characteristics in detail. 展开更多
关键词 intrinsic Josephson junctions voltage-biased I-V characteristics
原文传递
Stable single-photon detection based on Si-avalanche photodiode in a large temperature variation range
17
作者 颜佩琴 李召辉 +5 位作者 师亚帆 冯百成 杜秉乘 杜艳伟 潭天乐 吴光 《Optoelectronics Letters》 EI 2015年第5期321-324,共4页
In this paper, we present a stable single-photon detection method based on Si-avalanche photodiode(Si-APD) operating in Geiger mode with a large temperature variation range. By accurate temperature sensing and direct ... In this paper, we present a stable single-photon detection method based on Si-avalanche photodiode(Si-APD) operating in Geiger mode with a large temperature variation range. By accurate temperature sensing and direct current(DC) bias voltage compensation, the single-photon detector can work stably in Geiger mode from-40 °C to 35 °C with an almost constant avalanche gain. It provides a solution for single-photon detection at outdoor operation in all-weather conditions. 展开更多
关键词 photodiode photon weather compensation fitting outdoor tempera illumination stabilize amplifier
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部