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聚2.6—萘二甲酸乙二酯的结晶行为
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作者 安宝珠 关家玉 徐懋 《中国科学院研究生院学报》 CAS CSCD 1991年第1期54-60,共7页
用光学解偏振法测定了2.6—PEN的结晶速度的温度依赖性,得出其快结晶速度区域是在180℃至230℃之间,而在低于180℃或高于230℃的温度区域,结晶速度都是慢的。测定了不同结晶度试样的动态力学—温度谱,用以研究其结晶行为,得出α损耗峰... 用光学解偏振法测定了2.6—PEN的结晶速度的温度依赖性,得出其快结晶速度区域是在180℃至230℃之间,而在低于180℃或高于230℃的温度区域,结晶速度都是慢的。测定了不同结晶度试样的动态力学—温度谱,用以研究其结晶行为,得出α损耗峰随结晶度的变化。此外,将上述各实验结果与同法测定的PET的结果进行了对比,发现2.6~PEN与PET的结晶行为的相似性。 展开更多
关键词 聚2.6—萘二甲酸乙二酯 光学解偏振法 结晶行为 动态力学测量 结晶度
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Influence of substituting Ni with Co on hydriding and dehydriding kinetics of melt spun nanocrystalline and amorphous Mg_2Ni-type alloys 被引量:2
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作者 张羊换 赵栋梁 +3 位作者 李保卫 马志鸿 郭世海 王新林 《Journal of Central South University》 SCIE EI CAS 2011年第2期303-309,共7页
In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys,Ni in the alloy is substituted by element Co. The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1-xCox (x=0,0.1,0.2,0.3,0.4) alloys w... In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys,Ni in the alloy is substituted by element Co. The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1-xCox (x=0,0.1,0.2,0.3,0.4) alloys were synthesized by melt-spinning technique. The structures of the as-cast and spun alloys were studied with an X-ray diffractometer (XRD) and a high resolution transmission electronic microscope (HRTEM). An investigation on the thermal stability of the as-spun alloys was carried out with a differential scanning calorimeter (DSC). The hydrogen absorption and desorption kinetics of the alloys were measured with an automatically controlled Sieverts apparatus. The results demonstrate that the substitution of Co for Ni does not alter the major phase of Mg2Ni but results in the formation of secondary phase MgCo2. No amorphous phase is detected in the as-spun Co-free alloy,but a certain amount of amorphous phase is clearly found in the as-spun Co-containing alloys. The substitution of Co for Ni exerts a slight influence on the hydriding kinetics of the as-spun alloy. However,it dramatically enhances the dehydriding kinetics of the as-cast and spun alloys. As Co content (x) increases from 0 to 0.4,the hydrogen desorption capacity increases from 0.19% to 1.39% (mass fraction) in 20 min for the as-cast alloy,and from 0.89% to 2.18% (mass fraction) for the as-spun alloy (30 m/s). 展开更多
关键词 Mg2Ni-type alloy MELT-SPINNING substituting NI Co structure HYDRIDING dehydriding KINETICS
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Study on Measuring Device for Bearing Clearance of Hemisphere Dynamic Pressure Motor
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作者 YAN Xiaojun YU Detao TANG Zhaofang 《Aerospace China》 2018年第1期3-8,共6页
The clearance of the hemisphere dynamic pressure motor is small and difficult to measure, the measurement method of micro clearance is studied. The shortcomings of the original measurement method are analyzed, and a c... The clearance of the hemisphere dynamic pressure motor is small and difficult to measure, the measurement method of micro clearance is studied. The shortcomings of the original measurement method are analyzed, and a clearance measuring device for the hemisphere dynamic pressure motor is designed, which improves the measurement efficiency and stability. 展开更多
关键词 hemisphere dynamic pressure motor measurement of micro clearance precision measurement research on device
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Dynamics of quantum zeno and anti-zeno efects in an open system 被引量:3
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作者 ZHANG Peng AI Qing +2 位作者 LI Yong XU DaZhi SUN ChangPu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第2期194-207,共14页
We provide a general dynamical approach for the quantum Zeno and anti-Zeno effects in an open quantum system under repeated non-demolition measurements. In our approach the repeated measurements are described by a gen... We provide a general dynamical approach for the quantum Zeno and anti-Zeno effects in an open quantum system under repeated non-demolition measurements. In our approach the repeated measurements are described by a general dynamical model without the wave function collapse postulation. Based on that model, we further study both the short-time and long-time evolutions of the open quantum system under repeated non-demolition measurements, and derive the measurement-modified decay rates of the excited state. In the cases with frequent ideal measurements at zero-temperature, we re-obtain the same decay rate as that from the wave function collapse postulation (Nature, 2000, 405: 546). The correction to the ideal decay rate is also obtained under the non-ideal measurements. Especially, we find that the quantum Zeno and anti-Zeno effects are possibly enhanced by the non-ideal natures of measurements. For the open system under measurements with arbitrary period, we generally derive the rate equation for the long-time evolution for the cases with arbitrary temperature and noise spectrum, and show that in the long-time evolution the noise spectrum is effectively tuned by the repeated measurements. Our approach is also able to describe the quantum Zeno and anti-Zeno effects given by the phase modulation pulses, as well as the relevant quantum control schemes. 展开更多
关键词 quantum Zeno effect quantum anti-Zeno effect quantum measurement
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