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排序方式: 共有2298条查询结果,搜索用时 15 毫秒
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Y Katsumura 《辐射研究与辐射工艺学报》2005,23(2):68-68
It is known that water exists in supercritical state above 374C and 22.1MPa, where gas phase and liquid phase are merged into a single phase. In the supercritical state, the density is controllable by changing the pressure. The properties such as the ionic product, solubilities of salts, gas and organic compounds, and dielectric constant of supercritical water are very different from those of water at room temperature.Recently much attention has been paid to supercritical water because many possible applications such as synthesis of functional materials, waste oxidation, and biomass conversion have been proposed by using above peculiar properties of the supercritical water. Thus, much intensive work is in progress all over the world. In addition, a new concept of nuclear reactor using the supercritical water as a coolant has been proposed, which has been chosen by DOE, USA as one of the forth generation nuclear reactors.Therefore, radiation chemistry study of the supercritical water seems inevitably important, yet little work has been done so far. We started radiation chemistry study of supercritieal water by pulse radiolysis and γ radiolysis five years ago. We have observed hydrated electrons as a first target. We also measured inorganic radicals, metal ions, organic radicals in high temperature and supercritical water by a pulse radiolysis technique. It was found that absorption spectra of the transient species are dependent on temperature. Some transients show red-shift, and some bands are blue-shifted, with increasing temperatures. A G-value evaluation of water decomposition products was also done by using methyl viologen as a scavenger and it was revealed that the values are significantly dependent not only on temperature but also on density in supercritical water. An extended study on the behavior of solvated eleclions in different alcohols at high temperatures and super critical state is also in progress. 相似文献
94.
A resonance tube is an important component of a thermoacoustic engine, which has great influence on the performance of the thermoacoustically driven pulse tube refrigerator. A standing wave thermoacoustic engine is simulated with linear thermoacoustics. Computed results show that an appropriate accretion of the resonance tube length may lead to a decrease of the working frequency and an increase of the pressure amplitude, which will improve the match between the thermoacoustic engine and the pulse tube refrigerator. The theoretical prediction is verified by experiments. A refrigeration temperature as low as 88.6 K has been achieved with an optimized length of the resonance tube, helium as working gas, and 2200 W of heating power. 相似文献
95.
A single-stage G-M type pulse tube cooler (PTC) was designed and tested to explore the lowest attainable refrigeration temperature and to further improve the cooling performance in the temperature range of 15-40 K. The magnetic material Er3Ni was used as part of the regenerative material besides the phosphor-bronze and the lead so as to improve the efficiency of the regenerator. With an input power of 6 kW, a lowest no-load refrigeration temperature of 12.6 K was obtained, which is a new record for the single-stage PTC. The cooling capacity at 15-40 K was also significantly improved, which may extend the application of the single-stage PTC for the cooling of superconductors and cryopumps. 相似文献
96.
非晶Fe78Si9B13在脉冲磁场作用下纳米晶化及物理机理 总被引:7,自引:2,他引:7
采用TEM和穆斯堡尔谱技术,研究了非晶合金Fe78Si9B13晶化的结构与脉冲磁场强度的关系,并对低频脉冲磁场致非晶合金纳米晶化的物理机制进行了理论研讨。一定频率下的脉冲磁场,将使非晶合金磁致伸缩的能量降低非晶合金的形核势垒,从而使非晶合金得以晶化。实验对非晶合金Fe78Si9B13进行了两种脉冲磁场处理:脉冲频率固定,磁场强度不断增加;磁场强度固定,脉冲频率不断增加。结果表明,低频脉冲磁场处理可使非晶合金Fe78Si9B13发生纳米晶化;晶化量与磁场强度不呈线性关系,而是存在一极值的曲线分布。 相似文献
97.
己烯雌酚(DES)是一种活泼的环境雌激素。利用流动池脉冲辐解手段对其活性瞬态粒子的动力学特性作了初步研究,发现己烯雌酚自由基的苯环间双键可能是羟自由基优先进攻破坏的一个位点。该化合物对高能电子束非常敏感,通过自由基机理被降解。研究结果对DES环境降解机理和生物毒理,对探索解毒、环境修复等,具有一定的指导意义。 相似文献
98.
本文介绍了在Windows98下利用VxD技术编写中断处理程序.并且利用VC 6.0的多线程技术实现转速的实时测量,并实现了数据存储、再现功能,可用于数据采集,实时控制等领域。 相似文献
99.
无传感器永磁同步电机矢量控制中转子初始位置的估算方法 总被引:6,自引:0,他引:6
介绍了一种在电机静止时检测其转子初始位置的方法。该方法利用永磁同步电机定子铁心的饱和特性 ,通过给电机施加一系列不同方向的电压脉冲 ,检测并比较其相应的定子电流的方法来估算出转子的初始位置 相似文献
100.
龚成龙 《自动化与仪器仪表》1997,(2):29-32
本文介绍一种基于被控对象脉冲响应的模型辨识方法及PID参数自整定控制器的设计原理,并给出应用实例。 相似文献