Specular reflection in radiant heat transport across a spherical void

The emissivity factor for radiant heat transport across a spherical void with specular surfaces in a conducting solid is derived. To calculate the emissivity factor, the probability of all possible paths for radiation are formulated and summed. Emissivity factors for the diffuse and specular limits are compared. The resulting temperature dependence of void space radiation for several typical oxide materials is discussed.     

暖通专业设计中违反《工程建筑标准强制性条文》的某些问题及对相关条文的探讨

《工程建设标准强制性条文》意义，与暖通专业相关的主要内容，设计中某些违规问题与相关条文探讨。     

Rates and mechanisms of FeO reduction from slags

The rate of FeO reduction from CaO?SiO₂ slags has been determined in a stationary magnesia crucible with a graphite rod as the reductant. At 1650°±35°C, with a slag basicity CaO/SiO₂=1.2±0.3, and in the total iron concentration,C, range of 10 pct<C<40 pct, the specific rate,Q _E , of reduction in g-moles per min per sq cm was found to beQ _E =8.25×10^?6 C ^1.77 According to this and previous literature results, the reduction rates span three possible stages. The order of reaction in regard to concentration varies from first order in the low concentrations (0.1 pct<C<1.5 pct) to second order in the intermediate concentrations (1.5 pct<C<15 pct) and finally to 1.77th order in the high concentrations (15 pct<C<40 pct). The reduction reaction can best be interpreted by convective mechanisms because the observed rates fall between the rates of the chemically limited graphite gasification and the rates predicted from molecular diffusion.     

空间目标多种光谱观测方法的应用研究

光谱观测技术作为空间目标特征信息获取的一种方式,为空间目标表面材料的识别与性能分析提供了重要的解决方法.目前,光学信息采集元件的精密化程度高,因此空间目标观测技术也呈现多样性.基于长春人造卫星观测站1.2m空间目标光学望远镜,联合推扫式光栅光谱仪、光纤光谱仪、滤波器光谱相机三种终端设备,分别对恒星与空间目标开展观测并获取光谱数据;进一步,通过数据对观测技术进行适应性分析.结果 表明:三种方法均适用于恒星和高轨道空间目标的观测,可得到较好的光谱数据;滤波器光谱相机、光纤光谱仪适用于观测低轨道空间目标;而推扫式光栅光谱仪、滤波器光谱相机适用于观测中轨道空间目标.此外,滤波器光谱相机还可为精跟型空间目标光谱数据的获取提供观测参考.对于不同应用环境,对终端成本、光路调试复杂程度、获取光强度、可调整观测波段、数据处理复杂程度的对比分析可作为后续方案的参考.     

HDC型催化剂在间歇式聚丙烯装置上的应用

介绍了由中国石油化工集团公司石油化工科学研究院研制开发、北京燕化高新技术股份有限公司工业生产的HDC型高效催化剂，在呼和浩特石化公司间歇式液相本体法10kt/a聚丙烯生产装置上的工业应用试验情况，结果表明，HDC型高效催化剂活性高，单釜产量高，聚合反应前期放热均匀，操作易于控制。     

A universal two-way approach for estimating unknown frequencies for unknown number of sinusoids in a signal based on eigenspace analysis of Hankel matrix

We develop a novel approach to estimate the \(n\) unknown constituent frequencies of a noiseless signal that comprises of unknown number, \(n\), of sinusoids of unknown phases and unknown amplitudes. The new two-way approach uses two constraints to accurately estimate the unknown frequencies of the sinusoidal components in a signal. The new approach serves as a verification test for the estimated unknown frequencies through the estimated count of the unknown number of frequencies. The Hankel matrix, of the time domain samples of the signal, is used as a basis for further analysis in the Pisarenko harmonic decomposition. The new constraints, the existence factor and the component factor, have been introduced in the methodology based on the relationships between the components of the sinusoidal signal and the eigenspace of the Hankel matrix. The performance of the developed approach has been tested to correctly estimate any number of frequencies within a signal with or without a fixed unknown bias. The method has also been tested to accurately estimate the very closely spaced low frequencies.