太阳能热气流电站系统研究

由于现有模型不足以准确描述太阳能热气流发电系统的物理机制,本文提出一个更完善的数学模型去分析太阳能热气流电站系统的相对压力分布和系统抽力．模型中考虑了太阳辐射和系统尺寸参数对系统相对压力和系统抽力的影响。以西班牙试验电站为例进行数值模拟,探索系统尺寸参数和太阳辐射对系统相对压力和系统抽力的影响。数值计算结果与理论分析具有良好的一致性．     

Construction and Application of Functional Brain Network Based on Entropy

Functional brain network (FBN) is an intuitive expression of the dynamic neural activity interaction between different neurons, neuron clusters, or cerebral cortex regions. It can characterize the brain network topology and dynamic properties. The method of building an FBN to characterize the features of the brain network accurately and effectively is a challenging subject. Entropy can effectively describe the complexity, non-linearity, and uncertainty of electroencephalogram (EEG) signals. As a relatively new research direction, the research of the FBN construction method based on EEG data of fatigue driving has broad prospects. Therefore, it is of great significance to study the entropy-based FBN construction. We focus on selecting appropriate entropy features to characterize EEG signals and construct an FBN. On the real data set of fatigue driving, FBN models based on different entropies are constructed to identify the state of fatigue driving. Through analyzing network measurement indicators, the experiment shows that the FBN model based on fuzzy entropy can achieve excellent classification recognition rate and good classification stability. In addition, when compared with the other model based on the same data set, our model could obtain a higher accuracy and more stable classification results even if the length of the intercepted EEG signal is different.     

应用于空间惯性传感器的压电驱动器的性能测试

为保证空间惯性传感器的正常在轨运行,在发射阶段需保证测试质量固定以避免与周围电容极板的接触碰撞;到达预定轨道后再重新捕获并以最小残余线速度将测试质量释放至精确位置,保持自由悬浮状态。测试质量的捕获定位对驱动器提出高精度的要求。本文针对在太空中捕获定位释放测试质量所用的压电直线驱动器进行了设计定制与性能测试。试验结果表明:该定制的压电驱动器最小步长小于1 nm,但步长稳定性误差较大;150 V工作电压条件最大驱动力达72 N;单步行进驱动力稳定;夹持测试质量过程中,驱动力稳定,稳定性偏差为0.16%。满足捕获、定位、释放机构的使用需求。     

Coupled membrane process applied to fruit juice concentration

A coupled membrane process of membrane distillation and osmotic evaporation, where the solutions were thermostated separately at different temperatures, was developed. Enhanced water flux was obtained since the total driving force of the coupled process was higher than the sum of the driving forces of single processes. Apple, raspberry, sour cherry, red, and black currant juices were concentrated by the novel, mild technique. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

木质素磺酸钠在氧化铁表面的吸附驱动力

研究吸附介质的pH值、 尿素及盐类对木质素磺酸钠(SL)在氧化铁表面吸附性能的影响规律, 结果表明, 络合能力较强的柠檬酸钠使SL的吸附量几乎减少至零, 较弱络合能力的亚硫酸钠使SL的吸附量具有一定程度的降低, 而无络合能力的硫酸钠增大了SL的吸附量. 说明SL的羧基与氧化铁之间的络合吸附驱动力对吸附起主导作用, 磺酸基对其在氧化铁上吸附的影响很弱. 采用氯化锂屏蔽部分羧基后SL在氧化铁上的吸附量也有所降低, 进一步证明了羧基与氧化铁表面的络合作用是其吸附的主要驱动力.     

基于表面分析技术和铁谱技术的某重载履带车辆主离合器摩擦副失效机理研究

利用扫描电子显微镜、能量色散谱仪及铁谱仪分析了某重载履带车辆主离合器分离机构中的活动盘弹子槽的磨损失效机理.结果表明:磨损表面存在明显的犁沟痕迹和点蚀坑,而粘着磨损迹象不明显;铁谱分析结果表明润滑脂中的磨粒主要包括典型的粘着磨粒、接触疲劳磨粒和腐蚀磨粒;磨损表面的主要失效机制为磨料磨损、粘着磨损、接触疲劳磨损和腐蚀磨损的综合作用;采用联合表面分析技术和铁谱技术研究材料表面磨损失效机理具有一定的优越性.     

Sensitivity analysis of regenerative queuing models

Queuing models described as regenerative processes driven by several sequences are under investigation. Occurrence times in these sequences are supposed to be asynchronous, in general. Sensitivity coefficients that are derivatives of some stationary performance measures with respect to definite parameters as well as derivatives of higher orders are derived for such queuing models. These sensitivity coefficients can be evaluated by simulation.     

热法磷酸生产过程推动力和节能改造的分析

本文以有余热回收的两步法热法磷酸生产系统为研究对象,提出了热法磷酸生产过程推动力及其节能潜力的概念和计算方法,通过对实际生产系统进行的能量分析,说明了考虑过程推动力的能量分析的科学性和实用性。并在分析导致内部(火用)损失主要因素的基础上,提出了两个节能再改造构想,通过对再改造前后生产系统的能量利用、经济效果和环境影响的对比分析,证明了再改造构想具有可行性。     

The Driving Forces in the Inclusion Complexation of Cyclodextrins

The driving forces leading to the inclusion complexation of cyclodextrins were reviewed, which included the electrostatic interaction, van der Waalsinteraction, hydrophobic interaction, hydrogen bonding, release of conformational strain,exclusion of cavity-bound high-energy water, and charge–transferinteraction. It was shown that except for the release of conformation strain and exclusion of cavity-bound water, the otherinteractions were indeed contributive to the complex formation. However, it was concludedthat the enthalpy and entropy changes of the complexation were not good criteria to be used injudging whether a particular driving force was present or important, mainly because of theoccurrence of enthalpy-entropy compensation. On the other hand, the multivariate quantitativestructure-activity relationship analyses usually could illustrate which driving forces wereimportant in certain inclusion complexation systems.     

Solvent Electrostatic and Covalent Effects on Complexation Thermodynamics

A new method is suggested for estimating the electrostatic and covalent contributions to the standard Gibbs energy, enthalpy and entropy of complexation reactions upon transfer from water (W) to non-aqueous and mixed aqueous organic solvents (S). The equations derived for calculation of the electrostatic (temperature dependent) contributions are based on the temperature dependences of thermodynamic parameters of complexation in aqueous solution and the temperature dependence of the dielectric constant of water. These contributions correspond to the transfer process in water from T₁ = 298.15 K to a higher temperature (T₂) at which water has the same dielectric constant as does the solvent S at 298.15 K (εW(T₂) = εS(T₁)). The covalent (temperature independent) contributions are calculated at isodielectric conditions (transfer from water at T₂ to S at T₁) using the corresponding thermodynamic cycle. Application of the model to an analysis of solvent effects is demonstrated and discussed with an example given of a typical complexation reaction between K⁺ and 18-crown-6 in pure non-aqueous and water-acetonitrile mixed solvents.