用于催化裂化装置产率预测的Filter-Wrapper特征变量选择方法

催化裂化过程是重质油轻质化的重要手段,为了研究操作条件、原料性质等因素对产品分布的影响,通常需要对催化裂化过程建立准确可靠的数学模型。选择合适的输入变量对模型预测效果有着较大的影响,而在现有的催化裂化装置模型中,输入变量的选取主要依赖于对催化裂化机理的理解。本文从数据驱动建模的角度出发,提出一种Filter法与Wrapper法联合使用的特征子集选择方法。该方法在输入变量选取的过程中不依赖于催化裂化的先验知识,是一种数据驱动的自发的特征变量选择过程。以某炼油厂催化裂化装置为研究对象,利用该装置的生产数据分别选择用于干气和焦炭产率预测模型的输入变量,建立了预测精度高、输入变量数目适中的模型。此外,该方法为催化裂化装置建模的变量选取提供了新角度。     

The combination of 1-octyl-3-methylimidazolium tetrafluorborate with TBAB or THF on CO2 hydrate formation and CH4 separation from biogas

[C₈min] BF₄ was used in this work to combine with TBAB or THF for the investigation about thermodynamic and kinetic additives on CO₂ and CH₄/CO₂ hydrates. The results show that[C₈min] BF₄ has the inhibition effect on the equilibrium of hydrate formation. About the kinetic study,[C₈min] BF₄ could improve the rate of CO₂ hydrate formation and increase the gas uptake in hydrate phase. At the same time, the combination of TBAB and[C₈min] BF₄ could increase the mole friction of CH₄ in residual gas comparing with the data in THF solution. CH₄ separation efficiency was strongly enhanced. Since that the size of CO₂ and CH₄ molecules are similar, CH₄ and CO₂ could form the similar hydrate, so the recovery of CH₄ from biogas decreases lightly. The CH₄ content in biogas can purified from 67 mol% to 77 mol% after one-stage hydrate formation. In addition, the combination of THF and[C₈min] BF₄ do not have obvious promoting effect on CH₄ separation comparing with the gas separation results in pure THF solution.     

Tribological behavior of graphene nanoplatelet reinforced 3YTZP composites

The tribological behavior of graphene nanoplatelet (GNP) reinforced 3 mol% yttria tetragonal zirconia polycrystals (3YTZP) composites with different GNP content (2.5, 5 and 10 vol%) was analyzed and discussed. Their dry sliding behavior was studied using a ball-on-disk geometry with zirconia balls as counterparts, using loads between 2 and 20 N at ambient conditions and compared to the behavior of a monolithic 3YTZP ceramic used as a reference material. The composites showed lower friction coefficients and higher wear resistance than the monolithic 3YTZP. An outstanding performance was achieved at 10 N, where the friction coefficient decreased from 0.6 to 0.3 and the wear rates decreased 3 orders of magnitude in comparison with the monolithic ceramic. A layer adhered to the worn surface was found for all the composites, but it did not acted as a lubricating film. The composites with the lowest GNP content showed an overall improved tribological behavior.     

Characteristics and catalytic properties of Co/TiO2 for various rutile:anatase ratios

This present study revealed a dependence of rutile:anatase ratios in titania on the characteristics and catalytic properties of Co/TiO₂ catalysts during CO hydrogenation. In this study, Co/TiO₂ catalysts were prepared using various titania supports consisting of various rutile:anatase ratios of titania. In order to identify the characteristics, all catalyst materials were characterized using XRD, SEM/EDX, TPR, and hydrogen chemisorption. CO hydrogenation (H₂/CO = 10/1) was also performed to determine the overall activity and selectivity. It was found that both activity and selectivity were altered by changing the rutile:anatase ratios in the titania support.     

A new model for slab and beam structures––comparison with other models

In this paper an optimized model for the analysis of plates reinforced with beams is presented as compared with other models used by various researchers. The adopted model contrary to the models used previously takes into account the resulting inplane forces and deformations of the plate as well as the axial forces and deformations of the beams, due to combined response of the system. According to this model the stiffening beams of the structure are isolated from the plate by sections parallel to the lower outer surface of the plate. The forces at the interface, which produce lateral deflection and inplane deformation to the plate and lateral deflection and axial deformation to the beam, are established using continuity conditions at the interface. The adopted model describes better the actual response of the plate-beams system and permits the evaluation of the shear forces at the interface, the knowledge of which is very important in the design of composite or prefabricated ribbed plates. Four additional models neglecting the shear forces at the interfaces are presented and used for comparison reasons, while a three-dimensional elasticity model is also employed for the verification of the accuracy of the results of the examined models. The findings from this investigation, using the adopted model, which approximates better the actual response of the plate-beams system, necessitate the consideration of the inplane forces and deformations.     

基于Cohesive单元法的弃置井水泥塞-套管界面胶结失效数值模拟

水泥塞-套管界面胶结失效对弃置井井筒完整性提出了严峻挑战。考虑地下流体与水泥塞的流固耦合作用,基于cohesive单元方法,建立水泥塞-套管-水泥环-地层系统三维有限元模型,模拟垂直井水泥塞-套管界面裂缝剥离过程,研究地应力对界面裂缝损伤演化的影响,并分析水平地应力、水泥塞力学参数及界面性质对裂缝剥离高度的影响。结果显示:水平地应力均匀时剥离裂缝沿着整个界面圆周延伸且高度相等,水平地应力非均匀时剥离裂缝倾向于沿着界面某一圆周角扩展且在最大水平地应力方向具有较大的高度;水泥塞弹性模量从30 GPa减小到1 GPa,裂缝剥离高度降低9.3 m,临界法向强度从0.25 MPa增大到2.0 MPa,裂缝剥离高度降低6.5 m,表明较低的弹性模量及较大的临界法向强度有利于减小水泥塞-套管界面胶结失效的风险;水泥塞泊松比从0.35减小到0.10,裂缝剥离高度仅降低2.0 m,临界剪切强度从0.5 MPa增加到4.0 MPa,裂缝剥离高度仅降低3.3 m,表明泊松比和临界剪切强度对界面胶结失效影响较小。建立的模型能够为水泥浆配方优选和井筒弃置工艺优化提供指导。      

How did the price and income elasticities of natural gas demand in China evolve from 1999 to 2015? The role of natural gas price reform

As a cleaner, high-efficiency, and low-carbon fuel, natural gas has been an important fuel resource for China. To achieve a substantial increase in natural gas demand, China has sought to reform its natural gas pricing mechanism. Employing a set of unbalanced panel data for China’s 30 provinces covering 1999–2015, this study aims to estimate the evolving price and income elasticities of natural gas demand and explore the effect of natural gas price reform in China. For this purpose, a series of econometric techniques allowing for cross-sectional dependence and slope homogeneity is utilized. The results suggest that although natural gas demand in China still lacks negative price elasticity, the phenomenon is improving. Moreover, the estimates suggest that natural gas demand in China is indeed becoming increasingly sensitive to income changes. Our estimates also provide strong evidence in favor of the effect of natural gas price reform on the change in price elasticity as the price elasticity decreases in five of the seven regions. In addition, the results indicate large variations in the change in price and income elasticities of natural gas demand across China’s regions. Natural gas demand is becoming more price inelastic in Southwest China and Northwest China, while such demand in North China and East China responds less sensitively to income changes. These findings offer several policy suggestions for the reform of China’s natural gas market at the national and regional levels.     

TiO2反蛋白石结构膜材料改性及其光催化活性研究

利用液相沉积技术对TiO2反蛋白石结构材料进行表面处理,通过在反Opal孔内表面生成一层TiO2颗粒,增加其有效比表面积。以降解罗丹明B为探针反应,研究了经LPD表面处理之后的TiO2反Opal材料的光催化活性,考察了硼酸用量对TiO2反Opal材料表面形貌和光催化活性的影响。结果表明LPD处理之后的TiO2反Opal膜比未处理的膜具有更高的光催化活性,硼酸用量在0.0183 g/mL时处理的TiO2反Opal膜具有最高的光催化活性,相比未处理的膜催化剂活性提高了6倍。     

Energy efficiency improvement procedures and audit results of electrical,thermal and solar applications in Palestine

Energy conservation in utilities has played a vital role in improving energy efficiency in the industrial, commercial and residential sectors. The electrical energy consumption in Palestine has increased sharply in the past few years and achieved by the end of 2001 to 10% per year. It is expected that this percentage will increase to about 12% if the current political situation will end hopefully with peace. Modern energy efficient technologies are needed for the national energy policy. Such technologies are investigated in this paper. Implementing of a national 3 years project aiming at energy efficiency improvement in residential and industrial sectors as well as in public utilities, which include wide range of diversified audits and power measurements, had led to creating this paper. Measurement and audit results had shown that the total conservation potential in these sectors is around 15% of the total energy consumption. The associated costs of the investment in this field are relatively low and correspond to a pay back period varying in the range from 6 to 36 months. Consequently, the energy conservation policy will be seriously improved in the forthcoming years. It is estimated that 10% of the new energy purchasing capacity will be reduced accordingly.     

高温鼓泡床内气固两相流动的数值模拟

针对高温鼓泡床内的气固两相流动,在热态鼓泡床中试装置的基础上建立了鼓泡床物理模型,采用团聚曳力模型对高温鼓泡床内气固两相流动进行模拟研究。模拟结果表明,当颗粒当量直径为235μm时,模拟得到的床层密度与实验值吻合较好;随温度的升高,气固曳力增大,使得床层密度有所降低;对颗粒体积分数的概率分布及压力脉动方差的分析表明,随温度的升高,固相中的颗粒减少,而气相中的颗粒增多,同时气泡尺寸有所增大,床层气固两相运动更加剧烈。