Parameter and state estimation of kinetic and nonlinear dynamic systems

This paper presents a theoretical method for characterizing kinetic and dynamic systems. In this method the time courses of a system variables are approximated by linear combination of Legendre polynomials, and the least-squares criterion is used to find out the unknmown time courses and system parameters. The theory has been implemented by an algorithm which is described and its utility is illustrated by application to the kinetic system P + Q ⇄ PQ → Q + R.     

变压力梯度下钻井环空压力预测

为准确掌握变压力梯度钻井环空温度和压力分布特性,基于井筒流体流动与传热理论,充分考虑分离器位置处流体"变质量"传热传质与循环流体物性参数随温度和压力的变化,建立了变压力梯度下钻井环空温度和压力预测模型,并应用双循环迭代算法对模型进行求解,开展了环空温度和压力分布数值模拟研究。研究结果表明:相比于常规钻井,变压力梯度钻井环空温度和压力分布曲线上均存在一个明显拐点,且拐点位置与分离器位置一致;由于具有低导热系数空心球的注入,变压力梯度钻井环空流体温度要低于常规钻井;分离器位置、分离效率、空心球注入体积分数和空心球密度等参数均对变压力梯度钻井环空压力分布有较大影响。     

空间信息隐形搜索引擎研究

基于三层B/S结构,结合鼠标屏幕取词、快速中文地名识别和网络地图服务技术,设计并实现了一个空间信息隐形搜索引擎,实现即时、隐性的空间信息（文字和图形）动态获取。该引擎扩展了地理信息系统的应用模式,为空间信息服务提供了一种全新的技术。     

铁磁材料摩擦过程中磁化效应机制研究

为探究摩擦过程中磁记忆效应产生机制,采用Bitter粉纹法对摩擦过程中摩擦接触区域的磁畴组织进行原位观测,测量不同摩擦次数及不同摩擦载荷下磨痕表面的磁场变化以及摩擦影响区域内磁畴组织的时效变化。实验结果表明:摩擦过程中磨痕表面的磁场经历剧烈增加、缓慢增加到稳定变化3个阶段;摩擦接触区域内的畴壁在摩擦过程中转向垂直于往复摩擦方向,畴壁厚度和间距增加,畴壁的形态呈现弯曲状,且摩擦载荷为40 N时畴壁的这些变化比载荷为20 N时更加明显;摩擦后的磁畴组织发生时效变化,在静置60天后接触区域内畴壁变化后的状态开始消散,摩擦载荷为40 N时消散程度较20 N时小。     

Photovoltaic project investment based on the real options method: An analysis of the East China power grid region

Distributed photovoltaics (PV) play a key role in the energy transition. We construct an investment value and timing assessment model based on the real options method to improve scientific decision-making in distributed PV investing in an uncertain environment. The model is applied to analyze projects in the East China Power Grid region under multiple self-consumption ratio scenarios. The results show that investing in distributed PV projects is beneficial, but there are differences in the optimal investment timing under different self-consumption ratios. Investors can defer investment for as early as one year to obtain optimal investment value.     

Effects of ellipsoidal and regular hexahedral particles on the performance of the waste heat recovery equipment in a methanol reforming hydrogen production system

Hydrogen production from methanol has attracted attention due to its wide range of raw material sources and mature technology. Using waste heat of industrial high temperature solid particles like blast slag and steel slag etc. To provide vaporization heat and reaction heat for the reaction between methanol and water is an emerging technology for hydrogen production from methanol, which can save additional thermal energy resources. Herein, the performances of equipment that uses the waste heat of ellipsoidal and regular hexahedral particles to provide a heat source for methanol to hydrogen were explored by the DEM-CFD method. Compared with spherical particles of the same equivalent diameter, ellipsoidal and regular hexahedral particles have poor fluidity in the stagnant area, and the empty area is enlarged and irregular in shape. The average velocity peaks of the ellipsoidal and regular hexahedron particles are larger than those of spherical particles, and the overall mean velocity fluctuation of ellipsoidal particles is similar to that of spherical particles while the regular hexahedron particles' is larger. The average temperature drop rate of the ellipsoidal and regular hexahedral particles is slower than that of spherical particles, the uniformity of temperature distribution is worse than that of spherical particles. The ellipsoidal and regular hexahedral particles’ average effective heat transfer coefficient is smaller than that of spherical particles, and the heat transfer effect is weaker than that of spherical particles. The effective heat transfer coefficient of ellipsoidal particles is 2.95 W/(m⁻²∙K⁻¹) lower than that of spherical particles and the effective heat transfer coefficient of hexahedral particles is 6.09 W/(m⁻²∙K⁻¹) lower than that of spherical particles. Therefore, compared with the spherical particles of the same equivalent diameter, ellipsoidal and regular hexahedral particles produce less hydrogen.     

Highly homogeneous multicomponent mesoporous catalysts: Defective amorphous vs. nanocrystalline CeO2 structure towards CO-PROX reaction

Mesoporous multicomponent materials with uniform pore sizes and well-defined network geometries are viewed as highly attractive candidates in the catalysis field. However, their synthesis at a high homogeneity level is considered quite challenging. Herein, alumina based mixed oxides (Al/Ce/Cu or Fe) are produced through a facile evaporation-induced-self-assembly route and tested towards preferential oxidation of CO in H₂-rich gas. The effect of several synthetic parameters is investigated, with citric acid addition identified as a key factor in view of obtaining high mesoscopic order and notable homogeneity, particularly at high dopant amounts. Following thermal aging at 900 °C, metal oxides distribution and nanoporous nature are well-preserved with a parallel nucleation of ceria nanoparticles into the semi-crystalline inorganic framework. CO-PROX assessment of the aged samples reveals a drastic enhancement in catalytic activity, especially for the ternary Cu–Ce–Al system, associated with material's structural reconstruction strongly affecting metal–support interaction.     

Wettability and wettability modification methods of porous transport layer in polymer electrolyte membrane electrolysis cells (PEMEC): A review

As a key component of polymer electrolyte membrane electrolysis cells (PEMEC), the wettability of anode porous transport layer (APTL) plays an important role on the transport of gas and liquid water in the anode. This paper reviews the research progress on the materials, structural parameters and wettability of APTL, and discusses qualitatively the effect of wettability on the detachment characteristics of oxygen bubbles which are on the surface or in the internal pore channels of APTL by establishing force models of an oxygen bubble. For the surface wettability modification of titanium (Ti) fiber-based APTL, the feasibility of four surface chemical modification methods, namely silane coupling agent modification, dopamine (DA) modification, grafting modification based on Ultraviolet (UV) irradiation or supercritical fluid technology are analyzed, which makes up for the blank of review articles in this field. Finally, the above-mentioned chemical modification methods are possible research opportunities for the wettability transformation of APTL.     

Electrostatics of granules and granular flows: A review

In past decades, the electrostatics of granules and granular flows has obtained more and more attention due to many industrial problems and the associated development of new technologies. Granule-wall collision causes electrification, where charge transfer can be characterized by work function, electron transfer, ion transfer, and material transfer. Electrification is affected by many factors and increases with granule processing, and the charge amount can reach a saturated state where electrification no longer increases, which has been confirmed by single granule and granule conveying systems. In addition, the presence of electrostatic charges has profound influences in relevant areas, including chemistry, chemical engineering, energy, pharmaceuticals, and so on. The measurement technology of electrostatics used in granule conveying systems has been improved with the continuous progress of industry. Furthermore, electrostatics of granules and granular flows will be developed into a more accurate area together with other subjects as an interdisciplinary problem to be concerned. In addition, in the pneumatic conveying system, granule-wall and granule-granule collision or friction can cause material transfer due to material breakage. The working mechanism of the material transfer due to collision or friction has never been fully understood. Such problems will be solved gradually in the future.