半干法烟气脱硫整体化模型

建立了半干法烟气脱硫整体化模型,通过模型分析确定了半干法烟气脱硫工艺各阶段的反应机理.结果表明:在脱硫塔内石灰浆滴干燥的常速阶段初期,控制脱硫反应的环节是石灰的溶解阻力;在常速阶段后期,反应过程由气膜扩散阻力控制;在降速阶段,限制脱硫反应进行的阻力是反应物向反应区域的扩散;在脱硫塔内干燥后阶段以及布袋除尘器中,气固反应的控制阻力是SO2通过脱硫产物层的扩散.模型计算结果与试验结果较吻合.

电网换相换流器整体化电磁暂态仿真模型及算法

现有的电磁暂态仿真算法能够准确刻画基于电网换相换流器的高压直流(LCC-HVDC)输电系统的运行特性,但计算量较大。为了提高LCC-HVDC输电系统的仿真效率,对现有常用的电网换相换流器电磁暂态仿真模型进行了简化,提出电网换相换流器整体化电磁暂态仿真模型与求解算法。整体化模型包含换流变压器与换流阀,换流变压器采用简化模型,换流阀采用理想开关模型,能够对换流器的电气网络结构进行简化。该算法将换流器电气网络拓扑结构分割为主网络与副网络,首先对主网络求解,然后根据得到的结果对副网络求解,最后更新当前仿真步长各换流阀的电流和电压。在PSModel仿真软件中对整体化电磁暂态仿真模型及算法进行了编程实现,并与PSCAD/EMTDC仿真结果进行对比,验证了其高效性与准确性。

林分生长和收获模型整体化思路探讨

介绍了林分生长和收获模型的概念、分类及模型整体化研究的内涵,以单木直径生长模型作为基础模型,提出了单木直径、树高、断面积、材积模型之间,林分平均直径、断面积、材积模型之间以及单木生长模型、全林分模型和径阶分布模型之间的耦合思路,对于解决不同水平模型之间的相容性、一致性及内部结构的统一具有一定意义.

学习拖延的整体化研究视角:传统与创新

传统的学习拖延是自我调节失败而导致非理性延迟的适应不良行为;最新研究提出了主动拖延的概念,认为主动拖延是自我调节的主动适应行为。根据学习拖延的定义及该领域的研究进展,将学习拖延分为三个阶段:传统学习拖延的多视角研究、传统学习拖延的自我调节研究、整体化观点的探索研究。文章依次介绍了每个阶段的研究成果。文章最后以自我调节机制为主线,整合了主动拖延和被动拖延,初步建立了一个拖延整体化模型。该模型的主要贡献在于,提出了干预被动拖延,促进主动拖延的有益于健康的整体化方案。

Global optimization for ducted coaxial-rotors aircraft based on Kriging model and improved particle swarm optimization algorithm

To improve the operational efficiency of global optimization in engineering, Kriging model was established to simplify the mathematical model for calculations. Ducted coaxial-rotors aircraft was taken as an example and Fluent software was applied to the virtual prototype simulations. Through simulation sample points, the total lift of the ducted coaxial-rotors aircraft was obtained. The Kriging model was then constructed, and the function was fitted. Improved particle swarm optimization(PSO) was also utilized for the global optimization of the Kriging model of the ducted coaxial-rotors aircraft for the determination of optimized global coordinates. Finally, the optimized results were simulated by Fluent. The results show that the Kriging model and the improved PSO algorithm significantly improve the lift performance of ducted coaxial-rotors aircraft and computer operational efficiency.

A risk-based methodology for the optimal placement of hazardous gas detectors

Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.

Pion Susceptibilities of the Vacuum in a Modified Global Colur Symmetry Model

Based on a modified version of the global color symmetry model,the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculated beyond the vacuum saturation approximation.Comparison with the previous estimations has been given.

Feasibility study on the integration of urban and rural minimum living security system based on SWOT model

This paper uses SWOT analysis, feasibility analysis of integration of urban and rural residents in China, including the overall analysis of the urban and rural integration China internal conditions, mainly for its overall advantages and disadvantages are analyzed; and the external environment, the system is mainly to raise the opportunities and threats were analyzed; in these. The external conditions are analyzed based on the construction of SWOT strategic matrix, found the advantages and disadvantages of the reform process of the integration of urban and rural subsistence allowances system in coexist, opportunities outweigh the challenges, so China＇s overall urban and rural integration construction is feasible.

Overall optimization of Rankine cycle system for waste heat recovery of heavy-duty vehicle diesel engines considering the cooling power consumption

The Rankine cycle system for waste heat recovery of heavy-duty vehicle diesel engines has been regarded as a promising tech- nique to reduce fuel consumption. Its heat dissipation in the condensation process, however, should be take：l away in time, which is an energy-consuming process. A fan-assisted auxiliary water-cooling system is employed in this paper. Results at 1300 r/min and 50% load indicate that the cooling pump and cooling fan together consume 7.66% of the recovered power. What＇s worse for the heavy load, cooling accessories may deplete of all the recovered power of the Rankine cycle system. Af- terwards, effects of the condensing pressure and water feeding temperature are investigated, based on which a cooling power consumption model is established. Finally, an overall efficiency optimization is conducted to balance the electric power gener- ation and cooling power consumption, taking condensing pressure, pressure ratio and exhaust bypass valve as major variables. The research suggests that the priority is to increase condensing pressure and open exhaust bypass valve appropriately at high speed and heavy load to reduce the cooling power consumption, while at low speed and light load, a lower condensing pressure is favored and the exhaust bypass valve should be closed making the waste heat recovered as much as possible. Within the sub-critical region, a larger pressure ratio yields higher overall efficiency improvement at medium-low speed and load. But the effects taper off at high speed and heavy load. For a given vehicular heavy-duty diesel engine, the overall e：＇ficiency can be improved by 3.37% at 1300 r/min and 25% load using a Rankine cycle system to recover exhaust energy. The improvement becomes smaller as engine speed and load become higher.