基于分段副产物瞬时选择性的反应器网络综合     

胡仰栋  周勇  伍联营 《中国海洋大学学报(自然科学版)》2020,50(3):61-66

针对第三类反应体系的反应器网络综合问题,提出将串联反应以反应物到目的产物的反应步数为依据的新分段策略。通过比较不分段目的产物、不分段目的产物和中间产品、分段副产物和分段目的产物这四种不同的瞬时选择性,提出以分段副产物瞬时选择性为参数,以其对关键组分浓度或转化率的导数为依据选择各阶段最合适的反应器,以目的产物总选择性最大为目标采用遗传算法优化反应器网络。通过三个实例验证了本文所建立方法在解决复杂反应反应器网络综合问题的有效性,且本方法同样适用于简单反应体系。  相似文献   

Melt migration and melt-rock reaction in the Alpine-Apennine peridotites:Insights on mantle dynamics in extending lithosphere     

Elisabetta Rampone  Giulio Borghini  Valentin Basch 《地学前缘(英文版)》2020,11(1):151-166

The compositional variability of the lithospheric mantle at extensional settings is largely caused by the reactive percolation of uprising melts in the thermal boundary layer and in lithospheric environments.The Alpine-Apennine(A-A)ophiolites are predominantly constituted by mantle peridotites and are widely thought to represent analogs of the oceanic lithosphere formed at ocean/continent transition and slow-to ultraslow-spreading settings.Structural and geochemical studies on the A-A mantle peridotites have revealed that they preserve significant compositional and isotopic heterogeneity at variable scale,reflecting a long-lived multi-stage melt migration,intrusion and melt-rock interaction history,occurred at different lithospheric depths during progressive uplift.The A-A mantle peridotites thus constitute a unique window on mantle dynamics and lithosphere-asthenosphere interactions in very slow spreading environments.In this work,we review field,microstructural and chemical-isotopic evidence on the major stages of melt percolation and melt-rock interaction recorded by the A-A peridotites and discuss their consequences in creating chemical-isotopic heterogeneities at variable scales and enhancing weakening and deformation of the extending mantle.Focus will be on three most important stages:(i)old(pre-Jurassic)pyroxenite emplacement,and the significant isotopic modification induced in the host mantle by pyroxenite-derived melts,(ii)melt-peridotite interactions during Jurassic mantle exhumation,i.e.the open-system reactive porous flow at spinel facies depths causing bulk depletion(origin of reactive harzburgites and dunites),and the shallower melt impregnation which originated plagioclase-rich peridotites and an overall mantle refertilization.We infer that migrating melts largely originated as shallow,variably depleted,melt fractions,and acquired Si-rich composition by reactive dissolution of mantle pyroxenes during upward migration.Such melt-rock reaction processes share significant similarities with those documented in modern oceanic peridotites from slow-to ultraslow-spreading environments and track the progressive exhumation of large mantle sectors at shallow depths in oceanic settings where a thicker thermal boundary layer exists,as a consequence of slow-spreading rate.  相似文献   

A new numerical approach to the hyperstatic reaction method for segmental tunnel linings     

Ngoc Anh Do  Daniel Dias  Pierpaolo Oreste  Irini Djeran‐Maigre 《国际地质力学数值与分析法杂志》2014,38(15):1617-1632

This paper proposes a numerical approach to the hyperstatic reaction method (HRM) for the analysis of segmental tunnel linings. The influence of segmental joints has been considered directly using a fixity ratio that is determined on the basis of the rotational stiffness. The parameters necessary for the calculation are presented. A specific implementation has been developed using a FEM framework. This code is able to consider the three‐dimensional (3D) effect of segment joints in successive rings on the tunnel lining behaviour. The present HRM allows one to take an arbitrary distribution of segment joints along the tunnel boundary into consideration. In addition, the rotational stiffness of segment joints has been simulated using nonlinear behaviour, as it is closer to the true behaviour of a joint than linear or bilinear behaviour. The numerical results of three hypotheses on ring interaction, which allow the 3D effect of a segmental tunnel lining to be taken into account, have been compared with data obtained from the shield‐driven tunnel of the Bologna–Florence high‐speed railway line project. The numerical results presented in the paper show that the proposed HRM can be used to effectively estimate the behaviour of a segmental tunnel lining. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

基于非均质地层参数表征的颗粒流模型构建          下载免费PDF全文

夏余宏烨  孙平贺  伍新民  盛汉洋  王心龙  张绍和 《探矿工程》2021,48(S1):52-60

非均质地层参数的获取与表征方法是浅层地质体改造的重要依据。基于非均质地层的地质建模,表征具有随机不确定性和模糊不确定性的土体表观参数和物理力学参数。利用 Weibull 分布统计描述局部地层信息,并应用Diamond-Square分形插值方法,结合差分盒子维计算非均质地层分形维数,进一步合理演算整体地层参数。采用PFC3D数值模拟软件,结合马尔科夫链蒙特卡洛方法采样数据,对非均质地层块石颗粒及土颗粒进行建模。通过非均质地层模拟结果,发现其破坏过程与应力应变曲线要比均质土体复杂得多,由于块石大颗粒的含量、分布特性对土样力学性质影响显著。本文建模方法有助于非均质地层参数表征研究。  相似文献   

Estimation of turbulent sensible heat and momentum fluxes over a heterogeneous urban area using a large aperture scintillometer     

Sang-Hyun Lee  Jun-Ho Lee  Bo-Young Kim 《大气科学进展》2015,32(8):1092-1105

The accurate determination of surface-layer turbulent fluxes over urban areas is critical to understanding urban boundary layer (UBL) evolution. In this study, a remote-sensing technique using a large aperture scintillometer (LAS) was investigated to estimate surface-layer turbulent fluxes over a highly heterogeneous urban area. The LAS system, with an optical path length of 2.1 km, was deployed in an urban area characterized by a complicated land-use mix (residential houses, water body, bare ground, etc.). The turbulent sensible heat (Q H) and momentum fluxes (τ) were estimated from the scintillation measurements obtained from the LAS system during the cold season. Three-dimensional LAS footprint modeling was introduced to identify the source areas ("footprint") of the estimated turbulent fluxes. The analysis results showed that the LAS-derived turbulent fluxes for the highly heterogeneous urban area revealed reasonable temporal variation during daytime on clear days, in comparison to the land-surface process-resolving numerical modeling. A series of sensitivity tests indicated that the overall uncertainty in the LAS-derived daytime Q H was within 20%-30% in terms of the influence of input parameters and the non-dimensional similarity function for the temperature structure function parameter, while the estimation errors in τ were less sensitive to the factors of influence, except aerodynamic roughness length. The 3D LAS footprint modeling characterized the source areas of the LAS-derived turbulent fluxes in the heterogeneous urban area, revealing that the representative spatial scales of the LAS system deployed with the 2.1 km optical path distance ranged from 0.2 to 2 km2 (a "micro-α scale"), depending on local meteorological conditions.  相似文献   

Predicting size effect on diffusion-limited current density of oxygen reduction by copper wire     

芦永红  徐海波  王佳  钟莲 《中国海洋湖沼学报》2011,29(1)

The size effect of copper wire radius (0.04–0.82 mm) on the diffusion-limited current density of an oxygen reduction reaction in stagnant simulated seawater (naturally aerated 0.5 mol/L NaCl) is investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and compared with the results obtained in 0.5 mol/L H2SO4. In the oxygen diffusion-limited range, size effect is found to occur independent of electrolytes, which is attributed to non-linear diffusion. Additionally, to sati...  相似文献   

凹凸棒石与Zn^2＋的长期作用研究   总被引：1，自引：0，他引：1  

谢晶晶  陈天虎  王健  谢巧勤  刘海波 《矿物学报》2011,31(4):738-741

以凹凸棒石与Zn2＋为例研究粘土矿物与重金属离子长期作用过程,并运用高分辨透射电镜和X射线衍射分析粘土矿物与重金属离子长期作用的次生物相。结果表明：Zn2＋与凹凸棒石的长期作用是一个二阶段的过程,初始阶段为快速吸附作用,其后表现为慢速沉淀反应。高分辨透射电镜和X射线衍射分析表明,凹凸棒石与Zn2＋的长期作用过程中,具有纳米矿物特性的凹凸棒石表面快速水化,提高了悬浮液的pH值,诱导Zn2＋水解沉淀。而后,凹凸棒石缓慢溶解释放Al3＋和SiO44-与Zn（OH）2沉淀反应,形成Zn-A1双氢氧化物和异极矿。这一结果对认识土壤环境中重金属与粘土矿物的作用及重金属的归宿具有重要意义。  相似文献   

顾及外拓扑的异构建筑三维拓扑重建   总被引：2，自引：1，他引：1  

贺彪  李霖  郭仁忠  史云飞 《武汉大学学报(信息科学版)》2011,(5):579-583

分析了异构建筑在三维拓扑重建中的问题,依据拓扑数据模型的需求,提出了基于顶图、底图和结构图的自动拓扑重建算法,该算法能够有效地对异构建筑进行整体三维拓扑重建,不仅保留了建筑内每一实体单元的内拓扑,同时也兼顾了实体间的外拓扑。基于该方法,设计并开发了三维地籍管理系统中的数据生成模块,以深圳市某小区为实验区,验证了算法的可行性及有效性。  相似文献   

多源异构日志综合分析技术研究与实践     

刘必雄 《南京气象学院学报》2011,(4):365-370

多源异构日志分析技术是目前国内外网络安全领域的研究热点.首先,提出了一种包括聚焦分析、统计分析和因果关联分析在内的多源异构日志综合分析模型,引入重要度评价方法对日志信息进行聚焦分析,并通过实例加以说明;然后探讨了多源日志因果关联分析算法;最后利用网络实例数据,对所提出的综合分析模型和算法进行了验证.结果表明该模型和算法是可行的和有效的.  相似文献   

异质性农户土地流转的决定性因素与政策建议     

张淑萍 《地域研究与开发》2015,(4)

建立异质性农户土地流转行为的理论分析基础,利用Logistic回归分析方法和河南省调查数据,明确农户土地流转决策的影响因素。研究结果表明:农村信贷市场约束是纯农户、以农业收入为主的农户转入土地的需求不足的重要原因;规避就业风险和争夺土地租金是非农户和以非农业收入为主的农户转出土地的供给不足的主要原因;土地控制权偏好与生存预期造成中年、老年农户竭力排斥土地流转;农村土地流转不活跃的决定性因素是国家保护农业与有效管理兼业农户、非农户的责任缺位。  相似文献