意向性、绝对流与先验现象学

由于错失了对实项被体验内容的生成和显现方式的彻底追问,现象学在立义意向的根基处隐含了不可知论。经过现象学还原,意向性在作为立义意向之根基的绝对流的意向作用的流形体中,逐步展示为能意-所意的先天流形、习性以及本能的意向流形,而先验现象学也相应地在纯粹的、习性的以及本能的意向流形的维度中得到了展示。

考虑损耗优化的多电平铁路功率调节器的混合环流注入策略

铁路功率调节器(railwaypowerconditioner,RPC)主要承担电气化铁路牵引系统的有功转移和无功、负序补偿。在V/v牵引系统中,多电平铁路功率调节器(multilevel railway power conditioner,MRPC)需补偿无功维持电网电压平衡,此时造成MRPC链节功率不平衡,导致链节间电容电压的发散。为抑制电压发散,需注入环流电压和电流。传统注入方案仅注入直流或交流分量,未考虑MRPC功率损耗等性能。针对应用于V/v牵引系统的MRPC,分析其等效电路模型和链节功率不平衡原因;建立MRPC功率损耗模型,提出优化MRPC功率损耗的混合环流注入策略,并以损耗优化为目标,对环流的幅值和初相角进行优化设计。通过仿真对所提出的混合环流注入策略与传统方案进行对比,验证所提方案的正确性和有效性。

CFD Simulation of Flow and Mass Transfer in Structured Packing Distillation Columns

Detailed investigation of flow behavior in structured packing distillation columns is of great importance in accurate prediction of process efficiency and development of more efficient and optimal equipment internals. In this study, a three-dimensional two-phase flow model based on VOF method for simulating the hydrodynamics and mass-transfer behavior in a typical representative unit of the structured packing is developed. In the proposed model, the c 2 - ε c model is used for the closure of turbulent mass transfer equation. By solving the proposed model, the velocity distribution, phase fraction profile and concentration field are obtained. Using these data, the total liquid holdup, the wetted area and the separation efficiency [height equivalent to a theoretical plate (HETP)] are estimated. For testing the model validation, the simulated HETPs are compared with our previous experimental data obtained in a 150 mm-diameter column containing Mellapak 350Y operating at the pressures of 0.6-1.8 MPa. The compari-son shows that they are in satisfactory agreement, with an average absolute deviation (AAD) of 25.4%.

Absolute geostrophic currents in global tropical oceans

A set of absolute geostrophic current(AGC) data for the period January 2004 to December 2012 are calculated using the P-vector method based on monthly gridded Argo profi les in the world tropical oceans. The AGCs agree well with altimeter geostrophic currents, Ocean Surface Current Analysis-Real time currents, and moored current-meter measurements at 10-m depth, based on which the classical Sverdrup circulation theory is evaluated. Calculations have shown that errors of wind stress calculation, AGC transport, and depth ranges of vertical integration cannot explain non-Sverdrup transport, which is mainly in the subtropical western ocean basins and equatorial currents near the Equator in each ocean basin(except the North Indian Ocean, where the circulation is dominated by monsoons). The identifi ed nonSverdrup transport is thereby robust and attributed to the joint effect of baroclinicity and relief of the bottom(JEBAR) and mesoscale eddy nonlinearity.

Heat and salt transport throughout the North Pacific Ocean

Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport(MHT) and meridional salt transport(MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents(WBCs) are estimated for the fi rst time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacifi c. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area.

Numerical Study of Natural Convection on Horizontal Strips Embedded in an Vertical Adiabatic Substrate

A full solution of two-dimensional Navier-Stokes and energy equation was conducted numerically to analyze the natural convection of the horizontal strip with an adiabatic substrate. The main features of such convection are: (i) the leading and trailing edge effect, (ii) the non-boundary layer effect, and (iii) the side edge effect. The results are compared with the boundary layer theory and experimental data.