Effect of droplet characteristics on heat transfer of mist/air cooling in a pin-finned channel

Effects of droplet characteristics of mist/air cooling on heat transfer for three pin-fin structures are investigated. The round-tip pin-fin structure is newly proposed with partial detachment from one endwall with a round-shaped tip structure. A flat-tip pin-fin with partial detachment and a traditional pin-fin with full attachment serve as references. Reynolds-averaged Navier-Stokes equations and the shear-stress-transport turbulence model are applied. Influences of initial mist temperature, initial mist diameter and initial mist velocity are analyzed in the Reynolds number range 15,000 to 50,000. The round-tip pin-finned channel has highest heat transfer coefficient and lowest pressure loss among the structures. Heat transfer enhancement increases first gradually and then decreases sharply with increasing initial mist diameter but an optimal diameter exists for the highest Nusselt numbers. Nusselt number decreases monotonically with increasing initial mist temperature. Droplet movement and heat transfer are nearly independent of initial mist velocity.     

A discontinuous least-squares finite-element method for second-order elliptic equations

In this paper, a discontinuous least-squares (DLS) finite-element method is introduced. The novelty of this work is twofold, to develop a DLS formulation that works for general polytopal meshes and to provide rigorous error analysis for it. This new method provides accurate approximations for both the primal and the flux variables. We obtain optimal-order error estimates for both the primal and the flux variables. Numerical examples are tested for polynomials up to degree 4 on non-triangular meshes, i.e. on rectangular and hexagonal meshes.     

Residual attention convolutional autoencoder for feature learning and fault detection in nonlinear industrial processes

Neural Computing and Applications - Deep learning has been successfully applied in process monitoring in recent years due to its powerful feature extraction. However, these monitoring methods are...     

Water Oxidation Catalysts for Artificial Photosynthesis

Water oxidation is the primary reaction of both natural and artificial photosynthesis. Developing active and robust water oxidation catalysts (WOCs) is the key to constructing efficient artificial photosynthesis systems, but it is still facing enormous challenges in both fundamental and applied aspects. Here, the recent developments in molecular catalysts and heterogeneous nanoparticle catalysts are reviewed with special emphasis on biomimetic catalysts and the integration of WOCs into artificial photosystems. The highly efficient artificial photosynthesis depends largely on active WOCs integrated into light harvesting materials via rational interface engineering based on in‐depth understanding of charge dynamics and the reaction mechanism.     

绿色建筑与防水之道

绿色建筑不是一种刻板的技术标准,而是一种理念,它与2500多年前老子的"天人合一"、"道法自然"的哲学思想是一胍相承的。通过《防水之道非常道》一诗的解析,就当前全面开展绿色建筑行动中的防水问题提出了看法与建议。     

Microcracks size growth prediction based on microdefects nucleation number

The mechanical reason for rock and concrete failure is trans-scale fracture, which can be divided into three phases: (1) microcrack evolution, (2) macrocrack nucleation, (3) macrocrack growth and run-through. Using the idea that a microcrack could be regarded as a well-organized aggregation of nucleated microdefects, the size growth model of the largest microcrack based on the accumulated number of microdefect nucleation is established. In order to test the validity of the model, trans-scale fracture of a plate made of heterogeneous material is numerically simulated to display the microcrack’s evolution. Statistical analysis of the number and sizes of the microcracks indicates that the predicted size of the largest microcrack according to the model is in close agreement with the measured crack size prior to peak stress, but not at all close to the measured values after the peak. At the end of the paper, some remaining problems are proposed for the further work.     

Microstructure and tensile properties of low cost titanium alloys at different cooling rate

Titanium and titanium alloys have several advantages, but the cost of titanium alloys is very expensive compared with the traditional metal materials. This article introduces two new low-cost titanium alloys Ti-2.1Cr-1.3Fe (TCF alloy) and Ti-3Al-2.1Cr-1.3Fe (TACF alloy). In this study, we used Cr-Fe master alloy as one of the raw materials to develop the two new alloys. We introduce the microstructure and tensile properties of the two new alloys from β solution treated with different cooling methods. Optica...     

A set‐membership approach to integrated trade‐off design of robust fault detection system

In order to improve fault detection (FD) performance, integrated design of residual generation and evaluation is investigated in this paper for trade‐offs between fault detection rate and false alarm rate (FAR). A set‐membership approach is proposed in residual evaluation by adopting a threshold ellipsoid, which enables more design freedom than a conventional threshold value. With the set‐based definitions of fault detection rate and FAR, the integrated design problem is formulated by maximizing the FD performance under a predefined FAR. The joint optimal selection of a residual generator and a threshold ellipsoid is equivalently transformed into a simplified optimization problem of determining an optimal threshold ellipsoid for any given residual generator. A suboptimal solution for the set‐membership‐based integrated FD system design is obtained based on approximated computation of the FD performance. Monte Carlo simulations show the performance improvement of the proposed method compared with an existing integrated design method. Copyright © 2016 John Wiley & Sons, Ltd.