稀土含量对喷熔层组织及耐蚀性的影响

本文通过在镍基自熔合金粉末中加入不同含量的稀土，研究了稀土含量对喷熔层组织及耐蚀性的影响规律及其作用机制。结果表明，在喷熔材料中加入适量稀土，可使喷熔层组织细化、晶界净化，从而使腐蚀过程中的表面活性点减少，耐蚀性提高。     

Computational Parametric Analysis of Cellular Solids with the Miura-Ori Metamaterial Geometry under Quasistatic Compressive Loads

Origami-based metamaterials have widespread application prospects in various industries including aerospace, automotive, flexible electronics, and civil engineering structures. Among the wide range of origami patterns, the fourfold tessellation known as Miura-ori is of particular attraction to engineers and designers. More specifically, researchers have proposed different 3D structures and metamaterials based on the geometric characteristics of this classic origami pattern. Herein, a computational modeling approach for the design and evaluation of 3D cellular solids with the Miura-ori metamaterial geometry which can be of zero or nonzero thicknesses is presented. To this end, first, a range of design alternatives generated based on a numerical parametric model is designed. Next, their mechanical properties and failure behavior under quasistatic axial compressive loads along three perpendicular directions are analyzed. Then, the effects of various geometric parameters on their energy absorption behavior under compression in the most appropriate direction are investigated. The findings of this study provide a basis for future experimental investigations and the potential application of such cellular solids for energy-absorbing purposes.     

Mathematical Modeling of Coke Formation and Deposition due to Thermal Cracking of Petroleum Fluids

A two‐dimensional mathematical dynamics model is presented to predict coke formation due to thermal cracking inside the tubes of fired heaters on two types of petroleum fluid. The laminar and turbulent flows are analyzed for both petroleum fluids. The second‐order k‐? standard model is adopted to make this mathematical model more accurate than previous models of coke formation. The radial and axial variations for temperature, velocity, and concentration due to the high temperature gradients inside the tubes are considered in the model equations. The finite volume method is the numerical model used to discretize the conservation equations. The proposed model is suitable to predict coke formation inside heater tubes since it indicates operational conditions where coke formation is minimized.     

OpenGL在煤矿液压支架四连杆机构运动仿真中的应用

基于OpenGL,通过建立液压支架的层次细节,运用反向动力学和运动学反解法原理,解决了液压支架四连杆机构运动仿真的问题。仿真结果表明,这一方法能比较真实、实时地模拟四连杆运动的关系,反映液压支架操作的基本动作,为综采工艺仿真系统的进一步研究提供了一种行之有效的方法和手段。     

Soft computing methodologies for estimation of energy consumption in buildings with different envelope parameters

In this study, soft computing methods are designed and adapted to estimate energy consumption of the building according to main building envelope parameters such as material thicknesses and insulation K-value. In order to predict the building energy consumption, novel intelligent soft computing schemes, support vector regression (SVR), and adaptive neuro-fuzzy inference system (ANFIS) are used. The polynomial, linear, and radial basis function (RBF) is applied as the kernel function of the SVR to estimate the optimal energy consumption of buildings. The performance of proposed optimizers is confirmed by simulation results. The SVR results are compared with the ANFIS, artificial neural network (ANN), and genetic programming (GP) results. The computational results show that an improvement in predictive accuracy and capability of generalization can be achieved by the ANFIS approach in comparison to the SVR estimation. Based on the simulation results, the effectiveness of the proposed optimization strategies is verified. The data used in soft computing were obtained from 180 simulations in EnergyPlus for variations of building envelope parameters.     

Landscape practice in the Middle East between local and global aspirations

In the Middle East today, there are strong tensions between global and local aspirations in landscape architectural projects. Modernism, introduced to major cities in the Middle East, led to design approaches that are detached from local context, some adopting a tabula rasa attitude to site or inspired by Western models with little adaptation. Ambitious designers who seek to celebrate local values through context-based designs face dilemmas between client-driven global aspirations and local contextual particularities. This perspective essay critically reviews landscape design approaches in the region against discourses of Modernism, regionalism and critical regionalism. Projects in Abu Dhabi, Dubai, Riyadh and Muscat were examined to provide a spectrum of current trends in landscape practices. Insights gained show that valuing intangible cultural meanings attached to landscapes, acknowledging particular ecological processes and working within the profound connections between culture and ecology, are critical to inform future design strategies.     

鼓泡塔中的有效涡扩散系数及湍流特性

依据湍流模式理论提出新的有效涡扩散系数关系式,讨论其与既有关系式的异同并与湍流实测数据比较,结果表明,本文关系式给出与实测值更为一致的结果,而既有的一些关系式的计算值偏高．由此讨论了涡扩散系数与鼓泡塔流动模型的关系,指出了数据偏差产生的原因．     

Fried egg digest decreases blood pressure in spontaneous hypertensive rats

Our previous study showed that in vitro simulated gastrointestinal digestion of fried whole egg (FWE) released several peptides with angiotensin converting enzyme-I (ACE-I) inhibitory properties. The present study evaluated in vivo blood pressure lowering effect of FWE digest in spontaneously hypertensive rats (SHR). Twelve to fourteen weeks old male SHRs were surgically implanted with telemetric blood pressure (BP) measuring devices. After one week recovery, animals were randomly allocated to three groups at dosage of FWE digest 0 (control), 100, and 1000 mg of FWE digest/kg body weight for 3 days (n = 8), and the BP was recorded continuously. The 1000 mg/kg BW group showed a significant decrease in BP and also rectified the impaired circadian blood pressure rhythm compared to the control group. This study indicates a potential blood pressure lowering effect of egg consumption.     

Kernel analysis on Grassmann manifolds for action recognition

Modelling video sequences by subspaces has recently shown promise for recognising human actions. Subspaces are able to accommodate the effects of various image variations and can capture the dynamic properties of actions. Subspaces form a non-Euclidean and curved Riemannian manifold known as a Grassmann manifold. Inference on manifold spaces usually is achieved by embedding the manifolds in higher dimensional Euclidean spaces. In this paper, we instead propose to embed the Grassmann manifolds into reproducing kernel Hilbert spaces and then tackle the problem of discriminant analysis on such manifolds. To achieve efficient machinery, we propose graph-based local discriminant analysis that utilises within-class and between-class similarity graphs to characterise intra-class compactness and inter-class separability, respectively. Experiments on KTH, UCF Sports, and Ballet datasets show that the proposed approach obtains marked improvements in discrimination accuracy in comparison to several state-of-the-art methods, such as the kernel version of affine hull image-set distance, tensor canonical correlation analysis, spatial-temporal words and hierarchy of discriminative space-time neighbourhood features.     

APPLICATION OF GENETIC NEURAL NETWORK IN Zn-27 % Al-Mg ALLOY

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