Experimental and numerical investigations on the heat production and thermal storage characteristics of rapid preparation amorphous powder activated coke

The heat production and thermal storage characteristics of rapid-preparation amorphous powder activated coke (RAC) were investigated. RAC was prepared by using a drop-tube reactor system. The natural oxidation characteristics of RAC were studied through combined TG–FTIR analysis and temperature-programmed experiment. Experimental results showed that CO and CO₂ were the main oxidation products of RAC in air, and that the oxidation reaction was in accordance with the Arrhenius equation and law of mass action. Thermal storage characteristics were studied through computational fluid dynamics simulation. The maximum excess temperature θ_max increases linearly with the increase of the initial temperature. The concentration fields of the products show that CO₂ is mainly concentrated in the upper part of the coke bin, and the CO generated by CO₂ at high temperature is mainly concentrated in the central part of the coke bin.     

Fabrication of NixCo3-xS4 hollow nanosphere as wideband electromagnetic absorber at thin matched thickness

Nowadays, transition metal sulfide (TMS), especially for spinel crystal structure (A_xB_3-xS₄), have been proved to be a promising electromagnetic (EM) absorber if been used to deal with the severe electromagnetic pollution. However, EM performance degradation and absorption layer thickness-decreasing at present remains a big challenge, owning to the poor EM attenuation ability. To overcome this barrier, herein we reported a Ni_xCo_3-xS₄ (x = 0, 0.3, 0.6, 1.0) absorber with hollow sphere structure to realize a good EM performance with a thinner matched thickness (<1.5 mm). The average sizes of these Ni_xCo_3-xS₄ distributed in 450–550 nm. The dielectric loss ability (ε'') can be boosted by tuning the molar ratio of Ni/Co, which attributes to EM performance. Additionally, hollow structure would lead to the electromagnetic multi-reflection, also benefited to EM performance. The results demonstrated that the maximum qualified absorption bandwidth (f_E) of 3.8 GHz can be achieved for the Ni_0·3Co_2·7S₄ sample when specimen thickness only equals to 1.3 mm.     

A highly active composite electrocatalyst Ni–Fe–P–Nb2O5/NF for overall water splitting

This work demonstrates a facile Nb₂O₅-decorated electrocatalyst to prepare cost-effective Ni–Fe–P–Nb₂O₅/NF and compared HER & OER performance in alkaline media. The prepared electrocatalyst presented an outstanding electrocatalytic performance towards hydrogen evolution reaction, which required a quite low overpotential of 39.05 mV at the current density of ?10 mA cm^?2 in 1 M KOH electrolyte. Moreover, the Ni–Fe–P–Nb₂O₅/NF catalyst also has excellent oxygen evolution efficiency, which needs only 322 mV to reach the current density of 50 mA cm^?2. Furthermore, its electrocatalytic performance towards overall water splitting worked as both cathode and anode achieved a quite low potential of 1.56 V (10 mA cm^?2).     

Cavern Boundary Determination with Pseudoplastic Fluid Based on the Apparent Viscosity Method

The cavern characteristics of xanthan gum solutions stirred by impellers of a perturbed six-bent-bladed turbine (6PBT) were investigated numerically using computational fluid dynamics (CFD) with laminar flow model. The apparent viscosity method was proposed to determine the boundary of the cavern. The cavern sizes predicted by apparent viscosity were in good agreement with the calculated results, and this method was not influenced by speed and impeller configuration. However, the predicted results of the cavern by the traditional speed method usually displayed a great deviation, especially at high speed. Therefore, it is feasible to determine the cavern boundary with the apparent viscosity, i.e., 0.25 times the yield viscosity of a pseudoplastic fluid, as the unified standard.     

A new method of predicting the saturation pressure of oil reservoir and its application

Saturation pressure is a vital parameter of oil reservoir which can reflect the oilfield characteristics and determine the oilfield development process, and it is determined by experiments in the laboratory in general. However, there was only one well with saturation pressure test in this target reservoir, and it is necessary to determine whether this parameter is right or not.In this work, we present a new method for quickly determining saturation pressure using machine learning algorithms, including random forest regressor (RF), support vector machine (SVM), decision trees (DT), and artificial neural network (ANN or NN). Using these approaches, saturation pressure was obtained by using the initial solution gas-oil ratio (GOR), temperature, API gravity and other reservoir-fluid data available in the oilfields. Compared with the empirical formula for saturation pressure calculation, the calculated result shows that the accuracy given from machine learning is higher than that from other formulas at home and abroad, and has a good match with the lab test. On the basis of the calculated saturation pressure, it can determine whether the reservoir enters into the stage of dissolved gas drive or not, which also provides the basis for maintaining the reservoir pressure by water injection in advance, rational development decision-making and work over measures.This approach above can provide technical guidance for predicting the saturation pressure in the development of different kinds of reservoirs, including the sandstone reservoirs and carbonate reservoirs.     

A note on stability analysis of 2-D linear discrete systems based on the Fornasini–Marchesini second model: Stability with asymmetric Lyapunov matrix

A recently reported Lyapunov based criterion (Singh (2014) [7]) for the asymptotic stability of two-dimensional (2-D) linear discrete systems described by the Fornasini–Marchesini second local state-space (FMSLSS) model is reviewed. It is established in this paper that, despite utilizing a more general Lyapunov matrix, Singh's criterion will never lead to an enhanced stability region in the parameter-space as compared to that obtainable via Hinamoto–Lu's criterion.     

跨境电商保税仓库拣货策略研究

针对跨境电商客户订单的多品类且数量不稳定的特点，对跨境电商保税仓库拣货流程进行分析与优化。采用订单动态时间窗分拣策略，并在仓库拣货路径优化的基础上，建立了跨境电商保税仓库拣货模型。最后应用于某公司跨境电商保税仓库管理系统中，取得了较好的预期效果。     

溶解氧变化对阴极极化下10Ni5CrMo钢氢脆敏感性的影响

摘要：为研究溶解氧质量浓度对10Ni5CrMo钢在阴极极化条件下氢脆敏感性影响规律，对10Ni5CrMo钢进行了阴极极化下的电化学交流阻抗谱测试﹑并采用慢应变速率拉伸实验和断口分析方法研究了海水中溶解氧质量浓度变化和不同阴极极化下10Ni5CrMo钢的氢脆敏感性。结果表明：溶解氧质量浓度变化对10Ni5CrMo钢强度几乎没有影响；同一溶解氧质量浓度下，随极化电位负移，断裂时间、伸长率、断面收缩率明显降低，氢脆系数增加，氢脆敏感性显著提高，极化电位达到-1000mV时，氢脆系数已超过安全区允许的最高值25%，进入危险区；同一极化电位下，随着海水中溶解氧质量浓度减少，材料塑性变差，断裂时间、伸长率和断面收缩率不断降低，氢脆系数增加，氢脆敏感性提高。     

场协同对PP/PS复合体系传热传质性能的影响

从动量和能量守恒方程出发,提出速度场与温度场的协同耦合作用对聚合物流动与换热具有重要影响,并以此为依据设计了新型扭转螺杆结构和场协同螺杆。以聚丙烯(PP)和聚苯乙烯(PS)为原料制备PP/PS复合材料体系,通过挤出试验对比研究了常规螺杆与场协同螺杆的传热传质性能。结果表明,相对于常规螺杆,设置有扭转螺杆结构的场协同螺杆的数均粒径更小、粒径分布密度和平均停留时间更大,提高了挤出机的混合能力;场协同螺杆的对流换热系数更大、径向温差更小,提高了挤出机的换热能力。     

沉浸式艺术审美体验的自我发现与再设计

探讨沉浸式艺术这一新概念，研究其审美体验是如何有助于自我发现并运用于艺术创作再设计中的。沉浸式艺术是一种能够启发感知联觉的审美体验方式，可使人们重新思考自己与“世界”(真实和虚拟)之间的关系。“感知”、“关系”和“转换”是三个相互交织并贯穿全文的主要问题，同时也是沉浸式艺术的研究基础。结合海德格尔“在世界上”(être-au-monde) 的观念来看，与其说“存在”，不如说人们沉浸并感知于这个世界中。然而，人们对周围环境的感知通常是无意识的，对于感知的认识也时常是冷漠和忽视的。沉浸式艺术使这些感觉得以被强调，它突出了个人的感知运动能力，同时也引起了人们对身体本身的重视。又如Bergson所提出的“投机性关注是建立在一种感知机制的基础上的，这种感知机制从根本上允许对世界进行一定行动而不是仅仅了解这个世界”。因此，对于一个完善的沉浸式审美体验过程来说，重要的是使观众自然地参与其中。当无意识的行为转换为肉眼可见的视觉效果时，审美体验将会更加深入人心。因此关于沉浸式艺术作品的创作，可以结合西方艺术家Marcel Duchamp的Ready-made的创作理念和中国道家的“无为”思想，研究怎样将被忽视的日常行为自然地转换为可见的，被重视的视觉效果，从而揭发主体与“世界”之间的多种潜在关系。