A contact model for rough crushable sand

Sand roughness is now accessible to measurement. Incorporating this parameter into sand models using the discrete element method (DEM) is known to improve bulk small strain response. In this work we explore the effect on problems where particle crushing takes place. A well-established DEM particle crushing model and a rough Hertzian contact model are here combined to incorporate both effects in a single contact model. Including contact roughness results in stronger particles whilst all other material parameters being equal. The model is then used to simulate high pressure oedometric compression tests on a strong silica sand. It is shown that including realistic values of surface roughness enables to correctly capture both load-unload behaviour and particle size distribution evolution while using realistic values of elastic bulk properties for the sand grains. Roughness is then a model refinement that may result in simpler, more objective DEM calibrations.     

新一代信息基础设施推动能源发展的路径安排和绩效研究

随着信息技术的迅猛发展,其带来的变革浪潮涌动在各个角落。作为社会的运行动脉,能源的产生运转和利用体系享受新一代信息基础设施的优势,发生着巨大变化。文章研究了新一代信息基础设施对于能源革命的推动传导方式的影响,分析了在这一过程中新一代信息基础设施普及对能源行业及能源使用方式的影响。基于过往信息化数据、已有理论及当下流行的5G运用方式,做回溯性探究,前瞻未来能源革命的蓝图。     

基于聚集诱导发光效应的高固低黏丙烯酸荧光树脂的制备及其性能研究

为了研制一种具有荧光功能特性的高固低黏羟基丙烯酸树脂。从聚集诱导发光效应（AIE）出发，将具有 AIE性质的二对丙烯酸四苯乙烯酯荧光分子通过自由基共聚连接于聚合物链段。由于聚合物链段对荧光分子化学键固定以及聚合物链的包裹束缚作用，导致荧光分子运动受限，从而实现涂层在紫外灯下荧光发光。通过荧光光谱的实时跟踪，探索高固低黏羟基丙烯酸树脂的合成以及固化规律。此外，由于聚合物链段对外界刺激具有实时响应性，从而间接影响了所连接的荧光分子的荧光发光行为。因此，文中也探索了涂层在外界温度与化学气体的影响下所发生的荧光变化的规律，以探索其在功能涂层中应用的可行性。     

钛合金铣削加工表面残余应力有限元仿真

为了分析铣削工艺参数对钛合金已加工表面残余应力的影响,根据金属切削有限元分析的相关理论,以钛合金Ti6Al4V为工件材料,建立了铣削加工的有限元模型。采用正交试验设计法对钛合金Ti6Al4V铣削仿真的工艺参数进行优化,并用极差法分析不同的铣削速度、铣削深度、铣削路径对钛合金Ti6Al4V工已加工表面残余应力的影响。研究表明:在钛合金Ti6Al4V铣削过程中,对工件已加工表面残余应力影响因素由小到大依次为:铣削深度<铣削路径<铣削速度,切削深度对已加工表面残余应力影响较小,铣削速度对已加工表面残余应力影响最大;在研究范围内,随着铣削速度的增大,已加工表面残余应力逐渐增加。     

球头铣刀铣削球面的表面形貌建模与仿真研究

基于齐次坐标矩阵变换原理和矢量运算法则，建立了工件坐标系下球头铣刀扫掠面的数学模型，基于Z-MAP法设计了球形表面形貌的生成算法，利用该算法对球头铣刀分别采用3D环绕法和放射加工法这两种典型走刀路线加工凸球面，并对加工后的表面形貌进行了仿真，通过分析对比仿真结果，发现3D环绕法更有利于减小表面粗糙度。同时，仿真结果和试验结果具有较高的吻合度，表明该仿真方法是可靠的，可以用于实际生产中球头铣刀铣削球面表面形貌的预测。     

How to perform and report an impactful analysis using partial least squares: Guidelines for confirmatory and explanatory IS research

Partial least squares path modeling (PLS-PM) is an estimator that has found widespread application for causal information systems (IS) research. Recently, the method has been subject to many improvements, such as consistent PLS (PLSc) for latent variable models, a bootstrap-based test for overall model fit, and the heterotrait-to-monotrait ratio of correlations for assessing discriminant validity. Scholars who would like to rigorously apply PLS-PM need updated guidelines for its use. This paper explains how to perform and report empirical analyses using PLS-PM including the latest enhancements, and illustrates its application with a fictive example on business value of social media.     

A skeletal n-butane mechanism with integrated simplification method

A new skeletal mechanism of n-butane is developed for describing its ignition and combustion characteristics applicable over a wide range of conditions: initial temperature 690–1430 K, pressure 1–30 atm, and equivalence ratio 0.5–2.0. Starting with a detailed chemical reaction kinetic model of 230 species and 1328 reactions (Healy et al., Combust. Flame, 2010), the directed relation graph method is applied as the first step to derive a semi-detailed mechanism with 134 species. Then, the reaction path analysis in conjunction with temperature sensitivity analysis is used to remove the redundant species and reaction paths simultaneously under the condition of low-temperature and moderate-to-high temperatures, respectively. Finally, a skeletal n-butane mechanism consisting of 86 species and 373 reactions can be obtained. Mechanism validation indicates that the new developed skeletal mechanism is in good agreement with the detailed mechanism in predicting the global ignition and combustion characteristics. The new skeletal mechanism is further validated using extensive available literature data including rapid pressure machine ignition delay time, shock-tube ignition delay time, laminar flame speed, and jet-stirred reaction oxidation, covering a large range of temperatures, pressures, and equivalence ratios. The comparison results demonstrate that a satisfactory agreement between predictions and experimental measurements is achieved.     

Restoration and functionality assessment of a community subjected to tornado hazard

The loss of infrastructure functionality for a community from a tornado can significantly affect economic vitality and result in substantial social disruption. The duration of the loss of functionality is a decisive factor in the magnitude of the economic disruption caused by a tornado. Therefore, quantitative models for the post-tornado restoration processes are needed in order to provide risk-informed decision support. In this study, the water network, electric power network, school buildings, residential buildings and businesses were modelled with their relative spatial distribution along with select dependencies and cross-dependencies in order to investigate the restoration of a community in the aftermath of a disaster. A tornado path was simulated using statistics from a historical tornado database. Based on the damage level of the components and their connectivity throughout the community, the functionality of the supplier nodes was assessed through a Monte Carlo simulation. Finally, the repair time of the damaged components was modelled to capture how the demands may be satisfied over time until eventually full restoration is achieved. Then, two metrics were defined to highlight business and social disruption following a tornado. The approach presented herein can be implemented in future studies to quantify indirect economic loss and social disruption resulting from a tornado.     

人工智能在智慧海洋建设中的应用

围绕人工智能与智慧海洋建设这条主线，论述人工智能、智慧海洋的概念，列举当前较为成熟的人工智能与海洋科技在海洋观测方面融合的切入点，初步展现一种海洋技术与装备智能化的发展路径，提出加快人工智能技术向智慧海洋建设赋能的几点建议。