Direct shear behavior of gravel-rubber mixtures: Discrete element modeling and microscopic investigations

In this paper, a newly developed 3-dimentional discrete element model (DEM) for gravel-rubber mixtures (GRMs), namely DEM4GRM, that is capable of accurately describing the macro-scale shear response (from small to large deformation) of GRMs in a direct shear box apparatus is presented. Rigid gravel grains are modelled as simple multi-shape clumps, while soft rubber particles are modeled by using deformable 35-ball body-centered-cubic clusters. Mixtures are prepared with different volumetric rubber content (VRC) at 0, 10, 25, 40 and 100%, statically compressed under 30, 60 and 100 kPa vertical stress and then sheared, by closely simulating a reference laboratory test procedure. The variation of micro-scale factors such as fabric, normal and tangential force anisotropy is carefully examined throughout the shearing process and described by means of novel micro-mechanical relationships valid for GRMs. Moreover, strong-force chains are scrutinized to identify the transition from rigid to soft granular skeleton and gain insights on the load transfer and deformation mechanisms of GRMs. It is shown that the development of the fabric and force anisotropy during shearing is closely related to the macro-scale shear strength of GRMs, and strongly depends on the VRC. Besides, strong-force chains appear to be primarily formed by gravel-gravel contacts (resulting in a rigid-like mechanical behavior) up to VRC = 30%, and by rubber-rubber contacts (causing a soft-like mechanical response) beyond VRC = 60%. Alternatively, at 30% < VRC < 60%, gravel-rubber contacts are predominant in the strong-force network and an intermediate mechanical behavior is observed. This is consistent with the behavioral trends observed in the macro- and micro-mechanical responses.     

Understanding the asymmetric perceptions of smartphone security from security feature perspective: A comparative study

Smartphones are being used and relied on by people more than ever before. The open connectivity brings with it great convenience and leads to a variety of risks that cannot be overlooked. Smartphone vendors, security policy designers, and security application providers have put a variety of practical efforts to secure smartphones, and researchers have conducted extensive research on threat sources, security techniques, and user security behaviors. Regrettably, smartphone users do not pay enough attention to mobile security, making many efforts futile. This study identifies this gap between technology affordance and user requirements, and attempts to investigate the asymmetric perceptions toward security features between developers and users, between users and users, as well as between different security features. These asymmetric perceptions include perceptions of quality, perceptions of importance, and perceptions of satisfaction. After scoping the range of smartphone security features, this study conducts an improved Kano-based method and exhaustively analyzes the 245 collected samples using correspondence analysis and importance satisfaction analysis. The 14 security features of the smartphone are divided into four Kano quality types and the perceived quality differences between developers and users are compared. Correspondence analysis is utilized to capture the relationship between the perceived importance of security features across different groups of respondents, and results of importance-satisfaction analysis provide the basis for the developmental path and resource reallocation strategy of security features. This article offers new insights for researchers as well as practitioners of smartphone security.     

Multiple material domain‐based computational tools for ease assessment of modal parameter in photonic crystal fibers

We report here the development of two computational tools PCFPS (Photonic Crystal Fiber Parameter Study) and PCFPA (Photonic Crystal Fiber Parameter Analysis), equipped with graphical user interface (GUI) for modeling of photonic crystal fiber. The tools are based on different structural parameters, and they provide characteristic analysis of the modal parameters from the structural parameters. The main feature of PCFPS is that it enables the user to find out the values of each defining modal parameter that has an immense contribution towards the manufacture of photonic crystal fiber. Additionally, PCFPA allows the user to observe the variation in the modal parameters with respect to the changes in structural parameters (such as d, Λ, d/Λ, and λ/>Λ). Besides their ease of use, these two schemes have high computational precision and adaptability, giving a novel platform to optical engineers to modulate the microstructured fibers according to their requirement.     

Alkylated indolo[3,2,1-jk]carbazoles as new building blocks for solution processable organic electronics

A facile strategy for the introduction of tert-butyl and hexyl chains to the indolo[3,2,1-jk]carbazole scaffold is presented. With these building blocks six materials based on three different 4,4′-bis(N-carbazolyl)-1,1-biphenyl derivatives with varying degree of planarization were prepared. Characterization of the materials showed that the alkyl chains have only minor effects on the photophysical properties of the compounds. In contrast, thermal robustness towards decomposition and electrochemical stability are increased by the introduced alkyl chains. Detailed investigation of the solubility in five different solvents revealed that the incorporation of the alkyl chains increases the solubility significantly. The increased solubility of the materials allowed the application as host materials in red, green and sky-blue solution processed phosphorescent organic light emitting diodes. Hence, this work presents the first solution processed light emitting devices based on the indolo[3,2,1-jk]carbazole scaffold.     

Relationships among boredom proneness,sensation seeking and smartphone addiction among Chinese college students: Mediating roles of pastime,flow experience and self-regulation

Smartphones are indispensable for many young people, which in turn increases the risk of smartphone addiction. Previous studies have discovered significant and positive influences of boredom proneness, sensation seeking and smartphone addiction. This study further explored these influences, their underlying mechanisms, and the mediating effects of pastime, flow experience and self-regulation on smartphone addiction. A total of 442 Chinese college students completed a survey focusing on boredom proneness, sensation seeking, pastime, flow experience, self-regulation and smartphone addiction. The results indicated that boredom proneness positively affects smartphone addiction. Contrary to expectations, the results showed that there is no significant relationship between sensation seeking and smartphone addiction. Moreover, pastime and self-regulation have partial mediation effects on the relationship between boredom proneness and smartphone addiction, while the effect of sensation seeking on smartphone addiction is completely transmitted with the help of flow experience and self-regulation. The findings and their implications are discussed.     

Relevance- and interface-driven clustering for visual information retrieval

Search results of spatio-temporal data are often displayed on a map, but when the number of matching search results is large, it can be time-consuming to individually examine all results, even when using methods such as filtered search to narrow the content focus. This suggests the need to aggregate results via a clustering method. However, standard unsupervised clustering algorithms like $K$-means (i) ignore relevance scores that can help with the extraction of highly relevant clusters, and (ii) do not necessarily optimize search results for purposes of visual presentation. In this article, we address both deficiencies by framing the clustering problem for search-driven user interfaces in a novel optimization framework that (i) aims to maximize the relevance of aggregated content according to cluster-based extensions of standard information retrieval metrics and (ii) defines clusters via constraints that naturally reflect interface-driven desiderata of spatial, temporal, and keyword coherence that do not require complex ad-hoc distance metric specifications as in $K$-means. After comparatively benchmarking algorithmic variants of our proposed approach – RadiCAL – in offline experiments, we undertake a user study with 24 subjects to evaluate whether RadiCAL improves human performance on visual search tasks in comparison to $K$-means clustering and a filtered search baseline. Our results show that (a) our binary partitioning search (BPS) variant of RadiCAL is fast, near-optimal, and extracts higher-relevance clusters than $K$-means, and (b) clusters optimized via RadiCAL result in faster search task completion with higher accuracy while requiring a minimum workload leading to high effectiveness, efficiency, and user satisfaction among alternatives.     

Nature inspired supply chain solutions: definitions,analogies, and future research directions

ABSTRACT

Supply chains are becoming increasingly complex, and many companies and researchers are looking to nature for finding solutions. In this paper, we provide a narrative synthesis and systematic review to explore state-of-the-art, and identify key areas for exploration of nature inspired solutions in the supply chain area. We consider strategic, tactical, and operational decisions within supply chains and identify analogies between biological systems and supply chains to create a new research agenda. Our findings show that the majority of the research in nature inspired supply chains from the systemic perspective focuses on closed loop supply chains. In contrast, similar systemic solutions such as industrial symbiosis, circular economy, and industrial ecology have not been explored as frequently. Reducing production waste (industrial symbiosis) in addition to end-of-life product waste (closed loop supply chains), optimising raw material use and extending the life of used resources (circular economy), investigating the interactions between biosphere and technosphere (industrial ecology), and seeking solutions to industrial problems from nature (biomimicry) are all possible paths for reaching a zero-waste economy. These systemic solutions have a considerable impact on the supply chains at the strategic, tactical, and operational levels, which need to be explored to identify efficient and effective solutions.     

Turbulent times: tourists’ attitudes towards wind turbines in the Southern Highlands in Iceland

As a response to the threat of climate change, many nations are increasing their use of renewable energy, including wind energy. Large wind farms often conflict with other land uses, particularly tourism, which is a growing industry worldwide. In Iceland, tourism has recently become the largest export sector, with majority of tourists travelling to the country to experience its nature. This paper examines tourists’ opinions and perceptions of wind power development in the Southern Highlands of Iceland and compares how number, size and proximity of wind turbines, and the landscape in which they are situated, influence tourists’ perceptions. The study is based on an on-site questionnaire survey conducted in 2015. The results indicate that one-third of the travellers would be less likely to visit the Southern Highlands if a proposed wind farm were built, and two-thirds think that wind turbines would decrease the area’s attractiveness.     

基于危险源的水利工程施工全过程安全管理研究

水利工程的特殊性,决定了其在安全管理构建中更加注重全过程管理机制的构建,以及危险源下的精准安全管控。在传统安全管理模式之下,水利工程安全管理盲点多、效率低,不利于全过程安全管理的高效实施。文章立足水利工程的危险辨识,分析了水利工程危险源全过程安全管理中的问题,并在此基础之上,从强化危险源精准辨识、构建危险源动态管理机制、优化危险源评价工作、加快危险源信息库建设等方面,具体论述了危险源下水利工程全过程安全管理措施。     

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。