Kinetic theory for strong uniform shear flow of granular media at high density

We discuss the uniform shear flow of a fluidized granular bed composed of monodisperse Hertzian spheres. Considering high densities around the glass transition density of inelastic Hertzian spheres, we report kinetic theory expressions for the Newtonian viscosity as well as the Bagnold coefficient. We discuss the dependence of the transport coefficients on density and coefficient of restitution.Comment: Powders & Grains 201

AN INFORMATION SYSTEM DESIGN THEORY FOR GREEN INFORMATION SYSTEMS FOR SUSTAINABILITY REPORTING - INTEGRATING THEORY WITH EVIDENCE FROM MULTIPLE CASE STUDIES

Du to increasingly noticeable environmental impacts of business activities and consequntly rising demands for environmental information by organizational stakeholders, reliable sustainability reporting (SR) is ever more important for firms. As the task of detailed sustainability reporting is complex and involves gathering and processing of a considerable amount of data, green information systems (Green IS) are seen as suitable to support this task. While some Green IS for SR are commercially available, their adoption is low. One reason is that there is a lack of knowledge of how to design these IS. This paper seeks to provide guidance for the design of Green IS for SR by suggesting an information system design theory (ISDT), which is a set of primarily prescriptive statements describing how to construct the class of Green IS for SR. Therefore, we synthesize knowledge gained from organizational and management theories with insights from 29 case studies conducted in a variety of industries. In result we derived a specific ISDT for Green IS for SR, that contributes to solve the trade-offs between environmental data transparency, complexity and data collection effort. Thus, the proposed ISDT paves the way for future improved Green IS for SR and sustainable development

Open Vehicular Data Interfaces for In-Car Context Inference

In this paper, we present a concept for an open vehicular data interface and describe it's components and architecture. We discuss the enabled applications in the context of advanced driver assistance systems with a focus on humanmachine interfaces, vehicle-to-x (V2X) communication and context inference systems. We conclude by a presentation of the initial implementation and deployed system

The manifold rheology of fluidized granular media

Fluidized granular media have a rich rheology: measuring shear stress $\sigma$ as a function of shear rate $\dot\gamma$, they exhibit Newtonian behavior $\sigma\sim\dot\gamma$ for low densities and shear rates, develop a yield stress for intermediate shear rates and densities approaching the granular glass transition, and finally, cross over to shear-thickening Bagnold scaling, $\sigma\sim\dot\gamma^2$. This wealth of flow-behaviors makes fluidized beds a fascinating material, but also one that is challenging to encompass into a global theory, despite its relevance for optimizing industrial processes and predicting natural hazards. We provide careful measurements spanning eight orders of magnitude in shear rate, and show that all these rheological regimes can be described qualitatively and quantitatively using the granular integration through transient formalism, a theory for glassy dynamics under shear adapted to granular fluids

Extending the Touchscreen Pattern Lock Mechanism with Duplicated and Temporal Codes

We investigate improvements to authentication on mobile touchscreen phones and present a novel extension to the widely used touchscreen pattern lock mechanism. Our solution allows including nodes in the grid multiple times, which enhances the resilience to smudge and other forms of attack. For example, for a smudge pattern covering 7 nodes, our approach increases the amount of possible lock patterns by a factor of 15 times. Our concept was implemented and evaluated in a laboratory user test (n = 36). The test participants found the usability of the proposed concept to be equal to that of the baseline pattern lock mechanism but considered it more secure. Our solution is fully backwards-compatible with the current baseline pattern lock mechanism, hence enabling easy adoption whilst providing higher security at a comparable level of usability

Text Entry Performance and Situation Awareness of a Joint Optical See-Through Head-Mounted Display and Smartphone System

Optical see-through head-mounted displays (OST HMDs) are a popular output medium for mobile Augmented Reality (AR) applications. To date, they lack efficient text entry techniques. Smartphones are a major text entry medium in mobile contexts but attentional demands can contribute to accidents while typing on the go. Mobile multi-display ecologies, such as combined OST HMD-smartphone systems, promise performance and situation awareness benefits over single-device use. We study the joint performance of text entry on mobile phones with text output on optical see-through head-mounted displays. A series of five experiments with a total of 86 participants indicate that, as of today, the challenges in such a joint interactive system outweigh the potential benefits.Comment: To appear in IEEE Transactions on Visualization and Computer Graphics On page(s): 1-17 Print ISSN: 1077-2626 Online ISSN: 1077-262