An experimental investigation of the force network ensemble

We present an experiment in which a horizontal quasi-2D granular system with a fixed neighbor network is cyclically compressed and decompressed over 1000 cycles. We remove basal friction by floating the particles on a thin air cushion, so that particles only interact in-plane. As expected for a granular system, the applied load is not distributed uniformly, but is instead concentrated in force chains which form a network throughout the system. To visualize the structure of these networks, we use particles made from photoelastic material. The experimental setup and a new data-processing pipeline allow us to map out the evolution subject to the cyclic compressions. We characterize several statistical properties of the packing, including the probability density function of the contact force, and compare them with theoretical and numerical predictions from the force network ensemble theory.Comment: accepted for publication in the conference proceedings of Powders and Grains 201

Protocol-Dependence and State Variables in the Force-Moment Ensemble

Stress-based ensembles incorporating temperature-like variables have been proposed as a route to an equation of state for granular materials. To test the efficacy of this approach, we perform experiments on a two-dimensional photoelastic granular system under three loading conditions: uniaxial compression, biaxial compression, and simple shear. From the interparticle forces, we find that the distributions of the normal component of the coarse-grained force-moment tensor are exponential-tailed, while the deviatoric component is Gaussian-distributed. This implies that the correct stress-based statistical mechanics conserves both the force-moment tensor and the Maxwell-Cremona force-tiling area. As such, two variables of state arise: the tensorial angoricity ($\hat{\alpha}$) and a new temperature-like quantity associated with the force-tile area which we name {\it keramicity} ($\kappa$). Each quantity is observed to be inversely proportional to the global confining pressure; however only $\kappa$ exhibits the protocol-independence expected of a state variable, while $\hat{\alpha}$ behaves as a variable of process

Digital Sludging in the Privacy Context: Evidence of a Multigroup Analysis

Organizations apply aggressive tactics to harvest and exhaust data from individuals. These tactics exploit human psychology to manipulate individuals’ behavior through user interface design characteristics. Because governmental regulations for data collection were introduced recently, organizations make use of digital sludging to prevent individuals from refusing the consent for the data collection – most commonly within the cookie consent. Digital sludging is characterized as excessive and unjustified frictions that increase the effort and decrease the attention of a specific choice. Hence, we conducted a vignette study to investigate digital sludging in the privacy context further. Overall, we contribute to existing research by demonstrating how privacy concerns affect the perception and interaction with the cookie consent. In addition, we outline how manipulative practices such as digital sludging influence individuals’ decision-making

Examining the Use of Blockchain Technology in Virtual Worlds: A Socio-Technical Systems Perspective

Recent developments, including the rebranding of Facebook to Meta, have led to large-scale media attention on the phenomenon of the Metaverse. Although not being a new phenomenon in Information Systems (IS) research, many intricacies in virtual worlds remain unexplored. In particular , prior research has directed attention to users‘ lack of ownership rights, creating tension between the creator and user. To solve this tension, we argue that blockchain technology can potentially help to structure ownership rights. Therefore, our research explores a blockchain-based Metaverse through the socio-technical system lens. Our study highlights that, in the underlying case, the use of blockchain technology goes beyond the application of Non- Fungible Tokens (NFTs) and can also be found in the general organizational structure, blurring the boundaries of existing stakeholders. Our work contributes to research by providing a gaze into blockchain-based Metaverses and highlighting the potential application and benefit of the technology in virtual worlds