Centralized Coded Caching with User Cooperation

In this paper, we consider the coded-caching broadcast network with user cooperation, where a server connects with multiple users and the users can cooperate with each other through a cooperation network. We propose a centralized coded caching scheme based on a new deterministic placement strategy and a parallel delivery strategy. It is shown that the new scheme optimally allocate the communication loads on the server and users, obtaining cooperation gain and parallel gain that greatly reduces the transmission delay. Furthermore, we show that the number of users who parallelly send information should decrease when the users' caching size increases. In other words, letting more users parallelly send information could be harmful. Finally, we derive a constant multiplicative gap between the lower bound and upper bound on the transmission delay, which proves that our scheme is order optimal.Comment: 9 pages, submitted to ITW201

Impacts of cognitive factors on creativity quality in design: identification from performance in recall, association and combination

The reason why people have different creativity quality levels may depend on their different performances relating to other cognitive factors that are important for creativity. This study was designed to identify the performance of three cognitive factors (recall, association, and combination) that a designer may use in a creative process and then identify how the differing performance for these cognitive factors will affect creativity quality levels. Seventy-one participants were recruited to undertake a design task and complete a semi-structured interview. The results indicate that, in a creative design process, similar performances in recall, association, and combination can result in differences in creativity quality level

Influence of Dynamic River Stage on The Vulnerability of Water Wells and Structure Foundations in Cold Regions

Groundwater is important for people in Northern Canada, yet the groundwater protection protocols and water well vulnerability assessments designed for other warmer regions of Canada may not be applicable to communities in Northern Canada due to the unique hydrogeological characteristics there. The seasonal melt of snow and ice leads to intense river stage fluctuations and might cause flooding issues for the adjacent floodplain; however, their influences on the vulnerability of drinking water wells and nearby infrastructure are not fully understood. This research considers a case study at Carmacks, central Yukon, where an integrated surface-subsurface numerical modelling code was used to examine these processes. The model results indicate that the annual variation in the river stage temporarily reverses the direction of the hydraulic gradient between the surface water body and the adjacent aquifer. Stream reaches that gain groundwater under lower river stages can become losing streams during the high stage periods, which facilitates the transport of solute from the river to the adjacent aquifer. Additionally, the model shows that the annual river stage variation can temporarily alter the size and orientation of the region that contributes water to pumping wells, which means new environmental threats could become important. In terms of travel time, the model results suggest that annual river stage variation accelerates the transport of river-origin solutes to the adjacent aquifer, and higher river peaks facilitate more rapid solute migration. Thus, the natural protection of the soil travel path against microbial pathogens may become inefficient and water wells may become more vulnerable. The model results also demonstrate that higher peak river stages are more likely to cause basement inundation in buildings on the riverbank than average peaks, and that the duration of basement inundation varies at different locations

Simulating the friction between atomic layers by using a two-q model: Analysis of the relative motion and coherence

Studying friction between atomic layers is not only of great interest for the fundamental aspect of the tribology but also important for many applications such as the layer adhesion in wearable technologies and energy saving. The previous theoretical study has used the modified Prandtl-Tomlinson model to describe the motion of the tip above a two-dimensional atomic layer in an atomic force microscopy experiment. Here the degree of freedom for the substrate has been further explicitly included in the simulation, which is significant because the coherence between the sensing and the substrate layers can be explicitly addressed by computing their relative motion. For both layers, graphene has been chosen as an example for the simulations. Based on the simulations reported here, which agree with the previous relevant theoretical and atomic-force-microscopy experimental results, the motions between the sensing sheet and the substrate can be clearly distinguished. The dependence of motion and force on the parameters for the mechanical properties of the individual layers and the interaction potential between the layers has been carefully studied. For the relatively large values of the parameters for the mechanical properties, the relative motions between the sensing sheet and the substrate show that there would be coherence between the layers, which is beneficial for the adhesion between them. However, many other parameter spaces can be studied further in the future. Similar to the simulations of the motions of the atomic layers, the computed force of the atomic-force-microscopy tip can also indicate the stability of the layers. The theoretical work reported can be used to identify explicitly the relative motions between the sensing sheet and the substrate, providing a substantial improvement for the understanding of the friction between atomic layers. Moreover, in principles, the modeling methodology proposed can be generalized to describe any number of layers in the thin-film devices, by adding a q-parameter for each layer

Influence of dynamic river stage on the vulnerability of water wells and structure foundations in cold regions

This research was undertaken thanks, in part, with support from the Global Water Futures Program funded by the Canada First Research Excellence Fund (CFREF)Groundwater is important for people in Northern Canada, yet the groundwater protection protocols and water well vulnerability assessments designed for other warmer regions of Canada may not be applicable to communities in Northern Canada due to the unique hydrogeological characteristics there. The seasonal melt of snow and ice leads to intense river stage fluctuations and might cause flood issues to the adjacent floodplain; however, their influences on the vulnerability of drinking water wells and nearby infrastructure are not fully understood. This research considers a case study at Carmacks, central Yukon, where an integrated surface-subsurface numerical modelling code was used to examine these processes. The model results indicate that the annual variation in the river stage temporarily reverses the direction of the hydraulic gradient between the surface water body and the adjacent aquifer. Stream reaches that gain groundwater under lower river stages can become losing streams during the high stage periods, which facilitates the transport of solute from the river to the adjacent aquifer. Additionally, the model shows that the annual river stage variation can temporarily alter the size and orientation of the region that contributes water to pumping wells, which means new environmental threats could become important. In terms of travel time, the model results suggest that annual river stage variation accelerates the transport of river-origin solutes to the adjacent aquifer, and higher river peaks facilitate more rapid solute migration. Thus, the natural protection of the soil travel path against microbial pathogens may become inefficient and water wells may become more vulnerable. The model results also demonstrate that higher peak river stages are more likely to cause basement inundation at buildings on the riverbank than an average peaks, and that the duration of basement inundation varies at different locations.Engineering Research Council of Canada (NSERC) || Government of Yukon || Global Water Futures (Canada First Research Excellence Fund

On the Inherent Privacy Properties of Discrete Denoising Diffusion Models

Privacy concerns have led to a surge in the creation of synthetic datasets, with diffusion models emerging as a promising avenue. Although prior studies have performed empirical evaluations on these models, there has been a gap in providing a mathematical characterization of their privacy-preserving capabilities. To address this, we present the pioneering theoretical exploration of the privacy preservation inherent in discrete diffusion models (DDMs) for discrete dataset generation. Focusing on per-instance differential privacy (pDP), our framework elucidates the potential privacy leakage for each data point in a given training dataset, offering insights into data preprocessing to reduce privacy risks of the synthetic dataset generation via DDMs. Our bounds also show that training with $s$-sized data points leads to a surge in privacy leakage from $(\epsilon, \mathcal{O}(\frac{1}{s^2\epsilon}))$-pDP to $(\epsilon, \mathcal{O}(\frac{1}{s\epsilon}))$-pDP during the transition from the pure noise to the synthetic clean data phase, and a faster decay in diffusion coefficients amplifies the privacy guarantee. Finally, we empirically verify our theoretical findings on both synthetic and real-world datasets