Within the realm of mixed reality, the capability to dynamically render environmental effects with high realism plays a crucial role in amplifying user engagement and interaction. Fluid dynamics, in particular, stand out as essential elements for crafting immersive virtual settings. This includes the simulation of phenomena like smoke, fire, and clouds, which are instrumental in enriching the virtual experience. This work showcases a cutting-edge system developed to produce dynamic and interactive fluid effects that mirror real captured data in real-time for mixed reality applications. This innovative system seamlessly incorporates fluid reconstruction alongside velocity estimation processes within the Unity engine environment. Our approach leverages a novel physics-based differentiable rendering technique, grounded in the principles of light transport in participating media, to simulate the intricate behaviors of fluid while ensuring high fidelity in visual appearance. To further enhance realism, we have expanded our framework to include the estimation of velocity fields, addressing the critical need for fluid motion simulation. The practical application of these techniques demonstrates the system's capacity to offer a robust platform for fluid modeling in mixed reality environments. Through extensive evaluations, we illustrate the effectiveness of our approach in various scenes, underscoring its potential to transform mixed reality content creation by providing developers with the tools to incorporate highly realistic and interactive fluid seamlessly.

Inverter-based resources (IBRs) such as photovoltaic systems and wind farms are being integrated into the power grids as part of climate change efforts. Most renewable resources utilize phase-locked loop (PLL) to establish network synchronization, and operate under the grid-following (GFL) mode. However, it has been recently reported that with the increasing amount of IBRs to replace fossil-fuel based synchronous generators, the continued use of GFL will reduce the overall stability of the grid. This issue can be resolved by changing the control mode of some inverters to grid-forming (GFM), which the PLL loop is replaced by a droop control loop. Nevertheless, the question regarding the ratio of operating IBRs under GFL and GFM in maintaining system stability has yet to be answered. This paper aims to fill this gap. We first built a high-fidelity simulation model consisting of only GFM and GFL inverters followed by extracting the stability features from the time-domain current and frequency waveforms of individual inverters. Next, an entropy weight method (EWM) is proposed to build an objective evaluation model for assessing the grid stability. Numerical studies were conducted to assess the stability due to different ratios of GFL and GFM along with different grid topologies and IBR locations. Overall, this paper serves as a guide for future placement strategies of distributed renewables within power grids.

The realistic interaction with physical phenomena is a crucial aspect of human-computer interaction (HCI) in virtual reality (VR). However, the real-time performance of physical simulation, interactive computation, and rendering is the bottleneck of physics-based VR HCI. To address these challenges, we propose a novel physics-oriented framework for multi-material objects and free-hand interaction, termed PhyVR. This framework enables users to interact with diverse virtual phenomena dynamically. At the algorithm level, we develop a unified particle system to describe both the virtual multi-materials and the user’s avatar for the efficiency issue, optimize collision detection, and accelerate the HCI algorithms with a variable fine-coarse particle sampling scheme. At the rendering level, we introduce a hybrid particle-grid anisotropic algorithm for surface reconstruction, enabling real-time and visually convincing fluid rendering. Comprehensive experiments and user studies demonstrate that our framework effectively captures various physical interaction phenomena, providing an enhanced user experience and paving the way for expanding VR-related HCI applications.