Yidong Xia

Phase behavior of hydrocarbons in nanosized porous media is important for understanding fluid behavior in confined environments, yet direct experimental validation under elevated-pressure conditions remains limited. In this work, elevated-pressure differential scanning calorimetry (DSC) was used to measure boiling points of n-heptane and toluene confined in well-defined mesoporous silica materials (SBA-15 and SBA-16) at pressures up to 1300 kPa. The experimentally derived vapor pressure curves show a systematic suppression relative to bulk fluids across all pressures. Kelvin equation predictions and Gibbs Ensemble Monte Carlo (GEMC) simulations provide thermodynamic and qualitative molecular-level support for the observed confinement-induced phase behavior. In contrast, shale samples with low pore volumes and broader, more heterogeneous pore structures did not show a distinct confinement peak under the present experimental conditions. These findings provide elevated-pressure experimental data for confinement-induced phase behavior in well-defined mesoporous model systems and offer a benchmark for comparison with thermodynamic models and molecular simulations.

Reliable feeding of high-moisture lignocellulosic biomass is important for continuous thermo-chemical and hydrothermal conversion. Compression-screw feeders create pressure-sealing plugs, but the same compaction can change the delivered moisture state and increase drive load. This study combines pilot-scale experiments in a Chemical Preprocessing System(CPS) feeder withtwo plug-pipe lengths and a draining screw press operated over several backpressure setpoints with dry-contact discrete element method (DEM) simulations of confinement-driven solid-contact behavior.Feedstocks entered at approximately 50–58%wet-basis moisture, and outlet samples rangedfrom approximately 25–60%. Outlet material was frequently drier, particularly from the screwpress. Moisture-content reduction tended to be larger with the longer CPS plugpipe (𝜌=0.44,𝑛=51) and with increasing screw-press backpressure setpoint (𝜌=0.50, 𝑛=74). Drive-systemtorque also co-varied positively with moisture-content reduction within each platform, although the scatter was substantial. These associations are descriptive because the sampling was unbalanced, expressed liquid was not systematically measured, and repeated records shared material and operating history.Dry-contact DEM reproduced selected qualitative ordering with CPS confinement and particlesize and showed that stronger outlet constraint could increase the model-defined wall-normal contact-stress index. Absolute torque comparison was not supported because the simulations and experiments differed in shaft speed and torque definition, and the model omitted liquid, drainage, moisture-dependent contacts, and particle deformation. The results support dry-contact DEM as a qualitative screening tool for confinement-driven solid-contact trends, while predictive wet-biomass feeder design will require hydro-mechanical physics and speed-and throughput-matched validation data.

This paper introduces the overall design plan, development timeline, and preliminary progress of the Autonomous Pit Exploration System project. This project aims to develop an advanced multi-robot system for the efficient inspection of nuclear waste-storage tank pits. The project is structured into three phases: Phase 1 involves data collection and interface definition in collaboration with Hanford Site experts and university partners, focusing on tank riser geometry and hardware solutions. Phase 2 includes the selection of sensors and robot components, detailed mechanical design, and prototyping. Phase 3 integrates all components into a cohesive system managed by a master control package which also incorporates digital twin and surrogate models, and culminates in comprehensive testing and validation at a simulated tank pit at the Idaho National Laboratory. Additionally, the system’s communication design ensures coordinated operation through shared data, power, and control signals. For transportation and deployment, an electric vehicle (EV) is chosen to support the system for a full 10 h shift with better regulatory compliance for field deployment. A telescopic arm design is selected for its simple configuration and superior reach capability and controllability. Preliminary testing utilizes an educational robot to demonstrate the feasibility of splitting computational tasks between edge and cloud computers. Successful simultaneous localization and mapping (SLAM) tasks validate our distributed computing approach. More design considerations are also discussed, including radiation hardness assurance, SLAM performance, software transferability, and digital twinning strategies.