Search Results (5)

Soil–rock mixtures pose significant challenges in mountainous regions due to their complex flow behavior and destructive potential during landslides and debris flows. Despite growing interest in using baffle arrays as protective measures, current research has focused on idealized soil or rock materials, leaving a notable gap in understanding their efficacy against heterogeneous soil–rock mixtures under varied slope and baffle configurations. This study employs the Material Point Method to simulate the continuum behavior of the soil matrix, while the Discrete Element Method (DEM) models the discrete dynamics of rock boulders. By incorporating Spheropolygon DEM, the model accurately captures complex soil–rock structure interactions. Parametric simulations are conducted to evaluate the effects of baffle location and slope angle on flow kinematics, impact forces, and energy dissipation. Results show that baffles placed closer to the structure significantly reduce downstream impact forces and kinetic energy by enhancing energy dissipation. Steeper slope angles result in increased impact forces on the structure due to greater conversion of potential energy to kinetic energy. The findings provide quantitative insights into optimizing baffle placement for improving infrastructure resilience against soil–rock mixture flows. Full article

Enhancing river passability is considered a central part of the efforts to maintain fish population and achieving good ecological status, according to the EU Water Framework Directive (WFD). One commonly proposed approach to achieving this aim involves the creation of fishways. However, recent studies have shown that many of these fish passes are often lacking an optimal design with far reaching consequences for fish migration. Several promising new designs such as nature-like rock ramps, with uphill flow, have been recently developed. Such studies attempt to address these drawbacks by adapting several structure-related features (i.e., boulder size and shape and friction walls). In this study, we used a 2D computational fluid dynamic model to assess how the key hydraulic variables (water depth, velocity and turbulent kinetic energy) were impacted by different design elements of uphill flow fishways with different configurations. With regard to the standard boulder shapes and sizes, our results reveal that: (1) doubling the boulder sizes results in a decrease of turbulent kinetic energy in resting corridors of up to 33%; (2) the inclusion of small friction-walls in the ramp design increases uphill velocity in the intermediate corridors by up to 49%; (3) the trapezoidal shape of the boulder leads to the largest decreases in maximum velocity in the gaps (16%) and the largest increases in the uphill velocity in the resting corridors (180%). These results may allow us to optimise the uphill flow rock-ramp design to improve the passability of this type of fishways. Full article

Occupant behavior can significantly influence the operation and performance of buildings. Many occupant-centric key performance indicators (KPIs) rely on having accurate counts of the number of occupants in a building, which is very different to how occupancy information is currently collected in the majority of buildings today. To address this gap, the authors develop a standardized methodology for the calculation of percent space utilization for buildings, which is formulated with respect to two prevalent operational data schemas: the Brick Schema and Project Haystack. The methodology is scalable across different levels of spatial granularity and irrespective of sensor placement. Moreover, the methods are intended to make use of typical occupancy sensors that capture presence level occupancy and not counts of people. Since occupant-hours is a preferable metric to use in KPI calculations, a method to convert between percent space utilization and occupant-hours using the design occupancy for a space is also developed. The methodology is demonstrated on a small commercial office space in Boulder, Colorado using data collected between June 2018 and February 2019. A multiple linear regression is performed that shows strong evidence for a relationship between building energy consumption and percent space utilization. Full article

Large boulders have been found in marine cliffs from 7 study sites on Ibiza and Formentera Islands (Balearic Islands, Western Mediterranean). These large boulders of up to 43 t are located on platforms that form the rocky coastline of Ibiza and Formentera, several tens of meters from the edge of the cliff, up to 11 m above sea level and several kilometers away from any inland escarpment. Despite than storm wave height and energy are higher from the northern direction, the largest boulders are located in the southern part of the islands. The boulders are located in the places where numerical models of tsunami simulation from submarine earthquakes on the North African coast predict tsunami impact on these two islands. According to radiocarbon data and rate of growth of dissolution pans, the ages of the boulders range between 1750 AD and 1870 AD. Documentary sources also confirm a huge tsunami affecting the SE coast of Majorca (the largest Balearic Island) in 1756. The distribution of the boulders sites along the islands, the direction of imbrication and the run-up necessary for their placement suggest that they were transported from northern African tsunami waves that hit the coastline of Ibiza and Formentera Islands. Full article

Low-head ramped weirs are a common instream obstacle to fish movements. Fish passability of these structures, where water passes over but does not generate a waterfall, is primarily related to ramp length and slope, but their relative contribution has seldom been considered. This study aims to assess the passage performance of a potamodromous cyprinid, the Iberian barbel (Luciobarbus bocagei), negotiating an experimental ramped weir with varying ramp length (L) and slope (S). Four configurations were tested, with a constant discharge of 110 L∙s⁻¹. Results suggest that both factors influenced passage performance of fish. Attraction efficiency (AE) increased with increasing L and S, whereas the number of successes (N) and passage efficiency (PE) decreased upon increasing L. For S, it was found that both N and PE peaked at the intermediate level (20%). These results suggest that configurations with the lowest slopes may not necessarily be the best option because they may be less attractive for the fish and their demand for space is higher. Higher slopes (but not excessive) could be more attractive to fish, less space-demanding, and therefore, more cost-effective. Future studies should investigate how discharge and boulder placement influence fish passage across ramped weirs, to improve habitat connectivity. Full article