Search Results (1,206)

The Iberian barbel (Luciobarbus bocagei Steindachner, 1864) is a potamodromous species that displays migratory movements, with adults moving upstream during spring to spawn, followed by downstream migration in autumn by both adults and juveniles to feed and inhabit more productive river stretches. Increasing river fragmentation due to dam construction and operation causes a loss of connectivity and suitable habitat, which can affect this natural behaviour. In a tributary of River Douro, River Tua, a 108 m high dam, was recently built (i.e., Foz Tua dam in 2017) at only 1.1 km from the river mouth, leaving the upstream spawning area inaccessible. To evaluate the species behavioural response to this impact, a passive acoustic telemetry array was deployed in the study area, and between 2018 and 2023, 120 tagged fish had their movements tracked. The results showed two different behavioural profiles in the same population with migratory (42.5%) and resident (54.0%) individuals. During this period, a specific experimental study was developed to evaluate the response of a subset of 90 fish, captured upstream of the Foz Tua dam and translocated to an alternative downstream Douro tributary (River Pinhão, ~20 km downstream from River Tua). From these, 66.7% remained at the release site, whilst 23.3% returned to the river of origin, i.e., River Tua. From the returned fraction, 28.6% of the tagged fish maintained this migratory behaviour between both rivers in the following years. Generalized Additive Models were used for each of the two behavioural profiles observed in this study, to identify which environmental variables were associated with the presence of the tagged barbels downstream the Foz Tua dam. Ecological flow, temperature and day-period were some of the predictors explaining the use of this river stretch downstream of Foz Tua dam. This study substantially updates the available information regarding this species’ movement patterns at large spatial and temporal scales, contributing to enhancement of management and conservation programs for potamodromous species, in highly impounded and fragmented rivers. Full article

This study investigates the influence of PLA flowability and talc content on the performance of compostable thermoplastic starch/poly(butylene succinate) (TPS/PBS)-based systems for rigid applications. Different PLA grades with varying melt flow index (PLA23, PLA8 and PLA70) and talc contents (0, 5 and 10 wt%) were incorporated. Twelve formulations were compounded by twin-screw extrusion and processed by injection moulding. FTIR confirmed the coexistence of TPS, PBS and PLA phases without evidence of chemical interactions. Morphological analysis showed that PLA flowability plays a key role in phase distribution, with higher-flow PLA promoting improved dispersion and interfacial adhesion, while talc addition (5 and 10 wt%) increased structural heterogeneity; at higher loadings, particularly, DSC analysis revealed that talc acted as a nucleating agent for the PBS phase, increasing crystallisation temperatures from approximately 73 °C to 81 °C depending on formulation. Mechanical results showed that Young’s modulus increased from approximately 1.4 GPa to 2.7 GPa with decreasing PLA flowability and increasing talc content. Formulations containing low-flow PLA reached tensile strengths close to 32 MPa, although elongation at break decreased to values near 2%. In contrast, high-flow PLA formulations exhibited a more balanced mechanical response, with elongation values up to approximately 8%, associated with improved phase dispersion. Hybrid PLA systems showed intermediate behaviour, reaching elongations up to 22% while maintaining modulus values around 1.8 GPa. Talc provided additional reinforcement but reduced deformation capacity. HDT values remained relatively constant, indicating limited improvement in thermomechanical resistance despite increased stiffness. These results demonstrate that the combined control of PLA molecular characteristics and talc content enables tuning of the mechanical and thermomechanical performance of TPS/PBS/PLA/talc systems for rigid packaging applications. Full article

This study presents a transient computational fluid dynamics (CFD) analysis of dielectric flow behaviour and debris transport in micro-EDM milling, considering the effects of dielectric properties, inter-electrode gap (IEG) size (20–30 µm), and tool rotational speed (400–850 rpm). Four dielectric media, nitrogen gas, deionized water, HEDMA111 EDM oil, and sunflower seed oil, were investigated using a two-dimensional FEM-based model coupled with particle tracking simulations to evaluate debris mobility within the machining region. The results demonstrate that dielectric properties, particularly viscosity, strongly influence hydrodynamic behaviour and particle transport within the IEG. Under the adopted equal mass flow rate condition, nitrogen gas exhibited the highest flow velocities and the fastest debris evacuation due to the combined effects of its low viscosity and the resulting higher inlet velocity. Deionized water and HEDMA111 oil exhibit comparable intermediate behaviour, indicating that moderate viscosity variations within liquid dielectrics do not significantly alter the overall flow regime. In contrast, sunflower seed oil generates the most damped flow conditions, with reduced velocities and prolonged particle residence due to increased viscous resistance. Variations in IEG size produce only minor changes in evacuation efficiency compared with the dominant influence of dielectric properties, while tool rotational speed primarily affects velocity magnitude without altering qualitative transport behaviour. Full article

The increasing penetration of renewable energy sources introduces significant variability, low-inertia behaviour, and operational uncertainty into modern power systems, resulting in frequent frequency deviations and degraded dynamic stability. Conventional Load Frequency Control (LFC) approaches based on fixed-parameter PID controllers often exhibit limited disturbance rejection capability under nonlinear and stochastic operating conditions. This study proposes an enhanced LFC framework that integrates a PID controller optimised using the Flower Pollination Algorithm (FPA) with support from a Unified Power Flow Controller (UPFC) and a Redox Flow Battery (RFB) to improve frequency regulation, damping, and robustness in renewable-integrated low-inertia power systems. This study developed a MATLAB/Simulink single-area power system model comprising governor, turbine, and generator-load dynamics to evaluate controller performance under a 0.01 pu step disturbance, stochastic load variations, renewable energy fluctuations, and ±20% parameter uncertainty conditions. The FPA optimally tuned the PID controller gains using the Integral Time Absolute Error criterion to enhance transient response and disturbance rejection capability. Comparative analyses were conducted against conventional PID and fuzzy-based controllers using settling time, overshoot, RMS deviation, ITAE, and mean frequency deviation indices. Simulation results demonstrate that the proposed FPA–PID + UPFC framework significantly outperforms the conventional PID controller by achieving approximately 66.6% settling-time reduction, 72.1% RMS reduction, and 75.5% ITAE reduction. The proposed framework reduced settling time from 18.46 s to 6.16 s and substantially improved damping performance under stochastic disturbances. The coordinated integration of the UPFC and RFB further enhanced transient stability through dynamic power-flow regulation and rapid active-power compensation during disturbances. Sensitivity analysis under parameter uncertainty and stochastic operating conditions confirmed stable and reliable operation under stochastic disturbances and parameter uncertainty conditions. The proposed architecture, therefore, provides an effective, practically applicable solution for secondary frequency regulation in renewable-rich smart grids, low-inertia transmission systems, microgrids, and future distributed power networks. Full article

Background: Type II workplace violence by patients, relatives, or visitors is an occupational health and patient-safety concern in primary care. Cranston Ridge Medical Clinic (CRMC), a single urban family medicine and walk-in primary care clinic in Calgary, Alberta, plans to implement a universal, risk-informed workplace-safety bundle that is based on observable behaviour, situational risk, and documented safety concerns rather than demographic profiling. Methods: This article describes a single-site internal quality improvement and workplace-safety evaluation protocol. The comparison is CRMC usual practice during the pre-implementation baseline period; there is no concurrent external control group. The planned evaluation will use aggregate, de-identified operational data from a 12-month pre-implementation baseline, a four-week implementation period, and 12 months of post-implementation monitoring. All clinic staff will receive workplace-safety training as part of routine implementation. No staff, patients, or visitors will be recruited as research participants, and the evaluation will not use individual-level staff survey, interview, or focus-group data. Patient/visitor information will be used only as aggregate operational monitoring data when needed to assess safety, access, patient flow, and complaints. Intervention and analysis: The bundle includes worksite analysis, staff training, a brief arrival safety screen, a response algorithm, standardized reporting, monthly safety huddles, and post-incident support. The primary metric will be the Type II workplace-violence incident rate per 1000 clinic visits. Planned analyses include run charts, pre–post rate ratios, and Poisson or negative binomial segmented regression if monthly counts are sufficient. Implementation learning will be summarized from routine training records, safety-huddle summaries, post-incident debrief themes, and other aggregate de-identified operational indicators. Expected contribution: The protocol contributes a transparent, equity-sensitive, and operationally feasible model for balancing staff safety with patient access in primary care. Full article

Current evaluation of bypass graft performance relies predominantly on wall shear stress metrics, even though thrombosis and atherogenesis are fundamentally governed by particle transport and residence within disturbed flow regions. This disconnect limits the ability of conventional hemodynamic indicators to capture mechanisms directly linked to graft failure. In this study, we investigate how helical bypass geometry reorganises the flow and, consequently, modifies transport behaviour within the distal anastomosis by combining experimentally validated flow visualisation with computational fluid dynamics under pulsatile conditions. Particle transport was quantified using a controlled injection of 151 tracers, enabling direct assessment of retention and washout across the graft–anastomosis system. The straight configuration exhibited persistent recirculation structures that promoted localised particle retention and delayed clearance. In contrast, the helical geometry disrupted these structures, enhancing flow mixing and accelerating downstream transport. At late stages of the cardiac cycle, the helical configuration reduced residual particle retention by approximately 43% compared to the straight bypass. These findings demonstrate a transition from recirculation-driven retention to washout-dominated transport, providing a mechanistic basis for interpreting bypass performance beyond shear-based metrics. This transport-centred perspective provides a mechanistic link between flow organisation and particle residence, supporting the functional relevance of helical graft design while remaining distinct from direct modelling of biological thrombosis or atherogenesis. Full article

This study presents a combined experimental and numerical investigation of xanthan gum solutions at 100 and 300 ppm in turbulent smooth pipe flow under temperatures of 30–50 °C and Reynolds numbers of 8000–12,000. Water was used as the Newtonian reference fluid, while xanthan gum was modelled using temperature- and concentration-dependent shear-thinning properties. Experimental pressure-drop data were used to evaluate drag-reduction behaviour, whereas numerical simulations were employed to analyse the associated flow and heat-transfer responses. The results show that XG 100 ppm produced a relatively stable drag-reduction response of approximately 31–39%, while XG 300 ppm showed a wider and more condition-dependent range of about 25–45%. Water exhibited higher Nusselt numbers of approximately 68–106. In contrast, XG 100 ppm produced Nusselt numbers of approximately 45–69, while XG 300 ppm showed lower values of about 35–61. The corresponding heat-transfer reduction ranged from approximately 26–48% for XG 100 ppm and 23–46% for XG 300 ppm. These findings confirm a clear hydraulic–thermal trade-off, indicating that the xanthan gum concentration should be optimised according to both pressure-loss reduction and heat-transfer requirements. Full article

Introduction: Biological invasions are a major driver of biodiversity loss, particularly in freshwater ecosystems. The Iberian Peninsula, a hotspot of endemic diversity, is increasingly threatened by invasive predatory fish, which may exert higher predatory rates under warmer environmental conditions, disrupting/endangering native fish communities. One such species is the European catfish (Silurus glanis), a large and voracious apex predator. Despite growing research, most telemetry studies have focused on lentic systems, limiting our understanding of its behaviour in lotic environments. Moreover, high-resolution biologging approaches remain largely unexplored. Objective: This study aims to characterize the habitat use and activity patterns of European catfish in a non-native lotic section of the lower Tagus River, and to identify key environmental drivers shaping its predatory behaviour. Methodology: Adult individuals were tagged with radio telemetry transmitters equipped with temperature, pressure (depth), and 3D-accelerometer archival sensors. A preliminary controlled experiment established activity thresholds to classify behaviours. Ten adult fish were then actively tracked over one year, combining spatial data with high-resolution biologging. Habitat use and activity patterns were analyzed across seasonal and circadian scales. Generalized Additive Models (GAMs) were used to assess the effects of environmental variables on activity levels and depth use, while Hurdle models were applied to identify the environmental drivers influencing the occurrence and frequency of burst activity events (predatory behaviour proxies). Results: Fish displayed strong site fidelity, frequently using structured habitats near riverbanks. European catfish also showed clear seasonal and circadian patterns in habitat use and activity, occupying deeper habitats in winter and shallower areas in warmer seasons. Activity occurred year-round, increasing in spring and summer and peaking at dusk, being influenced by temperature, river flow, season, and time of day. Burst activity occurred more often in spring and at dusk. Conclusions: This study unveils insights on European catfish behaviour in invaded lotic systems, highlighting consistent patterns linked to environmental conditions. These findings can support more targeted and effective management strategies for controlling this invasive species. Full article

Background: Exercise plays a crucial role in the prevention and management of type 2 diabetes. During self-motion, optic flow provides visual information about heading direction and influences postural control. This study investigated postural responses and muscle activation in individuals with type 2 diabetes exposed to optic flow stimuli simulating self-motion, and examined whether these responses varied according to habitual physical activity over 12 months. Methods: Surface electromyographic (EMG) and stabilometric data were collected from 23 individuals during quiet standing under different visual motion conditions. Participants were classified as physically active or inactive based on standardized criteria. EMG activity was recorded bilaterally from the tibialis anterior and soleus muscles at baseline, 6, and 12 months. Center of pressure (COP) displacement was measured using two force platforms. Results: Stabilometric analysis revealed a significant effect of visual stimulus on COP displacement in both antero-posterior and medio-lateral directions, as well as on COP speed, indicating that optic flow modulates postural control. COP speed changes over time differed by sex, while medio-lateral sway showed time-dependent variations across sides and physical activity groups. EMG analysis showed a significant effect of visual stimulus on soleus activation, with no consistent effects for tibialis anterior. Conclusions: Optic flow significantly modulated postural control and lower-limb muscle activation in individuals with type 2 diabetes. Preliminary differences in response profiles associated with habitual physical activity level were observed, though these should be interpreted cautiously given the exploratory nature of the study. Larger, adequately powered studies are warranted to further investigate these associations. Full article

The transition to automated vehicles (AVs) introduces complex human factors and system-level challenges across Society of Automotive Engineers (SAE) Levels 0–5, with profound implications for the long-term viability of future transport infrastructure. Drawing on a synthesis of socio-technical, cognitive, and behavioural adaptation theories, this study develops an integrated framework to analyse the evolving relationships among driving automation, human behaviour, system risks, and urban sustainability. The findings demonstrate that human-factor risks are inherently nonlinear, meaning they do not decrease proportionally as technology advances; instead, risk profiles peak significantly at intermediate automation levels (SAE 2–3) due to supervisory fatigue and delayed takeovers, introducing severe traffic flow volatility and localised micro-congestion that directly compromise the environmental efficiency of sustainable transport systems. As these risks reconfigure into institutional and digital infrastructure dependencies at higher levels (SAE 4–5), the primary constraint shifts toward network readiness. Through an analysis of real-world AV deployment case studies and a structured narrative literature review, this paper identifies critical operational discontinuities and mixed-traffic complexities that threaten urban grid resilience. This study proposes a conceptual framework that translates these cross-level socio-technical insights into actionable deployment pathways, providing policymakers with adaptive governance models, transportation planners with mixed-traffic management strategies aimed at preserving network efficiency, infrastructure agencies with physical and digital readiness criteria for long-term asset sustainability, and AV developers with human–machine interface optimisation frameworks to secure human-centric safety within sustainable smart city networks. Full article

Meso-scale combustors experience major challenges associated with flame instability, excessive wall heat losses, and limited reactant residence time due to their high surface-to-volume ratios. This study numerically investigates the thermo-fluid behaviour of hydrogen-fuelled vortex flames in a frustum meso-scale combustor under stoichiometric conditions (φ = 1.0). Three outlet-diameter configurations of 6 mm, 8 mm, and 10 mm were analysed under stoichiometric hydrogen–air conditions at air mass flow rates of 40, 80, and 120 mg/s, corresponding to Reynolds numbers of approximately 624–1780, with Computational Fluid Dynamics (CFD) used to evaluate the influence of combustor geometry on thermal confinement, wall temperature distribution, and flame stabilisation characteristics. The numerical simulations were performed in ANSYS Fluent 14.0 using the RNG k–ε turbulence model coupled with the Eddy Dissipation combustion model. The results indicate that reducing outlet diameter significantly enhances thermal confinement and recirculation behaviour within the combustor core. The temperature contours showed a maximum flame temperature of approximately 2.23 × 10³ K, while the 6 mm outlet configuration produced a more compact and axially elongated high-temperature core compared with the 10 mm configuration. The 6 mm outlet enhanced thermal localisation by approximately 10.4% and increased residence time by 66.8% relative to the 10 mm outlet. The peak inner wall temperature ranged from approximately 752 K to 1085 K depending on outlet diameter and mass flow rate. The 6 mm outlet exhibited the highest average wall temperature of approximately 909 K, followed by the 8 mm outlet (879 K) and the 10 mm outlet (838 K). Compared with the 10 mm outlet, the 6 mm configuration increased the average wall temperature by approximately 8.5%, indicating improved thermal confinement and heat retention within the combustor. These results indicate that outlet diameter strongly influences the balance between thermal confinement, flame stabilisation, and flow resistance. Full article

The rapid growth in the electric vehicle sector has increased demand for advanced battery thermal management systems (BTMSs) with high heat-dissipation capacity and temperature uniformity. Immersion cooling using dielectric fluids has recently been recognized as a promising alternative technology to conventional indirect liquid cooling methods. This study investigates the thermal and hydrodynamic behaviour of a sixteen-lithium-ion cell battery (LIB) module immersed in low-viscosity dielectric fluids using three-dimensional computational fluid dynamics simulations. In this context, a total of twenty dielectric fluids are evaluated using the ANSYS Fluent solver, with particular emphasis on the effects of key thermophysical properties, including viscosity, density, specific heat capacity, and thermal conductivity. The simulation findings reveal that mineral oil and PAO4 yield the lowest maximum LIB cell temperatures, with a reduction of approximately 4 K compared to the least effective dielectric fluids, such as undecane and cumene. Moreover, in terms of temperature uniformity, mineral oil, Novec 7000, and PAO4 exhibit the most homogeneous temperature distributions among the twenty dielectric fluids. In addition, they show an improvement in the temperature uniformity index of approximately 32.4% compared with the least effective dielectric fluid, cumene. On the other hand, mineral oil and PAO4 generate significantly higher pressure drops because of their relatively high viscosities, which increases hydraulic resistance and pumping power requirements. These findings demonstrate that excellent thermal performance does not necessarily correspond to optimal overall thermo-hydraulic behaviour. Overall, the results confirm that immersion-BTMS performance is governed by a complex interaction between dielectric fluid thermophysical properties and flow behaviour, highlighting the importance of coupled thermo-hydraulic optimization in the selection of dielectric fluids for next-generation immersion-cooled battery systems. Full article

The increasing penetration of power electronic devices and distributed generation is significantly altering power quality conditions in low-voltage systems. While power quality assessment is commonly based on RMS currents, voltage quality indicators, and overall distortion metrics, these parameters may not fully reveal phase-selective harmonic behaviour in modern converter-dominated installations. This paper presents a measurement-based power quality assessment of a secondary school building equipped with a grid-connected photovoltaic (PV) system. A one-week monitoring campaign was conducted at the point of common coupling (PCC), capturing voltage, current, harmonic distortion, and power flow characteristics under real operating conditions. The results reveal pronounced phase-selective current harmonic distortion, with substantially elevated total harmonic distortion (THD_I) and total demand distortion (TDD) in one phase despite relatively balanced RMS current levels and acceptable voltage quality. The harmonic spectrum is dominated by low-order odd harmonics, whereas voltage distortion remains comparatively low and well balanced across phases. The study demonstrates that significant harmonic asymmetry may remain hidden in apparently balanced three-phase systems when assessment relies primarily on conventional RMS-based indicators. The findings highlight the importance of detailed current harmonic analysis and show that acceptable voltage quality does not necessarily imply acceptable current quality. The presented results provide measurement-based evidence of hidden harmonic asymmetry in modern low-voltage buildings and contribute to a better understanding of power quality challenges associated with nonlinear loads and distributed energy resources. Full article

Pipelines remain the primary mode of oil and gas transportation but are vulnerable to leaks that pose environmental and safety risks, particularly in two-phase flow systems. Conventional detection methods often struggle under transient multiphase conditions, while many data-driven studies rely on static evaluation metrics that do not reflect continuous monitoring requirements. This study develops a machine learning framework for leak detection using OLGA-simulated datasets from a previously published study, comprising approximately 180,000 labelled samples across nine leak scenarios and one no-leak case. Pressure, temperature, and mass-flow variables were enhanced through feature engineering to capture nonlinear leak behaviour. Random forest and extreme gradient boosting (XGBoost) classifiers were trained using an 80/20 stratified split with synthetic minority oversampling technique (SMOTE)-based balancing applied only to training data. XGBoost achieved 99.2% accuracy and reduced false positives by 53% relative to random forest while maintaining near-zero false negatives. A sliding-window suspicion framework extended static classification into time-dependent detection, producing delays of between 9.81 s and 82.04 s with zero false alarms in the no-leak scenario. Physical validation using pressure, flow, and fast Fourier transform (FFT) analysis confirmed that detections correspond to genuine hydraulic disturbances, demonstrating the reliability and physical credibility of the proposed framework. Full article

Cells operate as open thermodynamic systems where energy transformations and transport processes occur across membranes, exhibiting distinct thermo-electro-biochemical behaviours in healthy versus diseased states. Living organisms generate waste heat due to internal irreversibility, which dissipates into the environment and serves as an observable flow of information. By analysing this heat loss and its changes under external influences, new insights into cellular behaviour can be gained. This paper highlights recent advances in this thermodynamic approach, which frames living systems as black boxes, focusing on their input–output dynamics and introducing the emerging field of bioengineering thermodynamics. A key challenge in applying extremely low-frequency electromagnetic fields (ELF-EMF) to proliferative disorders has been the empirical selection of effective field parameters. To address this, we employed a bio-thermodynamic engineering model to calculate the ELF frequency that maximizes mean entropy changes based on cellular biophysical parameters. This entropy change corresponds to a metabolic shift that reduces cell proliferation. Experimental validation was performed on six human cancer cell lines, where proliferation rates served as indicators confirming the model’s predictions. For the first time, this approach enabled the calculation and experimental validation of ELF frequencies selectively effective on different cell types, demonstrating a promising method for targeted therapeutic applications. Full article