Search Results (2,549)

Desulfurization ash (DA) is a kind of industrial solid waste generated during flue gas desulfurization. To overcome the limited utilization of reactive calcium-bearing constituents and the insufficient mineralogical stability of DA, this study proposes a thermal CO₂ modification approach based on the synergistic coupling of oxidation and carbonation, and systematically investigates the associated evolution of mineral phases and microstructural features. The effects of reaction temperature, CO₂ flow rate, and reaction time are evaluated using TG-DSC, XRD, FT-IR, SEM-EDS, particle size analysis, and carbon-sulfur analysis to elucidate the reaction behavior of DA under a CO₂ atmosphere. The results demonstrate that reaction temperature is the dominant factor governing the modification process. During heating, CaSO₃ is preferentially oxidized to CaSO₄ under the CO₂ atmosphere, thereby stabilizing the sulfur-bearing components. Subsequently, Ca(OH)₂ undergoes carbonation to form CaCO₃, simultaneously contributing to CO₂ sequestration. Under the optimized conditions of 450 °C, a CO₂ flow rate of 120 mL/min, and a reaction time of 60 min, the resulting CaCO₃ exhibits a pronounced needle-like CaCO₃ morphology, while the CO₂ uptake reaches a maximum of 16.71%. These findings clarify the coupled oxidation–carbonation mechanism and mineral transformation behavior of DA during thermal CO₂ modification, providing a theoretical basis and technical reference for the low-carbon utilization of industrial solid wastes. Full article

This study presents a sensor-fused field investigation and simulation-based analysis of four horizontal and vertical traffic-calming devices—two raised speed tables, a speed hump, and a raised crosswalk—installed along a 5250-ft two-lane residential collector in Nashville, TN, USA. A dual-sensor architecture combining a Miovision Scout video-based vehicle counter and WAAS/EGNOS-augmented GPS probe-vehicle logging (5 m 3-D RMS horizontal accuracy, 1 Hz sampling) was used to reconstruct 30 quality-controlled free-flow vehicle trajectories and 12-h per-lane volume counts. A spatial kinematic transform (a = v·dv/dx) was applied to extract device-specific approach-deceleration and post-device recovery-acceleration rates, and a three-parameter log-logistic cumulative-distribution function was fitted to the field-observed desired-speed percentiles (root-mean-square error below 0.043 for both speed-table devices). The camera- and GPS-derived observations were used to calibrate and statistically validate a PTV VISSIM microsimulation replica of the corridor, achieving a mean-speed calibration error of 0.71% or better at every device, a GEH statistic below 1.5 at all four analysis turning movements, and independent travel-time validation errors of 5.7–12.1%, within the accepted 15% threshold. The validated model was then used to reconstruct device- and spacing-specific May–Keller macroscopic speed–density–flow relationships, calibrated against simulated capacities of 650–775 vehicles per hour per lane at 350-, 700-, and 1050-ft device spacing. Results show capacity reductions of 20–33% relative to free-flow conditions and yield kinematically derived maximum recommended spacings of 265–630 ft to maintain crossing speeds at or below 15 mph, depending on device geometry. The findings demonstrate a reproducible, low-cost sensor-fusion workflow for quantifying the safety–capacity trade-off of traffic-calming corridors and for informing the design of sensor-in-the-loop adaptive-calming infrastructure. Full article

Thermal transpiration enables a Knudsen pump to transport gas without moving components. An axial-integration formulation based on pre-computed transport coefficients from the linearized Shakhov kinetic model is applied to a single-stage unit comprising a circular microchannel and a circular macrochannel in series, with opposite wall-temperature gradients. The pressure-generation and gas-transport capabilities are characterized by the maximum pressure difference or thermomolecular pressure difference (TPD), the maximum mass flow rate, the equivalent TPD, the equivalent flow resistance, and the complete mass-flow-rate–pressure-difference characteristics. The principal quantitative calculations cover temperature differences ranging from 10 to 50 K, while the 75 and 100 K cases are retained only to assess the persistence of the calculated trends. The formulation reproduces benchmark experimental TPD data with a maximum absolute relative deviation of 12.5% and a mean absolute relative deviation of 6.7%, and shows excellent agreement with numerical data from the literature, with deviation below 1%. A decomposition of the microchannel and macrochannel contributions shows that a macrochannel contributing little to the total equivalent flow resistance may nevertheless produce appreciable reverse thermal transpiration. At the baseline condition of the study and for an inlet pressure $P_i=10 \mathrm{kPa}$, the macrochannel contributes only 0.37% of the total equivalent flow resistance but cancels 15.2% of the microchannel equivalent TPD. Over $P_i=1\text{–}50 \mathrm{kPa}$, the temperature-difference sensitivity of the TPD ranges from 0.93 to 1.05, whereas the microchannel-radius sensitivity varies from −0.41 to −1.62. For the maximum mass flow rate, the microchannel-radius sensitivity ranges from 2.06 to 2.56 and the microchannel-length sensitivity remains close to −1, while the macrochannel-length effect is negligible. Increasing the macrochannel radius improves both limiting outputs, i.e., TPD and maximum mass flow rate, but with progressively diminishing benefits from further enlargement of the macrochannel. These results provide a quantitative basis for preliminary dimension selection while explicitly identifying the limitations associated with linearization, finite channel length, fully developed flow, and neglected interface losses. Full article

Culvert construction at stream crossing sites can lead to zones of high-velocity water flow which can disrupt the dispersal and connectivity of species of greatest conservation need (SGCN) in Texas. To help inform effective culvert design, the swimming performance of the following seven fish species has been measured, the first three of which are SGCN themselves, and the last four serve as hosts for glochidia of SGCN mussels (mussel genera indicated in parentheses): Colorado Roundnose Minnow, Texas Shiner, Headwater Catfish, Largemouth Bass (host for Lampsilis spp.), Green Sunfish (host for Lampsilis spp.), Channel Catfish (host for Cyclonaias spp.) and Blacktail Shiner (host for Fusconaia spp.). The primary objective was to measure the critical swimming speeds (U_crit) under a range of relevant temperatures (15, 22.5, and 30 °C) to be used in site-specific calculations of culvert water velocities (Vf). A secondary objective was to collect additional physiological endpoints of relevance to overall swimming performance, including maximum burst swimming speed (U_max), metabolic rate measurements (i.e., standard (SMR), maximum (MMR) and aerobic scope (AS)) and calculations of cost of transport (COT) and optimal swimming speed (U_opt). As expected, U_crit tended to increase with increasing temperature for several species with metabolic rate measurements following congruent trends, whereas U_max exhibited thermal independence for all species. Full article

The results of a numerical modeling of the laminar water flow and mixed conductive–convective heat transfer in highly elongated heatsink with continuous rectangular microchannels, and a width-to-length ratio of 625 (i.e., 0.2 mm to 125 mm), are presented, along with two methods of fluid entry (along and perpendicular to the base of the heatsink) for a wide range of surface heat flux density q from 30 to 2000 kW/m² and water volume flow rate from 10 to 50 L/h (${Re}_D=26-128$). It has been demonstrated that: (1) The elongated microchannel maintains its effectiveness in heat removal by water, even under conditions of high q-value; however, in the terminal sections the temperature can approach the maximum permissible operating level for high-loaded silicon electronic components (~95–100 °C). (2) For microchannel heatsinks, the direction of the incoming flow is not of significant influence, since the microchannel structure, even with a height of 2.5 mm, exhibits substantial diffusivity and the flow in the inlet area rapidly turns along the heat distribution base; this flow further possesses the same characteristics as in the case of the input flow parallel to the axis of the microchannels. The developed model allows for the optimization of geometric, kinematic and thermal parameters of highly efficient microchannel devices, depending on the expected operating conditions. Full article

Background/Objectives: Benign prostatic hyperplasia (BPH) with lower urinary tract symptoms (LUTS) affects up to 60% of men by age 90. With Singapore’s aging population, minimally invasive surgical therapies (MIST) have emerged as effective alternatives for patients unsuitable for traditional surgery. We sought to evaluate real-world outcomes of MIST procedures: Water Vapor Thermal Therapy (WVTT) and Prostatic Urethral Lift (PUL) in treating BPH-related LUTS. Methods: This is a retrospective analysis of 62 MIST patients treated at a tertiary hospital in Singapore between August 2021 and February 2025, with a minimum of three-month follow-up. Primary outcomes included improvements in maximum urinary flow rate (Qmax), International Prostate Symptom Score (IPSS), and Quality of Life (QoL) scores. Secondary outcomes included complications, re-treatment rates, and healthcare utilization metrics. Results: Thirty-six patients underwent WVTT, and 26 underwent PUL. Median age was 67 years, with a mean prostate volume of 61 cm³. At three months, both procedures showed improvements: Qmax increased by 4.28 mL/s (WVTT, p < 0.001) and 3.46 mL/s (PUL, p = 0.06); IPSS decreased by 12.8 (WVTT, p < 0.001) and 12.5 (PUL, p < 0.001); QoL scores improved by 2.53 (WVTT, p < 0.001) and 3.31 (PUL, p < 0.001). The complication rate was 32.3%, with complications being predominantly Clavien–Dindo grades 1–2. Day surgery was achieved in 83.9% of cases, with only 4.8% requiring readmission within 30 days. At three months, 98.4% were catheter-free, and excluding prior catheter-dependent patients, 82.4% were medication-free. At a median follow-up of 5.9 months, the re-treatment rate was 3.2%. Conclusions: MIST procedures are safe and effective for BPH-LUTS, showing comparable outcomes between WVTT and PUL while optimizing healthcare resource utilization. Full article

Non-uniform discharge temperature during sinter cooling is a practical issue in ironmaking, as local overheating may increase the thermal load on downstream conveying equipment. To mitigate insufficient cooling in the upper sinter bed under the conventional bottom-blowing mode, this study developed a three-dimensional transient CFD model for an industrial continuous annular cooler and optimized the air-supply strategy in Zones IV and V. Under the conventional condition, ambient air is supplied independently to Zones IV and V from the bottom wind boxes. In the novel air-supply strategy, while keeping the total fresh cooling-air flow rate in the final cooling region unchanged, ambient air is introduced from the upper side of Zone V and discharged from its bottom; the outlet gas from Zone V is then supplied to the bottom of Zone IV, forming a serial air-supply path. The results show that the novel arrangement improves the spatial matching between the cooling gas and the sinter bed during final cooling and suppresses the local high-temperature region near the discharge end. The maximum discharge temperature decreases from 459 K to 410 K, below the process limit of 423 K, while the average discharge temperature decreases from 377 K to 364 K. Based on the enthalpy-flow difference calculation, the predicted recoverable waste heat also increases under the novel condition. These findings suggest that redesigning the gas-flow route in the final cooling region can effectively enhance the uniformity of the discharge temperature in industrial annular coolers. Full article

Unmanned aerial vehicles (UAVs) used in low-altitude mobility and electric aviation are increasingly required to carry higher payloads, operate for longer durations and maintain reliable performance under constrained installation conditions. In compact power cabins, batteries, controllers, power distribution units and auxiliary actuators are densely arranged, making cabin thermal management a critical design issue. In this study, a full-scale conjugate flow and heat transfer model is developed for the power cabin of a UAV and validated against thermal management experiments. The validated model is then used to examine how a conventional rectangular ram-air inlet and a proposed stepped ram-air inlet affect air capture, internal flow organization and temperature distribution. The inlet area of the rectangular configuration is first varied to establish a baseline, after which the transition arc ratio, spacing ratio and area ratio of the stepped inlet are parametrically investigated. The results show that increasing the rectangular inlet area from 0.002 to 0.008 m² increases the total captured mass flow rate from 0.258 to 1.084 kg/s, whereas the cabin average temperature decreases by 0.34 °C. By contrast, the cabin maximum temperature decreases nonlinearly, with a 27.2% reduction when the area increases from 0.004 to 0.006 m². These results indicate that air capture and the cabin average temperature alone are insufficient to evaluate cooling effectiveness in a compact multi-source cabin. For the stepped inlet, the transition arc ratio controls the turning of the incoming flow, the spacing ratio governs shielding and backflow between adjacent inlet sections, and the area ratio redistributes the dominant inlet sections. The best-performing stepped-inlet configuration among the tested cases increases the captured mass flow rate by 32.8% compared with the rectangular baseline under the same opening constraint and improves the utilization of cooling air around high heat load components. This study demonstrates that ram-air inlet design for UAV power cabins should be treated as a coupled problem of the mass flow capture, internal flow path and component-level thermal response. Full article

Recent efforts to address flooding have explored incorporating flow-reduction capabilities into existing infrastructure. Roadside ditches have historically been viewed as an underutilized component of flood reduction, and a two-stage design has been proposed that modifies a conventional trapezoidal ditch by incorporating bench insets along the main channel. While it is expected that this second stage becomes inundated during storm events, resulting in flow attenuation, the exact impacts of this design are unknown. This study quantified the impact of the two-stage design by modeling a roadside ditch corridor in eastern Iowa. An existing single-stage ditch was converted to a two-stage design, and a HEC-RAS model was constructed to investigate the ditch’s impacts for four design storms (1-year, 2-year, 5-year, and 10-year). In the modeled results, peak flow rates were reduced by 22%, 21%, 7.5%, and 4.3%, respectively, while water volume reductions were near 6%. Maximum velocities throughout the ditch corridor also decreased, with reductions spanning 32% (1-year)–45% (10-year). These results indicate that increased travel times and infiltration associated with the two-stage design provide hydrologic and hydraulic benefits by lessening flood and erosion risk. While further study is needed to verify this behavior through monitoring and modeling at other locations, our findings suggest that two-stage ditches can be a useful best management practice for the transportation community. Full article

Rainfall–runoff modeling is a key challenge in hydrological research. Despite the extensive application of long short-term memory (LSTM) networks in rainfall–runoff modeling, our understanding of the influence of different hyperparameter configurations on various hydrograph components, as well as the linkages between hydrological concepts and LSTM architectures, remains elusive. Here, we integrated Multi-Objective Particle Swarm Optimization (MOPSO) with LSTM hyperparameter optimization by targeting the root mean square error of the overall hydrograph (RMSE_all), high-flow (RMSE_high) and low-flow (RMSE_low) dynamics, and water volume deviation (Dv). The MOPSO-LSTM framework was applied to the upstream catchments of the Miyun Reservoir in Beijing, China. At a lead time of 1d, the optimal solution achieved an NSE of 0.920 in the Chaohe River Basin, with a minimum RMSE_all of 0.848 m³/s, RMSE_high of 2.081 m³/s, RMSE_low of 0.382 m³/s, and Dv of 0.002%. However, as the lead time increased to 3 and 7 days, the maximum NSE declined to 0.747 and 0.560, respectively, with process-related metrics deteriorating more substantially than water balance-related metrics. The Baihe River Basin performed better, with maximum NSE and KGE values of 0.949 and 0.970 at a lead time of 1d. Clear trade-offs among different evaluation objectives were further identified, particularly the competitive relationship between RMSE_high and RMSE_low, as well as the coupling between RMSE_low and Dv. SHAP (Shapley additive explanation) and partial dependence plots (PDPs) were used to quantify and interpret the effects of hyperparameters on model performance, and the results showed that learning rate, number of units, and lookback window served as the most influential hyperparameters. Moreover, optimization preferences resulted in distinct hyperparameter configurations, where Dv-oriented solutions favored smaller learning rates, longer lookback windows, and larger batch sizes than RMSE-oriented solutions. Compared with the Chaohe River Basin, the larger Baihe River Basin favored LSTM configurations with longer lookback windows, more hidden units, higher learning rates, and lower dropout rates, which was associated with the hydrological memory of the catchment. Overall, this study provides a novel multi-objective LSTM optimization framework, improving the understanding of LSTM hyperparameters and offering practical guidance for hydrological prediction and water resource management. Full article

Engaging adolescents in regular physical activity remains a major public health challenge; consequently, increasing attention is being directed toward technologies that make exercise more attractive, task-oriented, and engaging. Active video games and non-immersive virtual reality systems are particularly promising because they combine physical exertion with feedback, gamification, and movement-based interaction. This study examined whether a biathlon exergame performed on an unstable ICAROS Cloud platform using the ICAROS App can elicit favorable physiological and psychological responses in adolescents, and whether these responses depend on body position. Eighty secondary school students, including 41 girls and 39 boys, completed two 10 min Biathlon trials: one in a standing position and one in a quadruped kneeling position, with the trial order counterbalanced. The percentages of maximum heart rate (%HR_max), perceived exertion, enjoyment of physical activity, and flow state were assessed. The standing condition elicited higher exercise intensity than quadrupled kneeling (71.42 ± 9.61 vs. 62.09 ± 9.04%HR_max; p < 0.001), and was also associated with higher perceived exertion, enjoyment, and flow. Similar response patterns were observed in girls and boys. These findings highlight the potential of unstable-platform exergaming as a practical and engaging approach to technology-supported physical activity promotion in developmental ages. Full article

With continuously growing heat loads of microelectronic and aerospace equipment, spray cooling stands out as an effective high-heat-flux thermal management technology. Though room-temperature spray cooling has been extensively explored, liquid nitrogen spray cooling, a competitive cryogenic cooling approach, still lacks clear parametric laws and heat transfer limits due to harsh and unstable low-temperature test conditions. In this paper, experiments are carried out on a semi-closed liquid nitrogen spray cooling test rig to investigate how spray flow rate, chamber pressure and spray height affect the critical heat flux (CHF) and cooling efficiency of heated surfaces. Experimental results reveal that the maximum CHF reaches 284 W·cm⁻². Increasing flow rate raises the heat transfer limit but cuts cooling efficiency, while both CHF and efficiency are barely sensitive to chamber pressure. The spray height enabling full wall coverage is optimal, delivering a peak cooling efficiency of 32.9%. The simulation explains the relationship between liquid film evolution and CHF/cooling efficiency. Simulations demonstrate that liquid film thickness rises first and then decreases moderately with growing spray height, inconsistent with the conventional view that thinner films yield superior heat transfer. The findings provide useful guidance for the design and optimization of cryogenic spray cooling systems. Full article

Background/Objectives: To evaluate the surgical and functional outcomes of robot-assisted simple prostatectomy (RASP) for men with bothersome lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH), aiding informed clinical decision-making. Methods: We conducted a prospective study of 69 patients undergoing RASP for BPH-related LUTS or acute urinary retention (AUR). Three high-volume robotic urologists from a single center, utilising a modified Millins technique, performed the RASP procedures. Pre-operative data included demographics (age, prostate-specific antigen (PSA), prostate volume), LUTS measures (International Prostate Symptom Score (IPSS), quality-of-life (QOL), flow rates, pad use), and intraoperative parameters (operative time, blood loss, histology, hospital stay). Postoperative outcomes were collected at 6–8 weeks and included symptom scores, flow rates, pad use, and patient satisfaction. Data were analysed using descriptive statistics and multivariate linear logistic regression; significance was set at 95% confidence. Results: Median patient age was 74 years (interquartile range (IQR) 72–77) with a median prostate volume of 143 cc (IQR 123–195) and preoperative IPSS of 19 (IQR 15.0–23.0). Median console time was 60 min (IQR 50.0–65.0), estimated blood loss was 350.0 mL (IQR 200–500), and specimen weight was 105.5 g (IQR 67.25–132.5). Median hospital stay was 1.0 day; all patients passed their trial of void (TOV) postoperatively, with an IPSS improvement of 78.9% (12 points), QOL improvement of 75% (3 points), maximum flow rate (Qmax) increase of 16.3 mL/s and an overall patient satisfaction of 10 out of 10 (extremely satisfied), independent of specimen size, operative duration, or pad usage. Conclusions: RASP appears to be a safe and effective surgical option for men with high-volume BPH and bothersome LUTS, offering substantial symptom improvement and excellent patient satisfaction. Its advantages may extend to patients with very large prostates or concurrent bladder pathology. However, findings are limited by our modest sample size and short follow-up. Larger prospective and comparative trials are warranted to better define the role of RASP in the treatment algorithm for BPH. Full article

Landslide-induced waves are primarily controlled by granular dynamics during landslide–water impact. While particle size, velocity, and volume are recognized influences, the role of internal grain arrangement and segregation remains less clear. This study employs a coupled CFD-DEM model to investigate how vertical permutation of three fixed grain fractions and layered configurations affect surge generation and propagation. Simulations using three particle sizes (1, 3, and 5 mm) in six initial arrangements reveal that fine particles dominate leading wave formation through efficient momentum transfer, yielding an overall wave height growth of 5.22% and a maximum local growth rate of 2.42%. Grain size segregation governs deposit morphology, with larger particles migrating preferentially along the flow direction. Increasing still-water depth systematically shifts surge characteristics from strongly nonlinear, high-amplitude shallow-water waves to more linear, longer-wavelength, smaller-amplitude deep-water features. Energy dissipation, which is linked to reduced equivalent water depth, decreases wave celerity with propagation distance. The model reproduces granular collapse experiments with a relative error below 5%, confirming that granular segregation critically controls surge dynamics and providing a refined framework for simulating natural landslide-generated waves. Full article

This study specifically investigates the operating range of a normal Francis turbine through the production of experimental data and characteristic performance curves under both constant and variable rotational speed operating conditions. For the constant speed condition, a specific speed of 204.6 was found for turbine maximum efficiency attained with a guide vane aperture at 60%. The variable speed tests were conducted by keeping the specific speed around 204.6 with the guide vane aperture fixed at 60%. These tests have successfully produced results of turbine maximum efficiency very close to the maximum efficiency for the constant speed condition. The most important contribution of this paper is to report an increase in the operational range of the hydraulic turbine with variable speed operation, particularly when working at a lower flow rate and water head. The results obtained have demonstrated incomplete dynamic similarity between homologous Francis turbines. In other words, the concept of identical hydraulic turbines working with variable speed and producing the same maximum efficiency has been verified. The work also demonstrates an approach to the operation of hydroelectric generating units, aiming at improved compatibility between water availability and the electrical energy supplied to consumers. Full article