Experimental study on heat release characteristics and performance parameters of two-phase rotating detonation combustor under different equivalence ratios and outlet area ratios

Computed tomography can assess aortic valve stenosis by planimetry, enhances the continuity equation, reveals an anatomical ratio that mimics the dimensionless velocity index and demonstrates limitations in the use of calcification in stenosis severity assessment.

The tokamak is a toroidal device that utilizes magnetic confinement to achieve controlled nuclear fusion. One of the major technical challenges hindering the development of this technology lies in effectively dissipating the generated heat. In this study, the inner blanket structure of a tokamak is selected as the research object, and a multi–physics numerical model coupling magnetic field, temperature field, and flow field is established. The effects of background magnetic field strength, blanket channel width, and inlet velocity of the liquid metal coolant on the thermal–flow characteristics of the blanket were systematically investigated. The results indicate that compared with the L-shaped channel, the U-shaped channel reduces flow resistance in the turning region by 6%, exhibits a more uniform temperature distribution, and decreases the outlet–inlet temperature difference by 4%, thereby significantly enhancing the heat transfer efficiency. An increase in background magnetic field strength suppresses coolant flow but has only a limited impact on the temperature field. When the background magnetic field reaches a certain strength, the magnetic field has a certain hindering effect on the flow of the working fluid. Increasing the thickness of the blankets appropriately can alleviate the hindering effect of the magnetic field on the flow and improve the velocity distribution in the outlet area.

As a core component of gas turbines, the aerodynamic performance of the exhaust diffuser directly impacts turbine efficiency. Connected to the last-stage outlet, it guides the airflow while facilitating kinetic energy recovery. However, its structural volume not only increases the overall dimensions of the gas turbine but also restricts equipment compactness and layout flexibility. To address this, the numerical simulation method (based on the shear stress transfer model) is used to design the key geometric parameters of a gas turbine exhaust diffuser, including the inclination angle of the support plate, the shape of the tail cone and the expansion angle of the outer cone. The results show that the designed swept-back strut significantly improves the flow in the annular diffuser channel and affects the back pressure of the upstream turbine. By designing the tail cone shape and its length, the position of the maximum diffuser section of the diffuser can be changed, and the aerodynamic performance of the diffuser can be improved. The change in the flare angle of the outer cone does not affect the position of the maximum diffuser section, but with the increase of the angle, the aerodynamic performance of the diffuser decreases. In this studied, the maximum static pressure recovery coefficient per unit area of the diffuser is increased by 31.03%, the total pressure loss coefficient is reduced by 34.09%, while the length of the diffuser can be shortened by 30.34%, and the outlet area can be reduced by 20.27%.

Spatiotemporal patterns of nitrous oxide emissions in the Guitang River: Interplay of wastewater discharge and ecological restoration.

ABSTRACT Rapid urbanization has reduced traditional features in Acehnese vernacular houses, while the demand for energy-efficient and environmentally friendly housing continues to grow. This study examines the sustainability of passive ventilation strategies in Rumoh Aceh and their potential application to the facade design of modern house in the Hadrah Housing complex, Banda Aceh, Indonesia. Temperature, humidity, and wind speed were measured over three consecutive sunny days from 11.00 to 14.00 WIB in the dining room. Results showed indoor temperatures of 31.2°C − 31.6°C and humidity levels of 67% − 72%, both exceeding SNI thermal comfort limits. CFD simulations revealed that the existing outlet – inlet ratio of 1:1.5 failed to generate effective airflow due to poorly designed openings and shared walls. While orientation is fixed, applying Rumoh Aceh strategies, such as balanced or larger outlet areas, open plans, vertical ventilation through stack effects, porous facades, clerestory windows, shading vegetation, and openings aligned with local wind direction can enhance airflow and reduce heat buildup. Using a Value Engineering (VE) approach, the study proposes adaptive, cost-effective solutions that integrate vernacular principles with modern design. These findings underscore integrating Rumoh Aceh passive ventilation strategies into modern facade design to enhance thermal comfort and climate responsiveness.

During the three-roll planetary rolling process, the cooling efficiency of conventional nozzle structures is insufficient, which can easily lead to copper adhesion on the roll surface, product quality degradation, and shortened roll lifespan, thereby limiting both the quality of copper tubes and overall production efficiency. To enhance the performance of the cooling system, this study proposes a novel elliptical nozzle structure and develops a multiphysics coupled model to reveal the effects of nozzle inclination angle and gas–liquid pressure ratio on cooling behavior. An independently constructed experimental platform was used to measure jet flow patterns and the surface temperature of alloy steel plates under various parameter conditions, thereby validating the accuracy and reliability of the numerical model. The results indicate that, under the same effective outlet area, the elliptical nozzle significantly increases jet exit velocity and overall cooling efficiency. To address the issues of high computational cost and low efficiency during optimization using finite element simulations, a high-accuracy surrogate model based on a Random Forest (RF) algorithm was introduced, and the geometric parameters of the nozzle were globally optimized using a Particle Swarm Optimization (PSO) algorithm. Ultimately, the combined RF-PSO strategy improved the average heat transfer coefficient by 55.57%, markedly enhancing the roll cooling performance and providing a solid theoretical basis and methodological reference for high-performance cooling system design and precision copper tube manufacturing.

Abstract This paper explores the mechanism by which the aspect ratio of a rectangular outlet affects the lift performance of an airfoil by optimizing the shape of the ducted fan outlet. Under the conditions of fixed outlet area, duct position, and flap deflection angle, changing the circular outlet to a rectangular one can form a thinner and more diffuse jet, significantly expanding the coverage of the high-speed airflow on the upper surface of the wing. The results show that compared with the circular outlet, the rectangular outlet can produce a higher lift coefficient, and as the aspect ratio increases, the lift and drag coefficients increase simultaneously. The circular outlet has a prominent lift-enhancing effect at the leading edge of the flap, but it is difficult to maintain, while the rectangular outlet forms a more uniform static pressure distribution in the flap area, achieving a sustained and stable lift-enhancing effect. The thin jet adheres closely to the airfoil by enhancing the Coanda effect, effectively alleviating the adverse pressure gradient and suppressing flow separation.

Labile heavy metals in sediments controlled by terrestrial organic matter based on isotopic and molecular signatures in an anthropogenic estuary.

Abstract The full load vortex in a hydraulic turbine can self-excite, leading to large synchronous pressure fluctuations that are transmitted to the entire hydraulic circuit resulting in potentially large power oscillations. Its root cause stems from the runner outlet area and the draft tube. Unsteady computational fluid dynamics (CFD) has proven successful at predicting many dynamic phenomena in hydraulic turbines. Our analyses show that this is also the case for the full load self-excitation of a medium to low head Francis model scale turbine. Our results indicate that blade outlet cavitation is present, when the cavitating full load vortex self-excites. Theoretical considerations show that for at least one type of self-excitation, a second elasticity, i.e. a second volume of cavitation, is a necessary condition, while an appropriate phase shift between the oscillations of the two elasticities will finally result in self-excitation.

Ensuring a smooth rate of efflux of particles from an outlet without unpredictable clogging events is crucial in processing powders and grains. We show by experiments and simulations that an obstacle placed near the outlet can greatly suppress clog formation in a 3-dimensional granular flow; this counterintuitive phenomenon had previously been demonstrated in 2-dimensional systems. Remarkably, clog suppression is very effective even when the obstacle cross section is comparable to that of a single grain and is only a small fraction of the outlet area. Data from two dissimilar obstacle shapes indicate that the underlying mechanism for clog suppression is geometric: while the magnitude of the effect can be affected by dynamical factors, the optimal location of the obstacle is not and follows a simple geometric rule. An optimally placed obstacle arranges for the most probable clogging arch to be at a perilous and unstable spot, where the flow geometry is at a point of local expansion and a slight perturbation leaves the arch without downstream support. This geometric principle does not rely on previously conjectured dynamical mechanisms and admits generalization to other agent-based and particulate systems.

The harsh environment and lightweight structure of the scramjet engine make the fluid–thermal–structure interaction (FTSI) effects significant. This paper conducts coupled analysis of a scramjet for 20 s, investigating the interaction between the thin-walled structure and supersonic combustion (result at 0 s as the benchmark without considering the FTSI effect). During the operation, the flame on the upper wall changes from the cavity-assisted jet wake-stabilized combustion into the cavity shear layer-stabilized combustion. While the lower flame gradually moves forward to the jet, the moving distance decreases with the inflow from Ma2.5 to Ma3.5. These variations induce the structural deformation mode from downward depression of the lower wall to upward bugling of the upper wall. Since the FTSI effects are evident for Ma3.0 inflow, an in-depth investigation of this condition is studied. For Ma3.0 inflow, a separation zone progressively emerges on the lower wall and it promotes the flame toward the jet, with the combustion changing into jet wake-stabilized mode. On the contrary, the backward moving flame on the upper wall delays the corner flow separation point toward the cavity. The performance parameters are also influenced by the FTSI effect. Inlet and outlet areas of the combustion chamber increase by 12% and 11%, respectively. The thrust undergoes the process of decreasing and then increasing.

Experimental Investigation of Ramjet Rotating Detonation Fueled by Kerosene under Different Outlet Area Ratios with S-Shaped Isolator

Heavy metal contamination in groundwater has emerged as a significant environmental issue, driven by rapid industrialization and intensified human activities, particularly in southern China. Heavy metal pollution in groundwater often presents complex spatial patterns and multiple sources; understanding the spatial heterogeneity and controlling factors of heavy metals is crucial for pollution prevention and water resource management in industrial regions. This study applied spatial autocorrelation analysis and self-organizing maps (SOM) coupled with K-means clustering to investigate the spatial distribution and key influencing factors of nine heavy metals (Cr, Fe, Mn, Ni, Cu, Zn, As, Ba, and Pb) in a typical industrial area in southern China. Heavy metals show significant spatial heterogeneity in concentrations. Cr, Mn, Fe, and Cu form local hotspots near urban and peripheral zones; Ni and As present downstream enrichment along the river pathway with longitudinal increase trends; Zn, Ba, and Pb exhibit a fluctuating pattern from west to east in the piedmont region. Local Moran’s I analysis further revealed spatial clustering in the northwest, riverine zones, and coastal outlet areas, providing insight into potential source regions. SOM clustering identified three types of groundwater: Cluster 1 (characterized by Cr, Mn, Fe, and Ni) is primarily influenced by industrial pollution and present spatially scattered distribution; Cluster 2 (dominated by As, NO3−, Ca2+, and K+) is associated with domestic sewage and distributes following river flow; Cluster 3 (enriched in Zn, Ba, Pb, and NO3−) is shaped by agricultural activities and natural mineral dissolution, with a lateral distribution along the piedmont zone. The findings of this study provide a scientific foundation for groundwater pollution prevention and environmental management in industrialized areas.

Effect of dry / wet steam outlet area ratio on the performance of supersonic separator

Flood disturbances have an impact on the economy and society. Previous research has focused on the causes of floods resulting in urbanization, poor drainage networks, maintenance, and climate change. This study aims to develop an integrated stormwater management solution in the Kota Samarahan district's floodplain area in Sarawak, Malaysia. This paper aims to evaluate the causes of the flood and the potential of detention storage, namely StormPav as a sub-surface detention pond storage permeable parking lot to mitigate flood in the study area. The study area has experienced floods almost every year since 2015, during the Northeast Monsoon season in the middle of December and early January. The main outlet received about 2286 m3 of overflow water when projected with 10 Average Recurrence Interval (ARI) rainfall, causing a flash flood to the commercial building next to the main outlet area. The field study is conducted to evaluate the existing hydraulic drainage network. The existing drainage network of the catchment area is modelled in Stormwater Management Model (SWMM) version 5.1. Next, the scenario with a flood is simulated in SWMM. Finally, flood mitigation using StormPav is assessed using Low Impact Development (LID) control in SWMM. The results show that StormPav reduced peak flow runoff by about 32.55% and 31.15% for 10 ARI and 100 ARI, respectively, with subsurface detention storage.

ObjectiveTo explore the value of non-enhanced magnetic resonance thoracic ductography (NMRTD) combined with MR abdominopelvic scanning in the diagnosis of chylous leakage of the female reproductive system.MethodsA retrospective analysis was conducted on the multimodal imaging data from non-enhanced magnetic resonance thoracic ductography (NMRTD), direct lymphangiography (DLG), and abdominopelvic magnetic resonance imaging (MRI) for 18 female patients with reproductive system chylous leakage. Among these patients, 7 had vaginal chylous leakage, 10 had vulvar cutaneous chylous leakage, and 1 had both conditions.The rate of successful visualization of the thoracic duct, the consistency of the drainage directions of the outlet of the thoracic duct, and the degree of visualization of each segment of the thoracic duct by NMRTD and DLG were analyzed. A retrospective analysis was performed on the abnormal manifestations of abdominopelvic MR.ResultsNMRTD had a significant advantage over DLG in terms of successful visualization of the thoracic duct (94.4% vs. 66.7%, P = 0.035). The display of the drainage directions in the outlet area of the thoracic duct by the two methods showed excellent consistency (kappa value = 0.815) in 12 patients whose outlet areas were visualized by both methods. The degrees of visualization of the upper, middle, and lower segments of the thoracic duct in the NMRTD group were significantly greater than those in the DLG group (P values were 0.02, 0.00 and 0.00, respectively). All 18 patients (100%) showed dilatation of the lymph vessels in the pelvic cavity and retroperitoneum on abdominopelvic MR and DLG as well as pelvic perineal reflux or leakage on DLG. MR revealed multiple-site abnormalities that could not be detected by DLG, including multiple long T1 and long T2 lesions of the spleen in 8 patients (44.4%), of the subcutaneous in 7 patients (38.9%), of the bone in 6 patients (33.3%), perineal lymphedema in 18 patients (100%), and abdominopelvic effusion in 10 patients (55.6%).ConclusionNMRTD combined with abdominopelvic MR has advantages in comprehensively evaluating the thoracic duct and multiple systemic abnormalities in patients with chylous leakage of the female reproductive system.

Gastropods have an important ecological role in coastal ecosystems, such as decomposing organic matter, playing an important role in the food chain and with the characteristics of the habitat at the bottom of the substrate, this organism is used as a bioindicator to assess the quality of the marine environment. The importance of initial documentation of the types of marine biota in an area needs to be done, one of which is on Amor-amor Beach where this area is the center of the development of aquaculture activities in the North Lombok area. This study aims to identify the types of gastropods in the intertidal zone of Amor-Amor Beach, North Lombok Regency. This type of research is descriptive exploratory. The study was conducted in July - September 2024. Sampling by purposive sampling consisted of three stations, namely; station 1 (waters facing the Tambak inlet), station 2 (waters in the outlet area) and station 3 (waters far from the tambak area). The sampling used a 1x1 m transect, species attached to rocks were taken directly, while species that burrowed or were in the sand substrate were taken by placing a PVC pipe frame with a sieve. Species of unknown type were put into a sample bottle given a 70% alcohol solution, then identified using an identification book and several internet literature. The results of this study found 23 species of gastropods from 13 families, namely the Neritidae family (4 species), the Muricidae family (2 species), the Conidae family (5 species), the Nassaridae family (4 species), the Strombidae family (2 species) and 1 species for each of the Collumbelidae, Olividae, Littorinidae, Cypraeidae, Ranelidae, Nacelidae, Turbinidae, and Trochidae families. This finding is important as a basis for information for biodiversity conservation efforts and as an ecological indicator in coastal environmental biomonitoring activities.

To study the spatio-temporal distribution characteristics and sources of dissolved organic matter （DOM） in different types of lakes, water samples were collected from the Wuliangsuhai Lake, Daihai Lake, and Nanhai Lake in Inner Mongolia in April and July 2023. The spectral characteristics and composition of DOM in the three lakes were analyzed using UV-vis spectroscopy, 3D fluorescence spectroscopy, and parallel factor analysis. Additionally, the response of DOM to water quality factors was explored. The results showed that the Daihai Lake had the highest DOM content among the three lakes. Compared to that during spring, the average concentration of dissolved organic carbon （DOC） during summer in the Wuliangsuhai Lake, Daihai Lake, and Nanhai Lake increased by 69.57%, 14.68%, and 85.88%, respectively. Additionally, the highest concentration of DOC in the Wuliangsuhai Lake increased from 15.32 mg·L-1 in the northern region during spring to 25.73 mg·L-1 in the central region during summer. The highest DOM concentration in the Daihai Lake was in the central region during spring with 56.12 mg·L-1 DOC but in the western region during summer with 64.12 mg·L-1 DOC. In the Nanhai Lake, the DOM in the inlet area was higher during spring, whereas it doubled in the outlet area during summer. Moreover, DOM in the Wuliangsuhai Lake showed the highest aromaticity and hydrophobicity, but lowest values were found in the Nanhai Lake. In addition, the humus of the three lakes mainly comprised fulvic acid. As for source, DOM was mainly endogenous during spring and exogenous during summer in the Wuliangsuhai Lake, while it was endogenous in the Daihai Lake and Nanhai Lake. Furthermore, the exogenous characteristics of DOM in the Daihai Lake were enhanced, while the endogenous characteristics of DOM in the Nanhai Lake were enhanced from spring to summer. Significant correlations were observed between DOM and TN, TP, and DO in the three lakes. The increase in TN, TP, and Chl-a in the Wuliangsuhai Lake and TN, TP, and COD in the Daihai Lake weakened the endogenous characteristics of DOM, whereas the increase in TN, Chl-a, DO, and COD in the Nanhai Lake enhanced the endogenous characteristics of DOM. The seasonal variation of spatial distribution and sources of DOM in different types of lakes were markedly influenced by hydrological conditions, external water input, biological activities, and human impacts.

A new approach automatically calculating the outlet and upper catchment area of alpine glacial lakes