Outlet Area Research Articles

The application of non-enhanced magnetic resonance thoracic ductography combined with magnetic resonance abdominopelvic scanning in the diagnosis of chylous leakage of the female reproductive system

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.

Seasonal Variation in DOM Spectral Characteristics and Sources in Different Types of Lakes

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

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

A comprehensive investigation of the occurrence and speciation of arsenic in the water, sediments and aquatic products in Dongping Lake, an important drinking water source in East China.

The total arsenic (TAs), inorganic arsenic (iAs) including arsenate (As(V)) and arsenite (As(III)) distribution in water, surface/core sediments and aquatic products in Dongping Lake was investigated. The pollution levels and associated risks were evaluated using the methods of geoaccumulation index, single factor index, health risk model and potential ecological risk index. The results showed that As(V) dominated across all environmental matrices. TAs concentrations in water (1.36-3.90μg/L) were all below the threshold set by the World Health Organization (10μg/L). The average concentrations of As(V) and As(III) in water were 0.82 0.48μg/L and 0.28 0.31μg/L, respectively, while those in surface sediments were 7.30 2.58mg/kg and 1.16 0.38mg/kg. Laohu Wharf, the Dawen River inlet and the northern outlet area were identified as hot spots for elevated arsenic levels in water and surface sediments. In core sediments, the maximums were detected at a depth of 1-2cm or 2-3cm. As(V) and As(III) in water were significantly correlated with dissolved organic carbon, Chla, dissolved inorganic nitrogen and pH. As(V) in sediments were closely associated with oxidation-reduction potential, organic carbon and total nitrogen. Shellfish had significantly higher TAs and iAs levels compared to fish and shrimp. Collectively, shellfish and fish had been polluted with iAs. The average carcinogenic risks caused by iAs through daily intake of shellfish (3.72 10-4/a) exceeded the acceptable level (10-4/a). The TAs pollution in sediments was at a slight to moderate contamination level and posed a considerable ecological risk.

Analysis and identification of the temperature field of dam leakage based on infrared thermal imaging

Leakage is the most common issue encountered in earth–rock dam projects, with characteristics of strong concealment in the initial stage and rapid development and significant threat in the later stage. For a rapid and accurate detection of leakage in earth–rock dams, this paper introduces an infrared thermal imaging technology by fully considering the correlation between dam leakage and temperature. The principle behind the application of this technology for the noncontact detection of water leakage in earth–rock dams was expounded. Based on the theory of flow–heat coupling and combined with a numerical simulation test on the leakage detection of earth–rock dams under the effects of varying water heads and water–air temperature differences, the feasibility of the infrared thermal image technology in detecting leakages in these dams was verified, and the infrared image characteristics of leakage outlets in the dam and their influencing rules were thoroughly analyzed. The results showed that the leakage in the earth–rock dam led to low-temperature anomalies in the leakage outlet area. With the increase in the water air temperature difference and water head, these low-temperature anomalies became increasingly evident. The temperature and water head of the leakage outlet showed a decreasing trend that could be characterized by a quadratic polynomial. The infrared images captured by the UAV could vividly and intuitively present the temperature anomalies caused by leakage, manifesting as a temperature stratification phenomenon with low values inside and high values outside. The temperature measurement accuracy of an infrared thermal imager is positively correlated with reflectivity in a linear manner, whereas it is negatively correlated with the detection distance. Additionally, with an increase in the angle between the focal plane of the infrared thermal imager and the normal direction of the soil dam surface, the temperature measurement accuracy decreases. The development of an unmanned aerial vehicle utilizing the proposed technology for leakage detection in earth–rock dams, along with the identification of abnormal temperature fields indicative of leakage on the dam surface, holds significant importance. This technology contributes to the rapid and accurate detection of leakage hazards, ensuring the safety of earth–rock dam engineering projects.

A choice of sluice passage for a tidal power plant: venturi- or culvert-type passage?

The objective of this study was to investigate which of the two most common sluice passage types (i.e. culvert- and venturi-type passages) for a tidal power plant has a better discharge capacity. The discharge capacity of sluice passages was estimated using computational fluid dynamics (CFD) code Flow-3D. The total flow rate through sluice passages (and resultant power output) was further investigated and compared using 0-D modelling in a case study of the Taedong barrage, the DPR Korea. The results of CFD and 0-D modelling indicated that a culvert-type passage showed superior discharge capacity and resultant power output over a venturi-type passage in the case that the outlet area of the two passages was the same. In this case, therefore, the number of venturi-type passages required for the target power generation will be significantly increased, which will result in an increase in the complexity and cost of the construction and operation for the tidal power plant. In summary, it can be concluded that the results obtained in this study will help researchers to choose carefully sluice passage types to improve the discharge capacity and the resultant power output for tidal range power plants.

OPTIMIZATION OF THE RECEIVING BUNKER OPERATION DURING THE BLOCKING OF BULK MATERIALS

The article discusses an urgent problem that significantly affects the efficiency of concrete mixing enterpris-es - the formation of vaults in receiving bunkers. This phenomenon leads to unpredictable shutdowns of the production process, reduced equipment productivity and increased maintenance costs. The analysis of mod-ern methods of dealing with the vault showed their limited effectiveness. Vibration and pneumatic systems, which are widely used today, are not always able to completely eliminate the problem, especially when changing the properties of bulk materials or the geometric parameters of hoppers. In order to increase the reliability and performance of concrete mixing plants, a new approach has been proposed, which involves the use of a special ripper. This device is equipped with mechanical elements that allow you to effectively de-stroy the vault in the area of the hopper outlet, ensuring a continuous flow of material. The introduction of a special ripper at concrete mixing plants will improve the quality of finished products, reduce the cost of pro-duction and ensure the stable operation of the enterprise. The results obtained can be used to optimize the design of receiving bins and develop new technologies for processing bulk materials.

The influence of openings on thermal comfort in the residential units of Sub-Communal RISHA, Mojo Surakarta

Abstract Temporary Housing Sub-Communal RISHA (Healthy Simple Instant House) is a temporary housing facility located in Surakarta, one of the housing development solutions for slum settlements. Sub-Communal RISHA was built to provide housing for residents affected by the development of the Bengawan Solo Riverbanks. This study was conducted to identify the effect of openings on the thermal comfort of the space in residential units and provide a recommendation to improve thermal comfort as an adaptation to environmental conditions affected by global warming. With a relatively small residential unit area, thermal comfort is essential so that residents remain comfortable in their activities and the house becomes healthier. The method combines observation, field measurements, and simulations using CFD (Computational Fluid Dynamic) software. The study results stated that thermal comfort in residential units in Sub-Communal RISHA is in the uncomfortable category. This condition can lead to health issues and reduced productivity, where openings affect the flow of wind entering the room by placing the inlet and outlet, not facing each other, at different elevations, and the outlet area is larger than the inlet.

Investigation on the suitability of conventional film hole under pulsed detonation incoming flow conditions

Investigation on the suitability of conventional film hole under pulsed detonation incoming flow conditions

Nozzle structure optimisation in a photovoltaic irrigation system

AbstractOn the basis of the significant impact of the sprinkler nozzle structure in photovoltaic irrigation systems, the nozzle parameters are optimised to improve sprinkler adaptability and irrigation uniformity under different light intensities. An experimental test and numerical simulation were conducted to analyse the influence of nozzles with distinct parameters on the spray irrigation effect. Taking the irrigation uniformity coefficient as the optimisation goal and the nozzle outlet shape, outlet area and straight flow channel length as the optimisation variables, an orthogonal experimental design was employed, and the optimal solution was obtained via range analysis. The experimental results indicate that the sprinkler performs best when the outlet shape is circular, the nozzle outlet area is 7 mm2 and the flow channel length is 2 mm. The optimal nozzle characteristics were tested and compared with those of the original design, and numerical simulation was used to demonstrate the optimised internal flow mechanism. The results demonstrate that the optimised flow rate and spray range are improved, and the working pressure and rotation period are significantly reduced, enabling the system to adapt to a more extensive range of light intensities. The radial water distribution structure is better, and the combined application rate and uniformity coefficient are also significantly improved. In addition, the sprinkler outlet speed is more consistent, and the area of the high‐speed zone in the spray plate increases, which is conducive to reducing energy loss and enhancing sprinkler irrigation uniformity.

An innovative hollow-cable dome structure for indoor cooling

An innovative hollow-cable dome structure for indoor cooling

An Automated Geometric Analysis and Characterization of an Oil-Lubricated Twin-Screw Compressor for Predictive Modeling

Abstract Compressor manufacturing companies are showing a growing interest in the development of validated compressor simulation models capable of predicting the behaviour of the machine if subjected to appropriate modifications. A validated predictive model of the entire compressor is useful for analysing the influence of the variation of some fundamental parameters, such as the variation of volumes or new inlet and outlet sections, on the behaviour of the machine. To create these models, geometric parameters such as the variation in volumes, the variation in inlet and outlet sections and the presence of leakage or blowhole phenomena must be provided as input. The precision of these geometric parameters is of fundamental importance for the correct operation of the model and subsequent design analyses. In this work, the authors analysed the complete geometry of an oil-lubricated twin-screw compressor. In particular, an automated calculation methodology was developed using CAD software capable of defining the characteristic curves of the volumes and areas of the compressor: starting from the geometries of the rotors and the stator case, the fluid volumes delimited at the bottom by the rotors and at the top by the case were defined through a Boolean subtraction operation. Subsequently, the volumes that complete the compression phase together were isolated and, through an automatic kinematic analysis with steps of 5° of rotation, starting from the zero reference (null volumes), the characteristic curves of the volumes and inlet and outlet areas were defined through the use of special virtual sensors. The passage sections of the leakage and blowhole leaks were defined in the same way. Particular attention was paid to the analysis of leakage and blowhole phenomena, the presence of which determines a reverse flow of part of the mass flow rate of air during the compression phase, resulting in a decrease in volumetric efficiency. Knowledge of this data is of fundamental importance for the subsequent creation of the 1D/0D model.

Analysis of Flow Loss Characteristics of a Multistage Pump Based on Entropy Production

To reveal the internal flow loss characteristics of a multi-stage pump, the unsteady calculation of the internal flow field of a seven-stage centrifugal pump was carried out, and the entropy production theory and Q criterion were utilized to analyze the unsteady flow characteristics of each flow component under different flow rates. The research results show that as the flow rate increases, the entropy production value and the energy loss inside the flow components also increase accordingly. The viscous dissipation entropy production caused by fluid viscosity is very small, and the turbulent dissipation entropy production caused by turbulent fluctuations and wall dissipation entropy production are the main sources of energy loss. The impellers, diffusers, and outlet chamber are the main regions of energy loss in the multistage pump. The entropy production value of the first-stage impeller is significantly higher than that of other impellers, while the entropy production value of the first-stage diffuser is significantly lower than that of other diffusers. Through vortex structure analysis, it is found that the high entropy production regions in the impeller are concentrated in the impeller inlet area, the blade suction surface, and the impeller outlet area.

Transient flow and noise characteristics of vortex-turbulence-noise interaction in centrifugal pump

Centrifugal pump operation noise is an avoidable common phenomenon in engineering practices, and its characteristics are closely influenced by the flow characteristics of the fluid. In this paper, a numerical simulation of centrifugal pump operation with different flow rates is carried out using the detached eddy simulation turbulence model and compared with the experimental results. Then the noise source and far-field radiated noise characteristics of the centrifugal pump are investigated using Lighthill’s analogy. The results show that the noise of centrifugal pump is closely related to the flow characteristics of impeller, especially the generation and development of vortex. The relationship between turbulent kinetic energy (TKE) and vortex is complex, involving the generation, development and shedding of vortex. The influence of flow rate variation on vortex structure in impeller is studied by vortex transport equation. It is found that the relative vortex stretching (RVS) term is the main driving force of vortex distribution. The distribution of the Coriolis force (CORF) term is mainly concentrated in the inlet and outlet areas of the flow channel, which is related to the rotational motion of the impeller and the dynamic characteristic of the fluid. The power spectral density inside the impeller is mainly concentrated in the low frequency region, indicating that the low frequency noise component is dominant in energy. The directivity curve of far-field noise pressure level is influenced by hydrodynamic effect, impeller rotation direction and pump design structure, and will have a certain deviation. The spectral curve analysis of velocity, vorticity, pressure and sound pressure level shows that these physical quantities have strong correlation on the spectrum, in which the low frequency component is large, and the high frequency component is complex and volatile.

Systemic investigation of pelvimetric profile in three strains of Deoni cattle

The present research work was designed to establish baseline data of the pelvimetric profile in Deoni Cattle. Deoni cattle (270) of three strains, i.e. Wannera, Balankya and Shevera were selected and divided into six age groups: Group I (12 to 24 months), II (25 to 36 months), III (37 to 48 months), IV (49 to 60 months), V (61 to 72 months) and VI (73 to 84 months) with 45 animals in each group. Body weight along with different pelvimetric parameters such as distance between two angles of haunch (A), distance between two ischial tuberosities (B), distance between level of croup and hip joint (C) and distance between tuber coxae and tuber ischia (D) were measured to determine the transverse and vertical diameter of pelvic inlet and outlet which were used to calculate pelvic area of inlet and outlet. The pelvic area values for both inlet and outlet showed highly significant differences within groups, but no significant difference was observed between the three strains of each group. From the results of the study, it can be concluded that the pelvic area of Deoni cattle increases with the age and it has significant positive correlation with the parity and body weight. Thus, pelvimetric profile can be used as a marker for selection of young Deoni heifers and cows for breeding purposes to lower dystocia incidences.

Experimental study on the suppression of inlet blockage in rotating detonation combustor by porous-wall

Experimental study on the suppression of inlet blockage in rotating detonation combustor by porous-wall

Методические аспекты анализа факторов, влияющих на испарение газоконденсата при подводных выбросах

The process of evaporation of gas condensate during emergency blowout of an underwater well has been studied insufficiently. The influence of various factors on the size of the zone of intense evaporation of gas condensate during the blowout of a shallow gas condensate well requires detailed consideration. In this paper, the researchers, using mathematical modeling, have analyzed this effect for wells with parameters characteristic of the Russian Arctic region. They have performed the calculations using the SPILLMOD model and the Lagrangian element evolution model. A significant dependence of the gas outlet area size and the gas blowout size on the sea surface on the values of the gas plume involvement parameter in the model has been revealed, and at the same time a weak dependence of the size of the zone of intense evaporation of gas condensate on this parameter. The values of the mass flow rate of gas condensate in the discharge, as well as its fractional composition, have a noticeably greater effect.

RESULTS OF EXPERIMENTAL STUDIES ON THE IMPROVED SEED DELIVERY SYSTEM OF A PNEUMATIC PRECISION SEEDER

The research is dedicated to improving the structural and technological parameters of pneumatic seeders, particularly the seed delivery system in John Deere 90 series seeders. It has been identified that existing designs have shortcomings, especially when using No-till, Strip-till, and Mini-till technologies, leading to uneven seeding and reduced yields. To enhance the efficiency of the crop seeding process, it is necessary to refine the design of the elements within the seed delivery system of the pneumatic seeder, including the seed decelerator, seed channel of the seeder shoe, and seed stabilizer, by employing well-founded structural and technological parameters that ensure precise seeding and by using materials that increase their durability. The goal of the research was to optimize the structural parameters of the seed delivery system by developing and testing a new seed decelerator. Experimental studies were conducted using a laboratory setup that allows for variation in parameters such as air flow speed, seeder movement speed, seed injection speed, and the ratio of outlet areas to the inlet area of the seed decelerator. As a result of the experimental studies, patterns of changes in air flow speed at the seeder shoe outlet, seed flow speed of rapeseed and peas, seeding rate, and accuracy (coefficient of variation) were established depending on the ratio of outlet areas to the inlet area of the seed decelerator, air flow speed at the inlet, seeder movement speed, and seed injection (dosing) speed. The results showed that increasing the air flow speed at the inlet leads to an increase in the flow speed at the outlet, which affects the seeding rate and accuracy. The seeder movement speed and seed injection speed significantly influence the seeding rate but may reduce accuracy. A relationship was established between the number of holes in the seed decelerator (ε), seeder movement speed, and seeding rate, allowing for maximum seeding accuracy. The obtained equations will be used for the automated control system of the seed decelerator damper.

Experimental investigation on heat transfer enhancement of supercritical pressure aviation kerosene in tubular laminar flow by vibration

Experimental investigation on heat transfer enhancement of supercritical pressure aviation kerosene in tubular laminar flow by vibration

(Digital Presentation) Multiscale Modeling of Two-Phase Transport in the Membrane Electrode Assembly of Polymer Electrolyte Membrane Fuel Cells: Effect of Relative Humidity and Temperature

Water management plays an important role in the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs). Achieving enhanced water removal at high current density without membrane dehydration requires an optimal design of the membrane electrode assembly (MEA) and MEA-channel interaction depending on operating conditions. The analysis of two-phase transport is challenged by the wide range of pore sizes found in porous layer assemblies, varying from 1-100 nm in the catalyst layer (CL), 50-1000 nm in the microporous layer (MPL) and 10 µm in the gas diffusion layer (GDL), up to the millimeter-sized channel. In this work, a hybrid multiscale model is presented to describe two-phase transport and performance of a representative unit cell as a function of relative humidity (RH) and temperature [1-3]. A control volume (CV) decomposition is used to represent the multiscale pore space of the GDL, MPL and CL in terms of local effective transport properties (porosity, effective diffusivity, permeability, thermal/electrical conductivity and entry capillary pressure) [4]. The model incorporates a macroscopic continuum formulation for gas flow and species, energy, liquid-phase pressure, water dissolved in ionomer, and electronic and ionic potentials [5]. Liquid water transport is modeled by means of a multi-cluster invasion-percolation algorithm, which is coupled to the macroscopic continuum formulation by the phase-change source term of water (evaporation/condensation). Water clusters with a net condensation rate grow by invading the adjacent dry CV with the lowest entry capillary pressure, while clusters with a net evaporation rate shrink by drying the wet CV of the cluster with the lowest entry capillary pressure. An all-or-nothing invasion law is adopted for saturation in the GDL (one pore per CV), while a macroscopic description in terms of capillary pressure curve at the representative elementary volume scale (REV) is used for the MPL and the GDL (thousands to millions of pores per CV). An example of the saturation distribution in the cathode MEA is shown in Figure 1. Local saturation remains between 0.1-0.4 in REVs of the CL and the MPL, increasing up to 1 in macropores of the GDL. Water condenses preferentially under the ribs and transport by capillary action to the GDL/channel interface, where the water flow is released to the channel. The channel saturation remains low, around 0.1, due to the large gas flow velocity used in the differential cell.[1] P.A. García-Salaberri, Modeling diffusion and convection in thin porous transport layers using a composite continuum-network model: Application to gas diffusion layers in polymer electrolyte fuel cells, 167 (2021) 120824.[2] D. Zapardiel, P.A. García-Salaberri, Modeling the interplay between water capillary transport and species diffusion in gas diffusion layers of proton exchange fuel cells using a hybrid computational fluid dynamics formulation, J. Power Sources 520 (2022) 230735.[3] P.A. García-Salaberri, Effect of thickness and outlet area fraction of macroporous gas diffusion layers on oxygen transport resistance in water injection simulations, Transp. Porous Media 145 (2022) 413-440.[4] P.A. García-Salaberri, I.V. Zenyuk, A General-Purpose Tool for Modeling Multifunctional Thin Porous Media (POREnet): From Pore Network To Effective Property Tensors, Heliyon (2023), submitted.[5] P.A. García-Salaberri, A. Sánchez-Ramos, A numerical analysis of the effect of layer-scale and microscopic parameters of membrane electrode assembly in proton exchange fuel cells under two-phase conditions, J. Power Sources (2023), accepted. Figure 1. Saturation distribution in the cathode MEA of a PEMFC operated at 70 oC and RH=0.95 at high stoichiometric conditions. The current density is I=0.5 A cm-2.- Figure 1