Didarul Islam

Vertical container-type smart farms offer an effective way to improve productivity in space-limited environments, but their multi-layer arrangement often creates stagnant airflow and nonuniform microclimates. In this study, computational fluid dynamics (CFD) and the Taguchi method were combined to optimize the layout of air-conditioning components in a container-type strawberry smart farm. Three spatial design factors were considered: inlet position, outlet position, and carbon dioxide (CO2) nozzle position. Nine cases were constructed using a three-level L9 orthogonal array, and spatial standard deviation was used as the uniformity index for temperature, CO2 concentration, and local mean age of air (LMA). The baseline model showed low-velocity and recirculation regions around the cultivation beds and structural frame, producing substantial nonuniformity in CO2 distribution. The middle layer had the highest mean CO2 concentration, whereas the lower layer had the lowest concentration, with a maximum interlayer difference of 53.7 ppm. The Taguchi analysis showed that outlet position was the most influential factor, with a delta value of 8.74 and a contribution ratio of 57.78%. The optimal configuration placed the inlet at 1,200 mm, the outlet at 1,500 mm, and the CO2 nozzle at 1,200 mm. Compared with the baseline model, this configuration reduced the standard deviation of CO2 concentration from 75.85 to 7.08 ppm and improved the standard deviation of LMA from 5.63 to 4.98 s. However, temperature uniformity slightly decreased as the analysis used steady-state conditions, fixed operating flow rates, and a simplified crop geometry; the optimal layout should be revalidated when the container size, crop canopy density, or operating strategy changes. These results demonstrate that spatial microclimate uniformity in multi-layer container-type strawberry smart farms can be improved efficiently by optimizing component layout.

Obstructive sleep apnea (OSA) is a serious medical condition typically diagnosed through polysomnography, consequently incurring economic and time burdens on patients. Although diagnosis based on computational fluid dynamics is available, it is limited owing to high computational costs and reliance on expert knowledge. To address these challenges, we propose a Koopman operator-based reduced-order model (ROM) incorporating nonlinear embeddings via convolutional autoencoders. The developed model is intended to explore the feasibility of supporting OSA-related analysis in computed tomography images of the upper-airway. This model advances dynamics in a latent space through a single Koopman operator layer and leverages techniques—such as the reparameterization trick and β-variational-autoencoder warm-up—as well as novel loss functions and eigenvalue penalty terms to facilitate stable prediction. Comparative evaluations indicate that the proposed model can substantially reduce dimensionality and computational cost while showing improved accuracy relative to conventional data-driven ROMs within the considered experimental setting. Under moderate noise conditions, the model demonstrates increased robustness in the tested scenarios. Furthermore, the proposed method demonstrates the potential to predict novel diagnostic indicators such as breathing diagram and power, which are critical for OSA assessment. Overall, this study establishes a foundation for an accurate and efficient deep learning-based OSA diagnosis.

Pseudoaneurysm forms as a sac from arterial wall damage due to percutaneous procedures and poses a high risk of rupture if untreated. Ultrasound-guided thrombin injection (UGTI) is the most common minimally invasive treatment, which specifically involves the interaction between injected thrombin and plasma fibrinogen. This study presents the development of a thrombin-induced thrombosis model within a computational fluid dynamics framework to simulate thrombus formation in plasma. The model was applied to pseudoaneurysms with complex geometries, including sac diameters greater than 20 mm, neck widths exceeding 10 mm, or neck lengths shorter than 5 mm. By varying injection parameters such as location, duration, and dosage, we evaluated procedural outcomes based on two clinical indicators: technical success and treatment success. The analysis revealed that injection times shorter than 5 s were associated with lower treatment success rates, indicating reduced procedural safety. In contrast, injection durations of 8 s or longer led to improved technical and treatment outcomes. Additionally, treatment success was more consistent when the thrombin dose approached 500 IU. However, in pseudoaneurysms with neck widths over 10 mm, increasing the thrombin dose caused excessive fibrin leakage outside the sac. To ensure both the safety and effectiveness of UGTI procedures, it is clinically recommended to maintain an injection time of at least 8 s, limit the thrombin dose to 500 IU or less, and target the center of the pseudoaneurysm sac for injection.

Submersible drainage pumps are widely used in various applications, including irrigation and drainage, municipal wastewater projects, and sewage pumping. These pumps are suitable for handling mixtures consisting of solid–liquid components and have sophisticated two‐phase flow characteristics and wear mechanisms. Therefore, the operational stability of submersible pumps is essential when transporting solid–liquid mixtures. This work aims to optimize existing pumps and enhance hydraulic performance via the computational fluid dynamics (CFD) software ANSYS‐CFX. The test pump performance data were compared with the computational data to validate the pump model. The study revealed that altering the shape of the impeller hydraulic performance could improve by 4%, significantly reducing the erosion wear effects. Additionally, optimizing the casing shape could increase the efficiency by 4–5%, although practical implementation is challenging and improves the anti‐wear erosion effects. The effects of the particle concentration and particle size were investigated and discussed under different operating conditions for various shape change models. The erosion rate increased with increasing particle concentration at both the leading and trailing edge of the impeller blades. Altering the pump's impeller can minimize the average erosion rate by at least 20%. The revised model significantly reduced erosion wear on the impeller blades.

Optimizing the hydraulic efficiency of submersible drainage pumps (SDPs) is crucial for energy conservation and performance enhancement, especially in emergency applications. Therefore, this study aims to develop an energy-efficient SDP by designing an optimized impeller model using a numerical scheme and introducing a flow balance block (FBB) as an alternative to modifying the pump casing, thereby reducing internal space and improving performance. Experimental validation of the optimized impeller and FBB was conducted by comparing their performance with the original pump model. The results demonstrated that the optimized impeller increased efficiency by 3.35% at a flow rate of 0.195 m3/min, with an overall average efficiency improvement of 2.33%. Additionally, when the optimized impeller and FBB were combined, the pump's efficiency was further enhanced by 5%, and the flow rate increased by approximately 10%. The study also proposed that the tap bolt method is more effective for installing the FBB than the silicone attaching method. This research provides a comprehensive experimental approach to improving SDP efficiency and offers valuable insights for future pump optimization.

This review aims to provide a detailed analysis of the synthesis methods, properties, and applications of natural fiber‐reinforced epoxy composites, highlighting their potential as sustainable materials for various industries. The objective of the study is to examine how different natural fibers such as jute, flax, hemp, and sisal impact the mechanical performance of epoxy composites. The synthesis of these composites involves fiber selection, surface treatments, and epoxy matrix formulation, with processing techniques like hand lay‐up, vacuum infusion, and compression molding playing critical roles. Quantitative results show that tensile strengths of these fibers range from 12 MPa (abaca) to 1627 MPa (pineapple), and densities range from 295 kg/m³ (kenaf) to 1560 kg/m³ (pineapple), reflecting their variability and influence on composite performance. The review finds that fiber‐matrix compatibility, fiber orientation, and interfacial adhesion significantly affect the mechanical properties, such as tensile strength and thermal stability. The composites demonstrate potential applications in the automotive, aerospace, and construction industries, where they can be used for interior components, structural elements, and non‐load‐bearing parts. The study concludes that natural fiber‐reinforced epoxy composites offer a promising solution for reducing environmental impact while maintaining material performance in various structural applications.Highlights: Epoxy‐reinforced natural fiber composites synthesis and applications. Synthesis involves fiber selection, treatment, and epoxy matrix formulation. Natural fibers like jute, flax, hemp, and sisal used due to their renewable nature and biodegradability. Applications include automotive and furniture industries.

Several studies have investigated predictive factors such as morphological, physiological, and fluid dynamics perspectives for obstructive sleep apnea (OSA) using computed tomography imaging, computer simulations, and experiments. Computational fluid dynamics is used in this study to analyze airflow in the upper airway across different body mass index (BMI) groups to identify suitable factors for predicting OSA. A comparative analysis is conducted on three groups: normal BMI (22.8 ± 1.0), overweight BMI (31.8 ± 1.5), and OSA (28.6 ± 3.3), with nine participants in each group. Geometric parameters were analyzed in addition to fluid dynamics factors. A comparison of the geometric variables revealed that the OSA group had the shortest total airway length (1.5 × 10−1 m) and the smallest volume (5.4 × 10−5 m3). However, t-test results showed low statistical significance for these differences. For fluid dynamics variables, the OSA group experienced the highest pressure drop (−46.8 Pa) and the highest adjusted pressure coefficient (Cp = 0.88) compared to the other two groups. From the analysis of breathing diagrams, the OSA group exhibited the largest area under the breathing power curve (32.6 × 10−3 N m/s) followed by the normal weight (24.9 × 10−3 N m/s) and overweight (21.0 × 10−3 N m/s) groups in descending order. Analysis of fluid dynamics factors indicated that the OSA group exhibited significantly higher pressure drop and pressure coefficient values compared to other groups although the differences between the groups were less significant. Finally, one key finding from this research highlights a new computational approach that relies on the breathing diagram. This new approach could provide more accurate insights into predicting and managing OSA due to their distinctive shapes.

Submersible drainage pumps are used around the world both residentially and industrially for draining water and sewage. However, these pumps are prone to wear and clogging when the flows inward contain particles and air bubbles, and the combined effects of cavitation and erosion directly affect the performance of such pumps and degrade their efficiency. Therefore, it is essential to design a submersible pump that mitigates the adverse effects of cavitation and erosion. Reported here is an energy-efficient submersible drainage pump for use in emergency response. The combined cavitation–erosion effects are established in order to reduce their adverse impact on the pump, and how erosion wear affects the cavitation characteristics of the water in the pump is investigated. An experiment was conducted to verify the numerical results pump, and then, the influences of particle concentration and size on two-stage existing and altered model submersible pumps were analyzed using computational fluid dynamics. The results show that the performance of the altered model pump increased by 4.34%, with the cavitation–erosion effects reduced significantly. In addition, higher particle concentration induced higher erosion rates at both the leading and trailing edges of the impeller blades. Furthermore, the altered model significantly reduced the cavitation–erosion impact on the pump impeller blades compared to the existing model.

Purpose Commercial double J stents (DJS) have a uniform shape regardless of the specific nature of various ureteral diseases. We tested renovated DJS and compared them with conventional DJS using ureter models. Methods One straight ureter model included stenosis at the distal ureter near the ureterovesical junction and the other did not. We used conventional DJS and renovated 5- and 6-Fr soft DJS for ureter stones and 6-, 7-, and 8.5-Fr hard DJS for tumors. The DJS comprised holes in the upper, middle, or lower one-third of the shaft (length, 24 cm; 2-cm-diameter coils at both ends). More holes were created along the shaft based on the ureteral disease location. Conventional DJS had holes spaced 1 cm apart along the shaft. Renovated DJS had holes spaced 1 cm apart along the shaft with 0.5-cm intervals on the upper, middle, or lower one-third of the shaft. Urine flow was evaluated. Results As the DJS diameter increased, the flow rate decreased. The flow rates of DJS with holes in the lower shaft were relatively lower than those of conventional DJS and DJS with holes in the upper and middle shafts. In the ureter model without stenosis, 6-, 7-, and 8.5-Fr renovated stents exhibited significantly higher flow rates than conventional stents. In the ureter model with stenosis, 5-, 6-, 7-, and 8.5-Fr renovated stents did not exhibit significantly higher flow rates than conventional stents. Conclusion Renovated stents and conventional stents did not exhibit significant differences in urine flow with stenosis.