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High-pressure pump rotors are critical components in a wide range of industrial and mechanical systems, including turbomachinery, hydraulic systems, and aviation engines. This study presents a dynamic model for a single-stage high-speed high-pressure centrifugal pump supported by hydrodynamic journal and thrust bearings. The model is based on a rigid rotor framework and incorporates the coupling effects between the journal and thrust bearings. The influence of key bearing parameters is systematically investigated, with particular attention given to the impact of introducing a central groove in the left bearing. Furthermore, the analysis explores the effects of integrating a third central journal into the system which acts also as rear wear ring. The study also examines the role of bearing boundary conditions, which can be regulated through auxiliary lines, and evaluates the influence of unbalance forces on system performance. The results demonstrate that boundary conditions significantly affect the load-carrying capacity and stability of the bearings, potentially leading to bearing failure if not properly managed. Additionally, while a coupling effect between the journal and thrust bearings is observed, its influence is found to be relatively minor in the context of the rigid rotor model employed in this analysis. The findings of this study provide valuable insights for the design and optimization of high-speed centrifugal pumps, offering a deeper understanding of the dynamic interactions and operational constraints inherent in such systems.

Streptococcus pyogenes infection in Nile tilapia causes high mortality and economic loss. This study evaluated the efficacy of a formalin-killed S. pyogenes bacterium loaded on nano-selenium (nano-vaccination) to prevent streptococcal disease outbreaks on farmed tilapia. 120 Nile tilapia fingerlings were allocated into 4 groups: control group: was injected with 0.1mL of normal saline without any challenges, infected group: was injected with 0.1mL of 1 × 10 7 (CFU)mL − 1 , nano-vaccine group: was injected with two doses of nano-vaccine with an interval of 21 days until day 32nd and nano-vaccine bacteria group: was injected with two doses of nano-vaccine then challenge with bacteria after day 32nd. Hematological biomarkers, inflammatory, oxidative stress, antioxidant enzymes, and histology were estimated in the liver. The selenium nano-vaccinated group showed significant improvement in hematological profiles and elevated antioxidant enzyme activity compared with the control. Compared to the unvaccinated fish, the vaccinated fish showed an enhancement in antioxidant capacity and hematological stability after bacterial challenge. In contrast, infected fish showed higher oxidative stress and inflammatory indicators. Selenium nano-vaccination enhanced hematological performance, antioxidant defense, and immune response in Nile tilapia, allowing effective protection against S. pyogenes infection with minimal inflammation and oxidative damage.

Water hammer (WH) is a phenomenon characterized by the rapid opening or closing of valves or pumps in pipelines, resulting in a disruptive noise, intense vibrations, and potential damage to pipes, fittings, structures, and even human safety. While WH arresters are commonly employed to mitigate this issue in smaller plumbing systems, alternative solutions are required for larger applications like power plants. Researchers have proposed the utilization of pipe materials with a low modulus of elasticity in areas prone to WH events, as these materials possess the capability to absorb a significant portion of the resulting vibrations. This study focuses on investigating the influence of pressure and strain induced by the WH phenomenon. Experimental data collected from measurements using a specially designed test rig, as well as numerical and dimensionless analyses applied to the same rig, are employed to examine this effect. The experimental and numerical investigations encompass a range of flow rates and pressures. Five pipe materials, namely Galvanized steel, Copper, uPVC, PPr, and GRP, were selected for evaluation. The results indicate a deviation between the numerical and experimental results of WH frequency which can be explained from the pipeline rigidity. A Fast Fourier Transform (FFT) analysis was performed to analyze the frequency components of the pressure transients resulting from water hammer events in the different pipe materials. The results indicate that pipe materials with lower elastic modulus, such as PPr and uPVC, exhibit reduced WH effects compared to materials with higher elastic modulus, such as steel. This research highlights the importance of selecting appropriate pipe materials for pressure pipelines in order to mitigate the dangers associated with WH. The results of the FFT analysis revealed distinct frequency responses for each material, illustrating how their unique viscoelastic properties affect the transient behavior.

Ceramic materials are increasingly used in micro-electro-mechanical systems (MEMS) as they offer many advantages such as high-temperature resistance, high wear resistance, low density, and favourable mechanical and chemical properties at elevated temperature. However, with the emerging of additive manufacturing, the use of ceramics for functional and structural MEMS raises new opportunities and challenges. This paper provides an extensive review of the manufacturing processes used for ceramic-based MEMS, including additive and conventional manufacturing technologies. The review covers the micro-fabrication techniques of ceramics with the focus on their operating principles, main features, and processed materials. Challenges that need to be addressed in applying additive technologies in MEMS include ceramic printing on wafers, post-processing at the micro-level, resolution, and quality control. The paper also sheds light on the new possibilities of ceramic additive micro-fabrication and their potential applications, which indicates a promising future.

Newly synthesized vaccines prepared from formalin-killed bacteria Streptococcus pyogenes were investigated in the current study to evaluate the effectiveness of the newly synthesized vaccine as well as their safety by injected intraperitoneal. The study involved several steps 1st step is the preparation of the vaccine followed by the 2nd step: Evaluate the effectiveness and vaccine safety against pathogenic S. pyogenes through 4 different groups including control (Group I). Group II (Bacterial, infected group), Group III (Vaccine), and the Last group was the challenged group after the vaccination (Vacc + Bac). Different Immunological and biochemical parameters were measured in addition to hematological and histopathological examinations. For example, oxidative/antioxidants, inflammatory biomarkers, fragmentation and cell damage, and finally the histopathological study. The current study showed an increase in all oxidative, inflammatory, and cell damage (DNA fragmentation assays), additionally markedly elevation in histopathological cell damage in the infected group (Group II) compared with the control group. The vaccine and challenged after vaccination group (vaccine + Bacteria), showed great improvement in oxidative biomarkers (LPO) and an increase in antioxidants biomarkers (GSH, SOD, GST, DPPH, ABTS, GR and GPx), Also the inflammation and histopathological examination. The newly synthesized vaccine improved the resistance of Oreochromis niloticus and can be used as a preventive therapy agent for pathogenic bacteria S. pyogenes.

The present study investigates the free vibration behavior of rotating beams made of functionally graded materials (FGMs) with a tapered geometry. The material properties of the beams are characterized by an exponential distribution model. The stiffness and mass matrices of the beams are derived using the principle of virtual energy. These matrices are then evaluated using three different beam theories: Bernoulli–Euler (BE) or Classical Beam Theory (CBT), Timoshenko (T) or First-order Shear Deformation Theory (FSDT), and Reddy (R) or Third-order Shear Deformation Theory (TSDT). Additionally, the study incorporates uncertainties in the model parameters, including rotational velocity, beam material properties, and material distribution. The mean-centered second-order perturbation method is employed to account for the randomness of these properties. To ensure the robustness and accuracy of the probabilistic framework, numerical examples are presented, and the results are compared with those obtained through the Monte Carlo simulation technique. The investigation explores the impact of critical parameters, including material distribution, taper ratios, aspect ratio, hub radius, and rotational speed, on the natural frequencies of the beams is explored within the scope of this investigation. The outcomes are compared not only with previously published research findings but also with the results of 3-Dimensional Finite Element (3D-FE) simulations conducted using ANSYS to validate the model’s effectiveness. The comparisons demonstrate a strong agreement across all evaluations. Specifically, it is observed that for thick beams, the results obtained from FSDT and TSDT exhibit a greater agreement with the 3D-FE simulations compared to CBT. It is shown that the coefficient of variation (C.O.V.) of first mode eigenvalue of TSDT, FSDT and CBT are approximately identical for random rotational velocity and discernible deviations are noted in CBT compared to FSDT and TSDT in the case of random material properties. The findings suggest that TSDT outperforms FSDT by eliminating the need for a shear correction coefficient, thereby establishing its superiority in accurately predicting the natural frequencies of rotating, tapered beams composed of FGMs.

We formulate a variational constitutive framework that accounts for nonlinear viscous behavior of electrically sensitive polymers, specifically Dielectric Elastomers (DEs), under large deformation. DEs are highly viscoelastic and their actuation response is greatly affected in dynamic applications. We used the generalized Maxwell model to represent the viscoelastic response of DE allowing the material to relax with multiple mechanisms. The constitutive updates at each load increment are obtained by minimizing an objective function formulated using the free energy and electrostatic energy of the elastomer, in addition to the viscous dissipation potential of the dashpots in each Maxwell branch. The model is then used to predict the electromechanical instability (EMI) of DE. The electro-elastic response of the DE is verified with available analytical solutions in the literature and then the material parameters are calibrated using experimental data. The model is integrated with finite element software to perform a variety of simulations on different types of electrically driven actuators under various electromechanical loadings. The electromechanical response of the DE and the critical conditions at which EMI occurs were found to be greatly affected by the viscoelasticity. Our model predicts that under a dead load EMI can be avoided if the DE operates at a high voltage rate. Subjected to constant, ramp and cyclic voltage, our model qualitatively predicts responses similar to the ones obtained from the analytical solutions and experimental data available in the literature.

Studying rotor-bearing systems involving fluid film bearings is essential for designing and assessing the dynamic responses and performance of rotating machinery. They are involved in many applications such as pumps, turbines, and engines. Water-lubricated bearings are often used in many applications where the use of oil-based lubricants is not desirable, such as in environmentally sensitive areas such as water desalination. In this study, dynamic analysis is performed to identify the stability regions that prevent the application of water-lubricated journal bearings. This is achieved by solving the system equations of motion and then using an infinitesimal perturbation method to evaluate the second-order bearing coefficients of a journal bearing. In this paper, a steel shaft supported by two symmetrical journal bearings was used to investigate the system stability analysis. A test rig is designed and manufactured to examine the rotor’s dynamic behavior and verify the theoretical outcomes of the FE model, utilizing the bearing coefficients based on second-order analysis. Furthermore, this study compares the two fluids, both theoretically and experimentally, investigating their impact on the rotor-bearing system at different rotational speeds. The theoretical findings indicate that the threshold speed for journal bearings is significantly higher when using water as the lubricant fluid film compared to using oil as the lubricant fluid. Additionally, because of the low viscosity of water, water-lubricated bearings are susceptible to significant wear and noise in operating conditions. Our experiments show that an oil lubricant provides less response than a water lubricant for unbalanced rotors within the tested speed range.

The present study was carried out to evaluate the use of Biogen and sodium butyrate (SB) as feed additives in the diet of Nile tilapia (Oreochromis niloticus) fingerlings, in two parallel experiments. Biogen was incorporated in isonitrogenous (35% crude protein) and isocaloric (19 MJ kg−1) diets at four levels (0.0 (control), 0.5, 1.0, and 2.0%), while SB was included at five levels (0.0 (control), 0.5, 1.0, 2.0, or 3.0%). The diets were fed to fingerling Nile tilapia (10.5 ± 0.5 g) at a daily rate of 4% of their body weight, three times a day, for 60 days. Except the lymphocytes and monocyte numbers in fish fed SB, hematological parameters, including red blood cell (RBC) hematocrit (Ht), hemoglobin (Hb), and white blood cells (WBC) were not significantly (P > 0.05) affected by dietary Biogen and SB. The lymphocytes number in Nile tilapia fed on SB increased with increasing SB up to 2% level, and decreased afterwards. Monocyte numbers showed irregular patterns. The activities of serum enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of fish fed diets containing Biogen or SB were not significantly affected by dietary treatments (P > 0.05). No structural differences of tilapia liver were detected between all Biogen treatments and sodium butyrate concentrations up to 1% with control. At concentrations of 2 and 3% sodium butyrate, liver steatosis increased leading to shrinked acentric nuclei. At a concentration of 2% Biogen, some glomerulus cells had fading cytoplasm. Concerning fish fed SB diets, the structure of kidney was the same as in control except at concentration of 3% SB, where the septum between cells disappeared. No changes in gill structure were noticed at all concentrations of Biogen and SB.

As a solid-state welding technique, friction stir welding (FSW) has many advantages over conventional fusion welding. Its applications in the manufacturing and joining of parts in aerospace, automotive, and shipbuilding have significantly increased. Friction heat generation is the fundamental driver of the FSW process. It governs material flow, microstructural evolution, mechanical properties, and residual stresses. Understanding the effect of heat generated on the joint quality is essential for process parameter optimization, ensuring defect-free welds and high-quality joints. Thus, evaluating the thermal history of the FSW process is a key requirement for effective analysis. This comprehensive review critically discusses research studies published over the past three decades (1991–2025) that have examined different approaches to predict and measure heat generation in FSW. A total of 136 highly relevant articles were selected from the Scopus database and systematically analyzed. The effects of various welding parameters on heat generation, microstructural evolution, and joints’ mechanical properties have been reported. Different heat generation prediction and measurement techniques, such as analytical models, finite element models (FEM), and experimental methods have been discussed in terms of their feasibility, accuracy, advantages, disadvantages, and cost. The evolution, state of the art of analytical models and FEM over the last three decades are analyzed and future research directions are outlined. Finally, the correlation between process parameters, heat generated, microstructural development, and mechanical performance of the welded joints for various workpiece materials is investigated. This review provides a critical and comparative perspective that highlights the strengths and limitations of each method, offering practical guidance for researchers and industry practitioners.