Search Results (1,504)

Centrifugal pumps (CPs) are widely utilized in many different industries, and their operations are maintained by their reliable performance. CPs’ most common faults can be categorized as mechanical or flow-related faults: the first ones are often associated with damage at the impeller, while the second ones are associated with cavitation. It is possible to use computational algorithms to monitor both failures in CPs. In this study, two different problems in pumps, the defective impeller and cavitation, have been considered. When a CP is working in a faulty condition, it generates vibrations that can be measured using piezoelectric sensors. Collected data can be analyzed to extract time- and frequency-domain data. Interpreting the time-domain data showed that distinguishing the type of defect is not possible. However, indicators like kurtosis, skewness, mean, and variance can be used as input for the multi-layer perceptron (MLP) algorithm to classify pump faults. This study presents a detailed discussion of the vibration-based method outcomes, emphasizing the benefits and drawbacks of the multi-layer perceptron method. The results show that the suggested algorithm can identify the occurrence of different faults and quantify their severity during pump operation in real time. Full article

The water exit problem, which is ubiquitous in ocean engineering, is a significant research topics in the interaction between navigators and water. The study of the water exit problem can help to improve the structural design of marine ships and underwater weapons, allowing for better strength and movement status. However, the water exit problem involves complex processes such as three-phase gas–liquid–solid coupling, cavitation, water separation, liquid surface deformation, and fragmentation, making it challenging to study. Following work carried out by many researchers on this issue, we summarize recent developments from three aspects: theoretical research, numerical simulation, and experimental results. In theoretical research, the improved von Karman model and linearized water exit model are introduced. Several classical experimental devices, data acquisition means, and cavitation approaches are introduced in the context of experimental development. Three numerical simulation methods, namely, the BEM (Boundary Element Method), VOF (Volume of Fluid), and FVM (Finite Volume Method) with LES (Large Eddy Simulation) are presented, and the respective limitations and shortcomings of these three aspects are analyzed. Finally, an outlook on future research improvements and developments of the water exit problem is provided. Full article

In Tunisia, the date industry generates a large quantity of waste, raising environmental concerns. However, dates are rich in sugars, which offer a renewable source of nutrients for various applications. In this study, sugar extraction from two low-grade pitted date fruits (Alig and Kentichi) under ultrasound, was optimized using full factorial design. At 40 °C, for20 min, and with a liquid-to-solid ratio of 10 mL/g, the optimum sugar contents were 60.87% and 50.79% for the varieties Alig and Kentichi, respectively. The date extracts were chemically analyzed, revealing low fat and protein contents, but significant polyphenol and mineral contents in both varieties. HPLC-IR analysis revealed more inverted sugars (glucose and fructose) in the Alig variety and more sucrose in the Kentichi variety. FTIR and SEM analysis showed the efficiency of the ultrasonic treatment of the biomass in terms of improving mass transfer diffusion through ultrasonic cavitation. Thus, ultrasound-assisted extraction constitutes an effective method for the recovery of sugar from date waste. Full article

Floods pose significant challenges globally, particularly in coastal regions like the Philippines, which are vulnerable to typhoons and subsequent inundations. This study focuses on Naic city in Cavite, Philippines, using Geographic Information Systems (GIS) to develop flood risk maps employing two Multi-Criteria Decision-Making (MCDM) methods including Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). These maps integrate hazard, vulnerability, and exposure assessments to identify structures most vulnerable to flooding. Weight assignments in the study are derived from a literature review and expert opinions, reflecting the Philippines’ flood-prone geography and historical data. Structural attributes, categorized on a low to very high scale, were assessed based on field survey data from 555 buildings. AHP categorized 91.3% of buildings as moderate to very high risk, whereas TOPSIS placed 68% in this category, underscoring methodological disparities in data handling and assumptions. This research enhances understanding of flood threats and offers a decision-making framework for resilient flood risk management strategies. Identifying vulnerable buildings aims to support informed urban planning and disaster preparedness in flood-prone areas, thereby mitigating potential property, infrastructure, and livelihood damage. Full article

Background/Objectives: Focused ultrasound (FUS) and microbubble (MB) exposure is a promising technique for targeted drug delivery to the brain; however, refinement of protocols suitable for large-volume treatments in a clinical setting remains underexplored. Methods: Here, the impacts of various sonication parameters on blood–brain barrier (BBB) permeability enhancement and tissue damage were explored in rabbits using a clinical-prototype hemispherical phased array developed in-house, with real-time 3D MB cavitation imaging for exposure calibration. Initial experiments revealed that continuous manual agitation of MBs during infusion resulted in greater gadolinium (Gd) extravasation compared to gravity drip infusion. Subsequent experiments used low-dose MB infusion with continuous agitation and a low burst repetition frequency (0.2 Hz) to mimic conditions amenable to long-duration clinical treatments. Results: Key sonication parameters—target level (proportional to peak negative pressure), number of bursts, and burst length—significantly affected BBB permeability enhancement, with all parameters displaying a positive relationship with relative Gd contrast enhancement (p < 0.01). Even at high levels of BBB permeability enhancement, tissue damage was minimal, with low occurrences of hypointensities on T2*-weighted MRI. When accounting for relative Gd contrast enhancement, burst length had a significant impact on red blood cell extravasation detected in histological sections, with 1 ms bursts producing significantly greater levels compared to 10 ms bursts (p = 0.03), potentially due to the higher pressure levels required to generate equal levels of BBB permeability enhancement. Additionally, albumin and IgG extravasation correlated strongly with relative Gd contrast enhancement across sonication parameters, suggesting that protein extravasation can be predicted from non-invasive imaging. Conclusions: These findings contribute to the development of safer and more effective clinical protocols for FUS + MB exposure, potentially improving the efficacy of the approach. Full article

Climate change and the gradual phaseout of the spruce from Central Europe inspired us to study the effects of the ageing process of trees on wood properties. This study was conducted in old tree stands with significant involvement of the spruce (Picea abies (L.) H. Karst) in the ages between 122 and 177 years. The study material (samples) was collected from the selected trees to study wood properties such as density, resilience to compressive strength, resilience to bending strength, and modulus of elasticity. The results and findings of this study indicate that the spruce currently reaches the optimal technical quality of wood tissue at approximately 60 years of age. It is approximately 20 years earlier than the planned cutting age for the species. This could be due to water stress which led to adaptive changes in the wood tissue and earlier technical maturation of the wood in the studied trees. Significant radiant variabilities of wood properties of the Norway spruce were observed. It was determined that wood density does not fully reflect its mechanical properties, and it can be considered an indicator of the technical quality of wood tissue, but only within a limited scope. The results obtained may not only be applied in optimising the use of wood from spruce stands. They can also indicate the need to change the approach to managing spruce stands and their conversion towards broadleaf species. Full article

Both hydrodynamic cavitation (HC) and temperature elevation are important pretreatments for improving the performance of liquid food processing by reducing viscosity. In this study, we assessed the impact of HC and elevated temperature on the functionality of milk protein concentrate powder with 80% protein (MPC80) prepared from nanofiltration (NF) of ultrafiltration (UF) retentate. Skim milk was concentrated using UF, and the retentate was further subjected to HC and concentrated using NF, then spray dried to obtain MPC80 powder. The functionality of these powders processed using NF at 22 °C, NF at 50 °C, HC and NF at 22 °C, and HC and NF at 50 °C were evaluated. Rennet coagulation time of reconstituted MPC80 from different NF treatments was like skim milk when treated with 0.1% CaCl₂. High-temperature NF reduced the water solubility of MPC80 powder (70.03 to 79.20%) at room temperature, but it was similar when measured at 50 °C (86.05 to 92.91%). The HC improved foaming (92.22 to 112.89%) but did not impact the emulsifying capacity (59.58 to 61.38%) and heat stability (18.04 to 20.22 min). Results showed that the HC and high-temperature NF utilized to increase the production efficiency of MPC80 also maintained the functionality of the powders after spray drying. Full article

The increasing pollution of water bodies, due to the constant release of highly toxic and non-biodegradable organic pollutants, requires innovative solutions for environmental remediation and wastewater treatment. In this study, the effectiveness of different Advanced Oxidation Processes (AOPs) for the purification of water contaminated with Rhodamine B (RhB) dye at a concentration of 5 mg/L were investigated and compared. Using the classical ozonation strategy as a benchmark treatment, the research showed over 99% degradation of RhB within 4 min in a laboratory-scale batch setup with a capacity of 0.2 L. In contrast, a “chemical-free” process exploiting ultrasound (US) technology achieved a 72% degradation rate within 60 min. Further experiments were conducted using a pilot-scale rotor-stator hydrodynamic cavitation (HC) reactor on a 15 L solution leading to 33% of RhB removal in the presence of hydrogen peroxide (H₂O₂) at 75 mg/L. However, the use of an innovative cavitational reactor, which hybridizes HC with cold plasma, showed remarkable efficiency and achieved 97% degradation of RhB in just 5 min when treating a 5 L solution at an inlet pressure of 20 bar in a loop configuration. In addition, a degradation rate of 58% was observed in a flow-through configuration, emphasising the robustness and scalability of the HC/electrical discharge (ED) plasma technology. These results underline the potential of hybrid HC/ED plasma technology as an intensified and scalable process for the purification of water, as it offers a catalyst- and oxidant-free protocol. Full article

The aim of this study was to evaluate whether a system involving ozonated water and ultrasound causes de-epithelization of the human amniotic membrane (HAM). The experiment protocol was carried out in four stages. Stage I was carried out to determine the duration of the experiment. Stage II comprised the first experiment, involving four groups of samples studied in triplicate: control/natural (IN), processed with ultrasound in a liquid medium (US), processed with ozonated water (O3), and processed with ozonated water combined with ultrasound (US_O3). Stage III was performed to confirm the results, following the same steps present in Stage II. Stage IV involved the use of oxygen to confirm the hypothesis. Histological analysis was carried out to verify whether the effects of O₂ were similar to those of O₃. The system was activated, and ozonation was carried out for 10 min, as in the previous experiment, reaching a concentration level of 3.0 mg/L. The samples were submerged and positioned in the reservoir and processed separately for 55 min. The biochemical properties were assessed using Fourier transform infrared spectroscopy, and the morphology was examined using histology and scanning electron microscopy. The spectra of the samples exhibited similarities; however, subtle changes were highlighted, such as smooth band shifts and intensity changes. The morphology indicated that ultrasound achieved more efficient HAM de-epithelialization compared to ultrasound combined with ozonated water and ozonated water alone. One plausible hypothesis for this observation is that cavitation represents the primary mechanism responsible for de-epithelialization. When ultrasound is combined with ozone, the bubbles generated by ozone gas reduce the cavitation effect. This study is pioneering as it demonstrates an ultrasound system capable of the efficient de-epithelialization of the HAM. Full article

Several chemical analytical methods were applied to characterize the chemical structure of polysaccharides extracted from discarded apples and pomegranate peels using hydrodynamic cavitation methods in a circular economy perspective. In particular, the purity of the polysaccharides and the degrees of acetylation and methylation were evaluated by proton Nuclear Magnetic Resonance (¹H-NMR) analysis; simple sugars and galacturonic acid were analyzed simultaneously by High-Performance Anion Exchange Chromatography—Pulsed Amperometric Detector (HPAEC-PAD); the molecular weight of the extracted polysaccharides was determined by High-Performance Size Exclusion Chromatography-Refractive Index Detector (HPSEC-RID). The results showed a negligible presence of co-precipitated proteins/tannins, easily removed by dialysis, as well as other co-precipitated molecules such as monosaccharides and organic acids. Polysaccharides from apples consisted mainly of pectic material with a prevalence of homogalacturonans. Polysaccharides from pomegranate peels showed greater compositional variability with significant amounts of arabinose and galactose, a lower content of pectin, and the presence of rhamnogalacturonans I. Both polysaccharides were highly methylated and differed in the degree of acetylation, which could lead to different properties. Polysaccharides from apples presented two main molecular weights (>805 kDa and 348–805 kDa, respectively), while those from pomegranate peel showed a major fraction at 348 kDa and minor fractions < 23 kDa. In conclusion, the research tools proposed by this study have allowed defining the macrostructure of polysaccharides in a quick and efficient way to valorize these food by-products. Full article

The wastewater problem is becoming an increasingly significant environmental issue affecting various aspects of human activities. The generation of reactive oxygen species (ROS) in water through certain physicochemical processes, which can oxidise or degrade various organic and chemical compounds, offers an effective purification method. The main advantage of these methods is the elimination of chemical reagents. The aim of this work is to investigate the possibility of regulating the ROS content in water by altering the characteristics of the plasma discharge that occurs under hydrodynamic cavitation in the water flow. The ROS concentration was determined using the permanganate oxidation titration technique. It was found that the content of various reactive oxygen species in water after treatment can be controlled by varying the power of the electrical pulses applied. Additionally, this study obtained the dependence of the ROS concentration in treated water samples on storage time, with results indicating that sonoplasma treatment has a prolonged effect on the antibacterial properties of water. The analysis of water samples using a biological test culture of Salmonella typhimurium revealed the bacteriostatic properties of the water for at least 48 h after sonoplasma discharge treatment. Full article

Cavitation erosion, as a mechanical effect of destruction, constitutes a complex and critical problem that affects the safety and efficiency of the functioning of engineering components specific to many fields of work, the most well-known being propellers of ships and maritime and river vessels, seawater desalination systems, offshore oil and gas drilling platforms (including drilling and processing equipment), and the rotors and blades of hydraulic machines. The main objective of the research conducted in this paper is to experimentally investigate the phenomenology of this surface degradation process of maritime ships and offshore installations operating in marine and river waters. To reduce cavitation erosion of maritime structures made from Duplex stainless steels, the study used the deposition by welding of layers of metallic alloys with a high capacity for work hardening. The cavitation tests were conducted in accordance with the American Society for Testing and Materials standards. The response of the deposited metal under each coating condition, compared to the base metal, was investigated by calculating the erosion penetration rate (MDER) through mass loss measurements over the cavitation duration and studying the degraded zones using scanning electron microscopy (SEM), the energy-dispersive X-ray analysis, and hardness measurements. It was revealed that welding hardfacing with austenitic manganese alloy contributes to an approximately 8.5–10.5-fold increase in cavitation erosion resistance. The explanation is given by the increase in surface hardness of the coated area, with 2–3 layers of deposited alloy reaching values of 465–490 HV5, significantly exceeding those specific to the base metal, which range from 260–280 HV5. The obtained results highlighted the feasibility of forming hard coatings on Duplex stainless-steel substrates. Full article

Ultrasonic pretreatment is a crucial step in the bioconversion of lignocellulosic biomass, such as peapods, into valuable products. Ultrasonic pretreatment is a highly effective physical method that utilizes ultrasonic waves to enhance various processes. Biomass pretreatment is achieved through physical effects such as acoustic cavitation, which disrupts the biomass structure, and chemical effects like radical formation, which breaks down complex molecules. This article focuses on the characteristics, types, and applications of ultrasonic pretreatment in peapods, with a particular emphasis on its role in lignin removal and ultrasound design. An innovative mechanical design in a CAD application of a continuous ultrasound treatment with a capacity of 5 L and an FEA analysis of the equipment are presented as results, providing insights for the design and optimization of ultrasonic pretreatment processes. Full article

In this study, to further clarify the advantages of industrial applications of wire arc additive manufacturing (WAAM), the focus is on the repair of blades damaged by cavitation erosion using WAAM. A fan-type inducer was installed in a centrifugal pump experimental apparatus, and then paint erosion tests were conducted. Based on the tests, the fabrication time for repairing blades with a hybrid system of WAAM and machining was calculated and compared with that for fabricating a new part. It is concluded that applying WAAM to the fabrication process of an industrial turbopump has advantages not only in the manufacture of parts but also in the repair of such parts. Full article

Recent research has focused on the dynamic control and regulation of hydraulic devices like pumps and turbines to enhance the efficiency of water systems. These devices are adjusted to maintain nearly optimal hydraulic conditions and operating efficiency, although achieving both can be challenging due to factors like machine type and changes in distribution patterns. Incipient cavitation, which can cause mechanical damage and reduce efficiency, presents a specific challenge. It produces a distinct noise which this study aims to detect through a proposed methodology. Using the LES WALE model in OpenFOAM and Lighthill’s acoustic analogy, this research simulates and analyzes the noise generated by the dynamic of a confined flow. This work aims to be the starting point for more complex models. Full article