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Offshore piles are widely used as support and anchoring structures to provide stable support foundations. In this study, a novel torpedo pile is designed that combines water-jet technology and vibration loading to disturb/fluidize the cohesive sediments around the torpedo pile, reduce the resistance between the torpedo pile and cohesive sediments, and increase the efficiency of pile penetration and extraction. Experiments were conducted to investigate the characteristics of pile penetration and extraction in water-jet and vibration loading scenarios. The results indicated that the combined vibration and water jet method significantly reduced the resistance of the cohesive sediment to the torpedo pile during the pile penetration process, and the pile penetration speed increased as the water-jet pressure increased. The extraction efficiency of the torpedo pile was most significantly improved under the combined vibration and water jet method, and the maximum extraction force of the pile was reduced by approximately 78.2%. [ABSTRACT FROM AUTHOR]

Cutting is a pivotal step in the initial processing of fish products, encompassing beheading, trimming, slicing, and dicing. Traditional metal-knife cutting methods are marred by inefficiency, imprecision, and a propensity for bacterial growth, failing to meet market demands for precision and quality. Additionally, the reluctance of workers to perform manual labor in wet conditions exacerbates labor shortages and inefficiency. Adopting innovative cutting technologies, complemented by intelligent controls, is thus imperative. This study reviews the advancements and applications of waterjet and ultrasonic knives in sustainable cutting methods within the fish and food industries. It evaluates their respective merits and demerits, noting that waterjets excel in cutting hard-textured fish. At the same time, ultrasonic knives are adept at handling fish's viscous, elastic, and adhesive properties. The abstract further explores the integration of intelligent technologies in fish cutting, such as machine vision for precise cutting paths, simulation technology for adjusting process parameters, and multi-sensor data fusion for decision-making, which could potentially replace human labor. The study also addresses the current challenges and future directions for these technologies, highlighting the potential of artificial intelligence, machine learning, and deep learning to enhance the autonomy and robustness of fish-cutting equipment. By reducing operational and maintenance costs and integrating advanced technologies, the study envisions a future where fish cutting is more automated, intelligent, and capable of producing high-quality products efficiently to satisfy escalating market demands. This research is a valuable reference for industry professionals and researchers aiming to innovate in fish product processing, thereby enhancing the automation and intelligence of fish-cutting processes. [ABSTRACT FROM AUTHOR]

Biofouling release coatings (BRCs) have received attention for their potential to limit the negative impacts of biofouling on marine shipping. The calibrated water jet (CWJ, patent # US 8,984,958 B1) can be used to study the effectiveness of BRCs as a function of ship speed. Using a balance of force and linear momentum, we examined the theory and application of the CWJ for simulating the effect of ship speed on biofilm release for surfaces fouled under (1) laboratory and (2) natural conditions. Greater fouling release corresponded with an increase in CWJ pressure and, therefore, simulated ship speed for the surfaces coated with HullKote. The effectiveness of the CWJ was further confirmed for biofilm release from glass fouled naturally by submersion in flow-through seawater. A scaling analysis confirms that the results of these small-scale experiments are applicable to larger-scale biofouling release from ship hulls. This study is the first to utilize the pressure of a CWJ to quantify biofouling release as a function of simulated ship speed. [ABSTRACT FROM AUTHOR]

Copyright of Dicle University Journal of Engineering / Dicle Üniversitesi Mühendislik Dergisi is the property of Dicle Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ship-bridge collisions happen from time to time globally, and the consequences are often catastrophic. Therefore, this paper proposes a new high-pressure water jet interference (HPWJI) method for bridge pier protection against vessel collision. Unlike traditional methods that absorb energy by anti-collision devices to mitigate the impact force of ships on bridges, this method mainly changes the direction of ship movement by lateral high-pressure water jet impact, so that the ship deviates from the bridge piers and avoids collision. This paper takes China’s Shawan River as the background and simulates the navigation of a ship (weighing about 2000 t) in the HPWJI method in the ANSYS-FLUENT software. The simulation results show that the HPWJI method has a significant impact on the direction of the ship’s movement, enabling the ship to deviate from the pier, which is theoretically feasible for preventing bridge-ship collisions. The faster the ship’s speed, the smaller the lateral displacement and deflection angle of the ship during a certain displacement. When the ship speed is less than 7 m/s, the impact of water flow on the ship’s trajectory is more significant. Finally, this paper constructs a model formula for the relationship between the lateral displacement and speed, and surge displacement of the selected ship. This formula can be used to predict the minimum safe distance of the ship at different speeds. [ABSTRACT FROM AUTHOR]

Abstract Revealing the influence of confining pressure on the propagation and formation mechanism of rock cracks under particle impact is significant to deep rock excavation. In this study, the three-dimensional fracture reconstruction of the rock after particle impact was carried out by CT scanning, and the stress and crack field evolution of the rock under particle impact were analyzed by PFC2D discrete element numerical simulation. The results demonstrate that after particles impact, a fracture zone and intergranular main crack propagation zone are formed in the rock. The shear stress and tensile stress caused by compressive stress are the main reasons for the formation of the fracture zone, while the formation of the intergranular main crack propagation zone is mainly due to tangential derived tensile stress. The confining pressure induces prestress between rock particles such that the derived tensile stress needs to overcome the initial compressive stress between the particles to form tensile fractures. And the increase in the confining pressure leads to increases in the proportion of shear cracks and friction effects between rock particles, resulting in an increase in energy consumption for the same number of cracks. From a macroscopic perspective, the confining pressure can effectively inhibit the generation of cracks.

The large area overhanging of thick and hard roof is one of the critical reasons for inducing coal burst. Because of the shortcomings of deep borehole blasting and conventional hydraulic fracturing for the overhanging roof, the axial roof cutting technology of abrasive jet was developed. This technology achieves the best pressure relief by implementing prefabricated axial fractures and directional hydraulic fracturing in the roadway roof borehole to create an artificial fracture network in the roadway direction and tendency direction that is most conducive to roof collapse. The field application shows that the electromagnetic wave absorption ability of the stratum was enhanced, and the apparent resistivity was increased after the axial cutting roof technology of abrasive jet was implemented. During the mining operation of working face, the stress condition of the support was improved, and the release of micro-seismic energy was more stable, effectively reducing the risk of coal burst. On the basis of site observation, the mechanism of coal burst prevention by axial roof cutting of abrasive jet was revealed, that is, the plate-like structure fixed on both sides near the working face end is damaged by axial roof cutting, reducing the basic static load Ej, which is converted from the bending elastic energy of roof into the compression elastic energy of roadway surrounding rock, and reducing the strong additional dynamic load Ed, which is generated by the sudden fracture of roof, so that the roadway surrounding rock does not have the loading conditions for starting coal burst.

The article presents the research findings on the process of machining with a pulsating water jet. The study determined the influence of water velocity and pressure, providing insights into the dynamics of pulsating water jets. An evaluation of the generation process of pulsating water jets was conducted for various models of self-excited pulsating heads. The aim was to determine the impact of geometric parameters of the self-excited pulsating head and hydrodynamic working conditions on the performance of such a head, the dynamic characteristics of the water jet it produces, and its technological suitability for material erosion. In the first stage, simulation studies were carried out for three models of self-excited pulsating heads. Based on these studies, a solution with appropriate geometry was selected. Subsequently, experimental studies were conducted using the self-excited head and dedicated research setups. For the selected solution of the self-excited pulsating head, pulse durations, jet thrust forces, and frequency variations for different working pressure values were determined. The analysis showed a correlation between the geometric parameters of the head, pressure changes, and the characteristics of the generated pulses in the pulsed water jets. Pulse generation was made possible by increasing the water flow through side openings. Pulses with greater water volume exhibited increased erosive potential, particularly noticeable at higher pressures. It was found that pressure changes also affect the pulse frequency, with shorter intervals observed at lower pressures and longer intervals at higher pressures. The results presented in the paper highlight the importance of tool geometry and changes in water pressure at the inlet to the self-excited pulsating heads and the dynamics of the pulsed water jet. Research on the pulse generation mechanism and the assessment of erosive potential can form the basis for optimizing the design and operation of pulsating water jets in surface machining. This comprehensive understanding underpins the enhancement of efficiency and effectiveness of pulsating water jet applications in various industrial and manufacturing processes. [ABSTRACT FROM AUTHOR]

The substrate that adheres between the teeth of the traveling track plate during the operation of a deep-sea polymetallic nodule mining vehicle affects the driving performance, so this study aimed to investigate the effect of the water jet on the cleaning and decontamination performance of the track under different conditions. An optimization design method based on response surface methodology (RSM) is proposed. Based on the Box–Behnken design, the optimization variables of jet pressure, jet target distance, and impact angle, and the target response of jet strike pressure on tracks, were selected, and the numerical simulation method was combined with the response surface method to establish the regression model of the response of each optimization variable to the jet strike pressure on tracks and to determine the optimal parameter combinations. The study findings indicate that the primary factor influencing the pressure of the jet striking the crawler is the jet pressure. The hierarchical order of influence on the pressure of the jet striking the crawler, under the interaction of the three factors, is as follows: jet pressure and impact angle, jet pressure and target distance of the jet, and target distance of the jet and impact angle. The maximum pressure of the jet striking the crawler occurs when the jet pressure is 0.983 MPa, the target distance is 0.14 m, and the impact angle is 89.5°. Overall, the proposed design serves as a systematic framework for parameter optimization in the cleaning and decontamination process, and the research method and results provide theoretical references for the optimal design of mining truck desorption efficiency, which is critical for increasing mining efficiency and lowering energy consumption. [ABSTRACT FROM AUTHOR]

The water jet nozzle is a penetrating drilling tool, which sends the pumped water to the nozzle through a high-pressure hose. It can work in a variety of working environments. When it dredges the blockage in the pipeline, its structural parameters will affect the jet flow field in the pipeline. Taking the self-propelled water jet nozzle as the research object, SolidWorks was used to establish the nozzle model with different parameter structures. Based on Fluent, the k-ε turbulence model was used to simulate the jet of nozzles with different nozzle sizes and arrangements in the pipeline. The distribution of the jet flow field and the change in velocity and displacement of nozzles with different parameters in the pipeline were compared, and then computational fluid dynamics (CFD) were used to process the simulation data for further research. The results show that when the inclination angle of the rear nozzle is 35°, the attenuation of the front jet velocity and the fluctuation of the wall fluid velocity are the smallest. When the nozzle aperture is increased from 2 mm to 3.5 mm, the vortex area inside the pipe is reduced, and the velocity attenuation of the front jet is also reduced, with the velocity attenuation rate decreasing by about 10%. This study provides a reference for the design and parameter optimization of self-propelled water jet nozzles. [ABSTRACT FROM AUTHOR]

The Young's modulus and Poisson's ratio determined for the rocks under uniaxial or triaxial loading conditions represent necessary input parameters for solving many geotechnical tasks. However, these effective stiffness moduli, particularly the Poisson's ratios, measured on different samples sometimes substantially differ, even for visually compact and macroscopically homogeneous rock. This has been observed for Brenna sandstone, especially under conditions of conventional triaxial extensions. The aim of this study was, thus, to reveal differences in rock structure that could cause such behavior. Several complementary methods were used to investigate the structure of this sandstone: X-ray computed tomography (CT), visual analysis using optical scanning and stereo-microscopy, and a new method combining water jet erosion with these visualization techniques. Analyses of this structure revealed mechanically more resistant compact thick and adjacent thin weak layers. In rock samples, these layers have different patterns and orientations. To demonstrate the influence of layer orientation on effective stiffness moduli measured under different loading conditions, FEM calculations were performed for idealized structural models. The outcomes of this numerical analysis are in qualitative agreement with the results of the loading experiments and the layered structure revealed in the samples. The ability of the proposed method using water erosion to analyze the rock structure in detail was verified. The method offers an interesting alternative to standard visual and X-ray CT techniques. The numerical calculations indicate the importance of latent layered defects in sedimentary rocks for fine measurements of stiffness moduli (especially the Poisson's ratios) used as inputs for geotechnical applications. Highlights: Rock structure related to stratification has been analyzed by complementary methods. X-ray computed tomography revealed the irregular layered structure of the sandstone. A new method using water jet erosion of the rock surface confirmed the layers. Higher X-ray absorbance approximately corresponds to a higher mechanical resistance. A numerical model of the layers explains the differences in mechanical parameters. [ABSTRACT FROM AUTHOR]

Background: The implanted non-vascular stent is prone to fatigue fracture due to the periodic cyclic load caused by long-term physiological motion in the non-vascular lumen. Objective: To effectively study and predict the fatigue performance of non-vascular stents, an experimental setup was designed to simulate and conduct fatigue performance tests on non-vascular stents under various loads. This design simplified the periodic cyclic loads generated within non-vascular lumens, in accordance with the physiological motion patterns of non-vascular lumens, into pulsatile loads. Methods: To meet the requirements of different stents and various fluctuating load conditions during testing, the relationship between test conditions and the fatigue load of the stent was studied based on Fluent. Results: A fatigue test device with a special load module was built and used to complete the fatigue performance test of a group of esophageal stents. It can be found that the experimental device can satisfy the control and application of the fatigue load of the stent, and can effectively realize the testing requirements of the fatigue performance of the stent. Conclusion: In this paper, a non-vascular stent fatigue in vitro test device that can simulate the fluctuating load of a non-vascular lumen is designed. The results of flow field simulation, fatigue simulation, and actual fatigue test show that the device can meet the needs of fatigue test and has good versatility and operability. [ABSTRACT FROM AUTHOR]

Focused on the unsteady property of a cavitating water jet issuing from an orifice nozzle in a submerged condition, this paper presents a fundamental investigation of the periodicity of cloud shedding and the mechanism of cavitation cloud formation and release by combining the use of high-speed camera observation and flow simulation methods. The pattern of cavitation cloud shedding is evaluated by analyzing sequence images from a high-speed camera, and the mechanism of cloud formation and release is further examined by comparing the results of flow visualization and numerical simulation. It is revealed that one pair of ring-like clouds consisting of a leading cloud and a subsequent cloud is successively shed downstream, and this process is periodically repeated. The leading cloud is principally split by a shear vortex flow along the nozzle exit wall, and the subsequent cloud is detached by a re-entrant jet generated while a fully extended cavity breaks off. The subsequent cavitation cloud catches the leading one, and they coalesce over the range of x / d ≈ 1.8 ~ 2.5 . Cavitation clouds shed downstream from the nozzle at two dominant frequencies. The Strouhal number of the leading cavitation cloud shedding varies from 0.21 to 0.29, corresponding to the injection pressure. The mass flow rate coefficient fluctuates within the range of 0.59 ~ 0.66 at the same frequency as the leading cloud shedding under the effect of cavitation. [ABSTRACT FROM AUTHOR]

Objectives: Clinical trials testing new devices require prior training on dummies to minimize the "learning curve" for patients. Dentists were trained using a novel water jet device for mechanical cleaning of dental implants and with a novel cold plasma device for surface functionalisation during a simulated open flap peri-implantitis therapy. The hypothesis was that there would be a learning curve for both devices. Materials and methods: 11 dentists instrumented 44 implants in a dummy-fixed jaw model. The effect of the water jet treatment was assessed as stain removal and the effect of cold plasma treatment as surface wettability. Both results were analysed using photographs. To improve treatment skills, each dentist treated four implants and checked the results immediately after the treatment as feedback. Results: Water jet treatment significantly improved from the first to the second implant from 62.7% to 75.3% stain removal, with no further improvement up to the fourth implant. The wettability with cold plasma application reached immediately a high level at the first implant and was unchanged to the 4th implant (mean scores 2.7 out of 3). Conclusion: A moderate learning curve was found for handling of the water jet but none for handling of the cold plasma. Clinical relevance: Scientific rational for study: Two new devices were developed for peri-implantitis treatment (Dental water jet, cold plasma). Dentists were trained in the use of these devices prior to the trial to minimize learning effects. Principal findings: Experienced dentists learn the handling of the water jet very rapidly and for cold plasma they do not need much training. Practical implications: A clinical study is in process. When the planned clinical study will be finished, we will find out, if this dummy head exercise really minimised the learning curve for these devices. [ABSTRACT FROM AUTHOR]

Eruptions of volcanoes and geysers share many fundamental similarities: for example, they are manifestations of Earth’s geothermal energy, involving the pressure-driven expulsion of fluids from the Earth’s interior. However, while volcanoes can produce spectacular lava bubbles that burst, water bubbles are rarely observed on the surface of geysers. It is still unclear why some of these low-viscosity geyser systems produce none, while others produce them regularly. There is no quantification of the size, speed, and height of these bubbles at geysers, which is the gap we fill here. Strokkur creates a water bulge in its surface pool (bulge stage). When the bulge bursts, water is ejected into the air (jet stage). The steam then continues to rise buoyantly and drift away (drift stage). Here we study the evolution of the three stages using records from video camera campaigns and a local seismic network. We find that larger bulges are associated with larger ascent velocities and cause larger jet heights. As energy is channeled into a high jet, small seismic ground motions are recorded. The bulge formation itself is barely visible seismically. Our work suggests that the 0.74±0.27 s-long bulge stage can be used as a first-order proxy for predicting eruption height. This study might also be relevant for understanding fluid dynamics in volcanic systems.

Abstract Background Orthodontic treatment presents challenges with plaque accumulation around brackets, archwires, and elastics, leading to retained plaque and gingival inflammation. Conventional toothbrushing may not be enough, requiring additional oral hygiene aids like interproximal brushes, dental flosses, and water flossers. Limited research exists on comparing water flossing and interdental flossing in orthodontic patients. Therefore, this study aims to assess their effectiveness in maintaining oral hygiene during active orthodontic treatment. Methods A single-blind, randomized, parallel clinical study recruited orthodontic patients with full-mouth brackets and archwires. Thirty participants were randomly assigned to either water jet flossing or interdental flossing groups. All participants were instructed to brush twice daily with a provided toothbrush and toothpaste and use the assigned intervention once daily at night. Clinical measures, including the Gingival Bleeding Index (BI), Plaque Index (PI), and Gingival Index (GI), were recorded at baseline and day 14. Descriptive statistics and statistical tests were performed using SPSS software. Results The water jet flossing group demonstrated a slightly higher, albeit non-significant, benefit in plaque removal (median difference of 6.79%%, P = 0.279) and bleeding reduction (median difference of 5.21%%, P = 0.172) compared to the interdental flossing group after two weeks. Both groups showed significant reductions in gingival bleeding index and plaque index from baseline to the 2-week follow-up. The interdental flossing group had median mean percentage differences of 16.13%% (plaque index) and 23.57% (gingival bleeding index), while the water jet flossing group had median percentage differences of 21.87% (plaque index) and 32.29% (gingival bleeding index). No significant changes in gingival index grades were observed in either group. Conclusion Both water jet flossing and interdental flossing were effective in reducing plaque accumulation and gingival bleeding among orthodontic patients. While no significant differences were found between the two methods, water jet flossing showed a potential advantage. Further research is needed to validate its effectiveness, assess long-term impact, and understand its benefits for orthodontic patients.

Water jet technology, as a non-contact cutting and crushing technique, is commonly used in industries such as cleaning, rust removal, cutting, drilling, and mining. It enables a green and environmentally friendly production process by avoiding environmental pollution, heat generation, blade replacement, and sharpening issues. Cutting, cleaning, and crushing techniques are widely applied in various stages of agricultural production, but mostly through contact-based methods. The application of non-contact water jet technology in the agricultural field is still in its infancy. This paper summarized the current application status and research progress of water jet technology in different operational stages of agriculture, including sowing, management, field harvesting, and post-harvest processing. The specific requirements of key parameters for different operational objects and stages were analyzed. Furthermore, the challenges of the application of water jet technology in agriculture were discussed and the research development tendency was prospected. The review intended to provide references for the promotion and green sustainable development of water jet technology in the agricultural field. [ABSTRACT FROM AUTHOR]

Underground pipe defects or cracks under transport infrastructure can cause water leakage to upper soil layers (e.g. subgrade and capping), inducing local cavities or even failure of overlying road/railway formation. Although numerous studies on the instability of granular beds induced by injected water have been conducted, most of them focused on the behaviour of saturated granular beds, while research on dry granular beds is still limited. This paper aims to address this gap using a numerical model coupling volume of fluid method with discrete element method. We observed that dry granular beds go through three distinct regimes as water jet velocity increases including stationary, stable deformation with heave and fluidisation. However, the flow velocities required to deform and fluidise dry granular beds are significantly higher than those required for saturated beds. Increasing granular bed thickness can alter its failure mechanism from full depth to localised erosion, leading to cavity formation around pipe cracks prior to the bed fluidisation. The gravitational and frictional components of granular mass are identified as two main resisting forces of dry granular beds against water jet force, evidenced by the increase of critical jet velocities as particle density and friction coefficient increase. Nevertheless, the moblised zone of granular mass is practically independent of both the buried depth of dry granular beds. [ABSTRACT FROM AUTHOR]

Objective: There are several methods of treating hard-to-heal (chronic) wounds, each differing in terms of efficiency, selectivity, speed, cost and pain. The objective is to activate a wound to initiate the healing cascade. For this pilot study we assessed the feasibility of a new microjet wound therapy technology compared to standard sharp debridement in wound outcomes. Method: A randomised, controlled, open-label pilot study was conducted in one outpatient wound clinic in Western Switzerland from March 2022 to May 2023. Results: A total of 13 consecutive patients were randomly assigned to receive either microjet wound therapy (n=5) or standard mechanical debridement with instruments (n=8). As a feasibility study, there was insufficient power to detect significant differences between the groups. However, in the intervention group, our analysis may indicate a modestly faster reduction in wound area. Microjet wound therapy appears to alleviate patient anxiety and offer cost savings due to the potential for reduced time, as well as the number of required treatments. This meant fewer overall consultations. Conclusion: This study highlights a trend that may indicate that microjet therapy holds value in promoting faster healing of hard-to-heal wounds, and it provides a feasibility basis for a sufficiently powered multicentre trial. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effect of different oral irrigators on the sub‐gingival microbiome composition in patients with naturally occurring plaque‐induced gingivitis. Materials and Methods: Sub‐gingival plaque was collected from adults participating in a clinical trial assessing the efficacy of oral hygiene with two different oral irrigators (Waterpik Water Flosser [Group 1] and Oral‐B Water Flosser [Group 2]) versus dental flossing (Group 3) for microbiome analysis. Plaque samples were reflective of naturally occurring plaque‐induced gingivitis at baseline and of gingival health at the endpoint (4 weeks). Clinical measures of gingival inflammation were collected, and the sub‐gingival microbiome was analysed by 16S rRNA sequencing to identify amplicon sequence variants. Results: Oral hygiene instruction with self‐performed manual toothbrushing and water‐jet irrigation led to significant reductions in inflammation for all groups; both oral irrigators outperformed flossing in bleeding‐on‐probing reduction (p <.001). Microbiome diversity of sub‐gingival plaque remained relatively stable over time, but significant changes were noted in certain taxa, consistent with increases in the relative abundance of commensals and reductions in late colonizers and periodontal pathogens in the water‐jet groups. Conclusions: Reduction in gingival inflammation at 4 weeks within the water‐jet groups is accompanied by slight but critical changes in microbiome composition. Although biodiversity does not substantially change within 4 weeks during the resolution of naturally induced gingivitis, significant relative increases in commensal early colonizers such as Streptococcus, Veillonella and Fusobacterium were accompanied by a shift towards a less anaerobic microbiota associated with return to health. These changes were contingent upon the type of interdental hygiene, with Group 1 exhibiting more significant alterations in microbiome composition towards a periodontal‐health‐compatible community. [ABSTRACT FROM AUTHOR]

The purpose of aeration in water is to transfer or remove gases from the water. Dissolved oxygen is critical for living life. In water engineering, aeration and oxygen transfer using water jets are common. In this study, various venturi nozzles with air holes in the throat portion were manufactured and meaningful experiments were conducted to determine their oxygen transfer efficiency and aeration performance., the venturi nozzles with throat diameters 14, 17 and 20 mm were used in the experimental study. The ratio of the diameter of the air holes to the diameter of the throat portion is taken as 0.1, 0.2 and 0.3. Different experiments were carried out for nine different hole diameters. In addition, the ratio of the throat portion length to the throat portion diameter was taken as 1.00 and 0.50. For all nozzles, the ratio of outlet length to outlet diameter was taken as 1 and 2. In addition, comprehensive experiments were carried out for a venturi, considering the ratio of outlet length to outlet diameter as 1, 2, 3, 4 and 5. The experiments were also conducted for the circular nozzle to make comparisons. In this study, venturi nozzles gave better results than circular nozzles, and higher aeration performance values were obtained for the ratios 0.2 and 0.3, 1, 0.50 and 0.50. It was found that the aeration performance of the venturi nozzle was approximately 6.5 times higher than the air entrainment rate performance of the circular nozzle and 2.5 times higher in terms of oxygen transfer. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to investigate the improvement of the rock breaking ability of a disc cutter under hard rock conditions, the use of a water jet-assisted cutter to break rock was explored as a promising new rock breaking technology. The impact of slit spacing on the effectiveness of slit-assisted cutter rock breaking was verified through rock breaking tests in this study. It was demonstrated that, under specific conditions of rock material, penetration depth, and slit depth, there exists a threshold spacing for slit-assisted cutter rock breaking. Only when the slit spacing is less than the threshold spacing, can penetration crushing occur on the slit side. Additionally, the rock shear damage theory was applied to analyze and propose a linearized threshold spacing prediction model, which indicates that the threshold spacing is linearly correlated with the difference between the slit depth (L) and the penetration depth (H), denoted as (L -H). [ABSTRACT FROM AUTHOR]

Using the method combining experiments and numerical simulations, the dynamic behavior of explosion bubbles for the cylindrical charges with different length-diameter ratios (L/D) under fixed square plates was studied. Explosion tests of TNT explosives with the mass of 2.5g and L/D of 1:1 and 2:1 under a fixed square plate was carried out, and the evolution of explosive bubbles was recorded by the high-speed camera. ABAQUS software was used to numerically simulate the underwater explosion bubble evolution process of cylindrical charges with L/D of 5:1, 10:1, and 20:1 under vertical and horizontal settings. The results show that there is no obvious difference between the explosion of 2.5g TNT explosives with a L/D of 1:1 and 2:1 under the board. When the explosives are placed vertically, the difference in the initial shape of the explosion bubble caused by different L/D of the explosives will be quickly eliminated during the evolution of the bubble. Moreover, the L/D and the starting position have effects on the water jet. When the explosives are placed horizontally, the symmetry of the bubble and the shape of the water jet will be affected by the location of the initiation point. To be specific, for the detonation from the end face, there is a slight asymmetry in the process of the bubble expansion, and the jet is offset in the direction of the starting point. Moreover, the larger the L/D of the explosives, the wider the water jet in the explosion bubble, and the smaller the load of the water jet. For the detonation from the center, the explosive bubble forms a vertical water jet without offset. [ABSTRACT FROM AUTHOR]

Pork is the second most consumed meat in the world. The scale and intensification of pig farming have been everincreasing in recent years. It is required for the continuous development of Precision Livestock Farming technologies. Cleaning inside the house is one of the most important parts of precision pig farming. Among them, the water jet cleaning pig manure is assumed as a two-phase flow of water-pig manure particles. This study aims to investigate the process and effect of water jet cleaning pig manure. Numerical simulations were conducted to simulate the two-phase interaction between the water jet and pig manure using computational fluid dynamics (CFD) and discrete element method (DEM). Firstly, the water jet flow field model was established to complete the flow net independence verification for the grid partitioning using Fluent software. Then, the pig manure particle model was constructed using Rocky. The relative error between the simulation and the actual measurement was 1.78%, indicating the reliability of the pig manure physical properties parameters and the pig manure simulation model. A linear adhesion model was introduced to optimize the pig manure model using coarse-grained modeling. The total number of particles was also reduced for the less computational complexity during simulation. Finally, fluid-solid coupling experiments were conducted using Fluent-Rocky DEM. The experiments were carried out to simulate the vertical impact cleaning of a pig manure layer at a distance of 300mm from the nozzle outlet using a water jet. The results showed that: 1) The process of water jet cleaning pig manure was divided into three stages: free jet cleaning, submerged jet cleaning, and impact strengthening. The water jet flew from the nozzle inlet and stabilized on the surface of the pig manure layer after approximately 0.3 s. As the cleaning time increased, the pig manure layer showed bowl-shaped pits with a central peak forming at the center of the pit. 2) The highest cleaning efficiency occurred within 0.45 s after the continuous water jet reached the surface of the pig manure layer. A conical nozzle performed better cleaning depth and cleaning efficiency than a straight one under the same structural parameters and operating pressure. The cleaning amount of the conical nozzle increased by about 0.83% at a continuous cleaning time of 0.45 s, compared with the straight one. 3) The maximum horizontal velocity of the conical nozzle was obtained at the target cleaning depths of 10 and 30mm. The maximum cleaning speed was negatively correlated with the cleaning target depth and working pressure, whereas, there was no significant relationship with the nozzle outlet diameter. There was the greatest impact on the depth of the cleaning target. The larger the nozzle outlet diameter and working pressure were, the larger the cleaning width and the larger the cleaning area were within the same time. A coarsegrained model was used to simulate the granulation of pig manure particles. A summary was made on the correlation between the CGM values and the mechanical parameters of pig manure particles. The efficiency of CFD-DEM coupled simulation was improved for the water jet cleaning of pig manure. The effectiveness of the simulation was verified to test the cleaning effect of the nozzle using the cleaning test platform. The research results can provide valuable information and theoretical references for the design and optimization of cleaning equipment for livestock and poultry manure. [ABSTRACT FROM AUTHOR]

To establish whether the use of a WaterPik® alongside a manual toothbrush (WaterPik® + MTB) is more effective for maintaining oral hygiene compared to the use of a manual toothbrush alone (MTB) in patients wearing fixed orthodontic appliances. A single-centre, two-arm, parallel-group, single-blind, randomised controlled clinical trial with a 1:1 allocation ratio. Orthodontic department at York Hospital, York Teaching Hospitals NHS Foundation Trust, UK. A total of 40 fit and well participants, aged 10–20 years, being treated with upper and lower fixed orthodontic appliances. Participants were randomly allocated, using stratified block randomisation, to the control group (MTB) or intervention group '(Waterpik® + MTB)'. Plaque, gingival and interdental bleeding indices were recorded at baseline, 8 weeks, 32 weeks and 56 weeks. A generalised linear mixed model was used to assess differences between groups. An interim analysis of results was performed with 40 patients recruited and 85% of data collected. The overall mean differences between the groups were as follows: plaque index = 0.199 (P = 0.88, 95% confidence interval [CI] −0.24 to 0.27); gingival index = −0.008 (P = 0.94, 95% CI −0.22 to 0.20); and interdental bleeding index = 5.60 (P = 0.563, 95% CI −13.22 to 24.42). No statistical difference between the two groups was found for any variable. The trial was stopped at this point. In terms of oral hygiene, our study did not find evidence to support the claim of benefit of using a Waterpik® in addition to a manual toothbrush for patients wearing fixed orthodontic appliances. [ABSTRACT FROM AUTHOR]

Preventing plunge pool scouring in hydraulic structures is crucial in hydraulic engineering. Although many studies have been conducted experimentally to determine relationship between the scour depth and water jets in several fields, available equations have deficiencies in calculating the exact scour due to complexity of scour process. This study investigated local scour depth in plunge pool using Metaheuristic Artificial Bee Colony-Optimized Feed Forward Neural Network (ABCFFNN), variational mode decomposition (VMD) and ensemble empirical mode decomposition (EEMD) techniques. To set modeling, the input parameters are impact angle, densimetric Froude number, impingement length, and nozzle diameter. The models' training and testing were conducted using data available in the literature. The models' performances were compared with experiments. The results demonstrate that scour depth, length, width, and ridge height can be calculated more accurately than available equations. A rank analysis was also applied to obtain the most critical parameter in predicting scour parameters in water jet scouring. ABC-FFNN, VMD-ABCFFNN and EEMD-VMD-FFNN hybrid models were performed to obtain scour parameters. As a result, ABC-FFNN algorithms produced the best solution to predict the scour due to circular water jets, with the values for training (R2: 0.331 to 0.778) and testing (R2: 0.495 to 0.863). HIGHLIGHTS This study analyzed the scour due to water jets using metaheuristic algorithms based on artificial bee colony ABC.; Metaheuristics optimized feed forward neural network (ABC-FFNN) and pre-processing techniques were used to predict the scour characteristics.;

The water jet nozzle is a penetrating drilling tool, which sends the pumped water to the nozzle through a high-pressure hose. It can work in a variety of working environments. When it dredges the blockage in the pipeline, its structural parameters will affect the jet flow field in the pipeline. Taking the self-propelled water jet nozzle as the research object, SolidWorks was used to establish the nozzle model with different parameter structures. Based on Fluent, the k-ε turbulence model was used to simulate the jet of nozzles with different nozzle sizes and arrangements in the pipeline. The distribution of the jet flow field and the change in velocity and displacement of nozzles with different parameters in the pipeline were compared, and then computational fluid dynamics (CFD) were used to process the simulation data for further research. The results show that when the inclination angle of the rear nozzle is 35°, the attenuation of the front jet velocity and the fluctuation of the wall fluid velocity are the smallest. When the nozzle aperture is increased from 2 mm to 3.5 mm, the vortex area inside the pipe is reduced, and the velocity attenuation of the front jet is also reduced, with the velocity attenuation rate decreasing by about 10%. This study provides a reference for the design and parameter optimization of self-propelled water jet nozzles.

The substrate that adheres between the teeth of the traveling track plate during the operation of a deep-sea polymetallic nodule mining vehicle affects the driving performance, so this study aimed to investigate the effect of the water jet on the cleaning and decontamination performance of the track under different conditions. An optimization design method based on response surface methodology (RSM) is proposed. Based on the Box–Behnken design, the optimization variables of jet pressure, jet target distance, and impact angle, and the target response of jet strike pressure on tracks, were selected, and the numerical simulation method was combined with the response surface method to establish the regression model of the response of each optimization variable to the jet strike pressure on tracks and to determine the optimal parameter combinations. The study findings indicate that the primary factor influencing the pressure of the jet striking the crawler is the jet pressure. The hierarchical order of influence on the pressure of the jet striking the crawler, under the interaction of the three factors, is as follows: jet pressure and impact angle, jet pressure and target distance of the jet, and target distance of the jet and impact angle. The maximum pressure of the jet striking the crawler occurs when the jet pressure is 0.983 MPa, the target distance is 0.14 m, and the impact angle is 89.5°. Overall, the proposed design serves as a systematic framework for parameter optimization in the cleaning and decontamination process, and the research method and results provide theoretical references for the optimal design of mining truck desorption efficiency, which is critical for increasing mining efficiency and lowering energy consumption.

Focused on the unsteady property of a cavitating water jet issuing from an orifice nozzle in a submerged condition, this paper presents a fundamental investigation of the periodicity of cloud shedding and the mechanism of cavitation cloud formation and release by combining the use of high-speed camera observation and flow simulation methods. The pattern of cavitation cloud shedding is evaluated by analyzing sequence images from a high-speed camera, and the mechanism of cloud formation and release is further examined by comparing the results of flow visualization and numerical simulation. It is revealed that one pair of ring-like clouds consisting of a leading cloud and a subsequent cloud is successively shed downstream, and this process is periodically repeated. The leading cloud is principally split by a shear vortex flow along the nozzle exit wall, and the subsequent cloud is detached by a re-entrant jet generated while a fully extended cavity breaks off. The subsequent cavitation cloud catches the leading one, and they coalesce over the range of x/d≈1.8~2.5. Cavitation clouds shed downstream from the nozzle at two dominant frequencies. The Strouhal number of the leading cavitation cloud shedding varies from 0.21 to 0.29, corresponding to the injection pressure. The mass flow rate coefficient fluctuates within the range of 0.59~0.66 at the same frequency as the leading cloud shedding under the effect of cavitation.

In a fire outbreak, firefighters are expected to rapidly extinguish fires to stop the spread of damage and prevent secondary disasters. We proposed the concept of a dragon firefighter (DFF), which is a flying-hose-type firefighting robot. We developed a 3.6 m long DFF equipped with two nozzle units and achieved stable flight. However, the system was not yet completed because the root of the robot, which should have been operated remotely, was operated manually. In addition, the system’s reliability was insufficient to successfully repeat the demonstration several times. The development of a robot demonstration system is crucial for the practical application of such a firefighting robot. In this study, we developed a demonstration system for a remotely controllable 4 m flying firehose robot for demonstration at the World Robot Summit 2020 (WRS 2020) opening ceremony in Fukushima as a milestone. This paper focuses on the following issues: 1): installation of the remotely controllable mobile base, 2): redesign of the water channels (the sizes of nozzle outlets) to get enough thrusts to fly with a fire engine, 3): development of nozzle units with a larger movable range (1.5 times larger than the conventional nozzle) in addition to waterproofing technique to improve system reliability, and 4): redesign of a passive damping mechanism to ensure better stability. Thus, a firefighting demonstration was successfully conducted at the opening ceremony of the World Robot Summit 2020 in Fukushima, Japan, and we discuss the lessons learned through the demonstration. We found that the developed DFF system incorporating a mobile base could achieve remote fire extinguishing.

In order to understand the transmission mode of laser in water jet–guided laser (WJGL) after entering blind holes, the flow characteristics of water jet in blind holes and the formation process of WJGL processing blind holes were studied. Firstly, the flow characteristics of water jets in blind holes under different water jet and blind hole conditions were studied through numerical simulation, including water jet diameter d (0–300 μm), hole diameter D (0–300 μm), and water jet velocity v (0–200 m/s). Secondly, single-point drilling experiments with different processing times (2–40 s) were conducted using WJGL technology to characterize the formation process of blind holes. Finally, the transmission mode of laser in blind holes and formation process mechanism of blind hole processed by WJGL were analyzed. The simulation results indicate that the process of water jet entering the blind hole can be divided into incident stage, rebound stage, and stable stage. The transmission of water jet in blind holes is influenced by D/d and v. When D/d is greater than 2.3, the water jet can stably transmit to the bottom of the blind hole. Taking 75 m/s and 150 m/s as the change points, as v increases, the stable transmission length of the water jet first decreases, then remains unchanged, and then increases. The experimental results indicate that with the increase of processing time, the formation process of blind holes undergoes rapid drilling stage, uniform reaming stage, bottom reaming stage, and stable stage. Under experimental conditions, the depth of blind holes first increases and then stabilizes with increasing processing time. The maximum depth of blind holes processed by WJGL is 720 μm. This article reveals the flow pattern of micro water jets in blind holes and the factors that affect their stable transmission for the first time. From the perspective of the guiding effect of water jets on laser, it is revealed that laser propagates along a straight line in a blind hole. The simulation and experimental results have guiding significance for improving the application of WJGL technology in blind hole processing. [ABSTRACT FROM AUTHOR]

Water jet is an extensively used method for materials processing due to the possibility of operating in different environments (air, water), its safety during working with hazardous materials, and efficiency while cutting hard and brittle rock blocks. In this article, we have presented results of the research on processing aerated concrete by means of pulsating water jest. The discontinuity in water flow through the nozzle was achieved using an own-construction self-excited head. The intermittent flow had the greatest effect during operating in water environment. Machining efficiency for continuous and pulsating water jest was indicated by measuring erosive effects on processed materials. The occurrences of pulsations were confirmed while measurement of water jet thrust forces acting on piezoelectric sensor. It was concluded that pulsating water jet had greater processing effectiveness in a certain circumstances compared to the continuous flow, during the surface processing of concrete blocks. [ABSTRACT FROM AUTHOR]

Based on the experimental study of cavitation water jet impact on microforming, a single round hole micro-die was used in this paper. The effect of different process parameters on the performance of 304 stainless steel foil was examined, which involves the nanometer hardness, and elastic modulus. The nano-indentation tester was used to test the nano-hardness of the formed part, and the performance of the workpiece before and after the impact was analyzed. The nano hardness and elastic modulus increased significantly with an increase in the incident pressure. When the incident pressure was 20 MPa and the impact time of 5 min, the hardness increased by at least 122%, and the elastic modulus increased by at least 76%. After the cavitation water jet shocked the metallic foil of the SEM analysis and the results indicated that, as the incident pressure increases, the surface morphology of the formed part changes from approximately spherical to spherical, and the spherical roundness increases. In addition, there were different degrees of defects at the bottom of the formed part, and as the incident pressure increased, the bottom defects became more and more obvious, from micro-cracks to micro-layer cracks.

In order to improve the efficiency of fish cutting and processing, the qualified rate of products, and reduce the labor cost, this paper explored a kind of mackerel fillets water jet cutting technology. With frozen mackerel fillet as raw material, the second- class spacing was performed by water knife cutting after thawing. The cutting rate, fish loss rate and sensory value of the cutting surface were used as evaluation indexes, and the thickness, water knife pressure and water knife action time were used as process parameters. The multi-index comprehensive scoring method was used to evaluate the cutting effect of mackerel mackerel fillets. The water jet cutting technology of mackerel fillet was optimized by single factor and orthogonal tests. The results showed that with the increase of fish fillet thickness, the cutting rate and sensory value of the cutting surface decreased, and the loss of fish meat decreased first and then increased; With the increase of water jet pressure and water jet action time, the cutting rate increases, the fish loss rate decreased, and the sensory value of the cutting surface first increased and then decreased. The optimum water jet cutting technology for mackerel fillet was as follows: fillet thickness was 13 mm, water knife pressure was 50 MPa, and water knife action time was 2.0 s. Under these conditions, the cutting rate of mackerel fillet was 99. 8%, the fish loss rate was 0.133 %, the sensory value of the cutting surface was 8.5 points, and the overall cutting effect score was 99.5 points. [ABSTRACT FROM AUTHOR]

Introduction. The study aims to enhance the hydro-cutting process by modifying the working fluid using water, water-ice and water-nitrogen jets when cutting deep-frozen food products. Materials and methods. Materials: Hake fish fillets, beef meat, and ice samples at -30 °C as a model sample of meat at - 25 °C. Experimental Methods: Hydro-cutting unit is utilized to cut food products with a water jet. The experiments were conducted at food temperatures ranging from -3 to -25 °C, with pressure variations from 50 MPa to 500 MPa, nozzle diameters of 0.2·10-3 to 0.8·10-3 m and the speed of movement of the jet of the working liquid relative to the sample of the food product of 0.01 to 0.07 m/s. Results and discussions. It was found that the increasing the pressure from 200 to 500 MPa results in a nearly 21-fold and 6- fold increase in the depth of cut for nozzles with diameters of 0.2x10-3 and 0.4x10-3 m, respectively. Additionally, increasing the nozzle opening diameter leads to an increase in the depth of cut in the frozen food product. At the same time, the maximum cutting depth in the food product at the temperature of -11 °C did not exceed 82,5x10-3 m with the pressure of 500 MPa. Reducing the temperature of the food product to -11 °C and below excludes the possibility of using water jet cutting at the pressure of 250-300 MPa, and the necessity of creating pressures above 300 MPa causes a sharp increase in the cost of water jet cutting equipment. Experimental verification was conducted to evaluate the feasibility of using a water jet with small ice particles to enhance the hydro-cutting. The process of hydro-cutting deep-frozen food products can be intensified by adding small ice particles to the water jet, which is highly effective but also expensive. Alternatively, a water-nitrogen jet that employs ice microparticles as an abrasive, formed by cooling the water jet with liquid nitrogen vapour, is a costeffective way to significantly improve the water jet cutting process for deep-frozen food products. Conclusions. To significantly intensify the hydro-cutting process of deep-frozen food products, it is most expedient to use a water-nitrogen jet as the working fluid, in which ice microparticles are formed in the process of cooling a water jet with vapours of liquid nitrogen. [ABSTRACT FROM AUTHOR]

Currently, water jets are mainly used in the fields of mechanical processing and mining collection. This paper creatively introduces them to the field of safety assurance for inland navigation. Compared with the traditional bridge anti-striking methods such as intelligent early warning and passive anti-striking, this method can form an "interference zone" by changing the water flow conditions in the local bridge water areas, causing the yawing moment of the yaw ship to change, thereby causing the ship's course to change, and thus guiding the ship to move away from the bridge pier to realize active anti-striking of the ship. In this paper, a combination of generalized model testing and numerical simulation was used to study the effects of different nozzle pressures and different ship pier distances of the water-jet generator on the trajectory and drift angle of the stalled ship. The results showed that the numerical simulation was in good agreement with the model test results. Within the interference zone, the distance between the ship and the pier increased rapidly after the action of the disturbance zone to 9.1, 5.8, and 6.2 times the ship's width, respectively, reaching a safe distance. During the process of being affected by the interference zone, the maximum drift angle of the yaw ship was less than 20°, the course of the ship was generally stable, and the drift angle comparison error was a maximum of 10.6%, a minimum of 3.5%, and an average error of 6.7%. A negative peak and a positive peak of four times the absolute value of the negative peak occurred in the yaw-moment ephemeral curve during the ship's passage through the interference area. The method had a notable effect on the anti-striking of stalled ships and two invention patents applied for in the course of research. [ABSTRACT FROM AUTHOR]

Aiming at the low rock-breaking efficiency of TBM disc cutters in tough rock environments, A new experimental machine combined with the high-pressure water jet rock-breaking method was designed. It can flexibly change the cutting parameters of the water jet, such as spray position, spray height, pressure, etc. Moreover, the three-direction load of the disc cutter during the rock-breaking process can be obtained accurately by strain testing. The rock-breaking experiment reached the following conclusions. The experimental machine can meet the design function. In this study, the normal and rolling forces when the disc cutter breaks rock are significantly lower than the traditional, 26.90% and 28.39%, respectively. The lateral force increased slightly, about 31.17%. Although the energy consumption of water-jet-assisted is higher than the traditional rock-breaking method, the volume of broken rock per unit of time is approximately 5.85 times that of the traditional. It is feasible to increase the energy cost to increase the excavation speed. On the rock surface after the water jet experiment, a rock ridge appears on the rolling trajectory of the disc cutter, which is not conducive to further breaking the rock. The cutting depth of the water jet needs to be adjusted to reduce the height of the rock ridge. [ABSTRACT FROM AUTHOR]