Search Results (40)

Background and Aims: Gastroesophageal reflux disease (GERD) is the most common esophageal disorder worldwide and a progressive condition leading to Barrett’s esophagus and adenocarcinoma. Continuous medical therapy with proton pump inhibitors fails to restore the antireflux barrier and is unable to relieve symptoms in up to 40% of patients. A tailored and standardized antireflux surgical procedure may increase cure rates and meet patient expectations. Methods and Results: Antireflux surgery aims to reestablish the natural antireflux barrier, which includes the diaphragmatic crura, the lower esophageal sphincter (LES), and the angle of His along with the gastroesophageal flap valve. For decades, the Nissen total fundoplication has been the primary procedure and remains the gold standard for surgical treatment. Alternatives such as Toupet partial fundoplication, Dor partial fundoplication, and the magnetic sphincter augmentation (LINX™) procedure have been developed to mitigate side effects like dysphagia, gas-bloat syndrome, and the inability to belch or vomit. Recent clinical findings regarding a novel procedure, RefluxStop™, indicate that restoring the gastroesophageal flap valve, in conjunction with anterior fundoplication and a silicone device for stabilizing the LES beneath the diaphragm, can achieve lasting reflux control and enhance patient-reported outcomes. Conclusions: The planning of healthcare services and actionable strategies to improve equity and quality of treatment is critical to address the global burden of GERD. Modern laparoscopic surgery for GERD is safe and effective and should be performed in centers offering a complete diagnostic pathway and specific surgical techniques tailored to the individual GERD phenotype. Shared decision-making between the surgeon and the patient is essential for the choice of operation. A personalized approach can offer clinical benefits over total fundoplication and improve patient-reported outcomes. Full article

Diaphragm valves play a crucial role in controlling fluid flow in piping systems, and their hydraulic performance directly impacts system efficiency. This study employs numerical simulations using OpenFOAM v8 to investigate the hydraulic characteristics of a diaphragm valve, focusing on the effects of inlet boundary conditions and turbulence models on head loss. At the maximum valve opening, two inlet conditions of OpenFOAM, flowRateInletVelocity and timeVaryingMappedFixedValue, were compared. Results show that the flowRateInletVelocity inlet condition yields simulation results in excellent agreement with experimental data, validating its reliability. Five turbulence models (Standard k-ε, Realizable k-ε, RNG k-ε, SST k-ω, and Spalart-Allmaras) were evaluated, revealing that the SST k-ω model offers the highest computational accuracy in capturing flow field details and head loss, while the Spalart-Allmaras model demonstrates significant discrepancies. Further analysis under varying valve openings and flow rates identifies an exponential relationship between head loss and value opening, with the most pronounced changes occurring below 50% opening. These findings provide a theoretical basis for optimizing diaphragm valve designs and enhancing the accuracy of CFD simulations in hydraulic engineering applications. Full article

The diaphragm is the primary muscle involved in the ventilatory pump, making it a vital component in mechanical ventilation. Various factors in patients who require mechanical ventilation can lead to the deterioration of the diaphragm, which is associated with increased mortality. This deterioration can arise from either excessive or insufficient support due to improper adjustment of ventilation programming variables. It is essential for healthcare professionals to make appropriate adjustments to these variables to prevent myotrauma, which negatively impacts muscle structure and function. One recognized cause of muscle injury is eccentric work of the diaphragm, which occurs when muscle contractions continue after the expiratory valve has opened. Current evidence suggests that these eccentric contractions during mechanical ventilation can be harmful. This brief review highlights and analyzes the existing evidence and offers our clinical perspective on the importance of properly adjusting ventilation programming variables, as well as the potential negative effects of eccentric diaphragm contractions in routine clinical practice. Full article

To improve the practicability of electro-mechanical converters in hydraulic systems, especially in control valves, a hydraulic force/displacement amplification mechanism was addressed. The amplification mechanism includes a rolling diaphragm (RD) and a corrugated diaphragm (CD), and the amplification function is achieved using the area difference between the RD and the CD. To investigate the amplification characteristics of the mechanism, the diaphragm forces were analyzed by finite element simulations, and the dynamic model of the system was established in Simulink, based on the force balance method. Furthermore, an amplification mechanism prototype was fabricated, and the static and dynamic experiments were carried out. Combining the simulation and experiment results, the accuracy of the proposed dynamic model was verified, and the amplification characteristics of the amplification mechanism were analyzed. When the RD displacement is less than 2 mm, the force amplification effect is not obvious. When the RD displacement exceeds 2 mm, the force amplification ratio (FAR) increases with the RD displacement and decreases with the CD displacement. The maximum FAR is 2.5 with a CD displacement of 0 and an RD displacement of 6 mm. The amplification mechanism and the used research method are helpful for the application and control of the hydraulic valves. Full article

Background/Objective: Gastroesophageal reflux disease (GERD) is multifactorial and affects an increasing number of people. It is a common condition in which the stomach contents move up into the esophagus; thus, its main cause is found in the antireflux valve mechanism of the gastroesophageal junction. This consists of two sphincters, the lower oesophageal and the diaphragmatic. The disease has been related to diaphragm dysfunction, either due to the de-coordination of the diaphragms’ contractility or due to decreased strength. Breathing exercises seem to have a positive effect in this population. The aim of this study was to systematically examine the effects of inspiratory muscle training (IMT) on GERD characteristics. Methods: We conducted a systematic review of research up to April 2024 in Scopus, PubMed, and Science Direct. We included randomized controlled trials (RCTs) and clinical trials assessing the effects of IMT on GERD characteristics. Methodological quality was assessed with the PEDro scale (Physiotherapy Evidence Database) and the Newcastle Ottawa scale (NOC). Results: Among the 1984 studies identified from the search, only three studies (one study with a post-COVID-19 population and two with GERD and healthy subjects) were included in this study, as they presented a fair to high methodological quality. Significant improvements in maximal inspiratory pressure (p < 0.001) and diaphragmatic excursion (p < 0.001) were revealed in one study. No significant differences between groups were mentioned for the reflux symptoms and for LES–EGJ pressure in the studies included. Conclusions: IMT seems to provide promising effects in strengthening the antireflux valve mechanism, as it increases MIP and diaphragmatic excursion. This systematic review established a bibliographic gap for the contribution of IMT in the antireflux valve mechanism. More evidence is needed to support the importance of IMT as a non-pharmacological intervention for GERD patients. Full article

Current trends in the development of technology are linked inextricably to the increasing level of automation in technological processes and production systems. In this regard, the development of systems for supplying working fluids with adjustable pumps that have high performance characteristics, an increased service life and low operating costs is an important scientific and technical task. A primary challenge in the development of such systems lies in achieving low fluid flow rates while maintaining stable operating characteristics. This challenge stems from the fact that currently available controlled hydraulic pumps exhibit either a high cost or suboptimal life and efficiency parameters. This work focuses on the development of a plunger hydraulic pump with a small working volume. A mathematical model has been developed to investigate the characteristics, optimize the design of this pump and further expand the size range of such pumps. The solution was implemented on a computer using the dynamic modelling environment MATLAB/Simulink. In order to verify the mathematical model’s adequacy, a plunger pump prototype was built and integrated with a test bench featuring a measurement system. The test results showed higher pump efficiency and a significant reduction in hydraulic losses. An analysis of the obtained data shows that the pump is characterized by increased efficiency due to optimal flow distribution and reduced internal leakage, which makes it promising for use in hydraulic systems requiring improved operating characteristics. The developed pump has more rational characteristics compared to existing alternatives for use in water supply systems for induction superheaters. The experimental external characteristics of the developed pump are 10% higher than the external characteristics of the ULKA EX5 pump selected as an analogue, and the pressure characteristics are 65% higher. It offers production costs that are several times lower compared to existing cam-type plunger or diaphragm pumps with oil sumps and precision valve mechanisms. Additionally, it has significantly better operating characteristics and a longer service life compared to vibrating plunger pumps. Full article

This article introduces a comprehensive methodology that combines physical prototyping and computational modeling to analyze the hydrodynamics and design of a semi-direct acting solenoid valve for water applications. A transparent, injection-molded valve model was used to experimentally measure diaphragm displacement, which exhibited linear behavior at flow rates up to 10.1 L/min. Beyond this threshold, the diaphragm reached maximum displacement, constraining flow control accuracy. These experimental results informed the creation of a computational domain for detailed CFD analysis, demonstrating strong validation against experimental pressure drop data. The CFD simulations identified critical inefficiencies, such as uneven pressure distribution on the diaphragm due to inlet flow, flow imbalances, and vortex formation within the chamber and outlet channel. These issues were traced to specific design limitations. To address these design flaws, this study suggests optimizing the inlet geometry, implementing a symmetric chamber design, and modifying the outlet channel with smoother transitions to enhance flow control and improve operational efficiency. Full article

Under the trend of carbon neutrality, the adoption of electric mineral transportation equipment is steadily increasing. Accurate monitoring of the operational status of electric check valves in diaphragm pumps is crucial for ensuring transportation safety. However, accurately identifying the operational characteristics of electric check valves under complex excitation and noisy environments remains challenging. This paper proposes a monitoring method for the status of electric check valves based on the integration of Adaptive Focal Loss (AFL) with residual networks and Extreme Learning Machines (AFL-ResNet-ELMs). Firstly, to address the issue of unclear feature representation in one-dimensional vibration signals, grayscale operations are employed to transform the one-dimensional data into grayscale images with more distinct features. Residual networks are then utilized to extract the state features of the check valve, with Extreme Learning Machines serving as the feature classifier. Secondly, to overcome the issue of imbalanced industrial data distribution, a new Adaptive Focal Loss function is designed. This function focuses the training process on difficult-to-classify data samples, balancing the recognition difficulty across different samples. Finally, experimental studies are conducted using industrially measured vibration data of the electric check valve. The results indicate that the proposed method achieves an average accuracy of 99.60% in identifying four health states of the check valve. This method provides a novel approach for the safety monitoring of slurry pipeline transportation processes. Full article

With the continuous improvement in human awareness of environmental protection, energy savings, and emission reduction, as well as the vigorous development of precision machinery and process technology, energy-saving and efficient diaphragm pumps have become a hot research topic at home and abroad. The diaphragm pump is a membrane-isolated reciprocating transport pump that isolates the transport medium from the piston through the diaphragm and can be used to transport high-viscosity, volatile, and corrosive media, and the symmetrical structure can make it easier for the diaphragm pump to achieve stable operation, reduce vibration and noise, and extend the life of the pump. This paper summarizes the development and research status of diaphragm pumps in recent years, including diaphragm pump structure, working principle, category, cavitation research, wear research, fault diagnosis research, vibration and noise research, fluid–solid-interaction research, and optimum research on one-way valves and diaphragms. It also puts forward some reasonable and novel viewpoints, such as applying the theory of entropy production to explore the motion mechanism of diaphragm pumps, optimizing the performance of diaphragm pumps, using new technologies to study new materials for diaphragm pumps, and designing diaphragm protection devices. This review provides valuable references and suggestions for the future development and research of diaphragm pumps. Full article

To obtain a high flow rate, a resonant-type piezoelectric pump is designed, fabricated, and studied in this paper. The pump consists of four parts: a piezoelectric vibrator, a pump chamber, a check valve and a compressible space. The designed piezoelectric vibrator is composed of a rhombic micro displacement amplifier, counterweight blocks and two piezoelectric stacks with low-voltage drive and a large output displacement. ANSYS software (Workbench 19.0) simulation results show that at the natural frequency of 946 Hz, the designed piezoelectric vibrator will produce the maximum output displacement. The bilateral deformation is symmetrical, and the phase difference is zero. Frequency, voltage, and backpressure characteristics of the piezoelectric pump are investigated. The experimental results show that at a certain operating frequency, the flow rate and the backpressure of the piezoelectric pump both increase with the increase in voltage. When the applied voltage is 150 V_pp, the flow rate reaches a peak of 367.48 mL/min at 720 Hz for one diaphragm pump, and reaches a peak of 700.15 mL/min at 716 Hz for two diaphragm pumps. Full article

Background: Left atrial enlargement indicates severe cardiac disease. Although the gold standard for determining left atrial size is echocardiography, many veterinary practices lack the necessary equipment and expertise. Therefore, thoracic radiography is often used to differentiate cardiogenic pulmonary edema from primary respiratory diseases and to facilitate distinguishing dogs with stage B1 and B2 mitral valve degeneration. Methods: The goal was to test a new standardized method for identifying radiographic left atrial enlargement. On a lateral radiograph, a straight line was drawn from the dorsal border of the tracheal bifurcation to the crossing point of the dorsal border of the caudal vena cava and the most cranial crus of the diaphragm. If a part of the left atrium extended this line dorsally, it was considered enlarged. Echocardiographic left atrial to aortic ratio (LA:Ao) was used as a reference. Thirty-nine observers with various levels of experience evaluated 90 radiographs, first subjectively, then applying the new method. Results: The new method moderately correlated with LA:Ao (r = 0.56–0.66) in all groups. The diagnostic accuracy (72–74%) of the subjective assessment and the new method showed no difference. Conclusions: Though the new method was not superior to subjective assessment, it may facilitate learning and subjective interpretation. Full article

Fraunhofer EMFT’s research and manufacturing portfolio includes piezoelectrically actuated silicon micro diaphragm pumps with passive flap valves. Research and development in the field of microfluidics have been dedicated for many years to the use of micropumps for generating positive and negative pressures, as well as delivering various media. However, for some applications, only small amounts of fluid need to be pumped, compressed, or evacuated, and until now, only macroscopic pumps with high power consumption have been able to achieve the necessary flow rate and pressure, especially for compressible media such as air. To address these requirements, one potential approach is to use a multistage of high-performing micropumps optimized to negative pressure. In this paper, we present several possible ways to cascade piezoelectric silicon micropumps with passive flap valves to achieve these stringent requirements. Initially, simulations are conducted to generate negative pressures with different cascading methods. The first multistage option assumes pressure equalization over the piezo-actuator by the upstream pump, while for the second case, the actuator diaphragm operates against atmospheric pressure. Subsequently, measurement results for the generation of negative gas pressures down to −82.1 kPa relative to atmospheric pressure (19.2 kPa absolute) with a multistage of three micropumps are presented. This research enables further miniaturization of many applications with high-performance requirements for micropumps, achievable with these multistage systems. Full article

As the core equipment of the high-pressure diaphragm pump, the working conditions of the check valve are complicated, and the vibration signal generated during operation displays non-stationary and nonlinear characteristics. In order to accurately describe the non-linear dynamics of the check valve, the smoothing prior analysis (SPA) method is used to decompose the vibration signal of the check valve, obtain the tendency term and fluctuation term components, and calculate the frequency-domain fuzzy entropy (FFE) of the component signals. Using FFE to characterize the operating state of the check valve, the paper proposes a kernel extreme-learning machine (KELM) function norm regularization method, which is used to construct a structurally constrained kernel extreme-learning machine (SC-KELM) fault-diagnosis model. Experiments demonstrate that the frequency-domain fuzzy entropy can accurately characterize the operation state of check valve, and the improvement of the generalization of the SC-KELM check valve fault model improves the recognition accuracy of the check-valve fault-diagnosis model, with an accuracy rate of 96.67%. Full article

Automatic flushing valve (AFV) can improve the anti-clogging ability of the drip fertigation system. The minimum inlet pressure (H_amin) required for automatic closing and the maximum flushing duration (FD_max) are two important performance indexes of AFV. The existing AFV products have the problem of larger H_amin and smaller FD_max, which result higher investment and operating cost, and poor flushing efficiency. Based on the mechanical analysis of the AFV elastic diaphragm and the derivation of the FD, elastic diaphragm hardness (E), ascending channel offset distance (D), and drain hole width (W) were selected as the experimental factors, and nine AFVs were designed by L₉(3³) orthogonal test method to investigate the influence of elastic diaphragm hardness and structural parameters on the hydraulic performance of AFVs. The hydraulic performance test results showed that the H_amin of the nine AFVs ranged from 0.026 to 0.082 MPa and FD_max ranged from 36.3 to 95.7 s. H_amin was positively correlated with E and D and negatively correlated with W. FD_max was negatively correlated with E and W and tended to increase and then decrease with D. All elastic diaphragm hardness and structural parameters had a significant effect on H_amin, and E and W had a significant effect on FD_max. Based on the range analysis, two new combinations of AFV elastic diaphragm hardness and structural parameters with minimum H_amin (E = 40 HA, D = 0 mm, W = 2 mm) and maximum FD_max (E = 40 HA, D = 2 mm, W = 1.68 mm) were determined, and the corresponding H_amin was 0.022 MPa, 63.3% lower than that of the existing product, and FD_max was 116.4 s, 71.2% higher than that of the existing product. In this study, two ternary nonlinear mathematical regression models of H_amin and FD_max with elastic diaphragm hardness and structural parameters was constructed. The simulation accuracy of the models is good and can be used to quickly predict the optimal combination of AFV parameters to satisfy the actual engineering-required H_amin and FD_max. Full article

This paper proposes to improve the output performance of a piezoelectric pump by matching the resonant frequency of the resonator to the optimal operating mode of bridge-type polydimethylsiloxane (PDMS) check valves. Simulation analyses reveal that the side-curling mode of the PDMS valve is conducive to liquid flow and exhibits a faster frequency response compared with the first bending mode. The first bending resonant frequency of a beam-type piezoelectric resonator was tuned close to the side-curling mode of the PDMS valve by adjusting the weight of two mass blocks installed on both ends of the resonator, so that both the resonator and the valve could work at their best conditions. Experiments were conducted on a detachable prototype piezoelectric pump using PDMS valves with three different lengths. The results confirm that the peak flowrate at the resonant point of the pump reaches its maximum when the resonant frequencies between the resonator and the valve are matched. Maximum peak flowrates of 88 mL/min, 72 mL/min and 70 mL/min were achieved at 722 Hz, 761 Hz and 789 Hz, respectively, for diaphragm pumps using five-, four- and three-inlet-hole PDMS valves, under a driving voltage of 300 V_pp. Full article