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Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock 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.)

The results of studying an application model of unsteady flow through the reed valve assembly of a two-stroke piston engine are presented. The main goal was to develop and validate a model based on the check valve calculation scheme in the ALLBEA software package. The principles of modeling the valve motion dynamics in conjunction with a one-dimensional model of gas dynamics, as well as the algorithmic presentation of calculations for their implementation in the package, are briefly discussed. An approach to valve model identification and the proposed method for adjusting the model coefficients are considered. For the identification and validation of the model the data obtained from a single-cycle experimental setup were used, in which flow through the reed valve with finite amplitude waves in the pipeline was organized. The conducted research contributes to the analysis and optimization of processes in pipelines, pumps, and engines, promotes the development of applied models, software tools, and calculation methods in the specified areas.

Given that two-phase closed thermosiphons (TPCT) are a prevalent and efficacious means of heat transfer. However, non-condensable gas (NCG) may potentially impact the heat transfer performance of the aforementioned devices. Nevertheless, the theoretical analysis of heat transfer in TPCT containing NCG is not fully comprehensive and therefore requires further supplementation by means of relevant experiments. This paper presents the development and experimental investigation of a theoretical heat transfer model for a TPCT containing NCG. The research encompasses the optimal fluid-filling ratio of R22 and R410a working fluid and the impact of NCG on heat transfer in the condenser section of TPCT. Experimental findings indicate that TPCT with R22 and R410a working fluids at a fluid-filling ratio of 60% and 50%, respectively, demonstrate excellent isotherm and heat transfer efficiency. The presence of NCG affects the condenser section heat transfer process of the vapor, leading to a 2 °C decrease in the average temperature of the condenser section of the TPCT (Tca). In comparison with the TPCT without NCG, it was observed that an increase in the mass of NCG from 0.0097 to 0.0197 mol resulted in a reduction in the effective length of the condenser section (La) and effective heat transfer rate (κ) of R22 TPCT. The decrease in La was 75.1 mm, while the decrease in κ was 15.02%. Furthermore, at the same NCG mass, the effective heat transfer rate of R410a TPCT is evidently superior to that of R22 TPCT. The NCG in the TPCT can be removed by using a check valve. Nevertheless, this will result in a reduction in the fluid-filling ratio of the TPCT. The temperature of the R410a TPCT containing 0.0197 mol NCG with a fluid-filling ratio of 50% is comparable to that observed in fluid-filling ratio of 40% after the NCG is exhausted. [ABSTRACT FROM AUTHOR]

Elements of microfluidic systems created by 3D printing offer numerous advantages, such as rapid manufacturing, low cost, and the ability to create complex 3D channel topologies. Their parameters and performance can be quickly adjusted by editing the model loaded into the printer. However, the mechanical properties of polymers used for printing are often poorly documented and can significantly change over time due to aging, relaxation, or creep effects, leading to unexpected behaviour of 3D-printed devices. To address this issue, we performed a complete mechanical characterization of the samples made by 3D printing, including stress relaxation and creep tests, at different time intervals after printing. The determined properties of the material allowed us to model the mechanical and hydrodynamical performance of the 3D-printed microfluidic device, which we demonstrate using an example of a fully printed check valve specially developed for use in microfluidic systems. This approach allows easy quantitative evaluation of the optimal production cycle and lifetime of 3D-printed microfluidic devices. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the industrial production environment, strong noise and other environmental stimuli result in similarities in the characteristics of different faults in the diaphragm pump check valve, making it difficult for traditional deep learning methods to accurately identify the valve's fault status. To solve this problem, a method combining supervised contrastive learning and hybrid attention residual neural network (HA-ResNet) was proposed for fault diagnosis of diaphragm pump check valves. Firstly, the attention mechanism was introduced into the residual neural network to enhance the network's learning capabilities. The weights of important but weak features were adaptively adjusted by the attention mechanism, and the suppression of useful information through identity transformations was reduced. Secondly, a weighted “supervised contrastive loss( SCL) + cross-entropy (CE) loss” was proposed to adjust the distances between different fault states of the check valve. The classification boundaries for different fault states were clarified by this method and the interference of noise or environmental stimuli was reduced. Finally, the effectiveness and stability of the method combining supervised contrastive learning and HA-ResNet were verified using real measurement data. The results show that the average accuracy of supervised contrastive learning and HA-ResNet fusion method reaches 99. 3% on the validation set of the diaphragm pump check valve. Comparing with other fault diagnosis methods, supervised contrastive learning and HA-ResNet fusion method has advantages in diagnostic accuracy and stability. The reliability of this method for fault diagnosis under noise interference conditions has been verified. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) 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.)

Given that two-phase closed thermosiphons (TPCT) are a prevalent and efficacious means of heat transfer. However, non-condensable gas (NCG) may potentially impact the heat transfer performance of the aforementioned devices. Nevertheless, the theoretical analysis of heat transfer in TPCT containing NCG is not fully comprehensive and therefore requires further supplementation by means of relevant experiments. This paper presents the development and experimental investigation of a theoretical heat transfer model for a TPCT containing NCG. The research encompasses the optimal fluid-filling ratio of R22 and R410a working fluid and the impact of NCG on heat transfer in the condenser section of TPCT. Experimental findings indicate that TPCT with R22 and R410a working fluids at a fluid-filling ratio of 60% and 50%, respectively, demonstrate excellent isotherm and heat transfer efficiency. The presence of NCG affects the condenser section heat transfer process of the vapor, leading to a 2 °C decrease in the average temperature of the condenser section of the TPCT (Tca). In comparison with the TPCT without NCG, it was observed that an increase in the mass of NCG from 0.0097 to 0.0197 mol resulted in a reduction in the effective length of the condenser section (La) and effective heat transfer rate (κ) of R22 TPCT. The decrease in La was 75.1 mm, while the decrease in κ was 15.02%. Furthermore, at the same NCG mass, the effective heat transfer rate of R410a TPCT is evidently superior to that of R22 TPCT. The NCG in the TPCT can be removed by using a check valve. Nevertheless, this will result in a reduction in the fluid-filling ratio of the TPCT. The temperature of the R410a TPCT containing 0.0197 mol NCG with a fluid-filling ratio of 50% is comparable to that observed in fluid-filling ratio of 40% after the NCG is exhausted.

Due to the operation conditions and system characteristics of the essential service water system of nuclear power plants, water hammer pressure fluctuates in each transient process. In order to further analyze the characteristics of the water hammer and the harm this can cause to system equipment, this paper uses one-dimensional transient computing software to simulate the water hammer characteristics of the system under different operating conditions and at different water levels. The instantaneous pressure data of water hammer in the essential service water system were used as input conditions for fatigue analysis of components, and the fatigue damage of at-risk parts was calculated. The results show that the pressure fluctuation due to single pump outage is greater than that due to single pump start-up and the start-up of double pumps. The maximum pressure of the system under the design flood level is greater than that of other water levels, and the maximum pressure of the system under each working condition is 3.87 MPa. The most at-risk part of the system pressure fluctuation is the return valve, followed by the valve after a bend in a pipe and the tee pipe fitting. In the whole system, the joint of the main branch of a tee pipe experiences the greatest fatigue damage, and the theoretical fatigue life is 127.55 years. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock 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.)

Background: Traumatic pulmonary pseudocysts are a rare complication resulting from pulmonary contusion associated with blunt chest trauma. Case presentation: A 17-year-old male patient underwent emergency surgery for hemostasis of a traumatic lung injury caused by a car accident. Because the bleeding was from the peripheral lung, partial resection was performed with an automated suture machine. A routine leak test (positive pressure ventilation at 20 cm H2O) was performed as a precautionary measure. Postoperative imaging revealed rapid enlargement of a comorbid traumatic pulmonary pseudocyst. The collapse of the obliterating bronchus due to the accident and the intraoperative positive pressure ventilation for the air leak test were considered to have caused the rapid enlargement of the traumatic pulmonary pseudocyst. A thoracoscopic right lower lobectomy was performed on postoperative day 5. The patient had an uneventful postoperative course. Conclusions: To our knowledge, this is the first report of a rapidly enlarging traumatic pulmonary pseudocyst captured on preoperative and postoperative computed tomography. It would serve as a learning point for respiratory surgeons. These results suggest that when patients with traumatic pulmonary pseudocysts are operated on under general anesthesia, excessive positive pressure ventilation may cause a rapid expansion of the pulmonary pseudocyst. [ABSTRACT FROM AUTHOR]

The potable water in residential hydraulic networks is measured using volumetric meters. However, when the water carries air bubbles or pockets through the pipes, the accuracy of the meter readings is reduced, which can negatively impact the billing that users pay for their water consumption. A check valve accessory exists that reduces the size of these air bubbles to correct the meter readings and improve the service experience. However, the device has only been tested for networks with relative pressures higher than 275.79 kPa. This research proposes to characterize the hydraulic behavior of the accessory through an experimental procedure in which the operating conditions are similar to those found in water networks in Latin America, where the networks have relative pressures lower than 275.79 kPa. The study found that the accessory significantly reduces the coefficient of loss for velocities greater than 1 m/s. The use of the device is suggested in flow regimes with Reynolds numbers close to 20,000 for operating conditions of temperatures close to 25 °C and residential pipes with an internal diameter of 20.9 mm and a flow velocity between 1.3 m/s and 1.78 m/s. This condition allows it to operate with minimal local energy loss and a low coefficient of loss, providing an improved service experience. [ABSTRACT FROM AUTHOR]

Abstract An air-supplement plasma synthetic jet (PSJ) actuator increases the air supplemental volume in the recovery stage and improves the jet energy by attaching a check valve to the chamber of a conventional actuator. To explore the flow control effect and mechanism of the air-supplement actuator, via particle image velocimetry experiments in a low-speed wind tunnel, the flow field and boundary layer characteristics of a two-dimensional airfoil surface under different actuation states were compared for different attack angles and jet orifices. The experimental results show that, compared with the conventional actuation state, the jet energy of the air-supplement PSJ is higher and the indirect mixing effect of the counter-vortex sequence produced by the jet-mainstream interaction is stronger. Furthermore, the boundary layer mixing effect is better, which can further suppress flow separation and improve the critical flow separation attack angle. Moreover, increasing the jet momentum coefficient can enhance the flow control effect. The findings of this study could provide guidance for the flow control application of air-supplement PSJs.

We have reported the rare case of an intermittent endoleak via an aneurysm–venous fistula (AVF). An 89-year-old woman had experienced postoperative sac expansion 6 years after she had undergone endovascular aneurysm repair. During aneurysmorrhaphy, we detected a small AVF, which was the source of the endoleak responsible for the aneurysmal sac expansion. This AVF had a check valve-like mechanism that allowed the inflow of blood from the iliac vein to the sac when the venous pressure exceeded the endotension. Our case has demonstrated the occurrence of an AVF after endovascular aneurysm repair that had resulted in an endoleak that was invisible on imaging studies and the presence of endotension.

The poor opening dynamic characteristics of molten salt check valves, used in concentrating solar thermal systems, constitute the main cause of valve disc oscillation and low pressure difference difficulty in opening during molten salt delivery. A molten salt swing check valve is designed to meet the requirements of high-temperature and high-pressure sealing and anti-crystallization flow channels. A transient dynamics model of the valve motion components is established, dynamic mesh and UDF (user-defined function) techniques are used to simulate the non-constant flow of hot molten salt and the opening process of the check valve and to analyze the dynamic characteristics of the opening process. Topological optimization of the valve motion components is proposed for the first time in order to improve the opening performance of the check valve, and the topological optimization of the valve motion components is based on the solid isotropic material penalty (SIMP) model with the variable density method and thermal–fluid–mechanical coupling method. The design is also verified for the dangerous working condition of a molten salt hammer. The results show that the mass of the valve motion component is reduced by 57.76% after optimization while meeting the requirements of strength and stiffness. The optimized molten salt check valve achieves a larger angle and faster opening, the full opening angle is increased by 6°, the positive resting pressure difference of the valve is reduced by 5 kPa, the minimum opening pressure difference is reduced by 8.9 kPa, the optimized flow characteristics are smoother, and the valve disc oscillation problem is avoided. The study provides a method for researchers to use to optimize the design of a molten salt swing check valve and its dynamic characteristics for concentrating solar power, which is of great significance in efforts to improve the stability of the molten salt transport system. [ABSTRACT FROM AUTHOR]

Check valves are key components required to ensure that fluid flows in one direction. Internal cross-port leakage is a common fault that affects the service performance of check valves. Cross-port leakage occurs due to defects in the valve spool. Early detection of this fault and its root cause is important to prevent downtime and subsequent costs. This research presents a multi-scale signal enhancement method based on spool impact and pressure signal analysis for leakage identification and its root causes. The impact signals obtained by accelerometers attached to the valve body are segmented from the entire vibration signal to capture the variations in the inherent characteristics of the valve. Subsequently, wavelet packet decomposition and reconstruction are performed to extract the energy distribution and energy entropy of signals. The time-frequency domain is used to extract features for leakage identification faults. Correlation analysis was applied to select 45 sensitive features out of 105 features. The performance of the method was verified using the RCYCS-G experimental hydraulic platform, and the recognition rate of four modes was found to be 100 % accurate. The proposed method accurately identifies the root causes of leakage in the check valve, lays a foundation for leakage rate prediction, and has significant engineering application value in predictive maintenance. [ABSTRACT FROM AUTHOR]

To improve the plunger gas lift efficiency, a modified plunger was developed by adding a check valve to the downhole positioner in the Changqing Gas Field. However, the transient flow behavior of the plunger lift with check valve is unclear owing to the lack of a reliable method. Therefore, in this study, a simplified transient mechanistic model based on the law of conservation of momentum and mass is proposed to simulate the comprehensive dynamic process of a plunger-lift system. The results of the proposed method exhibited a high coincidence with that of the accumulated gas and liquid production of gas Well-1 in one cycle, and the relative errors were 2.11% and 4.29%, respectively. The calculation results demonstrate that the plunger lift with check valve can effectively prevent the flow of liquid to the bottom of the well, reduce the bottom hole flow pressure, and increase the productivity of gas well during the shut-in period. The efficiency of the plunger lift with check valve was enhanced with an increase in the volume of the accumulated liquid unloaded from the bottom of gas wells. Additionally, for the plunger lift with check valve, the production peak value was higher and the instantaneous gas production peak value was lower in comparison with the conventional plunger. After the plunger reached the wellhead, the instantaneous fluid production of the conventional plunger was relatively unstable than that of the plunger lift with check valve. A certain distance should be maintained from the bottom of the well in the case of the positioner with check valve. If the positioner is placed at the bottom of the tubing, the difference between the lift efficiency of the plunger with check valve and conventional plunger is small, and lower than that of the conventional plunger. The installation position of the downhole positioner in a gas well should be below the accumulated liquids level and should maintain a certain distance between the positioner and bottom of the well (200 m). The results of this study enhance the understanding of the operation mechanism of the plunger lift with check valve, and unloading of the accumulated liquids from the bottom of gas wells. [ABSTRACT FROM AUTHOR]

• Using a single-loop, unidirectional slug flow oscillating (pulsating) heat pipe model with the heat transfer controlled by conduction through the slug-deposited liquid film and a simple evaporation rate model relating the slug velocity and heat flux, the overall thermal resistance/conductance is predicted with an analytic expression. • The results are also compared and validated with a more complete, statistical 1-D heat, mass, momentum transport simulation results. • The prediction offers an upper bound on conductance for the available experiments with R134a, butane, acetone, and water. A simple analytic model for the thermal resistance of the oscillating (pulsating) heat pipe (OHP or PHP) is proposed and verified. It is based on the Taylor liquid film formed by moving liquid slugs, film heat conduction, and interfacial evaporation/condensation. It uses a unidirectional flow (characteristic of use of check valves) in a horizontal (no gravity effect) single-loop OHP to derive a relationship between the slug velocity and heat flux. The model predictions are verified with experiments. In addition, the CFD results for the slug-deposited liquid film thickness δ l support that the transition from laminar flow (at Reynolds number, Re D = 2000, D is the diameter) tends toward a constant film thickness regime, previously observed (experimentally) and correlated. Prior direct 1-D simulations also show that at yet higher Re D (3700), a constant slug velocity regime is reached. The evaporator specific thermal resistance, A e R e = A e /G e = δ l /k l , (k l is liquid thermal conductivity) and the total OHP thermal resistance R, is predicted and compared with the current and available related experimental results (for R134a and butane) with good agreement. The suggested ideal high heat flux (constant film thickness δ l , c limit for Re D > 2000) dimensional total ideal resistance is R = 1 G = δ l , c k l (1 A e + 1 A c ) , with δ l , c = 120 D La − 2 / 3 , providing a lower limit on R (upper limit on G). The filling ratio, flooding, and local dryout effects causing deviation from the ideal conductance are addressed. This analytical model can be extended to non-circular channels by using the hydraulic diameter. [Display omitted] [ABSTRACT FROM AUTHOR]

The unidirectional flow of nanofluids holds paramount importance in numerous nanofluidic applications. However, there remains a void in the practical implementation of a nano check valve specifically designed for ensuring such unidirectional flow. In this work, a nano check valve consisting of a diaphragm and a valve seat is designed and its forward opening and reverse shutoff processes are investigated using molecular dynamic simulations. Additionally, the effects of the modified groups of the diaphragm of the nano check valve are studied. The results demonstrate that the nano check valve can be opened efficiently under a certain forward differential pressure. Besides the differential pressure, the interaction between diaphragm and water molecules contributes to the opening process. Conversely, the non-bonding interaction between diaphragm and the valve seat prevents the opening. The reverse shutoff simulations reveal that the reverse shutoff function can be achieved under the backward pressure even when the nano check valve is firstly opened. It is observed that the ratio of hydroxyl to hydrogen groups on the edge of diaphragm has a significantly effect on the opening pressure due to the non-bond interaction of diaphragm and water molecules. This suggests that the opening pressure of the nano check valve could be regulated by changing the modifier groups. [Display omitted] [ABSTRACT FROM AUTHOR]

The delivery and distribution of fluid have wide applications in biomedicine, the fine chemical industry, pharmaceutical research, and other fields. However, existing fluid delivery and distribution systems often suffer from issues such as large size, excessive noise generation, and high-power consumption, rendering them unsuitable for convenient applications. Here, a wheel-shaped valve piezoelectric micropump with a size of only 10 mm*10 mm*1 mm is proposed and a prototype is prepared. The vibration mode, operating principle, and the liquid flow of the micropump are analyzed by finite element method. The output liquid (distilled water) flowrate of the pump is approximately 15 mL/min, and the maximum pump distilled water pressure can reach 100 KPa. The results indicate that the performance of the micropump is consistent with the analysis results, which shows its potential application in the field of portable devices and medical. [Display omitted] • A micro piezoelectric pump with simple structure, size of only 10 mm*10 mm *1 mm was designed. • The vibration mode, operating principle, and the liquid flow of the micropump are analyzed by finite element method. • Provide a new idea or a new method for piezoelectric micro pumps to achieve high flow and pressure. [ABSTRACT FROM AUTHOR]

In this study, a simple manufacturing method was developed for fabricating a multifunctional capacitive flow meter (CFM), which can act as a check valve for flow channels. By using three-dimensional (3D) printing technology, a hybrid advanced manufacturing process is realized. As the gas flows in the forward direction, the initially closed polymer membrane opens and allows airflow. The flexible and dielectric membrane is normally closed. It opens in response to the airflow direction and changes the capacitance according to the airflow rate. The sensing performance of four different CFMs were characterized according to the thickness of the membrane. From an analysis of the static and transient responses, the sensing range, sensitivity, and signal-to-noise ratio were calculated and compared. The CFM with a 600 $\mu \text{m}$ thick membrane was adopted as the sensing component for a human respiratory (inhalation and exhalation) monitoring system as one of the applications. The 3D printed system successfully measured the respiratory rate and tidal volume (~442.3 ml), supporting the applicability of CFMs in diverse fields such as human healthcare, mass flow controllers, and smart wearable devices.

An air-supplement plasma synthetic jet (PSJ) actuator increases the air supplemental volume in the recovery stage and improves the jet energy by attaching a check valve to the chamber of a conventional actuator. To explore the flow control effect and mechanism of the air-supplement actuator, via particle image velocimetry experiments in a low-speed wind tunnel, the flow field and boundary layer characteristics of a two-dimensional airfoil surface under different actuation states were compared for different attack angles and jet orifices. The experimental results show that, compared with the conventional actuation state, the jet energy of the air-supplement PSJ is higher and the indirect mixing effect of the counter-vortex sequence produced by the jet-mainstream interaction is stronger. Furthermore, the boundary layer mixing effect is better, which can further suppress flow separation and improve the critical flow separation attack angle. Moreover, increasing the jet momentum coefficient can enhance the flow control effect. The findings of this study could provide guidance for the flow control application of air-supplement PSJs. [ABSTRACT FROM AUTHOR]

Introduction: Ovarian granulosa cell tumor is a relatively rare tumor that accounts for 2-5% of malignant ovarian tumors. This tumor progresses slowly and may recur late in life. Case presentation: A 70-year-old woman was admitted to our hospital with a left secondary pneumothorax due to metastatic lung tumors of granulosa cell tumor. Reports of secondary pneumothorax due to granulosa cell tumor are rare. Thoracoscopic suturing and pleurodesis using talc were effective in the treatment of this pneumothorax. Conclusions: We experienced a rare case of secondary pneumothorax due to multiple pulmonary metastases of granulosa cell tumor. It should be noted that pulmonary metastasis of granulosa cell tumor can lead to secondary pneumothorax. [ABSTRACT FROM AUTHOR]

Due to the complicated engineering operation of the check valve in a high−pressure diaphragm pump, its vibration signal tends to show non−stationary and non−linear characteristics. These leads to difficulty extracting fault features and, hence, a low accuracy for fault diagnosis. It is difficult to extract fault features accurately and reliably using the traditional MPE method, and the ELM model has a low accuracy rate in fault classification. Multi−scale weighted permutation entropy (MWPE) is based on extracting multi−scale fault features and arrangement pattern features, and due to the combination of extracting a sequence of amplitude features, fault features are significantly enhanced, which overcomes the deficiency of the single−scale permutation entropy characterizing the complexity of vibration signals. It establishes the check valve fault diagnosis model from the twin extreme learning machine (TELM). The TELM fault diagnosis model established, based on MWPE, aims to find a pair of non−parallel classification hyperplanes in the equipment state space to improve the model's applicability. Experiments show that the proposed method effectively extracts the characteristics of the vibration signal, and the fault diagnosis model effectively identifies the fault state of the check valve with an accuracy rate of 97.222%. [ABSTRACT FROM AUTHOR]

The check valve is the core part of high-pressure diaphragm pumps. It has complex operation conditions and has difficulty characterizing fault states completely with its single feature. Therefore, a fault signal diagnosis model based on the kernel extreme learning machine (KELM) was constructed to diagnose the check valve. The model adopts a multi-feature extraction method and reduces dimensionality through kernel partial least squares (KPLS). Firstly, we divided the check valve vibration signal into several non-overlapping samples. Then, we extracted 16 time-domain features, 13 frequency-domain features, 16 wavelet packet energy features, and energy entropy features from each sample to construct a multi-feature set characterizing the operation state of the check valve. Next, we used the KPLS method to optimize the 45 dimension multi-feature data and employed the processed feature set to establish a KELM fault diagnosis model. Experiments showed that the method based on KPLS optimal feature selection could fully characterize the operating state of the equipment with an accuracy rate of 96.88%. This result indicates the high accuracy and effectiveness of the multi-feature set constructed with the KELM fault diagnosis model. [ABSTRACT FROM AUTHOR]

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs 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.)

The article presents the information on different structural types of refractory products used for blowing metal in steel-teeming ladles and the key factors influencing their efficiency. The influence of basic refractory materials and their manufacture quality on the technological performance of the products is also evaluated. Based on continuous monitoring of the metal blowing efficiency, the structural types of argon-conducting units were determined, which are most consistent with the requirements of the technological process of cleaning steel in the steel-teeming ladles of the oxygen converter shop of the Magnitogorsk Iron and Steel Works PJSC. [ABSTRACT FROM AUTHOR]

Radiation therapy for patients with prostate cancer is preferably provided with a full urinary bladder. Full bladder can potentially move the small intestine out of the radiation treatment regions, and results in decreased small bowel radiation dose and gastrointestinal toxicity. Maintaining consistent bladder filling during computerized tomography simulation scan used for treatment planning and at daily radiation treatments is challenging. Here we present an in-development urinary catheter with a floating balloon that drains the bladder only when urine reaches to a prespecified level, and review current methods used in clinic to ensure consistent bladder filling. These includes bladder filling protocols, ultrasound scanning and biofeedback techniques.

The hydraulic system is the backbone of industrial, construction, and agricultural machines. Its high-power density and efficiency execution make it the preferred choice for high-energy applications. This manuscript presents the evidence against the statement, Whenever the system runs to its full capacity, hydraulic oil heats up more as compared to partial loads.“ Our experimental study on Injection Molding Machine (IMM) hydraulic system tries to reshape the above statement by presenting the fact where we came across that lower system loading case is causing higher hydraulic oil temperatures than full loading.” The concern started when the machine at lower speeds results in frequent shutdowns due to increasing operating temperature high alarm!“ This article presents the study to resolve the stated issue completely. For the design evolution, a systematic diagnostic approach is displayed based on the six-sigma and the associated mathematical model. Our study concludes with an approach to find the self-balancing system for the case where the temperature increase is must be due to the higher rate of heat addition than the rate of heat rejection. Presented learning can be equally extended for the other fields of interest, as care should be taken to understand the passive system losses, which can result in elevated temperatures due to lower cooling capabilities.

The poor opening dynamic characteristics of molten salt check valves, used in concentrating solar thermal systems, constitute the main cause of valve disc oscillation and low pressure difference difficulty in opening during molten salt delivery. A molten salt swing check valve is designed to meet the requirements of high-temperature and high-pressure sealing and anti-crystallization flow channels. A transient dynamics model of the valve motion components is established, dynamic mesh and UDF (user-defined function) techniques are used to simulate the non-constant flow of hot molten salt and the opening process of the check valve and to analyze the dynamic characteristics of the opening process. Topological optimization of the valve motion components is proposed for the first time in order to improve the opening performance of the check valve, and the topological optimization of the valve motion components is based on the solid isotropic material penalty (SIMP) model with the variable density method and thermal–fluid–mechanical coupling method. The design is also verified for the dangerous working condition of a molten salt hammer. The results show that the mass of the valve motion component is reduced by 57.76% after optimization while meeting the requirements of strength and stiffness. The optimized molten salt check valve achieves a larger angle and faster opening, the full opening angle is increased by 6°, the positive resting pressure difference of the valve is reduced by 5 kPa, the minimum opening pressure difference is reduced by 8.9 kPa, the optimized flow characteristics are smoother, and the valve disc oscillation problem is avoided. The study provides a method for researchers to use to optimize the design of a molten salt swing check valve and its dynamic characteristics for concentrating solar power, which is of great significance in efforts to improve the stability of the molten salt transport system.

The design of a micropump with high performance and excellent reliability on thermal management still remains a challenge for electronic cooling. The performance of a piezoelectric pump with 3 chambers connected in series on thermal management was investigated for electronic cooling in this study. Two S-shaped channel heat sinks and the piezoelectric pump with 3 chambers connected in series were combined to form a loop cooling system. With water as the pumping medium, the tested pump has a flow rate most up to 690.6 ml/min at an input voltage of 220 V and an input frequency of 110 Hz. Suitability of the system has been demonstrated through simulation analysis and experimental verification for temperature control. A temperature reduction of 3 °C of CPU could be achieved at 250 mL/min flow rate generated by the piezoelectric pump with 3 chambers connected in series. [ABSTRACT FROM AUTHOR]

Heat pipes are widely used in thermal management due to their high heat transfer coefficient. However, traditional heat pipes conduct heat bidirectionally, depending on the temperature at both ends of the pipe. This can lead to the transfer of external heat back into the system at high ambient temperatures, reducing system performance and potentially damaging devices. To overcome this drawback, a thermal diode with thermal rectification in the horizontal direction based on a novel check valve and modified wick is proposed, and its thermal performances are experimentally investigated. Results show that the thermal diodes with filling ratio of working fluid less than 40% can achieve thermal rectification. The best thermal rectification coefficients of filling ratio of 10%, 20%, 30%, 40% and 50% are 3.422, 4.528, 4.238, 2.601 and 1.336, respectively. The thermal diode with filling ratio of 20% can reach the maximum thermal rectification ratio (4.528) under the heating power of 20W. [ABSTRACT FROM AUTHOR]

The free-piston Stirling generator (FPSG) holds great promise as a thermal-to-electrical conversion device for space applications. However, heat transfer remains a critical factor obstructing its scalability to high power levels. In this study, we propose a high-power FPSG with a gas-compressing self-circulating heat exchanger (GSHX) that utilizes high-pressure helium as the heat transfer fluid, enhancing the reliability of the heat exchanger. By incorporating a built-in gas-compressing device and check valves, the performance degradation caused by significant pressure fluctuations in the resonant self-circulating heat exchanger is effectively addressed. Through detailed simulations, we demonstrate the principle feasibility of the GSHX with a 4 m heat transfer loop, achieving an output electric power of 11 kW and a thermal-to-electric efficiency of 20.4%. Furthermore, the GSHX exhibits similar operating characteristics to traditional FPSGs, as we analyze the systems' stability under various operating conditions. Importantly, our findings reveal that the acoustic characteristics of the loop play a pivotal role in system performance, with operating parameters exhibiting periodic variations related to helium wavelength. By carefully optimizing system parameters, GSHX with a long loop length of 29 m can achieve comparable performance to systems with shorter loops. This study provides valuable insights into the operational characteristics and performance optimization of the GSHX, offering a comprehensive heat transfer solution for long-distance, high-efficiency, and highly reliable applications of high-power FPSGs in the space domain. • Novel FPSG with gas-compressing self-circulating heat exchangers proposed. • System achieves 11 kW output power, 20.4% thermal-to-electric efficiency. • Acoustic characteristics of loop decisively impact system performance. • Optimization enables comparable performance for extended loop lengths. [ABSTRACT FROM AUTHOR]

Due to the complicated engineering operation of the check valve in a high−pressure diaphragm pump, its vibration signal tends to show non−stationary and non−linear characteristics. These leads to difficulty extracting fault features and, hence, a low accuracy for fault diagnosis. It is difficult to extract fault features accurately and reliably using the traditional MPE method, and the ELM model has a low accuracy rate in fault classification. Multi−scale weighted permutation entropy (MWPE) is based on extracting multi−scale fault features and arrangement pattern features, and due to the combination of extracting a sequence of amplitude features, fault features are significantly enhanced, which overcomes the deficiency of the single−scale permutation entropy characterizing the complexity of vibration signals. It establishes the check valve fault diagnosis model from the twin extreme learning machine (TELM). The TELM fault diagnosis model established, based on MWPE, aims to find a pair of non−parallel classification hyperplanes in the equipment state space to improve the model’s applicability. Experiments show that the proposed method effectively extracts the characteristics of the vibration signal, and the fault diagnosis model effectively identifies the fault state of the check valve with an accuracy rate of 97.222%.