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Hydraulic transient analysis through numerical simulations is a widely used tool for predicting and mitigating potential severe pressure oscillations due to abrupt changes in flow velocity. In practice, water hammer events typically are induced by valve operations used to control the flow rate. One of the methods to enhance the throttling capabilities of a gate valve is to install a V-shaped notch (V-port) in its opening. This provides a more linear relationship between the position of the gate and the flow rate discharging through the valve. The exact range of the flow control is determined by the V-port opening angle. Because valve-induced pressure oscillations depend on the valve characteristics, in order to accurately simulate the transient event, the specific valve closing function is required. The primary objective of this paper was to develop valve closing functions of V-port gates for all possible opening angles. Two cases were considered: the linear closure of a knife (rectangular) and a circular gate fitted with a V-port. For this purpose, the analytical formulas for calculating the relative opening area of V-shaped gate valves were derived. On this basis, valve closing functions, in the form of a power function with two variables, were developed. To analyze the influence of the V-port angle on a simulated transient event, a case study with a simple reservoir–pipeline–valve system was investigated. One-dimensional unsteady flow equations were solved using the method of characteristics. The numerical calculations conducted indicate that installing a V-notch port can result in a smoother reduction of the flow rate as the gate closes, which may dampen both maximum and minimum pressure peaks and attenuate valve-induced pressure head oscillations. The developed valve closing functions offer practical utility for practitioners engaged in hydraulic system design and operation, providing a tool for predicting hammer events induced by valve gates fitted with V-ports. [ABSTRACT FROM AUTHOR]

Flushing is a widely used method for cleaning water pipes, demanding the achievement of optimal flushing velocity for effectiveness. A prior examination of flushing condition including velocity, duration, and flow rate is crucial to minimize water and economic losses while maximizing the impact of flushing. Although simulation models are commonly employed for this purpose, they often overlook potential head loss during flow through hydrants or drain valves, compromising the effectiveness of flushing. This study investigated the impact of different simulation methods on estimating flushing conditions through hydrants and drain valves. The structural layout (minor loss coefficient) and specifications (emitter coefficient) of each flushing path were incorporated into traditional models. Applying this method to a hypothetical network and the water distribution system of G-City in Gyeonggi Province of South Korea, we compared the flushing effects of four different modeling approaches. Results reveal that drain valves tend to exhibit higher velocity than hydrants under the same conditions, mainly due to their structural layout. However, both drain valves and hydrants may experience overestimation of flow rate and velocity if the minor loss coefficient is disregarded. Practitioners should exercise caution regarding potential low flushing efficiencies. The limited numbers and locations of drain valves compared to hydrants constrain their field application, emphasizing the need for comprehensive consideration of various field conditions when developing a suitable flushing plan. [ABSTRACT FROM AUTHOR]

This paper presents a new control method for surge instability of the compressor system. Due to the importance of the active control approach in improving the efficiency of the compressor system, a new scheme based on the model predictive control (MPC) technique has been considered to control surge which gives the benefits of control signal optimization by considering the constraints on states and input. Because of designing a novel MPC by using of linear matrix inequality scheme, the optimization problem is solved in less time and with less complexity. The proposed method is able to consider the limitation of the close coupled valve actuator and also covers the uncertainty on the model. In addition, the developed model describes the nonlinear behaviour of the compressor system and handles the effects of the pipe on surge instability. Using Lyapunov theory, the stability of the closed-loop system under the proposed robust active controller is shown. The simulation results show the high pressure and high efficiency operation of the system under study in different operating conditions. [ABSTRACT FROM AUTHOR]

As a common industrial valve solution in slurry pipeline systems, Y-type slurry valves must be designed with properly shaped valve seat sealing rings to alleviate particle erosion and keep the valve operating in optimal condition. In this study, we investigate four different valve seat shapes with varying inner angles to understand the effect of the seat structure on particle erosion in Y-type slurry valves. We conducted computation fluid dynamics discrete element method simulations to analyze the impact of different valve seat shapes on the characteristics of particle-liquid two-phase flows and erosion. We also performed a detailed analysis of velocity and pressure distributions for liquid phase and particle velocity distributions as well as surface erosion on key valve components. We observed the primary erosion areas to be the back surface of the valve body, the inner surface of the valve seat, and the front surface of the valve disc, and as a result, we investigated the erosion distribution in these areas with different valve seat structures. Our simulation results indicate that the variation in particle diameter and the inner angle of the valve seat sealing ring have significant impacts on erosion in the studied areas. [ABSTRACT FROM AUTHOR]

Parallel-connected digital valve arrays are commonly utilized in the pilot stage of the proportional directional valve to enhance dynamic performance and reliability. However, when the digital valve array is driven by a digital signal, it is difficult to optimally assign the signal pulses to each valve. If the assignment is not well executed, it can significantly reduce the switching uniformity of the digital valves or lead to performance degradation of the system. In this paper, a model-based sliding mode control strategy based on the intelligent distribution of control law is proposed and successfully applied to a proportional valve driven by digital valve arrays. The intelligent distribution strategy encompasses a logic distribution algorithm and a circular sliding distribution algorithm that automatically assigns control laws to different valves based on the rolling of the PWM signal cycle. Experimental results confirm that the proposed strategy not only simultaneously reduces the total number of valve switches and enhances the switching uniformity among the valves, but also adapts to the variation in the number of valves. The proposed strategy is not limited to the application of digital valve arrays, it is also applicable in other fields of multi-actuators driven by digital signals, and can simultaneously improve the control accuracy, lifetime, and maintenance friendliness. • A digital proportional valve is proposed, where the pilot stage consists of fixed orifices and digital valve arrays. • The intelligent distribution strategy is designed based on a logic distribution and a circular sliding distribution. • The proposed MSMC with intelligent distribution can be adapted to DVAs with any number of valves. [ABSTRACT FROM AUTHOR]

The positioning control of the hydraulic support pushing system in the fully mechanized mining face is the key technical support to realize intelligent mining. The opening and closing of the existing support switch reversing valve will cause a sudden change in the system pressure and flow under the conditions of high pressure and large flow, which will affect the life of the components, the precision, and stability of the actuator movement. To solve the problem, the structure of a two-speed buffer valve for the hydraulic support pushing circuit is designed. Firstly, the pushing system is analyzed theoretically, and the characteristics of the flow field in the valve and the applicable working conditions are simulated. Then, an experimental platform was built to test the improvement effect of the two-speed buffer valve on the characteristics of the pushing system. Finally, the pressure, flow, and positioning characteristics of the two-valve series pushing system under different flow rates are studied by the test results. The research results show that when the two-speed buffer valve is used, the pressure and velocity change thresholds of the system are reduced, which reduces the pressure fluctuation in front of the valve and its effect on the system pressure. At the same time, under a different system flow, the downstream pressure characteristics of the valve are improved, and the steady-state pressure anti-interference is enhanced. The positioning error of the system is reduced under different flow rates. The effectiveness of the scheme is verified by the test, which provides a basis for the optimization of the downhole valve control cylinder scheme and the subsequent valve. [ABSTRACT FROM AUTHOR]

The greatest losses during gas transportation occur in the elements of shut-off valves, the operating parameters of which, among other things, depend on the thickness and hardness of the protective coating of the ball plugs. The study of the parameters of nickel–phosphorus and chrome coatings on ball plugs of serially produced shut-off valves, including control of their thickness and hardness, was carried out. Based on the test results, deviations in the actual parameters of coatings from the requirements of technological documentation were revealed, the necessity of their complex control was substantiated, recommendations on the choice of methods and equipment were formulated, and the main provisions of the test methodology were developed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department 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 integrated gate-commutated thyristor (IGCT) has the advantages of high voltage, high current, high reliability, and low manufacturing costs and has the potential to replace thyristor devices in the field of high-voltage direct current (HVDC) transmission. Over time, the development and manufacture of IGCT devices, drivers, and valve bodies have gradually matured, but the modeling and control technology of HVDC systems based on IGCT needs further research. This review aims to discuss the research status of key technologies of HVDC system modeling and control based on the IGCT in recent years, including the development of HVDC systems and the application potential of the IGCT, the efficient simulation and modeling technology of the IGCT HVDC system, and the key problems of HVDC system control technology based on the IGCT. At the same time, according to the author's point of view, the existing problems and difficulties are extracted, and the next development ideas are clarified. [ABSTRACT FROM AUTHOR]

Herein, the design, modeling, and validation of high‐flow, fluid‐driven, membrane valves tailored specifically for applications in soft robotic systems are described. Targeting the piping problem in hyper‐actuated soft robots, two fluid‐driven membrane valve designs that can admit flows of up to 871 mg s−1$871 \textrm{ } \textrm{ } \text{mg} \textrm{ } \left(\text{s}\right)^{- 1}$ while weighing less than 20 g$false$ are introduced. A mathematical model to predict fluid flow by representing the displacement of the membrane as a scalar quantity influenced by the balance of pressures applied across the valve's ports is established. The model incorporates six parameters with direct physical relevance, enhancing its usefulness in valve design and system integration. In an experimental validation, flow rates with deviations within 4% are predicted and the onset of flow is correctly identified with an error rate of less than 1%. In addition, applications of these valves for flow amplification and for the creation of a fluid‐driven oscillator are experimentally demonstrated. This research contributes to the advancement of soft robotics by providing a tool for designing, optimizing, and controlling fluid‐driven systems and it lays the groundwork for the future development of embedded, fluid‐controlled valve networks that can be used to realize hyper‐actuated soft robotic systems. [ABSTRACT FROM AUTHOR]

Soft robots have been advancing rapidly, but their control is still limited by rigid control elements. Soft valves offer a solution to this problem by enabling soft robots to no longer rely on rigid control elements. They have become an emerging research topic in soft robotics. However, with a large number of publications on soft valves, it may be challenging for researchers to quickly grasp the advanced technology related to soft valves. To address this issue, this article summarizes the current state of development in soft valves. The design principles and applications of soft valves in terms of structures and materials are discussed, along with the modeling ideas for soft valves. Finally, the current challenges faced by soft valves are outlined, and potential solutions to these problems are proposed. [ABSTRACT FROM AUTHOR]

Background Aortic insufficiency (AI) is often encountered in transcatheter aortic valve replacement (TAVR) but is only rarely haemodynamically significant. Even more uncommon is the occurrence of intraprosthetic AI that often leads to haemodynamic compromise requiring additional therapeutic intervention. Case summary An 85-year-old female with severe aortic stenosis underwent elective TAVR with a size 23 mm SAPIEN 3 Ultra RESILIA (S3UR) valve. After implantation, the patient developed hypotension. Transthoracic as well as transoesophageal echocardiogram identified significant transvalvular AI. Persistence of AI led the team to consider a TAV-in-TAV strategy. Before a second valve system could be inserted, the patient's blood pressure improved and AI resolved spontaneously. The patient was discharged and recovered with no AI on follow-up imaging studies. Discussion This is the first reported case of significant intraprosthetic AI with the new S3UR in our literature search as of writing. The new S3UR valve has several improvements from previous generations designed to increase valve area and durability as well as decreasing the incidence of paravalvular and intraprosthetic leaks. A stuck leaflet was inferred as the cause of the intraprosthetic AI, and the improved design with excessive expansion may have led to this. Unlike previous case reports, intraprosthetic AI resolved without further intervention likely due to the turbulence of flow releasing the stuck leaflet. Cautious observation prevented the need for a TAV-in-TAV for a rare and possibly catastrophic complication. [ABSTRACT FROM AUTHOR]

The maximum radial size of the conventional three-bit four-way electromagnetic cartridge valve is greater than the largest containable size of the fluid control valve used for downhole robots. This paper proposes two kinds of solutions to reduce the radial dimension of the three-bit four-way electromagnetic insertion valve: one is to reduce the radial arrangement of the coil and increase the axial arrangement of the coil, and the other is to reduce the diameter of the moving iron core to reduce the winding radius of the coil. Using the theoretical model established in the following text, a simulation experiment was conducted. The results show that the movement of the valve spool is basically completed within 30 ms. Then, a matching experiment on the electromagnetic insertion valve was designed and conducted. The experimental results show that the opening time of the solenoid valve on the left coil is about 52 ms, and the opening time of the solenoid valve on the right coil is about 44 ms. The reaction time of the valve spool is suitable for the practical application of the solenoid valve. The significance of this paper is the reduced radial size of the three-bit four-way electromagnetic insertion valve. These improvements have reduced the size of downhole drilling robots, which facilitates the application of downhole drilling robots in narrower environments. [ABSTRACT FROM AUTHOR]

The microstructure and eutectic precipitates in a novel 15Cr–30Ni–2Ti–3Cu valve alloy produced by electroslag remelting, and the evolution of eutectic precipitates and dissolution kinetics of Laves phase during homogenization were studied. The microhardness of the valve alloy reaches a value of 247.8 HV after the homogenization at 1273 K (1000 °C)/6 hours + 1413 K (1140 °C)/5.5 hours, and the hardness uniformity reaches a maximum after the homogenization at 1223 K (950 °C)/6 hours + 1413 K (1140 °C)/5.5 hours. The secondary dendrite arm spacing in the as-cast ingot is 48.75 μm, and the area fractions of Fe2Ti Laves phase, (Ti,Nb)C, Sigma phase and γ′-Ni3(Ti,Al) phase are 2.83, 0.92, 0.09 and 0.01 pct, respectively. The Laves phase dissolved obviously even at the lowest homogenization temperature 1223 K (950 °C). The eutectic (Ti,Nb)C phase begins to dissolve at 1223 K (950 °C), and the dissolution degree is much lower than that of Laves phase. The homogenization degree of alloying elements after single-stage homogenization is much lower than that of dual-stage homogenization. The dissolution kinetics of Laves phase established based on the Johnson-Mehl-Avrami-Kolmogorov model shows that the activation energy of Laves phase in alloy is 275.8 kJ/mol. The reverse diffusion of Mo from Laves phase into matrix is the determining step of Fe2Ti Laves phase dissolution. [ABSTRACT FROM AUTHOR]

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center 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.)

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.)

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.)

Pressure reducing valves (PRVs) are essentially used to reduce operational pressures in water distribution systems (WDSs) to minimize water leakage. However, water age in a WDS is an important variable describing the water quality and should be kept as low as possible. Therefore, the aim of this study is to investigate the possibility and potential of simultaneously minimizing both pressure and water age by using PRVs. To determine the optimal location and setting of PRVs, a mixed-integer nonlinear programming (MINLP) problem is formulated with minimization of the sum of the weighted total water age and pressure as the objective function, where the weighting factor can be defined by the user's preference. The equality constraints consist of the hydraulic equations and water age functions to describe pressure and water age in the distribution network, while the inequality constraints ensure them in the defined operating ranges, respectively. Applying the proposed approach to two case studies, the results show that both water age and pressure can indeed be significantly reduced by the optimized position and setting of the PRVs. [ABSTRACT FROM AUTHOR]

During the operation of combine harvesters, the cutting platform height is typically controlled using manual valve hydraulic systems, which can result in issues such as delays in adjustment and high labor intensity, affecting both the quality and efficiency of the operation. There is an urgent need to enhance the automation level. Conventional methods frequently employ single-point measurements and lack extensive area coverage, which means their results do not fully represent the terrain's variations in the area and are prone to local anomalies. Given the inherently undulating terrain of farmland during harvesting, a control strategy that does not adjust for minor undulations but only for significant ones proves to be more rational. To this end, a sine wave superposition model was established to simulate three-dimensional ground elevation changes, and an area array LiDAR was used to collect 8 × 8 data for the header height. The effects of mounds and stubble on the measurement results were analyzed, and a dynamic process simulation model for the solenoid valve core was developed to analyze the on/off delay characteristics of a three-position four-way electromagnetic directional valve. Moreover, a physical model of the hydraulic system was constructed based on the Simscape module in Simulink, and the Bang Bang switch predictive control system based on position threshold was introduced to achieve early switching of the electromagnetic directional valve circuit. In addition, an automatic control system for cutting platform height was designed based on an STM32 microcontroller. The control system was tested on the hydraulic automatic control test rig developed by Shanxi Agricultural University. The simulation and experimental results demonstrated that the control system and strategy were robust to output disturbances, effectively enhancing the intelligence and environmental adaptability of agricultural machinery operations. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the effects of bladder neck incision (BNI) and primary valves ablation on long-term kidney and bladder function in children with posterior urethral valves (PUV) and bladder neck hypertrophy (BNH). Patients and methods: From 1997 to 2016, a total of 1381 children with PUV were referred to our tertiary hospital. Of these patients, 301 PUV patients with bladder neck hypertrophy need concurrent BNI and valve ablation. All patients were followed up every 3–6 months on regular basis in first 2 post-surgical years and annually then after. The paired t-test and chi-square test were used to perform statistical analysis with p value < 0.05 defined as the level of significance. Results: Mean age at diagnosis was 7.22 ± 2.45 months (ranging from 7 days to 15 months) with a mean follow-up of 5.12 ± 2.80 years. The incidence of hydronephrosis was decreased from 266 (88.3%) at the baseline to 73 (24.3%) patients in long-term follow-up. At baseline, 188 (62.5%) patients were diagnosed with VUR, which decreased to 20 (6.6%) individuals at the end of follow-up. Bladder and renal function were improved in follow-ups following concomitant PUV ablation and BNI. No Myogenic failure was depicted in all patients with BNH. No ureteric reimplantation was needed during the two decades follow-up. Conclusion: Simultaneous valve ablation with BNI may present further profits in children with PUV and BNH particularly cases of BNH with poor bladder function at the time of presentation. This method can improve the results of urodynamic and imaging studies after the surgery. We hypothesize every child with PUV presentation who has concurrent vesicoureteral reflux, CKD or persistent hydrourethronephrosis may suffer from secondary bladder neck obstruction. This secondary bladder outlet obstruction must be managed through BNI as the surgical relief. [ABSTRACT FROM AUTHOR]

Mollusc shells are among the most abundant and well-preserved organisms in sediments worldwide, but their shells are usually subject to fragmentation due to exposure time in the TAZ, which compromises their preservation potential. The shell strength of valves from life and death assemblages from the sandy beaches of Santa Clara (37°50′49″S, 57°30′16″W) and Mar Chiquita (37°44′45″S, 57°25′1.5″W) on the Bonaerense coast, southwest Atlantic Argentina, was analysed to capture the effect of taphonomic processes over time and to determine how intrinsic properties and taphonomic variables influence their shell strength. To achieve this, the mechanical resistance profile of the bivalve Eucallista purpurata was assessed using point load and microindentation tests, and the mineralogical composition and organic matter content of the shell, as well as morphological variables, were measured. We concluded that, as expected, shells from life assemblages were more resistant to compression than those from death assemblages, but surprisingly, right valves were more resistant to compression than left valves in both Mar Chiquita and Santa Clara death assemblages. No differences were observed between broken and unbroken shells. [ABSTRACT FROM AUTHOR]

The large flow rate proportional poppet valve (PPV) finds widespread use in high‐power hydraulic systems. However, the indispensable dead‐zone nonlinearity that guarantees the safe shut‐off of the PPV will cause a tracking lag when a command goes outside the dead‐zone. The lag should be properly solved in a controller, which is a highlight of this study. Simultaneously, achieving high tracking precision in a PPV is necessary to meet the demands of advanced hydraulic systems. In this study, a practical nonlinear controller based on an integral separated disturbance observer is proposed to improve the performance of a PPV. In particular, the lag could be alleviated and the high tracking precision achieved simultaneously by enabling or disabling a disturbance observer in the proposed controller. A separation coefficient is proposed for the disturbance observer to detach the integral action from the controller and avert the deep input saturation of the pilot stage. Additionally, the command filtering technology is applied to the nonlinear controller to improve its interference resisting capacity in the industrial environment. The stability and effectiveness of the proposed controller are proved in theory and verified by experiments. [ABSTRACT FROM AUTHOR]

Valve control for patients feeding saline is a sensitive issue. Such a valve is used to control the amount of important fluid entering the body. In this paper, we present an intelligent method based on fuzzy logic (FL) to deliver drugs and nutrients to patients through intravenous catheters. The proposed method is called intelligent saline controlling valve (ISCV) and relies on three inputs and two outputs. Specifically, the fluid's drip, pressure, and the number of available bubbles are the three-valve inputs that control the two outputs which are the opening and closing. In other words, the ISCV controls the feeding saline for medical purposes. The obtained results show the success of the proposed method. [ABSTRACT FROM AUTHOR]

Optofluidic regulation of blood microflow in vivo represents a significant method for investigating illnesses linked to abnormal changes in blood circulation. Currently, non-invasive strategies are limited to regulation within capillaries of approximately 10 μm in diameter because the adaption to blood pressure levels in the order of several hundred pascals poses a significant challenge in larger microvessels. In this study, using laser-induced microbubble formation within microvessels of the mouse auricle, we regulate blood microflow in small vessels with diameters in the tens of micrometers. By controlling the laser power, we can control the growth and stability of microbubbles in vivo. This controlled approach enables the achievement of prolonged ischemia and subsequent reperfusion of blood flow, and it can also regulate the microbubbles to function as micro-pumps for reverse blood pumping. Furthermore, by controlling the microbubble, narrow microflow channels can be formed between the microbubbles and microvessels for assessing the apparent viscosity of leukocytes, which is 76.9 ± 11.8 Pa·s in the in vivo blood environment. The proposed design of in vivo microbubble valves opens new avenues for constructing real-time blood regulation and exploring cellular mechanics within living organisms. [ABSTRACT FROM AUTHOR]

The machining quality of the sealing surface of a triple-eccentric butterfly valve is crucial to its sealing performance. Especially, the measuring of sealing surface size is the key to assessing the machining quality. Due to the special structure of the triple-eccentric butterfly valve, the sealing surface size of the triple-eccentric butterfly valve is difficult and inaccurate to measure in position, which makes it difficult to ensure the machining quality of the triple-eccentric butterfly valve sealing surface. This will affect the sealing performance of the triple-eccentric butterfly valve and result in poor bidirectional sealing, non-interchangeability, and lower machining productivity of the bodies and discs. Based on the above problems, this paper proposes a new measuring method for sealing surface size, i.e., an in-position measuring method of point-replacing surface. The reliability of the method is analyzed and proved from the level of the design principle of the triple-eccentric butterfly valve. Further, the tooling fixture and in-position measuring device of sealing surface size are designed and manufactured based on the measuring method of the point-replacing surface. Different from the existing assembling boring process, this paper designs and manufactures new boring tooling fixtures and develops an integrated process of measuring and machining. After the preliminary measuring and machining test, the reproducibility of the results was good, and parts interchangeability and bidirectional sealing could be realized. And the application of this machining process significantly shortened the machining time and increased the machining efficiency by 25%. [ABSTRACT FROM AUTHOR]

This article proposes a heating method based on heat pump technology to address the large amount of low-grade waste heat generated by a certain type of ultra-high voltage direct current (UHVDC) converter valve. Thermal performance calculations for two systems, a basic vapor compression heat pump system (BVCHPS) based on thermal expansion valve throttling and an ejector-enhanced heat pump system (EEHPS) are analyzed. The research results show that the EEHPS exhibits superior COP and exergy efficiency when generating hot water above 80 °C using a heat source below 50 °C. Additionally, mathematical modeling analysis identifies optimal structural parameters such as nozzle throat diameter, throat area ratio, and nozzle outlet diameter for the ejector in its design state. The low-temperature waste heat recovered from the UHVDC converter valves can be further used in engineering applications such as heating, refrigeration, seawater desalination, and sewage treatment. [ABSTRACT FROM AUTHOR]

AbstractHematogenous metastasis occurs when cancer cells detach from the extracellular matrix in the primary tumor into the bloodstream or lymphatic system. Elucidating the response of metastatic tumor cells in suspension to the flow conditions in lymphatics with valves from a mechanical/fluidic perspective is necessary. A physiologically relevant computational model of a lymphatic vessel with valves was constructed using fully coupled fluid–cell–vessel interactions to investigate the effects of lymphatic vessel contractility, valve properties, and cell size and stiffness on the variations in magnitude and gradient of the flow-induced wall shear stress (WSS) experienced by suspended tumor cells. Results indicated that the maximum WSSmax increased with the increments in cell diameter, vessel contraction amplitude, and valve stiffness. The decrease in vessel contraction period and valve aspect ratio also increased the maximum WSSmax. The influence of the properties of the valve on the WSS was more significant among the factors mentioned above. The maximum WSSmax acting on the cancer cell when the cell reversed the direction of its motion in the valve region increased by 0.5–1.4 times that before the cell entered the valve region. The maximum change in WSS was in the range of 0.004–0.028 Pa/µm depending on the factors studied. They slightly exceeded the values associated with breast cancer cell apoptosis. The results of this study provide biofluid mechanics-based support for mechanobiological research on the metastasis of metastatic cancer cells in suspension within the lymphatics. [ABSTRACT FROM AUTHOR]

High-speed on/off valve acts as critical enabling component of digital hydraulics, which has been challenging the traditional hydraulic system by providing efficient and effective hydraulic control solutions. The high-speed on/off valve that ideally fits the digital hydraulic system is expected to achieve fast response and long stroke with affordable energy consumption. This not only requires developing advanced actuation mechanism but also demands extensive study on the driving strategy. This study focuses on investigating the Peak-and-hold driving strategy applied to a novel high speed on/off valve-energy coupling actuated valve (ECAV), in order to achieve target performance with optimized energy consumptions. This work has developed an electro-mechanical coupled physics model based on commercial finite element solver COMSOL. This model helps to investigate the performance of ECAV under different peak-and-hold driving parameters and thereby recommend the optimal peak-and-hold driving strategy. Then, the experimental testing on the prototype ECAV has been conducted to validate the simulated performances. The measurement results showed that the prototype ECA using the optimal peak & hold solution demonstrated significant advantage in energy saving targeting at response of 10 ms for 1.5 mm stroke, especially compared to a typical step input signal. [ABSTRACT FROM AUTHOR]

Chamaecrista rotundifolia (C. rotundifolia) is a perennial herb of leguminosae, which increasingly being grown as a forage in China. In our search for original bioactive metabolites from Cassia plants, the phytochemical reinvestigation of the C. rotundifolia was carried out, which led to the isolation of three new (1–3) and six known (4–9) chromones. Their structures were confirmed by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1–9 were evaluated for their anti-rotavirus activities, and the results revealed that compounds 1–9 exhibited potential anti-rotavirus activities with therapeutic index (TI) valves in the range of 12.0 ∼ 20.2, respectively. [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.)

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.)

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.)

A polymer valve seat is an essential component of ball valves. However, a gas pipeline valve leakage during the gas or oil transportation process causes major issues. Therefore, the fine finishing of the polymer valve seat is important. This work describes the effect of the magnetorheological finishing (MRF) process on the surface characteristics of the polymer valve seat. To achieve a finely finished polymer valve seat surface, the best process parametric combination of current, workpiece rotational, and tool rotational speed are obtained using the response surface methodology. The optimum process parameters are further used to enhance surface characteristics (including surface roughness, microhardness, and surface morphology) through fine finishing. Using the optimum process conditions, the surface roughness was reduced to 110nm from 570nm in 140min of finishing on a 4878mm2 surface area of the polymer valve seat. The circularity of the valve seat surface’s dimensional correctness is investigated further. The current MRF process can fine-finish the polymer valve seat surface consistently, resulting in improved surface characteristics and functional performance. [ABSTRACT FROM AUTHOR]

Laojun 4 Well is a high sulfur gas well located on the edge of Puguang, after acid fracturing, The formation pressure coefficient is low, before putting into production, the temporary plugging is necessary, but there has two Circulation valves stalled within 1m,the normal temporary plugging agents cannot smoothly pass through the inner diameter of the circulation valve. In view of the above problems, a polymer gel temporary plugging agent has been developed and successfully applied in Laojun 4 Well. Laboratory and field experiments show that the polymer gel temporary plugging agent has a plugging pressure of 27 MPa and a validity period of 15 days at 130 ℃, with the high plugging removal rate, it can block the gas escape from the wellbore. After being put into production, the output is about 1.2 million m3 /d, the effect of site application is super. [ABSTRACT FROM AUTHOR]

Bioclaustrations are among the best ways that parasitic associations are preserved. A new bioclaustration, Haplorygma productidophilia csp. nov., is here described from the ventral interior of the Carboniferous productid brachiopod Eomarginifera lobata. The location and morphology of the structures in the ventral valve differ from the structure in the dorsal valve, suggesting that two different organisms infested the shells of Eomarginifera lobata. It is possible that whether it was ventral or dorsal valve was an important selection criterion for the infesting organisms, which were likely parasites. The proportion of infested productids was low in the population (5.8%). This low infestation rate could indicate that productids had effective methods for resisting parasites, or that the parasites were ineffective in spreading through the brachiopod population. [ABSTRACT FROM AUTHOR]

Purpose: To build, train, and assess the artificial neural network (ANN) system in estimating the residual valve rate after endoscopic valve ablation and compare the data obtained with conventional analysis. Methods: In a retrospective cross-sectional study between June 2010 and December 2020, 144 children with a history of posterior urethral valve (PUV) who underwent endoscopic valve ablation were enrolled in the study. MATLAB software was used to design and train the network in a feed-forward backpropagation error adjustment scheme. Preoperative and postoperative data from 101 patients (70%) (training set) were utilized to assess the impact and relative significance of the necessity for repeated ablation. The validated suitably trained ANN was used to predict repeated ablation in the next 33 patients (22.9%) (test set) whose preoperative data were serially input into the system. To assess system accuracy in forecasting the requirement for repeat ablation, projected values were compared to actual outcomes. The likelihood of predicting the residual valve was calculated using a three-layered backpropagating deep ANN using preoperative and postoperative information. Results: Of 144 operated cases, 33 (22.9%) had residual valves and needs to repeated ablation. The ANN accuracy, sensitivity, and specificity for predicting the residual valve were 90.75%, 92.73%, and 73.19%, respectively. Younger age at surgery, hyperechogenicity of the renal parenchyma, presence of vesicoureteral reflux (VUR), and grade of reflux before surgery were among the most significant characteristics that affected postoperative outcome variables, the need for repeated ablation, and were given the highest relative weight by the ANN system. Conclusions: The ANN is an integrated data-gathering tool for analyzing and finding relationships among variables as a complex non-linear statistical model. The results indicate that ANN is a valuable tool for outcome prediction of the residual valve after endoscopic valve ablation in patients with PUV. [ABSTRACT FROM AUTHOR]

Background: For a long time, the hypertrophied tonsils impact on velopharyngeal closure has been a point of concern. Objectives: To identify the alterations in the velopharyngeal valve (VPV) closure patterns following adenotonsillectomy in Arabic-speaking children, to predict the incidence of complications as nasal regurgitation or open nasality. Patients and methods: This observational prospective research was performed on 100 patients, with hypertrophied adenoid and tonsils, who were collected from outpatient clinic of Benha University Hospitals. All cases underwent preoperative laboratory investigations, otorhinolaryngology examination and video-nasoendoscopy and speech assessment before and after adenotonsillectomy. Results: The VP closure pattern was insignificantly different between both groups. However, the Nasality was significantly different among the 3 studied periods (P<0.001). There was no relation between gender and VP closure pattern preoperatively and 1 month after surgery. Regarding the postoperative nasality (hypernasality), the most prevalent observed VP closure patterns were both coronal and circular ones. Conclusions: The coronal pattern of closure of the VPV is the most prevalent type, which remains even postoperatively, also the type of closure has no significant value in predicting outcoming hypernasality. [ABSTRACT FROM AUTHOR]

In this study, we employed geometric morphometrics (GMs) to analyze the shell shape differences among two mass-selected strains of bay scallops (red shell strain (RS) and black shell strain (BS)) and a control group (CG). The results revealed distinct shell shape differences corresponding to shell coloration, with the black shell strain displaying a more elliptical shell compared to the red shell strain. Additionally, the umbonal angle of the red shell strain was smaller than that of the black shell strain, indicating that the black shell strain had a more favorable jet direction that could enhance swimming capabilities. To evaluate the model's performance in practical applications, leave-one-out cross-validation was carried out on the two shell strains and one control group. The results demonstrated discrimination accuracy rates of 67.44%, 47.62%, and 68.18% for the BS strain, RS strain, and CG, respectively. Similarly, for the right valves, the discrimination accuracy rates were 62.79%, 50.00%, and 75.00% for the BS strain, RS strain, and CG, respectively. [ABSTRACT FROM AUTHOR]

A new freshwater benthic diatom species, Gomphonema incrassatasp. n. (Mohan and Prabha), is described from the Walayar Dam, Palakkad district, Kerala, India. The description is based on data derived from light and scanning electron microscopic studies. The main features of Gomphonema incrassata are: valves are weakly heteropolar; linear-lanceolate; head pole is bluntly round; basal or foot pole is sharply rounded; and the frustule is club-shaped and flexed (bent) in the girdle view. In addition, the analysed physicochemical characteristics revealed that Walayar Dam is moderately polluted, due to various human activities. The newly identified freshwater diatom species adds to the knowledge of diatom diversity in the Indian subcontinent. [ABSTRACT FROM AUTHOR]

The utilization of liquid-cooled plates has been increasingly prevalent within the thermal management of batteries for new energy vehicles. Using Tesla valves as internal flow channels of liquid-cooled plates can improve heat dissipation characteristics. However, conventional Tesla valve flow channels frequently experience challenges such as inconsistencies in heat dissipations and unacceptably high levels of pressure loss. In light of this, this paper proposes a new type of Tesla valve with partitions, which is used as internal channel for liquid-cooled plate. Its purpose is to solve the shortcomings of existing flow channels. Under the working conditions of Reynolds number equal to 1000, the neural network prediction-NSGA-II multi-objective optimization method is used to optimize the channel structural parameters. The objective is to identify the optimal structural configuration that exhibits the greatest Nusselt number while simultaneously exhibiting the lowest Fanning friction factor. The variables to consider are the half of partition thickness H, partition length L, and the fillet radius R. The study result revealed that the optimal parameter combination consisted of H = 0.25 mm, R = 1.253 mm, L = 0.768 mm, which demonstrated the best performance. The Fanning friction factor of the optimized flow channel is substantially reduced compared to the reference channel, reducing by approximately 16.4%. However, the Nusselt number is not noticeably increased, increasing by only 0.9%. This indicates that the optimized structure can notably reduce the fluid's friction resistance and pressure loss and slightly enhance the heat dissipation characteristics. [ABSTRACT FROM AUTHOR]

• The article introduces a novel semi-empirical model for a TEV operating with R290. • No prior experimental work was found involving TEV operating with R290 in DX-SAHP. • The article emphasizes a careful data collection process encompassing 150 experiments. • The multiple linear regression resulted in a R² of 0.9648 with predictions not exceeding more than 15 % deviation. • The model was applied and compared with 44 experiments from the literature, resulting in a deviation of less than 15 %. The expansion device plays a crucial role in the operation of heat pumps and refrigeration systems, making its study integral to advancements in the fields of refrigeration and heating. Among various expansion devices, the Thermostatic Expansion Valve (TEV) stands out due to its rapid response time and mechanical nature, which grants it high control capacity over refrigerant superheating. In this study, was developed a semiempirical mathematical model for a TEV incorporated in a DX-SAHP utilizing R290. The research was carried out in an experimental way, conducted using a fully instrumented DX-SAHP. A series of experiments tested different operational modes for water heating, subject to varying solar radiation intensities. A uniform methodology collected operational parameters, resulting in 150 experiments. The semiempirical model creation involved combining basic equations from the literature describing TEV operation and formulating an equation using multiple linear regression based on experimentally evaluated parameters. These parameters included solar radiation incidence, inlet and outlet pressures, and superheating degree. The regression model achieved an adjustment higher than 96 %. Combining this regression with equations suggested by previous researchers, resulted in a model with an adjustment exceeding 94 %. Furthermore, this study culminated in the derivation of a generalized model primed for broad application across various heat pump configurations for water heating purposes. Notably, the model underwent rigorous validation across a separate set of experiments, reaffirming its reliability and versatility. While excelling in steady-state operations, the model's transient data analysis falls short, as intended. [ABSTRACT FROM AUTHOR]

This article proposes an improved adaptive finite time command filtered controller for high-precision motion control of electro-hydraulic servo systems. During the controller design process, the effects of parameter uncertainty, unmodeled disturbances, and dead zone uncertainty in the system are effectively addressed by integrating parameter adaptive laws and disturbance estimation laws. By extending the system states, this strategy eliminates the need for the controller to rely on the first-order derivative of the tracking trajectory, making it applicable in tracking non smooth curves. Through Lyapunov stability analysis and comparative simulation experiments, it is shown that even in the presence of unmodeled disturbances, unknown system parameters, and unknown dead zone characteristics in the system, the developed controller can still achieve adjustable neighborhood tracking errors around the origin in a finite time. • A controller for an electro-hydraulic servo system that comprehensively considers multiple nonlinear factors is proposed. • Improved instruction filtering controller, weakened derivative requirements, and expanded application scenarios. • The proposed controller can achieve tracking error convergence within the specified error band within a finite time. • This article considers the nonlinear factors caused by the dead zone of the servo valve in the system. [ABSTRACT FROM AUTHOR]

Summary: Rock drilling jumbo is an important large construction machine used for tunneling construction, and its automation has an urgent demand in engineering. However, the electro‐hydraulic system of the rock drilling jumbo has strong parameters uncertainties and some dynamics that are hard to model accurately, which causes certain challenges for designing model‐based high‐performance control algorithms. To solve these challenges, a parameter adaptive based neural network sliding mode control algorithm is proposed to enhance control performance of the electro‐hydraulic system. The parameter adaptive law is developed to estimate unknown parameters of the system, the neural network is applied for compensating unmodeled dynamics, and then the final control law is designed by sliding mode control method, and the stability demonstration of the closed‐loop system is given. In the simulations, the effectiveness of the designed parameter adaptive law is verified. Extensive comparison experiments are performed on a real rock drilling jumbo driven by proportional valves, the experimental results demonstrate that the developed control algorithm obviously improves the control precision of hydraulic cylinder of the rock drilling jumbo compared with the traditional sliding mode and PID control algorithm, thus the designed control algorithm can be expanded and applied for general hydraulic servo control mechanism. [ABSTRACT FROM AUTHOR]

• Commercial-of-the shelf (COTS) space qualified solenoid valves for small satellite missions are financially unviable. • Thrusters control spacecraft attitude, the response time, and parameters of the solenoid valve is critical in mission design. • A mathematical model was developed to find the optimized geometrical configuration of the solenoid valve. • This paper presents a practical solution for designing custom solenoid valves. • The developed mathematical model validated using COTS space qualified solenoid valves. Small satellites and spacecrafts use propulsion systems to stabilize their attitude, control orientation and deorbit it at the end of the mission life. The flow and thrust of the liquid propulsion system are controlled by the control valve, typically operated by solenoid. According to recent literature, space-qualified solenoid valves are expensive and financially non viable, especially for small satellite missions. In this paper, a detailed methodology is presented to design the solenoid valve dedicated for small satellites. This study includes design criteria focusing on geometrical configuration. The dynamic, and electro-magnetic models are used to characterize the solenoid valve. Dynamic modelling helps to determine the response time of valve, affecting the thruster minimum impulse bit. The physical dimensions of the designed solenoid valve are smaller than those available in commercial off-the shelf (COTS) solenoid valves. However, the efficacy of the proposed design is proven effective with the COTS space grade valve specifications, and it shows that the proposed valve consumes less power than the conventional valves. Finally, it is worth noting that despite their modest and compact physical dimensions, the proposed valve are ideal for small satellite missions. [ABSTRACT FROM AUTHOR]

Hydroponics is a method of growing plants without soil. Hydroponics, a subset of hydro culture, is a growing plant without soil, using mineral nutrient solutions in a water solvent. In soil less culture especially, hydroponics, the problem of regular maintenance of nutrient solution and required technical knowledge. The automation in hydroponics further helps to boom up the hydroponic cultivation. Automated nutrient regulation in hydroponics environment with automatic nutrient feed technology was developed and tested in the present study. The experiment was carried out an automated controlling and regulation of pH, TDS, temperature in polyhouse hydroponic system using Arduino-Uno controller, solenoid valves containing nutrients, water, pH-up, and pH-down and sensors. In this study, the sensors are connected to Arduino-Uno controller in which liquid crystal display (LCD) of Arduino-Uno circuit controls and regulates the system based on the coding which has been programmed previously. Calibration was done for all the parameters in the automated system. TDS and pH values of nutrient solution were recorded by using TDS and pH sensor probes respectively were fed to Arduino which adjusts the values, if required, through actuators. The prototype model was able to monitor and control the pH and TDS of hydroponic water in the required range with high accuracy. [ABSTRACT FROM AUTHOR]

Direct-acting relief valves are important pressure-control components in hydraulic systems; however, noise problems are now common. This study aimed to reduce and numerically analyze the valve cavitation and noise using the Zwart–Gerber–Belamri (ZBG) model with the Ffowcs Williams and Hawkings (FW–H) model to optimize the design based on the sound field perspective. First, a direct-acting relief valve flow field model was established to determine the relationship between the seat structure and the degree of cavitation through a CFD (Computational Fluid Dynamics) simulation. Second, sound field analysis was conducted based on the cavitation and non-cavitation flow fields, respectively, and the resulting noise levels were compared. Finally, prototypes of the relief valve were manufactured, and noise levels between the original and optimized valves were compared. The results revealed that cavitation within the relief valve generated noise while optimizing the valve seat cone angle suppressed this phenomenon, thereby reducing the noise emitted by the optimized valve by 18.2 dB compared to the original valve. These findings can serve as a guide for designing and optimizing direct-acting relief valves. [ABSTRACT FROM AUTHOR]

The loss of steerage in maritime vessels often stems from main engine failures, as expounded in the present article. The focal incident involves a cascading engine breakdown initiated by a single exhaust valve fault. Subsequent consequences encompass the fragmentation of the second exhaust valve, structural damage to the engine components, including the head and piston, cracking of valve seats, and the inadvertent entry of cooling water into a cylinder. The ensuing plastic strain on the cylinder surface, coupled with valve fragments infiltrating the turbocharger, leads to additional, albeit minor, damage. Notably, the high degree of plastic strain obfuscates the original features of the cracked elements, necessitating the author to delineate a hypothetical cause and progression of the destruction process. In the conclusive remarks, the author underscored the paramount importance of continuous engine operation monitoring and meticulous fault diagnosis to uphold the safety standards of maritime transport. [ABSTRACT FROM AUTHOR]

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The initial valves of two Cymbella species are observed under a scanning electron microscope, and the perizonium ultrastructure of Cymbella is revealed for the first time. The perizonium is composed of alternate nodes and internodes and lacks transverse perizonium bands. Four new species, Cymbella apiculatophora sp. nov., C. hunanensis sp. nov., C. juglandis sp. nov. and C. menyuanensis sp. nov., are described using light and scanning electron microscopy based on epilithon samples collected from rivers in Hunan and Qinghai Provinces, China. Cymbella menyuanensis is a typical Cymbella species that closely resembles species in the group around C. cymbiformis Agardh, the type species of the genus. Cymbella apiculatophora is similar to C. sinensis Metzeltin & Krammer, while Cymbella hunanensis is closer to the C. hustedtii Krasske group. The last species, C. juglandis, has a cymbelloid valve outline, an obscured intermissio, internal occlusions of the areolae, dorsally deflected distal raphe fissures and a divided apical pore field at each apex, and it does not appear to belong to any group. In addition, new observations on C. cf. excisiformis Krammer and C. hustedtii are reported. The current concept of the genus Cymbella does not represent a monophyletic group as shown by molecular phylogenetic analyses. However, these analyses are still at the preliminary stage and are not yet sufficient to support a complete revision of the genus. Thus, although extremely diverse ultrastructural features are observed in the six Cymbella species investigated in this paper, we prefer to keep them within Cymbella at this moment for the sake of nomenclatural stability. [ABSTRACT FROM AUTHOR]

This study has developed adaptive synergetic control (ASC) algorithm to control the angular position of moving plate in the electronic throttle valve (ETV) system. This control approach is inspired by synergetic control theory. The adaptive controller has addressed the problem of variation in systems parameters. The control design includes two elements: the control law and adaptive law. The adaptive law is developed based on Lyupunov stability analysis of the controlled system, and it is responsible for estimating the potential uncertainties in the system. The effectiveness of the proposed adaptive synergetic control has been verified by numerical simulation using MATLAB/Simulink. The results showed that the ASC algorithm could give good tracking performance in the presence of uncertainty perturbations. In addition, a comparison study has been made to compare the tracking performance of ASC and that based on conventional synergetic control (CSC) for the ETV system. The simulated results showed that the performance of ASC outperforms that based on CSC. Moreover, the results showed that the estimation errors between the actual and estimated uncertainties are bounded and there is no drift in the developed adaptive law of ASC. [ABSTRACT FROM AUTHOR]