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A valve block is a key component and main load-bearing structural member in the integrated installation of fluid control components and sensors, which are widely used in hydraulic systems in aerospace and other fields owing to their compact structures and ease of integration. However, hydraulic valve blocks that are manufactured using conventional processes are bulky and inefficient in terms of material use and add complexity to the configuration of vertically intersectional internal flow channels, which form eddy currents and result in potentially serious pressure losses. Moreover, their auxiliary process holes increase the risk of hydraulic oil leakage, thereby considerably decreasing the reliability of the product. This study proposes a comprehensive process for practical structural optimization and additive manufacturing process combining selective laser melting (SLM), generative design, and SLM process simulation to optimize the structure of an aerospace engine servo actuator hydraulic valve block. The weight of the hydraulic valve block was reduced by 35.9% by employing the generative design, which could reduce the cost of space transport. The actual manufacturing process of the hydraulic valve block was considered by combining SLM and post-machining. Furthermore, additive process simulations were used to evaluate printing risks and defects, optimize the printing schemes, and improve the product quality. [ABSTRACT FROM AUTHOR]

Discarded tempering lubricants retained significant reuse potential, making their recycling a vital step in reducing resource wastage and wastewater treatment costs in the strip steel industry. Hence, developing an accurate, rapid evaluation indicator for recycled fluid concentration was essential for facilitating this process. Research showed that among common evaluation indicators for metal fluids, three—electrical conductivity, refractive index and total base number (TBN)—due to their high linear correlation with tempering lubricant concentration (R2 > 0.995), could be utilised to monitor the dynamic changes in the concentration of tempering lubricants. Subsequent experiments on reused tempering lubricants revealed that electrical conductivity, significantly altered by iron powder (7%–24% variance), and refractive index, impacted by hydraulic oil (3% deviation), highlighted contaminant challenges; yet, filtration effectively mitigated iron powder's effect on TBN. Finally, A 17‐day reused tempering lubricants simulation demonstrated consistent effectiveness of the three indicators in monitoring the need to update tempering lubricant concentration. However, in terms of sensitivity, precision, and particularly stability and relative mean deviation, the TBN concentration evaluation indicator outperformed, with TBN (3.38%) < Refractive Index (7.92%) < Electrical Conductivity (11.05%). This indicates the TBN method's superior stability over conductivity and refractive index methods, with its accuracy deviation below 2%, making it a stable, simple and reliable metric worthy of broader adoption. [ABSTRACT FROM AUTHOR]

Hydraulic spool valves may clamp under the action of sensitive particles when working in hydraulic oils that contain solid particles, which will then bring about a devastating detriment to the machines. According to the failure statistics of hydraulic systems organized by ISO, more than 80% of the operational failures of hydraulic systems are caused by fluid contamination, and particulate contamination is the most important factor causing spool valve stagnation. In this paper, we considered various factors, including the material, size, and concentration of particles and the spool postures, and built a systematic spool clamping mechanical model. A device was designed to measure the spool valve friction under the action of particles. The influence of particle material, concentration, and size on the friction force of spool valves was investigated. By experiments, we measured the spool clamping force under the action of each single factor and then fitted the datum quantity of spool clamping force and the empirical equation of pulsating quantity. The study results demonstrate three types of non-ideal postures of spools in a valve hole, which are off-center, tilting, and off-center with tilting. Those three postures can engender clamping risk zones with different ranges inside the clearance between spool valves, increasing the risk of spool clamping. The kind of particles is found to have a certain but limited impact on the spool clamping force. Usually, particles with a higher elastic modulus can trigger a larger spool clamping force, which is in line with the theoretical equation. Within a certain range, the probability density distribution of particle size tallies with the normal distribution function, where the "sensitive particles" take up 0.7–1 of the clearance between spool valves. A higher particle volume fraction in oils means a greater number of sensitive particles and a larger spool clamping force. For the particles of a similar size with the clearance between spool valves, when their volume concentration tops over the "sensitive concentration", namely 5%, the risk of spool clamping rises in a drastic manner. This study provides a theoretical reference and an empirical equation for the mechanism of spool clamping under the action of particles, as well as a definite quantitative indicator for the prediction and estimation of spool clamping which is of positive significance for the study of the predictive maintenance of hydraulic equipment. [ABSTRACT FROM AUTHOR]

The shaft hydropower plant (SHPP) is a novel hydraulic concept for low-head hydropower sites with several environmental and operational advantages over conventional layouts. However, the first two projects implementing this concept have shown comparatively high construction costs and project risks. Therefore, further optimization is required to increase economic attractiveness and enable broader market adoption. Initial model tests recommend a square-shaped shaft inlet with a three-sided approach flow for low-loss and fish-friendly inflow conditions. Yet, this design requires significant space for structural implementation and may be unsuitable for use with multiple shafts or as an extension of non-powered dams and weirs. This research paper presents the application of a computational fluid dynamics simulation setup to evaluate the hydraulic performance of various design configurations, especially alternative design layouts with a one-sided approach flow without further physical model tests. The simulation setup is calibrated against observations including head loss and velocity measurements from the physical model tests, and its satisfactory performance enables the analysis of alternative design layouts. This study aims to derive the most significant design parameters for achieving the desired hydraulic conditions at the intake. Increasing the flow depth before the intake and enlarging the inlet area have the most significant impact, while increasing the overflow of the front gate has the least significant effect. The chosen CFD application is deemed suitable for hydraulic design optimization and provides guidance on the key parameters to focus on for tailored site-specific design development. [ABSTRACT FROM AUTHOR]

The compatibility of seal materials with the working fluid is crucial for the flawless, energy-saving, environmentally sustainable, and safe operation of any technical system. This is especially true for hydraulic systems operating under high operating pressure. The problem of materials compatibility comes into play when either a new type of seal material or a new type of fluid comes into use. The paper discusses the research findings regarding material compatibility testing of new high-tech ionic hydraulic fluids with commonly used seal materials. Due to the completely different chemical composition of these new fluids compared to the classical mineral-based oil, for these fluids, there are no standardized testing procedures. In these cases, we can only lean on the Standards that apply to classical fluids, which can lead to incorrect results. In the forefront of the paper is the discrepancy between the results obtained by the standardized test, and the test under real operating conditions. FKM, an excellent material for seals, proved to be the most suitable in the case of using ionic hydraulic fluid, according to a standardized test. However, it failed in the comparison test under real operating conditions, as the cylinder leaked. NBR seals proved to be a better solution. [ABSTRACT FROM AUTHOR]

Oil-filled motors (OFMs) are widely used in deep-sea exploration and oil well extraction. During motor operation, the rotor stirs the oil in the air gap, causing viscous loss. Viscous loss affects the temperature distribution inside the motor. Accurately calculating the viscous loss and temperature rise in OFMs can provide a basis for optimizing the motor's structural design. Motor structural parameters, including the rotor's outer diameter, air gap, and slot opening, have a significant impact on viscous loss. The working conditions of OFMs, such as rotor speed and environmental temperature, also affect viscous loss. The viscosity of hydraulic oil is highly influenced by temperature, and changes in viscosity can lead to changes in viscous loss. These changes in viscous loss, in turn, alter the temperature distribution. Therefore, the coupling relationship between viscous loss and temperature must be considered. Additionally, when Taylor vortices occur in the fluid, the surface roughness of the rotor also has a significant influence on viscous loss. Currently, both domestic and international research on viscous loss and thermal analysis struggle to simultaneously consider the coupling of viscous loss and the temperature field, rotor surface roughness, and the effect of motor structure. This paper summarizes the methods used in recent years for studying viscous loss and thermal analysis, and puts forward some suggestions for future research on the coupling of the OFM temperature field and viscous loss. [ABSTRACT FROM AUTHOR]

This paper presents an experimental analysis of a high-response piezoelectric actuator system for the modular design of hydraulic digital fluid control units. It focuses on determining static and dynamic characteristics, forming the basis for developing a smart Industry 4.0 component that incorporates both actuator and sensor function. The design process examines the main challenges, advantages, disadvantages, and working principles to define parameters that impact the actuator's behaviour and performance. The new piezoelectric actuator system features three piezoelectric stack actuators in series, enabling simultaneous actuation and sensing by applying and measuring the electrical voltage at each piezo element. The experimental setup and test methodology are explained in detail, revealing that the new design, combined with an appropriate open-loop or closed-loop control method, offers superior actuator stroke control, high stroke resolution, and a high-dynamic step response. This paper proposes a concept of a smart piezo actuator system focused on I4.0 and an actuator administration shell, integrated with 5G and RFID technology, which will allow automatic plug-and-play functionality and efficient interconnection, communication, and data transfer between the hydraulic valve and the piezoelectric actuator system. [ABSTRACT FROM AUTHOR]

Stepped spillways are specialized hydraulic structures crafted to optimize the effective dissipation of hydraulic energy along stepped chutes. The central objective is to scrutinize and improve the mitigation of flow separation occurring from the ogee crest to the stepped chute, focusing on various profiles within the critical zone (CZ) to understand its flow behavior. The study evaluates the impact of CZ profile alterations on velocity distribution, revealing a reduction in velocity ranging from 10% to 18% for nappe flow and 7% to 15% for skimming flow, with a dissipation rate 5% higher than other tested profiles in the CZ. By combining physical experiments and numerical simulations, the research aims to understand the complex dynamics of CZ flow. A comparative analysis is conducted, comparing turbulence models (specifically RNG) against experimental data for velocity and dissipation rate, considering different numbers of steps (N=16, 22, 56, 60). Moreover, the research seeks to unravel the effects of introducing additional steps within the CZ on crucial hydraulic parameters. The results indicate a significant improvement in flow patterns, velocity fields, and energy dissipation for the modified profile, highlighting the practical applicability of the proposed approaches in effectively sizing the CZ. [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.)

In this article, a mathematical model is established to determine the working parameters of a hydraulic recoil mechanism, considering the characteristic parameters of the oil. The parameters considered in this study are oil compression and oil temperature. Parameters such as recoil braking force, recoil velocity, recoil length, and recoil time are calculated in the cases of incompressible oil, compressible oil, and different working temperatures of oil. Numerical calculations are applied to 85 mm anti-tank artillery. Calculation results show that oil compression mainly affects the early stages of the recoil movement of the recoil part. When considering the oil’s compressibility, the maximum recoil brake force and maximum hydraulic brake force values are 73406 N, and 61052 N, respectively - reduced by 4.3% and 5.2% compared to the case of uncompressed oil. In addition, the working temperature of the oil also significantly affects the working parameters of the hydraulic recoil mechanism. The calculation results are a reliable theoretical basis for choosing oils suitable for the harsh working conditions of the hydraulic recoil mechanism during maintenance. [ABSTRACT FROM AUTHOR]

This study employs a rigorous methodology to assess the condition of the hydraulic oil in a recently introduced mini skid-steer loader. The assessment is conducted through laboratory analysis, which adheres to a range of international standards. The objective is to provide accurate insights into the viscosity, particle count, and characterisation of the oil, along with thermographic data. The friction of oil is evaluated at specific time points: 0, 10, 100, 125, and 150 h of operation. This examination offers a comprehensive insight into the alterations in oil characteristics during a pivotal period when machine components are undergoing initial consolidation and abrasion to attain the factory-defined performance thresholds. The principal aim of this research is to provide valuable insights into the wear of oil and hydraulic system components through an in-depth analysis of a range of variables. Moreover, the investigation aims to ascertain the impact of this factor on the temperature elevation of system components and accessories to formulate enhanced technical guidelines for implementation. The main results indicate the presence of particles in the oil, resulting in a cleanliness code of 23/21/13, which exceeds the permissible threshold of 20/18/15 specified in ISO 11171. In addition, hydraulic oil shows a viscosity instability of more than 10% due to moisture absorption, leading to wear of mechanical components composed of iron, nickel, copper, zinc, and silicon. This deterioration is corroborated by thermographic evaluations, which reveal a considerable temperature increase in components such as cylinders and system accessories. [ABSTRACT FROM AUTHOR]

With the increasing demand for heat dissipation of engineering vehicles, a dual-cycle cooling system is introduced in this paper to prevent the adverse effects of engineering vehicles' equipment when operating at the overheating temperature. The performance of the new system is analyzed through tests, and the results show that the dual-cycle cooling system can meet the thermal balance requirements of the engineering vehicle during the shovel operation. Compared with the traditional cooling system, the new cooling system improved performance in terms of volume, engine energy consumption and working oil efficiency. The oil consumption of a wheel loader using the dual-cycle cooling system is reduced by 1% per hour, and the temperature of its transmission oil and hydraulic oil is reduced by more than 10 °C. The new cooling system has bright future in energy saving and emission reduction of engineering vehicles. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF)/polyetherketoneketone (PEKK) composites are exposed to Skydrol, a hydraulic fluid made of phosphate esters widely used in the aviation field. The present study investigates Skydrol absorption of CF/PEKK composite layups and the associated PEKK matrix. A significant unexpected increase of Skydrol uptake is observed for cross‐ply composites (0.50%) compared to unidirectional ones (0.06%), independently of ply number. The use of 'model' fluids like water and ethanol allows to identify the origin of this anomalous Skydrol absorption in the case of cross‐ply layup. We propose that the latter involves an imbibition process governed by the fluid surface tension and the presence of submicronic cavities. SEM imaging of composite cross‐section after ion beam polishing confirms fiber‐matrix submicronic debonding in the interlaminar region in the cross‐ply composite. SEM–EDX confirms the presence of Skydrol into the submicronic cavities. Despite this anomalous absorption, off‐axis tensile testing as well as ILSS testing show no significant impact of Skydrol on CF/PEKK mechanical properties with less than 10% difference compared to the initial values. Highlights: Absorption by diffusion of Skydrol in neat PEKK and CF/PEKK compositesLink between fluid surface tension and anomalous Skydrol absorptionEvidence of submicronic cavities in CF/PEKK composites by means of SEM–EDXLow impact of Skydrol on CF/PEKK mechanical properties [ABSTRACT FROM AUTHOR]

AbstractOrganophosphorus compounds (OPs) are a diverse group of chemical compounds that contain organic moieties directly bonded to phosphorus or through a heteroatom like oxygen, nitrogen, or sulfur. They are ubiquitous in the human environment due to their unique properties and high biological activity. OPs have been widely used in various fields such as agriculture (as pesticides), industry (for producing lubricants, hydraulic fluids, and plastics), medicine (as drugs against osteoporosis, anticancer, and antiviral compounds), and veterinary (as anthelmintics). As an important class of organophosphorus compounds, this review provides an overview of phosphoramidate compounds covering their synthetic pathways, a brief explanation of their mechanisms, and their various applications. [ABSTRACT FROM AUTHOR]

As part of the research carried out in the field of processing systems and the production process of oil-hydraulic cylinders of large dimensions and power, the specifics of fluid power transmission, in the functioning of hydropower facilities, were analyzed. The research also includes the optimization of the physical–mathematical model of non-stationary processes, which take place inside the chamber of a large hydrocylinder. In parallel with the definition of the optimization model, the work parameters that affect the process of fluid flow and piston movement were determined. The operating and technological construction parameters of the hydraulic cylinder, which most significantly affect the operation of the hydraulic cylinder, were defined, and the observed parameters were optimized, based on which a prototype with improved characteristics compared to existing solutions was realized. [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.)

Exposure assessments to metalworking fluids (MWF) is difficult considering the complex nature of MWF. This study describes a comprehensive exposure assessment to straight and water-based MWFs among workers from 20 workshops. Metal and organic carbon (OC) content in new and used MWF were determined. Full-shift air samples of inhalable particulate and gaseous fraction were collected and analysed gravimetrically and for metals, OC, and aldehydes. Exposure determinants were ascertained through observations and interviews with workers. Determinants associated with personal inhalable particulate and gaseous fractions were systematically identified using mixed models. Similar inhalable particle exposure was observed for straight and water-based MWFs (64–386 µg/m3). The gaseous fraction was the most important contributor to the total mass fraction for both straight (322–2362 µg/m3) and water-based MWFs (101–699 µg/m3). The aerosolized particles exhibited low metal content irrespective of the MWF type; however, notable concentrations were observed in the sumps potentially reaching hazardous concentrations. Job activity clusters were important determinants for both exposure to particulate and gaseous fractions from straight MWF. Current machine enclosures remain an efficient determinant to reduce particulate MWF but were inefficient for the gaseous fraction. Properly managed water-based MWF meaning no recycling and no contamination from hydraulic fluids minimizes gaseous exposure. Workshop temperature also influenced the mass fractions. These findings suggest that exposures may be improved with control measures that reduce the gaseous fraction and proper management of MWF. [ABSTRACT FROM AUTHOR]

In seal applications a solid elastic body (the seal) ensures the separation of a liquid (e.g., hydraulic oil in one chamber) from a gas (e.g., air in another chamber). In the case of a dynamic seal, the rod is moving and transports a thin liquid film from the liquid chamber into the air chamber. The seal gap consists of a converging gap, a minimum distance between seal and rod and a diverging gap, where transported liquid detaches from the seal. Between the three states of matter (gas, liquid, gas) appear the following contact conditions: liquid‐to‐solid, gas‐to‐liquid, and gas‐to‐solid. A classical fluid‐structure‐interaction is technically possible with limited effort, but is not sufficient to distinguish between the liquid and the gas. A solution can make use of the fact, that the liquid has significant dimensions only in the liquid chamber and is pressurized only there. There is a thin liquid film on the rod in the air chamber, but it has dimensions clearly lower than the air chamber and has the same pressure as the air. Therefore a simulation is possible with the "variable viscosity approach": Liquid and gas are modeled in one single fluid domain. Differences between liquid and gas are included by pressure‐dependent fluid parameters, especially viscosity and density. The resulting violation of the mass balance is very small as the low mass flow through the seal lip is low. The presented approach allows to apply a fluid‐structure simulation with special fluid properties to model a system with three states of matter. Advantages are a less complex model with less complex contact conditions and a reduced simulation time. [ABSTRACT FROM AUTHOR]

The hydraulic leveling system plays an important role in the crane load-bearing platform (Referred to as CBP). In recent years, a lot of work has been done to improve the performance of the leveling system. However, all these efforts are focused on control techniques and methods, while ignoring other comprehensive improvement options. This article takes the hydraulic legs subjected to the synchronous drive system of CBP (Referred to as CBP) as the research object, a set of hydraulic synchronous leveling system used for the valve-controlled cylinder was designed, and the mathematical model of transfer function for the valve-controlled cylinder and the theoretical solutions of main parameters in hydraulic oil circuit are obtained, then establish a mechanical model suitable for the attitude position of CBP. After that, a composite leveling strategy applied to the fuzzy PID (Proportional Integral Differential) synchronous leveling system with hydraulic legs driven synchronously was proposed, and a fuzzy PID controller was mapped out independently. Meanwhile, the above-designed sync-drive system coupling synchronous leveling process suitable for the CBP legs was carried out by AMESim and MATLAB/Simulink software. In addition, the correctness and robustness of the simulation model were verified by the leveling experiment, and the validity and reliability of the previously designed oil circuit scheme was proved. The results proposed in this paper improve the hydraulic leveling accuracy and response speed to optimize the performance of the hydraulic leveling system. [ABSTRACT FROM AUTHOR]

Fossil fuel companies hold enormous political, economic, and knowledge production power. Recently, industry operators have pivoted from pushing climate denialism to campaigns aimed at individualizing responsibility for climate crisis. In this paper, we focus on one related outcome of such efforts – people's experiences of complicity – here in the context of unconventional oil and gas (UOG) production. We ask: How do mobilized activists experience fossil fuel scapegoating, and what does it mean for their goals as they organize against UOG production? We show that even activists fighting UOG production feel complicit in fossil fuel production, and these feelings of complicity diminish their demands for UOG accountability. We argue that these outcomes have been especially pernicious in cultural contexts like that of the United States, where neoliberal ideologies are normalized, centering personal responsibility, individualization, and identification as consumers rather than citizens. We marshal an extensive qualitative dataset and advance a theory of complicity as a way to understand: a) how social movements intersect with neoliberalized patterns of life; b) how experiences of complicity affect activism; and c) how this may contribute to fossil fuel firms' goals of undercutting organizing. We end by examining how a sub-set of activists works to dismantle this complicity narrative. [ABSTRACT FROM AUTHOR]

To understand the fluid hydraulic behavior change in a fracture under different shear displacements, fluid flow simulations at different flow velocities are carried out based on the Navier–Stokes equation. We characterized and conducted statistics on the change and distribution of the fracture aperture under different shear displacements, especially the measurement of the contact area under shear displacement, which was helpful for accurately studying the effect of shear displacement on fracture fluid flow. The results showed that the shear displacement of a fracture could be regarded as dislocation between the upper and lower fracture surfaces. The fluid flow velocity became larger near the contact sites and the streamlines became denser. The resulting hydraulic aperture exhibited a negative correlation with the contact area. The relationship between the volumetric flow rate and pressure gradient during the flow field simulation could be well-fitted by the Forchheimer equation, and the steepness of the curves was related to the contact area. The linear coefficient a and the nonlinear coefficient b in the Forchheimer equation were positively correlated with the contact area. Based on the measured flow velocity, the mechanical aperture was usually an order of magnitude larger than the hydraulic aperture. The linear relationship between the mechanical aperture and hydraulic aperture was described. The positive correlation between the permeability and mechanical aperture profiled during shear explained the hydraulic behavior in the flow field. [ABSTRACT FROM AUTHOR]

During the hydraulic fracturing process of coalbed methane (CBM) reservoirs, significant amounts of secondary coal fines are generated due to proppant grinding and crack propagation, which migrate with the fracturing fluid into surrounding fracture systems. To investigate whether coal fines can form plugs to reduce fluid leak-off during the hydraulic fracturing stage, we conducted physical simulation experiments on coal seam plugging and unplugging to demonstrate that coal fines indeed contribute to reducing fluid leak-off during hydraulic fracturing. We also explored the plugging mechanisms of coal fines under different concentrations and particle sizes in fracturing fluids, and revealed the damage law of coal fines of temporary plugging on reservoir permeability. Research results indicate the leak-off volume of fracturing fluids containing coal fines is lower than an order without coal fines, demonstrating a significant effect of coal fines in decreasing fluid leak-off. The temporary plugging rate of coal fines increases with higher concentrations and decreases with larger particle sizes, achieving rates exceeding 90%. The high temporary plugging effect of coal fines results from the superposition of internal and external filter cakes. Under conditions of small particle size and high concentration, the damage to fractures during the fine return process is minimized. Considering the potential damage of coal fines to propping fractures and wellbore, the concentration of coal fines in fracturing fluids should be kept relatively low while ensuring a high temporary plugging effect. Overall, these findings provide crucial insights into optimizing the temporary plugging performance of coal fines during the hydraulic fracturing stage and controlling their behavior during the fracturing fluid flow-back stage, thereby enhancing reservoir fracturing effectiveness and improving CBM production rates. [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.)

2-Phenoxyethanol (PhE) is widely used as a preservative in consumer products such as cosmetics as well as at the workplace as a component of metal-working fluids and hydraulic fluids. Therefore, both industry workers and consumers may potentially be exposed to PhE. An analytical method for the quantification of PhE and three selected metabolites, namely phenoxyacetic acid (PhAA), 4-hydroxyphenoxyacetic acid (4-OH-PhAA), and 4-hydroxyphenoxyethanol (4-OH-PhE), in human urine and blood was developed and validated. The sample preparation includes enzymatic hydrolysis of urine samples or protein precipitation of blood samples, followed by liquid – liquid extraction and silylation of the target analytes. Analyses of the extracts were carried out by gas chromatography with tandem mass spectrometry (GC – MS-MS). 3,4-Hydroxyphenoxyethanol, a probably minor PhE metabolite, could not be reliably analyzed due to its instability. The limits of quantification (LOQ) of the analytes ranged between 0.5 and 6.1 μg/L and 2.0 and 3.9 μg/L in urine and blood, respectively. The method was successfully applied to spot urine samples of 50 individuals without occupational exposure to PhE and additionally to blood samples from seven volunteers. In urine, PhAA and 4-OH-PhAA could be quantified in all analyzed samples, whereas 4-OH-PhE and unchanged PhE were found in 36% and 32% of the samples, respectively. In blood, PhAA was also found in every sample in levels above the LOQ, whereas PhE itself was detected in three of seven samples only. Neither 4-OH-PhAA nor 4-OH-PhE was found in any of the analyzed blood samples. The developed method promises to be a valuable tool for PhE monitoring of urine and blood samples and may also enable an advanced investigation of PhE biotransformation pathways in humans. [ABSTRACT FROM AUTHOR]

In order to solve the problem of unstable fluid supply pressure and serious impact caused by the complicated and changeable working condition of a fully mechanized mining face in coal mines and the sluggish response of the fluid supply system to the fluid demand for the hydraulic support, a control method based on online updating generalized regression neural network (GRNN) was proposed. Firstly, the simulated hydraulic support test platform and co-simulation model were built. Secondly, The optimal flow dataset of steady-pressure fluid supply under different working conditions is calculated by simulation. Furthermore, the GRNN prediction model was established by using dataset and online updating learning technology to predict the optimal fluid supply flow according to environmental parameters. Finally, the optimal flow control method of online updating GRNN was established, and numerical research and experimental verification were also carried out in different working conditions. The results indicated that the proposed control method could track the working conditions of the working face in real time and adjusted the fluid supply flow of the emulsion pump station adaptively, which effectively alleviated the pressure fluctuation and pressure shock, and the system pressure was more stable, meeting the demand of steady-pressure fluid supply on the working face. [ABSTRACT FROM AUTHOR]

In light of the heavy load applied by traditional air spring test equipment and its complex structural system design, a lever-type torque loading air spring test system is designed. It adopts the principle of Chinese scales to apply the load on the air spring in the form of proportional amplification, which can apply a simulated load on the air spring of 500–800 kg, using the vertical sliding shaft as the transverse limit to make the air spring elongate and compress by 280 mm in the longitudinal direction. The measurement and control system of the test equipment is then developed based on the LabVIEW platform, and the required sensors are selected and installed. The system can achieve real-time data acquisition of the air pressure, load, height and other parameters of the air spring and air spring charging and discharging control. Following the debugging of the function of the test equipment, the function of each subsystem is normal and able to meet the requirements of air spring characteristic and pressure tightness tests. For small spaces, such as laboratories, by reducing the installation of hydraulic and other oil source systems, avoiding the use of large mass blocks to simulate the loading of air spring loads and optimizing the complex installation and debugging process, this miniaturized design for air spring test equipment has benefits for practical applications. [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.)

Aircraft failures can result in the leakage of fuel, hydraulic oil, or other lubricants onto the runway during landing or taxiing. Damage to fuel tanks or oil lines during hard landings or accidents can also contribute to these spills. Further, improper maintenance or operational errors may leave oil traces on the runway before take-off or after landing. Identifying oil spills in airport runway videos is crucial to flight safety and accident investigation. Advanced image processing techniques can overcome the limitations of conventional RGB-based detection, which struggles to differentiate between oil spills and sewage due to similar coloration; given that oil and sewage have distinct spectral absorption patterns, precise detection can be performed based on multispectral images. In this study, we developed a method for spectrally enhancing RGB images of oil spills on airport runways to generate HSI images, facilitating oil spill detection in conventional RGB imagery. To this end, we employed the MST++ spectral reconstruction network model to effectively reconstruct RGB images into multispectral images, yielding improved accuracy in oil detection compared with other models. Additionally, we utilized the Fast R-CNN oil spill detection model, resulting in a 5% increase in Intersection over Union (IOU) for HSI images. Moreover, compared with RGB images, this approach significantly enhanced detection accuracy and completeness by 25.3% and 26.5%, respectively. These findings clearly demonstrate the superior precision and accuracy of HSI images based on spectral reconstruction in oil spill detection compared with traditional RGB images. With the spectral reconstruction technique, we can effectively make use of the spectral information inherent in oil spills, thereby enhancing detection accuracy. Future research could delve deeper into optimization techniques and conduct extensive validation in real airport environments. In conclusion, this spectral reconstruction-based technique for detecting oil spills on airport runways offers a novel and efficient approach that upholds both efficacy and accuracy. Its wide-scale implementation in airport operations holds great potential for improving aviation safety and environmental protection. [ABSTRACT FROM AUTHOR]

In the study of coronary artery disease (CAD), the mechanism of plaque formation and development is still an important subject for investigation. A limitation of current coronary angiography (CAG) is that it can only show static images of the narrowing of arterial channels without identifying the mechanism of the disease or predicting its progression or regression. To address this limitation, the CAG technique has been modified. The new approach emphasizes identifying and analyzing blood flow patterns, employing methodologies akin to those used by hydraulic engineers for fluid or gas movement through domestic or industrial pipes and pumps. With the new technique, various flow patterns and arterial phenomena—such as laminar, turbulent, antegrade, retrograde, and recirculating flow and potentially water hammer shock and vortex formation—are identified, recorded, and classified. These phenomena are then correlated with the presence of lesions at different locations within the coronary vasculature. The formation and growth of these lesions are explained from the perspective of fluid mechanics. As the pathophysiology of CAD and other cardiovascular conditions becomes clearer, new medical, surgical, and interventional treatments could be developed to reverse abnormal coronary flow dynamics and restore laminar flow, leading to improved clinical outcomes. [ABSTRACT FROM AUTHOR]

Although numerous experimental studies on a hybrid thruster have been recently executed, a fuel port pressure was rarely measured because a gap between a fuel and a fuel case is complicated to be sealed due to a fuel port pressure sensor hole. Therefore, the hybrid thruster with an exposed solid fuel was applied to install a fuel port pressure sensor without the fuel case. An exposed solid fuel hydrogen peroxide catalytic decomposition hybrid thruster with PE (PolyEthylene) and PMMA (PolyMethyl MethAcrylate) as fuels, H 2 O 2 as an oxidizer, MnO 2 /Al 2 O 3 as a catalyst for the oxidizer, 20 bar as a combustion chamber pressure, and 5 s as a burning time was organized. Combustion tests without fuel port pressure sensors to discern an effect of them and with PMMA to visualize a combustion were performed. A fuel port pressure distribution was satisfactorily measured. Three phenomena of four fuel port pressures and a post-combustion chamber pressure in a steady state included an increase at the beginning, a maintenance at the middle, and a decrease at the end induced by a variable oxidizer mass flow rate, a flame generation, and a fuel regression respectively. • Application of exposed solid fuel to install fuel port pressure sensor on fuel. • Combustion visualization to explain occasional error solved by hydraulic fluid. • Increase of fuel port pressure at beginning due to variable oxidizer mass flow rate. • Maintenance of fuel port pressure at middle due to flame generation. • Decrease of fuel port pressure at end due to fuel regression. [ABSTRACT FROM AUTHOR]

In this paper, dynamic modeling and simulation of a new hydraulic fluid flow control strategy which is inlet throttled pump is presented with the goal of studying the system efficiency and feasibility. In this system, a valve is used at the pump inlet to restrict the flow which reduces the power losses that exist with traditional valve control systems in which the valve is placed at the pump discharge. In addition, the proposed system uses a fixed displacement pump which has lower cost and simpler dynamics compared to displacement controlled pumps. The mathematical models created in this work include models for the volumetric and mechanical efficiencies of the system. Experiments have been performed to validate the mathematical models proposed in this work. The effects of the inlet pressure, supply pressure, pump angular speed, and valve opening area on the volumetric and mechanical efficiencies of the pump were investigated. The results demonstrated that the system has great volumetric efficiency which increases with the increase of the pump speed and decreases with the increase in the discharge pressure. The inlet pressure and the valve opening area were shown to have no significant impact on the volumetric efficiency. The mechanical efficiency of the system was shown to be proportional to the valve opening area, inlet and supply pressures and inversely proportional to the angular speed of the pump. It can be seen that excellent agreement between the theoretical and experimental results was achieved. The results of the present work reveals that the proposed system can be used as an excellent alternative of the available hydraulic fluid flow control strategies in terms of feasibility, efficiency, cost, and simplicity. [ABSTRACT FROM AUTHOR]

Magnetic vortex pumps are characterized by their high performance and zero leakage, and in recent years, they have been applied for the transportation of antifreeze coolant in varying-temperature environments. This paper combines Computational Fluid Dynamics (CFD) with experimental verification to study the external and internal flow characteristics of magnetic vortex pumps when transporting working fluid at different temperatures, considering radial clearance flow. The results indicate that as the temperature of the medium increases, both the pump head and efficiency improve. Specifically, under the design flow rate condition, the pump head increases by 16.7% when transporting a medium at 90 °C compared to ambient-temperature conditions. Conversely, the pump head is only 16.8% of that observed under ambient-temperature conditions when transporting a medium at −30 °C. Analysis of the internal flow field reveals that the changes in pump hydraulic performance at different working fluid temperatures are primarily due to variations in the vorticity of the internal flow field. [ABSTRACT FROM AUTHOR]

Some users consider modern hydrostatic drives and controls to be unreliable and difficult to maintain. This view is often due to operational problems caused by issues with obtaining and then maintaining the appropriate cleanliness class of the working fluid. Recommendations on the selection of appropriate filtration system elements can be found in the literature, but there is no numerical model that could be helpful in a detailed analysis of the phenomenon. In the article, the authors tried to fill the research gap regarding the lack of a filtration model based on the filtration efficiency coefficient of filter elements used in hydraulic drives and controls. The developed model allows users to determine the influence of selected filtration system parameters on the separation of contaminants by filter elements. The model is intended to help designers and users of hydraulic drives and controls in optimizing the filtration system in order to obtain and then maintain the required cleanliness class of the hydraulic fluid. This paper also includes the results of the sensitivity analysis of selected filtration-system operating parameters in terms of the highest efficiency. In order to verify the developed model, experimental tests were also carried out, with the results presented in this paper. Based on the numerical analyses and experimental studies, recommendations that may be helpful in the selection or development of filtration systems used in hydrostatic drives and controls were developed. [ABSTRACT FROM AUTHOR]

In light of the European Union's zero-emissions policy and the growing demand for energy associated with technological advances, it is necessary to consider adopting technologies and innovative solutions that simultaneously reduce greenhouse gas emissions while increasing potential extraction from existing hydrocarbon deposits, for example. This can result in increased production from deposits with low reservoir energy values or those in which the energy value does not allow the resource to be exploited on its own. By using a hydraulic drilling nozzle that harnesses the hydraulic energy of the fluid stream for workover, the possibility of increasing the contact between the reservoir layer and the producing well increases in direct proportion to the number of small-diameter radial wells drilled with a hydraulic rotary head from a horizontal well toward the reservoir layer. The main aspect of this paper is to outline an algorithm for the design of rotary drilling heads to maximize the use of the hydraulic energy from fluid streams flowing from the face of innovative drilling tools. The presented design algorithm allows changing the mutual position between the holes in the face section and the angle of the holes with respect to the longitudinal axis of the designed hydraulic rotary nozzle, simplifying the design work. The use of the rotary head developed using this algorithm enables seamless drilling in rocks with compressive strength Rc = 50 MPa, considering the drilling progress at ROP = 4 mm/s. [ABSTRACT FROM AUTHOR]

Fluidic actuation systems are optimizable as to energy consumption by reducing the friction in the hydraulic cylinders. Polymeric materials with special antifriction properties and good resistance to hydraulic fluids can be deployed to enhance the performance of hydraulic cylinders. Small friction forces can also be ensured by facilitating the hydrodynamic separation of the elements of the friction tribosystem, namely the seal and sealed-off surface, respectively. The study presented in this paper analyzed the hydrodynamic separation phenomenon in hydraulic cylinders with coaxial sealing systems of the pistons. The process underlying the forming of the fluid film between the seal and its contact surface was considered and the formula for calculating film thickness was deduced. This paper presents graphs that describe the variation of the fluid film thickness versus the dimensional and material characteristics of the sealing systems. The study yielded recommendations as to the most adequate polymeric material to be used and the optimum dimensional characteristics of the seal. [ABSTRACT FROM AUTHOR]

Clamping precision as a key factor of precision injection molding of high-quality plastic parts is restricted by low-precision clamping systems. Herein, a novel clamping method capable of sensing mold misalignment and self-adjusting mold position and attitude through floating structures is proposed to eliminate the restriction of clamping system, thereby achieving high clamping precision. The innovative clamping method possesses prestress steel wire-winding frames and rubber capsules filled with hydraulic oil, which ensures the floating structures work. Meanwhile, the hydraulic oil provides isostatic pressure to clamp the mold. The working space of the floating structures and the loading of the prestress steel wire-winding frames have been modeled to confirm their feasibility in the self-adaptive clamping method. Based on the modeling activities, a prototype injection molding machine was developed to evaluate the clamping precision. The experimental results indicate that the parallelism between the mold plates is 0.031 mm, far superior to that in China Machinery Industry Standards, and the uneven clamping force rate on mold cavity surface is 1.3 %. Moreover, the clamping force repeatability is only 0.14 %, superior to toggle and two-platen clamping systems. This method offers a new chance for the development of precision injection molding. • A novel clamping method capable of sensing mold misalignment and self-adjusting mold position and attitude. • The clamping method utilizes capsule with hydraulic oil to provide isostatic pressure and ensure floating structures work. • The prestress steel wire-winding frames in the clamping system cannot restrict degree of freedom of floating structures. • The developed clamping system is verified that the clamping precision is superior to traditional clamping systems. [ABSTRACT FROM AUTHOR]

At present, conventional smooth hydraulic fracturing fluid systems generally have various functions such as drag reduction, sand carrying, salt resistance, and temperature resistance, but none of them have considered achieving reservoir protection by changing the surface wettability of the reservoir. Therefore, in this paper, a superhydrophobic multifunctional fracturing fluid drag reducing agent, named SHJZ-1, was synthesized using acrylic acid, acrylamide, self-made material 2-acrylamido-2- phenylethanesulfonic acid, and hydrophobic modifier as raw materials. The structure of the synthesized drag reducing agent was characterized by infrared spectroscopy, and its performance was comprehensively evaluated through various methods such as hightemperature and high-pressure core dynamic damage evaluation system, contact angle measurement instrument, Hack rheometer, and closed pipeline friction tester. The results show that the drag reducing agent SHJZ-1 had a short dissolution time and rapid adhesion. When the salinity of saline water reaches 40000 mg/L, the drag reduction rate of 0.5% SHJZ-1 solution was about 68%. The 0.15% SHJZ-1 solution can still achieve a drag reduction rate of over 70% after high-temperature aging at 140 ℃. Furthermore, the core treated with 1.3% SHJZ-1 solution exhibited superhydrophobic effect, with a core contact angle of 151.21°. Additionally, the average permeability damage rate of the core caused by this drag reducing agent solution was only 11.6%. The super hydrophobic multifunctional smooth hydraulic fracturing fluid system has been successfully applied on site in the HX-1 well. In fracturing engineering, the performance of smooth hydraulic fracturing fluid is relatively stable, and the production after fracturing is increased by more than 10% compared to the adjacent well. The effect is significant, achieving the goal of improving quality and efficiency. [ABSTRACT FROM AUTHOR]

In hydraulic active suspension systems, an oftenoverlooked source of nonlinearity is the performance deviation of the working hydraulic oil through the wide band of operating temperatures. In this paper, a quarter-car, Simulink® Simscape nonlinear hydraulic active suspension model has been constructed, taking ISO VG 22 oil as the working oil[1]. A PID controller has been tuned for the active suspension system. Targeted response parameters were tire deflection and suspension travel, as measures of vehicle handling, and sprung-mass acceleration as a measure of riding comfort. At a typical moderate vehicle speed of 40 km/hr, system response was investigated for both single sinusoidal bump and continuous wavy sinusoidal road inputs. Simulation was performed at two distant, extreme, operating temperatures, namely 60°C and -30°C. Results showed that at higher temperatures, the decrease in oil viscosity of the hydraulic actuator results in higher tire-rebound amplitudes and longer settling times, and a higher sprung mass acceleration amplitude, worsening both tire-road holding, and ride comfort compared to those at -30°C. The most significant conclusion is that an active suspension’s hydraulic actuator actually behaves as a nonlinear damper, besides being a force generator. [ABSTRACT FROM AUTHOR]

The intrusion of micrometer-sensitive contaminant particles into the clearance of sliding valves within hydraulic fluids is one of the root causes of valve sticking and reliability issues in hydraulic systems. To reveal the transient process and characteristics of particle intrusion into the clearance process, this paper proposes a numerical method for fluid–particle one-way coupling and verifies it through experimentation. Furthermore, a numerical simulation of the motion trajectory of spherical iron particles inside the valve chamber was conducted in a two-dimensional flow model. It was discovered that in a steady-state flow field with a certain valve opening, micrometer-sized particles in the valve chamber's hydraulic fluid mainly move with the valve flow stream, and the number of micron particles invading the slide valve clearance and the probability of invasion is related to the slide valve opening and differential pressure. When the slide valve opening decreases, especially in the small opening state, the probability of particles invading the slide valve clearance will increase dramatically, and the probability of invading the clearance is as high as 27% in a valve opening of 50 μm; the larger the pressure difference between the valve ports, the more the number of particles invading the slide valve clearance increases; the particles in the inlet of the slide valve clearance are more prone to invade the slide valve clearance, and invade in an inclined way, touching the wall and then bouncing back. These findings are of great value for the design of highly reliable hydraulic control valves and the understanding of the mechanism of slide valve stalls and provide an important scientific basis for the optimization and improvement in the reliability of hydraulic systems. [ABSTRACT FROM AUTHOR]

In mining machines with friction discs, but also in multi-rope traction elevators, it is necessary to distribute the applied tensile load, generated by the weight of the cage and counterweight, evenly in all cross-sections of the load-bearing ropes. Hydraulic devices used for this purpose can operate on the principle of Pascal's law. This article presents a structural design, a 3D model and an implemented solution of a laboratory device capable of simulating a practical method of evenly distributing the total weight of the load into partial tensile forces of the same size acting on a selected number of load-bearing ropes. The laboratory equipment uses two pairs of three steel cables of finite length for the simulations. During the experimental measurements, tensile forces derived from the tractive force of the piston rods, pushed into the bodies of the hydraulic cylinders by the pressure of the hydraulic oil supplied through the pipeline under the pistons of the hydraulic cylinders, were detected. The resulting amount of hydraulic oil pressure in the hydraulic circuit influenced by different values of the hydraulic oil pressures in the hydraulic cylinders and by the pressure in the supply pipe was experimentally studied on the laboratory equipment. Simulations were also carried out in order to detect the hydraulic oil pressure in the hydraulic circuit caused by the change in the different magnitudes of the tensile forces in the ropes. From the experiments carried out, it follows that with the appropriate choice of hydraulic elements and the design of the hydraulic circuit, the weight of the load, acting as the total pulling force in the ropes, can be evenly distributed (with a deviation of up to 5%) to all cross-sections of the load-bearing ropes. If the exact values of the hydraulic oil volumes under the pistons of all hydraulic cylinders are not known, it is not possible to calculate the pressure values in the hydraulic circuit when the valves of the hydraulic pipes are gradually opened. [ABSTRACT FROM AUTHOR]

Large pulsation and impact occur during the working process of hydraulic rock drill, which has a negative influence on the system. Aiming at this phenomenon, the related characteristics of hydraulic fluid inertia are studied in this paper. The dynamic model of impact and reversing mechanism of rock drill is established. Through the parameter analysis of the model, the concepts of hard parameter quantity and soft parameter quantity are proposed. The influence coefficient C of the initial section of crevice flow including the influence of fluid inertia is deduced, and the comprehensive factors such as hydraulic oil velocity, unstable flow and friction resistance are analyzed, The value of soft parameter quantity ζ is (ξ+1) ~ (ξ+ 1.5)。The pressure test of the working chamber is designed and 7 groups of data are obtained. Through data analysis, the influence of C on the simulation results is obtained, which has a great influence on the reversing valve. The deviation of simulation data of left and right valve chamber pressure is increased from ± 8% to ± 3%. It has a certain impact on the impact piston. The deviation of simulation data increases from ± 5% to ± 3%, and has little impact on the accumulator. The deviation of simulation data increases from ± 4% to ± 3%. [ABSTRACT FROM AUTHOR]

The efficiency of quarry hydraulic excavators will depend on several factors, namely the climatic conditions of the area where hydraulic excavators are used, the degree of air pollution (pollination), the performance of the structural parts of the excavator, the reliability of the hydraulic system, the performance and cleanliness of the hydraulic working fluid. In this area, research was carried out on the performance of seals used in the hydraulic system of quarry excavators. The article presents the results of experimental tests of the existing type of oil seal a and b, as well as the proposed oil seal type c, shown in Fig. 1. [ABSTRACT FROM AUTHOR]

The use of thermoplastic elastomers (TPE) in 3D printing technology enables the use of this technology to produce prototype seals with an unusual shape or design solution. Tribological tests were carried out on a pin-on-disc test stand. The influence of contact pressure and sliding velocity on the friction coefficient of the TPE-steel friction pair under mixed lubrication conditions was analyzed. Based on the obtained tribological test results, it was found that the coefficient of friction of the thermoplastic TPE elastomer on steel in the presence of hydraulic oil (mixed lubrication) at a sliding velocity below 1 m/s does not exceed μ = 0.25. The obtained friction coefficient values are comparable to the results for other elastomeric materials used for technical seals. It was found that the influence of contact pressure on the value of the friction coefficient in the tested friction pairs is varied and depends, for example, on the sliding velocity. It was recommended to carry out research on the assessment of durability (wear intensity) and structure (porosity) of the material in elements manufactured using 3D printing to obtain full knowledge of the possibility of using these materials in the area of technical aircraft seals. [ABSTRACT FROM AUTHOR]