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An electro-hydraulic system is a control system that combines electrical and hydraulic power to operate machinery and equipment. In this type of system, electrical signals are used in place of mechanical force to regulate the flow of hydraulic fluid, enabling functions such as movement, lifting, turning, and holding in industrial machines. Increasingly, excavators and wheel loaders are adopting electro-hydraulic systems rather than hydro-mechanical systems in order to achieve greater control accuracy and improved operational efficiency. This study examines several common hydraulic control methods used in excavators, including Negative Flow Control (NFC), Positive Flow Control (PFC), Load-Sensing Control (LSC), and Power-Limitation Control (PLC). In addition, linearized multiple-input, multiple-output models of variable-displacement piston pumps and working loads are developed and analyzed with respect to stability and controllability. The control input signals are further investigated and designed according to the objectives and characteristics of NFC, PFC, and LSC systems. Furthermore, an integrated electronic control algorithm is proposed, incorporating electronic sensor feedback to enable the machine to apply and switch among NFC, PFC, and LSC either manually or automatically. Power-Limitation Control (PLC) is also implemented through swashplate angle feedback to prevent the machine’s prime mover from stalling. The integrated control system provides the flexibility to optimize machine efficiency and performance under varying working conditions, while also accommodating different operator preferences. This work is novel in that it unifies multiple conventional pump control methods into one integrated electro-hydraulic control platform. Its practical impact lies in enabling a single excavator system to achieve better adaptability, improved operating efficiency, and more flexible control under varied task demands. Such a capability is especially valuable for modern construction equipment, where intelligent control, reduced energy consumption, and higher productivity are increasingly important.

The complex flow state of the fluid makes it difficult for the pump valve to accurately control it. A study was conducted on the pressure flow control of a valve control device for gas-liquid two-phase flow, and experiments were conducted on the joint control of gas-liquid two-phase flow. The results showed that pressure has a significant impact on control, and it is necessary to ensure that pressure remains constant during the control process. The joint control of gas-liquid two-phase flow has consistency in changes, and precise control of gas-liquid two-phase flow can be achieved through studying consistency.

Power flow control has become increasingly important in recent years in the area of smart power systems that have to integrate increased shares of variable renewable energy sources. The unified power flow controller (UPFC) provides in real-time, simultaneously or selectively, active and reactive power flow control as well as voltage control in smart power systems. Several models and methods have been suggested for the control, analysis, operation, and planning of UPFCs in smart power systems. This study introduces a review of the state-of-the-art models and methods of UPFCs in smart power systems, analysing and classifying current and future research trends in this field.

The Energy System Transition in Aviation research project of the Aeronautics Research Center Niedersachsen (NFL) searches for potentially game-changing technologies to reduce the carbon footprint of aviation by promoting and enabling new propulsion and drag reduction technologies. The greatest potential for aerodynamic drag reduction is seen in laminar flow control by boundary layer suction. While most of the research so far has been on partial laminarization by application of Natural Laminar Flow (NLF) and Hybrid Laminar Flow Control (HLFC) to wings, complete laminarization of wings, tails and fuselages promises much higher gains. The potential drag reduction and suction requirements, including the necessary compressor power, are calculated on component level using a flow solver with viscid/inviscid coupling and a 3D Reynolds-Averaged Navier-Stokes (RANS) solver. The effect on total aircraft drag is estimated for a state-of-the-art mid-range aircraft configuration using preliminary aircraft design methods, showing that total cruise drag can be halved compared to today’s turbulent aircraft.

Organ-on-a-chip (OoC) devices require the precise control of various media. This is mostly done using several fluid control components, which are much larger than the typical OoC device and connected through fluidic tubing, i.e., the fluidic system is not integrated, which inhibits the system’s portability. Here, we explore the limits of fluidic system integration using off-the-shelf fluidic control components. A flow control configuration is proposed that uses a vacuum to generate a fluctuation-free flow and minimizes the number of components used in the system. 3D printing is used to fabricate a custom-designed platform box for mounting the chosen smallest footprint components. It provides flexibility in arranging the various components to create experiment-specific systems. A demonstrator system is realized for lung-on-a-chip experiments. The 3D-printed platform box is 290 mm long, 240 mm wide and 37 mm tall. After integrating all the components, it weighs 4.8 kg. The system comprises of a switch valve, flow and pressure controllers, and a vacuum pump to control the diverse media flows. The system generates liquid flow rates ranging from 1.5 μLmin-1 to 68 μLmin-1 in the cell chambers, and a cyclic vacuum of 280 mbar below atmospheric pressure with 0.5 Hz frequency in the side channels to induce mechanical strain on the cells-substrate. The components are modular for easy exchange. The battery operated platform box can be mounted on either upright or inverted microscopes and fits in a standard incubator. Overall, it is shown that a compact integrated and portable fluidic system for OoC experiments can be constructed using off-the-shelf components. For further down-scaling, the fluidic control components, like the pump, switch valves, and flow controllers, require significant miniaturization while having a wide flow rate range with high resolution.

The flow-matching problem of hydraulic systems is an important factor affecting the working performance and energy saving of hydraulic systems. According to the different flow-matching mechanisms, the flow-matching technology of hydraulic systems can be divided into three categories: positive flow-control technology, negative flow-control technology, and load-sensitive control technology. In this paper, the working mechanism of flow-matching technology and the cause of energy loss are analyzed, and the research results of flow matching are introduced from two aspects of energy saving and consumption reduction and system performance improvement. In the direction of energy saving and consumption reduction, the purposes of energy saving and consumption reduction are achieved by means of multi-way valve commutation, independent inlet and outlet control, parallel replacement of shuttle valve by a cylinder piston rod controlled by pilot pressure, change of hydraulic resistance of a pressure compensating valve, improvement of the power regulation range of a hydraulic pump, and potential energy recovery. In the direction of system performance, by means of flow-forecasting system pressure change, applying flow unsaturation real-time control idea, and combining electronic control technology with load-sensitive technology, the pressure drop during transmission process and the transmission signal lag are reduced, the speed regulation interval is enlarged, fine-tuning characteristics are improved, and the response speed is increased. The research results indicate that improving the structure and the control strategy of hydraulic systems and improving the flow-matching degree of a system to achieve global matching will be a future development trend.

Introducing a slot into an airfoil is a passive flow control technique that enhances aerodynamic performance by manipulating the boundary layers of fluid flow. This study investigates the aerodynamic performance of a novel double-split slot design using the NACA 0018 airfoil through a detailed 2D steady-state numerical analysis. A parametric study was conducted to evaluate the influence of key design parameters, including slot outlet location, outlet width, and wedge element length, on the force coefficients and the flow structure around the airfoil. Results demonstrate that the double-split slot effectively weakened the flow separation on the suction side, at moderate to higher angles of attack (15° ≤ α ≤ 30°). The optimal slot configuration achieved a lift coefficient ( C L ) improvement of 118% and a drag coefficient ( C D ) reduction of 49% compared to the baseline clean airfoil. Slot configurations with outlets positioned closer to the leading edge (LE), wider outlet widths, and longer split channels displayed improved performance by preventing flow detachment. Most double-split slots delayed flow separation by up to 10° in AOA. Overall, slotted airfoils demonstrated superior performance over clean airfoils at higher AOAs, making them particularly beneficial for vertical-axis wind turbine blade applications.

The goal of reducing aerodynamic drag is crucial for improving vehicle fuel efficiency and lowering emissions, particularly in bluff-body vehicles undergoing significant wake-induced drag. This research explores the aerodynamic characteristics of a modified Ahmed body model through computational fluid dynamics (CFD) simulations conducted in ANSYS Fluent. The main objective is to assess the impact of passive flow control by embedding a vortex generator at the rear of the vehicle, with inclination angles ranging from 0° to 30°. The baseline model shows considerable wake formation due to early flow separation, leading to a high drag coefficient of 0.864 and a notably negative rear pressure coefficient of -0.306. Implementing the vortex generator effectively delays separation, reduces the wake size, and enhances rear pressure recovery. The best aerodynamic performance is observed at a vortex generator inclination angle of 20°, where the drag coefficient decreases by 8.68% and the average rear pressure coefficient improves to -0.1936. Beyond 20°, the effectiveness declines due to increased flow disturbances and turbulence, causing a rise in drag. These results confirm the angle-dependent behavior of vortex generators and their potential for passive drag reduction, aligning with existing literature. The findings provide valuable insights for optimizing the aerodynamics of ground vehicles using cost-effective, energy-efficient flow control methods.

This article provides a comprehensive review of key approaches to suppressing stall flow in pumps, offering insights to enhance pump performance and reliability. It begins by outlining the formation mechanisms and characteristics of stalls, followed by an in-depth analysis of various stall types. The discussion highlights passive and active flow control methods, emphasizing their roles in suppressing stall phenomena. Passive flow-control strategies, including surface roughness, grooves, obstacles, fixed guide vanes, and vortex generators, are examined with a focus on their mechanisms and effectiveness in suppressing stall. Similarly, active flow-control techniques, such as jets and adjustable guide vanes, are explored for their capacity to regulate the flow field and suppress stall. The novelty of this review lies in its exploration of the effectiveness of passive and active flow-control methods in suppressing pump stall, with a focus on their mechanisms of action and the underlying principles of stall formation. The findings reveal that appropriate flow-control measures can mitigate laminar flow separation and reduce performance losses associated with stall. However, careful attention must be given to the optimal arrangement of control devices. Finally, the article highlights the limitations of current implementations of combined active and passive flow-control methods while offering insights into the future potential of advanced flow-control technologies in regard to suppressing stall.

In order to design high-strength downhole flow control valve, realize stratified oil and gas production and dynamic regulation, improve mining efficiency, reduce pollution and promote the development of intelligent completion technology, this paper selects processing materials suitable for electro-hydraulic composite intelligent completion flow control valve based on field working conditions and the working principle of hydraulic control flow control valve. The structure of key components such as valve body, slide sleeve and throttle valve sleeve is designed, and the mechanical properties of key components of flow control valve are modeled and simulated successively by numerical simulation method combined with the actual service conditions of flow control valve in the underground, and the service reliability of flow control valve is clarified. The results show that: Under the coupling conditions of pressure 50 MPa, load 650 KN and temperature 125 °C, the maximum stress value appears on the surface of the throttle valve sleeve is 980 MPa, and the maximum deformation of the parts is controlled within 0.202 mm, and the strength of all parts is lower than the yield strength of the material, fully meeting the requirements of the field working conditions. This tool is of great significance for improving oil field recovery and intelligent well completion development.