Pressure Control Method Research Articles

Method—Best Practices and Common Pitfalls in Experimental Investigation of Electrochemical CO2 Reduction at Gas Diffusion Electrodes

Gas diffusion electrodes (GDEs) play a crucial role in the development of electrochemical CO2 reduction (eCO2R) toward an economically viable process. While membrane electrode assemblies (MEAs) are currently the most efficient approach due to their low cell voltage, electrolyte supported GDEs still present a valuable tool for the characterization of catalysts under industrially relevant current densities, allowing for direct measurement of the electrode potential against reference electrodes. In this study, common experimental methods of iR correction and pressure control in eCO2R literature studies on GDEs are analyzed and compared regarding their potential impact on the reported results. It is revealed that failure to account for dynamic changes in iR-drop can lead to significant inaccuracies in reported electrode potentials. Additionally, common methods for the application of differential pressure across GDEs are shown to impact the performance, leading to additional errors in experimental results. Based on these findings, an experimental protocol for the application of single high frequency response as a method for iR correction is developed, providing a tool for reproducible electrochemical characterization of GDEs in eCO2R.

Many-body dissipative particle dynamics analysis: Generation and stability of bulk nanobubbles under the influence of pressure

Bulk nanobubbles can be generated through various methods such as ethanol-water exchange, vacuum method, and pressure method. However, the mechanisms and stability of nanobubble generation under pressure are unknown. In this study, a new pressure control method is proposed by combining the pressure control advantages of dissipative particle dynamics (DPD) with molecular dynamics (MD). The effectiveness and rationality of the new pressure control method are validated by using system temperature and pressure as indicators. Furthermore, based on the Ferralo experiment, the experimental process is decomposed and abstracted into specific simulation processes to investigate the effect of pressure on the stability of bulk nanobubbles. The results show that the pressure changes in the two-phase flow can be well controlled by the pressure plate and the pressure regulator based on DPD. A large amount of bulk nanobubble generation occurs during depressurization in a confined space, while pressurization leads to the dissolution of unstable bulk nanobubbles, while stable bulk nanobubbles persist.

Correction to: An Innovative Mechanism of Directional Rock Cracking Mechanics and Mine Pressure Control Method for Energy-Gathering Blasting

Correction to: An Innovative Mechanism of Directional Rock Cracking Mechanics and Mine Pressure Control Method for Energy-Gathering Blasting

Diamond-based HBAR as a high-pressure sensor

Features of an application of a High-overtone Bulk Acoustic Resonator (HBAR) as a high-pressure sensor have been considered. In this way, the second version of an integrated measurement system combining a Diamond Anvil Cell (DAC) and an HBAR operating in the microwave frequency band from 1.3 to 3.7 GHz was developed. A specific configuration of HBAR based on a piezoelectric layered structure as “Al/ASN/Mo/(100) diamond” was proposed. Two independent methods of pressure control were used to calibrate the embedded HBAR as a pressure sensor: a stress-induced shift of the diamond Raman line and the shift of the R1 luminescence line of Cr3+ in the ruby matrix. A stable correlation between the frequency shifts of the acoustic overtones in the HBAR, the shift of the diamond Raman line and the shift of the R1 line with a change in pressure applied to the W-gasket with embedded ruby particles was established in the range of 0 … 30 GPa. The sensitivity of an investigated sensor to the pressure variation was found to be equal 1ΔPΔff=4.8∙10-4GPa-1. The maximal value of 30 GPa obtained in a given work can be easily increased after a minor reconfiguration of the DAC. Considering the range of 0 − 5 GPa a proposed built-in DAC acoustoelectronic sensor has the better performance and sensitivity compared with known methods of a pressure measurement.

Low-loss nodeless hollow-core anti-resonant soft glass fiber for the 4 µm mid-infrared spectral range.

Infrared soft glass hollow-core anti-resonant fibers (HC-ARF) with low loss, excellent mode purity, and robust high-power transmission capabilities have vast potential in mid-infrared high-power laser transmission and biomedical fields. Despite this, the fabrication of these fibers still faces formidable challenges, coupled with an incomplete understanding of the transmission characteristics, thereby amplifying the value of further exploration. In this paper, we fabricate a six-cell nodeless infrared HC-ARF originating from purified sulfide glass, synthesized using a meticulous "stack-and-draw" method and dual-gas-path pressure control method. Notably, we experimentally validate the theoretical performance expectations of this fiber. The fiber exhibits outstanding transmission capabilities and optical transmission quality, characterized by a recorded loss of 0.56 dB/m at 4.79 µm. This is already comparable to traditional step-index sulfide fibers, fully demonstrating its tremendous research value and application potential. Our work has successfully fabricated the lowest loss anti-resonant fiber on record in the mid-infrared field, propelling the development of sulfide HC-ARFs into a new phase and laying a solid foundation for the realization of fiber applications in laser transmission and the biomedical field.

Optimization of Support and Relief Parameters for Deep-Buried Metal Mine Roadways

The management of rock mass deformation in high-stress roadways is a pivotal aspect of deep geotechnical engineering. Given the fruitful outcomes of research in rock mechanics regarding traditional confining pressure control methods, scholars have increasingly turned their attention to exploring pressure-relieving techniques, including borehole pressure relief and blasting pressure relief. However, there is limited research on pressure relief methods for deep-buried hard rock tunnels. This article commences with an overview of pressure relief in the roadway and conducts a detailed study on the parameters and methods of pressure relief in the roadway. To address safety and mining efficiency challenges, such as severe deformation leading to support failures, this study conducted a parameter analysis using the Sanshandao Gold Mine as a case study. Based on existing support methods, a strategy for arranging pressure relief roadways at varying distances from the main roadway is proposed, significantly enhancing the stress environment there. Numerical simulation software was employed to model two scenarios: (1) excavating the pressure relief roadway, main roadway, and maintenance roadway simultaneously and (2) first excavating the pressure relief roadway, followed by the main roadway and the maintenance roadway simultaneously. Simulation results indicated that the first pressure relief approach outperforms the second. The optimal position for both pressure relief roadways is 15 m from the main roadway, resulting in maximum deformation of the main roadway within 100 mm. These findings align with on-site stress monitoring data and satisfy safety production criteria. The research offers a theoretical foundation for similar pressure relief techniques in deeply buried, high-stress roadways.

A new method of mining pressure control for roof cutting in advance working face

After the extraction of deep coal resources, the original stress state is disrupted, leading to increased abutment stress ahead of the working face. This heightened pressure causes significant deformation in the roadway preceding the working face. To tackle this issue, a pioneering method called Roof Cutting in Advance of the Working Face(RCAWC) has been introduced to mitigate deformation by proactively alleviating pressure. This method leverages the principle of conservation of energy within the rock mass system, augmenting the fragmentation energy of the roof rock mass through controlled blasting. This process aims to release the accumulated energy within the rock mass, thereby reducing pressure. This research not only elucidates the mechanism employed by RCAWC to counteract mining pressure but also delineates the evolving pattern of bearing pressure at various RCAWC heights. The findings reveal a shift in the abutment stress curve from a single-peaked to a double-peaked pattern after roof cutting. Notably, there is a significant reduction in abutment stress as the RCAWC height increases. However, as the thick roof is cut off, the negative correlation effect diminishes. Subsequently, an engineering implementation was carried out. Following the adoption of RCAWC technology, roadway deformation decreased by 63.6 % to 75 %, and the size of the protective coal pillar reduced by approximately one-third. These findings underscore the remarkable effectiveness of RCAWC technology in impeding the propagation of mining pressure towards roadways, reducing the extent of abutment stress, and ultimately alleviating stress and deformation within the surrounding rock formation.

Variable pressure differential fuzzy control method for the multi-split backplane cooling system in data center

In contrast to existing room-level cooling systems, rack-level cooling systems can solve local hot spot issues due to their on-demand cooling way with higher energy efficiency and higher supply cooling temperatures. However, the multi-split backplane cooling system, which is a typical rack-level cooling way, makes it easy to cause insufficient refrigerant supply problems due to higher evaporating pressure under the same ambient condition. To solve above problems, a suitable condensing pressure relative to evaporating pressure is a critical optimized parameter, which needs to follow with the change of ambient condition. Therefore, a variable pressure differential control method between the condensing side and the evaporating side is proposed based on online fuzzy inference. A Modelica-based simulation model is built to validate the proposed method. Results show that the proposed method can ensure the terminal cooling effect at different ambient temperatures. Compared with the fixed condensing pressure control method, the proposed method shows an increase of 13.3% in system coefficient of performance (COP) with lower condensing pressure.

A pressure control method for increasing the energy efficiency of the hydraulic system powering agricultural implements

Agricultural tractors and their implements are at the basis of modern farming. Besides propulsion, in such system, most of the mechanical actuations are performed with a fluid power system that is highly power-dense and versatile, but has a low energy efficiency. This article first describes the challenges of the state-of-the-art hydraulic system that cause poor efficiency. Afterward, it proposes and demonstrates a solution that can significantly increase such efficiency without affecting the cost and functionality of the overall hydraulic control system. The proposed solution is based on a peculiar control approach to the hydraulic supply units that power the implement functions through the hydraulic remote connections. The approach is based on an impressed-pressure control methodology, as opposed to the traditional impressed flow method used in off-road machinery. The result is that the typical energy-inefficient pressure saturation conditions that often occur in common vehicles are mitigated and brought to a more efficient state. To support the development of the technology, the research takes into consideration the circuit of a 400-hp tractor and a 16-row planter. A simulation model of the hydraulic system of the two vehicles was implemented and validated against experiments. The model was then utilized to estimate the reduction in the energy consumption achieved by the proposed solution. Lab tests and field experiments of the proposed solutions applied to the reference tractor and planter system confirmed an overall 18% energy efficiency improvement.

Research on a Pressure Control Method for a Liquid Supply System Based on Online Updating of a Radial Basis Function Neural Network

In order to solve the problem of frequent pressure fluctuations caused by fluid quantity variation in hydraulic support liquid supply systems and the pressure response lag caused by long-distance pipelines, an online updated radial basis function neural network (RBF neural network) control method was proposed for the long-distance liquid supply system. Based on the analysis of the measured pressure fluctuations of the mining face and the process of the stable pressure liquid supply system, the influencing factors of the stable pressure liquid supply flow demand were obtained. The flow set of the stable pressure liquid supply system was established and fitted in the SimulationX–Simulink co-simulation model and the online correction was carried out by using the characteristics of the repeated action of the hydraulic support. Finally, the online updating RBF neural network regulator was established to realize the pressure regulator control of the pumping station, and the experimental platform was set up for verification. The results show that this method can effectively reduce the pressure fluctuations caused by the change in the flow demand of the mining face, and can adjust the flow rate of the mining face, reduce the pressure impact, and improve the efficiency of the machine.

Design of nonlinear control method for pressure of pintle solid rocket motor

A pressure control method that incorporates parameter adaptation has been devised for the pressure control system of pintle solid rocket motors, which exhibit notable nonlinearities and uncertainties in parameters. Firstly, the mathematical relationship between pressure and pintle displacement is derived using the zero-dimensional interior ballistic model., and the state space equation is deduced by incorporating the dynamics of motor inertia load. Secondly, by capitalizing on the robustness of robust control, the parameter identification capabilities of adaptive control, and the rigor of Lyapunov stability theory, the proposed approach enables precise control of the pintle position while effectively addressing uncertainties, thereby enhancing the overall performance and stability of the system. Finally, the aforementioned theoretical framework has been validated through rigorous numerical simulations. The findings demonstrate a notable enhancement in the pressure response speed of the adaptive robust controller, with improvements of 10.01 % and 13.16 %, 0.03 % and 1.54 %, 0.06 % and 22.39 % in different orders of magnitude of free volume as compared to the robust controller and PID controller, respectively. Moreover, it is evident that the adaptive robust controller relies on the accuracy of the model. The applied controller demonstrates notable advantages in terms of stability, robustness, and accuracy, thereby substantially enhancing the overall performance of the pressure control system.

A novel constant pressure control method for nucleation boiling of CO2/lubricant in molecular dynamics simulation

Conventional molecular dynamics simulations of nucleation boiling typically employ the fixed volume method, resulting in a non-constant pressure during the boiling process. In this paper, we propose an additional pressure control method, placing a cover plate at the top of the liquid phase to achieve liquid phase pressure control during boiling. The novel method yields a pressure control error within ±5 %. CO2 and CO2/PEC4 lubricating oil mixture are used to investigate the differences in heat transfer characteristics between non-constant and constant pressure nucleation boiling. Furthermore, the effect of PEC4 lubricating oil on CO2 nucleation boiling under a fixed pressure condition is explored. The results show that both the bubble nucleation and growth time of CO2 and the CO2/PEC4 mixture are prolonged under constant pressure. This causes a compression in CO2 molecular spacing, thereby reducing CO2 diffusion and mass transfer capabilities. Heat transfer from the solid to the liquid, and within the liquid itself, is diminished, while the distribution of PEC4 molecules within the liquid phase becomes more even. The migration rate of PEC4 molecules in the liquid phase slows down. Under the constant pressure model, PEC4 increases the mass transfer resistance of CO2. As the lubricant mass fraction rises, The nucleation and growth rate of CO2 bubbles decline. In comparison to CO2, PEC4 molecules exhibit a stronger interaction energy with the Cu wall surface. During boiling, some PEC4 molecules accumulate on the Cu surface, forming an oil film that impedes the direct contact between CO2 molecules and the Cu wall.

Dependency of Pressure Expression towards Formation Pressures during Drilling Operations in Hydrocarbon Wells and Suitable Choice of Pressure Control Method

High pressures during drilling with the aim to obtain hydrocarbon formations (oil and natural gas) can cause an uncontrolled eruption. Therefore, it is necessary to look for warning signs of kicks and control the formation strength. The aim of this article is to show a real process of fracture pressures during a gas kick and their possible solutions. The evaluation of the lithological structure of formations and the correct evaluation of seismic measurements are closely related to the issue of fracture pressures. The contribution also includes software data for detailed analysis and calculations of formations pressures. We point out the incorrect calculation of the geological lithology and employ a casing shoe; it is a risky decision to use a formation integrity test as opposed to a leak of the test. Based on theoretical knowledge, we compared and verified the recalculation of pressure coefficients during the gas kick. In our case, we propose possible solutions for cracking a casing shoe. We point out the importance of correct calculations for a safe and economical purpose. In this post, a theoretical example was shown where the system of casings was correctly designed, and based on this, we obtained ideal values of the fracture pressures. In the end, we proposed an algorithm to simplify work procedures during well control to minimize formation pressures against the deposit and casing shoe.

A Wellbore Pressure Control Method for Two-Layer Coal Seam Gas Coproduction Wells

In coal seam gas (CSG) coproduction wells, due to the different production pressures of CSG production layer at different depths, the interlayer interference in wellbore seriously affects the gas production of a coproduction well. To effectively suppress the interlayer interference of the wellbore, a wellbore pressure distribution method for a two-layer coproduction well is proposed. Based on the analysis of the factors influencing the flow pressure distribution in the wellbore of two-layer coproduction wells, a method of coproduction flow pressure adjustment by regulating the wellhead pressure and the depth of the dynamic fluid level was established in this paper. The results show that wellhead pressure can directly affect the production pressure of two layers. The variation in layer 1 output mainly affects the pressure difference between the wellhead pressure and the pressure at the depth of layer 1, which has little effect on the pressure difference between layer 1 and 2. An increase in gas production from layer 2 would not only cause a pressure increase in layer 1, but also result in a reduction of the production pressure at layer 2. The maximum pressure gradient of the gas section is 0.14 MPa/100 m, and the pressure gradient of the gas–liquid section is 0.53–1.0 MPa/100 m.

Pressure control for pneumatic pressing roller in automated fiber placement

In automated fiber placement (AFP), the contact pressure between the roller and the mold is an important process parameter. Too small or too large contact pressure will result in unacceptable laying defects. This paper focuses on the control method of contact pressure in AFP. Firstly, the dynamic model of the pressing foot mechanism is established, and a mathematical relationship of input air pressure and output force is developed. Then, a self-tuning PI control algorithm is used to implement servo control of the roller output force based on the Slowly Time-Varying Recursive Identification Algorithm. Also, using Abaqus/CAE, the mapping relationship between the contact area and measurements from displacement sensors is established to predict the contact area in real time. Finally, the contact pressure control method is established by combining the servo control method of contact force and the prediction method of contact area. Experimental results show that the constant pressure control method can effectively stabilize the contact pressure, with a pressure fluctuation of less than 4% under the experimental conditions set in this paper.

Research on a Hydraulic Cylinder Pressure Control Method for Efficient Traction Operation in Electro-Hydraulic Hitch System of Electric Tractors

The tractor is the primary power device of the agricultural production process. For the problem that the traditional electro-hydraulic hitch control method for tractors cannot simultaneously meet the requirements of maintaining a constant ploughing depth and improving traction performance and electric tractor overall efficiency, this paper proposes a hydraulic cylinder pressure control method of the electro-hydraulic hitch system for electric tractors. We establish a tractor-implement system dynamic model, calculate the rear axle load of the tractor in real-time according to the actual working parameters under the premise of ensuring the constant ploughing depth, construct a traction performance objective optimization function, and use the genetic algorithm to solve the optimal hydraulic cylinder pressure value of the electro-hydraulic hitch system. Hardware-in-the-loop (HIL) simulation results show that the electric tractor under the traditional position control method and the hydraulic cylinder pressure control method has an average wheel slip of 18.50% and 16.93%, an average traction efficiency of 71.35% and 73.08%, and an average overall efficiency of 50.81% and 52.40%. The hydraulic cylinder pressure control method proposed in this paper reduces the wheel slip by 9.27%, increases the traction efficiency by 2.42%, improves the electric tractor overall efficiency by 3.13%, and reduces the electric tractor overall energy loss by 7.67% compared with the traditional position-control method. Therefore, the hydraulic cylinder pressure control method of the electro-hydraulic hitch system proposed in this paper can achieve the purpose of effectively improving tractor traction performance and reducing tractor energy loss while maintaining a constant ploughing depth. This study offers technological references for electric tractors to improve traction performance and reduce the overall energy loss of electric tractors.

A study of the fixed choke and constant outflow method for riser gas handling

Riser gas events appear during offshore drilling operations when there is a presence of gas in a marine riser above the subsea BOP, which has been recognized as a hazardous situation. The selection of pressure control methods during such events significantly impacts the safety and efficiency of riser gas handling (RGH). This paper performed a numerical simulation study on the fixed choke and constant outflow method as one of the most discussed and positively perceived pressure control methods for RGH currently in the industry. The processes of RGH with the proposed fixed choke and constant outflow method were simulated with a comprehensive riser gas influx simulator. The multiphase flow dynamics in a riser were simulated by a drift-flux model with the inclusion of various sub-models and coupled with a multiphase choke flow model. Measurement data (including distributed fiber optic sensing data) from a set of full-scale experiments conducted at the Petroleum Engineering Research, Training, & Testing (PERTT) Laboratory at Louisiana State University (LSU) was used for the calibration and validation of the developed simulator. The performance of the proposed method is evaluated based on the maximum gas and liquid outflow rates and the peak choke upstream pressure during RGH. A series of sensitivity analyses and a contingency case study was conducted to evaluate the applicability and the extendibility of the fixed choke and constant outflow method. The proposed pressure control method shows great potential in enhancing the safety of RGH for a wide range of riser lengths and gas influx sizes with the available managed pressure drilling (MPD) and riser gas handling equipment. The sensitivity analyses revealed that the selection of the initial circulation rates and choke positions has a significant impact on the safety and time efficiency of the RGH operations and should be carefully determined based on the influx and riser system status. This study deepens the understanding of gas influx movement and pressure behaviors in a marine riser during riser gas events. The numerical simulations in this study help to improve the design of riser gas handling strategies.

Investigation of effective invasive blood pressure control methods to prevent acute exacerbation of acute aortic dissection.

Acute aortic dissection is associated with high mortality and increased risk of complications. Acute exacerbations have a relatively high frequency; however, the contributing factors are unclear. Blood pressure (BP) and heart rate control are important factors, but the ideal BP control strategy to prevent acute exacerbations under invasive arterial pressure monitoring remains unclear. Therefore, in this study, we aimed to determine the relationship between invasive arterial BP and the effects of acute exacerbation of aortic dissection. This single-centre, retrospective, case-control study included 104 patients with a partial diagnosis of acute aortic dissection (Stanford type A or B) who were treated conservatively between September 2013 and September 2022. The patients were divided into exacerbation (acute exacerbation; n = 26) and stable (no acute deterioration) groups. The SBP trend (122.5 ± 13.1 vs. 116.6 ± 10.6 mmHg, respectively; P = 0.024) and mean BP trend (77.8 ± 5.8 vs. 74.4 ± 7.5 mmHg, respectively; P = 0.038) significantly differed between the two groups. The time to target BP was significantly longer in the exacerbation group ( P = 0.036). The exacerbation group did not achieve a mean SBP < 120 mmHg. Moreover, the importance of early BP reduction was demonstrated in the present study.

Study on Dynamic Pressure Control of Air-Breathing Hypersonic Vehicle

To satisfy the strict requirements of dynamic pressure for air-breathing hypersonic vehicle during the initiation, a dynamic pressure control method based on the model reference sliding mode theory is designed. Firstly, the motion equation of the air-breathing hypersonic vehicle is built, and the dynamic pressure linearization model is established by the small perturbation method. Secondly, the control system, designed by the model reference sliding mode control theory, can quickly track the reference model. Finally, the six degrees of freedom simulation model is built and used for digital simulation. The simulation results show that the designed control system can accurately track the dynamic pressure command with great robustness.

Precision agricultural robotic sprayer with real-time Tobacco recognition and spraying system based on deep learning.

Precision agricultural techniques try to prevent either an excessive or inadequate application of agrochemicals during pesticide application. In recent years, it has become popular to combine traditional agricultural practices with artificial intelligence algorithms. This research presents a case study of variable-rate targeted spraying using deep learning for tobacco plant recognition and identification in a real tobacco field. An extensive comparison of the detection performance of six YOLO-based models for the tobacco crop has been performed based on experimentation in tobacco fields. An F1-score of 87.2% and a frame per second rate of 67 were achieved using the YOLOv5n model trained on actual field data. Additionally, a novel disturbance-based pressure and flow control method has been introduced to address the issue of unwanted pressure fluctuations that are typically associated with bang-bang control. The quality of spray achieved by attenuation of these disturbances has been evaluated both qualitatively and quantitatively using three different spraying case studies: broadcast, and selective spraying at 20 psi pressure; and variable-rate spraying at pressure varying from 15-120 psi. As compared to the broadcast spraying, the selective and variable rate spray methods have achieved up to 60% reduction of agrochemicals.