Pressure Control System Research Articles

Factors Affecting Audit Quality (Survey at Public Accounting Firms in Bandung and Jakarta)

The aim of this study is to determine the factors that affect the quality of the audit. The sampling technique used is convenience sampling, with the Public Accounting Firm's unit of analysis, the respondents were auditors who served in the Public Accounting Firm (KAP) in Bandung and Jakarta, and obtained a sample of 39 respondents from 12 public accounting firms. The analytical method used is multiple regression analysis at a significance level of 5% with an analysis tool using SPSS 25, which shows the partial results of Time Budget Pressure and Quality Control System affect Audit Quality and both of these variables simultaneously have an effect on Audit Quality

Optimization Technology of Frequency Conversion Constant Pressure Control System of Mine Emulsion Pump Station in Electrical Engineering and Automation Specialty

No matter in metal mines or coal mines, an emulsion pump station has a wide range of application market and can play an important role. In this paper, the frequency conversion constant pressure control system of the mine emulsion pump station is taken as the research object. The two kinds of water-based drawing fluids used are dispersed drawing fluid and emulsion drawing fluid. After the intelligent level of the equipment reaches a very high level, an environmentally friendly, safe, and efficient Internet of Things technology system will be added. Combined with 3D laser scanning technology based on self-scanning of road contours, the blast method is input to the terminals of the emulsion pump station for automatic blast hole positioning and semiautomation of the emulsion pump station. Combined with 5 g communication and other intelligent key technologies, it realizes high-end functions such as fault self-diagnosis, remote operation, and remote monitoring of the emulsion pump station and rock drill, which can be called full intelligent stage. The results show that the initial friction coefficient of drawing fluid A lubrication is 0.21, and then, with the extension of time, the friction coefficient gradually decreases to 0.14. The initial friction coefficient of drawing fluid B is 0.22, then it decreases rapidly to 0.13, then it is stable at 0.17, and then it remains basically unchanged. When the temperature is 55°C, the initial friction coefficient is 0.16 and then decreases to 0.12. Therefore, the frequency conversion constant pressure control system of the mine emulsion pump station should be selected according to the environment and application scenarios.

Simple Adaptive Control-Based Reconfiguration Design of Cabin Pressure Control System

The Cabin Pressure Control System (CPCS) is an essential part of the aviation environmental control system that ensures aircraft structure and flight crew safety. However, the CPCS usually has potential faults of sensors and actuators. To this end, a Simple Adaptive Control- (SAC-) based reconfiguration method is proposed to compensate for the above adverse effects. Some good pressure control performance of CPCS can be achieved by the basic pressure controller when the system is in normal operation. A parallel feedforward compensator is designed to guarantee the closed-loop system’s stability and the almost strictly positive realness of the augmented system. Thus, the simple adaptive controller can be utilized for the CPCS. In particular, the reconfiguration system can update the control law online when the fault occurs without the system identification process. The reference model is obtained by mathematical model linearization after considering the mechanical characteristics of the CPCS. Extensive simulations under various typical fault scenarios are carried out throughout the entire flight envelope of the aircraft from take-off to landing. Simulation results validate the robustness and reconfiguration control capability of the proposed method.

Analysis of the effect of pressure control on leakages in distribution systems by FAVAD equation and field applications

Abstract Pressure has an important effect on the occurrence of failures/leaks in water distribution systems (WDSs) or the change of leakage in existing leakages. For this reason, monitoring the pressure is important especially for analyzing the changes in the day and night, determining the fluctuations and applying pressure management (PM) to ensure normal operating conditions. In this study, the effect of pressure on water losses and minimum night flow (MNF) was carried out according to the Fixed and Varied Area Discharge (FAVAD) approach, which allows the amount of leakage to be calculated based on the change in pressure and field tests. The minimum flow rate and potential leakage were determined under the network operating conditions before the pressure control in a region. Then, considering the features of the region, pressure was reduced with the pressure control system and MNFs and leaks were monitored. By reducing the pressure from 9.10 bar to 3.2 bar in the region, the MNF rate was reduced from 6.95 l/s to 3.29 l/s. The daily water savings in the system inlet volume is 78.44 m3/day and the annual saving is 28,624 m3/year. The results obtained are very important for practitioners in terms of implementing PM in the field.

Innovative Pressure Control System for Metallurgical Enterprises

The present study considers an innovative pressure control system for improving reliability of a hydraulic descaling plant. The pressure control system is based on a metal bellows hydraulic accumulator capable of withstanding high pressures. System installation diagram in the hydraulic descaling plant is shown. Design of the hydraulic accumulator is shown. This design allows effective pressure control in the whole plant due to its features of effective forces distribution on additional elastomerics. The materials that can be used to create elastomerics taking into account the peculiarities of metallurgical shops are shown. Dependencies are obtained which show possibility of reducing stiffness of the metal bellows unit when using additional elastomerics. This reduces the cost of the pressure control system by using the metal bellows unit materials with less stiffness.

New X-Ray Microtomography Setups and Optimal Scan Conditions to Investigate Methane Hydrate-Bearing Sand Microstructure

Abstract Methane hydrates, which are naturally formed at high pressures and low temperatures in marine and permafrost sediments, represent a great potential energy resource but also a considerable geo-hazard and climate change source. Investigating the grain-scale morphology of methane hydrate-bearing sandy sediments is crucial for the interpretation of geophysical data and reservoir-scale simulations in the scope of methane gas production as methane hydrate morphologies and distribution within the porous space significantly impact their macroscopic physical/mechanical properties. X-ray computed tomography (XRCT) and synchrotron X-ray computed tomography (SXRCT) are commonly used to analyze the microstructure of geo-materials. However, methane hydrates exist only at high pressures (up to several megapascals) and low temperatures (a few degrees Celsius). This article describes the development of three experimental setups, which aim at creating methane hydrates in sandy sediment, adapted to XRCT and SXRCT observations. The advantages and drawbacks of each setup are discussed. The discussions focus on the effects of the choice of the system to control temperature and pressure on the quality of images. The obtained results would be useful for future works involving temperature control systems or pressure control systems, or both, adapted to XRCT and SXRCT observations of various geo-materials.

Automated Tire Pressure Control System for Multi-Purpose Wheeled Vehicles

The cross-country capability of multi-purpose wheeled vehicles is one of the most important operational properties of these technical objects. In many ways, it is determined by their traction characteristics. There are a number of ways to improve traction and coupling properties of multipurpose wheeled vehicles, the main ones are the use of various kinds of traction control systems, blocking of interaxle and interwheel differentials, the use of ballast and several others. Recently, one of the ways to improve the traction properties and cross-country ability of vehicles on soils with weak load-bearing capacity is a regulation of air pressure in the tires of the driving wheels of multi-purpose wheeled vehicles. The paper describes the process of interaction of the wheel mover with the ground surface when the air pressure in the tire changes. The influence of air pressure on the traction properties of wheeled vehicles is established. The system of automatic control of air pressure in tires of mobile cars depending on road conditions is offered. The use of the proposed regulation principle will significantly increase the cross-country ability of multi-purpose wheeled vehicles in heavy traffic conditions, eliminating the subjective factor in the person of the vehicle operator.

Design and Analysis on Mixed Line Welding Fixture for Light vehicle

The existing welding has some defects that can only be used for a single type of vehicle body and cannot apply to mixed line welding for several vehicle types. According to the structure characteristics and normalization design requirements of body welding fixture, the existing four light vehicle body structure parameters, clamping fixture and welding process requirements are analysed, so that a modular fixture which is suitable for four kinds of light vehicle body with mixed line repair welding is designed, which includes flexible clamp concrete, pressure control system, the single-chip microcomputer control, and mixed line of three kinds of switch control method.

Optimization of back pressure control of direct air-cooling unit based on GPC

In view of the fact that the actual back pressure is difficult to track the set value quickly and stably, this paper applies the predictive control algorithm (GPC) which can respond quickly, has good robustness and is easy to realize in the industrial production site to optimize the back pressure control. The control performance of the back pressure control system with PID, fuzzy PID and GPC is compared and analyzed through the simulation test. The simulation results show that the GPC algorithm has better dynamic performance than PID and fuzzy PID control in the case of set point disturbance and internal disturbance, and has stronger robustness in the face of model mismatch. To sum up, GPC algorithm is more suitable for the back pressure control system under complex working conditions, and the optimization control method has a certain guiding significance for the actual production site back pressure control strategy improvement.

Automatic control of groundwater balance to combat dewatering during construction of a metro system

The construction of a metro system in groundwater-rich stratums can cause an imbalance in groundwater levels. This study presents an automatic pumping-recharge system (APRS) to maintain groundwater balance during dewatering, thereby protecting the environment. The APRS overcomes the limitations of the traditional pumping-recharge operation performed manually by workers. Further, in traditional pumping-recharge operations, a large proportion of the pumped water is wasted by draining it into the sewerage system; this is because of the lack of an efficient application for groundwater recharge. The developed APRS system includes three subsystems: i) a pressure control system, ii) an integrated process system, and iii) an intelligent electronic control system. The APRS can not only balance the groundwater system but also control the settlement during underground construction. The proposed system has been employed in the construction of a metro station in Jinan city, which has a dense distribution of spring groups. The efficiency of the APRS was verified by field observations.

Field Performance Evaluation of Pulse-Width Modulation and Pressure-Controlled, Fixed-Orifice Application Systems for Sensor-Based Nitrogen Applications

HighlightsComparison of PC system and PWM system in-field performance indicated that the PWM system made sensor-based N applications more accurately than the PC system.The turndown ratio calculated from the aggregate application instances was 6.2:1.For both the PWM system and the PC system, applications were made more accurately when 28% UAN was applied rather than 32% UAN. Abstract. Sensor-based nitrogen (N) applications have shown promise for improving N use efficiency, but present significant challenges for application rate control due to highly variable and frequently changing target rates. If applications are to be made precisely, equipment systems used for sensor-based N applications must be designed to meet system demands. Pulse-width modulation (PWM) equipped systems have emerged as a technological advancement over traditional pressure-controlled (PC) systems for improving variable rate N application accuracy. Little research, however, has been done to assess the performance of PWM systems during sensor-based N applications in-field. This work analyzed as-applied data collected from in-field sensor-based N applications with pressure-controlled (PC) and PWM systems in Nebraska between 2015 and 2017 to quantify system requirements, assess system performance, and determine performance impacting operational variables. It was found that systems should be capable of 1-s rate changes of ±71.1 L ha-1 (7.6 gpa), 1-s flow rate changes of ±11.4 L min-1 (3 gpm), and turndown ratios of at least 6:1. PWM systems achieved application rates within 10% of the target rate 10% more often than PC systems, and showed less variability in application error. However, PWM systems still demonstrated significant application errors with an observed RMSE of 44.9 L ha-1 (4.8 gpa). Speed change magnitude was found to be most associated with increases in percent application error. These findings substantiate that PWM systems effectively improve sensor-based N application accuracy versus traditional PC systems. However, collaborative efforts toward greater cohesion between sensor-based application expectations and application equipment capabilities are necessary for maximizing the effectiveness of sensor-based N applications. Keywords: Precision agriculture, Rate controllers, Site-specific crop management, Sprayer, Turndown ratio.

Development of a High Temperature and High Pressure Oil-Based Drilling Fluid Emulsion Stability Tester

When drilling deep wells and ultra-deep wells, the downhole high temperature and high pressure environment will affect the emulsion stability of oil-based drilling fluids. Moreover, neither the demulsification voltage method nor the centrifugal method currently used to evaluate the stability of oil-based drilling fluids can reflect the emulsification stability of drilling fluids under high temperature and high pressure on site. Therefore, a high-temperature and high-pressure oil-based drilling fluid emulsion stability evaluation instrument is studied, which is mainly composed of a high-temperature autoclave body, a test electrode, a temperature control system, a pressure control system, and a test system. The stability test results of the instrument show that the instrument can achieve stable testing and the test data has high reliability. This instrument is used to analyze the factors affecting the emulsion stability of oil-based drilling fluids. The experimental results show that under the same conditions, the higher the stirring speed, the better the emulsion stability of the drilling fluid; the longer the stirring time, the better the emulsion stability of the drilling fluid; the greater the oil-water ratio, the better the emulsion stability of the drilling fluid. And the test results of the emulsification stability of oil-based drilling fluids at high temperature and high pressure show that under the same pressure, as the temperature rises, the emulsion stability of oil-based drilling fluids is significantly reduced; at the same temperature, the With the increase in pressure, the emulsion stability of oil-based drilling fluids is in a downward trend, but the decline is not large. Relatively speaking, the influence of temperature on the emulsion stability of oil-based drilling fluids is greater than that of pressure.

A four-channel air pressure cooperative control system for 3-D bio-printing device

In recent years, the research and development of 3D bioprinting device for artificial blood vessels has attracted great attention of researchers. In this paper, the research object is the control system of 3D bioprinting device for artificial blood vessel and the four-channel air pressure cooperative control technology for 3D bioprinting device double nozzles printing is mainly studied. Through the scheme design, working principle innovation, hardware selection and air pressure output calibration experiment of four-way air pressure cooperative control system, the hardware platform of 3D bioprinting device air pressure control system is built. Then, by using the embedded TwinCAT NC PTP software platform based on EtherCAT Ethernet bus protocol, the four-channel air pressure cooperative control is programmed and field experiments are carried out, which realizes the printing process of uniform liquid output and good continuity, and meets the requirements of 3D bioprinting for printing continuity and forming quality. The study of four-channel air pressure cooperative control system in this course is a worthy of application and promotion control method.

Sensor Fault Diagnosis of Locomotive Electro‐Pneumatic Brake Using an Adaptive Unscented Kalman Filter

Normal operation of the pressure sensor is important for the safe operation of the locomotive electro‐pneumatic brake system. Sensor fault diagnosis technology facilitates detection of sensor health. However, the strong nonlinearity and variable process noise of the brake system make the sensor fault diagnosis become challenging. In this paper, an adaptive unscented Kalman filter‐ (UKF‐) based fault diagnosis strategy is proposed, aimed at detecting bias faults and drift faults of the equalizing reservoir pressure sensor in the brake system. Firstly, an adaptive UKF based on the Sage‐Husa method is applied to accurately estimate the pressure transients in the equalizing reservoir of the brake system. Then, the residual is generated between the estimated pressure by the UKF and the measured pressure by the sensor. Afterwards, the Sequential Probability Ratio Test is used to evaluate the residual so that the incipient and gradual sensor faults can be diagnosed. An experimental prototype platform for diagnosis of the equalizing reservoir pressure control system is constructed to validate the proposed method.

Pressure-Driven Fiber-Optic Sensor for Online Corrosion Monitoring

For many industrial applications, corrosion is a life-limiting phenomenon and therefore requires careful consideration and rigorous experimental testing before structural materials can be reliably deployed, particularly in harsh chemical environments. The traditional approach to measuring corrosion requires exposing many samples to the intended environment and then extracting them individually at discrete intervals for postexposure characterization. This approach does not provide a high degree of temporal resolution, nor does it provide any real-time information regarding dynamic changes in corrosion rates. Developing an online corrosion monitor capable of surviving harsh chemical environments could provide valuable information regarding the structural health of components and changing process conditions that could accelerate corrosion. To this end, a corrosion sensor was developed based on a pressure-driven Fabry-Pérot cavity (FPC). This sensor uses a pressure control system to internally pressurize the FPC formed between the sensor's housing and a metal-embedded singlemode optical fiber. Simultaneous measurement of the change in FPC length using low-coherence interferometry and the applied pressure enables the calculation of the relative changes in the sensor's diaphragm thickness due to corrosion on its outer surface. Measurements were made in situ while actively corroding the sensor and were validated against surveillance specimens that were corroded simultaneously. The uncertainties in the measured corrosion were analyzed using error propagation of the uncertainties in the measured pressures and displacements and were found to be <; 1% of the initial diaphragm thickness.

A developed analytical model for the pressurizer unit in nuclear power plants

ABSTRACT The pressure control in the pressurized water reactor (PWR) primary loop is key to secure the safe operation. The pressurizer (PZR) unit is responsible for attaining this task. Thus, the PZR unit’s modeling is an important issue for the tracking control purpose and performance analysis concerning the turbine load. This paper develops a mathematical model to accurately predict the PZR unit pressure in the normal and load power changes. The model is a non-equilibrium three region model developed based on the thermodynamics of mass and energy for the water and steam in the PZR. The variations of the pressure and the temperature due to thermodynamic variables (enthalpy, density) and the mechanical work effect are considered in the developed model. The model also addresses other thermodynamic processes such as bulk flashing, spray condensation, interface condensation, wall condensation, and rainout flow. The inlet and outlet flow rates of the primary circuit (PC) and the average temperature and the hot leg temperature are included in the developed model. Based on data generated from the VVER-1200 simulator, parameter estimation, verification, and validation of the developed model through load power changes are achieved. Besides, a comparison with other models given in literature has been performed. This comparison indicated that the developed model is more sensitive against the minimum variation of PZR dynamics. Finally, a closed-loop PZR pressure control system, including a conventional Proportional Integral Derivative (PID) controller, was designed to test the control purpose’s developed model. The simulation results over typical load change transients have been demonstrated the feasibility, effectiveness, and accuracy of the developed nonlinear model of PZR for dynamic modeling and control purposes.

Dural repair efficacy assessment of different techniques, a cadaveric study comparing the naked eye and surgical loupes

Background: Watertight dural repair is crucial to achieve successful dural tear sutures. Microscopic or surgical loupes are recommended to use to magnify and assist repairing the dura. However, many spine surgeons repair dural tears under the naked eye. The efficacy of repairing dural tears by the naked eye compared with microscopic or surgical loupes has never been studied. Objective: This study aimed to compare the efficacy of dural repairing techniques using the naked eye or surgical loupes. Methods: A cadaveric experimental study was conducted. Four fresh human cadaveric specimens were used to harvest the spinal cord. Dural tear and CSF leakage were simulated with a water pressure control system (Arthrex AR-6475 arthroscopic pump). We compared surgical repair using the naked eye and surgical loupes. Surgical closure was achieved using Prolene 6-0 and Durepair®. A total of 32 experimental dural tears were subdivided to four groups. The 4 groups were Prolene6-0 with the naked eye (n=8), Prolene 6-0 with surgical loupe (n = 8), Durepair® with the naked eye (n=8) and Durepair® with surgical loupe (n=8). The total time used for sutures and postsuture CSF water leakage pressure were recorded and compared among the subgroups. Results: Our results showed that surgical loupe assisted dural closure and sutures were significantly faster than the naked eye in both Prolene 6-0 (surgical loupe = 4.87±0.19 min, naked eye = 7.18±0.36 min, p <0.001) and Durepair® groups (surgical loupe = 9.84±0.21 min naked eye = 13.27±0.42 min, p <0.001). CSF Leakage pressure in the surgical loupe groups were higher than in the naked eye groups in both Prolene 6-0 (surgical loupe = 100.00±5.35 mmHg, naked eye = 96.88±7.99 mmHg, p = 0.373) and Durepair® (surgical loupe = 96.88±4.58 mmHg, naked eye = 95.63±4.17 mmHg, p = 0.577) but without significant difference. Prolene 6-0 was significantly faster to use for sutures than Durepair® in both sutures by the naked eye and surgical loupe assisted (p <0.001). Prolene 6-0 showed a higher leakage pressure than Durepair® in both the naked eye and surgical loupe assisted sutures but without significant difference (naked eye, p = 0.701, surgical loupe, p = 0.230) CONCLUSION: Repairing a dural tear without using surgical loupes consumed more time and did not achieve similar maximum leak pressure compared with using surgical loupes. However, no statistically significant difference was observed in terms of CSF leakage pressure. Durepair® consumed more time than Prolene 6-0 while leakage pressure was similar. We recommended the use of surgical loupes when performing dural repair. Durepair® is suitable to repair larger dural defects that cannot be closed using a simple suture technique.

Diabetic Nephropathy: Novel Molecular Mechanisms and Therapeutic Targets.

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes mellitus and the leading cause of end-stage kidney disease. The standard treatments for diabetic patients are glucose and blood pressure control, lipid lowering, and renin-angiotensin system blockade; however, these therapeutic approaches can provide only partial renoprotection if started late in the course of the disease. One major limitation in developing efficient therapies for DN is the complex pathobiology of the diabetic kidney, which undergoes a set of profound structural, metabolic and functional changes. Despite these difficulties, experimental models of diabetes have revealed promising therapeutic targets by identifying pathways that modulate key functions of podocytes and glomerular endothelial cells. In this review we will describe recent advances in the field, analyze key molecular pathways that contribute to the pathogenesis of the disease, and discuss how they could be modulated to prevent or reverse DN.

Design Features of the User Interface of the Pipeline Pressure Control Monitoring System

For control and regulation of hydraulic systems, especially, oil pumping stations, automatic pressure control systems (APCS) are used. Using it, the monitoring, controlling, and adjusting the operation of technological equipment, optimization of modes, and other tasks that require direct human participation become possible. The operator (or dispatcher) interacts with the system via a human-machine interface. The monitoring system includes programs for collecting, processing, displaying, and archiving information about the object of observation and control. Well-suited and being put to the right user interface design promotes not only the effective interaction of the operator with the system in normal conditions but also prevents errors and helps to find a solution in a dangerous or emergency swiftly. This paper presents a software package designed for real-time monitoring and regulation of pipeline operation. A system simulation model is provided for the teaching and training of site personnel.

A disposable smart microfluidic platform integrated with on-chip flow sensors

Microfluidic devices are powerful tools for biological, biomedical, chemical, and pharmaceutical applications, but their commercialization is still hindered by the lack of methods to automatically control fluid flow in a low-cost, simple, accurate, and safe manner. This study introduces a disposable smart microfluidic platform (DIS-μChip), which can be fully automated and utilized for a wide range of applications. On-chip microfluidic flow sensors are integrated with the platform and placed at all inlet and outlet channels, thereby allowing the DIS-μChip to be fully automated with a pressure control system. Furthermore, these confer a self-diagnosis function through monitoring of all the input and output flow rates. The DIS-μChip consists of a disposable polymeric microchannel superstrate and a permanent multifunctional substrate, which could be assembled and disassembled using only vacuum pressure. The superstrate was fabricated by combining a polydimethylsiloxane microchannel structure with a polyethylene terephthalate (PET) thin film. The substrate contains sense electrodes for the on-chip-integrated flow sensors and functional components for creating an energy field, which can penetrate the PET thin film and manipulate the fluid in the microchannels of the superstrate. Owing to the film-chip technique, the superstrate was disposable and could prevent biological cross-contamination, which cannot be realized with conventional flow sensors. The usefulness of the DIS-μChip was demonstrated by using it to isolate circulating tumor cells from the blood of patients with pancreatic cancer and to obtain cancer-specific genetic information from them with droplet digital PCR.