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Records with Subject: Process Control
Showing records 2472 to 2496 of 3434. [First] Page: 1 96 97 98 99 100 101 102 103 104 Last
Research and Development of Adjustable Discontinuous Pulse Width Modulation Method for Three-Phase Voltage Source Inverter
Andrey Dar’enkov, Victor Sokolov, Anton Sluzov, Ivan Berdnikov, Andrey Shalukho
February 24, 2023 (v1)
Keywords: continuous pulse width modulation, discontinuous pulse width modulation, dynamic losses, total harmonic distortion, voltage inverter
Continuous pulse width modulation (CPWM) and discontinuous pulse width modulation (DPWM) strategies are used to control voltage source inverter operation. CPWM strategies allow for the reduction of total harmonic distortion values, while DPWM strategies provide a more effective reduction in inverter switching losses. The paper is devoted to the problem of improving the three-phase voltage source inverter efficiency by a controlled transition from CPWM to DPWM. The article proposes an adjustable discontinuous pulse width modulation (ADPWM) method, which means a transition from space vector PWM (refers to CPWM strategies) to DPWM in all inverter phases when the switches’ temperatures exceed the allowable value in at least one of the inverter phases. The method flowchart is presented and an algorithm for modifying the envelope curve within one sector is given. In order to test the ADPWM method a Simulink-model of a three-phase voltage source inverter and its control system were developed.... [more]
Roof Fall Hazard Monitoring and Evaluation—State-of-the-Art Review
Krzysztof Fuławka, Lech Stolecki, Marcin Szumny, Witold Pytel, Izabela Jaśkiewicz-Proć, Michel Jakić, Michael Nöger, Philipp Hartlieb
February 24, 2023 (v1)
Keywords: ground control, monitoring systems, roof fall hazard
A roof fall hazard is still one of the major threats in the underground mining industry. Each such type of event always brings great risk to miners and causes serious interruptions in the process of rock excavation. In general, the possibility of roof fall hazard occurrence is directly related to the local geology, the presence of horizontal stresses as well as the type of excavation method and the efficacy of the utilized roof support. Due to the complexity of this process, it is important to continuously evaluate the roof fall risk, especially in long life-time places where a mining crew is often present. Within this article, a detailed review of the current methods of monitoring and evaluating roof fall risk was presented. Based on the extensive literature survey, different types of devices were described, and their advantages and disadvantages were pointed out. Furthermore, new trends in the area of roof fall risk monitoring were described and discussed.
A Composite Variable Structure PI Controller for Sensorless Speed Control Systems of IPMSM
Weidong Feng, Jing Bai, Zhiqiang Zhang, Jing Zhang
February 24, 2023 (v1)
Keywords: composite variable structure PI, improved MRAS, interior permanent magnet synchronous motor
In the speed control system of an Interior Permanent Magnet Synchronous Motor (IPMSM) without a speed sensor, PI controllers using only a fixed set of parameters cannot achieve accurate tracking of the estimated speed in a wide speed domain and also suffer from step response overshoot. This paper proposes a Compound Variable Structure PI (CVSPI) controller to improve the system control performance. It can choose whether to include an integral term according to the size of the system deviation to speed up the response. It also introduces a Model Reference Adaptive System (MRAS) speed observer in the controller to estimate the speed and adaptively adjust the size of the anti-integration saturation gain to improve the dynamic response following performance and immunity of the system. A feed-forward link is added for a given input differential to achieve an accurate answer to time-varying inputs. As the linear compensation matrix of the conventional MRAS is a unit matrix, the speed can onl... [more]
Enhancement of Heat Transfer in a Microchannel via Passive and Active Control of a Jet Issued from the Circular Cylinder
Zhiqiang Xin, Xiangyu Kong, Jing Chen
February 24, 2023 (v1)
Keywords: flow control, heat transfer, jet, microchannel, vorticity dynamic
The heat transfer enhancement of a jet issued from the circular cylinder placed in a three-dimensional microchannel at low Reynolds numbers were studied systematically by using the numerical simulation. The effects of the jet on thermal efficiency were evaluated by varying injection ratios (I) and jet angles (θ). The physical mechanism of heat transfer was revealed through the analyses of vorticity dynamic and temperature field. The results showed that the thermal efficiency was proportional to the injection ratio at Re = 100 and 200. However, at Re = 300, the thermal efficiency did not increase monotonically with the injection ratio, and the local maximum value of heat transfer efficiency, slightly less than the highest thermal efficiency, appeared at I = 1.5. This was a result of the jet inducing the vortex generated on the cylinder to become unstable. Furthermore, the change of jet angle had a better effect on heat transfer performance compared to the increase in the injection ratio... [more]
Creep Phenomenon in a Multiple-Input Single-Output Control System of a Piezoelectric Bimorph Actuator
Dariusz Grzybek, Andrzej Sioma
February 24, 2023 (v1)
Keywords: bimorph actuator, creep, macro fiber composite, MISO control system, piezoelectric actuator, piezoelectric composite, vision analysis
This article presents a comparison of the course of a creep phenomenon in the control system of a bimorph actuator, in which control voltages were applied to both piezoelectric layers, with the course of the creep phenomenon in the control system of a unimorph actuator, in which a control voltage was applied to only one piezoelectric layer. The bimorph actuator was built from two layers of piezoelectric composite, macro fiber composite was applied, and a carrier layer made of epoxy laminate was used for production of printed circuit boards. A comparative analysis was carried out on the basis of 22 laboratory experiments in which the vision system was used to measure a displacement change of six points of the bimorph actuator structure. Based on the results of laboratory experiments, it was noted that the duration of a transient part is approximately the same in a system with a control voltage applied to one MFC patch as in a system with control voltages applied to two MFC patches. In t... [more]
Numerical Study on Transverse Jet Mixing Enhanced by High Frequency Energy Deposition
Zilin Cai, Feng Gao, Hongyu Wang, Cenrui Ma, Thomas Yang
February 24, 2023 (v1)
Keywords: mixing enhancement, plasma flow control, pulsed energy deposition, transverse jet
Supersonic incoming flow has a large momentum, which makes it difficult for transverse jets to have a large penetration depth due to the strong compression of the incoming flow. This impacts the mixing efficiency of the jet in the supersonic combustor. This paper proposes a method to improve the mixing efficiency of a rectangular flow field model using pulsed energy deposition, which is verified numerically. In the simulations, the Navier−Stokes equations with an energy source are solved to simulate the effects of energy deposition with various distributions on the fuel mixture. The results show that the energy deposition increases the turbulent kinetic energy, which enlarges the scale of the flow vortex and improves the fuel mixing performance. The energy deposition is distributed upstream and significantly improves the mixing performance. Energy deposition can improve the penetration depth of fuel, which is more significant when the energy deposition is distributed downstream of the... [more]
Analytical Estimation of Power Losses in a Dual Active Bridge Converter Controlled with a Single-Phase Shift Switching Scheme
Marek Turzyński, Serafin Bachman, Marek Jasiński, Szymon Piasecki, Marek Ryłko, Huang-Jen Chiu, Shih-Hao Kuo, Yu-Chen Chang
February 24, 2023 (v1)
Keywords: analytical calculations, bidirectional isolated DAB, DC/DC converter, dual active bridge, efficiency, estimation, power loss, SiC MOSFET
Micro-grid solutions around the world rely on the operation of DC/DC power conversion systems. The most commonly used solution for these topologies is the use of a dual active bridge (DAB) converter. Increasing the efficiency and reliability of this system contributes to the improvement in the stability of the entire microgrid. This paper discussed an analytical method of energy efficiency and power loss estimation in a single phase dual active bridge (DAB) converter controlled with a single-phase shift (SPS) modulation scheme for microgrid system stability. The presented approach uses conduction and commutation losses of semiconductors and high frequency transformer. All parameters required for the calculation may be obtained from the manufacturers’ datasheets or can be based on a simple measurement. The approach was validated by the comparison of the estimated energy efficiency characteristics with the measured ones for a prototype of a 5 kW single phase DAB converter equipped with s... [more]
Investigation of the Effect of Rod Worth Uncertainty on the Reactivity Measurements of CEFR Start-Up Tests via McCARD Monte Carlo Calculations
Min Jae Lee, Jong-Hyuck Won, Jiwon Choe, Jae-Yong Lim
February 24, 2023 (v1)
Keywords: Chinese Experimental Fast Reactor (CEFR), control rod worth, McCARD, Monte Carlo, reactivity measurement, uncertainty
In the reactivity measurements of the China Experimental Fast Reactor (CEFR) start-up tests, five independent control rods were moved to compensate for the reactivity insertion. Since the recorded control rod positions were converted to reactivity via S-curves (rod worth curves), any uncertainty in the S-curves can propagate to all reactivity measurements. In this work, we rigorously derived the uncertainty of the reactivity in terms of the statistical uncertainty of the S-curves with Monte Carlo (MC) simulations. Additionally, the average error of the control rod worth from the MC calculation was estimated from experiments and embedded into the uncertainty formulation. The formulation shows that the error of the reactivity is highly correlated to the changes in the control rod position during the reactivity measurements. McCARD MC simulations were then conducted for the CEFR start-up tests, and the calculated reactivity and uncertainty were compared with the measurements. The main err... [more]
Study on the Influence and Control of Stress Direction Deflection and Partial-Stress Boosting of Main Roadways Surrounding Rock and under the Influence of Multi-Seam Mining
Dongdong Chen, Fangfang Guo, Zijian Li, Xiang Ma, Shengrong Xie, Yiyi Wu, Zhiqiang Wang
February 24, 2023 (v1)
Keywords: deflection of principal stress, ground control, main roadway group, mining-induced stress, surrounding rock stability
A large coal pillar (usually more than 90 m) is generally left in place to ensure the stability of main roadway groups, due to its long service lifespan, which commonly also causes a significant loss of coal resources. The design of the width of the protective coal pillar and the control system of the surrounding rock are directly determined by the characteristics of the stress field and the damage mechanism under the influence of the mining activities. However, there are few studies on the effects of the partial-stress boosting and the direction deflection of the stress field on the failure evolution of the surrounding rock (especially in multi-seam mining). In this paper, theoretical analysis and numerical simulation are used to investigate the direction evolution of the maximum principal stress in front of the working face with malposition distances between the upper and lower working faces during the influence of double coal seams mining. Furthermore, a large-scale numerical model... [more]
A New Optimal Thermal-Based Adaptive Frequency Control for Bidirectional DC−DC Converter with Full-Range ZVS
Lulin Zhang, Shu Cheng, Jingtao Xu, Chaoqun Xiang, Tianjian Yu
February 24, 2023 (v1)
Keywords: adaptive frequency control, bidirectional DC–DC converter, digital control, optimal temperature control, zero-voltage switching
A new, optimal thermal-based adaptive frequency control (OTC) for a bidirectional DC−DC converter with full-range zero-voltage switching (ZVS) is presented in this paper. The proposed OTC achieves ZVS for a bidirectional DC−DC converter without any zero-crossing detection (ZCD) circuit or current sensor. In order to ensure a ZVS over a wide voltage and load range, the optimal switching frequency was adjusted by detecting and tracking the lowest junction temperature of the semiconductor device. Because the proposed OTC does not need a ZCD circuit, the complexity of the circuit and the susceptibility of the sampling noise are reduced. Additionally, compared with the expensive current sensor, the proposed method of temperature detection by the NTC thermistor decreases the cost. In addition, the proposed OTC does not need accurate circuit parameters and voltage or current sampling results, so the dependence on the parameters is reduced. Moreover, the temperature of the switch is directly m... [more]
Novel Hydraulic and Aerodynamic Schemes of Coil Type Steam Generator: A Mathematical Model and Experimental Data
Sulpan Kuskarbekova, Konstantin Osintsev, Sergei Aliukov
February 24, 2023 (v1)
Keywords: aerodynamic system, automatic control system, controller, hydraulic system, Reynolds number, virtual desktop of the laboratory stand
Direct-flow steam boilers of the coil type are simple structures in which rather complex processes take place. To study this area, an educational laboratory stand was designed and constructed, which simulates the operation of a boiler of a similar design. In order to optimize the intensification of heat exchange processes in the device, raise its steam capacity, and improve its efficiency, the stand contains hydraulic and aerodynamic circuits for evaluating the movement of the coolant and air flows in the boiler. The proposed mathematical model gave an idea of the nature of the movement of the coolant in a curved pipe. The model takes into account the parameters of the screw channel for a more accurate result. The model can be used to predict the movement of the coolant in such coils with varying degrees of contamination. When designing a laboratory stand, the need for automated control is taken into account. The use of a controller to regulate the rotation speed of the pump motor made... [more]
PSO-Based Model Predictive Control for Load Frequency Regulation with Wind Turbines
Wei Fan, Zhijian Hu, Veerapandiyan Veerasamy
February 24, 2023 (v1)
Keywords: load frequency control, Model Predictive Control, Particle Swarm Optimization, wind turbines
With the high penetration of wind turbines, many issues need to be addressed in relation to load frequency control (LFC) to ensure the stable operation of power grids. The particle swarm optimization-based model predictive control (PSO-MPC) approach is presented to address this issue in the context of LFC with the participation of wind turbines. The classical MPC model was modified to incorporate the particle swarm optimization algorithm for the power generation model to regulate the system frequency. In addition to addressing the unpredictability of wind turbine generation, the presented PSO-MPC strategy not only addresses the randomness of wind turbine generation, but also reduces the computation burden of traditional MPC. The simulation results validate the effectiveness and feasibility of the PSO-MPC approach as compared with other state-of-the-art strategies.
Toward the Application of Pulse Width Modulated (PWM) Inverter Drive-Based Electric Propulsion to Ice Capable Ships
Eric Christopher Renz, James Turso
February 24, 2023 (v1)
Keywords: DQ control of propulsion motors, ice breaker, PWM inverter electric drive
The current world geopolitical state has driven significant interest in expanding influence in the polar regions. In order to develop new trade routes and defense of these areas, specialized ice-capable vessels are needed. Traditional propulsion technology utilized for these vessels has featured diesel and turbo electric drives with cycloconverter based technology used for speed regulation. Cycloconverter technology has the major disadvantage of characteristic output voltage waveforms that are very non-sinusoidal which induce harmonic rich currents with their resulting negative effects on total power factor and efficiency. There is also the potential to induce harmonic currents that may increase heat production in power cables, stressing insulation and reducing overall component life. Furthermore, sensitive loads such as control system power supplies may also be affected. The output waveform of a PWM drive has harmonic content that is both less severe, and more easily analyzed with cur... [more]
Minimizing Leakage Magnetic Field of Wireless Power Transfer Systems Using Phase Difference Control
Seongho Woo, Yujun Shin, Changmin Lee, Jaewon Rhee, Jangyong Ahn, Jungick Moon, Seokhyeon Son, Sanguk Lee, Hongseok Kim, Seungyoung Ahn
February 24, 2023 (v1)
Keywords: electromagnetic field (EMF), leakage magnetic field, shielding method, wireless power transfer (WPT)
In this paper, we propose a method to reduce the leakage magnetic field from wireless power transfer (WPT) systems with series−series compensation topology by adjusting the phase difference between the transmitter (TX) coil current and the receiver (RX) coil current without additional shielding coils or materials. A WPT system employing the proposed method adjusts the phase difference between the TX coil current and RX coil current by tuning a resonant capacitor of the RX coil. The conditions for minimizing the leakage magnetic field are derived, and the range of the resonant capacitor of RX, considering power transfer efficiency and the leakage magnetic field, is proposed. Through simulations and experiments, it is verified that the proposed method can reduce the leakage magnetic field level without any additional materials. For that reason, the proposed method can be suitable for size-limited, weight-limited or cost-limited WPT systems.
A Comparative Study of Fuzzy SMC with Adaptive Fuzzy PID for Sensorless Speed Control of Six-Phase Induction Motor
Lelisa Wogi, Tadele Ayana, Marcin Morawiec, Andrzej Jąderko
February 24, 2023 (v1)
Keywords: adaptive fuzzy PID, fuzzy sliding mode controller, sensorless speed control, six-phase squirrel cage induction motor, sliding mode controller, stability
Multi-phase motors have recently replaced three-phase induction motors in a variety of applications due to the numerous benefits they provide, and the absence of speed sensors promotes induction motors with variable speed drives. Sensorless speed control minimizes unnecessary speed encoder cost, reduces maintenance, and improves the motor drive’s reliability. The performance comparison of the fuzzy sliding mode controller (FSMC) with adaptive fuzzy proportional integral derivative (AFPID) control methods for sensorless speed control of six-phase induction motors was analyzed in this study, and the proposed control system has an advantage for multiphase machines, specifically six-phase induction motors (IMs) in this study, as they are the current active research area for electric vehicles, hybrid electric vehicles, aerospace, ship propulsion, and high-power applications. The speed control of a six-phase induction motor was performed by using an AFPID controller and FSMC. The comparative... [more]
Analysis of Characteristics of Low Voltage Circuit Breaker by External Magnetic Field
Young-Maan Cho, Hyun-Jong Park, Jae-Jun Lee, Kun-A Lee
February 24, 2023 (v1)
Keywords: dielectric recovery strength, external magnetic field, molded case circuit breaker, short-circuit characteristics
Recently, as interest in eco-friendly distributed power has increased, studies on the improvement of the performance of breakers such as DC breakers and on the reliability of existing AC breakers have been actively conducted. To improve the performance and reliability of these breakers, this paper conducted the analysis of characteristics of a low voltage circuit breaker using an external magnetic field. In this experiment, before the current-zero point, the cut-off time to improve the breaker performance is shortened and after the current-zero point, re-ignition, which is associated with reliability, is suppressed. According to the experimental results, the short-circuit characteristics before current-zero show a significant difference of 0.13 ms in the t21 section, and the dielectric recovery strength after current-zero shows a 13.3% performance improvement in the latter half of the DRV (dielectric recovery voltage) V-t curve. This result has significant meaning because it can be eas... [more]
Optimal Control of a PHEV Based on Backward-Looking Model Extended with Powertrain Transient Effects
Jure Soldo, Ivan Cvok, Joško Deur
February 24, 2023 (v1)
Keywords: backward-looking model, control, dynamic programming, plug-in hybrid electric vehicle, power flow management, shift control, transient phenomena
The paper proposes a power flow control strategy for a P2 parallel plug-in hybrid electric vehicle (PHEV) which takes into account torque and power losses related to engine-on and gear shift transients. An extended backward-looking (EXT-BWD) model is proposed to account for the transient losses, while the control strategy combines a rule-based controller with an equivalent consumption minimization strategy. To describe the transient losses, the EXT-BWD model includes additional state variables related to engine on/off flag and gear ratio in the previous time step. To establish a performance benchmark for control strategy verification, a dynamic programming-based control variable optimization framework is established based on the EXT-BWD model. The proposed control strategy is demonstrated to improve the fuel efficiency and drivability compared to the original control strategy while retaining comparable computational efficiency.
A Study of Thermoelectric Generation Coupled with Methanol Steam Reforming for Hydrogen Production
Guoqiang Wang, Feng Wang, Delun Guan
February 24, 2023 (v1)
Keywords: Energy Conversion, hydrogen energy, methanol steam reforming, thermal management and control, waste heat recovery
Waste heat recovery was considered as a promising candidate for energy conservation and emission reduction. Methanol steam reforming was considered to be an effective means for hydrogen production because of its advantages. In this work, a micro reactor was constructed and thermoelectric generation coupled with hydrogen production from methanol steam reforming was innovatively used to recycle waste heat, which was simulated by hot air from a hot air gun. The waste heat was converted into electricity and hydrogen at the same time. The characteristic of thermoelectric generation coupled with methanol steam reforming was investigated. It was experimentally verified that both the hydrogen production rate and methanol conversion increased with the increasing inlet temperature, but thermal efficiency increased firstly and then decreased with the increasing temperature. The methanol steam reforming could effectively maintain cold side temperature distribution of thermoelectric generation. In... [more]
Speed Control of Magnetic Drive-Trains with Pole-Slipping Amelioration
Xiaowen Liao, Chris Bingham, Tim Smith
February 24, 2023 (v1)
Keywords: dynamic analysis, magnetic drive-trains, pole-slipping detection, recovery, speed control
The paper introduces new techniques to reduce the potential for pole-slipping induced by control systems and presents a low-cost pole-slipping detection and recovery scheme for magnetic drive-trains (MDTs). For the first time, the paper shows that a combination of electromagnetic and load-torque excitations which individually are not greater than the maximum coupling torque can initiate pole-slipping. For applications where acceleration feedback is unavailable, the motor-side inertia is virtually increased with a tracking differentiator to provide feedback of acceleration. Subsequently, controller design and parameter optimization are discussed. Experimental measurements on a custom test facility verify the presented principles that low-bandwidth controller designs with low inertia ratios can accommodate a wider range of on-load startup torque and load-torque disturbances without pole-slipping. To address overload issues, a pole-slipping detection method based on the kurtosis of electr... [more]
Performance and Economic Analysis of the Multi-Energy Complementary Heating System under Different Control Strategies in Cold Regions
Xuebin Ma, Junfeng Li, Yucheng Ren, Reaihan E, Qiugang Wang, Jie Li, Sihui Huang, Mingguo Ma
February 24, 2023 (v1)
Keywords: control strategy, heating system, performance, solar energy
Multi-energy complementary heating (MECH) is the most promising and potential heating technology of the future. However, owing to the increase in energy types, the system is complex, and the operation procedure cumbersome. In addition, due to the uncertainty of climate conditions, it is difficult to develop a general control strategy suitable for all heating systems. In order to study the optimal control strategy of MECH systems with solar, biomass, and electric energy as three heat sources in cold regions, the system heating was tested over different periods during the entire heating season for rural residential buildings in cold regions, and the operating performance of the system was evaluated. The MECH experiment, based on the optimal control strategy, was compared with other different heating systems, and the economic and environmental benefits of the system were further evaluated. The results showed that, compared with room temperature control strategy (RS-CON), the control strat... [more]
Research on an Off-Chip Microvalve for Pneumatic Control in Microfluidic Chips
Xuling Liu, Wensi Zuo, Huafeng Song, Tingdong Shang, Haiwei Dong, Liangwen Wang, Jinggan Shao, Songjing Li
February 24, 2023 (v1)
Keywords: dynamic characteristics, mathematical model, mixing control, numerical simulation, PDMS three-way microvalve
A compact, rapid, and portable off-chip pneumatic control valve is significant for the miniaturization and integration of external pneumatic systems for microfluidic chips. In this work, an off-chip microvalve with a high-speed electromagnetic switch actuator and a polydimethylsiloxane (PDMS) material valve body has been designed to be easily encapsulated, simulated using MATLAB/Simulink software, and tested in a micromixer. Multi-physical coupling mathematical models are developed based on the elastic deformation force of the valve membrane, the driving force of the valve core, and the fluid force in the microchannel. Two single microvalves are used to form a three-way microvalve, which can control the air pressure in a pneumatic microchannel on the microfluidic chip. The relationship between the flow−duty cycle, the flow−pressure difference of the single electromagnetic microvalve, and the load pressure of the three-way microvalve is simulated and analyzed. Sample mixing performance... [more]
Hysteresis Based Quasi Fixed Frequency Current Control of Single Phase Full Bridge Grid Integrated Voltage Source Inverter
Lakshmi Syamala, Deepa Sankar, Suhara Ekkarakkudy Makkar, Bos Mathew Jos, Mathew Kallarackal
February 24, 2023 (v1)
Keywords: complex programmable logic device, constant switching frequency, grid integrated voltage source inverter, hysteresis current control
The traditional Fixed Band Hysteresis Current Control (FB-HCC) though being widely used for the current control of grid integrated voltage source inverter (GI-VSI), has the drawback of variable switching frequency. To overcome this drawback, Complex Programmable Logic Device (CPLD) based switching scheme is proposed in this paper. The proposed method calls for a single reference wave and the control concept is to terminate the rising and falling inductor current (iL) either by the comparator or by the CPLD, based on the nature of its slope. Termination of the iL with steeper slope by the comparator ensures lower current ripple, whereas the CPLD ensures constant switching frequency (fsw). However, the iL obtained with the proposed logic has a DC offset, which is corrected by modifying the reference. The basic concept, switching logic, and reference correction are thoroughly detailed. MATLAB/Simulink results are included to verify the proposed concept. The constant frequency operation of... [more]
Efficiency of a Twin-Two-Pump Hydraulic Power Pack with Pumps Equipped in Constant Pressure Regulators with Different Linear Performance Characteristics
Andrzej Banaszek, Radovan Petrović, Maja Andjelković, Milan Radosavljević
February 24, 2023 (v1)
Keywords: chemical tankers, constant pressure regulator with linear performance characteristics, efficiency, energy losses, hydraulic open system, hydraulic power pack, product tankers, twin-two-pump structure
The efficiency problem of hydraulic pump units with advanced double structures with constant pressure regulators with different linear characteristics in the case of work in an open supply system is presented in the paper. The main parts of the hydraulic power pack structure and pressure controller functions are described. The equation is given for the calculation of energy losses in particular pumps and the whole multi-pump power pack unit. The difference between the efficiency of particular pumps and the hydraulic pump unit was discussed.
Enhanced Retention and Synergistic Plugging Effect of Multi-Complexed Gel on Water-Swellable Rubber
Tong Li, Wenwu Yang, Jiajun Wu, Peidong Xing, Qian Xu, Hegao Liu, Guangsheng Cao
February 24, 2023 (v1)
Keywords: compound profile control agent system, high-permeability fractured channels, high-water cut reservoir, plugging mechanism
For the management of fractured large pores in high-water-bearing reservoirs, the general approach is to use transfer dissection and sealing. Conventional regulators have a limited regulating radius and can only produce blocking in the near-well zone, which is not ideal. Deep dissection technology can expand the radius of action and substantially improve the blocking effect. The existing deep-dissection agent system has problems such as high cost and poor effect, which affect its large-scale application. In this paper, to address these problems, a gel-type dissection modifier cross-linking agent was synthesized and optimized in the laboratory using low-concentration polymer, and the factors affecting the final gel formation effect were experimentally studied. The final polymer concentration was chosen to be 1500 mg/L~3000 mg/L, the poly-crossing ratio was 30:1, the pH was controlled at 7−9, and the temperature was controlled at 30−60 °C; the rubber was formed with good shear resistance... [more]
Deep Reinforcement Learning for the Optimal Angle Control of Tracking Bifacial Photovoltaic Systems
Shuto Tsuchida, Hirofumi Nonaka, Noboru Yamada
February 24, 2023 (v1)
Keywords: bifacial photovoltaic module, bifacial solar cell, deep reinforcement learning, tracking photovoltaic system
An optimal tilt-angle control based on artificial intelligence (AI control) for tracking bifacial photovoltaic (BPV) systems is developed in this study, and its effectiveness and characteristics are examined by simulating a virtual system over five years. Using deep reinforcement learning (deep RL), the algorithm autonomously learns the control strategy in real time from when the system starts to operate. Even with limited deep RL input variables, such as global horizontal irradiance, time, tilt angle, and power, the proposed AI control successfully learns and achieves a 4.0−9.2% higher electrical-energy yield in high-albedo cases (0.5 and 0.8) as compared to traditional sun-tracking control; however, the energy yield of AI control is slightly lower in low-albedo cases (0.2). AI control also demonstrates a superior performance when there are seasonal changes in albedo. Moreover, AI control is robust against long-term system degradation by manipulating the database used for reward setti... [more]
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