Aiming at the comparatively laggard level of power plant electrical system automation, this paper analyzes the feasibility,necessity and some key points of the application of integrated automation technology to power ...Aiming at the comparatively laggard level of power plant electrical system automation, this paper analyzes the feasibility,necessity and some key points of the application of integrated automation technology to power plant electrical system. New idea using fieldbus control system technology is presented. This paper also gives the outline and detailed schemes.展开更多
The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. Acc...The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed （iid） and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures （TBF） and time to repair （TTR） data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair （TTR） of this system varies in range 0.17-4 h with 1.002 h as mean time to repair （MTTR）. There is a 80% chance that the electrical system of shearer of Parvade. 1 mine repair will be accomplished within 1.45 h.展开更多
The core of computer numerical control(CNC) machine tool is the electrical system which controls and coordinates every part of CNC machine tool to complete processing tasks, so it is of great significance to strengthe...The core of computer numerical control(CNC) machine tool is the electrical system which controls and coordinates every part of CNC machine tool to complete processing tasks, so it is of great significance to strengthen the reliability of the electrical system. However, the electrical system is very complex due to many uncertain factors and dynamic stochastic characteristics when failure occurs. Therefore, the traditional fault tree analysis(FTA) method is not applicable. Bayesian network(BN) not only has a unique advantage to analyze nodes with multiply states in reliability analysis for complex systems, but also can solve the state explosion problem properly caused by Markov model when dealing with dynamic fault tree(DFT). In addition, the forward causal reasoning of BN can get the conditional probability distribution of the system under considering the uncertainty;the backward diagnosis reasoning of BN can recognize the weak links in system, so it is valuable for improving the system reliability.展开更多
Electrical system of military vehicle is a typical parameterized nonlinear system where complicated bifurcations may exist and threaten its safe and stable operation. An algebraic criterion for Hopf bifurcation is pre...Electrical system of military vehicle is a typical parameterized nonlinear system where complicated bifurcations may exist and threaten its safe and stable operation. An algebraic criterion for Hopf bifurcation is presented briefly and applied to find Hopf bifurcation point of the electrical system with automatic voltage regulator(AVR) dynamics in military vehicle. Hopf bifurcation controllers are designed for this electrical system by using wash-out filter,linear feedback,nonlinear feedback and their combination. The linear feedback control makes the system bring Hopf bifurcation at preferable parameter,the nonlinear feedback control modifies the type of the bifurcation,and the wash-out filter enhances the system damping,thus,the Hopf bifurcation is eliminated and the electrical system stability is ensured. Simulation results show the controller's validity.展开更多
Based on the integrated design and airworthiness verification of civil aircraft system,this paper completes the simulation modeling and fault modeling of aircraft electrical system. The aircraft electrical system is c...Based on the integrated design and airworthiness verification of civil aircraft system,this paper completes the simulation modeling and fault modeling of aircraft electrical system. The aircraft electrical system is constructed in the form of dual generators and dual-channel power supply. The main power supply adopts the three-stage power generation system,the auxiliary power supply system uses the permanent magnet synchronous power generation system and a battery. The transmission and distribution system is responsible for the electrical power conversion and the logic control in the system fault-pattern. The simulation results show that the system is reasonable and effective,which provides a reference for the optimal design and control of the actual aircraft electrical system.展开更多
In recent years, the level of science and technology has been changing with each passing day, especially the development and research in the field of artificial intelligence has become a hot topic of social concern. H...In recent years, the level of science and technology has been changing with each passing day, especially the development and research in the field of artificial intelligence has become a hot topic of social concern. However, due to the limitation of related technologies, artificial intelligence has not been widely promoted and applied in many industries. In this paper, the application of artificial intelligence technology is deeply analyzed from the perspective of electrical automation control, hoping to provide development ideas for the current electrical automation control in our country.展开更多
With large-scale use of kinds of motors, oilfield drilling electrical system always accompanied by serious power quality problem, including reactive current, harmonics current and grid voltage distortion, which would ...With large-scale use of kinds of motors, oilfield drilling electrical system always accompanied by serious power quality problem, including reactive current, harmonics current and grid voltage distortion, which would greatly threaten the safety and proper working of the whole system. This paper focuses on a power quality improvement project to solve these problems. A hybrid compensating scheme, including an active compensator and a passive compensator, is carried out. Because of the specificity of oilfield drilling electrical system, compensators are redesigned against features of this application background. And then the current detection point arrangement of this hybrid system is also taken into consideration to build the whole system much more effective and reliable. Now the improvement project is already implemented in application field, and the power quality of the system is greatly improved.展开更多
With the development of social economy and the acceleration of people's work and life rhythm, the rapid development of China's aviation industry has been strongly promoted. Air travel has become a convenient w...With the development of social economy and the acceleration of people's work and life rhythm, the rapid development of China's aviation industry has been strongly promoted. Air travel has become a convenient way for ordinary citizens to travel. In this case, people pay more attention to the safety of flight. As an important part of an airplane, the aviation electrical system carries many key missions in the flight and plays a very important role in the safe flight of the airplane. The management of the aviation electrical system is an important part of the aviation safety management. Aviation safety is related to the safety of people's lives and property, as well as the development of the aviation industry. Based on this, starting from the basic concept of aviation safe flight, this paper gives an overview of aviation power system, analyzes the factors affecting the safety of aviation power system, and expounds the importance of aviation electrical system to safe flight, hoping to provide effective reference for relevant personnel, so as to better promote the development of China's aviation industry.展开更多
Green energy conservation is the mainstream trend in the current development of the construction industry.The application of energy-saving technology in building electrical system design can effectively reduce energy ...Green energy conservation is the mainstream trend in the current development of the construction industry.The application of energy-saving technology in building electrical system design can effectively reduce energy consumption,avoid unnecessary energy consumption,and truly achieve energy conservation and environmental protection.Based on this,the article elaborates on the principles of energy-saving design in building electrical systems,and actively explores the application of energy-saving technologies from different perspectives such as optimizing power supply and distribution system design,adopting high-efficiency energy-saving lighting equipment,applying renewable energy,promoting smart home technology,and improving the efficiency of building electrical equipment.展开更多
The electrical system of WK-35 electric shovel 6SE70 is seriously aging, and the electrical failure of the fryer frequently occurs, resulting in repeated maintenance of the equipment, high labor intensity and high pro...The electrical system of WK-35 electric shovel 6SE70 is seriously aging, and the electrical failure of the fryer frequently occurs, resulting in repeated maintenance of the equipment, high labor intensity and high production cost. Chinas automation industry has experienced rapid development for many years, and the inverter has made great progress in product performance and appearance. The self-developed electric shovel electric control system can provide a complete set of solutions for 10m3 ~ 55m3 electric shovel AC telex system and related products, and completed the localization and digital transformation of electric shovels.展开更多
With the proposal of intelligent manufacturing concept, electrical automation is more and more widely used in mechanical manufacturing and special equipment. The electrical control system is mainly composed of three m...With the proposal of intelligent manufacturing concept, electrical automation is more and more widely used in mechanical manufacturing and special equipment. The electrical control system is mainly composed of three modules: input, logic and execution. It can not only display the current, temperature and other data during the operation of electrical equipment, but also realize intelligent control and maintain the safe operation of the whole equipment.We should analyze different types of electrical equipment, formulate maintenance plans according to their circuits, electronic component functions and computer control systems, regularly overhaul the equipment and control systems, and eliminate potential safety hazards in time;Use intelligent detection equipment to quickly detect the electrical control system, check the performance of current and electronic components, and replace damaged electronic components and components in time;Standardize the conventional detection method, check the wires, motors, electrical windings and transformers of electrical equipment, quickly locate the fault location and improve the maintenance efficiency;Actively learn the information detection technology, monitor the temperature, current and voltage of the electrical control system, and timely arrange maintenance personnel for troubleshooting in case of abnormal data, so as to ensure the safe and smooth operation of the electrical control system.展开更多
The Electrical Power System(EPS)is one of the spacecraft’s key subsystems,and its operational status directly affects the lifespan and performance of the entire spacecraft.The corresponding fault diagnosis has always...The Electrical Power System(EPS)is one of the spacecraft’s key subsystems,and its operational status directly affects the lifespan and performance of the entire spacecraft.The corresponding fault diagnosis has always been the discussion focus to ensure spacecraft reliability.In this paper,a few-shot unsupervised fault diagnosis method based on the improved Newman community division algorithm is proposed,to approach the scarcity of fault data samples and the inconspicuous characteristics of abnormal data.Firstly,aiming to capture the overall relevance of the fault dataset,a complex network model is built by adopting the K-Dynamic time warping distance Adjacent Nodes(KDAN)method.Based on the complex network model,the Newman community divisions algorithm is improved by using the Quantum-behaved Particle Swarm Optimization(QPSO).Subsequently,in order to evaluate the feasibility of the proposed method,experimental validation was conducted using an open-source dataset.The results indicate that the average accuracy can reach 96.43% for fault data diagnosis,and an F1_score of 97.76%with only 17.65%of the dataset used for training.The proposed method can accurately classify abnormal data by identifying the community structure in the data network,significantly improve the efficiency of the community divisions algorithm and reduce its complexity,and provide a new solution for fault diagnosis in large-scale complex systems.展开更多
The rapid development of wind energy in the power sectors raises the question about the reliability of wind turbines for power system planning and operation.The electrical subsystem of wind turbines(ESWT),which is one...The rapid development of wind energy in the power sectors raises the question about the reliability of wind turbines for power system planning and operation.The electrical subsystem of wind turbines(ESWT),which is one of the most vulnerable parts of the wind turbine,is investigated in this paper.The hygrothermal aging of power electronic devices(PEDs)is modeled for the first time in the comprehensive reliability evaluation of ESWT,by using a novel stationary“circuit-like”approach.First,the failure mechanism of the hygrothermal aging,which includes the solder layer fatigue damage and packaging material performance degradation,is explained.Then,a moisture diffusion resistance concept and a hygrothermal equivalent circuit are proposed to quantitate the hygrothermal aging behavior.A conditional probability function is developed to calculate the time-varying failure rate of PEDs.At last,the stochastic renewal process is simulated to evaluate the reliability for ESWT through the sequential Monte Carlo simulation,in which failure,repair,and replacement states of devices are all included.The effectiveness of our proposed reliability evaluation method is verified on an ESWT in a 2 MW wind turbine use time series data collected from a wind farm in China.展开更多
With the widespread application of combined heat and power(CHP)units,the economic dispatch of integrated electric and district heating systems(IEHSs)has drawn increasing attention.Because the electric power system(EPS...With the widespread application of combined heat and power(CHP)units,the economic dispatch of integrated electric and district heating systems(IEHSs)has drawn increasing attention.Because the electric power system(EPS)and district heating system(DHS)are generally managed separately,the decentralized dispatch pattern is preferable for the IEHS dispatch problem.However,many common decentralized methods suffer from the drawbacks of slow and local convergence.Moreover,the uncertainties of renewable generation cannot be ignored in a decentralized pattern.Additionally,the most commonly used individual chance constraints in distributionally robust optimization cannot consider safety constraints simultaneously,so the safe operation of an IEHS cannot be guaranteed.Thus,distributionally robust joint chance constraints and robust constraints are jointly introduced into the IEHS dispatch problem in this paper to obtain a stronger safety guarantee,and a method combined with Bonferroni and conditional value at risk(CVaR)approximation is presented to transform the original model into a quadratic program.Additionally,a dynamic boundary response(DBR)-based distributed algorithm based on multiparametric programming is proposed for a fast solution.Case studies showcase the necessity of using mixed distributionally robust joint chance constraints and robust constraints,as well as the effectiveness of the DBR algorithm.展开更多
Neuromuscular electrical stimulation(NMES)is a well-established therapeutic approach for chronic wounds.Conventionally,NMES involves direct electrode contact with wounds or adjacent healthy skin;however,it is limited ...Neuromuscular electrical stimulation(NMES)is a well-established therapeutic approach for chronic wounds.Conventionally,NMES involves direct electrode contact with wounds or adjacent healthy skin;however,it is limited by the need for wound exposure and by increased pain.Our preliminary study demonstrated the innovative application of remote NMES(rNMES)to the skeletal muscle of the distal calf,which showed the potential to accelerate wound healing in remote areas.rNMES was effective in human clinical trials in our previous work,although the underlying mechanisms remain unclear.As rNMES is often used to stimulate muscle contraction in long-term bedridden patients,we analyzed data from the Gene Expression Omnibus(GEO)database and found that exercise promotes midkine(MDK)expression in muscle.MDK is a small secreted heparin-binding protein that interacts with multiple cell surface receptors to promote growth.In the present study,we found that MDK significantly enhanced macrophage efferocytosis in a low-density lipoprotein receptor-related protein 1(LRP1)-dependent manner.Our findings demonstrate that rNMES upregulates MDK expression in skeletal muscles through the AMPK-ERK axis,facilitating its delivery to wounds through the circulatory system and promoting LRP1-mediated efferocytosis of apoptotic cells,thereby expediting wound healing.展开更多
BACKGROUND In pediatric and adolescent athletes,there is a lack of understanding about the impact of factors such as race on the structural or cardiovascular adaptations in response to exercise which may unnecessarily...BACKGROUND In pediatric and adolescent athletes,there is a lack of understanding about the impact of factors such as race on the structural or cardiovascular adaptations in response to exercise which may unnecessarily disqualify athletes from the competitive sport.We hypothesized that race has an impact on cardiac adaptions in non-adult athletes.AIM To explore the racial disparity in electrocardiographic(ECG)and echocardiographic(ECHO)parameters in healthy adolescent athletes.METHODS A comprehensive electronic systematic literature search using MEDLINE database was performed from inception to September 20,2024.Inclusion criteria included randomized or observational cohort studies that recruited adolescent competitive athletes in any sport discipline and compared between the Black and White races with an age range of 12-18 years.RESULTS Of 723 records that were identified by the literature search,seven studies(n=5036)were included.The mean age was 13.0-18.0 years old with male predominance.Black athletes had significantly longer PR interval[mean difference(MD)=17.49 millisecond,95% CI:11.70-23.29]and shorter QRS complex duration(MD=-7.35 millisecond,95% CI:-9.17 to-5.53)and corrected QT interval(MD=-4.95 millisecond,95% CI:-7.69 to-2.22)than the White athletes.Black athletes were approximately four times more likely to have first-degree atrioventricular(AV)block,inverted T wave,ST-segment elevation,and left atrium(LA)enlargement than their White counterparts.In terms of ECHO parameters,Black athletes had significantly greater septal wall thickness(MD=0.85 mm,95% CI:0.62-1.07),posterior wall thickness(MD=1.07 mm,95% CI:0.36-1.78),relative wall thickness(MD=0.03,95%CI:0.001-0.06),maximal wall thickness(MD=1.05 mm,95%CI:0.28-1.83),and LA diameter(MD=1.64 mm,95%CI:0.16-3.12).CONCLUSION Race has an impact on the ECG and ECHO parameters that reflect cardiac adaptations in adolescent athletes.Black athletes tend to have an increased prevalence of distinct ECG changes such as first-degree AV block and T-wave inversions compared with their White counterparts.Despite having thicker septal and posterior walls,the overall prevalence of left ventricular hypertrophy did not differ between the races.展开更多
Hydrochloric acid(HCl)extensively exists in deep underground projects,arising from the transportation of industrial raw materials or fracturing fluids of petroleum engineering.It results in corrosion,which can signifi...Hydrochloric acid(HCl)extensively exists in deep underground projects,arising from the transportation of industrial raw materials or fracturing fluids of petroleum engineering.It results in corrosion,which can significantly impact the stability of surrounding rock structures.Therefore,in-depth analysis of the degradation of rock corroded by the HCl solution is an essential task for underground engineering.In this study,the granite specimens are initially treated with the HCl solution with various concentrations.Then,the tests and analyses,such as electrical conductivity(EC)measurements,mineral composition assays,and Brazilian splitting tests,are employed to investigate the corrosion mechanism of the HCl solution.Our results and findings are generally as follows:(1)As the immersion time increases,the EC exhibits a relatively high level at pH value of 1,a decreasing trend at pH value of 3,and an increasing trend at pH value of 5 and 7.(2)The HCl solutions with various concentration have different effect on mineral composition,characterized by an increase in proportion of SiO_(2) and a reduction in proportion of Na_(2)O,Al_(2)O_(3),K_(2)O,MgO,and CaO,as the solution pH value decreases.(3)After immersion in the solutions with pH values of 1,3,and 5,the tensile strength of the granite decreases by 23.85%,20.84%,and 20.24%;the average stiffness of the specimen decreases by 29.29%,23.43%,and 11.97%;the proportion of releasable energy increases by 6%,4%,and -2%;the releasable energy decreases by 54.96%,26.09%,and 14.52%;and the dissipated energy decreases by approximately 68.85%,41.39%,and 5.41%,respectively.(4)The evolution of physical and mechanical properties of the immersed granite specimen can be analyzed from a chemical aspect.The corrosive action of HCl cleaves Si–O and Al–O chemical bonds within the granite,particularly altering the tetrahedral structures of its silicate components.This process involves breaking existing chemical bonds and the formation of new ones,ultimately destroying the silicate molecular structures.As the concentration of HCl increases,the rate of these reactions accelerates,progressively weakening the chemical bonds and consequently deteriorating the mechanical characteristics of the granite.These findings can deepen our knowledge about the corrosion effect of HCI solutions on natural surrounding rocks and serve as references for further research on rock corrosion mechanisms in underground engineering.展开更多
Although previous studies have demonstrated that transcranial focused ultrasound stimulation protects the ischemic brain,clear criteria for the stimulation time window and intensity are lacking.Electrical impedance to...Although previous studies have demonstrated that transcranial focused ultrasound stimulation protects the ischemic brain,clear criteria for the stimulation time window and intensity are lacking.Electrical impedance tomography enables real-time monitoring of changes in cerebral blood perfusion within the ischemic brain,but investigating the feasibility of using this method to assess post-stroke rehabilitation in vivo remains critical.In this study,ischemic stroke was induced in rats through middle cerebral artery occlusion surgery.Transcranial focused ultrasound stimulation was used to treat the rat model of ischemia,and electrical impedance tomography was used to measure impedance during both the acute stage of ischemia and the rehabilitation stage following the stimulation.Electrical impedance tomography results indicated that cerebral impedance increased after the onset of ischemia and decreased following transcranial focused ultrasound stimulation.Furthermore,the stimulation promoted motor function recovery,reduced cerebral infarction volume in the rat model of ischemic stroke,and induced the expression of brain-derived neurotrophic factor in the ischemic brain.Our results also revealed a significant correlation between the impedance of the ischemic brain post-intervention and improvements in behavioral scores and infarct volume.This study shows that daily administration of transcranial focused ultrasound stimulation for 20 minutes to the ischemic hemisphere 24 hours after cerebral ischemia enhanced motor recovery in a rat model of ischemia.Additionally,our findings indicate that electrical impedance tomography can serve as a valuable tool for quantitatively evaluating rehabilitation after ischemic stroke in vivo.These findings suggest the feasibility of using impedance data collected via electrical impedance tomography to clinically assess the effects of rehabilitatory interventions for patients with ischemic stroke.展开更多
Conducting hydrogels have garnered significant interest in the field of wearable electronics.However,simultaneously achieving high transparency,high conductivity,strong adhesion,and self-healing ability within a short...Conducting hydrogels have garnered significant interest in the field of wearable electronics.However,simultaneously achieving high transparency,high conductivity,strong adhesion,and self-healing ability within a short time remains a major challenge.In this study,a multifunctional mussel-inspired hydrogel was synthesized in only 5 min,with polydopamine(PDA)-polypyrrole(Ppy)-polyaniline(PANi)and poly(vinyl alcohol)(PVA)nanoparticles incorporated into the polyacrylamide(PAM)network.The resulting hydrogel exhibited high transparency(about 90% light transmission in the range of 400-800 nm),high conductivity((95.4±0.4)×10^(-4)S/cm),tensile strength(32.60±1.03 k Pa),strain at break(904.46%±11.50%),and adhesive strength(30-60 k Pa).It also demonstrated rapid self-healing properties(about 48% strength recovery within 1h at 50℃)and water-dependent shape memory behavior.As a wearable strain sensor,the hydrogel successfully detected finger flexion,wrist movements,facial expression changes,and breathing with high sensitivity and stability.The calculated gauge factor(GF)was 7.44±0.31,which is higher than that of many previously reported hydrogels.Compared with previous oyster-inspired or Ppy-based hydrogels,our system showed a much shorter synthesis time,higher transparency,and enhanced multifunctionality.These findings highlight the potential of the proposed hydrogel for next-generation flexible electronics,e-skin,and biomedical monitoring devices.展开更多
To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electric...To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electrical current and high-temperature exposure is investigated.Isothermal thermogravimetric analysis was employed to quantify oxidation kinetics,complemented by microstructural characterization using X-ray diffraction,scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy.Experimental results demonstrate that the applied current dramatically enhances oxidation rates,increasing specific mass gain from 0.25 mg/cm^(2)(0 A/cm^(2))to 5.20 mg/cm^(2)(0.2 A/cm^(2))and oxide scale thickness from 1.87 to 15.62μm after 200 h.This acceleration originates from current-induced electromigration forces that promote cationic transport through the oxide layer.The quantitative relationships between current density and oxidation parameters are established,enabling predictive modeling of interconnector degradation in solid oxide fuel cell(SOFC)systems.展开更多
文摘Aiming at the comparatively laggard level of power plant electrical system automation, this paper analyzes the feasibility,necessity and some key points of the application of integrated automation technology to power plant electrical system. New idea using fieldbus control system technology is presented. This paper also gives the outline and detailed schemes.
文摘The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed （iid） and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures （TBF） and time to repair （TTR） data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair （TTR） of this system varies in range 0.17-4 h with 1.002 h as mean time to repair （MTTR）. There is a 80% chance that the electrical system of shearer of Parvade. 1 mine repair will be accomplished within 1.45 h.
基金the National Science and Technology Major Project of China(No.2014ZX04014-011)
文摘The core of computer numerical control(CNC) machine tool is the electrical system which controls and coordinates every part of CNC machine tool to complete processing tasks, so it is of great significance to strengthen the reliability of the electrical system. However, the electrical system is very complex due to many uncertain factors and dynamic stochastic characteristics when failure occurs. Therefore, the traditional fault tree analysis(FTA) method is not applicable. Bayesian network(BN) not only has a unique advantage to analyze nodes with multiply states in reliability analysis for complex systems, but also can solve the state explosion problem properly caused by Markov model when dealing with dynamic fault tree(DFT). In addition, the forward causal reasoning of BN can get the conditional probability distribution of the system under considering the uncertainty;the backward diagnosis reasoning of BN can recognize the weak links in system, so it is valuable for improving the system reliability.
基金Sponsored by Foundation for Science Research Development of Nanjing University of Science and Technology
文摘Electrical system of military vehicle is a typical parameterized nonlinear system where complicated bifurcations may exist and threaten its safe and stable operation. An algebraic criterion for Hopf bifurcation is presented briefly and applied to find Hopf bifurcation point of the electrical system with automatic voltage regulator(AVR) dynamics in military vehicle. Hopf bifurcation controllers are designed for this electrical system by using wash-out filter,linear feedback,nonlinear feedback and their combination. The linear feedback control makes the system bring Hopf bifurcation at preferable parameter,the nonlinear feedback control modifies the type of the bifurcation,and the wash-out filter enhances the system damping,thus,the Hopf bifurcation is eliminated and the electrical system stability is ensured. Simulation results show the controller's validity.
基金supported by the Key Research and Development Program of Shaanxi Province(2018GY-185)
文摘Based on the integrated design and airworthiness verification of civil aircraft system,this paper completes the simulation modeling and fault modeling of aircraft electrical system. The aircraft electrical system is constructed in the form of dual generators and dual-channel power supply. The main power supply adopts the three-stage power generation system,the auxiliary power supply system uses the permanent magnet synchronous power generation system and a battery. The transmission and distribution system is responsible for the electrical power conversion and the logic control in the system fault-pattern. The simulation results show that the system is reasonable and effective,which provides a reference for the optimal design and control of the actual aircraft electrical system.
文摘In recent years, the level of science and technology has been changing with each passing day, especially the development and research in the field of artificial intelligence has become a hot topic of social concern. However, due to the limitation of related technologies, artificial intelligence has not been widely promoted and applied in many industries. In this paper, the application of artificial intelligence technology is deeply analyzed from the perspective of electrical automation control, hoping to provide development ideas for the current electrical automation control in our country.
文摘With large-scale use of kinds of motors, oilfield drilling electrical system always accompanied by serious power quality problem, including reactive current, harmonics current and grid voltage distortion, which would greatly threaten the safety and proper working of the whole system. This paper focuses on a power quality improvement project to solve these problems. A hybrid compensating scheme, including an active compensator and a passive compensator, is carried out. Because of the specificity of oilfield drilling electrical system, compensators are redesigned against features of this application background. And then the current detection point arrangement of this hybrid system is also taken into consideration to build the whole system much more effective and reliable. Now the improvement project is already implemented in application field, and the power quality of the system is greatly improved.
文摘With the development of social economy and the acceleration of people's work and life rhythm, the rapid development of China's aviation industry has been strongly promoted. Air travel has become a convenient way for ordinary citizens to travel. In this case, people pay more attention to the safety of flight. As an important part of an airplane, the aviation electrical system carries many key missions in the flight and plays a very important role in the safe flight of the airplane. The management of the aviation electrical system is an important part of the aviation safety management. Aviation safety is related to the safety of people's lives and property, as well as the development of the aviation industry. Based on this, starting from the basic concept of aviation safe flight, this paper gives an overview of aviation power system, analyzes the factors affecting the safety of aviation power system, and expounds the importance of aviation electrical system to safe flight, hoping to provide effective reference for relevant personnel, so as to better promote the development of China's aviation industry.
文摘Green energy conservation is the mainstream trend in the current development of the construction industry.The application of energy-saving technology in building electrical system design can effectively reduce energy consumption,avoid unnecessary energy consumption,and truly achieve energy conservation and environmental protection.Based on this,the article elaborates on the principles of energy-saving design in building electrical systems,and actively explores the application of energy-saving technologies from different perspectives such as optimizing power supply and distribution system design,adopting high-efficiency energy-saving lighting equipment,applying renewable energy,promoting smart home technology,and improving the efficiency of building electrical equipment.
文摘The electrical system of WK-35 electric shovel 6SE70 is seriously aging, and the electrical failure of the fryer frequently occurs, resulting in repeated maintenance of the equipment, high labor intensity and high production cost. Chinas automation industry has experienced rapid development for many years, and the inverter has made great progress in product performance and appearance. The self-developed electric shovel electric control system can provide a complete set of solutions for 10m3 ~ 55m3 electric shovel AC telex system and related products, and completed the localization and digital transformation of electric shovels.
文摘With the proposal of intelligent manufacturing concept, electrical automation is more and more widely used in mechanical manufacturing and special equipment. The electrical control system is mainly composed of three modules: input, logic and execution. It can not only display the current, temperature and other data during the operation of electrical equipment, but also realize intelligent control and maintain the safe operation of the whole equipment.We should analyze different types of electrical equipment, formulate maintenance plans according to their circuits, electronic component functions and computer control systems, regularly overhaul the equipment and control systems, and eliminate potential safety hazards in time;Use intelligent detection equipment to quickly detect the electrical control system, check the performance of current and electronic components, and replace damaged electronic components and components in time;Standardize the conventional detection method, check the wires, motors, electrical windings and transformers of electrical equipment, quickly locate the fault location and improve the maintenance efficiency;Actively learn the information detection technology, monitor the temperature, current and voltage of the electrical control system, and timely arrange maintenance personnel for troubleshooting in case of abnormal data, so as to ensure the safe and smooth operation of the electrical control system.
基金supported in part by the Natural Science Foundation of Shanghai,China(No.23ZR1432400)the Shanghai Pilot Program for Basic Research-Chinese Academy of Science(No.JCYJ-SHFY-2022-015).
文摘The Electrical Power System(EPS)is one of the spacecraft’s key subsystems,and its operational status directly affects the lifespan and performance of the entire spacecraft.The corresponding fault diagnosis has always been the discussion focus to ensure spacecraft reliability.In this paper,a few-shot unsupervised fault diagnosis method based on the improved Newman community division algorithm is proposed,to approach the scarcity of fault data samples and the inconspicuous characteristics of abnormal data.Firstly,aiming to capture the overall relevance of the fault dataset,a complex network model is built by adopting the K-Dynamic time warping distance Adjacent Nodes(KDAN)method.Based on the complex network model,the Newman community divisions algorithm is improved by using the Quantum-behaved Particle Swarm Optimization(QPSO).Subsequently,in order to evaluate the feasibility of the proposed method,experimental validation was conducted using an open-source dataset.The results indicate that the average accuracy can reach 96.43% for fault data diagnosis,and an F1_score of 97.76%with only 17.65%of the dataset used for training.The proposed method can accurately classify abnormal data by identifying the community structure in the data network,significantly improve the efficiency of the community divisions algorithm and reduce its complexity,and provide a new solution for fault diagnosis in large-scale complex systems.
基金supported by the National Natural Science Foundation of China under Grant 52022016China Postdoctoral Science Foundation under grant 2021M693711Fundamental Research Funds for the Central Universities under grant 2021CDJQY-037.
文摘The rapid development of wind energy in the power sectors raises the question about the reliability of wind turbines for power system planning and operation.The electrical subsystem of wind turbines(ESWT),which is one of the most vulnerable parts of the wind turbine,is investigated in this paper.The hygrothermal aging of power electronic devices(PEDs)is modeled for the first time in the comprehensive reliability evaluation of ESWT,by using a novel stationary“circuit-like”approach.First,the failure mechanism of the hygrothermal aging,which includes the solder layer fatigue damage and packaging material performance degradation,is explained.Then,a moisture diffusion resistance concept and a hygrothermal equivalent circuit are proposed to quantitate the hygrothermal aging behavior.A conditional probability function is developed to calculate the time-varying failure rate of PEDs.At last,the stochastic renewal process is simulated to evaluate the reliability for ESWT through the sequential Monte Carlo simulation,in which failure,repair,and replacement states of devices are all included.The effectiveness of our proposed reliability evaluation method is verified on an ESWT in a 2 MW wind turbine use time series data collected from a wind farm in China.
基金supported by National Natural Science Foundation of China(52377107,52007105)and the Taishan Scholars Program.
文摘With the widespread application of combined heat and power(CHP)units,the economic dispatch of integrated electric and district heating systems(IEHSs)has drawn increasing attention.Because the electric power system(EPS)and district heating system(DHS)are generally managed separately,the decentralized dispatch pattern is preferable for the IEHS dispatch problem.However,many common decentralized methods suffer from the drawbacks of slow and local convergence.Moreover,the uncertainties of renewable generation cannot be ignored in a decentralized pattern.Additionally,the most commonly used individual chance constraints in distributionally robust optimization cannot consider safety constraints simultaneously,so the safe operation of an IEHS cannot be guaranteed.Thus,distributionally robust joint chance constraints and robust constraints are jointly introduced into the IEHS dispatch problem in this paper to obtain a stronger safety guarantee,and a method combined with Bonferroni and conditional value at risk(CVaR)approximation is presented to transform the original model into a quadratic program.Additionally,a dynamic boundary response(DBR)-based distributed algorithm based on multiparametric programming is proposed for a fast solution.Case studies showcase the necessity of using mixed distributionally robust joint chance constraints and robust constraints,as well as the effectiveness of the DBR algorithm.
基金supported by the National Natural Science Foundation of China(Grant No.82271252 to W.L.,No.8217091029 to T.W.and No.82204542 to L.H.)the Key Medical Research Projects of Jiangsu Health and Health Commission(Grant No.K2023066 to L.Z.)the Taishan Industrial Talent Project(Grant No.2020-371722-73-03-097290 to W.L.).
文摘Neuromuscular electrical stimulation(NMES)is a well-established therapeutic approach for chronic wounds.Conventionally,NMES involves direct electrode contact with wounds or adjacent healthy skin;however,it is limited by the need for wound exposure and by increased pain.Our preliminary study demonstrated the innovative application of remote NMES(rNMES)to the skeletal muscle of the distal calf,which showed the potential to accelerate wound healing in remote areas.rNMES was effective in human clinical trials in our previous work,although the underlying mechanisms remain unclear.As rNMES is often used to stimulate muscle contraction in long-term bedridden patients,we analyzed data from the Gene Expression Omnibus(GEO)database and found that exercise promotes midkine(MDK)expression in muscle.MDK is a small secreted heparin-binding protein that interacts with multiple cell surface receptors to promote growth.In the present study,we found that MDK significantly enhanced macrophage efferocytosis in a low-density lipoprotein receptor-related protein 1(LRP1)-dependent manner.Our findings demonstrate that rNMES upregulates MDK expression in skeletal muscles through the AMPK-ERK axis,facilitating its delivery to wounds through the circulatory system and promoting LRP1-mediated efferocytosis of apoptotic cells,thereby expediting wound healing.
文摘BACKGROUND In pediatric and adolescent athletes,there is a lack of understanding about the impact of factors such as race on the structural or cardiovascular adaptations in response to exercise which may unnecessarily disqualify athletes from the competitive sport.We hypothesized that race has an impact on cardiac adaptions in non-adult athletes.AIM To explore the racial disparity in electrocardiographic(ECG)and echocardiographic(ECHO)parameters in healthy adolescent athletes.METHODS A comprehensive electronic systematic literature search using MEDLINE database was performed from inception to September 20,2024.Inclusion criteria included randomized or observational cohort studies that recruited adolescent competitive athletes in any sport discipline and compared between the Black and White races with an age range of 12-18 years.RESULTS Of 723 records that were identified by the literature search,seven studies(n=5036)were included.The mean age was 13.0-18.0 years old with male predominance.Black athletes had significantly longer PR interval[mean difference(MD)=17.49 millisecond,95% CI:11.70-23.29]and shorter QRS complex duration(MD=-7.35 millisecond,95% CI:-9.17 to-5.53)and corrected QT interval(MD=-4.95 millisecond,95% CI:-7.69 to-2.22)than the White athletes.Black athletes were approximately four times more likely to have first-degree atrioventricular(AV)block,inverted T wave,ST-segment elevation,and left atrium(LA)enlargement than their White counterparts.In terms of ECHO parameters,Black athletes had significantly greater septal wall thickness(MD=0.85 mm,95% CI:0.62-1.07),posterior wall thickness(MD=1.07 mm,95% CI:0.36-1.78),relative wall thickness(MD=0.03,95%CI:0.001-0.06),maximal wall thickness(MD=1.05 mm,95%CI:0.28-1.83),and LA diameter(MD=1.64 mm,95%CI:0.16-3.12).CONCLUSION Race has an impact on the ECG and ECHO parameters that reflect cardiac adaptations in adolescent athletes.Black athletes tend to have an increased prevalence of distinct ECG changes such as first-degree AV block and T-wave inversions compared with their White counterparts.Despite having thicker septal and posterior walls,the overall prevalence of left ventricular hypertrophy did not differ between the races.
基金National Science Fund for Distinguished Young Scholars,Grant/Award Number:52225403State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,Grant/Award Number:SDGZK2404Fundamental Research Funds for the Central Universities,Grant/Award Number:2023KYJD1006。
文摘Hydrochloric acid(HCl)extensively exists in deep underground projects,arising from the transportation of industrial raw materials or fracturing fluids of petroleum engineering.It results in corrosion,which can significantly impact the stability of surrounding rock structures.Therefore,in-depth analysis of the degradation of rock corroded by the HCl solution is an essential task for underground engineering.In this study,the granite specimens are initially treated with the HCl solution with various concentrations.Then,the tests and analyses,such as electrical conductivity(EC)measurements,mineral composition assays,and Brazilian splitting tests,are employed to investigate the corrosion mechanism of the HCl solution.Our results and findings are generally as follows:(1)As the immersion time increases,the EC exhibits a relatively high level at pH value of 1,a decreasing trend at pH value of 3,and an increasing trend at pH value of 5 and 7.(2)The HCl solutions with various concentration have different effect on mineral composition,characterized by an increase in proportion of SiO_(2) and a reduction in proportion of Na_(2)O,Al_(2)O_(3),K_(2)O,MgO,and CaO,as the solution pH value decreases.(3)After immersion in the solutions with pH values of 1,3,and 5,the tensile strength of the granite decreases by 23.85%,20.84%,and 20.24%;the average stiffness of the specimen decreases by 29.29%,23.43%,and 11.97%;the proportion of releasable energy increases by 6%,4%,and -2%;the releasable energy decreases by 54.96%,26.09%,and 14.52%;and the dissipated energy decreases by approximately 68.85%,41.39%,and 5.41%,respectively.(4)The evolution of physical and mechanical properties of the immersed granite specimen can be analyzed from a chemical aspect.The corrosive action of HCl cleaves Si–O and Al–O chemical bonds within the granite,particularly altering the tetrahedral structures of its silicate components.This process involves breaking existing chemical bonds and the formation of new ones,ultimately destroying the silicate molecular structures.As the concentration of HCl increases,the rate of these reactions accelerates,progressively weakening the chemical bonds and consequently deteriorating the mechanical characteristics of the granite.These findings can deepen our knowledge about the corrosion effect of HCI solutions on natural surrounding rocks and serve as references for further research on rock corrosion mechanisms in underground engineering.
基金supported by the Fundamental Research Funds for the Central Universities,Nos.G2021KY05107,G2021KY05101the National Natural Science Foundation of China,Nos.32071316,32211530049+1 种基金the Natural Science Foundation of Shaanxi Province,No.2022-JM482the Education and Teaching Reform Funds for the Central Universities,No.23GZ230102(all to LL and HH).
文摘Although previous studies have demonstrated that transcranial focused ultrasound stimulation protects the ischemic brain,clear criteria for the stimulation time window and intensity are lacking.Electrical impedance tomography enables real-time monitoring of changes in cerebral blood perfusion within the ischemic brain,but investigating the feasibility of using this method to assess post-stroke rehabilitation in vivo remains critical.In this study,ischemic stroke was induced in rats through middle cerebral artery occlusion surgery.Transcranial focused ultrasound stimulation was used to treat the rat model of ischemia,and electrical impedance tomography was used to measure impedance during both the acute stage of ischemia and the rehabilitation stage following the stimulation.Electrical impedance tomography results indicated that cerebral impedance increased after the onset of ischemia and decreased following transcranial focused ultrasound stimulation.Furthermore,the stimulation promoted motor function recovery,reduced cerebral infarction volume in the rat model of ischemic stroke,and induced the expression of brain-derived neurotrophic factor in the ischemic brain.Our results also revealed a significant correlation between the impedance of the ischemic brain post-intervention and improvements in behavioral scores and infarct volume.This study shows that daily administration of transcranial focused ultrasound stimulation for 20 minutes to the ischemic hemisphere 24 hours after cerebral ischemia enhanced motor recovery in a rat model of ischemia.Additionally,our findings indicate that electrical impedance tomography can serve as a valuable tool for quantitatively evaluating rehabilitation after ischemic stroke in vivo.These findings suggest the feasibility of using impedance data collected via electrical impedance tomography to clinically assess the effects of rehabilitatory interventions for patients with ischemic stroke.
文摘Conducting hydrogels have garnered significant interest in the field of wearable electronics.However,simultaneously achieving high transparency,high conductivity,strong adhesion,and self-healing ability within a short time remains a major challenge.In this study,a multifunctional mussel-inspired hydrogel was synthesized in only 5 min,with polydopamine(PDA)-polypyrrole(Ppy)-polyaniline(PANi)and poly(vinyl alcohol)(PVA)nanoparticles incorporated into the polyacrylamide(PAM)network.The resulting hydrogel exhibited high transparency(about 90% light transmission in the range of 400-800 nm),high conductivity((95.4±0.4)×10^(-4)S/cm),tensile strength(32.60±1.03 k Pa),strain at break(904.46%±11.50%),and adhesive strength(30-60 k Pa).It also demonstrated rapid self-healing properties(about 48% strength recovery within 1h at 50℃)and water-dependent shape memory behavior.As a wearable strain sensor,the hydrogel successfully detected finger flexion,wrist movements,facial expression changes,and breathing with high sensitivity and stability.The calculated gauge factor(GF)was 7.44±0.31,which is higher than that of many previously reported hydrogels.Compared with previous oyster-inspired or Ppy-based hydrogels,our system showed a much shorter synthesis time,higher transparency,and enhanced multifunctionality.These findings highlight the potential of the proposed hydrogel for next-generation flexible electronics,e-skin,and biomedical monitoring devices.
基金supported by Natural Science Foundation of Wuhan(2024040701010051)Natural Science Foundation of Hubei(2023AFB111)and National Natural Science Foundation of China(52401108).
文摘To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electrical current and high-temperature exposure is investigated.Isothermal thermogravimetric analysis was employed to quantify oxidation kinetics,complemented by microstructural characterization using X-ray diffraction,scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy.Experimental results demonstrate that the applied current dramatically enhances oxidation rates,increasing specific mass gain from 0.25 mg/cm^(2)(0 A/cm^(2))to 5.20 mg/cm^(2)(0.2 A/cm^(2))and oxide scale thickness from 1.87 to 15.62μm after 200 h.This acceleration originates from current-induced electromigration forces that promote cationic transport through the oxide layer.The quantitative relationships between current density and oxidation parameters are established,enabling predictive modeling of interconnector degradation in solid oxide fuel cell(SOFC)systems.
