With the continuous increase of aeroengine flight ceiling(>20 km),the thin atmosphere at high altitudes and the size effect all cause the compressor component inlet Reynolds number to decrease rapidly to a critical...With the continuous increase of aeroengine flight ceiling(>20 km),the thin atmosphere at high altitudes and the size effect all cause the compressor component inlet Reynolds number to decrease rapidly to a critical value(approximately 2.0×10^(5)),and the significant transition process on the blade/endwall surface leads to the sharp degradation of compressor performance,which seriously affects the engine fuel consumption and working stability at high altitudes.In this paper,the research progress on the internal flow mechanism and flow control methods of axial compressors at low Reynolds numbers is reviewed from the aspects of quantification and prediction of performance variation,flow loss mechanism related to separation and transition,efficient transition control and flow field organization.The development trend of the low-Reynolds-number effect of axial flow compressors is noted,and the difficulties and application prospects of aerodynamic design and efficient flow control methods for compressors under low Reynolds numbers at high altitudes are discussed.展开更多
First at all, it introduced the concept and the damages of continuous cropping obstacle. Then, it analyzed the causes of continuous cropping obstacles for Atractylodes macrocephala Koidz. In the end, in order to provi...First at all, it introduced the concept and the damages of continuous cropping obstacle. Then, it analyzed the causes of continuous cropping obstacles for Atractylodes macrocephala Koidz. In the end, in order to provide guidance for pro- moting sustainable development of Atractylodes macrocephala Koidz industry in Pingjiang County, it put forward some control methods for eliminating continuous cropping obstacles of Atractylodes macrocephala Koidz, including breeding varieties with high resistance; applying rotation cropping and intercropping reasonable; rational fertilization and soil disinfection; introducing antagonistic bacterial and eliminating au- tointoxication.展开更多
Based on the dynamics of ABS-equipped vehicles during cornering braking, the electronic brake- force distribution （EBD） control methods of ABS-equipped vehicles during cornering braking are proposed. According to th...Based on the dynamics of ABS-equipped vehicles during cornering braking, the electronic brake- force distribution （EBD） control methods of ABS-equipped vehicles during cornering braking are proposed. According to the dynamics and the tire model under tire adhesion limit, the stability acceptance criteria of vehicles during cornering braking are proposed. According to the stability acceptance criteria and the ABS control, the EBD control methods of ABS-equipped vehicles during cornering braking are implemented by adjusting the threshold values of tires slip independently. The vehicle states during cornering braking at two typical initial velocities of the vehicle are analyzed by the EBD control methods, whose results indicate the EBD control methods can improve the braking performances of the vehicle during cornering braking comparing with the ABS control.展开更多
Undoubtedly,noise has become a major hazardous issue in today’s industrial world,with a lot of people suffering from exposure to excessive noise in their work environments.This study was conducted to weigh and priori...Undoubtedly,noise has become a major hazardous issue in today’s industrial world,with a lot of people suffering from exposure to excessive noise in their work environments.This study was conducted to weigh and prioritize noise control methods in an Iranian tire manufacturing complex in Iran.The Delphi method and the Technique for Order Preference by Similarity and an Ideal Solution(TOPSIS)were utilized for this purpose.This cross-sectional,descriptive study was conducted in the baking hall of an Iranian tire manufacturing factory in 2016.To weigh and prioritize noise control methods,Analytic Hierarchy Process(AHP)and TOPSIS were applied.In total,4 criteria and 8 alternatives were examined.An AHP and TOPSIS questionnaire was then designed to prioritize noise control methods in the light of the objectives,criteria,and alternatives.Then,the collected data were fed into Expert Choise.V.11 and Excel and data analysis was carried out using TOPSIS.The results of data analysis indicated that the inconsistency rate in all the cases was smaller than 10%,hence the consistency of the responses was verified.According to the TOPSIS results and experts’opinions about the criteria,implementation and maintenance cost(with a weight of 0.481)and method effectiveness and efficiency(with a weight of 0.046)had the highest and lowest priority respectively.Based on the weights TOPSIS,the appropriate methods for controlling noise in tire manufacturing are designing and manufacturing silencer,requiring people in charge to quickly fix the leaks and change baking press washers on time.展开更多
Water conservancy and hydropower project is an important basic project in our country. Water conservancy and hydropower project is characterized by large investment scale, high technical requirements and high construc...Water conservancy and hydropower project is an important basic project in our country. Water conservancy and hydropower project is characterized by large investment scale, high technical requirements and high construction difficulty. Therefore, there are various risks in the early stage of water conservancy and hydropower project construction, the project implementation stage and the final acceptance and operation stage. These risks will create great difficulties for project managers. It will also make the risk of capital investment more prominent, so we should find out the investment risk and other risks in the process of project management, and explore the risk management. Look for the key factors, so as to deepen the research on water conservancy and hydropower projects. This paper mainly discusses the control methods of risk management of water conservancy and hydropower projects, hope to provide some reference for the current project management of water conservancy and hydropower projects in China and improve the efficiency of project management in China.展开更多
In the whole power supply system, the transmission line is a very key link, and the transmission line determines whether the electricity can be transported smoothly, whether the power grid can operate safely and stabl...In the whole power supply system, the transmission line is a very key link, and the transmission line determines whether the electricity can be transported smoothly, whether the power grid can operate safely and stably. Power system transmission line project has the characteristics of long construction time, many participants, high quality risk and large investment, and has certain particularity compared with ordinary construction projects. This paper uses the investigation method, literature method and analysis method to focus on the transmission line management and quality control method for reference.展开更多
Objective: to analyze the quality control methods of disinfection supply room in CDC. Methods: 100 subjects examined in CDC from February 2020 to February 2021 were selected as the control group, and 100 subjects exam...Objective: to analyze the quality control methods of disinfection supply room in CDC. Methods: 100 subjects examined in CDC from February 2020 to February 2021 were selected as the control group, and 100 subjects examined in CDC from February 2021 to February 2022 as the observation group. The control group was given routine management, while the observation group was given quality control. Results: the management quality of the observation group was better than that of the control group (P<0.05). Conclusion: in the process of disinfection of the disinfection supply room of CDC, effective theoretical control should be adhered to ensure that the examinee receives effective quality management in CDC, and the quality of disinfection and sterilization in CDC should be controlled, so as to avoid cross-infection in the hospital, and at the same time, improve the safety of the examinees inspection, which has a high clinical mechanism. In the process of operation, the effective inspection mechanism should be continuously operated, so as to improve the working ability of the disinfection supply room in an all-round way, which has a high clinical value and ensures disease control.展开更多
Tailless aircraft lack traditional tail structures, which grants them significant stealth capabilities owing to their unique aerodynamic configuration. However, the absence of conventional aerodynamic control surfaces...Tailless aircraft lack traditional tail structures, which grants them significant stealth capabilities owing to their unique aerodynamic configuration. However, the absence of conventional aerodynamic control surfaces and the presence of complex nonlinear dynamics pose considerable challenges for designing their control systems. This paper summarizes the latest advances in innovative effectors and associated control algorithms for tailless aircraft. In addressing the removal of traditional control surfaces, it compares the characteristics of various innovative effectors, highlighting fluid thrust vectoring as an efficient technology well-suited for tailless aircraft. Given the nonlinear characteristics of fluid thrust vectoring, the paper introduces antiwindup control methods and hysteresis suppression strategies, and discusses the challenges and issues related to implementing fluid thrust vectoring. Ultimately, this paper reviews research on maintaining the attitude stability of tailless aircraft through decoupling control, control allocation methods, and reliable control techniques. Despite extensive research on tailless aircraft control, unresolved issues persist. Further in-depth research is necessary to effectively integrate fluid thrust vectoring with tailless aircraft to ensure flight safety.展开更多
Ferromagnetic materials play an important role in memory materials,but conventional control methods are often limited by issues such as high power consumption and volatility.Multiferroic heterostructures provide a pro...Ferromagnetic materials play an important role in memory materials,but conventional control methods are often limited by issues such as high power consumption and volatility.Multiferroic heterostructures provide a promising alternative to achieve low power consumption and nonvolatile electric control of magnetic properties.In this paper,a two-dimensional multiferroic van der Waals heterostructure OsCl_(2)/Sc_(2)CO_(2),which is composed of ferromagnetic monolayer OsCl_(2)and ferroelectric monolayer Sc_(2)CO_(2),is studied by first-principles density functional theory.The results show that by reversing the direction of the electric polarization of Sc_(2)CO_(2),OsCl_(2)can be transformed from a semiconductor to a half-metal,demonstrating a nonvolatile electrical manipulation of the heterostructure through ferroelectric polarization.The underlying physical mechanism is explained by band alignments and charge density differences.Furthermore,based on the heterostructure,we construct a multiferroic tunnel junction with a tunnel electroresistance ratio of 3.38×10^(14)%and a tunnel magnetoresistance ratio of 5.04×10^(6)%,allowing control of conduction states via instantaneous electric or magnetic fields.The findings provide a feasible strategy for designing advanced nanodevices based on the giant tunnel electroresistance and tunnel magnetoresistance effects.展开更多
The topology structure of the artificial neural network is an intelligent control model,which is used for the intelligent vehicle control system and household sweeping robot.When setting the intelligent control system...The topology structure of the artificial neural network is an intelligent control model,which is used for the intelligent vehicle control system and household sweeping robot.When setting the intelligent control system,the connection point of each network is regarded as a neuron in the nervous system,and each connection point has input and output functions.Only when the input of nodes reaches a certain threshold can the output function of nodes be stimulated.Using the networking mode of the artificial neural network model,the mobile node can output in multiple directions.If the input direction of a certain path is the same as that of other nodes,it can choose to avoid and choose another path.The weighted value of each path between nodes is different,which means that the influence of the front node on the current node varies.The control method based on the artificial neural network model can be applied to vehicle control,household sweeping robots,and other fields,and a relatively optimized scheme can be obtained from the aspect of time and energy consumption.展开更多
Prosthetic hands are becoming more and more popular among people without a hand and it is able to perform certain manual operations in function.In biology,action potentials trigger muscle contractions,and surface elec...Prosthetic hands are becoming more and more popular among people without a hand and it is able to perform certain manual operations in function.In biology,action potentials trigger muscle contractions,and surface electromyography（sEMG）signals are the sum of action potentials under the skin exposed by the electrodes（via sebum and solution conduction）.展开更多
Since the reform and opening up,Chinese economy has developed rapidly.Industrial and civil construction projects have made significant progress.That said,it is of great significance to further strengthen the construct...Since the reform and opening up,Chinese economy has developed rapidly.Industrial and civil construction projects have made significant progress.That said,it is of great significance to further strengthen the construction management of industrial and civil construction projects for the longterm development of construction industry in China.In terms of reality,one of the common problems in the current industrial and civil construction is wall cracks,which will have an important impact on the appearance of the building and the overall construction quality.Therefore,it is necessary to analyze the reasons and put forward corresponding measures on it.That is how we can continuously improve the construction quality in civil and industrial construction projects,thereby achieving the enhancement of building safety and stability.展开更多
With ongoing economic,scientific,and technological developments,the electronic devices used in daily lives are developing toward precision and miniaturization,and so the demand for high-precision manufacturing machine...With ongoing economic,scientific,and technological developments,the electronic devices used in daily lives are developing toward precision and miniaturization,and so the demand for high-precision manufacturing machinery is expanding.The most important piece of equipment in modern high-precision manufacturing is the macro-micro motion platform(M3P),which offers high speed,precision,and efficiency and has macro-micro motion coupling characteristics due to its mechanical design and composition of its driving components.Therefore,the design of the control system is crucial for the overall precision of the platform;conventional proportional–integral–derivative control cannot meet the system requirements,and so M3Ps are the subject of a growing range of modern control strategies.This paper begins by describing the development history of M3Ps,followed by their platform structure and motion control system components,and then in-depth assessments of the macro,micro,and macro-micro control systems.In addition to examining the advantages and disadvantages of current macro-micro motion control,recent technological breakthroughs are noted.Finally,based on existing problems,future directions for M3P control systems are given,and the present conclusions offer guidelines for future work on M3Ps.展开更多
The wireless electric vehicle(EV) charging system is highly safe and flexible. To reduce the weight and cost of EVs, the wireless charging system, which simplifies the structure inside an EV and utilizes the transmitt...The wireless electric vehicle(EV) charging system is highly safe and flexible. To reduce the weight and cost of EVs, the wireless charging system, which simplifies the structure inside an EV and utilizes the transmitter-side control method, has become popular. This study investigates the transmitter-side control methods in a wireless EV charging system. First, a universal wireless charging system is introduced, and the function of its transfer power is derived. It is observed that the transfer power can be controlled by regulating either the phase-shift angle or the DC-link voltage. Further, the influence of the control variables is studied using numerical analysis. Additionally, the corresponding control methods, namely the phase-shift angle and the DC-link voltage control, are compared by calculation and simulation. It is found that:(1) the system efficiency is low with the phase-shift control method because of the converter switching loss;(2) the dynamic response is slow with the DC-link voltage control method because of the large inertia of the inductor and capacitor;(3) both the control methods have limitations in their adjustable power range. Therefore, a combined control method is proposed, with the advantages of high system efficiency, fast dynamic response, and wide adjustable power range. Finally, experiments are performed to verify the validity of the theoretical analysis and the effectiveness of the proposed method. This study provides a detailed and comprehensive analysis of the transmitter-side control methods in the wireless charging system, considering the sensitivity of parameters, converter losses, system efficiency,and dynamic performance, with the dead-time effect taken into consideration. Moreover, the proposed control method can be used to realize the optimal combination of the phase-shift angle and the DC-link voltage with good dynamic performance, and it is useful for the optimal operation of the wireless charging system.展开更多
Metals and metalloids（termed as metals in this article）are important constituent elements of the earth＇s crust.A number of metals,if present in excess,are toxic to organisms and therefore they are usually defined a...Metals and metalloids（termed as metals in this article）are important constituent elements of the earth＇s crust.A number of metals,if present in excess,are toxic to organisms and therefore they are usually defined as toxic metals.展开更多
Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the c...Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the characteristics of wave velocity changes tend to become insignificant beyond a certain limit. In contrast, the controllable source electromagnetic method(CSEM) remains highly sensitive to resistivity changes. By simulating different CO_(2) plume migration conditions, we established the relevant models and calculated the corresponding electric field response characteristic curves, allowing us to analyze the CSEM's ability to monitor CO_(2) plumes. We considered potential scenarios for the migration and diffusion of offshore CO_(2) storage, including various burial depths, vertical extension diffusion, lateral extension diffusion,multiple combinations of lateral intervals, and electric field components. We also obtained differences in resistivity inversion imaging obtained by CSEM to evaluate its feasibility in monitoring and to analyze all the electric field(Ex, Ey, and Ez) response characteristics. CSEM has great potential in monitoring CO_(2) plume migration in offshore saltwater reservoirs due to its high sensitivity and accuracy. Furthermore, changes in electromagnetic field response reflect the transport status of CO_(2) plumes, providing an important basis for monitoring and evaluating CO_(2)transport behavior during storage processes.展开更多
Threaded fasteners are one of the most commonly used connection methods for mechanical structures.Its primary function is to generate appropriate clamping forces and fasten the connected parts.An inappropriate preload...Threaded fasteners are one of the most commonly used connection methods for mechanical structures.Its primary function is to generate appropriate clamping forces and fasten the connected parts.An inappropriate preload can cause loosening,fatigue fracture,and other problems.This will affect the safety and reliability of mechanical equipment.The precise control of the preload has become a critical issue in mechanical assembly processes.Over the past few decades,various tightening measures and methods have been proposed to address this issue.However,many problems continue to exist with practical applications that have not been reviewed comprehensively and systematically.First,various control methods were summarized systematically,and their advantages and disadvantages in engineering applications were analyzed.Torque control is the most widely used tightening method owing to its simple operation and low cost.Therefore,the research on the torque control method was summarized systematically from three aspects:the torque-preload correlation formula,effective friction radius,and friction characteristics during tightening.In addition,the special circumstances that may increase preload uncertainty were discussed.Finally,based on a summary of the current research status,the prospects for future research were discussed.This study would aid researchers in extensively understanding the problems in preload control.展开更多
In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when sign...In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when signals are acquired through fiber-optic hydrophones,as these signals often lack physical significance and resist clear systematic modeling.Conventional processing methods,e.g.,low-pass filter(LPF),require a thorough understanding of the effective signal bandwidth for noise reduction,and may introduce undesirable time lags.This paper introduces an innovative feedback control method with dual Kalman filters for the demodulation of phase signals with noises in fiber-optic hydrophones.A mathematical model of the closed-loop system is established to guide the design of the feedback control,aiming to achieve a balance with the input phase signal.The dual Kalman filters are instrumental in mitigating the effects of signal noise,observation noise,and control execution noise,thereby enabling precise estimation for the input phase signals.The effectiveness of this feedback control method is demonstrated through examples,showcasing the restoration of low-noise signals,negative signal-to-noise ratio signals,and multi-frequency signals.This research contributes to the technical advancement of high-performance devices,including fiber-optic hydrophones and phase-locked amplifiers.展开更多
In this paper, two kinds of chaotic systems are controlled respectively with and without time-delay to eliminate their chaotic behaviors. First of all, according to the first-order approximation method and the stabili...In this paper, two kinds of chaotic systems are controlled respectively with and without time-delay to eliminate their chaotic behaviors. First of all, according to the first-order approximation method and the stabilization condition of the linear system, one linear feedback controller is structured to control the chaotic system without time-delay, its chaotic behavior is eliminated and stabilized to its equilibrium. After that, based on the first-order approximation method, the Lyapunov stability theorem, and the matrix inequality theory, the other linear feedback controller is structured to control the chaotic system with time-delay and make it stabilized at its equilibrium. Finally, two numerical examples are given to illustrate the correctness and effectiveness of the two linear feedback controllers.展开更多
So far, most theories of economics and management are under the same premisethat the natural resources are never exhausted and regenerated repeatedly. The magic of technologybrought by industrial revolution endowed hu...So far, most theories of economics and management are under the same premisethat the natural resources are never exhausted and regenerated repeatedly. The magic of technologybrought by industrial revolution endowed human with power that they can do anything they want. Italso turns natural resources into industrial energy and enhances the development of human societyand civilization. Human uses direct comparison of input and output and the satisfaction degree ofdemands to measure the production activities, the economic benefit and management performance,regardless of the change of ecology that serves as the natural resources. However, since theecological environment has been changing worse recently and natural disaster happened frequentlyhuman's dream of conquering the nature has been broken. The nature implements reprisal against humanagain and again, and human is faced with the development limit because of the environmentalrestriction.展开更多
基金co-supported by the National Natural Science Foundation of China(No.52306053)the Science Center for Gas Turbine Project,China(No.P2022-B-Ⅱ-005-001)the National Science and Technology Major Project of China(No.2017-Ⅱ-0010-0024)。
文摘With the continuous increase of aeroengine flight ceiling(>20 km),the thin atmosphere at high altitudes and the size effect all cause the compressor component inlet Reynolds number to decrease rapidly to a critical value(approximately 2.0×10^(5)),and the significant transition process on the blade/endwall surface leads to the sharp degradation of compressor performance,which seriously affects the engine fuel consumption and working stability at high altitudes.In this paper,the research progress on the internal flow mechanism and flow control methods of axial compressors at low Reynolds numbers is reviewed from the aspects of quantification and prediction of performance variation,flow loss mechanism related to separation and transition,efficient transition control and flow field organization.The development trend of the low-Reynolds-number effect of axial flow compressors is noted,and the difficulties and application prospects of aerodynamic design and efficient flow control methods for compressors under low Reynolds numbers at high altitudes are discussed.
文摘First at all, it introduced the concept and the damages of continuous cropping obstacle. Then, it analyzed the causes of continuous cropping obstacles for Atractylodes macrocephala Koidz. In the end, in order to provide guidance for pro- moting sustainable development of Atractylodes macrocephala Koidz industry in Pingjiang County, it put forward some control methods for eliminating continuous cropping obstacles of Atractylodes macrocephala Koidz, including breeding varieties with high resistance; applying rotation cropping and intercropping reasonable; rational fertilization and soil disinfection; introducing antagonistic bacterial and eliminating au- tointoxication.
基金the National Natural Science Foundation of China (50122155)
文摘Based on the dynamics of ABS-equipped vehicles during cornering braking, the electronic brake- force distribution （EBD） control methods of ABS-equipped vehicles during cornering braking are proposed. According to the dynamics and the tire model under tire adhesion limit, the stability acceptance criteria of vehicles during cornering braking are proposed. According to the stability acceptance criteria and the ABS control, the EBD control methods of ABS-equipped vehicles during cornering braking are implemented by adjusting the threshold values of tires slip independently. The vehicle states during cornering braking at two typical initial velocities of the vehicle are analyzed by the EBD control methods, whose results indicate the EBD control methods can improve the braking performances of the vehicle during cornering braking comparing with the ABS control.
基金This study was approved by the Ethics Committee of Kerman University of Medical Sciences.Ethics code(IR.KMU.REC.1397.392).
文摘Undoubtedly,noise has become a major hazardous issue in today’s industrial world,with a lot of people suffering from exposure to excessive noise in their work environments.This study was conducted to weigh and prioritize noise control methods in an Iranian tire manufacturing complex in Iran.The Delphi method and the Technique for Order Preference by Similarity and an Ideal Solution(TOPSIS)were utilized for this purpose.This cross-sectional,descriptive study was conducted in the baking hall of an Iranian tire manufacturing factory in 2016.To weigh and prioritize noise control methods,Analytic Hierarchy Process(AHP)and TOPSIS were applied.In total,4 criteria and 8 alternatives were examined.An AHP and TOPSIS questionnaire was then designed to prioritize noise control methods in the light of the objectives,criteria,and alternatives.Then,the collected data were fed into Expert Choise.V.11 and Excel and data analysis was carried out using TOPSIS.The results of data analysis indicated that the inconsistency rate in all the cases was smaller than 10%,hence the consistency of the responses was verified.According to the TOPSIS results and experts’opinions about the criteria,implementation and maintenance cost(with a weight of 0.481)and method effectiveness and efficiency(with a weight of 0.046)had the highest and lowest priority respectively.Based on the weights TOPSIS,the appropriate methods for controlling noise in tire manufacturing are designing and manufacturing silencer,requiring people in charge to quickly fix the leaks and change baking press washers on time.
文摘Water conservancy and hydropower project is an important basic project in our country. Water conservancy and hydropower project is characterized by large investment scale, high technical requirements and high construction difficulty. Therefore, there are various risks in the early stage of water conservancy and hydropower project construction, the project implementation stage and the final acceptance and operation stage. These risks will create great difficulties for project managers. It will also make the risk of capital investment more prominent, so we should find out the investment risk and other risks in the process of project management, and explore the risk management. Look for the key factors, so as to deepen the research on water conservancy and hydropower projects. This paper mainly discusses the control methods of risk management of water conservancy and hydropower projects, hope to provide some reference for the current project management of water conservancy and hydropower projects in China and improve the efficiency of project management in China.
文摘In the whole power supply system, the transmission line is a very key link, and the transmission line determines whether the electricity can be transported smoothly, whether the power grid can operate safely and stably. Power system transmission line project has the characteristics of long construction time, many participants, high quality risk and large investment, and has certain particularity compared with ordinary construction projects. This paper uses the investigation method, literature method and analysis method to focus on the transmission line management and quality control method for reference.
文摘Objective: to analyze the quality control methods of disinfection supply room in CDC. Methods: 100 subjects examined in CDC from February 2020 to February 2021 were selected as the control group, and 100 subjects examined in CDC from February 2021 to February 2022 as the observation group. The control group was given routine management, while the observation group was given quality control. Results: the management quality of the observation group was better than that of the control group (P<0.05). Conclusion: in the process of disinfection of the disinfection supply room of CDC, effective theoretical control should be adhered to ensure that the examinee receives effective quality management in CDC, and the quality of disinfection and sterilization in CDC should be controlled, so as to avoid cross-infection in the hospital, and at the same time, improve the safety of the examinees inspection, which has a high clinical mechanism. In the process of operation, the effective inspection mechanism should be continuously operated, so as to improve the working ability of the disinfection supply room in an all-round way, which has a high clinical value and ensures disease control.
文摘Tailless aircraft lack traditional tail structures, which grants them significant stealth capabilities owing to their unique aerodynamic configuration. However, the absence of conventional aerodynamic control surfaces and the presence of complex nonlinear dynamics pose considerable challenges for designing their control systems. This paper summarizes the latest advances in innovative effectors and associated control algorithms for tailless aircraft. In addressing the removal of traditional control surfaces, it compares the characteristics of various innovative effectors, highlighting fluid thrust vectoring as an efficient technology well-suited for tailless aircraft. Given the nonlinear characteristics of fluid thrust vectoring, the paper introduces antiwindup control methods and hysteresis suppression strategies, and discusses the challenges and issues related to implementing fluid thrust vectoring. Ultimately, this paper reviews research on maintaining the attitude stability of tailless aircraft through decoupling control, control allocation methods, and reliable control techniques. Despite extensive research on tailless aircraft control, unresolved issues persist. Further in-depth research is necessary to effectively integrate fluid thrust vectoring with tailless aircraft to ensure flight safety.
基金supported by the National Natural Science Foundation of China(Grant Nos.12074213,11574108,and 12104253)the National Key R&D Program of China(Grant No.2022YFA1403103)+2 种基金the Major Basic Program of the Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Provincial(Grant No.ZR2023MA082)the Project of Introduction and Cultivation for Young Innovative Talents in Colleges and Universities of Shandong Province。
文摘Ferromagnetic materials play an important role in memory materials,but conventional control methods are often limited by issues such as high power consumption and volatility.Multiferroic heterostructures provide a promising alternative to achieve low power consumption and nonvolatile electric control of magnetic properties.In this paper,a two-dimensional multiferroic van der Waals heterostructure OsCl_(2)/Sc_(2)CO_(2),which is composed of ferromagnetic monolayer OsCl_(2)and ferroelectric monolayer Sc_(2)CO_(2),is studied by first-principles density functional theory.The results show that by reversing the direction of the electric polarization of Sc_(2)CO_(2),OsCl_(2)can be transformed from a semiconductor to a half-metal,demonstrating a nonvolatile electrical manipulation of the heterostructure through ferroelectric polarization.The underlying physical mechanism is explained by band alignments and charge density differences.Furthermore,based on the heterostructure,we construct a multiferroic tunnel junction with a tunnel electroresistance ratio of 3.38×10^(14)%and a tunnel magnetoresistance ratio of 5.04×10^(6)%,allowing control of conduction states via instantaneous electric or magnetic fields.The findings provide a feasible strategy for designing advanced nanodevices based on the giant tunnel electroresistance and tunnel magnetoresistance effects.
文摘The topology structure of the artificial neural network is an intelligent control model,which is used for the intelligent vehicle control system and household sweeping robot.When setting the intelligent control system,the connection point of each network is regarded as a neuron in the nervous system,and each connection point has input and output functions.Only when the input of nodes reaches a certain threshold can the output function of nodes be stimulated.Using the networking mode of the artificial neural network model,the mobile node can output in multiple directions.If the input direction of a certain path is the same as that of other nodes,it can choose to avoid and choose another path.The weighted value of each path between nodes is different,which means that the influence of the front node on the current node varies.The control method based on the artificial neural network model can be applied to vehicle control,household sweeping robots,and other fields,and a relatively optimized scheme can be obtained from the aspect of time and energy consumption.
基金supported by the National Natural Science Foundation of China(Grant No.51575020)the National Key Technology R&D Program(Grant No.2015BAI02B00)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems
文摘Prosthetic hands are becoming more and more popular among people without a hand and it is able to perform certain manual operations in function.In biology,action potentials trigger muscle contractions,and surface electromyography（sEMG）signals are the sum of action potentials under the skin exposed by the electrodes（via sebum and solution conduction）.
文摘Since the reform and opening up,Chinese economy has developed rapidly.Industrial and civil construction projects have made significant progress.That said,it is of great significance to further strengthen the construction management of industrial and civil construction projects for the longterm development of construction industry in China.In terms of reality,one of the common problems in the current industrial and civil construction is wall cracks,which will have an important impact on the appearance of the building and the overall construction quality.Therefore,it is necessary to analyze the reasons and put forward corresponding measures on it.That is how we can continuously improve the construction quality in civil and industrial construction projects,thereby achieving the enhancement of building safety and stability.
基金This research was supported financially by the China Postdoctoral Science Foundation,the National Natural Science Foundation of China(Grant No.51705132)the Young Backbone Teacher Training Program in Henan University of Technology,the Education Department of Henan Province Natural Science Project(Grant No.21A460006)the Natural Science Project of Henan Provincial Department of Science and Technology(Grant No.222102220088).
文摘With ongoing economic,scientific,and technological developments,the electronic devices used in daily lives are developing toward precision and miniaturization,and so the demand for high-precision manufacturing machinery is expanding.The most important piece of equipment in modern high-precision manufacturing is the macro-micro motion platform(M3P),which offers high speed,precision,and efficiency and has macro-micro motion coupling characteristics due to its mechanical design and composition of its driving components.Therefore,the design of the control system is crucial for the overall precision of the platform;conventional proportional–integral–derivative control cannot meet the system requirements,and so M3Ps are the subject of a growing range of modern control strategies.This paper begins by describing the development history of M3Ps,followed by their platform structure and motion control system components,and then in-depth assessments of the macro,micro,and macro-micro control systems.In addition to examining the advantages and disadvantages of current macro-micro motion control,recent technological breakthroughs are noted.Finally,based on existing problems,future directions for M3P control systems are given,and the present conclusions offer guidelines for future work on M3Ps.
基金supported by the International Science and Technology Cooperation Program of China(Grant No.2016YFE0102200)
文摘The wireless electric vehicle(EV) charging system is highly safe and flexible. To reduce the weight and cost of EVs, the wireless charging system, which simplifies the structure inside an EV and utilizes the transmitter-side control method, has become popular. This study investigates the transmitter-side control methods in a wireless EV charging system. First, a universal wireless charging system is introduced, and the function of its transfer power is derived. It is observed that the transfer power can be controlled by regulating either the phase-shift angle or the DC-link voltage. Further, the influence of the control variables is studied using numerical analysis. Additionally, the corresponding control methods, namely the phase-shift angle and the DC-link voltage control, are compared by calculation and simulation. It is found that:(1) the system efficiency is low with the phase-shift control method because of the converter switching loss;(2) the dynamic response is slow with the DC-link voltage control method because of the large inertia of the inductor and capacitor;(3) both the control methods have limitations in their adjustable power range. Therefore, a combined control method is proposed, with the advantages of high system efficiency, fast dynamic response, and wide adjustable power range. Finally, experiments are performed to verify the validity of the theoretical analysis and the effectiveness of the proposed method. This study provides a detailed and comprehensive analysis of the transmitter-side control methods in the wireless charging system, considering the sensitivity of parameters, converter losses, system efficiency,and dynamic performance, with the dead-time effect taken into consideration. Moreover, the proposed control method can be used to realize the optimal combination of the phase-shift angle and the DC-link voltage with good dynamic performance, and it is useful for the optimal operation of the wireless charging system.
文摘Metals and metalloids（termed as metals in this article）are important constituent elements of the earth＇s crust.A number of metals,if present in excess,are toxic to organisms and therefore they are usually defined as toxic metals.
基金Supported by Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (2019BT02H594)Sanya Technology Innovation Special Project (2022KJCX08)。
文摘Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the characteristics of wave velocity changes tend to become insignificant beyond a certain limit. In contrast, the controllable source electromagnetic method(CSEM) remains highly sensitive to resistivity changes. By simulating different CO_(2) plume migration conditions, we established the relevant models and calculated the corresponding electric field response characteristic curves, allowing us to analyze the CSEM's ability to monitor CO_(2) plumes. We considered potential scenarios for the migration and diffusion of offshore CO_(2) storage, including various burial depths, vertical extension diffusion, lateral extension diffusion,multiple combinations of lateral intervals, and electric field components. We also obtained differences in resistivity inversion imaging obtained by CSEM to evaluate its feasibility in monitoring and to analyze all the electric field(Ex, Ey, and Ez) response characteristics. CSEM has great potential in monitoring CO_(2) plume migration in offshore saltwater reservoirs due to its high sensitivity and accuracy. Furthermore, changes in electromagnetic field response reflect the transport status of CO_(2) plumes, providing an important basis for monitoring and evaluating CO_(2)transport behavior during storage processes.
基金Supported by National Natural Science Foundation of China(Grant Nos.U23B20104,52075012 and 52205510).
文摘Threaded fasteners are one of the most commonly used connection methods for mechanical structures.Its primary function is to generate appropriate clamping forces and fasten the connected parts.An inappropriate preload can cause loosening,fatigue fracture,and other problems.This will affect the safety and reliability of mechanical equipment.The precise control of the preload has become a critical issue in mechanical assembly processes.Over the past few decades,various tightening measures and methods have been proposed to address this issue.However,many problems continue to exist with practical applications that have not been reviewed comprehensively and systematically.First,various control methods were summarized systematically,and their advantages and disadvantages in engineering applications were analyzed.Torque control is the most widely used tightening method owing to its simple operation and low cost.Therefore,the research on the torque control method was summarized systematically from three aspects:the torque-preload correlation formula,effective friction radius,and friction characteristics during tightening.In addition,the special circumstances that may increase preload uncertainty were discussed.Finally,based on a summary of the current research status,the prospects for future research were discussed.This study would aid researchers in extensively understanding the problems in preload control.
基金Project supported by the National Key Research and Development Program of China(No.2022YFB3203600)the National Natural Science Foundation of China(Nos.12172323,12132013+1 种基金12332003)the Zhejiang Provincial Natural Science Foundation of China(No.LZ22A020003)。
文摘In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant challenge.This challenge is further heightened when signals are acquired through fiber-optic hydrophones,as these signals often lack physical significance and resist clear systematic modeling.Conventional processing methods,e.g.,low-pass filter(LPF),require a thorough understanding of the effective signal bandwidth for noise reduction,and may introduce undesirable time lags.This paper introduces an innovative feedback control method with dual Kalman filters for the demodulation of phase signals with noises in fiber-optic hydrophones.A mathematical model of the closed-loop system is established to guide the design of the feedback control,aiming to achieve a balance with the input phase signal.The dual Kalman filters are instrumental in mitigating the effects of signal noise,observation noise,and control execution noise,thereby enabling precise estimation for the input phase signals.The effectiveness of this feedback control method is demonstrated through examples,showcasing the restoration of low-noise signals,negative signal-to-noise ratio signals,and multi-frequency signals.This research contributes to the technical advancement of high-performance devices,including fiber-optic hydrophones and phase-locked amplifiers.
基金Supported by the National Natural Science Foundation of China (61863022)the Natural Science Foundation of Gansu Province(20JR10RA329)Scientific Research and Innovation Fund Project of Gansu University of Chinese Medicine in 2019 (2019KCYB-10)。
文摘In this paper, two kinds of chaotic systems are controlled respectively with and without time-delay to eliminate their chaotic behaviors. First of all, according to the first-order approximation method and the stabilization condition of the linear system, one linear feedback controller is structured to control the chaotic system without time-delay, its chaotic behavior is eliminated and stabilized to its equilibrium. After that, based on the first-order approximation method, the Lyapunov stability theorem, and the matrix inequality theory, the other linear feedback controller is structured to control the chaotic system with time-delay and make it stabilized at its equilibrium. Finally, two numerical examples are given to illustrate the correctness and effectiveness of the two linear feedback controllers.
文摘So far, most theories of economics and management are under the same premisethat the natural resources are never exhausted and regenerated repeatedly. The magic of technologybrought by industrial revolution endowed human with power that they can do anything they want. Italso turns natural resources into industrial energy and enhances the development of human societyand civilization. Human uses direct comparison of input and output and the satisfaction degree ofdemands to measure the production activities, the economic benefit and management performance,regardless of the change of ecology that serves as the natural resources. However, since theecological environment has been changing worse recently and natural disaster happened frequentlyhuman's dream of conquering the nature has been broken. The nature implements reprisal against humanagain and again, and human is faced with the development limit because of the environmentalrestriction.
