With the rapid development of economy and transportation industry, highway construction is often faced with a lot of complex environment, if there is no reasonable economic management measures, then it is easy to redu...With the rapid development of economy and transportation industry, highway construction is often faced with a lot of complex environment, if there is no reasonable economic management measures, then it is easy to reduce the economic benefits of enterprises. Therefore, it is necessary for relevant staff to continuously improve the level of economic efficiency management, timely find the existing deficiencies, reduce the energy consumption of highway construction, achieve the improvement of highway economic efficiency, and enhance the competitiveness of enterprises.展开更多
With China’s rapid economic development,the civil aviation market’s development area has expanded.On this basis,the state has proposed more extensive and stringent civil aviation rules.Many factors can affect the ci...With China’s rapid economic development,the civil aviation market’s development area has expanded.On this basis,the state has proposed more extensive and stringent civil aviation rules.Many factors can affect the civil aircraft during the real operation process,and this can have an impact on the aircraft’s regular functioning to some level.To ensure that civil aircraft remain airworthy,appropriate maintenance work must be performed on a regular basis to prevent compromising the aircraft’s safety performance.For the purpose of reference,this paper discusses the continual airworthiness and maintenance of civil aircraft.展开更多
Based on the construction bridge of Xiamen-Shenzhen high-speed railway(9-32 m simply-supported beam + 6×32 m continuous beam),the pier-beam-track finite element model,where the continuous beam of the ballast trac...Based on the construction bridge of Xiamen-Shenzhen high-speed railway(9-32 m simply-supported beam + 6×32 m continuous beam),the pier-beam-track finite element model,where the continuous beam of the ballast track and simply-supported beam are combined with each other,was established.The laws of the track stress,the pier longitudinal stress and the beam-track relative displacement were analyzed.The results show that reducing the longitudinal resistance can effectively reduce the track stress and the pier stress of the continuous beam,and increase the beam-track relative displacement.Increasing the rigid pier stiffness of continuous beam can reduce the track braking stress,increase the pier longitudinal stress and reduce the beam-track relative displacement,Increasing the rigid pier stiffness of simply-supported beam can reduce the track braking stress,the rigid pier longitudinal stress and the beam-track relative displacement.展开更多
Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne syste...Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne system health monitoring is to find an appropriate health indicator that is highly related to the actual degradation state of the system. This paper proposed a novel health indicator extraction method based on the available sensor parameters for the health monitoring of Air Conditioning System(ACS) of a legacy commercial aircraft model. Firstly, a specific Airplane Condition Monitoring System(ACMS) report for ACS health monitoring is defined. Then a non-parametric modeling technique is adopted to calculate the health indicator based on the raw ACMS report data. The proposed method is validated on a single-aisle commercial aircraft widely used for short and medium-haul routes, using more than 6000 ACMS reports collected from a fleet of aircraft during one year. The case study result shows that the proposed health indicator can effectively characterize the degradation state of the ACS, which can provide valuable information for proactive maintenance plan in advance.展开更多
The samples of fatigue life tests for aeroengine components are usually less than 5,so the evaluation of these samples belongs to small sample analysis. The Weibull distribution is known to describe the life data accu...The samples of fatigue life tests for aeroengine components are usually less than 5,so the evaluation of these samples belongs to small sample analysis. The Weibull distribution is known to describe the life data accurately,and the Weibayes method （developed from Bayesian method） expands on the experiential data in the small sample analysis of fatigue life in aeroengine. Based on the Weibull analysis,a program was developed to improve the efficiency of the reliability analysis for aeroengine compgnents. This program has complete functions and offers highly accurate results. A particular turbine disk＇s low cycle fatigue life was evaluated by this program. From the results,the following conclusions were drawn：（a） that this program could be used for the engineering applications,and （b） while a lack of former test data lowered the validity of evaluation results,the Weibayes method ensured the results of small sample analysis did not deviate from the truth.展开更多
Turbulence is expected to play a relevant role in the so-called conductor gallop phenomena,namely,the high-amplitude,low-frequency oscillation of overhead power lines due to the formation of ice structures and the ens...Turbulence is expected to play a relevant role in the so-called conductor gallop phenomena,namely,the high-amplitude,low-frequency oscillation of overhead power lines due to the formation of ice structures and the ensu-ing effect that wind can have on these.In this work,the galloping time history of a wire with distorted(fixed in time)shape due to the formation of ice is analyzed numerically in the frame of afluid-solid coupling method for different wind speeds and levels of turbulence.The results show that the turbulence intensity has a moderate effect on the increase of the conductor’s aerodynamic lift and drag coefficients due to ice accretion;nevertheless,the corresponding changes in the torsion coefficient are very significant and complicated.A high turbulence intensity can affect the torsion coefficient in a certain range of attack angles and increase the torsion angle of the conductor.Through comparison of the galloping phenomena for different wind velocities,it is found that the related amplitude grows significantly with an increase of the wind speed.For a relatively large wind speed,the galloping amplitude is more sensitive to the turbulence intensity.Moreover,the larger the turbulence intensity,the larger the conductor’s vertical and horizontal galloping amplitudes after icing.The torsion angle also increases with an increase in the wind speed and turbulence intensity.展开更多
The present research focuses on the analysis of wave propagation on a rotating viscoelastic nanobeam supported on the viscoelastic foundation which is subject to thermal gradient effects.A comprehensive and accurate m...The present research focuses on the analysis of wave propagation on a rotating viscoelastic nanobeam supported on the viscoelastic foundation which is subject to thermal gradient effects.A comprehensive and accurate model of a viscoelastic nanobeam is constructed by using a novel nonclassical mechanical model.Based on the general nonlocal theory(GNT),Kelvin-Voigt model,and Timoshenko beam theory,the motion equations for the nanobeam are obtained.Through the GNT,material hardening and softening behaviors are simultaneously taken into account during wave propagation.An analytical solution is utilized to generate the results for torsional(TO),longitudinal(LA),and transverse(TA)types of wave dispersion.Moreover,the effects of nonlocal parameters,Kelvin-Voigt damping,foundation damping,Winkler-Pasternak coefficients,rotating speed,and thermal gradient are illustrated and discussed in detail.展开更多
An active and reactive combined spot price model and the corresponding algorithm are introduced in this paper based on the theory of optimal power flow. Different from the traditional economic dispatch in the field of...An active and reactive combined spot price model and the corresponding algorithm are introduced in this paper based on the theory of optimal power flow. Different from the traditional economic dispatch in the field of spot price, the objective function is to minimize generation costs based on pricing reactive power. Then considering the characteristics of wind turbines, processing methods of wind farms in optimal power flow is discussed. Finally, the feasibility of the model and the algorithm is verified through the simulation results of IEEE 30 system.展开更多
The paper presents process of creating a centrifugal pump rotor model in CAD environment. Modeling of a virtual object was divided into two stages, modeling of the efficient pump and the simulated failure of one of th...The paper presents process of creating a centrifugal pump rotor model in CAD environment. Modeling of a virtual object was divided into two stages, modeling of the efficient pump and the simulated failure of one of the impeller＇s blades. Comparison of the results of the resonance frequency obtained from the model analysis, with those obtained from measurements on the actual object was shown. Measurements and simulations were conducted on the pump before and after the simulated damaged of the rotor. In order to verify the model the rotor of pump was weighted and compared with the masses of the respective components obtained from the virtual object. In the second stage genuine rotor was subjected to the experimental modal analysis.展开更多
Modularized circuit designs for chaotic systems are introduced in this paper.Especially,a typical improved modularized design strategy is proposed and applied to a new hyper-chaotic system circuit implementation.In th...Modularized circuit designs for chaotic systems are introduced in this paper.Especially,a typical improved modularized design strategy is proposed and applied to a new hyper-chaotic system circuit implementation.In this paper,the detailed design procedures are described.Multisim simulations and physical experiments are conducted,and the simulation results are compared with Matlab simulation results for different system parameter pairs.These results are consistent with each other and they verify the existence of the hyper-chaotic attractor for this new hyper-chaotic system.展开更多
This paper discusses an implementation based on CMEX S-functions to model and to check implementation feasibility of two most commonly used Maximum Power Point Tracking （MPPT） algorithms, namely Hill Climbing/Pertu...This paper discusses an implementation based on CMEX S-functions to model and to check implementation feasibility of two most commonly used Maximum Power Point Tracking （MPPT） algorithms, namely Hill Climbing/Perturb ＆ Observe （P＆O） and Incremental Conductance. This study can also be generalized to encompass the whole digital techniques family, including artificial intelligence like Neural Network and Fuzzy Logic Control.展开更多
Concepts of precision engineering design process for optimal design where engineering sciences contribute in the successful good design are elaborated in this paper.Scientific theory and practicality are discussed in ...Concepts of precision engineering design process for optimal design where engineering sciences contribute in the successful good design are elaborated in this paper.Scientific theory and practicality are discussed in this paper.Factors necessary for a complete product or systems design are detailed and application of mathematical design optimization in producing a good design are shown.Many applicable engineering design examples are itemized to show relevancy of the optimal design theory to engineering design.Future trends of optimal design with respect to the 4th industrial revolution of digitization are presented.Paper sets to elaborate that most of the engineering and scientific design problems can be optimized to a good design based on many new/advanced optimization techniques.展开更多
The coke plant of a steel plant corresponds to the area that transforms a blend of coal into coke for using in blast furnace and steam to power plant. The coking plant of ThyssenKrupp CSA uses the heat recovery techno...The coke plant of a steel plant corresponds to the area that transforms a blend of coal into coke for using in blast furnace and steam to power plant. The coking plant of ThyssenKrupp CSA uses the heat recovery technology with stamping charger for stamping and preparation a blend of coals for charging and coking. Stamping technology adds several benefits to the process, such as increased density, homogeneity and alignment of the coal cake charged into the oven, as well as provides better control of the coking process, improves parameters of coke quality and allows coal blending with lower coking power, thereby reducing the production cost of coke and power generation. Through the automation of stamping charger, it is possible to evaluate and calculate the stamped coal density charged and the productivity gains this system provides.展开更多
This research presents a novel approach to pipeline Structure Health Monitoring(SHM)by utilizing frequency response function signals and integrating advanced data-driven techniques to detect and evaluate vibration res...This research presents a novel approach to pipeline Structure Health Monitoring(SHM)by utilizing frequency response function signals and integrating advanced data-driven techniques to detect and evaluate vibration responses regarding loose bolts,scale deposits within pipelines,and cracks at pipeline supports,aiming to determine the effectiveness of utilizing artificial neural networks(ANN)and an ensemble learning approach in detecting the aforementioned damages through a data-driven approach.The research starts by recording 6500 samples captured by two accelerometers,related to 11 replicated pipeline structural scenarios.The research demonstrated the potential of principal component analysis(PCA)in dimensionality reduction,achieving approximately 81%reduction in data set 1 acquired by accelerometer 1 and around 79.5%in data set 2 acquired by accelerometer 2,without significant loss of information.Additionally,two ANN base models were employed for fault recognition and classification,achieving over 99.88%accuracy and mean squared error values ranging from 0.00006 to 0.00019.A significant innovation of this work lies in the implementation of an ensemble learning approach,which integrates the strengths of the base models,showcasing outstanding performance that was proved consistent across multiple iterations,effectively mitigating the weaknesses of the base models and providing a reliable fault classification and prediction system.This research underscores the effectiveness of combining PCA,ANN,k-fold cross-validation,and ensemble learning techniques in pipeline SHM for improved reliability and safety.The findings highlight the potential for broader applications of this methodology in real-world scenarios,addressing urgent challenges faced by infrastructure owners and operators.展开更多
This paper puts forward a new fault diagnosis model based on Petri net.In this new fault diagnosis method,an associated tree is f irst defi ned to describe the logic according to the protections and circuit breakers.A...This paper puts forward a new fault diagnosis model based on Petri net.In this new fault diagnosis method,an associated tree is f irst defi ned to describe the logic according to the protections and circuit breakers.After that a Petri net diagnosis model comes into being and the precise diagnosis of power grid elements can be realized at the same time.The simulation results given in this paper illustrate that this fault diagnosis method can make a rapid diagnosis in complex fault situation and give accurate results to power grid fault diagnosis.展开更多
Having cholesterol in our body is essential for living healthy,but too much can lead to serious health problems,including-but not limited to-heart attacks and strokes(1).Indeed,accumulating evidence points to choleste...Having cholesterol in our body is essential for living healthy,but too much can lead to serious health problems,including-but not limited to-heart attacks and strokes(1).Indeed,accumulating evidence points to cholesterol as a cancer risk factor especially in colon,rectal,prostatic and testicular cancer(2).Cholesterol is the most abundant sterol in animal tissues with many important functions that spans from simply maintaining cell membrane physical properties to the production of bile acids and biosynthesis of steroid hormones.For the most part,cholesterol is synthetised de novo in the liver,but some is obtained from dietary intake.The synthesis of cholesterol takes place in the cytoplasm and the endoplasmic reticulum(ER)of hepatocytes(the major liver cell types)and starts with one molecule of acetyl-CoA.展开更多
文摘With the rapid development of economy and transportation industry, highway construction is often faced with a lot of complex environment, if there is no reasonable economic management measures, then it is easy to reduce the economic benefits of enterprises. Therefore, it is necessary for relevant staff to continuously improve the level of economic efficiency management, timely find the existing deficiencies, reduce the energy consumption of highway construction, achieve the improvement of highway economic efficiency, and enhance the competitiveness of enterprises.
文摘With China’s rapid economic development,the civil aviation market’s development area has expanded.On this basis,the state has proposed more extensive and stringent civil aviation rules.Many factors can affect the civil aircraft during the real operation process,and this can have an impact on the aircraft’s regular functioning to some level.To ensure that civil aircraft remain airworthy,appropriate maintenance work must be performed on a regular basis to prevent compromising the aircraft’s safety performance.For the purpose of reference,this paper discusses the continual airworthiness and maintenance of civil aircraft.
基金Project(50678176) supported by the National Natural Science Foundation of China
文摘Based on the construction bridge of Xiamen-Shenzhen high-speed railway(9-32 m simply-supported beam + 6×32 m continuous beam),the pier-beam-track finite element model,where the continuous beam of the ballast track and simply-supported beam are combined with each other,was established.The laws of the track stress,the pier longitudinal stress and the beam-track relative displacement were analyzed.The results show that reducing the longitudinal resistance can effectively reduce the track stress and the pier stress of the continuous beam,and increase the beam-track relative displacement.Increasing the rigid pier stiffness of continuous beam can reduce the track braking stress,increase the pier longitudinal stress and reduce the beam-track relative displacement,Increasing the rigid pier stiffness of simply-supported beam can reduce the track braking stress,the rigid pier longitudinal stress and the beam-track relative displacement.
基金supported by the National Natural Science Foundation of China (61403198)the Jiangsu Province Natural Science Foundation of China (BK20140827)China Postdoctoral Science Foundation (2015M581792)
文摘Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne system health monitoring is to find an appropriate health indicator that is highly related to the actual degradation state of the system. This paper proposed a novel health indicator extraction method based on the available sensor parameters for the health monitoring of Air Conditioning System(ACS) of a legacy commercial aircraft model. Firstly, a specific Airplane Condition Monitoring System(ACMS) report for ACS health monitoring is defined. Then a non-parametric modeling technique is adopted to calculate the health indicator based on the raw ACMS report data. The proposed method is validated on a single-aisle commercial aircraft widely used for short and medium-haul routes, using more than 6000 ACMS reports collected from a fleet of aircraft during one year. The case study result shows that the proposed health indicator can effectively characterize the degradation state of the ACS, which can provide valuable information for proactive maintenance plan in advance.
文摘The samples of fatigue life tests for aeroengine components are usually less than 5,so the evaluation of these samples belongs to small sample analysis. The Weibull distribution is known to describe the life data accurately,and the Weibayes method （developed from Bayesian method） expands on the experiential data in the small sample analysis of fatigue life in aeroengine. Based on the Weibull analysis,a program was developed to improve the efficiency of the reliability analysis for aeroengine compgnents. This program has complete functions and offers highly accurate results. A particular turbine disk＇s low cycle fatigue life was evaluated by this program. From the results,the following conclusions were drawn：（a） that this program could be used for the engineering applications,and （b） while a lack of former test data lowered the validity of evaluation results,the Weibayes method ensured the results of small sample analysis did not deviate from the truth.
基金This work was supported in part by the National Natural Science Foundation of China[Grant No.51867013].
文摘Turbulence is expected to play a relevant role in the so-called conductor gallop phenomena,namely,the high-amplitude,low-frequency oscillation of overhead power lines due to the formation of ice structures and the ensu-ing effect that wind can have on these.In this work,the galloping time history of a wire with distorted(fixed in time)shape due to the formation of ice is analyzed numerically in the frame of afluid-solid coupling method for different wind speeds and levels of turbulence.The results show that the turbulence intensity has a moderate effect on the increase of the conductor’s aerodynamic lift and drag coefficients due to ice accretion;nevertheless,the corresponding changes in the torsion coefficient are very significant and complicated.A high turbulence intensity can affect the torsion coefficient in a certain range of attack angles and increase the torsion angle of the conductor.Through comparison of the galloping phenomena for different wind velocities,it is found that the related amplitude grows significantly with an increase of the wind speed.For a relatively large wind speed,the galloping amplitude is more sensitive to the turbulence intensity.Moreover,the larger the turbulence intensity,the larger the conductor’s vertical and horizontal galloping amplitudes after icing.The torsion angle also increases with an increase in the wind speed and turbulence intensity.
文摘The present research focuses on the analysis of wave propagation on a rotating viscoelastic nanobeam supported on the viscoelastic foundation which is subject to thermal gradient effects.A comprehensive and accurate model of a viscoelastic nanobeam is constructed by using a novel nonclassical mechanical model.Based on the general nonlocal theory(GNT),Kelvin-Voigt model,and Timoshenko beam theory,the motion equations for the nanobeam are obtained.Through the GNT,material hardening and softening behaviors are simultaneously taken into account during wave propagation.An analytical solution is utilized to generate the results for torsional(TO),longitudinal(LA),and transverse(TA)types of wave dispersion.Moreover,the effects of nonlocal parameters,Kelvin-Voigt damping,foundation damping,Winkler-Pasternak coefficients,rotating speed,and thermal gradient are illustrated and discussed in detail.
文摘An active and reactive combined spot price model and the corresponding algorithm are introduced in this paper based on the theory of optimal power flow. Different from the traditional economic dispatch in the field of spot price, the objective function is to minimize generation costs based on pricing reactive power. Then considering the characteristics of wind turbines, processing methods of wind farms in optimal power flow is discussed. Finally, the feasibility of the model and the algorithm is verified through the simulation results of IEEE 30 system.
文摘The paper presents process of creating a centrifugal pump rotor model in CAD environment. Modeling of a virtual object was divided into two stages, modeling of the efficient pump and the simulated failure of one of the impeller＇s blades. Comparison of the results of the resonance frequency obtained from the model analysis, with those obtained from measurements on the actual object was shown. Measurements and simulations were conducted on the pump before and after the simulated damaged of the rotor. In order to verify the model the rotor of pump was weighted and compared with the masses of the respective components obtained from the virtual object. In the second stage genuine rotor was subjected to the experimental modal analysis.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.61403395)the Natural Science Foundation of Tianjin,China(Grant No.13JCYBJC39000)+3 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of Chinathe Fund from the Tianjin Key Laboratory of Civil Aircraft Airworthiness and Maintenance in Civil Aviation of China(Grant No.104003020106)the National Basic Research Program of China(Grant No.2014CB744904)the Fund for the Scholars of Civil Aviation University of China(Grant No.2012QD21x)
文摘Modularized circuit designs for chaotic systems are introduced in this paper.Especially,a typical improved modularized design strategy is proposed and applied to a new hyper-chaotic system circuit implementation.In this paper,the detailed design procedures are described.Multisim simulations and physical experiments are conducted,and the simulation results are compared with Matlab simulation results for different system parameter pairs.These results are consistent with each other and they verify the existence of the hyper-chaotic attractor for this new hyper-chaotic system.
文摘This paper discusses an implementation based on CMEX S-functions to model and to check implementation feasibility of two most commonly used Maximum Power Point Tracking （MPPT） algorithms, namely Hill Climbing/Perturb ＆ Observe （P＆O） and Incremental Conductance. This study can also be generalized to encompass the whole digital techniques family, including artificial intelligence like Neural Network and Fuzzy Logic Control.
文摘Concepts of precision engineering design process for optimal design where engineering sciences contribute in the successful good design are elaborated in this paper.Scientific theory and practicality are discussed in this paper.Factors necessary for a complete product or systems design are detailed and application of mathematical design optimization in producing a good design are shown.Many applicable engineering design examples are itemized to show relevancy of the optimal design theory to engineering design.Future trends of optimal design with respect to the 4th industrial revolution of digitization are presented.Paper sets to elaborate that most of the engineering and scientific design problems can be optimized to a good design based on many new/advanced optimization techniques.
文摘The coke plant of a steel plant corresponds to the area that transforms a blend of coal into coke for using in blast furnace and steam to power plant. The coking plant of ThyssenKrupp CSA uses the heat recovery technology with stamping charger for stamping and preparation a blend of coals for charging and coking. Stamping technology adds several benefits to the process, such as increased density, homogeneity and alignment of the coal cake charged into the oven, as well as provides better control of the coking process, improves parameters of coke quality and allows coal blending with lower coking power, thereby reducing the production cost of coke and power generation. Through the automation of stamping charger, it is possible to evaluate and calculate the stamped coal density charged and the productivity gains this system provides.
文摘This research presents a novel approach to pipeline Structure Health Monitoring(SHM)by utilizing frequency response function signals and integrating advanced data-driven techniques to detect and evaluate vibration responses regarding loose bolts,scale deposits within pipelines,and cracks at pipeline supports,aiming to determine the effectiveness of utilizing artificial neural networks(ANN)and an ensemble learning approach in detecting the aforementioned damages through a data-driven approach.The research starts by recording 6500 samples captured by two accelerometers,related to 11 replicated pipeline structural scenarios.The research demonstrated the potential of principal component analysis(PCA)in dimensionality reduction,achieving approximately 81%reduction in data set 1 acquired by accelerometer 1 and around 79.5%in data set 2 acquired by accelerometer 2,without significant loss of information.Additionally,two ANN base models were employed for fault recognition and classification,achieving over 99.88%accuracy and mean squared error values ranging from 0.00006 to 0.00019.A significant innovation of this work lies in the implementation of an ensemble learning approach,which integrates the strengths of the base models,showcasing outstanding performance that was proved consistent across multiple iterations,effectively mitigating the weaknesses of the base models and providing a reliable fault classification and prediction system.This research underscores the effectiveness of combining PCA,ANN,k-fold cross-validation,and ensemble learning techniques in pipeline SHM for improved reliability and safety.The findings highlight the potential for broader applications of this methodology in real-world scenarios,addressing urgent challenges faced by infrastructure owners and operators.
文摘This paper puts forward a new fault diagnosis model based on Petri net.In this new fault diagnosis method,an associated tree is f irst defi ned to describe the logic according to the protections and circuit breakers.After that a Petri net diagnosis model comes into being and the precise diagnosis of power grid elements can be realized at the same time.The simulation results given in this paper illustrate that this fault diagnosis method can make a rapid diagnosis in complex fault situation and give accurate results to power grid fault diagnosis.
基金SP and CB acknowledge the research funding from Rosetrees Trust(M894)and Guts UK(DGO2019_02).
文摘Having cholesterol in our body is essential for living healthy,but too much can lead to serious health problems,including-but not limited to-heart attacks and strokes(1).Indeed,accumulating evidence points to cholesterol as a cancer risk factor especially in colon,rectal,prostatic and testicular cancer(2).Cholesterol is the most abundant sterol in animal tissues with many important functions that spans from simply maintaining cell membrane physical properties to the production of bile acids and biosynthesis of steroid hormones.For the most part,cholesterol is synthetised de novo in the liver,but some is obtained from dietary intake.The synthesis of cholesterol takes place in the cytoplasm and the endoplasmic reticulum(ER)of hepatocytes(the major liver cell types)and starts with one molecule of acetyl-CoA.
