The tube rotation method （TRM） refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The influence of the TRM on transverse w...The tube rotation method （TRM） refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The influence of the TRM on transverse wall thickness precision of seamless steel tube was studied. Thickness distribution of the TRM was obtained by superimposing the thickened amount of single pass rolling. Results show that the TRM can effectively improve the evenness of thickness distribution. In order to analyze the influence mechanism of the TRM, the finite element method was adopted to simulate the thickness distribution in stretch reduction process. Results show that the TRM changes the roundtrip flow between two fix places of conventional stretch reducing and inhibits the directional accumulation of metal. In addition, the TRM has a correction effect on thickness cusp. All these advantages of the TRM help to improve the transverse wall thickness precision of seamless steel tube.展开更多
In atomic,molecular,and nuclear physics,the method of complex coordinate rotation is a widely used theoretical tool for studying resonant states.Here,we propose a novel implementation of this method based on the gradi...In atomic,molecular,and nuclear physics,the method of complex coordinate rotation is a widely used theoretical tool for studying resonant states.Here,we propose a novel implementation of this method based on the gradient optimization(CCR-GO).The main strength of the CCR-GO method is that it does not require manual adjustment of optimization parameters in the wave function;instead,a mathematically well-defined optimization path can be followed.Our method is proven to be very efficient in searching resonant positions and widths over a variety of few-body atomic systems,and can significantly improve the accuracy of the results.As a special case,the CCR-GO method is equally capable of dealing with bound-state problems with high accuracy,which is traditionally achieved through the usual extreme conditions of energy itself.展开更多
For the test of rotation speed of high spinning projectile, the general formula of the motional electromotive force （MEMF） of planar magnetic induction coil （PMIC） is derived in case of 3D rotation in a stable mag...For the test of rotation speed of high spinning projectile, the general formula of the motional electromotive force （MEMF） of planar magnetic induction coil （PMIC） is derived in case of 3D rotation in a stable magnetic field. Under a reasona-ble assumption, the MEMF of PMIC is simplified after the aforementioned general formula is used to calculate high spinning PMIC in the geomagnetic field environment. The determination approach of half-cycle is discussed and the method of rotation speed test is studied, and a test is conducted in the paper. The rotation speed curve obtained by the approach in this paper is consistent with the curve by telemetry.展开更多
The increase of quality consciousness brings about the growth of significance of metrological systems. Besides the significance, the level of automatization, flexibility, accuracy, et al. have advanced. The modern mea...The increase of quality consciousness brings about the growth of significance of metrological systems. Besides the significance, the level of automatization, flexibility, accuracy, et al. have advanced. The modern measuring systems are constructed so that nearly all necessary dimensional characteristics can be measured with them. However, conventional measuring systems are provided for particular mode measurements. This research paper presents and compares several conventional and modem measuring systems and methods. The measured value is roundness, one of the basic shapes of cross section in mechanical engineering. This paper arises in search of answers for the question whether conventional measuring techniques and equipments are made redundant because of the modern ones. In what segments and in which criterion are modem methods preferable？展开更多
Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transfor...Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle,so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle.By extracting the direct current(DC)component and the alternating current(AC)component of the light intensity signal detected by the photoelectric detector(PD),the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components,and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform.The experimental results show that the relative error of current measurement does not exceed 1.40%in the current range of 0.05—0.50 A,which is less than the approximate linear measurement(ALM)method,and the magnetic rotation angle and the current have a good linear relationship.展开更多
We study the dimensionless spin parameter j ≡ cJ/（GM2） of different kinds of uniformly rotating compact stars, including traditional neutron stars, hyperonic neutron stars and hybrid stars, based on relativistic me...We study the dimensionless spin parameter j ≡ cJ/（GM2） of different kinds of uniformly rotating compact stars, including traditional neutron stars, hyperonic neutron stars and hybrid stars, based on relativistic mean field theory and the MIT bag model. It is found that j ~ 0.7, which had been suggested in traditional neutron stars, is sustained for hyperonic neutron stars and hybrid stars with M 〉 0.5 MG. Not the interior but rather the crust structure of the stars is a key factor to determine jmax for three kinds of selected compact stars. Furthermore, a universal formula j = 0.63（f/fK） -- 0.42（f/fK）2 ＋ 0.48（f/fK）z is suggested to determine the spin parameter at any rotational frequency f smaller than the Keplerian frequency fK.展开更多
Real-time simulation of industrial equipment is a huge challenge nowadays. The high performance and fine-grained parallel computing provided by graphics processing units （GPUs） bring us closer to our goals. In this ...Real-time simulation of industrial equipment is a huge challenge nowadays. The high performance and fine-grained parallel computing provided by graphics processing units （GPUs） bring us closer to our goals. In this article, an industrial-scale rotating drum is simulated using simplified discrete element method （DEM） without consideration of the tangential components of contact force and particle rotation. A single GPU is used first to simulate a small model system with about 8000 particles in real-time, and the simulation is then scaled up to industrial scale using more than 200 GPUs in a 1 D domain-decomposition parallelization mode. The overall speed is about 1/11 of the real-time. Optimization of the communication part of the parallel GPU codes can speed up the simulation further, indicating that such real-time simulations have not only methodological but also industrial implications in the near future.展开更多
This paper presents a low?complexity method for the direction?of?arrival(DOA)estimation of noncircular signals for coprime sensor arrays.The noncircular property is exploited to improve the performance of DOA estimati...This paper presents a low?complexity method for the direction?of?arrival(DOA)estimation of noncircular signals for coprime sensor arrays.The noncircular property is exploited to improve the performance of DOA estimation.To reduce the computational complexity,the rotational invariance propagator method(RIPM)is included in the algorithm.First,the extended array output is reconstructed by combining the array output and its conjugated counterpart.Then,the RIPM is utilized to obtain two sets of DOA estimates for two subarrays.Finally,the true DOAs are estimated by combining the consistent results of the two subarrays.This illustrates the potential gain that both noncircularity and coprime arrays provide when considered together.The proposed algorithm has a lower computational complexity and a better DOA estimation performance than the standard estimation of signal parameters by the rotational invariance technique and Capon algorithm.Numerical simulation results illustrate the effectiveness and superiority of the proposed algorithm.展开更多
Segregation and mixing of granular materials are complex processes and are not fully understood. Motivated by industrial need, we performed a simulation using the discrete element method to study size segregation of a...Segregation and mixing of granular materials are complex processes and are not fully understood. Motivated by industrial need, we performed a simulation using the discrete element method to study size segregation of a binary mixture of granular particles in a horizontal rotating drum. Particles of two dif- ferent sizes were poured into the drum until it was 50% full. Shear-driven segregation was induced by rotating the side-plates of the drum in the opposite direction to that of the cylindrical wall. We found that radial segregation diminished in these systems but did not completely vanish. In an ordinary rotating drum, a radial core of smaller particles is formed in the center of the drum, surrounded by larger revolving particles. In our system, however, the smaller particles were found to migrate toward the side-plates. The shear from anti-spinning side-plates reduces the voidage and increases the bulk density. As such, smaller particles in the mixer tend to move to denser regions. We varied the shear by changing the coefficient of friction on the side-plates to study the influence of shear rate on this migration. We also compared the extent of radial segregation with stationary side-plates and with side-plates moving in different angular directions.展开更多
Ideal proportional navigation （IPN） is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation. The closed-form solution of two- dimensional ideal proportional n...Ideal proportional navigation （IPN） is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation. The closed-form solution of two- dimensional ideal proportional navigation was conducted in previous public literature, whereas the practical interception happens in the three-dimensional space. A novel set of relative dynamic equations is adopted in this paper, which is with the advantage of decoupling relative motion in the instantaneous rotation plane of the line of sight from the rotation of this plane. The dimension-reduced IPN is constructed in this instantaneous plane, which functions as a three-dimensional guidance law. The trajectory features of dimension-reduced IPN are explored, and the capture regions of dimension-reduced IPN with limited acceleration against nonmaneuvering and maneuvering targets are analyzed by using phase plane method. It is proved that the capture capability of IPN is much stronger than true proportional navigation （TPN）, no matter the target maneuvers or not. Finally, simulation results indicate that IPN is more effective than TPN in exoatmospheric interception scenarios.展开更多
In this paper,the parameterized Marcinkiewicz integrals with variable kernels defined by μΩ^ρ（f）（x）=（∫0^∞│∫│1-y│≤t Ω（x,x-y）/│x-y│^n-p f（y）dy│^2dt/t1＋2p）^1/2 are investigated.It is proved that ...In this paper,the parameterized Marcinkiewicz integrals with variable kernels defined by μΩ^ρ（f）（x）=（∫0^∞│∫│1-y│≤t Ω（x,x-y）/│x-y│^n-p f（y）dy│^2dt/t1＋2p）^1/2 are investigated.It is proved that if Ω∈ L∞（R^n） × L^r（S^n-1）（r〉（n-n1p＇/n） is an odd function in the second variable y,then the operator μΩ^ρ is bounded from L^p（R^n） to L^p（R^n） for 1 〈 p ≤ max{（n＋1）/2,2}.It is also proved that,if Ω satisfies the L^1-Dini condition,then μΩ^ρ is of type（p,p） for 1 〈 p ≤ 2,of the weak type（1,1） and bounded from H1 to L1.展开更多
Hot isostatic pressing(HIP)is a critical powder metallurgy technique for manufacturing high-performance components.However,achieving uniform powder distribution within complex capsules is challenging,particularly in c...Hot isostatic pressing(HIP)is a critical powder metallurgy technique for manufacturing high-performance components.However,achieving uniform powder distribution within complex capsules is challenging,particularly in critical low-density regions where inadequate powder filling leads to non-uniform deformation and potential part rejection after HIP.This study investigated the powder filling and packing densification behavior of Ti-6Al-4V particles through discrete element method(DEM)simulations to develop an enhanced densification technique targeting these critical regions.A new rotational centrifugal method was proposed to address this challenge.Results demonstrated that vertical vibration achieved limited improvement,and horizontal vibration exhibited non-uniform powder distribution.The proposed rotational centrifugal method at 200 rpm proved most effective,achieving the highest relative density with superior uniformity and rapid densification.The analysis in rotational motion revealed that rapid densification originates from consistent centrifugal forces.Upon stopping rotation,particles undergo localized vigorous motion,resulting in a slight decrease in relative density.To address this,an optimized deceleration scheme was developed.It achieved a relative density of 0.549,representing improvements of 70.5%over vertical vibration and 4.2%over horizontal vibration.These findings provide valuable insights for optimizing pre-HIP processing parameters for complex components,offering a promising solution for addressing powder filling challenges.展开更多
Aiming at resolving the limitation of the speed regulation range of sensorless control technology,a new composite sensorless control strategy is proposed to realize a control method for a permanent magnet synchronous ...Aiming at resolving the limitation of the speed regulation range of sensorless control technology,a new composite sensorless control strategy is proposed to realize a control method for a permanent magnet synchronous motor(PMSM)in full speed range.In the medium-and high-speed range,the improved new sliding mode observer method is used to estimate the motor speed and rotor position information.In the zero and low speed range,in order to avoid the defects of the sliding mode method,the rotating high-frequency voltage signal injection method is used.When switching between low,medium,and high speed,the fuzzy control algorithm is adopted to achieve smooth transitions.The simulation experiment results show that the hybrid mode combining the sliding mode observer and rotating high-frequency voltage injection methods,can effectively reduce the jitter in the algorithm switching process,and realize the smooth control of a PMSM in full speed range.展开更多
Aim:This paper addresses the assessment of the composition of a general wound,in terms of all identifiable categories of tissue and pigmentation in an attempt to improve accuracy in assessing and monitoring wound heal...Aim:This paper addresses the assessment of the composition of a general wound,in terms of all identifiable categories of tissue and pigmentation in an attempt to improve accuracy in assessing and monitoring wound health.Materials and Methods:A knowledgebase of clusters was built into the hue,saturation and intensity(HSI)color space and then used for assessing wound composition.Based on the observation that the clusters are fairly distinct,two different algorithms,that is,Mahalanobis distance(MD)based and the rotated coordinate system(RCS)method,were used for classification.These methods exploit the shape,spread,and orientation of each cluster.Results:The clusters in the HSI color space,built from about 9,000(calibrated)pixels from 48 images of various wound beds,showed 8 fairly distinct regions.The inter-cluster distances were consistent with the visual appearance.The efficacy of the MD and RCS based methods in 120 experiments taken from a set of 15 test images(in terms of average percent-match)was found to be 91.55 and 93.71,respectively.Conclusion:Our investigations established eight categories of tissue and pigmentation in wound beds.These findings help to determine the stage of wound healing more accurately and comprehensively than typically permitted through use of the 4-color model reported in the literature for addressing specific wound types.展开更多
文摘The tube rotation method （TRM） refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The influence of the TRM on transverse wall thickness precision of seamless steel tube was studied. Thickness distribution of the TRM was obtained by superimposing the thickened amount of single pass rolling. Results show that the TRM can effectively improve the evenness of thickness distribution. In order to analyze the influence mechanism of the TRM, the finite element method was adopted to simulate the thickness distribution in stretch reduction process. Results show that the TRM changes the roundtrip flow between two fix places of conventional stretch reducing and inhibits the directional accumulation of metal. In addition, the TRM has a correction effect on thickness cusp. All these advantages of the TRM help to improve the transverse wall thickness precision of seamless steel tube.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91636216,11974382,and 11474316)the Chinese Academy of Sciences Strategic Priority Research Program(Grant No.XDB21020200)+1 种基金by the YIPA Programthe support of NSERC,SHARCnet,ACEnet of Canada。
文摘In atomic,molecular,and nuclear physics,the method of complex coordinate rotation is a widely used theoretical tool for studying resonant states.Here,we propose a novel implementation of this method based on the gradient optimization(CCR-GO).The main strength of the CCR-GO method is that it does not require manual adjustment of optimization parameters in the wave function;instead,a mathematically well-defined optimization path can be followed.Our method is proven to be very efficient in searching resonant positions and widths over a variety of few-body atomic systems,and can significantly improve the accuracy of the results.As a special case,the CCR-GO method is equally capable of dealing with bound-state problems with high accuracy,which is traditionally achieved through the usual extreme conditions of energy itself.
基金National Key Lab for Electronic Measurement and Technology,North University of China(No.9140C120401080C12)
文摘For the test of rotation speed of high spinning projectile, the general formula of the motional electromotive force （MEMF） of planar magnetic induction coil （PMIC） is derived in case of 3D rotation in a stable magnetic field. Under a reasona-ble assumption, the MEMF of PMIC is simplified after the aforementioned general formula is used to calculate high spinning PMIC in the geomagnetic field environment. The determination approach of half-cycle is discussed and the method of rotation speed test is studied, and a test is conducted in the paper. The rotation speed curve obtained by the approach in this paper is consistent with the curve by telemetry.
文摘The increase of quality consciousness brings about the growth of significance of metrological systems. Besides the significance, the level of automatization, flexibility, accuracy, et al. have advanced. The modern measuring systems are constructed so that nearly all necessary dimensional characteristics can be measured with them. However, conventional measuring systems are provided for particular mode measurements. This research paper presents and compares several conventional and modem measuring systems and methods. The measured value is roundness, one of the basic shapes of cross section in mechanical engineering. This paper arises in search of answers for the question whether conventional measuring techniques and equipments are made redundant because of the modern ones. In what segments and in which criterion are modem methods preferable？
基金the Joint Guidance Project of Natural Science Foundation of Heilongjiang Province(No.LH2021F008)。
文摘Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle,so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle.By extracting the direct current(DC)component and the alternating current(AC)component of the light intensity signal detected by the photoelectric detector(PD),the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components,and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform.The experimental results show that the relative error of current measurement does not exceed 1.40%in the current range of 0.05—0.50 A,which is less than the approximate linear measurement(ALM)method,and the magnetic rotation angle and the current have a good linear relationship.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11175108, U1432119, 1146114100, 11205075, 11375076 and 11475104)the Shandong Natural Science Foundation (Grant No. ZR2014AQ012)the Young Scholars Program of Shandong University, Weihai (Grant No. 2015WHWLJH01)
文摘We study the dimensionless spin parameter j ≡ cJ/（GM2） of different kinds of uniformly rotating compact stars, including traditional neutron stars, hyperonic neutron stars and hybrid stars, based on relativistic mean field theory and the MIT bag model. It is found that j ~ 0.7, which had been suggested in traditional neutron stars, is sustained for hyperonic neutron stars and hybrid stars with M 〉 0.5 MG. Not the interior but rather the crust structure of the stars is a key factor to determine jmax for three kinds of selected compact stars. Furthermore, a universal formula j = 0.63（f/fK） -- 0.42（f/fK）2 ＋ 0.48（f/fK）z is suggested to determine the spin parameter at any rotational frequency f smaller than the Keplerian frequency fK.
基金sponsored by the Ministry of Science and Tech-nology under the grant 2007DFA41320the Ministry of Financeunder the grant ZDYZ2008-2+1 种基金National Key Science and Tech-nology Project under the grant 2008ZX05014-003-006HZthe National Natural Science Foundation of China under theGrant 20821092
文摘Real-time simulation of industrial equipment is a huge challenge nowadays. The high performance and fine-grained parallel computing provided by graphics processing units （GPUs） bring us closer to our goals. In this article, an industrial-scale rotating drum is simulated using simplified discrete element method （DEM） without consideration of the tangential components of contact force and particle rotation. A single GPU is used first to simulate a small model system with about 8000 particles in real-time, and the simulation is then scaled up to industrial scale using more than 200 GPUs in a 1 D domain-decomposition parallelization mode. The overall speed is about 1/11 of the real-time. Optimization of the communication part of the parallel GPU codes can speed up the simulation further, indicating that such real-time simulations have not only methodological but also industrial implications in the near future.
基金supported by the National Natural Science Foundations of China (Nos.61371169,61601167, 61601504)the Natural Science Foundation of Jiangsu Province (No.BK20161489)+1 种基金the Open Research Fund of State Key Laboratory of Millimeter Waves, Southeast University (No. K201826)the Fundamental Research Funds for the Central Universities (No. NE2017103)
文摘This paper presents a low?complexity method for the direction?of?arrival(DOA)estimation of noncircular signals for coprime sensor arrays.The noncircular property is exploited to improve the performance of DOA estimation.To reduce the computational complexity,the rotational invariance propagator method(RIPM)is included in the algorithm.First,the extended array output is reconstructed by combining the array output and its conjugated counterpart.Then,the RIPM is utilized to obtain two sets of DOA estimates for two subarrays.Finally,the true DOAs are estimated by combining the consistent results of the two subarrays.This illustrates the potential gain that both noncircularity and coprime arrays provide when considered together.The proposed algorithm has a lower computational complexity and a better DOA estimation performance than the standard estimation of signal parameters by the rotational invariance technique and Capon algorithm.Numerical simulation results illustrate the effectiveness and superiority of the proposed algorithm.
文摘Segregation and mixing of granular materials are complex processes and are not fully understood. Motivated by industrial need, we performed a simulation using the discrete element method to study size segregation of a binary mixture of granular particles in a horizontal rotating drum. Particles of two dif- ferent sizes were poured into the drum until it was 50% full. Shear-driven segregation was induced by rotating the side-plates of the drum in the opposite direction to that of the cylindrical wall. We found that radial segregation diminished in these systems but did not completely vanish. In an ordinary rotating drum, a radial core of smaller particles is formed in the center of the drum, surrounded by larger revolving particles. In our system, however, the smaller particles were found to migrate toward the side-plates. The shear from anti-spinning side-plates reduces the voidage and increases the bulk density. As such, smaller particles in the mixer tend to move to denser regions. We varied the shear by changing the coefficient of friction on the side-plates to study the influence of shear rate on this migration. We also compared the extent of radial segregation with stationary side-plates and with side-plates moving in different angular directions.
基金co-supported by the National Science Foundation of China(No.11222215)the National Basic Research Program of China(No.2013CB733100)
文摘Ideal proportional navigation （IPN） is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation. The closed-form solution of two- dimensional ideal proportional navigation was conducted in previous public literature, whereas the practical interception happens in the three-dimensional space. A novel set of relative dynamic equations is adopted in this paper, which is with the advantage of decoupling relative motion in the instantaneous rotation plane of the line of sight from the rotation of this plane. The dimension-reduced IPN is constructed in this instantaneous plane, which functions as a three-dimensional guidance law. The trajectory features of dimension-reduced IPN are explored, and the capture regions of dimension-reduced IPN with limited acceleration against nonmaneuvering and maneuvering targets are analyzed by using phase plane method. It is proved that the capture capability of IPN is much stronger than true proportional navigation （TPN）, no matter the target maneuvers or not. Finally, simulation results indicate that IPN is more effective than TPN in exoatmospheric interception scenarios.
基金Supported by the National Natural Science Foundation of China (1057115610871173)
文摘In this paper,the parameterized Marcinkiewicz integrals with variable kernels defined by μΩ^ρ（f）（x）=（∫0^∞│∫│1-y│≤t Ω（x,x-y）/│x-y│^n-p f（y）dy│^2dt/t1＋2p）^1/2 are investigated.It is proved that if Ω∈ L∞（R^n） × L^r（S^n-1）（r〉（n-n1p＇/n） is an odd function in the second variable y,then the operator μΩ^ρ is bounded from L^p（R^n） to L^p（R^n） for 1 〈 p ≤ max{（n＋1）/2,2}.It is also proved that,if Ω satisfies the L^1-Dini condition,then μΩ^ρ is of type（p,p） for 1 〈 p ≤ 2,of the weak type（1,1） and bounded from H1 to L1.
基金supported by the National Defense Fundamental Research Foundation of China(grant No.JCKY2023204C033).
文摘Hot isostatic pressing(HIP)is a critical powder metallurgy technique for manufacturing high-performance components.However,achieving uniform powder distribution within complex capsules is challenging,particularly in critical low-density regions where inadequate powder filling leads to non-uniform deformation and potential part rejection after HIP.This study investigated the powder filling and packing densification behavior of Ti-6Al-4V particles through discrete element method(DEM)simulations to develop an enhanced densification technique targeting these critical regions.A new rotational centrifugal method was proposed to address this challenge.Results demonstrated that vertical vibration achieved limited improvement,and horizontal vibration exhibited non-uniform powder distribution.The proposed rotational centrifugal method at 200 rpm proved most effective,achieving the highest relative density with superior uniformity and rapid densification.The analysis in rotational motion revealed that rapid densification originates from consistent centrifugal forces.Upon stopping rotation,particles undergo localized vigorous motion,resulting in a slight decrease in relative density.To address this,an optimized deceleration scheme was developed.It achieved a relative density of 0.549,representing improvements of 70.5%over vertical vibration and 4.2%over horizontal vibration.These findings provide valuable insights for optimizing pre-HIP processing parameters for complex components,offering a promising solution for addressing powder filling challenges.
基金Supported by the National Natural Science Foundation of China(51907061)Natural Science Foundation of Hunan Province(2018JJ2100,2019JJ50119).
文摘Aiming at resolving the limitation of the speed regulation range of sensorless control technology,a new composite sensorless control strategy is proposed to realize a control method for a permanent magnet synchronous motor(PMSM)in full speed range.In the medium-and high-speed range,the improved new sliding mode observer method is used to estimate the motor speed and rotor position information.In the zero and low speed range,in order to avoid the defects of the sliding mode method,the rotating high-frequency voltage signal injection method is used.When switching between low,medium,and high speed,the fuzzy control algorithm is adopted to achieve smooth transitions.The simulation experiment results show that the hybrid mode combining the sliding mode observer and rotating high-frequency voltage injection methods,can effectively reduce the jitter in the algorithm switching process,and realize the smooth control of a PMSM in full speed range.
文摘Aim:This paper addresses the assessment of the composition of a general wound,in terms of all identifiable categories of tissue and pigmentation in an attempt to improve accuracy in assessing and monitoring wound health.Materials and Methods:A knowledgebase of clusters was built into the hue,saturation and intensity(HSI)color space and then used for assessing wound composition.Based on the observation that the clusters are fairly distinct,two different algorithms,that is,Mahalanobis distance(MD)based and the rotated coordinate system(RCS)method,were used for classification.These methods exploit the shape,spread,and orientation of each cluster.Results:The clusters in the HSI color space,built from about 9,000(calibrated)pixels from 48 images of various wound beds,showed 8 fairly distinct regions.The inter-cluster distances were consistent with the visual appearance.The efficacy of the MD and RCS based methods in 120 experiments taken from a set of 15 test images(in terms of average percent-match)was found to be 91.55 and 93.71,respectively.Conclusion:Our investigations established eight categories of tissue and pigmentation in wound beds.These findings help to determine the stage of wound healing more accurately and comprehensively than typically permitted through use of the 4-color model reported in the literature for addressing specific wound types.
