Theory and numerical computation of EM field distribution rule in a biologicalmedium with irregular shape are described. Integral equations of induced EM field distributionin biological body are deduced from EM field ...Theory and numerical computation of EM field distribution rule in a biologicalmedium with irregular shape are described. Integral equations of induced EM field distributionin biological body are deduced from EM field scattering. Numerical computations are conductedby the moment method. In order to verify the effectiveness of the theory, a set of experimentalequipment is designed precisely. The results of numerical computation are compared with mea-sured values. It is shown that they are in good agreement. This theory can be used widely forits generality.展开更多
This paper presents an approach for fully automatic segmentation of MS lesions in fluid attenuated inversion recovery (FLAIR) Magnetic Resonance (MR) images. The proposed method estimates a gaussian mixture model with...This paper presents an approach for fully automatic segmentation of MS lesions in fluid attenuated inversion recovery (FLAIR) Magnetic Resonance (MR) images. The proposed method estimates a gaussian mixture model with three kernels as cerebrospinal fluid (CSF), normal tissue and Multiple Sclerosis lesions. To estimate this model, an automatic Entropy based EM algorithm is used to find the best estimated Model. Then, Markov random field (MRF) model and EM algorithm are utilized to obtain and upgrade the class conditional probability density function and the apriori probability of each class. After estimation of Model parameters and apriori probability, brain tissues are classified using bayesian classification. To evaluate the result of the proposed method, similarity criteria of different slices related to 20 MS patients are calculated and compared with other methods which include manual segmentation. Also, volume of segmented lesions are computed and compared with gold standard using correlation coefficient. The proposed method has better performance in comparison with previous works which are reported here.展开更多
提出一种基于贪心EM算法的HMRF遥感影像变化检测算法。该算法采取PCA与差值法相结合的方式来构造差分影像。首先,采用隐马尔可夫随机场(Hidden Markov Random Field,HMRF)模型描述空间上下文信息,并构造系统能量函数;然后,利用贪心EM算...提出一种基于贪心EM算法的HMRF遥感影像变化检测算法。该算法采取PCA与差值法相结合的方式来构造差分影像。首先,采用隐马尔可夫随机场(Hidden Markov Random Field,HMRF)模型描述空间上下文信息,并构造系统能量函数;然后,利用贪心EM算法克服EM算法假定混合成分数为已知、迭代结果过分依赖初始值、可能收敛到局部最大点或收敛到参数空间边界的缺点,能够准确学习分布模型结构和参数,发现数据对模型的最佳匹配;最后,通过条件迭代模型(Iterated Conditional Modes,ICM)优化算法求解能量函数最优解,获取变化区域。实验结果表明,该算法能够更好地保持影像的结构性,有效去除孤立噪声。展开更多
Energy management strategy (EMS) is the core of the real-time controlalgorithm of the hybrid electric vehicle (HEV). A novel EMS using the logic threshold approach withincorporation of a stand-by optimization algorith...Energy management strategy (EMS) is the core of the real-time controlalgorithm of the hybrid electric vehicle (HEV). A novel EMS using the logic threshold approach withincorporation of a stand-by optimization algorithm is proposed. The aim of it is to minimize theengine fuel consumption and maintain the battery state of charge (SOC) in its operation range, whilesatisfying the vehicle performance and drivability requirements. The hybrid powertrain bench testis carried out to collect data of the engine, motor and battery pack, which are used in the EMS tocontrol the powertrain. Computer simulation model of the HEV is established in the MATLAB/Simulinkenvironment according to the bench test results. Simulation results are presented for behaviors ofthe engine, motor and battery. The proposed EMS is implemented for a real parallel hybrid carcontrol system and validated by vehicle field tests.展开更多
In order to add earthquake monitoring methods and develop new method research,the ELF Network for Earthquake Monitoring selected 30 stations in the Capital Circle and the Sichuan-Yunnan region. Finding electromagnetic...In order to add earthquake monitoring methods and develop new method research,the ELF Network for Earthquake Monitoring selected 30 stations in the Capital Circle and the Sichuan-Yunnan region. Finding electromagnetic field background variation is the basis of distinguishing the seismic electromagnetic anomalies. This paper introduces the data acquisition and selection of the Shexian,Anqiu,Lijiang and Dali stations which have recorded for longer time with better data and are located on the similar latitude. Then we use the natural source electromagnetic field's auto-power spectrum to express the intensity of the electromagnetic field. By using power spectral data of many frequencies in the observation frequency band,after the data pre-processing and sliding average noising,the background variation of extremely low frequency stations and the range ability were acquired.Taking the Baoshan M5. 1 earthquake on October 30,2015 and Dali M5. 0 earthquake on May 18,2016 as examples,the authors analyzed the earthquake electromagnetic anomaly characteristic of ELF stations around the earthquakes.展开更多
An unsupervised change-detection method that considers the spatial contextual information in a log-ratio difference image generated from multitemporal SAR images is proposed. A Markov random filed (MRF) model is parti...An unsupervised change-detection method that considers the spatial contextual information in a log-ratio difference image generated from multitemporal SAR images is proposed. A Markov random filed (MRF) model is particularly employed to exploit statistical spatial correlation of intensity levels among neighboring pixels. Under the assumption of the independency of pixels and mixed Gaussian distribution in the log-ratio difference image, a stochastic and iterative EM-MPM change-detection algorithm based on an MRF model is developed. The EM-MPM algorithm is based on a maximiser of posterior marginals (MPM) algorithm for image segmentation and an expectation-maximum (EM) algorithm for parameter estimation in a completely automatic way. The experiment results obtained on multitemporal ERS-2 SAR images show the effectiveness of the proposed method.展开更多
In this paper,we present a numerical simulation method of electromagnetic(EM)fields induced by a moving ship(EMFMS),which consist of both the shaft-rate EM field and the static EM field.The shaft-rate EM fields in the...In this paper,we present a numerical simulation method of electromagnetic(EM)fields induced by a moving ship(EMFMS),which consist of both the shaft-rate EM field and the static EM field.The shaft-rate EM fields in the frequency domain are first obtained by solving the partial differential equations together with suitable boundary conditions,and then they are transformed into the time domain by using the inverse Fourier transform.Finally,the static fields are added to obtain the EM fields of a moving ship.The effects of the source current intensity and the source position on the EM fields of a moving ship are discussed in detail.A field example of EM response of a moving ship is presented and its characteristics are analyzed.展开更多
Effects of processing variables such as frequency of imposed magnetic field, imposed magnetic flux density, processing time, diameter of inclusions, and value of r 1/δ on the electromagnetic separating(EMS) removal e...Effects of processing variables such as frequency of imposed magnetic field, imposed magnetic flux density, processing time, diameter of inclusions, and value of r 1/δ on the electromagnetic separating(EMS) removal efficiency were analyzed theoretically. The higher the frequency, the wider the range of r 1/δ will be. Removal efficiency reaches the maximum while r 1/δ ranges from 1.5 to 2. And the experimental results on aluminum melt show that higher frequency and magnetic flux density make for higher removal efficiency, matching well with the theoretical results. When f is 15.6 kHz, B e is 0.1 T , and imposed time is 10 s, more than 80% inclusion particles with 6 μm diameter can be removed.展开更多
文摘Theory and numerical computation of EM field distribution rule in a biologicalmedium with irregular shape are described. Integral equations of induced EM field distributionin biological body are deduced from EM field scattering. Numerical computations are conductedby the moment method. In order to verify the effectiveness of the theory, a set of experimentalequipment is designed precisely. The results of numerical computation are compared with mea-sured values. It is shown that they are in good agreement. This theory can be used widely forits generality.
文摘This paper presents an approach for fully automatic segmentation of MS lesions in fluid attenuated inversion recovery (FLAIR) Magnetic Resonance (MR) images. The proposed method estimates a gaussian mixture model with three kernels as cerebrospinal fluid (CSF), normal tissue and Multiple Sclerosis lesions. To estimate this model, an automatic Entropy based EM algorithm is used to find the best estimated Model. Then, Markov random field (MRF) model and EM algorithm are utilized to obtain and upgrade the class conditional probability density function and the apriori probability of each class. After estimation of Model parameters and apriori probability, brain tissues are classified using bayesian classification. To evaluate the result of the proposed method, similarity criteria of different slices related to 20 MS patients are calculated and compared with other methods which include manual segmentation. Also, volume of segmented lesions are computed and compared with gold standard using correlation coefficient. The proposed method has better performance in comparison with previous works which are reported here.
基金This project is supported by Electric Vehicle Key Project of National 863 Program of China (No.2001AA501200, 2001AA501211).
文摘Energy management strategy (EMS) is the core of the real-time controlalgorithm of the hybrid electric vehicle (HEV). A novel EMS using the logic threshold approach withincorporation of a stand-by optimization algorithm is proposed. The aim of it is to minimize theengine fuel consumption and maintain the battery state of charge (SOC) in its operation range, whilesatisfying the vehicle performance and drivability requirements. The hybrid powertrain bench testis carried out to collect data of the engine, motor and battery pack, which are used in the EMS tocontrol the powertrain. Computer simulation model of the HEV is established in the MATLAB/Simulinkenvironment according to the bench test results. Simulation results are presented for behaviors ofthe engine, motor and battery. The proposed EMS is implemented for a real parallel hybrid carcontrol system and validated by vehicle field tests.
基金sponsored by the Youth Fund Project of CEA in 2017(QNJJ201702)
文摘In order to add earthquake monitoring methods and develop new method research,the ELF Network for Earthquake Monitoring selected 30 stations in the Capital Circle and the Sichuan-Yunnan region. Finding electromagnetic field background variation is the basis of distinguishing the seismic electromagnetic anomalies. This paper introduces the data acquisition and selection of the Shexian,Anqiu,Lijiang and Dali stations which have recorded for longer time with better data and are located on the similar latitude. Then we use the natural source electromagnetic field's auto-power spectrum to express the intensity of the electromagnetic field. By using power spectral data of many frequencies in the observation frequency band,after the data pre-processing and sliding average noising,the background variation of extremely low frequency stations and the range ability were acquired.Taking the Baoshan M5. 1 earthquake on October 30,2015 and Dali M5. 0 earthquake on May 18,2016 as examples,the authors analyzed the earthquake electromagnetic anomaly characteristic of ELF stations around the earthquakes.
文摘An unsupervised change-detection method that considers the spatial contextual information in a log-ratio difference image generated from multitemporal SAR images is proposed. A Markov random filed (MRF) model is particularly employed to exploit statistical spatial correlation of intensity levels among neighboring pixels. Under the assumption of the independency of pixels and mixed Gaussian distribution in the log-ratio difference image, a stochastic and iterative EM-MPM change-detection algorithm based on an MRF model is developed. The EM-MPM algorithm is based on a maximiser of posterior marginals (MPM) algorithm for image segmentation and an expectation-maximum (EM) algorithm for parameter estimation in a completely automatic way. The experiment results obtained on multitemporal ERS-2 SAR images show the effectiveness of the proposed method.
基金This study is supported by the Fundamental Research Funds for the Central Universities(No.201861020)the Wenhai Program of Qingdao National Laboratory for Marine Science and Technology(QNLM)(No.2017WH ZZB0201).
文摘In this paper,we present a numerical simulation method of electromagnetic(EM)fields induced by a moving ship(EMFMS),which consist of both the shaft-rate EM field and the static EM field.The shaft-rate EM fields in the frequency domain are first obtained by solving the partial differential equations together with suitable boundary conditions,and then they are transformed into the time domain by using the inverse Fourier transform.Finally,the static fields are added to obtain the EM fields of a moving ship.The effects of the source current intensity and the source position on the EM fields of a moving ship are discussed in detail.A field example of EM response of a moving ship is presented and its characteristics are analyzed.
文摘Effects of processing variables such as frequency of imposed magnetic field, imposed magnetic flux density, processing time, diameter of inclusions, and value of r 1/δ on the electromagnetic separating(EMS) removal efficiency were analyzed theoretically. The higher the frequency, the wider the range of r 1/δ will be. Removal efficiency reaches the maximum while r 1/δ ranges from 1.5 to 2. And the experimental results on aluminum melt show that higher frequency and magnetic flux density make for higher removal efficiency, matching well with the theoretical results. When f is 15.6 kHz, B e is 0.1 T , and imposed time is 10 s, more than 80% inclusion particles with 6 μm diameter can be removed.
