Inverse synthetic aperture radar (ISAR) imaging for maneuvering targets suffers from a Doppler fr... more Inverse synthetic aperture radar (ISAR) imaging for maneuvering targets suffers from a Doppler frequency time-varying problem, leading to the ISAR images blurred in the azimuth direction. Given that the traditional imaging methods have poor imaging performance or low efficiency, and the existing deep learning imaging methods cannot effectively reconstruct the deblurred ISAR images retaining rich details and textures, an unblurring ISAR imaging method based on an advanced Transformer structure for maneuvering targets is proposed. We first present a pseudo-measured data generation method based on the DeepLabv3+ network and Diamond-Square algorithm to acquire an ISAR dataset for training with good generalization to measured data. Next, with the locally-enhanced window Transformer block adopted to enhance the ability to capture local context as well as global dependencies, we construct a novel Uformer-based GAN (UFGAN) to restore the deblurred ISAR images with rich details and textures ...
In this paper, a fractional-order model of the gas film is proposed for the dynamic characteristi... more In this paper, a fractional-order model of the gas film is proposed for the dynamic characteristics of an air bearing. Based on the dynamic characteristics common between gas film and viscoelastic body, the idea of the fractional-order equivalent modeling of the dynamic characteristics of the gas film is presented to improve the modeling accuracy. Four fractional-order gas film (FOGF) models are introduced based on generalization of traditional viscoelastic models. The analysis of the characteristics of the FOGF models shows that the FOGF model can capture more complex dynamic characteristics and fit the real dynamic data of the gas film better than traditional models. A genetic algorithm particle swarm optimization (GA-PSO) method is used for parameter identification of the proposed models. The experimental results tested on the air bearing motion platform show that the FOGF models are superior in accuracy to the traditional equivalent models for the gas film. In particular, the fr...
The micro-motion target echoes can be regarded as the accumulation of a few strong scattering poi... more The micro-motion target echoes can be regarded as the accumulation of a few strong scattering points echoes, which are naturally sparse. Therefore, the compressed sensing (CS) reconstruction method can be used to analyze the incomplete micro-Doppler signal and extract the micro-motion features. Traditional CS reconstruction algorithms are time-consuming and sensitive to the selection of model parameters, limiting the performance of micro-motion feature extraction. This paper proposes a deep unfolded method to achieve the reconstruction of the time-frequency representation (TFR) of incomplete micro-Doppler signals. First, the joint time-frequency (JTF) transform is used to construct the CS model and the Training data is obtained according to the model. Then, the alternating direction method of multipliers (ADMM) algorithm is constructed into an iterative network named ADMM-net corresponding to the iterative solution process. An auxiliary loss is designed into the ADMM-net called AL-ADMM-net to improve the quality of reconstruction. The AL-ADMM-net is trained by the training data to learn the optimal parameters. Furthermore, an AL-ADMM-net iterative method is proposed when the micro-Doppler signal has phase corruption. Simulations are given to prove the effectiveness of the proposed method. INDEX TERMS Compressed sensing, micro-doppler, ADMM-net, deep learning, auxiliary loss.
The ground moving target (GMT) is defocused due to unknown motion parameters in synthetic apertur... more The ground moving target (GMT) is defocused due to unknown motion parameters in synthetic aperture radar (SAR) imaging. Although the conventional Omega-K algorithm (Omega-KA) has been proven to be applicable for GMT imaging, its disadvantages are slow imaging speed, obvious sidelobe interference, and high computational complexity. To solve the above problems, a SAR-GMT imaging network is proposed based on trainable Omega-KA and sparse optimization. Specifically, we propose a two-dimensional (2-D) sparse imaging model deducted from the Omega-KA focusing process. Then, a recurrent neural network (RNN) based on an iterative optimization algorithm is built to learn the trainable parameters of Omega-KA by an off-line supervised training method, and the solving process of the sparse imaging model is mapped to each layer of the RNN. The proposed trainable Omega-KA network (Omega-KA-net) forms a new GMT imaging method that can be applied to high-quality imaging under down-sampling and a low...
In order to achieve low-cost, non-radiation imaging inspection of lithium-ion pouch cell, a new i... more In order to achieve low-cost, non-radiation imaging inspection of lithium-ion pouch cell, a new in situ imaging detection method based on guided waves for thin lithium-ion pouch cell was proposed in this paper. According to the propagation theory of ultrasonic guided wave in plate, the propagation of guided waves in a thin lithium-ion pouch cell was analyzed. A guided wave imaging detection system for lithium-ion pouch cell was built up and a pouch cell lithium-ion battery with a thickness of 3.5 mm in a fully charged state was used as the specimen. A piezoelectric transducer was used to excite guided waves, and a scanning laser Doppler vibrometer (SLDV) was used to collect three-dimensional wave field matrix. In the obtained transient guided wave field diagram, there were phenomena such as wavefront lag, irregular patterns, and scattered irregular dots, and a defect of size 22 × 18 mm2 was also identified. Analysis of the mode conversion during the guided wave propagation in the battery reveals that the energy spectrum imaging of main mode can achieve the same effect as the transient guided wave imaging, and reduces the time of the selection moment. The imaging detection method in this paper was the first attempt of ultrasonic guided wave in the in situ imaging of lithium-ion battery.
A piecewise frequency control (PFC) strategy is proposed in this paper for coordinating vibration... more A piecewise frequency control (PFC) strategy is proposed in this paper for coordinating vibration isolation and positioning of supporting systems under complex disturbance conditions, such as direct and external disturbances. This control strategy is applied in an active-passive parallel supporting system, where relative positioning feedback for positioning and absolute velocity feedback for active vibration isolation. The analysis of vibration and deformation transmissibility shows that vibration control increases low-frequency position error while positioning control amplifies high-frequency vibration amplitude. To overcome this contradiction across the whole control bandwidth, a pair of Fractional-Order Filters (FOFs) is adopted in the PFC system, which increases the flexibility in the PFC design by introducing fraction orders. The system stability analysis indicates that the FOFs can provide a better stability margin than the Integral-Order Filters (IOFs), so the control gains a...
The vortex electromagnetic wave radar based on monostatic geometry can realize the imaging of a r... more The vortex electromagnetic wave radar based on monostatic geometry can realize the imaging of a radar target in both range dimension and azimuth dimension by adjusting vortex electromagnetic wave modes, but it has no ability to distinguish the elevation of the radar target. To achieve three-dimensional imaging of the radar target, a three-dimensional imaging method of vortex electromagnetic wave based on bistatic geometry is proposed. The echo model of the target based on vortex electromagnetic wave in bistatic geometry is constructed firstly. The elevation resolution of the target is realized, and then the three-dimensional coordinate of the target is reconstructed. Moreover, the elevation resolution and the computational complexity of the proposed method are also analyzed. Simulation results demonstrate the effectiveness of the proposed method. The results also illustrate that the array element requirements and the computational complexity of presented algorithm are less than Mult...
The sealing system performance of a nuclear reactor pressure vessel (RPV) under different working... more The sealing system performance of a nuclear reactor pressure vessel (RPV) under different working circumstances is vital to the safe operation of the whole nuclear process; however, the mechanism, and especially the relationship among highly related variables for it, has remained unclear. Therefore, a new inconsistent knowledge fused Bayesian network and weighted loss function (iBWL) method was proposed to identify key variables and estimate the reliability of an RPV sealing system. In this method, a new inconsistent knowledge fusion method was proposed to make good use of available priceless field knowledge by considering its reliability and inconsistency seriously. The key variables identified by the Bayesian network structure were then used by a new weighted loss function to estimate the reliability of the RPV sealing system by comprehensively quantifying the deviations of them from their corresponding expected values. It is not only the quantified reliability of RPV sealing that...
Micro-Doppler is regarded as a unique signature of a target with micro-motions. The sophisticated... more Micro-Doppler is regarded as a unique signature of a target with micro-motions. The sophisticated recognition of the cone-shaped targets can be realized through the micro-Doppler effect. However, it is difficult to extract the micro-motion features perpendicular to the radar line of sight (LOS) effectively. In this paper, a micro-Doppler parameters extraction method of the cone-shaped targets is put forward based on the rotating antenna. First, a new radar configuration is proposed, in which an antenna rotates uniformly on a fixed circle, thus producing Doppler frequency shift. Second, the expression of the micro-Doppler frequency shift induced by the precession cone-shaped target is derived. Then, the micro-Doppler curves of point scatterers at the cone top and bottom are separated by the smoothness of the curves, and the empirical mode decomposition (EMD) method is utilized for the detection and estimation of the coning frequency. Finally, the micro-motion components perpendicular...
To investigate the diversity and structure of soil bacterial and fungal communities in saline soi... more To investigate the diversity and structure of soil bacterial and fungal communities in saline soils, soil samples with three increasing salinity levels (S1, S2 and S3) were collected from a maize field in Yanqi, Xinjiang Province, China. The results showed that the K+, Na+, Ca2+ and Mg2+ values in the bulk soil were higher than those in the rhizosphere soil, with significant differences in S2 and S3 (p < 0.05). The enzyme activities of alkaline phosphatase (ALP), invertase, urease and catalase (CAT) were lower in the bulk soil than those in the rhizosphere. Principal coordinate analysis (PCoA) demonstrated that the soil microbial community structure exhibited significant differences between different salinized soils (p < 0.001). Data implied that the fungi were more susceptible to salinity stress than the bacteria based on the Shannon and Chao1 indexes. Mantel tests identified Ca2+, available phosphorus (AP), saturated electrical conductivity (ECe) and available kalium (AK) as...
Hypoxia can lead to stabilization of the tumor suppressor gene p53 and cell death. However, p53 m... more Hypoxia can lead to stabilization of the tumor suppressor gene p53 and cell death. However, p53 mutations could promote cell survival in a hypoxic environment. In this study, we found that p53N236S (p53N239S in humans, hereinafter referred to as p53S) mutant mouse embryonic fibroblasts (MEFs) resistant to deferoxamine (DFO) mimic a hypoxic environment. Further, Western blot and flow cytometry showed reduced apoptosis in p53S/S cells compared to WT after DFO treatment, suggesting an antiapoptosis function of p53S mutation in response to hypoxia-mimetic DFO. Instead, p53S/S cells underwent autophagy in response to hypoxia stress presumably through inhibition of the AKT/mTOR pathway, and this process was coupled with nuclear translocation of p53S protein. To understand the relationship between autophagy and apoptosis in p53S/S cells in response to hypoxia, the autophagic inhibitor 3-MA was used to treat both WT and p53S/S cells after DFO exposure. Both apoptotic signaling and cell deat...
In this paper, the design of a fractional-order proportional integral (FOPI) controller and integ... more In this paper, the design of a fractional-order proportional integral (FOPI) controller and integer-order (IOPI) controller are compared for the permanent magnet synchronous motor (PMSM) speed regulation system. A high-precision implementation method of a fractional-order proportional integral (FOPI) controller is proposed in this work. Three commonly used numerical implementation methods of fractional operators are investigated and compared for comprehensively evaluating the numerical implementation performance in this work. Furthermore, for the impulse response invariant implementation method, the effects of different discretization orders on the control performance of the system are compared. The high-order fractional-order controller can be implemented accurately in a control system with the field-programmable gate array (FPGA) with the capability of parallel calculation. The simulation and experimental results show that the high-precision numerical implementation method of the ...
In this paper, a fractional-order active disturbance rejection controller (FOADRC), combining a f... more In this paper, a fractional-order active disturbance rejection controller (FOADRC), combining a fractional-order proportional derivative (FOPD) controller and an extended state observer (ESO), is proposed for a permanent magnet synchronous motor (PMSM) speed servo system. The global stable region in the parameter (Kp, Kd, μ)-space corresponding to the observer bandwidth ωo can be obtained by D-decomposition method. To achieve a satisfied tracking and anti-load disturbance performance, an optimal ADRC tuning strategy is proposed. This tuning strategy is applicable to both FOADRC and integer-order active disturbance rejection controller (IOADRC). The tuning method not only meets user-specified frequency-domain indicators but also achieves a time-domain performance index. Simulation and experimental results demonstrate that the proposed FOADRC achieves better speed tracking, and more robustness to external disturbance performances than traditional IOADRC and typical Proportional-Integr...
The impact wear resistance of the hard coating is very important in the high-temperature environm... more The impact wear resistance of the hard coating is very important in the high-temperature environment of the nuclear power plant. CrN and CrAlN coatings were prepared using multi-arc ion plating. The impact abrasive wear resistance of the coatings was investigated at varied temperatures through a controlled kinetic energy impact wear rig, and their impact mechanism was elucidated. No extensive spalling was found on the surface of the CrN and CrAlN coatings after 104 impacts under the no-sand condition. The excellent antioxidant properties of the CrN and CrAlN coatings can protect the substrate from oxidation under the no-sand condition at 500 °C. The impact mechanism of the two coatings was plastic deformation under the no-sand condition, and it was mainly material removal under the sand condition. The depth and width of wear scar were larger under the sand condition than under the no-sand condition. The impact wear region was divided into a mixed impact zone and a sand impact zone. ...
Alfalfa (Medicago sativa) is one of the high protein ingredients of fermented total mixed ration ... more Alfalfa (Medicago sativa) is one of the high protein ingredients of fermented total mixed ration (FTMR). Additionally, FTMR is widely used to satisfy the nutrition requirements of animals. This study was conducted to confirm the fermentation characteristics, chemical compositions and protein fractions changes when replacing ensiled-alfalfa with fresh-alfalfa in FTMR with additives. Three additives were separately applied to fresh-alfalfa total mixed ration (TMR) and ensiled-alfalfa TMR, including molasses (MOL), Lactobacillus plantarum (LP) and MOL plus LP (MOL+LP). The same volume of distilled water was sprayed onto the prepared TMR as performed for the control (CK). Each treatment included 18 repetitions and opened 3 repetitions at each fermenting day (1, 3, 7, 15, 30 and 60 d). The results showed that fresh-alfalfa FTMR (F-FTMR) exhibited slight changes in the fermentation characteristics during the first 7 d and showed similar trends in terms of the pH and organic acids content ...
Deep learning has been used in inverse synthetic aperture radar (ISAR) imaging to improve resolut... more Deep learning has been used in inverse synthetic aperture radar (ISAR) imaging to improve resolution performance, but there still exist some problems: the loss of weak scattering points, over-smoothed imaging results, and the universality and generalization. To address these problems, an ISAR resolution enhancement method of exploiting a generative adversarial network (GAN) is proposed in this paper. We adopt a relativistic average discriminator (RaD) to enhance the ability of the network to describe target details. The proposed loss function is composed of feature loss, adversarial loss, and absolute loss. The feature loss is used to get the main characteristics of the target. The adversarial loss ensures that the proposed GAN recovers more target details. The absolute loss is adopted to make the imaging results not over-smoothed. Experiments based on simulated and measured data under different conditions demonstrate that the proposed method has good imaging performance. In additio...
Multilayered ultrasonic welding (USW) is widely used in joining of electrodes or tabs in lithium-... more Multilayered ultrasonic welding (USW) is widely used in joining of electrodes or tabs in lithium-ion batteries. This chapter proposes a localized preheating method to improve the process robustness and studies the effects of preheating temperature on the weld process and performance experimentally and numerically. The experimental results indicate that weld formation can be accelerated and the weld strength can be improved with process preheating, especially at the interface closest to the anvil. The effect of preheating is most significant during the early stage of the process, and diminishes as the process progresses. Numerical models reveal the underlying mechanisms influencing the temperature distribution, workpiece motion, and stress distribution of preheating on the welding process. Preheating improves the robustness of multilayered USW joints.
A manta ray biomimetic glider is designed and studied with both laboratory experiments and numeri... more A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated. The results show that the glider will show the optimal gliding performance when the center of mass is 20mm in front of the center of geometry and the initial attack angle range lies between A0 = -5° to A0 = -2.5° at the same time....
Considering the performance requirements in actual applications, a look-up table based fractional... more Considering the performance requirements in actual applications, a look-up table based fractional order composite control scheme for the permanent magnet synchronous motor speed servo system is proposed. Firstly, an extended state observer based compensation scheme was adopted to suppress the motor parametric uncertainties and convert the speed servo plant into a double-integrator model. Then, a fractional order proportional-derivative (PDμ) controller was adopted as the speed controller to provide the optimal step response performance for the servo system. A universal look-up table was established to estimate the derivative order of the PDμ controller, according to the optimal samples collected by an improved differential evolution algorithm. With the look-up table, the optimal PDμ controller can be tuned analytically. Simulation and experimental results show that the servo system using the composite control scheme can achieve optimal tracking performance and has robustness to the ...
The impact wear property of hard coatings at elevated temperatures is of particular interest for ... more The impact wear property of hard coatings at elevated temperatures is of particular interest for applications in nuclear power plants. This study evaluated the impact wear behavior of two CrAlN/TiSiN coatings with and without sand. Alternately grown CrAlN and TiSiN films with modulation periods of 455 and 19 nm were formed in a columnar structure. The nanomultilayer shows better impact wear resistance than multilayer films with and without sand. The energy absorption rate has a similar trend to wear rate, leading to lower rebound velocity and peak impact force of the nanomultilayer compared with that of the multilayer. CrAlN/TiSiN coatings can protect the 308L substrate from oxidation. The dominant impact wear mechanism without sand is plastic deformation, and this wear region can be defined as the percussive zone. Peeling occurs on the multilayer surface without sand after 104 percussions, leading to rapid oxidation of the 308L substrate at 500 °C. Due to the abrasion effect, the w...
Inverse synthetic aperture radar (ISAR) imaging for maneuvering targets suffers from a Doppler fr... more Inverse synthetic aperture radar (ISAR) imaging for maneuvering targets suffers from a Doppler frequency time-varying problem, leading to the ISAR images blurred in the azimuth direction. Given that the traditional imaging methods have poor imaging performance or low efficiency, and the existing deep learning imaging methods cannot effectively reconstruct the deblurred ISAR images retaining rich details and textures, an unblurring ISAR imaging method based on an advanced Transformer structure for maneuvering targets is proposed. We first present a pseudo-measured data generation method based on the DeepLabv3+ network and Diamond-Square algorithm to acquire an ISAR dataset for training with good generalization to measured data. Next, with the locally-enhanced window Transformer block adopted to enhance the ability to capture local context as well as global dependencies, we construct a novel Uformer-based GAN (UFGAN) to restore the deblurred ISAR images with rich details and textures ...
In this paper, a fractional-order model of the gas film is proposed for the dynamic characteristi... more In this paper, a fractional-order model of the gas film is proposed for the dynamic characteristics of an air bearing. Based on the dynamic characteristics common between gas film and viscoelastic body, the idea of the fractional-order equivalent modeling of the dynamic characteristics of the gas film is presented to improve the modeling accuracy. Four fractional-order gas film (FOGF) models are introduced based on generalization of traditional viscoelastic models. The analysis of the characteristics of the FOGF models shows that the FOGF model can capture more complex dynamic characteristics and fit the real dynamic data of the gas film better than traditional models. A genetic algorithm particle swarm optimization (GA-PSO) method is used for parameter identification of the proposed models. The experimental results tested on the air bearing motion platform show that the FOGF models are superior in accuracy to the traditional equivalent models for the gas film. In particular, the fr...
The micro-motion target echoes can be regarded as the accumulation of a few strong scattering poi... more The micro-motion target echoes can be regarded as the accumulation of a few strong scattering points echoes, which are naturally sparse. Therefore, the compressed sensing (CS) reconstruction method can be used to analyze the incomplete micro-Doppler signal and extract the micro-motion features. Traditional CS reconstruction algorithms are time-consuming and sensitive to the selection of model parameters, limiting the performance of micro-motion feature extraction. This paper proposes a deep unfolded method to achieve the reconstruction of the time-frequency representation (TFR) of incomplete micro-Doppler signals. First, the joint time-frequency (JTF) transform is used to construct the CS model and the Training data is obtained according to the model. Then, the alternating direction method of multipliers (ADMM) algorithm is constructed into an iterative network named ADMM-net corresponding to the iterative solution process. An auxiliary loss is designed into the ADMM-net called AL-ADMM-net to improve the quality of reconstruction. The AL-ADMM-net is trained by the training data to learn the optimal parameters. Furthermore, an AL-ADMM-net iterative method is proposed when the micro-Doppler signal has phase corruption. Simulations are given to prove the effectiveness of the proposed method. INDEX TERMS Compressed sensing, micro-doppler, ADMM-net, deep learning, auxiliary loss.
The ground moving target (GMT) is defocused due to unknown motion parameters in synthetic apertur... more The ground moving target (GMT) is defocused due to unknown motion parameters in synthetic aperture radar (SAR) imaging. Although the conventional Omega-K algorithm (Omega-KA) has been proven to be applicable for GMT imaging, its disadvantages are slow imaging speed, obvious sidelobe interference, and high computational complexity. To solve the above problems, a SAR-GMT imaging network is proposed based on trainable Omega-KA and sparse optimization. Specifically, we propose a two-dimensional (2-D) sparse imaging model deducted from the Omega-KA focusing process. Then, a recurrent neural network (RNN) based on an iterative optimization algorithm is built to learn the trainable parameters of Omega-KA by an off-line supervised training method, and the solving process of the sparse imaging model is mapped to each layer of the RNN. The proposed trainable Omega-KA network (Omega-KA-net) forms a new GMT imaging method that can be applied to high-quality imaging under down-sampling and a low...
In order to achieve low-cost, non-radiation imaging inspection of lithium-ion pouch cell, a new i... more In order to achieve low-cost, non-radiation imaging inspection of lithium-ion pouch cell, a new in situ imaging detection method based on guided waves for thin lithium-ion pouch cell was proposed in this paper. According to the propagation theory of ultrasonic guided wave in plate, the propagation of guided waves in a thin lithium-ion pouch cell was analyzed. A guided wave imaging detection system for lithium-ion pouch cell was built up and a pouch cell lithium-ion battery with a thickness of 3.5 mm in a fully charged state was used as the specimen. A piezoelectric transducer was used to excite guided waves, and a scanning laser Doppler vibrometer (SLDV) was used to collect three-dimensional wave field matrix. In the obtained transient guided wave field diagram, there were phenomena such as wavefront lag, irregular patterns, and scattered irregular dots, and a defect of size 22 × 18 mm2 was also identified. Analysis of the mode conversion during the guided wave propagation in the battery reveals that the energy spectrum imaging of main mode can achieve the same effect as the transient guided wave imaging, and reduces the time of the selection moment. The imaging detection method in this paper was the first attempt of ultrasonic guided wave in the in situ imaging of lithium-ion battery.
A piecewise frequency control (PFC) strategy is proposed in this paper for coordinating vibration... more A piecewise frequency control (PFC) strategy is proposed in this paper for coordinating vibration isolation and positioning of supporting systems under complex disturbance conditions, such as direct and external disturbances. This control strategy is applied in an active-passive parallel supporting system, where relative positioning feedback for positioning and absolute velocity feedback for active vibration isolation. The analysis of vibration and deformation transmissibility shows that vibration control increases low-frequency position error while positioning control amplifies high-frequency vibration amplitude. To overcome this contradiction across the whole control bandwidth, a pair of Fractional-Order Filters (FOFs) is adopted in the PFC system, which increases the flexibility in the PFC design by introducing fraction orders. The system stability analysis indicates that the FOFs can provide a better stability margin than the Integral-Order Filters (IOFs), so the control gains a...
The vortex electromagnetic wave radar based on monostatic geometry can realize the imaging of a r... more The vortex electromagnetic wave radar based on monostatic geometry can realize the imaging of a radar target in both range dimension and azimuth dimension by adjusting vortex electromagnetic wave modes, but it has no ability to distinguish the elevation of the radar target. To achieve three-dimensional imaging of the radar target, a three-dimensional imaging method of vortex electromagnetic wave based on bistatic geometry is proposed. The echo model of the target based on vortex electromagnetic wave in bistatic geometry is constructed firstly. The elevation resolution of the target is realized, and then the three-dimensional coordinate of the target is reconstructed. Moreover, the elevation resolution and the computational complexity of the proposed method are also analyzed. Simulation results demonstrate the effectiveness of the proposed method. The results also illustrate that the array element requirements and the computational complexity of presented algorithm are less than Mult...
The sealing system performance of a nuclear reactor pressure vessel (RPV) under different working... more The sealing system performance of a nuclear reactor pressure vessel (RPV) under different working circumstances is vital to the safe operation of the whole nuclear process; however, the mechanism, and especially the relationship among highly related variables for it, has remained unclear. Therefore, a new inconsistent knowledge fused Bayesian network and weighted loss function (iBWL) method was proposed to identify key variables and estimate the reliability of an RPV sealing system. In this method, a new inconsistent knowledge fusion method was proposed to make good use of available priceless field knowledge by considering its reliability and inconsistency seriously. The key variables identified by the Bayesian network structure were then used by a new weighted loss function to estimate the reliability of the RPV sealing system by comprehensively quantifying the deviations of them from their corresponding expected values. It is not only the quantified reliability of RPV sealing that...
Micro-Doppler is regarded as a unique signature of a target with micro-motions. The sophisticated... more Micro-Doppler is regarded as a unique signature of a target with micro-motions. The sophisticated recognition of the cone-shaped targets can be realized through the micro-Doppler effect. However, it is difficult to extract the micro-motion features perpendicular to the radar line of sight (LOS) effectively. In this paper, a micro-Doppler parameters extraction method of the cone-shaped targets is put forward based on the rotating antenna. First, a new radar configuration is proposed, in which an antenna rotates uniformly on a fixed circle, thus producing Doppler frequency shift. Second, the expression of the micro-Doppler frequency shift induced by the precession cone-shaped target is derived. Then, the micro-Doppler curves of point scatterers at the cone top and bottom are separated by the smoothness of the curves, and the empirical mode decomposition (EMD) method is utilized for the detection and estimation of the coning frequency. Finally, the micro-motion components perpendicular...
To investigate the diversity and structure of soil bacterial and fungal communities in saline soi... more To investigate the diversity and structure of soil bacterial and fungal communities in saline soils, soil samples with three increasing salinity levels (S1, S2 and S3) were collected from a maize field in Yanqi, Xinjiang Province, China. The results showed that the K+, Na+, Ca2+ and Mg2+ values in the bulk soil were higher than those in the rhizosphere soil, with significant differences in S2 and S3 (p < 0.05). The enzyme activities of alkaline phosphatase (ALP), invertase, urease and catalase (CAT) were lower in the bulk soil than those in the rhizosphere. Principal coordinate analysis (PCoA) demonstrated that the soil microbial community structure exhibited significant differences between different salinized soils (p < 0.001). Data implied that the fungi were more susceptible to salinity stress than the bacteria based on the Shannon and Chao1 indexes. Mantel tests identified Ca2+, available phosphorus (AP), saturated electrical conductivity (ECe) and available kalium (AK) as...
Hypoxia can lead to stabilization of the tumor suppressor gene p53 and cell death. However, p53 m... more Hypoxia can lead to stabilization of the tumor suppressor gene p53 and cell death. However, p53 mutations could promote cell survival in a hypoxic environment. In this study, we found that p53N236S (p53N239S in humans, hereinafter referred to as p53S) mutant mouse embryonic fibroblasts (MEFs) resistant to deferoxamine (DFO) mimic a hypoxic environment. Further, Western blot and flow cytometry showed reduced apoptosis in p53S/S cells compared to WT after DFO treatment, suggesting an antiapoptosis function of p53S mutation in response to hypoxia-mimetic DFO. Instead, p53S/S cells underwent autophagy in response to hypoxia stress presumably through inhibition of the AKT/mTOR pathway, and this process was coupled with nuclear translocation of p53S protein. To understand the relationship between autophagy and apoptosis in p53S/S cells in response to hypoxia, the autophagic inhibitor 3-MA was used to treat both WT and p53S/S cells after DFO exposure. Both apoptotic signaling and cell deat...
In this paper, the design of a fractional-order proportional integral (FOPI) controller and integ... more In this paper, the design of a fractional-order proportional integral (FOPI) controller and integer-order (IOPI) controller are compared for the permanent magnet synchronous motor (PMSM) speed regulation system. A high-precision implementation method of a fractional-order proportional integral (FOPI) controller is proposed in this work. Three commonly used numerical implementation methods of fractional operators are investigated and compared for comprehensively evaluating the numerical implementation performance in this work. Furthermore, for the impulse response invariant implementation method, the effects of different discretization orders on the control performance of the system are compared. The high-order fractional-order controller can be implemented accurately in a control system with the field-programmable gate array (FPGA) with the capability of parallel calculation. The simulation and experimental results show that the high-precision numerical implementation method of the ...
In this paper, a fractional-order active disturbance rejection controller (FOADRC), combining a f... more In this paper, a fractional-order active disturbance rejection controller (FOADRC), combining a fractional-order proportional derivative (FOPD) controller and an extended state observer (ESO), is proposed for a permanent magnet synchronous motor (PMSM) speed servo system. The global stable region in the parameter (Kp, Kd, μ)-space corresponding to the observer bandwidth ωo can be obtained by D-decomposition method. To achieve a satisfied tracking and anti-load disturbance performance, an optimal ADRC tuning strategy is proposed. This tuning strategy is applicable to both FOADRC and integer-order active disturbance rejection controller (IOADRC). The tuning method not only meets user-specified frequency-domain indicators but also achieves a time-domain performance index. Simulation and experimental results demonstrate that the proposed FOADRC achieves better speed tracking, and more robustness to external disturbance performances than traditional IOADRC and typical Proportional-Integr...
The impact wear resistance of the hard coating is very important in the high-temperature environm... more The impact wear resistance of the hard coating is very important in the high-temperature environment of the nuclear power plant. CrN and CrAlN coatings were prepared using multi-arc ion plating. The impact abrasive wear resistance of the coatings was investigated at varied temperatures through a controlled kinetic energy impact wear rig, and their impact mechanism was elucidated. No extensive spalling was found on the surface of the CrN and CrAlN coatings after 104 impacts under the no-sand condition. The excellent antioxidant properties of the CrN and CrAlN coatings can protect the substrate from oxidation under the no-sand condition at 500 °C. The impact mechanism of the two coatings was plastic deformation under the no-sand condition, and it was mainly material removal under the sand condition. The depth and width of wear scar were larger under the sand condition than under the no-sand condition. The impact wear region was divided into a mixed impact zone and a sand impact zone. ...
Alfalfa (Medicago sativa) is one of the high protein ingredients of fermented total mixed ration ... more Alfalfa (Medicago sativa) is one of the high protein ingredients of fermented total mixed ration (FTMR). Additionally, FTMR is widely used to satisfy the nutrition requirements of animals. This study was conducted to confirm the fermentation characteristics, chemical compositions and protein fractions changes when replacing ensiled-alfalfa with fresh-alfalfa in FTMR with additives. Three additives were separately applied to fresh-alfalfa total mixed ration (TMR) and ensiled-alfalfa TMR, including molasses (MOL), Lactobacillus plantarum (LP) and MOL plus LP (MOL+LP). The same volume of distilled water was sprayed onto the prepared TMR as performed for the control (CK). Each treatment included 18 repetitions and opened 3 repetitions at each fermenting day (1, 3, 7, 15, 30 and 60 d). The results showed that fresh-alfalfa FTMR (F-FTMR) exhibited slight changes in the fermentation characteristics during the first 7 d and showed similar trends in terms of the pH and organic acids content ...
Deep learning has been used in inverse synthetic aperture radar (ISAR) imaging to improve resolut... more Deep learning has been used in inverse synthetic aperture radar (ISAR) imaging to improve resolution performance, but there still exist some problems: the loss of weak scattering points, over-smoothed imaging results, and the universality and generalization. To address these problems, an ISAR resolution enhancement method of exploiting a generative adversarial network (GAN) is proposed in this paper. We adopt a relativistic average discriminator (RaD) to enhance the ability of the network to describe target details. The proposed loss function is composed of feature loss, adversarial loss, and absolute loss. The feature loss is used to get the main characteristics of the target. The adversarial loss ensures that the proposed GAN recovers more target details. The absolute loss is adopted to make the imaging results not over-smoothed. Experiments based on simulated and measured data under different conditions demonstrate that the proposed method has good imaging performance. In additio...
Multilayered ultrasonic welding (USW) is widely used in joining of electrodes or tabs in lithium-... more Multilayered ultrasonic welding (USW) is widely used in joining of electrodes or tabs in lithium-ion batteries. This chapter proposes a localized preheating method to improve the process robustness and studies the effects of preheating temperature on the weld process and performance experimentally and numerically. The experimental results indicate that weld formation can be accelerated and the weld strength can be improved with process preheating, especially at the interface closest to the anvil. The effect of preheating is most significant during the early stage of the process, and diminishes as the process progresses. Numerical models reveal the underlying mechanisms influencing the temperature distribution, workpiece motion, and stress distribution of preheating on the welding process. Preheating improves the robustness of multilayered USW joints.
A manta ray biomimetic glider is designed and studied with both laboratory experiments and numeri... more A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated. The results show that the glider will show the optimal gliding performance when the center of mass is 20mm in front of the center of geometry and the initial attack angle range lies between A0 = -5° to A0 = -2.5° at the same time....
Considering the performance requirements in actual applications, a look-up table based fractional... more Considering the performance requirements in actual applications, a look-up table based fractional order composite control scheme for the permanent magnet synchronous motor speed servo system is proposed. Firstly, an extended state observer based compensation scheme was adopted to suppress the motor parametric uncertainties and convert the speed servo plant into a double-integrator model. Then, a fractional order proportional-derivative (PDμ) controller was adopted as the speed controller to provide the optimal step response performance for the servo system. A universal look-up table was established to estimate the derivative order of the PDμ controller, according to the optimal samples collected by an improved differential evolution algorithm. With the look-up table, the optimal PDμ controller can be tuned analytically. Simulation and experimental results show that the servo system using the composite control scheme can achieve optimal tracking performance and has robustness to the ...
The impact wear property of hard coatings at elevated temperatures is of particular interest for ... more The impact wear property of hard coatings at elevated temperatures is of particular interest for applications in nuclear power plants. This study evaluated the impact wear behavior of two CrAlN/TiSiN coatings with and without sand. Alternately grown CrAlN and TiSiN films with modulation periods of 455 and 19 nm were formed in a columnar structure. The nanomultilayer shows better impact wear resistance than multilayer films with and without sand. The energy absorption rate has a similar trend to wear rate, leading to lower rebound velocity and peak impact force of the nanomultilayer compared with that of the multilayer. CrAlN/TiSiN coatings can protect the 308L substrate from oxidation. The dominant impact wear mechanism without sand is plastic deformation, and this wear region can be defined as the percussive zone. Peeling occurs on the multilayer surface without sand after 104 percussions, leading to rapid oxidation of the 308L substrate at 500 °C. Due to the abrasion effect, the w...
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