To address the difficulties in fusing multi-mode sensor data for complex industrial machinery, an adaptive deep coupling convolutional auto-encoder (ADCCAE) fusion method was proposed. First, the multi-mode features e...To address the difficulties in fusing multi-mode sensor data for complex industrial machinery, an adaptive deep coupling convolutional auto-encoder (ADCCAE) fusion method was proposed. First, the multi-mode features extracted synchronously by the CCAE were stacked and fed to the multi-channel convolution layers for fusion. Then, the fused data was passed to all connection layers for compression and fed to the Softmax module for classification. Finally, the coupling loss function coefficients and the network parameters were optimized through an adaptive approach using the gray wolf optimization (GWO) algorithm. Experimental comparisons showed that the proposed ADCCAE fusion model was superior to existing models for multi-mode data fusion.展开更多
A new multi-mode resistivity imaging sonde, with toroidal coils as source, can conduct three resistivity measurements: azimuthal resistivity, lateral resistivity, and bit resistivity measurements. Thus, the logging ti...A new multi-mode resistivity imaging sonde, with toroidal coils as source, can conduct three resistivity measurements: azimuthal resistivity, lateral resistivity, and bit resistivity measurements. Thus, the logging time and cost are greatly saved. The toroidal coils are simplified as an extended voltage dipole and the response equations are derived for a homogenous formation. Based on 3D FEM, the depth of investigation(DOI), vertical resolution, circumferential azimuthal capacity, borehole diameter, mud resistivity, thickness of target formation, and the resistivity of the surrounding formation and mud invasion are simulated. The results suggest that the three measurement modes of the new sonde are different in vertical resolutions and DOIs. The circumferential detection ability of the azimuth button depends on the contrast between the anomaly and formation resistivity and the open angle of the anomaly. Whether the borehole is truncated at the bit or not has a great influence on the simulation results. The borehole and mud invasion affect the apparent resistivity in all modes, but the effects of resistivity of surrounding formation and thickness of the target formation are only corrected for lateral resistivity measurement.展开更多
For the multi-mode radar working in the modern electronicbattlefield, different working states of one single radar areprone to being classified as multiple emitters when adoptingtraditional classification methods to p...For the multi-mode radar working in the modern electronicbattlefield, different working states of one single radar areprone to being classified as multiple emitters when adoptingtraditional classification methods to process intercepted signals,which has a negative effect on signal classification. A classificationmethod based on spatial data mining is presented to address theabove challenge. Inspired by the idea of spatial data mining, theclassification method applies nuclear field to depicting the distributioninformation of pulse samples in feature space, and digs out thehidden cluster information by analyzing distribution characteristics.In addition, a membership-degree criterion to quantify the correlationamong all classes is established, which ensures classificationaccuracy of signal samples. Numerical experiments show that thepresented method can effectively prevent different working statesof multi-mode emitter from being classified as several emitters,and achieve higher classification accuracy.展开更多
There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because the...There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because their presumptions are that sampled-data should obey the single Gaussian distribution or non-Gaussian distribution. In order to solve these problems, a novel weighted local standardization(WLS) strategy is proposed to standardize the multimodal data, which can eliminate the multi-mode characteristics of the collected data, and normalize them into unimodal data distribution. After detailed analysis of the raised data preprocessing strategy, a new algorithm using WLS strategy with support vector data description(SVDD) is put forward to apply for multi-mode monitoring process. Unlike the strategy of building multiple local models, the developed method only contains a model without the prior knowledge of multi-mode process. To demonstrate the proposed method's validity, it is applied to a numerical example and a Tennessee Eastman(TE) process. Finally, the simulation results show that the WLS strategy is very effective to standardize multimodal data, and the WLS-SVDD monitoring method has great advantages over the traditional SVDD and PCA combined with a local standardization strategy(LNS-PCA) in multi-mode process monitoring.展开更多
Albumin has been widely applied for rational design of drug delivery complexes as natural carriers in cancer therapy due to its distinct advantages of biocompatibility,abundance,low toxicity and versatile property.Hen...Albumin has been widely applied for rational design of drug delivery complexes as natural carriers in cancer therapy due to its distinct advantages of biocompatibility,abundance,low toxicity and versatile property.Hence,various types of multifunctional albumin-based nanoplatforms(MAlb-NPs)that adopt multiple imaging and therapeutic techniques have been developed for cancer diagnosis and treatment.Stimuli-responsive release,including reduction-sensitive,p H-responsive,concentration-dependent and photodynamic-triggered,is important to achieve low-toxicity cancer therapy.Several types of imaging techniques can synergistically improve the effectiveness of cancer therapy.Therefore,combinational theranostic is considered to be a prospective strategy to improve treatment efficiency,minimize side effects and reduce drug resistance,which has received tremendous attentions in recent years.In this review,we highlight several stimuli-responsive albumin nanoplatforms for combinational theranostic.展开更多
The variability of the air-sea system in the low-frequency time domain can be decomposed into several systematic climate modes, namely, the decadal variability (DV) mode, the El Nino Southem Oscillation (ENSO) mod...The variability of the air-sea system in the low-frequency time domain can be decomposed into several systematic climate modes, namely, the decadal variability (DV) mode, the El Nino Southem Oscillation (ENSO) mode, the annual cycle (AC) mode, the semiannual cycle ( SC ) mode and the intraseasonal variability ( ISV ) mode. The combination of these primary modes in the air - sea system orchestrates a complex climate system. The multi-mode low-frequency variability in SST is investigated based on 22 a SST records from 1982 through 2003. The variation of SST in the past two decades undergoes a different combination of these dominant climate modes over different regions, which leads to an interesting new classification of the global ocean based on the relative importance of these modes. The new classification can provide ideal locations for better monitoring of these low-frequency modes in the scientific proof sense. Moreover, two no-annual variation and 14 no-semiannual variation oceanic points, termed annual and semiannual amphidromes, have been well defined in the AC and SC phase maps. The formation of these nodal points is attributed to the couplings of climate modes in EOF analysis results.展开更多
This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, using MATLAB. The tendon is...This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation(lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.展开更多
A memetic algorithm (MA) for a multi-mode resourceconstrained project scheduling problem (MRCPSP) is proposed. We use a new fitness function and two very effective local search procedures in the proposed MA. The f...A memetic algorithm (MA) for a multi-mode resourceconstrained project scheduling problem (MRCPSP) is proposed. We use a new fitness function and two very effective local search procedures in the proposed MA. The fitness function makes use of a mechanism called "strategic oscillation" to make the search process have a higher probability to visit solutions around a "feasible boundary". One of the local search procedures aims at improving the lower bound of project makespan to be less than a known upper bound, and another aims at improving a solution of an MRCPSP instance accepting infeasible solutions based on the new fitness function in the search process. A detailed computational experiment is set up using instances from the problem instance library PSPLIB. Computational results show that the proposed MA is very competitive with the state-of-the-art algorithms. The MA obtains improved solutions for one instance of set J30.展开更多
Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and ...Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and timely. First, FCM clustering is employed to classify the data into different clusters, which helps to estimate whether there is a fault and how many fault types there are. If fault signals exist, the fault vibration signals are then demodulated and decomposed into different frequency bands by MMEMD in order to be analyzed further. In order to overcome the mode mixing defect of empirical mode decomposition (EMD), a novel method called MMEMD is proposed. It is an improvement to masking empirical mode decomposition (MEMD). By adding multi-masking signals to the signals to be decomposed in different levels, it can restrain low-frequency components from mixing in highfrequency components effectively in the sifting process and then suppress the mode mixing. It has the advantages of easy implementation and strong ability of suppressing modal mixing. The fault type is determined by Hilbert envelope finally. The results of simulation signal decomposition showed the high performance of MMEMD. Experiments of bearing fault diagnosis in wind turbine bearing fault diagnosis proved the validity and high accuracy of the new method.展开更多
The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration freq...The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration frequency and amplitude, and gas velocity on these characteristics were considered. The average size, average density, size deviation coefficient, and density deviation coefficient were used to identify lignite size and density. The separation efficiency was adopted to evaluate the segregation performance,and the segregation mechanisms were explored. The results show that ε(size,max) of heterogeneous multisize-component lignite with K_(size) = 65% reaches 80% at f= 20 Hz, A = 5 mm, and N =(1,3). ε_(density,max) Of heterogeneous multi-density-component lignite with K_(density)= 25% reaches 50% at f = 15 Hz, A = 5 mm,and N =(1,1.5). The density segregations of 1-3 and 3-6 mm multi-component mixtures are remarkable,ε_(density,max)= 42% and 31% at f= 14 and 16 Hz, and A = 3 and 5 mm, respectively. The size segregation of 1-6 mm multi-component mixture is prominent and ε_(size,max)= 55% at f= 15 Hz, A = 5 mm. The mediumsized mixture with a narrow size distribution at low frequency is favorable for density segregation,and a mixture with a wider size distribution at high frequency is most favorable for size segregation.Precise control of gas flow and vibration as well as optimal design of the fluidized bed can improve the performance of segregation in the vibrated gas-fluidized bed.展开更多
The efficiency and accuracy are two most concerned issues in the modeling and simulation of multi-body systems involving contact and impact. This paper proposed a formulation based on the component mode synthesis meth...The efficiency and accuracy are two most concerned issues in the modeling and simulation of multi-body systems involving contact and impact. This paper proposed a formulation based on the component mode synthesis method for planar contact problems of flexible multi-body systems. A flexible body is divided into two parts: a contact zone and an un-contact zone. For the un-contact zone, by using the fixed-interface substructure method as reference, a few low-order modal coordinates are used to replace the nodal coordinates of the nodes, and meanwhile, the nodal coordinates of the local impact region are kept unchanged, therefore the total degrees of freedom (DOFs) are greatly cut down and the computational cost of the simulation is significantly reduced. By using additional constraint method, the impact constraint equations and kinematic constraint equations are derived, and the Lagrange equations of the first kind of flexible multi-body system are obtained. The impact of an elastic beam with a fixed half disk is simulated to verify the efficiency and accuracy of this method.展开更多
We propose a scheme to implement an unconventional geometric logic gate separately in a two-mode cavity and a multi-mode cavity assisted by a strong classical driving field. The effect of the cavity decay is included ...We propose a scheme to implement an unconventional geometric logic gate separately in a two-mode cavity and a multi-mode cavity assisted by a strong classical driving field. The effect of the cavity decay is included in the investigation. The numerical calculation is carried out, and the result shows that our scheme is more tolerant to cavity decay than the previous one because the time consumed for finishing the logic gate is doubly reduced.展开更多
Planar Bragg reflector operating in the sub-terahertz wavelength installed at the upstream end of a sheet beam back- ward wave oscillator (BWO) is very promising to minimize the whole circuit structure and make it m...Planar Bragg reflector operating in the sub-terahertz wavelength installed at the upstream end of a sheet beam back- ward wave oscillator (BWO) is very promising to minimize the whole circuit structure and make it more compact. In this paper, a sub-terahertz wavelength (0.18-0.22 THz) tunable planar Bragg reflector is numerically analyzed by using multi-mode coupling theory (MCT). The operating mode TE10 and dominant coupling mode TE01 are mainly considered in this theory. Reflection and transmission performance of the reflector are demonstrated in detail and the results, in excellent agreement with the theoretical analysis and simulation, are also presented in this paper. Self- and cross-coupling coefficients between these two modes are presented as well. The reflector behaviors with different Bragg dimensions are discussed and analyzed in the 0.16-0.22 THz range. The analysis in this paper can be of benefit to the design and fabrication of the whole BWO circuit.展开更多
This paper investigates the consensus problem of second-order nonlinear multi-agent systems (MASs) via the sliding mode control (SMC) approach. The velocity of each agent is assumed to be unmeasurable. A second-order ...This paper investigates the consensus problem of second-order nonlinear multi-agent systems (MASs) via the sliding mode control (SMC) approach. The velocity of each agent is assumed to be unmeasurable. A second-order sliding mode observer is designed to estimate the velocity. Then a distributed discontinuous control law based on first-order SMC is presented to solve the consensus problem. Moreover, to overcome the chatting problem, two controllers based on the boundary layer method and the super-twisting algorithm respectively are presented. It is shown that the MASs will achieve consensus under some given conditions. Some examples are provided to demonstrate the effectiveness of the proposed control laws.展开更多
Aiming at the needs of different lighting applications, combined with the characteristics of LED dimming and color control, and using MSP430 digital control technology, a novel LED intelligent dimming and color contro...Aiming at the needs of different lighting applications, combined with the characteristics of LED dimming and color control, and using MSP430 digital control technology, a novel LED intelligent dimming and color control system was designed. The system integrated Bluetooth remote, human infrared sensor, voice/gesture control and other control modes, which could achieve LED multi-mode dimming and color intelligent control. System hardware and software were designed to develop a prototype to experimental verification. The designed method proposes new ideas and information for LED control.展开更多
This paper consolidates the activity of design and fabrication of 2.9 - 4.32 GHz, 4.3 - 6.42 GHz, and 6.4 - 8.4 GHz filter bank. Novel compact microstrip bandpass filters with stub-loaded multi-mode resonators are pro...This paper consolidates the activity of design and fabrication of 2.9 - 4.32 GHz, 4.3 - 6.42 GHz, and 6.4 - 8.4 GHz filter bank. Novel compact microstrip bandpass filters with stub-loaded multi-mode resonators are proposed. Simulated results indicate that all the filters exhibit insertion losses less than 1.5 dB with passband ripples of 1 dB and sharp attenuations of above 40 dB in their stopbands. The maximums of input and output VSWRs are 1.742 and 1.734, respectively. Due to fabrication error, the initial measured passbands show frequency shifts and insertion losses in upper passbands deteriorate seriously. After tuning of the filter bank, measured results imply that the input and output VSWRs are found lower than 2.135 and 2.187, and the insertion loss in 1 dB bandwidth is less than 2.52 dB. Filter bank has a sharp skirt and out-of-band rejection levels approaching to 40 dB in all desired stopbands except at the frequencies near 2f0.展开更多
Decreasing mode coupling coefficient(κ) is an effective approach to suppress the inter-core crosstalk. Therefore, we deploy a low index rod and rectangle trench in the middle of two neighboring cores to reduce κ so ...Decreasing mode coupling coefficient(κ) is an effective approach to suppress the inter-core crosstalk. Therefore, we deploy a low index rod and rectangle trench in the middle of two neighboring cores to reduce κ so that the overlap of electric field distribution can be suppressed. We also propose approximate analytical solution(AAS) for κ of two crosstalk suppression models, which are two cores with one low index rod deployed in the middle and two cores with one low index rectangle trench deployed in the middle. We then do some modification for the results obtained by AAS and the modified results are proved to agree well with that obtained by finite element method(FEM). Therefore, we can use the modified AAS to get inter-core crosstalk for abovementioned two models quickly.展开更多
In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are car...In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.展开更多
文摘To address the difficulties in fusing multi-mode sensor data for complex industrial machinery, an adaptive deep coupling convolutional auto-encoder (ADCCAE) fusion method was proposed. First, the multi-mode features extracted synchronously by the CCAE were stacked and fed to the multi-channel convolution layers for fusion. Then, the fused data was passed to all connection layers for compression and fed to the Softmax module for classification. Finally, the coupling loss function coefficients and the network parameters were optimized through an adaptive approach using the gray wolf optimization (GWO) algorithm. Experimental comparisons showed that the proposed ADCCAE fusion model was superior to existing models for multi-mode data fusion.
基金sponsored by Study on High-Precision Logging While Drilling Imaging Technology of Low-Permeability Reservoirs(No.2016ZX05021-002)
文摘A new multi-mode resistivity imaging sonde, with toroidal coils as source, can conduct three resistivity measurements: azimuthal resistivity, lateral resistivity, and bit resistivity measurements. Thus, the logging time and cost are greatly saved. The toroidal coils are simplified as an extended voltage dipole and the response equations are derived for a homogenous formation. Based on 3D FEM, the depth of investigation(DOI), vertical resolution, circumferential azimuthal capacity, borehole diameter, mud resistivity, thickness of target formation, and the resistivity of the surrounding formation and mud invasion are simulated. The results suggest that the three measurement modes of the new sonde are different in vertical resolutions and DOIs. The circumferential detection ability of the azimuth button depends on the contrast between the anomaly and formation resistivity and the open angle of the anomaly. Whether the borehole is truncated at the bit or not has a great influence on the simulation results. The borehole and mud invasion affect the apparent resistivity in all modes, but the effects of resistivity of surrounding formation and thickness of the target formation are only corrected for lateral resistivity measurement.
基金supported by the National Natural Science Foundation of China(61371172)the International S&T Cooperation Program of China(2015DFR10220)+1 种基金the Ocean Engineering Project of National Key Laboratory Foundation(1213)the Fundamental Research Funds for the Central Universities(HEUCF1608)
文摘For the multi-mode radar working in the modern electronicbattlefield, different working states of one single radar areprone to being classified as multiple emitters when adoptingtraditional classification methods to process intercepted signals,which has a negative effect on signal classification. A classificationmethod based on spatial data mining is presented to address theabove challenge. Inspired by the idea of spatial data mining, theclassification method applies nuclear field to depicting the distributioninformation of pulse samples in feature space, and digs out thehidden cluster information by analyzing distribution characteristics.In addition, a membership-degree criterion to quantify the correlationamong all classes is established, which ensures classificationaccuracy of signal samples. Numerical experiments show that thepresented method can effectively prevent different working statesof multi-mode emitter from being classified as several emitters,and achieve higher classification accuracy.
基金Project(61374140)supported by the National Natural Science Foundation of China
文摘There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because their presumptions are that sampled-data should obey the single Gaussian distribution or non-Gaussian distribution. In order to solve these problems, a novel weighted local standardization(WLS) strategy is proposed to standardize the multimodal data, which can eliminate the multi-mode characteristics of the collected data, and normalize them into unimodal data distribution. After detailed analysis of the raised data preprocessing strategy, a new algorithm using WLS strategy with support vector data description(SVDD) is put forward to apply for multi-mode monitoring process. Unlike the strategy of building multiple local models, the developed method only contains a model without the prior knowledge of multi-mode process. To demonstrate the proposed method's validity, it is applied to a numerical example and a Tennessee Eastman(TE) process. Finally, the simulation results show that the WLS strategy is very effective to standardize multimodal data, and the WLS-SVDD monitoring method has great advantages over the traditional SVDD and PCA combined with a local standardization strategy(LNS-PCA) in multi-mode process monitoring.
文摘Albumin has been widely applied for rational design of drug delivery complexes as natural carriers in cancer therapy due to its distinct advantages of biocompatibility,abundance,low toxicity and versatile property.Hence,various types of multifunctional albumin-based nanoplatforms(MAlb-NPs)that adopt multiple imaging and therapeutic techniques have been developed for cancer diagnosis and treatment.Stimuli-responsive release,including reduction-sensitive,p H-responsive,concentration-dependent and photodynamic-triggered,is important to achieve low-toxicity cancer therapy.Several types of imaging techniques can synergistically improve the effectiveness of cancer therapy.Therefore,combinational theranostic is considered to be a prospective strategy to improve treatment efficiency,minimize side effects and reduce drug resistance,which has received tremendous attentions in recent years.In this review,we highlight several stimuli-responsive albumin nanoplatforms for combinational theranostic.
基金This research was jointly supported by the National Basic Research Program of China under contract N0.2005CB422308the National Natural Science Foundation of China under Contract N0.40545018the National Key laboratory of Remote Sensing Sciences.
文摘The variability of the air-sea system in the low-frequency time domain can be decomposed into several systematic climate modes, namely, the decadal variability (DV) mode, the El Nino Southem Oscillation (ENSO) mode, the annual cycle (AC) mode, the semiannual cycle ( SC ) mode and the intraseasonal variability ( ISV ) mode. The combination of these primary modes in the air - sea system orchestrates a complex climate system. The multi-mode low-frequency variability in SST is investigated based on 22 a SST records from 1982 through 2003. The variation of SST in the past two decades undergoes a different combination of these dominant climate modes over different regions, which leads to an interesting new classification of the global ocean based on the relative importance of these modes. The new classification can provide ideal locations for better monitoring of these low-frequency modes in the scientific proof sense. Moreover, two no-annual variation and 14 no-semiannual variation oceanic points, termed annual and semiannual amphidromes, have been well defined in the AC and SC phase maps. The formation of these nodal points is attributed to the couplings of climate modes in EOF analysis results.
文摘This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation(lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.
基金supported by the National Natural Science Foundation of China(71171038)
文摘A memetic algorithm (MA) for a multi-mode resourceconstrained project scheduling problem (MRCPSP) is proposed. We use a new fitness function and two very effective local search procedures in the proposed MA. The fitness function makes use of a mechanism called "strategic oscillation" to make the search process have a higher probability to visit solutions around a "feasible boundary". One of the local search procedures aims at improving the lower bound of project makespan to be less than a known upper bound, and another aims at improving a solution of an MRCPSP instance accepting infeasible solutions based on the new fitness function in the search process. A detailed computational experiment is set up using instances from the problem instance library PSPLIB. Computational results show that the proposed MA is very competitive with the state-of-the-art algorithms. The MA obtains improved solutions for one instance of set J30.
基金Supported by National Key R&D Projects(Grant No.2018YFB0905500)National Natural Science Foundation of China(Grant No.51875498)+1 种基金Hebei Provincial Natural Science Foundation of China(Grant Nos.E2018203439,E2018203339,F2016203496)Key Scientific Research Projects Plan of Henan Higher Education Institutions(Grant No.19B460001)
文摘Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and timely. First, FCM clustering is employed to classify the data into different clusters, which helps to estimate whether there is a fault and how many fault types there are. If fault signals exist, the fault vibration signals are then demodulated and decomposed into different frequency bands by MMEMD in order to be analyzed further. In order to overcome the mode mixing defect of empirical mode decomposition (EMD), a novel method called MMEMD is proposed. It is an improvement to masking empirical mode decomposition (MEMD). By adding multi-masking signals to the signals to be decomposed in different levels, it can restrain low-frequency components from mixing in highfrequency components effectively in the sifting process and then suppress the mode mixing. It has the advantages of easy implementation and strong ability of suppressing modal mixing. The fault type is determined by Hilbert envelope finally. The results of simulation signal decomposition showed the high performance of MMEMD. Experiments of bearing fault diagnosis in wind turbine bearing fault diagnosis proved the validity and high accuracy of the new method.
基金the National Natural Science Foundation of China (Nos. 51774283, 51174203)the Major International (Regional) Joint Research Project of NSFC (No. 51620105001) for the financial supports
文摘The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration frequency and amplitude, and gas velocity on these characteristics were considered. The average size, average density, size deviation coefficient, and density deviation coefficient were used to identify lignite size and density. The separation efficiency was adopted to evaluate the segregation performance,and the segregation mechanisms were explored. The results show that ε(size,max) of heterogeneous multisize-component lignite with K_(size) = 65% reaches 80% at f= 20 Hz, A = 5 mm, and N =(1,3). ε_(density,max) Of heterogeneous multi-density-component lignite with K_(density)= 25% reaches 50% at f = 15 Hz, A = 5 mm,and N =(1,1.5). The density segregations of 1-3 and 3-6 mm multi-component mixtures are remarkable,ε_(density,max)= 42% and 31% at f= 14 and 16 Hz, and A = 3 and 5 mm, respectively. The size segregation of 1-6 mm multi-component mixture is prominent and ε_(size,max)= 55% at f= 15 Hz, A = 5 mm. The mediumsized mixture with a narrow size distribution at low frequency is favorable for density segregation,and a mixture with a wider size distribution at high frequency is most favorable for size segregation.Precise control of gas flow and vibration as well as optimal design of the fluidized bed can improve the performance of segregation in the vibrated gas-fluidized bed.
基金supported by the National Natural Science Foundation of China (11132007 and 11272203)
文摘The efficiency and accuracy are two most concerned issues in the modeling and simulation of multi-body systems involving contact and impact. This paper proposed a formulation based on the component mode synthesis method for planar contact problems of flexible multi-body systems. A flexible body is divided into two parts: a contact zone and an un-contact zone. For the un-contact zone, by using the fixed-interface substructure method as reference, a few low-order modal coordinates are used to replace the nodal coordinates of the nodes, and meanwhile, the nodal coordinates of the local impact region are kept unchanged, therefore the total degrees of freedom (DOFs) are greatly cut down and the computational cost of the simulation is significantly reduced. By using additional constraint method, the impact constraint equations and kinematic constraint equations are derived, and the Lagrange equations of the first kind of flexible multi-body system are obtained. The impact of an elastic beam with a fixed half disk is simulated to verify the efficiency and accuracy of this method.
基金Project supported by the National Natural Science Foundation of China(Grant No.50874041)the Funds of Hunan Educational Bureau,China(Grant No.09C314)
文摘We propose a scheme to implement an unconventional geometric logic gate separately in a two-mode cavity and a multi-mode cavity assisted by a strong classical driving field. The effect of the cavity decay is included in the investigation. The numerical calculation is carried out, and the result shows that our scheme is more tolerant to cavity decay than the previous one because the time consumed for finishing the logic gate is doubly reduced.
基金supported by the National Natural Science Foundation of China(Grant No.G0501040161101040)
文摘Planar Bragg reflector operating in the sub-terahertz wavelength installed at the upstream end of a sheet beam back- ward wave oscillator (BWO) is very promising to minimize the whole circuit structure and make it more compact. In this paper, a sub-terahertz wavelength (0.18-0.22 THz) tunable planar Bragg reflector is numerically analyzed by using multi-mode coupling theory (MCT). The operating mode TE10 and dominant coupling mode TE01 are mainly considered in this theory. Reflection and transmission performance of the reflector are demonstrated in detail and the results, in excellent agreement with the theoretical analysis and simulation, are also presented in this paper. Self- and cross-coupling coefficients between these two modes are presented as well. The reflector behaviors with different Bragg dimensions are discussed and analyzed in the 0.16-0.22 THz range. The analysis in this paper can be of benefit to the design and fabrication of the whole BWO circuit.
基金supported by the National Natural Science Foundation of China(6137510561403334)
文摘This paper investigates the consensus problem of second-order nonlinear multi-agent systems (MASs) via the sliding mode control (SMC) approach. The velocity of each agent is assumed to be unmeasurable. A second-order sliding mode observer is designed to estimate the velocity. Then a distributed discontinuous control law based on first-order SMC is presented to solve the consensus problem. Moreover, to overcome the chatting problem, two controllers based on the boundary layer method and the super-twisting algorithm respectively are presented. It is shown that the MASs will achieve consensus under some given conditions. Some examples are provided to demonstrate the effectiveness of the proposed control laws.
文摘Aiming at the needs of different lighting applications, combined with the characteristics of LED dimming and color control, and using MSP430 digital control technology, a novel LED intelligent dimming and color control system was designed. The system integrated Bluetooth remote, human infrared sensor, voice/gesture control and other control modes, which could achieve LED multi-mode dimming and color intelligent control. System hardware and software were designed to develop a prototype to experimental verification. The designed method proposes new ideas and information for LED control.
文摘This paper consolidates the activity of design and fabrication of 2.9 - 4.32 GHz, 4.3 - 6.42 GHz, and 6.4 - 8.4 GHz filter bank. Novel compact microstrip bandpass filters with stub-loaded multi-mode resonators are proposed. Simulated results indicate that all the filters exhibit insertion losses less than 1.5 dB with passband ripples of 1 dB and sharp attenuations of above 40 dB in their stopbands. The maximums of input and output VSWRs are 1.742 and 1.734, respectively. Due to fabrication error, the initial measured passbands show frequency shifts and insertion losses in upper passbands deteriorate seriously. After tuning of the filter bank, measured results imply that the input and output VSWRs are found lower than 2.135 and 2.187, and the insertion loss in 1 dB bandwidth is less than 2.52 dB. Filter bank has a sharp skirt and out-of-band rejection levels approaching to 40 dB in all desired stopbands except at the frequencies near 2f0.
基金supported by National B a-sic Research Program of China(Grant No.2012CB315905)National Natural Science Foundation of China(Grant No.61501027)+1 种基金China Postdoctoral Science Foundation(Grant No.2015M570934)Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-15-031A1)
文摘Decreasing mode coupling coefficient(κ) is an effective approach to suppress the inter-core crosstalk. Therefore, we deploy a low index rod and rectangle trench in the middle of two neighboring cores to reduce κ so that the overlap of electric field distribution can be suppressed. We also propose approximate analytical solution(AAS) for κ of two crosstalk suppression models, which are two cores with one low index rod deployed in the middle and two cores with one low index rectangle trench deployed in the middle. We then do some modification for the results obtained by AAS and the modified results are proved to agree well with that obtained by finite element method(FEM). Therefore, we can use the modified AAS to get inter-core crosstalk for abovementioned two models quickly.
基金supports from National High Technology 863 Program of China(No.2013AA013403,2015AA015501,2015AA015502,2015AA015504)National NSFC(No.61425022/61522501/61307086/61475024/61275158/61201151/61275074/61372109)+4 种基金Beijing Nova Program(No.Z141101001814048)Beijing Excellent Ph.D.Thesis Guidance Foundation(No.20121001302)the Universities Ph.D.Special Research Funds(No.20120005110003/20120005120007)Fund of State Key Laboratory of IPOC(BUPT)P.R.China
文摘In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.