Based on the inertial navigation system, the influences of the excursion of the inertial navigation system and the measurement error of the wireless pressure altimeter on the rotation and scale of the real image are q...Based on the inertial navigation system, the influences of the excursion of the inertial navigation system and the measurement error of the wireless pressure altimeter on the rotation and scale of the real image are quantitatively analyzed in scene matching. The log-polar transform (LPT) is utilized and an anti-rotation and anti- scale image matching algorithm is proposed based on the image edge feature point extraction. In the algorithm, the center point is combined with its four-neighbor points, and the corresponding computing process is put forward. Simulation results show that in the image rotation and scale variation range resulted from the navigation system error and the measurement error of the wireless pressure altimeter, the proposed image matching algo- rithm can satisfy the accuracy demands of the scene aided navigation system and provide the location error-correcting information of the system.展开更多
To investigate the effects of long-term low dose hormone replacement therapy (HRT) on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy (MRS) parameters...To investigate the effects of long-term low dose hormone replacement therapy (HRT) on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy (MRS) parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [ estradiol (E2 ) 0. 5-1.0 mg and progesterone 0.5-2.0 mg, once a day ] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay (ELISA). The gene types of apolipoprotein E (ApoE) were measured by polymerase chain reaction, and the subjects with susceptible genes ( ApoE ε3/ε4) of Alzheimer's disease (AD) were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging (MRI), and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher (P 〈0. 05) except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 (HRT group 14 cases, control group 11 cases) showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group (0. 406 ± 0.028) was signiticantlyhigher than control gronp (0.369±0.031, P〈0.05). Theresults of ^1H MRS for the subjects with susceptible genes ApoE ε3/ε4 ( HRT group 12 cases, control group 11 cases) showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group ( 1.54±0. 08 ) were significantly higher than control group ( 1.45±0. 13, P 〈 0. 05). Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε3 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.展开更多
Objective: To investigate the activation (phosphorylation) and subcellular localization of extracellular signal-regulated kinase (ERK1/2), as well as the possible mechanism, following cerebral ischemia and ischem...Objective: To investigate the activation (phosphorylation) and subcellular localization of extracellular signal-regulated kinase (ERK1/2), as well as the possible mechanism, following cerebral ischemia and ischemia/reperfusion in rat hippocampus. Methods: Transient brain ischemia was induced by the four-vessel occlusion method in Sprague-Dawley rats. Western blot analysis. Results: During cerebral ischemia without reperfusion ERK1/2 activation immediately increased with a peak at 5 min and then decreased in the cytosol fraction, which was paralleled by the increase of ERK1/2 activation in the nucleus fraction. During reperfusion, ERK1/2 was activated with peaks occurring at 10 min in the cytosol and at 30 min in the nucleus, respectively. Under those conditions, the protein expressions had no significant change. In order to clarify the possible mechanism of ERK1/2 activation, the rats were intraperitoneally administrated with N-methyl-D-aspartate (NMDA) receptor antagonist dextromethorphan (DM), L-type voltage-gated Ca^2+ channel (L-VGCC) antagonist nifedipine (ND) 20 rain before ischemia, finding that DM and ND markedly prevented ERK1/2 activation of nucleus fraction induced by reperfusion, not by ischemia. Conclusion: These results suggested that the nuclear translocation mainly occurred during ischemia, while ischemia-reperfusion induced ERK1/2 activation both in the cytosol and the nucleus. Two type calcium channels contributed, at least partially, to the activation of ERK1/2.展开更多
The mechanical-touched detector was used commonly in textile production limes. It has some defect with high false alarm rate, response delay and high maintenance cost. In order to overcome such defects, a new kind dev...The mechanical-touched detector was used commonly in textile production limes. It has some defect with high false alarm rate, response delay and high maintenance cost. In order to overcome such defects, a new kind device was developed and used to detect roller tangled in the production lines. It is based on image processing. The core algorithm was composed of Canny edge detection, removing interference, detection of perpendicularity line and detection of broken tow. After the four steps, the broken tow could be recognized quickly and correctly. The algorithm is robust and high efficiency. So, the detection device has characteristic of stable, quickly-response and low maintains cost. It can keep superiority with long lifespan even in more formidable conditions. It guarantees a safe and stable production condition.展开更多
The problems of installation and integration of complex suite of software for processing medical images. Based analysis of the situation is realized in an easier integration of an automated system using the latest inf...The problems of installation and integration of complex suite of software for processing medical images. Based analysis of the situation is realized in an easier integration of an automated system using the latest information technologies using the web - environment for analysis and segmentation of DICOM - images.展开更多
To further improve delay performance in multi-cell cellular edge computing systems,a new delay-driven joint communication and computing resource BP(backpressure)scheduling algorithm is proposed.Firstly,the mathematica...To further improve delay performance in multi-cell cellular edge computing systems,a new delay-driven joint communication and computing resource BP(backpressure)scheduling algorithm is proposed.Firstly,the mathematical models of the communication delay and computing delay in multi-cell cellular edge computing systems are established and expressed as virtual delay queues.Then,based on the virtual delay models,a novel joint wireless subcarrier and virtual machine resource scheduling algorithm is proposed to stabilize the virtual delay queues in the framework of the BP scheduling principle.Finally,the delay performance of the proposed virtual queue-based BP scheduling algorithm is evaluated via simulation experiments and compared with the traditional queue length-based BP scheduling algorithm.Results show that under the considered simulation parameters,the total delay of the proposed BP scheduling algorithm is always lower than that of the traditional queue length-based BP scheduling algorithm.The percentage of the reduced total delay can be as high as 51.29%when the computing resources are heterogeneously configured.Therefore,compared with the traditional queue length-based BP scheduling algorithms,the proposed virtual delay queue-based BP scheduling algorithm can further reduce delay in multi-cell cellular edge computing systems.展开更多
The benefits of integrating locally adaptable water and nutrient management technologies were explored in semi-arid Zimbabwe. On-farm maize based experiments were set up on six farmers' fields in Ward 5, Shurugwi. Th...The benefits of integrating locally adaptable water and nutrient management technologies were explored in semi-arid Zimbabwe. On-farm maize based experiments were set up on six farmers' fields in Ward 5, Shurugwi. Three tillage systems namely Post-Emergence Tied Ridging (PETR), Rip & Pot-Holing (RPH) and Conventional Mouldboard Ploughing (CMP) were integrated to three nutrient management regimes, i.e. a control with no fertility amelioration, pit-stored cattle manure band applied at 10 t/ha and the latter with an additional top dressing of ammonium nitrate (34.5% N) at 100 kg/ha. On each site the treatments were set up as a completely randomized split-plot block design replicated 3 times with tillage (water management) as the main treatment and fertility as the sub-treatment. CMP mimicked the farmers' common land preparation practice while PETR and RPH systems represented the improved water harvesting tillage techniques. Results revealed significant nutrient management effects right from the first season giving 3-year means of 1,298, 1,977 and 2,490 kg/ha for the control, manure and manure plus fertilizer treatments respectively. On the other hand, water harvesting tillage effects were insignificant initially (2003/4) but had beneficial effects in subsequent seasons (2004/5 and 2005/6) with 3-year grain yield means of 1,624, 2,032 and 2,108 kg/ha for CMP, PETR and RPH, respectively. Maximum yield benefits from integrating PETR and RPH with manure + AN fertility ameliorants amounted to 218 and 261% respectively, compared to CMP with no fertility amendment. The results therefore showed increased benefits when in-situ water harvesting tillage techniques are integrated with appropriate nutrient ameliorants giving realizable food security benefits to the farmer.展开更多
To further reduce the delay in cellular edge computing systems, a new type of resource scheduling algorithm is proposed. Without assuming the knowledge of the statistics of user task arrival traffic, the analytical fo...To further reduce the delay in cellular edge computing systems, a new type of resource scheduling algorithm is proposed. Without assuming the knowledge of the statistics of user task arrival traffic, the analytical formulae of the communication and computing queueing delays in many-to-one multi-server cellular edge computing systems are derived by using the arriving curve and leaving curve. Based on the analytical formulae, an optimization problem of delay minimization is directly formulated, and then a novel scheduling algorithm is designed. The delay performance of the proposed algorithm is evaluated via simulation experiments. Under the considered simulation parameters, the proposed algorithm can achieve 12% less total delay, as compared to the traditional algorithms. System parameters including the weight, the amount of computing resources provided by servers, and the average user task arrival rate have impact on the percentage of delay reduction. Therefore, compared with the queue length optimization based traditional scheduling algorithms, the proposed delay optimization-based scheduling algorithm can further reduce delay.展开更多
With the increasing necessities for reliable printed circuit board(PCB) product, there has been a considerable demand for high speed and high precision vision positioning system. To locate a rectangular lead component...With the increasing necessities for reliable printed circuit board(PCB) product, there has been a considerable demand for high speed and high precision vision positioning system. To locate a rectangular lead component with high accuracy and reliability, a new visual positioning method was introduced. Considering the limitations of Ghosal sub-pixel edge detection algorithm, an improved algorithm was proposed, in which Harris corner features were used to coarsely detect the edge points and Zernike moments were adopted to accurately detect the edge points. Besides, two formulas were developed to determine the edge intersections whose sub-pixel coordinates were calculated with bilinear interpolation and conjugate gradient method. The last experimental results show that the proposed method can detect the deflection and offset, and the detection errors are less than 0.04° and 0.02 pixels.展开更多
Fast reciprocating probe systems ( FRPS ) are widely used in some tokamaks, such as JT- 60 U, TEXT and DIlI-D. The parameters with high temporal-spatial resolution are measured for boundary plasmas using these syste...Fast reciprocating probe systems ( FRPS ) are widely used in some tokamaks, such as JT- 60 U, TEXT and DIlI-D. The parameters with high temporal-spatial resolution are measured for boundary plasmas using these systems. The FRPS on HL-2A is developed, which is composed of transmission bar, digital grating displacement system, electromagnetic valves, stepping motor and so on. The high-pressure gas from the electromagnetic valves controlled by trigger signals provides the power to drive the transmission bar forward or backward. Reciprocating distance is 8 cm with the maximum speed of 1.5 m·s^-1.展开更多
A motion control system for a parallel robot with image positioning was implemented in this paper. The system is composed of a machine vision device, a delta robot and a linear stage, and the concerned hardware, softw...A motion control system for a parallel robot with image positioning was implemented in this paper. The system is composed of a machine vision device, a delta robot and a linear stage, and the concerned hardware, software and working methods were developed completely and verified successfully. During the phase of machine vision, the image of object was captured by camera, and then the process of smoothing filter, threshold algorithm and edge detection, was applied so as to obtain the edges of image. Finally, DV-GHT (Displacement Vector Generalized Hough Transformation) algorithm was used to recognize the center of multiple and arbitrary 2-D shapes objects. After the center of objects was recognized, the objects were delivered to the workspace of a delta robot by a motorized stage. Through the coordinate transformation between the camera and the robot system, the information of center can be converted to control commands for every working motors. Following, the delta robot picks up objects to the specified position sequentially by the trajectory planning and tracking controls. The software of C++/CLI is used to achieve the phase of motion controls and the program of DV-GHT is used to detect and conduct the positions for four different characteristics of the objects simultaneously so as to indicate the delta robot to classify the objects successfully.展开更多
A signal pre-processing method based on optimal variational mode decomposition(OVMD)is proposed to improve the efficiency and accuracy of local data filtering and analysis of edge nodes in distributed electromechanica...A signal pre-processing method based on optimal variational mode decomposition(OVMD)is proposed to improve the efficiency and accuracy of local data filtering and analysis of edge nodes in distributed electromechanical systems.Firstly,the singular points of original signals are eliminated effectively by using the first-order difference method.Then the OVMD method is applied for signal modal decomposition.Furthermore,correlation analysis is conducted to determine the degree of correlation between each mode and the original signal,so as to accurately separate the real operating signal from noise signal.On the basis of theoretical analysis and simulation,an edge node pre-processing system for distributed electromechanical system is designed.Finally,by virtue of the signal-to-noise ratio(SNR)and root-mean-square error(RMSE)indicators,the signal pre-processing effect is evaluated.The experimental results show that the OVMD-based edge node pre-processing system can extract signals with different characteristics and improve the SNR of reconstructed signals.Due to its high fidelity and reliability,this system can also provide data quality assurance for subsequent system health monitoring and fault diagnosis.展开更多
Numerous edge-chasing deadlock detection algonthms were developed lor the cycle detection in distributed systems, but their detections had the n steps speed limitation and n ( n- 1) overhead limitation to detect a c...Numerous edge-chasing deadlock detection algonthms were developed lor the cycle detection in distributed systems, but their detections had the n steps speed limitation and n ( n- 1) overhead limitation to detect a cycle of size n under the one-resource request model. Since fast deadlock detection is critical, this paper proposed a new algorithm to speed up the detection process. In our algorithm, when the running of a transaction node is blocked, the being requested resource nodes reply it with the waiting or being waited message simultaneously, so the blocked node knows both its predecessors and successors, which helps it detecting a cycle of size 2 directly and locally. For the cycle of size n ( n 〉 2), a special probe is produced which has the predecessors information of its originator, so the being detected nodes know their indirect predecessors and direct successors, and can detect the cycle within n - 2 steps. The proposed algorithm is formally proved to be correct by the invariant verification method. Performance evaluation shows that the message overhead of our detection is ( n^2 - n - 2)/2, hence both the detection speed and message cost of the proposed algorithm are better than that of the existing al gorithms.展开更多
文摘Based on the inertial navigation system, the influences of the excursion of the inertial navigation system and the measurement error of the wireless pressure altimeter on the rotation and scale of the real image are quantitatively analyzed in scene matching. The log-polar transform (LPT) is utilized and an anti-rotation and anti- scale image matching algorithm is proposed based on the image edge feature point extraction. In the algorithm, the center point is combined with its four-neighbor points, and the corresponding computing process is put forward. Simulation results show that in the image rotation and scale variation range resulted from the navigation system error and the measurement error of the wireless pressure altimeter, the proposed image matching algo- rithm can satisfy the accuracy demands of the scene aided navigation system and provide the location error-correcting information of the system.
文摘To investigate the effects of long-term low dose hormone replacement therapy (HRT) on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy (MRS) parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [ estradiol (E2 ) 0. 5-1.0 mg and progesterone 0.5-2.0 mg, once a day ] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay (ELISA). The gene types of apolipoprotein E (ApoE) were measured by polymerase chain reaction, and the subjects with susceptible genes ( ApoE ε3/ε4) of Alzheimer's disease (AD) were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging (MRI), and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher (P 〈0. 05) except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 (HRT group 14 cases, control group 11 cases) showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group (0. 406 ± 0.028) was signiticantlyhigher than control gronp (0.369±0.031, P〈0.05). Theresults of ^1H MRS for the subjects with susceptible genes ApoE ε3/ε4 ( HRT group 12 cases, control group 11 cases) showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group ( 1.54±0. 08 ) were significantly higher than control group ( 1.45±0. 13, P 〈 0. 05). Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε3 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.
基金Supported by grants from the Education Departmental Natural Science Research Funds of Hebei and Jiangsu Provinces of China (200510604KJD310207)the Key Project of the National Natural Science Foundation of China (No. 30330190).
文摘Objective: To investigate the activation (phosphorylation) and subcellular localization of extracellular signal-regulated kinase (ERK1/2), as well as the possible mechanism, following cerebral ischemia and ischemia/reperfusion in rat hippocampus. Methods: Transient brain ischemia was induced by the four-vessel occlusion method in Sprague-Dawley rats. Western blot analysis. Results: During cerebral ischemia without reperfusion ERK1/2 activation immediately increased with a peak at 5 min and then decreased in the cytosol fraction, which was paralleled by the increase of ERK1/2 activation in the nucleus fraction. During reperfusion, ERK1/2 was activated with peaks occurring at 10 min in the cytosol and at 30 min in the nucleus, respectively. Under those conditions, the protein expressions had no significant change. In order to clarify the possible mechanism of ERK1/2 activation, the rats were intraperitoneally administrated with N-methyl-D-aspartate (NMDA) receptor antagonist dextromethorphan (DM), L-type voltage-gated Ca^2+ channel (L-VGCC) antagonist nifedipine (ND) 20 rain before ischemia, finding that DM and ND markedly prevented ERK1/2 activation of nucleus fraction induced by reperfusion, not by ischemia. Conclusion: These results suggested that the nuclear translocation mainly occurred during ischemia, while ischemia-reperfusion induced ERK1/2 activation both in the cytosol and the nucleus. Two type calcium channels contributed, at least partially, to the activation of ERK1/2.
文摘The mechanical-touched detector was used commonly in textile production limes. It has some defect with high false alarm rate, response delay and high maintenance cost. In order to overcome such defects, a new kind device was developed and used to detect roller tangled in the production lines. It is based on image processing. The core algorithm was composed of Canny edge detection, removing interference, detection of perpendicularity line and detection of broken tow. After the four steps, the broken tow could be recognized quickly and correctly. The algorithm is robust and high efficiency. So, the detection device has characteristic of stable, quickly-response and low maintains cost. It can keep superiority with long lifespan even in more formidable conditions. It guarantees a safe and stable production condition.
文摘The problems of installation and integration of complex suite of software for processing medical images. Based analysis of the situation is realized in an easier integration of an automated system using the latest information technologies using the web - environment for analysis and segmentation of DICOM - images.
基金The National Natural Science Foundation of China(No.61571111)the Incubation Project of the National Natural Science Foundation of China at Nanjing University of Posts and Telecommunications(No.NY219106)
文摘To further improve delay performance in multi-cell cellular edge computing systems,a new delay-driven joint communication and computing resource BP(backpressure)scheduling algorithm is proposed.Firstly,the mathematical models of the communication delay and computing delay in multi-cell cellular edge computing systems are established and expressed as virtual delay queues.Then,based on the virtual delay models,a novel joint wireless subcarrier and virtual machine resource scheduling algorithm is proposed to stabilize the virtual delay queues in the framework of the BP scheduling principle.Finally,the delay performance of the proposed virtual queue-based BP scheduling algorithm is evaluated via simulation experiments and compared with the traditional queue length-based BP scheduling algorithm.Results show that under the considered simulation parameters,the total delay of the proposed BP scheduling algorithm is always lower than that of the traditional queue length-based BP scheduling algorithm.The percentage of the reduced total delay can be as high as 51.29%when the computing resources are heterogeneously configured.Therefore,compared with the traditional queue length-based BP scheduling algorithms,the proposed virtual delay queue-based BP scheduling algorithm can further reduce delay in multi-cell cellular edge computing systems.
文摘The benefits of integrating locally adaptable water and nutrient management technologies were explored in semi-arid Zimbabwe. On-farm maize based experiments were set up on six farmers' fields in Ward 5, Shurugwi. Three tillage systems namely Post-Emergence Tied Ridging (PETR), Rip & Pot-Holing (RPH) and Conventional Mouldboard Ploughing (CMP) were integrated to three nutrient management regimes, i.e. a control with no fertility amelioration, pit-stored cattle manure band applied at 10 t/ha and the latter with an additional top dressing of ammonium nitrate (34.5% N) at 100 kg/ha. On each site the treatments were set up as a completely randomized split-plot block design replicated 3 times with tillage (water management) as the main treatment and fertility as the sub-treatment. CMP mimicked the farmers' common land preparation practice while PETR and RPH systems represented the improved water harvesting tillage techniques. Results revealed significant nutrient management effects right from the first season giving 3-year means of 1,298, 1,977 and 2,490 kg/ha for the control, manure and manure plus fertilizer treatments respectively. On the other hand, water harvesting tillage effects were insignificant initially (2003/4) but had beneficial effects in subsequent seasons (2004/5 and 2005/6) with 3-year grain yield means of 1,624, 2,032 and 2,108 kg/ha for CMP, PETR and RPH, respectively. Maximum yield benefits from integrating PETR and RPH with manure + AN fertility ameliorants amounted to 218 and 261% respectively, compared to CMP with no fertility amendment. The results therefore showed increased benefits when in-situ water harvesting tillage techniques are integrated with appropriate nutrient ameliorants giving realizable food security benefits to the farmer.
基金The National Natural Science Foundation of China(No.61571111)
文摘To further reduce the delay in cellular edge computing systems, a new type of resource scheduling algorithm is proposed. Without assuming the knowledge of the statistics of user task arrival traffic, the analytical formulae of the communication and computing queueing delays in many-to-one multi-server cellular edge computing systems are derived by using the arriving curve and leaving curve. Based on the analytical formulae, an optimization problem of delay minimization is directly formulated, and then a novel scheduling algorithm is designed. The delay performance of the proposed algorithm is evaluated via simulation experiments. Under the considered simulation parameters, the proposed algorithm can achieve 12% less total delay, as compared to the traditional algorithms. System parameters including the weight, the amount of computing resources provided by servers, and the average user task arrival rate have impact on the percentage of delay reduction. Therefore, compared with the queue length optimization based traditional scheduling algorithms, the proposed delay optimization-based scheduling algorithm can further reduce delay.
基金Project(51175242)supported by the National Natural Science Foundation of ChinaProject(BA2012031)supported by the Jiangsu Province Science and Technology Foundation of China
文摘With the increasing necessities for reliable printed circuit board(PCB) product, there has been a considerable demand for high speed and high precision vision positioning system. To locate a rectangular lead component with high accuracy and reliability, a new visual positioning method was introduced. Considering the limitations of Ghosal sub-pixel edge detection algorithm, an improved algorithm was proposed, in which Harris corner features were used to coarsely detect the edge points and Zernike moments were adopted to accurately detect the edge points. Besides, two formulas were developed to determine the edge intersections whose sub-pixel coordinates were calculated with bilinear interpolation and conjugate gradient method. The last experimental results show that the proposed method can detect the deflection and offset, and the detection errors are less than 0.04° and 0.02 pixels.
文摘Fast reciprocating probe systems ( FRPS ) are widely used in some tokamaks, such as JT- 60 U, TEXT and DIlI-D. The parameters with high temporal-spatial resolution are measured for boundary plasmas using these systems. The FRPS on HL-2A is developed, which is composed of transmission bar, digital grating displacement system, electromagnetic valves, stepping motor and so on. The high-pressure gas from the electromagnetic valves controlled by trigger signals provides the power to drive the transmission bar forward or backward. Reciprocating distance is 8 cm with the maximum speed of 1.5 m·s^-1.
文摘A motion control system for a parallel robot with image positioning was implemented in this paper. The system is composed of a machine vision device, a delta robot and a linear stage, and the concerned hardware, software and working methods were developed completely and verified successfully. During the phase of machine vision, the image of object was captured by camera, and then the process of smoothing filter, threshold algorithm and edge detection, was applied so as to obtain the edges of image. Finally, DV-GHT (Displacement Vector Generalized Hough Transformation) algorithm was used to recognize the center of multiple and arbitrary 2-D shapes objects. After the center of objects was recognized, the objects were delivered to the workspace of a delta robot by a motorized stage. Through the coordinate transformation between the camera and the robot system, the information of center can be converted to control commands for every working motors. Following, the delta robot picks up objects to the specified position sequentially by the trajectory planning and tracking controls. The software of C++/CLI is used to achieve the phase of motion controls and the program of DV-GHT is used to detect and conduct the positions for four different characteristics of the objects simultaneously so as to indicate the delta robot to classify the objects successfully.
基金National Natural Science Foundation of China(No.61903291)Industrialization Project of Shaanxi Provincial Department of Education(No.18JC018)。
文摘A signal pre-processing method based on optimal variational mode decomposition(OVMD)is proposed to improve the efficiency and accuracy of local data filtering and analysis of edge nodes in distributed electromechanical systems.Firstly,the singular points of original signals are eliminated effectively by using the first-order difference method.Then the OVMD method is applied for signal modal decomposition.Furthermore,correlation analysis is conducted to determine the degree of correlation between each mode and the original signal,so as to accurately separate the real operating signal from noise signal.On the basis of theoretical analysis and simulation,an edge node pre-processing system for distributed electromechanical system is designed.Finally,by virtue of the signal-to-noise ratio(SNR)and root-mean-square error(RMSE)indicators,the signal pre-processing effect is evaluated.The experimental results show that the OVMD-based edge node pre-processing system can extract signals with different characteristics and improve the SNR of reconstructed signals.Due to its high fidelity and reliability,this system can also provide data quality assurance for subsequent system health monitoring and fault diagnosis.
文摘Numerous edge-chasing deadlock detection algonthms were developed lor the cycle detection in distributed systems, but their detections had the n steps speed limitation and n ( n- 1) overhead limitation to detect a cycle of size n under the one-resource request model. Since fast deadlock detection is critical, this paper proposed a new algorithm to speed up the detection process. In our algorithm, when the running of a transaction node is blocked, the being requested resource nodes reply it with the waiting or being waited message simultaneously, so the blocked node knows both its predecessors and successors, which helps it detecting a cycle of size 2 directly and locally. For the cycle of size n ( n 〉 2), a special probe is produced which has the predecessors information of its originator, so the being detected nodes know their indirect predecessors and direct successors, and can detect the cycle within n - 2 steps. The proposed algorithm is formally proved to be correct by the invariant verification method. Performance evaluation shows that the message overhead of our detection is ( n^2 - n - 2)/2, hence both the detection speed and message cost of the proposed algorithm are better than that of the existing al gorithms.