The Experts below are selected from a list of 15324 Experts worldwide ranked by ideXlab platform

Fumio Okuyama - One of the best experts on this subject based on the ideXlab platform.

  • Study of the inverted-magnetron cold emission microelectronic vacuum gauge
    Ultramicroscopy, 1998
    Co-Authors: Dan Nicolaescu, Valeriu Filip, Fumio Okuyama
    Abstract:

    A microelectronic ionization vacuum gauge which is inverted-magnetron like is proposed and its operation is analysed theoretically. The device is based on the controlled motion of field emission (FE) electrons subject to crossed electric E and magnetic B fields. The electrons are shown to move on a cycloid-like Closed Trajectory. The sensitivity of the vacuum gauge is computed taking into account different cross sections for the ionization process. The time spent by the electron inside the device, which depends on its motion on the Z-axis, is computed assuming a uniform repelling electric field in this direction. An analysis is performed in order to find the conditions (geometrical and operational) necessary to maximize the vacuum gauge sensitivity. It is shown that loops in the electron trajectories and device dimensions should be large enough to allow the electrons to acquire enough kinetic energy for efficient ionization.

  • a conceptual design for a microelectronic ionization vacuum gauge
    Applied Surface Science, 1998
    Co-Authors: Dan Nicolaescu, Valeriu Filip, Fumio Okuyama
    Abstract:

    Abstract A novel cold emission microelectronics vacuum gauge is proposed and its operation is analysed theoretically. The device is based on the controlled motion of field emission (FE) electrons in a vacuum working space subject to crossed electric E and magnetic B fields. The arrangement is cylindrically symmetrical around the B axis while the radial electric field is applied between two coaxial surfaces. The electrons obtained from a circular FE cathode array placed between these surfaces are shown to move on a cycloid-like Closed Trajectory. Some electrons with enough kinetic energy ionize the residual gas molecules. The ions are collected by an external electrode. The sensitivity of the vacuum gauge is computed taking into account different cross sections for the ionization process of nitrogen molecules as function of electron kinetic energy and integrating over the electron path. The electron `time of flight' inside the device is computed assuming an uniform (repelling) electric field in the Z direction. An analysis is performed in order to find the conditions (geometrical and operational) necessary to improve the vacuum gauge sensitivity. It is shown that the device should be operated to allow large electron loops, but at the same time the device dimensions should be large enough to allow the electron to acquire enough kinetic energy for an efficient ionization process to take place.

Ye Langlang - One of the best experts on this subject based on the ideXlab platform.

  • A Crowdsourcing based Indoor Topology Construction Algorithm using the Forward and Backward Track Fusion of User Closed Trajectory
    2018 Ubiquitous Positioning Indoor Navigation and Location-Based Services (UPINLBS), 2018
    Co-Authors: Jiang Mengling, Luo Haiyong, Zhao Fang, Ye Langlang
    Abstract:

    At present, indoor location-based service has become a hot topic. The traditional approaches that rely on professional equipment and expertise to collect indoor maps has limited the rapid development of indoor location-based services. Adopting low-cost crowdsourcing methods to construct and maintain indoor maps with various sensors integrated in smart phones by common users is a development trend of constructing indoor map. The existing crowdsourcing-based indoor topology construction methods mostly use the pedometer based PDR (Pedestrian Dead Reckoning) to infer user trajectories, which suffers from the problem of accumulated estimation errors. To reduce the error of pedestrian dead reckoning and improve the accuracy of the indoor topology construction, we propose a novel indoor topology construction algorithm based on the user Closed Trajectory fusion. The algorithm requires the user to start and end a Trajectory loop at the same location when collecting data. Based on this Trajectory loop, we can perform the forward and backward dead reckoning starting from the starting and the ending point of the path, respectively. For instance, after completing the forward path inference, we can swap the starting point with the ending point, and then perform the reverse path inference. Last, we aggregate the coordinates obtained from the forward and reverse path inferences with the different weight. The weight is defined to be proportional to the confidence of the PDR, i.e., inversely proportional to the walking time from the starting location of path inference. Compared to the traditional unidirectional Trajectory inference method, our proposed algorithm can greatly reduce the accumulated error of dead reckoning by aggregating the bidirectional Trajectory inference. To improve the accuracy of heading estimation of each step, we Ieverage a radial Gaussian function to filter the compass noise, and adopt the multi-strategy fusion mechanism based on the difference of direction estimation using the gyroscope and compass. The paper further introduces the external contour of the building to calibrate the direction of the indoor topological path, and improves the accuracy of the indoor topological path construction. The experimental results shows that our proposed crowdsourcing-based indoor topology construction algorithm using the bidirectional Trajectory fusion scheme outperforms the traditional indoor topology construction algorithm that uses only the forward PDR and can obtain an average map accuracy of 0.40-meter.

  • UPINLBS - A Crowdsourcing based Indoor Topology Construction Algorithm using the Forward and Backward Track Fusion of User Closed Trajectory
    2018 Ubiquitous Positioning Indoor Navigation and Location-Based Services (UPINLBS), 2018
    Co-Authors: Jiang Mengling, Luo Haiyong, Zhao Fang, Ye Langlang
    Abstract:

    At present, indoor location-based service has become a hot topic. The traditional approaches that rely on professional equipment and expertise to collect indoor maps has limited the rapid development of indoor location-based services. Adopting low-cost crowdsourcing methods to construct and maintain indoor maps with various sensors integrated in smart phones by common users is a development trend of constructing indoor map. The existing crowdsourcing-based indoor topology construction methods mostly use the pedometer based PDR (Pedestrian Dead Reckoning) to infer user trajectories, which suffers from the problem of accumulated estimation errors. To reduce the error of pedestrian dead reckoning and improve the accuracy of the indoor topology construction, we propose a novel indoor topology construction algorithm based on the user Closed Trajectory fusion. The algorithm requires the user to start and end a Trajectory loop at the same location when collecting data. Based on this Trajectory loop, we can perform the forward and backward dead reckoning starting from the starting and the ending point of the path, respectively. For instance, after completing the forward path inference, we can swap the starting point with the ending point, and then perform the reverse path inference. Last, we aggregate the coordinates obtained from the forward and reverse path inferences with the different weight. The weight is defined to be proportional to the confidence of the PDR, i.e., inversely proportional to the walking time from the starting location of path inference. Compared to the traditional unidirectional Trajectory inference method, our proposed algorithm can greatly reduce the accumulated error of dead reckoning by aggregating the bidirectional Trajectory inference. To improve the accuracy of heading estimation of each step, we Ieverage a radial Gaussian function to filter the compass noise, and adopt the multi-strategy fusion mechanism based on the difference of direction estimation using the gyroscope and compass. The paper further introduces the external contour of the building to calibrate the direction of the indoor topological path, and improves the accuracy of the indoor topological path construction. The experimental results shows that our proposed crowdsourcing-based indoor topology construction algorithm using the bidirectional Trajectory fusion scheme outperforms the traditional indoor topology construction algorithm that uses only the forward PDR and can obtain an average map accuracy of 0.40-meter.

Zongli Lin - One of the best experts on this subject based on the ideXlab platform.

  • A complete stability analysis of planar linear systems under saturation
    IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, 2000
    Co-Authors: Zongli Lin
    Abstract:

    A complete stability analysis is performed on a planar system of the form x/spl dot/=/spl sigma/(Ax) where A is a Hurwitz matrix and /spl sigma/ is the saturation function. Necessary and sufficient conditions for the system to be globally asymptotically stable (GAS) or to have a Closed Trajectory are explicitly given in terms of the entries of A. These conditions also indicate that the system always has a Closed Trajectory if it is not GAS.

  • A complete stability analysis of planar linear systems under saturation
    Proceedings of the 38th IEEE Conference on Decision and Control (Cat. No.99CH36304), 1
    Co-Authors: Zongli Lin
    Abstract:

    A complete stability analysis is performed on a planar system of the form x/spl dot/=/spl sigma/(Ax), where A is a Hurwitz matrix and /spl sigma/ is the saturation function. Necessary and sufficient conditions for the system to be globally asymptotically stable or to have a Closed Trajectory are explicitly given in terms of the entries of A. These conditions also indicate that the system always has a Closed Trajectory if it is not globally asymptotically stable.

  • Null controllability and stabilization of linear systems subject to asymmetric actuator saturation
    Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187), 1
    Co-Authors: A.n. Pitsillides, Zongli Lin
    Abstract:

    This paper generalizes our recent results on the null controllable regions and the stabilizability of exponentially unstable linear systems subject to symmetric actuator saturation. The description of the null controllable region carries smoothly from the symmetric case to the asymmetric case. As to stabilization, we have to take a quite different approach since the earlier development relies mainly on the symmetric property of the vector field. Specifically, in this paper, we construct a Lyapunov function from a Closed Trajectory to show that this Closed Trajectory forms the boundary of the domain of attraction for a planar anti-stable system under the control of a saturated linear feedback. If the linear feedback is designed by the LQR method, then there is a unique limit cycle which forms the boundary of the domain of attraction. We further show that if the gain is increased along the direction of the LQR feedback, then the domain of attraction can be made arbitrarily close to the null controllable region. This design can be utilized to construct state feedback laws for higher order systems with two exponentially unstable poles.

Dan Nicolaescu - One of the best experts on this subject based on the ideXlab platform.

  • Study of the inverted-magnetron cold emission microelectronic vacuum gauge
    Ultramicroscopy, 1998
    Co-Authors: Dan Nicolaescu, Valeriu Filip, Fumio Okuyama
    Abstract:

    A microelectronic ionization vacuum gauge which is inverted-magnetron like is proposed and its operation is analysed theoretically. The device is based on the controlled motion of field emission (FE) electrons subject to crossed electric E and magnetic B fields. The electrons are shown to move on a cycloid-like Closed Trajectory. The sensitivity of the vacuum gauge is computed taking into account different cross sections for the ionization process. The time spent by the electron inside the device, which depends on its motion on the Z-axis, is computed assuming a uniform repelling electric field in this direction. An analysis is performed in order to find the conditions (geometrical and operational) necessary to maximize the vacuum gauge sensitivity. It is shown that loops in the electron trajectories and device dimensions should be large enough to allow the electrons to acquire enough kinetic energy for efficient ionization.

  • a conceptual design for a microelectronic ionization vacuum gauge
    Applied Surface Science, 1998
    Co-Authors: Dan Nicolaescu, Valeriu Filip, Fumio Okuyama
    Abstract:

    Abstract A novel cold emission microelectronics vacuum gauge is proposed and its operation is analysed theoretically. The device is based on the controlled motion of field emission (FE) electrons in a vacuum working space subject to crossed electric E and magnetic B fields. The arrangement is cylindrically symmetrical around the B axis while the radial electric field is applied between two coaxial surfaces. The electrons obtained from a circular FE cathode array placed between these surfaces are shown to move on a cycloid-like Closed Trajectory. Some electrons with enough kinetic energy ionize the residual gas molecules. The ions are collected by an external electrode. The sensitivity of the vacuum gauge is computed taking into account different cross sections for the ionization process of nitrogen molecules as function of electron kinetic energy and integrating over the electron path. The electron `time of flight' inside the device is computed assuming an uniform (repelling) electric field in the Z direction. An analysis is performed in order to find the conditions (geometrical and operational) necessary to improve the vacuum gauge sensitivity. It is shown that the device should be operated to allow large electron loops, but at the same time the device dimensions should be large enough to allow the electron to acquire enough kinetic energy for an efficient ionization process to take place.

Jiang Mengling - One of the best experts on this subject based on the ideXlab platform.

  • A Crowdsourcing based Indoor Topology Construction Algorithm using the Forward and Backward Track Fusion of User Closed Trajectory
    2018 Ubiquitous Positioning Indoor Navigation and Location-Based Services (UPINLBS), 2018
    Co-Authors: Jiang Mengling, Luo Haiyong, Zhao Fang, Ye Langlang
    Abstract:

    At present, indoor location-based service has become a hot topic. The traditional approaches that rely on professional equipment and expertise to collect indoor maps has limited the rapid development of indoor location-based services. Adopting low-cost crowdsourcing methods to construct and maintain indoor maps with various sensors integrated in smart phones by common users is a development trend of constructing indoor map. The existing crowdsourcing-based indoor topology construction methods mostly use the pedometer based PDR (Pedestrian Dead Reckoning) to infer user trajectories, which suffers from the problem of accumulated estimation errors. To reduce the error of pedestrian dead reckoning and improve the accuracy of the indoor topology construction, we propose a novel indoor topology construction algorithm based on the user Closed Trajectory fusion. The algorithm requires the user to start and end a Trajectory loop at the same location when collecting data. Based on this Trajectory loop, we can perform the forward and backward dead reckoning starting from the starting and the ending point of the path, respectively. For instance, after completing the forward path inference, we can swap the starting point with the ending point, and then perform the reverse path inference. Last, we aggregate the coordinates obtained from the forward and reverse path inferences with the different weight. The weight is defined to be proportional to the confidence of the PDR, i.e., inversely proportional to the walking time from the starting location of path inference. Compared to the traditional unidirectional Trajectory inference method, our proposed algorithm can greatly reduce the accumulated error of dead reckoning by aggregating the bidirectional Trajectory inference. To improve the accuracy of heading estimation of each step, we Ieverage a radial Gaussian function to filter the compass noise, and adopt the multi-strategy fusion mechanism based on the difference of direction estimation using the gyroscope and compass. The paper further introduces the external contour of the building to calibrate the direction of the indoor topological path, and improves the accuracy of the indoor topological path construction. The experimental results shows that our proposed crowdsourcing-based indoor topology construction algorithm using the bidirectional Trajectory fusion scheme outperforms the traditional indoor topology construction algorithm that uses only the forward PDR and can obtain an average map accuracy of 0.40-meter.

  • UPINLBS - A Crowdsourcing based Indoor Topology Construction Algorithm using the Forward and Backward Track Fusion of User Closed Trajectory
    2018 Ubiquitous Positioning Indoor Navigation and Location-Based Services (UPINLBS), 2018
    Co-Authors: Jiang Mengling, Luo Haiyong, Zhao Fang, Ye Langlang
    Abstract:

    At present, indoor location-based service has become a hot topic. The traditional approaches that rely on professional equipment and expertise to collect indoor maps has limited the rapid development of indoor location-based services. Adopting low-cost crowdsourcing methods to construct and maintain indoor maps with various sensors integrated in smart phones by common users is a development trend of constructing indoor map. The existing crowdsourcing-based indoor topology construction methods mostly use the pedometer based PDR (Pedestrian Dead Reckoning) to infer user trajectories, which suffers from the problem of accumulated estimation errors. To reduce the error of pedestrian dead reckoning and improve the accuracy of the indoor topology construction, we propose a novel indoor topology construction algorithm based on the user Closed Trajectory fusion. The algorithm requires the user to start and end a Trajectory loop at the same location when collecting data. Based on this Trajectory loop, we can perform the forward and backward dead reckoning starting from the starting and the ending point of the path, respectively. For instance, after completing the forward path inference, we can swap the starting point with the ending point, and then perform the reverse path inference. Last, we aggregate the coordinates obtained from the forward and reverse path inferences with the different weight. The weight is defined to be proportional to the confidence of the PDR, i.e., inversely proportional to the walking time from the starting location of path inference. Compared to the traditional unidirectional Trajectory inference method, our proposed algorithm can greatly reduce the accumulated error of dead reckoning by aggregating the bidirectional Trajectory inference. To improve the accuracy of heading estimation of each step, we Ieverage a radial Gaussian function to filter the compass noise, and adopt the multi-strategy fusion mechanism based on the difference of direction estimation using the gyroscope and compass. The paper further introduces the external contour of the building to calibrate the direction of the indoor topological path, and improves the accuracy of the indoor topological path construction. The experimental results shows that our proposed crowdsourcing-based indoor topology construction algorithm using the bidirectional Trajectory fusion scheme outperforms the traditional indoor topology construction algorithm that uses only the forward PDR and can obtain an average map accuracy of 0.40-meter.