In this paper, we develop a decentralized algorithm to coord inate a group of mobile robots to search for unknown and transient radio sources. In addition to limited mobility and ranges of communication and sensing, t...In this paper, we develop a decentralized algorithm to coord inate a group of mobile robots to search for unknown and transient radio sources. In addition to limited mobility and ranges of communication and sensing, the robot team has to deal with challenges from signal source anonymity, short transmission duration, and variable transmission power. We propose a two-step approach: First, we decentralize belief functions that robots use to track source locations using checkpoint-based synchronization, and second, we propose a decentralized planning strategy to coordinate robots to ensure the existence of checkpoints. We analyze memory usage, data amount in communication, and searching time for the proposed algorithm. We have implemented the proposed algorithm and compared it with two heuristics. The experimental results show that our algorithm successfully trades a modest amount of memory for the fastest searching time among the three methods.展开更多
An adaptive PBC strategy for SM with a time-varying load torque to track fluxand speed trajectories was proposed.The key point of this method was the identificationof terms,known as workless forces,which appeared in t...An adaptive PBC strategy for SM with a time-varying load torque to track fluxand speed trajectories was proposed.The key point of this method was the identificationof terms,known as workless forces,which appeared in the dynamic equations of SM buthad no effect on the energy balance equation of the closed loop.PBC,combined withadaptive control schemes,not only preserved the advantages of PBC such as nonexistenceof singularity,but also rejected the flux and speed tracking error caused by statorand rotor resistance variation.The rotor currents of SM were estimated via a state observer.This algorithm simplified the control structure and enhanced the robustness of thecontrol system.The feasibility and effectiveness were confirmed by experimental resultsbased on dSPACE.展开更多
This paper proposes new interference estimation for power control in broadband wireless data networks. The proposed approach gives the filtered interference power in real-time removing undesired effects such as the fl...This paper proposes new interference estimation for power control in broadband wireless data networks. The proposed approach gives the filtered interference power in real-time removing undesired effects such as the fluctuation of interference power and the measurement noise due to receiver noise. The well-known Finite Impulse Response （FIR） structure filter is adopted for both the interference and the noise covarianee estimation. The proposed mechanism provides both the filtered interference power and the filtered number of active co-channel interferers, which shows good inherent properties. And the filtered interference power is not affected by the constant number of active co-channel interferes. It is also shown that the filtered number of active co-channel interference is separated from the filtered interference power. From discussions about the choice of design parameters such as window length and eovariance ratio, they can make the estimation performance of the proposed FIR filtering based mechanism as good as possible. Via extensive computer simulations, the performance of the proposed mechanism is shown to be superior to the existing Kalman filtering based mechanism.展开更多
Power line inspection is an essential procedure in the power lines maintenance area, especially thinking about service availability and energy efficiency. Aerial inspection of electric power transmission lines is typi...Power line inspection is an essential procedure in the power lines maintenance area, especially thinking about service availability and energy efficiency. Aerial inspection of electric power transmission lines is typically performed using human-piloted helicopters, which is a procedure that is both expensive and prone to accidents taking risks to human beings＇ lives. The work presents a solution based on UAS （unmanned aircraft system） for inspecting power lines. In this context a R ＆ D project of an unmanned aircraft system to be used for performing complete aerial inspection of overhead power lines is being executed by ITA （Instituto Tecnol6gico de Aeron^utica） （Technological Institute of Aeronautics） in Brazil. Special attention is dedicated to the communication system conception in order to comply with Remotely Piloted Aircraft System definition in the context of long endurance operations of the system. It presents a solution based on LTA （lighter than air） platform in order to extend the communication range beyond line of sight.展开更多
In this paper, we present hands-on experience related to on-going implementation in aircraft of power supply for a wireless sensor network deployed for aerodynamic flight tests. This autonomous battery-free power supp...In this paper, we present hands-on experience related to on-going implementation in aircraft of power supply for a wireless sensor network deployed for aerodynamic flight tests. This autonomous battery-free power supply is capturing, managing and storing primary energy from the environment, using solar light and PV （photovoltaic） cells. For practical purposes, it is also equipped with an auxiliary power input. The specifications are detailed, the general architecture is presented and justified, and test results are discussed.展开更多
Since the year of 2009 when the first appli- cation of organohalide lead perovskite as the light har- vester in solar cells was reported, tremendous attention has been devoted to these new types of perovskite-based so...Since the year of 2009 when the first appli- cation of organohalide lead perovskite as the light har- vester in solar cells was reported, tremendous attention has been devoted to these new types of perovskite-based solid-state solar cells and remarkable power conversion efficiency of over 20 % has been achieved to date. In this review, we first introduce the properties of organic- inorganic halide perovskites and then focus on the notable achievements made on the perovskite layer to improve the power conversion efficiency of solid-state perovskite solar cells, which is featured by process engineering of the state-of-the-art lead methylammoni- um triiodide perovskite and material control of lead triiodide perovskites and other newly emerged per- ovskites. In the end, we wish to provide an outlook of the future development in solid-state perovskite solar cells. Provided that the instability and toxicity of solid- state perovskite solar cells can be solved, we will wit- ness a new era for cost-effective and efficient solar cells.展开更多
基金supported in part by the National Science Foundation (IIS1318638 and IIS1426752)the Shenzhen Science and Technology Project (ZDS Y20120617113312191)
文摘In this paper, we develop a decentralized algorithm to coord inate a group of mobile robots to search for unknown and transient radio sources. In addition to limited mobility and ranges of communication and sensing, the robot team has to deal with challenges from signal source anonymity, short transmission duration, and variable transmission power. We propose a two-step approach: First, we decentralize belief functions that robots use to track source locations using checkpoint-based synchronization, and second, we propose a decentralized planning strategy to coordinate robots to ensure the existence of checkpoints. We analyze memory usage, data amount in communication, and searching time for the proposed algorithm. We have implemented the proposed algorithm and compared it with two heuristics. The experimental results show that our algorithm successfully trades a modest amount of memory for the fastest searching time among the three methods.
基金Supported by the National Basic Research Program of China(973 Program)(2005CB221505)the Special Scientific Research Foundation for Doctoral Subject of Colleges and Universities in China(20050248058)
文摘An adaptive PBC strategy for SM with a time-varying load torque to track fluxand speed trajectories was proposed.The key point of this method was the identificationof terms,known as workless forces,which appeared in the dynamic equations of SM buthad no effect on the energy balance equation of the closed loop.PBC,combined withadaptive control schemes,not only preserved the advantages of PBC such as nonexistenceof singularity,but also rejected the flux and speed tracking error caused by statorand rotor resistance variation.The rotor currents of SM were estimated via a state observer.This algorithm simplified the control structure and enhanced the robustness of thecontrol system.The feasibility and effectiveness were confirmed by experimental resultsbased on dSPACE.
文摘This paper proposes new interference estimation for power control in broadband wireless data networks. The proposed approach gives the filtered interference power in real-time removing undesired effects such as the fluctuation of interference power and the measurement noise due to receiver noise. The well-known Finite Impulse Response （FIR） structure filter is adopted for both the interference and the noise covarianee estimation. The proposed mechanism provides both the filtered interference power and the filtered number of active co-channel interferers, which shows good inherent properties. And the filtered interference power is not affected by the constant number of active co-channel interferes. It is also shown that the filtered number of active co-channel interference is separated from the filtered interference power. From discussions about the choice of design parameters such as window length and eovariance ratio, they can make the estimation performance of the proposed FIR filtering based mechanism as good as possible. Via extensive computer simulations, the performance of the proposed mechanism is shown to be superior to the existing Kalman filtering based mechanism.
文摘Power line inspection is an essential procedure in the power lines maintenance area, especially thinking about service availability and energy efficiency. Aerial inspection of electric power transmission lines is typically performed using human-piloted helicopters, which is a procedure that is both expensive and prone to accidents taking risks to human beings＇ lives. The work presents a solution based on UAS （unmanned aircraft system） for inspecting power lines. In this context a R ＆ D project of an unmanned aircraft system to be used for performing complete aerial inspection of overhead power lines is being executed by ITA （Instituto Tecnol6gico de Aeron^utica） （Technological Institute of Aeronautics） in Brazil. Special attention is dedicated to the communication system conception in order to comply with Remotely Piloted Aircraft System definition in the context of long endurance operations of the system. It presents a solution based on LTA （lighter than air） platform in order to extend the communication range beyond line of sight.
文摘In this paper, we present hands-on experience related to on-going implementation in aircraft of power supply for a wireless sensor network deployed for aerodynamic flight tests. This autonomous battery-free power supply is capturing, managing and storing primary energy from the environment, using solar light and PV （photovoltaic） cells. For practical purposes, it is also equipped with an auxiliary power input. The specifications are detailed, the general architecture is presented and justified, and test results are discussed.
基金supported by the Australian Research Council (ARC) through Discovery Project programs
文摘Since the year of 2009 when the first appli- cation of organohalide lead perovskite as the light har- vester in solar cells was reported, tremendous attention has been devoted to these new types of perovskite-based solid-state solar cells and remarkable power conversion efficiency of over 20 % has been achieved to date. In this review, we first introduce the properties of organic- inorganic halide perovskites and then focus on the notable achievements made on the perovskite layer to improve the power conversion efficiency of solid-state perovskite solar cells, which is featured by process engineering of the state-of-the-art lead methylammoni- um triiodide perovskite and material control of lead triiodide perovskites and other newly emerged per- ovskites. In the end, we wish to provide an outlook of the future development in solid-state perovskite solar cells. Provided that the instability and toxicity of solid- state perovskite solar cells can be solved, we will wit- ness a new era for cost-effective and efficient solar cells.
