365 research outputs found

    Economic Growth and Water Pollution in the Circum-Bohai-Sea Zone in China - An Environmental Kuznets Curve Analysis

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    Based on the principle and model of Environmental Kuznets Curve (EKC), the present paper examines the relationship between water pollution and economic growth in the Circum-Bohai-Sea Zone of Beijing, Tianjin, Hebei Province, Shandong Province, and Liaoning Province with the annual time series data for 2003 to 2017. By analyzing the industrial, household, and total wastewater discharge separately as the measurement of water pollution, the results are consistent with the EKC model. In particular, according to econometric analysis, the variables of economic growth and per capita GDP are statistically significant in domestic and total wastewater discharge cases. However, the association of industrial wastewater discharge and economic development is more significant in the N-type EKC model, according to estimation results. This implies that water pollution will worsen without increased government interventions and management. The sub-goal is to investigate the impact of technologies on the EKC model in each subregion. By using the number of universities as a proxy of technology and observing the turning point, it can be assumed that technology can help decrease the level of water pollution, though trends in Shandong Province challenge this finding

    Resilient planning, task assignment and control for multi-robot systems against plan-deviation attacks

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    The security of multi-robot systems is critical in various applications such as patrol, transportation, and search and rescue operations, where they face threats from adversaries attempting to gain control of the robots. These compromised robots are significant threats as they allow attackers to steer robots towards forbidden areas without being detected, potentially causing harm or compromising the mission. To address this problem, we propose a resilient planning, task assignment, and control framework. The proposed framework builds a multi-robot plan where robots are designed to get close enough to other robots according to a co-observation schedule, in order to mutually check for abnormal behaviors. For the first part of the thesis, we propose an optimal trajectory solver based on the alternating direction method of multipliers (ADMM) to generate multi-agent trajectories that satisfy spatio-temporal requirements introduced by the co-observation schedules. As part of the formulation, we provide a new reachability constraint to guarantee that, despite adversarial movement by the attacker, a compromised robot cannot reach forbidden areas between co-observations without being detected. In the second part of the thesis, to further enhance the system's performance, reliability, and robustness, we propose to deploy multiple robots on each route to form sub-teams. A new cross-trajectory co-observation scheme between sub-teams is introduced that preserves the optimal unsecured trajectories. The new planner ensures that at least one robot in each sub-team sticks to the planned trajectories, while sub-teams can constantly exchange robots during the task introducing additional co-observations that can secure originally unsecured routes. We show that the planning of cross-trajectory co-observations can be transformed into a network flow problem and solved using traditional linear program technique. In the final part of the thesis, we show that the introduction of sub-teams also improves the multi-robot system's robustness to unplanned situations, allowing servicing unplanned online events without breaking the security requirements. This is achieved by a distributed task assignment algorithm based on consensus ADMM which can handle tasks with different priorities. The assignment result and security requirements are formulated as spatio-temporal schedules and guaranteed through control barrier function (CBF) based controls

    Design, Development, and Evaluation of Customized Electronics for Controlling a 5-DOF Magneto-Rheological Actuator Collaborative Robot

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    In recent years, Magneto-Rheological (MR) fluids has been used in various fields such as robotics, automotive, aerospace, etc. The most common use of the MR fluids is within a clutch-like mechanism, namely an MR clutch. When mechanical input is coupled to the input part of the MR clutch, the MR clutch provides a means of delivering this mechanical input to its output, through the MR fluids. The combination of the mechanical input device and the MR clutch is called an MR actuator. The MR actuator features inherently compliance owing to the characteristic of the MR fluids while also offering higher torque-to-mass and torque-to-inertia ratios over common actuators. As such, MR actuators are suitable candidates for human-safe and collaborative robots. The goal of this study is to design, develop and test customized electronic drivers that are compact and powerful to enable effective low-level control of the robot joints. The electronic drivers are responsible for sensor data processing, between-joint communication, supplying electric power, and executing control actions. The hardware design is optimized to handle transient current and voltage, and dissipate heat generated by components. Moreover, software development is based on μ C/OS-II real-time operating system to handle multiple time-critical tasks and to guarantee the stability and effectiveness of robot control system. A series of experiments are conducted to validate the designed hardware and software systems, and evaluate their performance

    Research on the Operating Characteristics of Floor Heating System with Residential EVI Air Source Heat Pump in China

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    Air source heat pump is considered a commendatory way to help solve the environmental problems resulting from coal-fired heating, especially in the cold region of China. The heat pump uses air as low-grade heat source, so the atmospherical temperature plays a key role in the operating performance of units. And the technology of economized vapor injection (EVI) is used to improve the performance in the low temperature condition. Beijing is one of the most typical cities in China cold region. Therefore, this paper took a residence in Beijing as the test site. A long-term and high-frequency monitoring was performed to investigate the operating characteristics and heating effect of floor heating system with EVI air source heat pump, and the economy was also analyzed. Equivalent carbon dioxide emission was also calculated to evaluate the carbon dioxide emission of such a heating system from cradle to grave. The results showed that the heating seasonal performance factor (HSPF) of the heating system in Beijing was 3.28, and the running condition was stable on the premise of satisfying the heating need of uses. Attentions were also paid to the behavior of residents. The irregularity revealed the apparent need and the energy saving awareness, which directly affected the power consumption
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