3,571 research outputs found

    Adaptive Sampling in Particle Image Velocimetry

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    Discriminative Scale Space Tracking

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    Accurate scale estimation of a target is a challenging research problem in visual object tracking. Most state-of-the-art methods employ an exhaustive scale search to estimate the target size. The exhaustive search strategy is computationally expensive and struggles when encountered with large scale variations. This paper investigates the problem of accurate and robust scale estimation in a tracking-by-detection framework. We propose a novel scale adaptive tracking approach by learning separate discriminative correlation filters for translation and scale estimation. The explicit scale filter is learned online using the target appearance sampled at a set of different scales. Contrary to standard approaches, our method directly learns the appearance change induced by variations in the target scale. Additionally, we investigate strategies to reduce the computational cost of our approach. Extensive experiments are performed on the OTB and the VOT2014 datasets. Compared to the standard exhaustive scale search, our approach achieves a gain of 2.5% in average overlap precision on the OTB dataset. Additionally, our method is computationally efficient, operating at a 50% higher frame rate compared to the exhaustive scale search. Our method obtains the top rank in performance by outperforming 19 state-of-the-art trackers on OTB and 37 state-of-the-art trackers on VOT2014.Comment: To appear in TPAMI. This is the journal extension of the VOT2014-winning DSST tracking metho

    Microgrids/Nanogrids Implementation, Planning, and Operation

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    Today’s power system is facing the challenges of increasing global demand for electricity, high-reliability requirements, the need for clean energy and environmental protection, and planning restrictions. To move towards a green and smart electric power system, centralized generation facilities are being transformed into smaller and more distributed ones. As a result, the microgrid concept is emerging, where a microgrid can operate as a single controllable system and can be viewed as a group of distributed energy loads and resources, which can include many renewable energy sources and energy storage systems. The energy management of a large number of distributed energy resources is required for the reliable operation of the microgrid. Microgrids and nanogrids can allow for better integration of distributed energy storage capacity and renewable energy sources into the power grid, therefore increasing its efficiency and resilience to natural and technical disruptive events. Microgrid networking with optimal energy management will lead to a sort of smart grid with numerous benefits such as reduced cost and enhanced reliability and resiliency. They include small-scale renewable energy harvesters and fixed energy storage units typically installed in commercial and residential buildings. In this challenging context, the objective of this book is to address and disseminate state-of-the-art research and development results on the implementation, planning, and operation of microgrids/nanogrids, where energy management is one of the core issues

    Adaptive Performance and Power Management in Distributed Computing Systems

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    The complexity of distributed computing systems has raised two unprecedented challenges for system management. First, various customers need to be assured by meeting their required service-level agreements such as response time and throughput. Second, system power consumption must be controlled in order to avoid system failures caused by power capacity overload or system overheating due to increasingly high server density. However, most existing work, unfortunately, either relies on open-loop estimations based on off-line profiled system models, or evolves in a more ad hoc fashion, which requires exhaustive iterations of tuning and testing, or oversimplifies the problem by ignoring the coupling between different system characteristics (\ie, response time and throughput, power consumption of different servers). As a result, the majority of previous work lacks rigorous guarantees on the performance and power consumption for computing systems, and may result in degraded overall system performance. In this thesis, we extensively study adaptive performance/power management and power-efficient performance management for distributed computing systems such as information dissemination systems, power grid management systems, and data centers, by proposing Multiple-Input-Multiple-Output (MIMO) control and hierarchical designs based on feedback control theory. For adaptive performance management, we design an integrated solution that controls both the average response time and CPU utilization in information dissemination systems to achieve bounded response time for high-priority information and maximized system throughput in an example information dissemination system. In addition, we design a hierarchical control solution to guarantee the deadlines of real-time tasks in power grid computing by grouping them based on their characteristics, respectively. For adaptive power management, we design MIMO optimal control solutions for power control at the cluster and server level and a hierarchical solution for large-scale data centers. Our MIMO control design can capture the coupling among different system characteristics, while our hierarchical design can coordinate controllers at different levels. For power-efficient performance management, we discuss a two-layer coordinated management solution for virtualized data centers. Experimental results in both physical testbeds and simulations demonstrate that all the solutions outperform state-of-the-art management schemes by significantly improving overall system performance

    System Support For Stream Processing In Collaborative Cloud-Edge Environment

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    Stream processing is a critical technique to process huge amount of data in real-time manner. Cloud computing has been used for stream processing due to its unlimited computation resources. At the same time, we are entering the era of Internet of Everything (IoE). The emerging edge computing benefits low-latency applications by leveraging computation resources at the proximity of data sources. Billions of sensors and actuators are being deployed worldwide and huge amount of data generated by things are immersed in our daily life. It has become essential for organizations to be able to stream and analyze data, and provide low-latency analytics on streaming data. However, cloud computing is inefficient to process all data in a centralized environment in terms of the network bandwidth cost and response latency. Although edge computing offloads computation from the cloud to the edge of the Internet, there is not a data sharing and processing framework that efficiently utilizes computation resources in the cloud and the edge. Furthermore, the heterogeneity of edge devices brings more difficulty to the development of collaborative cloud-edge applications. To explore and attack the challenges of stream processing system in collaborative cloudedge environment, in this dissertation we design and develop a series of systems to support stream processing applications in hybrid cloud-edge analytics. Specifically, we develop an hierarchical and hybrid outlier detection model for multivariate time series streams that automatically selects the best model for different time series. We optimize one of the stream processing system (i.e., Spark Streaming) to reduce the end-to-end latency. To facilitate the development of collaborative cloud-edge applications, we propose and implement a new computing framework, Firework that allows stakeholders to share and process data by leveraging both the cloud and the edge. A vision-based cloud-edge application is implemented to demonstrate the capabilities of Firework. By combining all these studies, we provide comprehensive system support for stream processing in collaborative cloud-edge environment

    AUTOMATED HIGH-SPEED MONITORING OF METAL TRANSFER FOR REAL-TIME CONTROL

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    In the novel Double Electrode Gas Metal Arc Welding (DE-GMAW), the transfer of the liquid metal from the wire to the work-piece determines the weld quality and for applications where the precision is critical, the metal transfer process needs to be monitored and controlled to control the diameter, trajectory, and transfer rate of the droplet of liquid metal. In this doctoral research work, the traditional methods of tracking, Correlation, Least Square Matching (LSM) and Kalman Filtering (KF), are tried first. All of them failed due to the poor quality of the metal transfer image and the variety of the droplet. Then several novel image processing algorithms, Brightness Based Separation Algorithm (BBSA), Brightness and Subtraction Based Separation Algorithm (BSBSA) and Brightness Based Selection and Edge Detection Based Enhancement Separation Algorithm (BBSEDBESA), are proposed to compute the size and locate the position of the droplet. Experimental results verified that the proposed algorithms can automatically locate the droplets and compute the droplet size with an adequate accuracy. Since the final objective is to automatically process the metal transfer in real time, a real time processing system is implemented and the details are described. In traditional Gas Metal Arc Welding (GMAW), the famous laser back-lighting technique has been widely used to image the metal transfer process. Due to laser imaging systems complexity, it is too inconvenient for practical applications. In this doctoral research work, a simplified laser imaging system is proposed and two effective image algorithms, Probability Based Double Thresholds Separation Algorithm and Edge Based Separation Algorithm, are proposed to process the corresponding captured metal transfer images. Experimental results verified that the proposed simplified laser back-light imaging system and image processing algorithms can be used for real time processing of metal transfer images

    An experimental study of the feasibility of phase‐based video magnification for damage detection and localisation in operational deflection shapes

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    Optical measurements from high‐speed, high‐definition video recordings can be used to define the full‐field dynamics of a structure. By comparing the dynamic responses resulting from both damaged and undamaged elements, structural health monitoring can be carried out, similarly as with mounted transducers. Unlike the physical sensors, which provide point‐wise measurements and a limited number of output channels, high‐quality video recording allows very spatially dense information. Moreover, video acquisition is a noncontact technique. This guarantees that any anomaly in the dynamic behaviour can be more easily correlated to damage and not to added mass or stiffness due to the installed sensors. However, in real‐life scenarios, the vibrations due to environmental input are often so small that they are indistinguishable from measurement noise if conventional image‐based techniques are applied. In order to improve the signal‐to‐noise ratio in low‐amplitude measurements, phase‐based motion magnification has been recently proposed. This study intends to show that model‐based structural health monitoring can be performed on modal data and time histories processed with phase‐based motion magnification, whereas unamplified vibrations would be too small for being successfully exploited. All the experiments were performed on a multidamaged box beam with different damage sizes and angles

    Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes

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    The book documents 25 papers collected from the Special Issue “Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes”, highlighting recent research trends in complex industrial processes. The book aims to stimulate the research field and be of benefit to readers from both academic institutes and industrial sectors
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