| 51. |
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| 52. |
- Song, Haokun, et al.
(författare)
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Machine-learning-based method for fiber-bending eavesdropping detection
- 2023
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 48:12, s. 3183-3186
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we present a scheme for detecting fiber-bending eavesdropping based on feature extraction and machine learning (ML). First, 5-dimensional features from the time-domain signal are extracted from the optical signal, and then a long short-term memory (LSTM) network is applied for eavesdropping and normal event classification. Experimental data are collected from a 60km single-mode fiber transmission link with eavesdropping implemented by a clip-on coupler. Results show that the proposed scheme achieves a 95.83% detection accuracy. Furthermore, since the scheme focuses on the time-domain waveform of the received optical signal, additional devices and a special link design are not required.
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| 53. |
- Tang, Xiaopeng, et al.
(författare)
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Run-to-Run Control for Active Balancing of Lithium Iron Phosphate Battery Packs
- 2020
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 35:2, s. 1499-1512
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Tidskriftsartikel (refereegranskat)abstract
- © 1986-2012 IEEE. Lithium iron phosphate battery packs are widely employed for energy storage in electrified vehicles and power grids. However, their flat voltage curves rendering the weakly observable state of charge are a critical stumbling block for charge equalization management. This paper focuses on the real-time active balancing of series-connected lithium iron phosphate batteries. In the absence of accurate in situ state information in the voltage plateau, a balancing current ratio (BCR) based algorithm is proposed for battery balancing. Then, BCR-based and voltage-based algorithms are fused, responsible for the balancing task within and beyond the voltage plateau, respectively. The balancing process is formulated as a batch-based run-to-run control problem, as the first time in the research area of battery management. The control algorithm acts in two timescales, including timewise control within each batch run and batchwise control at the end of each batch. Hardware-in-the-loop experiments demonstrate that the proposed balancing algorithm is able to release 97.1% of the theoretical capacity and can improve the capacity utilization by 5.7% from its benchmarking algorithm. Furthermore, the proposed algorithm can be coded in C language with the binary code in 118 328 bytes only and, thus, is readily implementable in real time.
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| 54. |
- Tiloca, Marco, et al.
(författare)
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SARDOS: Self-Adaptive Reaction against Denial of Service in the Internet of Things
- 2018
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Konferensbidrag (refereegranskat)abstract
- Denial of Service (DoS) is a common and severe security issue in computer networks. Typical DoS attacks overload servers with bogus requests, induce them to worthlessly commit resources, and even make them unable to serve legitimate clients. This is especially relevant in Internet of Things scenarios, where servers are particularly exposed and often equipped with limited resources. Although most countermeasures focus on detection and mitigation, they do not react to dynamically adapt victims' behavior, while at the same time preserving service availability. This paper presents SARDOS, a reactive security service that leverages detection mechanisms from different communication layers, and adaptively changes the operative behavior of victim servers while preserving service availability. We experimentally evaluated SARDOS with a prototype implementation running on an underclocked Raspberry Pi server. Our results show that, when running SARDOS, a server under attack displays considerably lower memory and CPU usage, while still ensuring (best-effort) fulfillment of legitimate requests.
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| 55. |
- Vega-Barbas, Mario, et al.
(författare)
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Adaptive Software Architecture for Confident Homecare in the Digital Home
- 2014
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Konferensbidrag (refereegranskat)abstract
- Smart spaces foster the development of more natural and suitable forms of human-computer interaction taking advantage of customization possibilities offered by the home. The interaction chances of the Digital Home, as a special type of smart space, have a special interest in fields where the acceptance of new technologies is low and restrictive. Homecare is a discipline where this acceptance is more problematic. The integration of digital home design patterns in homecare solutions should enhance the final acceptance of users. In this position paper, we present the main challenges identified from the literature for the successful implementation of homecare solutions in smart spaces and the design of a software architecture that models entities and functionalities involved in solving these challenges.
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| 56. |
- Vosoogh, Abbas, 1984
(författare)
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Compact RF Integration and Packaging Solutions Based on Metasurfaces for Millimeter-Wave Applications
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The millimeter-wave frequency range has got a lot of attention over the past few years because it contains unused frequency spectrum resources that are suitable for delivering Gbit/s end-user access in areas with high user density. Due to the limited output power that the current RF active components can deliver in millimeter-wave frequencies, antennas with the features of low profile, high gain, high efficiency and low cost are needed to compensate free space path loss and increase the communication distance for the emerging high data rate wireless systems. Moreover, it is desired to have a compact system by integration of the antenna with passive and active components at high frequencies. In order to move towards millimeter-wave frequencies we need to face significant hardware challenges, such as active and passive components integration, packaging problems, and cost-effective manufacturing techniques. The gap waveguide technology shows interesting characteristics as a new waveguide structure. The main goal of this thesis is to demonstrate the advantages of gap waveguide technology as an alternative to the traditional guiding structures to overcome the problem of good electrical contact due to mechanical assembly with low loss. This thesis mainly focuses on high-gain planar array antenna design, integration with passive and active components, and packaging based on gap waveguide technology. We introduce several low-profile multilayer corporate-fed slot array antennas with high gain, high efficiency and wide impedance bandwidth operating at the millimeter-wave frequency band. A system demonstration consisting of two compact integrated antenna-diplexer and Tx/Rx MMICs for Frequency-division duplex (FDD) low latency wireless backhaul links at E-band is presented to show the advantages of gap waveguide technology in building a complete radio front-end. Moreover, the use of several new manufacturing methods, such as die-sink Electric Discharge Machining (EDM), direct metal 3-D printing, and micro-molding are evaluated to fabricate gap waveguide components in a more effective way. Furthermore, a novel air-filled transmission line, so-called multi-layer waveguide (MLW), that exhibits great advantages such as low-cost, simple fabrication, and low loss, even for frequencies beyond 100 GHz, is presented for the first time. To constitute an MLW structure, a rectangular waveguide transmission line is formed by stacking several thin metal layers without any electrical and galvanic contact requirement among the layers. The proposed concept could become a suitable approach to design millimeter-wave high-performance passive waveguide components, and to be used in active and passive components integration ensuring mass production at the same time.
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| 57. |
- Xiong, Binyu, et al.
(författare)
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A flow-rate-aware data-driven model of vanadium redox flow battery based on gated recurrent unit neural network
- 2023
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Ingår i: Journal of Energy Storage. - 2352-152X. ; 74
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Tidskriftsartikel (refereegranskat)abstract
- The vanadium redox flow battery (VRB) system involves complex multi-physical and multi-timescale interactions, where the electrolyte flow rate plays a pivotal role in both static and dynamic performance. Traditionally, fixed flow rates have been employed for operational convenience. However, in today's highly dynamic energy market environment, adjusting flow rates based on operating conditions can provide significant advantages for improving VRB energy conversion efficiency and cost-effectiveness. Unfortunately, incorporating the electrolyte flow rate into conventional multi-physical models is overly complex for VRB management and control systems, as real-time operations demand low-computational and low-complexity models for onboard functionalities. This paper introduces a novel data-driven approach that integrates flow rates into VRB modeling, enhancing data processing capabilities and prediction accuracy of VRB behaviors. The proposed model adopts a gated recurrent unit (GRU) neural network as its fundamental framework, exhibiting exceptional proficiency in capturing VRB's nonlinear voltage segments. The GRU network structure is carefully designed to optimize the predictive ability of the model, with flow rate considered as a crucial input parameter to account for its influence on VRB behavior. Model refinement involves analyzing well-designed simulation results obtained during VRB operations under various flow rates. Laboratory experiments were also designed and conducted, covering different conditions of currents and flow rates to validate the proposed data-driven modeling method. Comparative analyses were performed against several state-of-the-art algorithms, including equivalent circuit models and other data-driven models, demonstrating the superiority of the proposed GRU-based VRB model considering flow rates. Thanks to the GRU's outstanding capability in processing time series data, the proposed model delivers impressively accurate terminal voltage predictions with a low error margin of no more than 0.023 V (1.3%) under wide operating ranges. These results indicate the efficacy and robustness of the proposed approach, highlighting the novelty and significance of accounting for flow rates in accurate VRB modeling for management and control system design.
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| 58. |
- Ahmed, J., et al.
(författare)
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Automated diagnostic of virtualized service performance degradation
- 2018
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Ingår i: Proceedings 2018 IEEE/IFIP Network Operations and Management Symposium, NOMS 2018. - New York : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- Service assurance for cloud applications is a challenging task and is an active area of research for academia and industry. One promising approach is to utilize machine learning for service quality prediction and fault detection so that suitable mitigation actions can be executed. In our previous work, we have shown how to predict service-level metrics in real-time just from operational data gathered at the server side. This gives the service provider early indications on whether the platform can support the current load demand. This paper provides the logical next step where we extend our work by proposing an automated detection and diagnostic capability for the performance faults manifesting themselves in cloud and datacenter environments. This is a crucial task to maintain the smooth operation of running services and minimizing downtime. We demonstrate the effectiveness of our approach which exploits the interpretative capabilities of Self- Organizing Maps (SOMs) to automatically detect and localize different performance faults for cloud services.
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| 59. |
- Eriksson, Martin, et al.
(författare)
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Monitoring and modelling open compute servers
- 2017
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Ingår i: Proceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society. - Piscataway, NJ : Institute of Electrical and Electronics Engineers Inc.. - 9781538611272 ; , s. 7177-7184, s. 7177-7184
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Konferensbidrag (refereegranskat)abstract
- Energy efficient control of server rooms in modern data centers can help reducing the energy usage of this fast growing industry. Efficient control, however, cannot be achieved without: i) continuously monitoring in real-time the behavior of the basic thermal nodes within these infrastructures, i.e., the servers; ii) analyzing the acquired data to model the thermal dynamics within the data center. Accurate data and accurate models are indeed instrumental for implementing efficient data centers cooling strategies. In this paper we focus on a class of Open Compute Servers, designed in an open-source fashion and currently deployed by Facebook. We thus propose a set of methods for collecting real-time data from these platforms and a control-oriented model describing the thermal dynamics of the CPUs and RAMs of these servers as a function of both manipulable and exogenous inputs (e.g., the CPU utilization levels and the air mass flow produced by the server's fans). We identify the parameters of this model from real data and make the results available to other researchers.
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| 60. |
- Khan, Muhammad Sikandar Lal, 1988-, et al.
(författare)
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Face-off : A face reconstruction technique for virtual reality (VR) scenarios
- 2016
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Ingår i: 14th European Conference on Computer Vision, ECCV 2016. - Cham : Springer. - 9783319466033 - 9783319466040 ; , s. 490-503
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Konferensbidrag (refereegranskat)abstract
- Virtual Reality (VR) headsets occlude a significant portion of human face. The real human face is required in many VR applications, for example, video teleconferencing. This paper proposes a wearable camera setup-based solution to reconstruct the real face of a person wearing VR headset. Our solution lies in the core of asymmetrical principal component analysis (aPCA). A user-specific training model is built using aPCA with full face, lips and eye region information. During testing phase, lower face region and partial eye information is used to reconstruct the wearer face. Online testing session consists of two phases, (i) calibration phase and (ii) reconstruction phase. In former, a small calibration step is performed to align test information with training data, while the later uses half face information to reconstruct the full face using aPCAbased trained-data. The proposed approach is validated with qualitative and quantitative analysis.
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