| 1. |
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| 2. |
- Chen, Xiaowen, et al.
(författare)
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Performance analysis of homogeneous on-chip large-scale parallel computing architectures for data-parallel applications
- 2015
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Limited. - 2090-0147 .- 2090-0155. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- On-chip computing platforms are evolving from single-core bus-based systems to many-core network-based systems, which are referred to as On-chip Large-scale Parallel Computing Architectures (OLPCs) in the paper. Homogenous OLPCs feature strong regularity and scalability due to its identical cores and routers. Data-parallel applications have their parallel data subsets that are handled individually by the same program running in different cores. Therefore, data-parallel applications are able to obtain good speedup in homogenous OLPCs. The paper addresses modeling the speedup performance of homogeneous OLPCs for data-parallel applications. When establishing the speedup performance model, the network communication latency and the ways of storing data of data-parallel applications are modeled and analyzed in detail. Two abstract concepts (equivalent serial packet and equivalent serial communication) are proposed to construct the network communication latency model. The uniform and hotspot traffic models are adopted to reflect the ways of storing data. Some useful suggestions are presented during the performance model's analysis. Finally, three data-parallel applications are performed on our cycle-accurate homogenous OLPC experimental platform to validate the analytic results and demonstrate that our study provides a feasible way to estimate and evaluate the performance of data-parallel applications onto homogenous OLPCs.
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| 3. |
- Ekström, Rickard, et al.
(författare)
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Grid Connection of Wave Power Farm Using an N-Level Cascaded H-Bridge Multilevel Inverter
- 2013
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Limited. - 2090-0147 .- 2090-0155. ; 2013, s. 9-
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Tidskriftsartikel (refereegranskat)abstract
- An N-level cascaded H-bridge multilevel inverter is proposed for grid connection of large wave power farms. The point-absorber wave energy converters are individually rectified and used as isolated DC-sources. The variable power characteristics of the wave energy converters are discussed, and a method of mitigating this issue is demonstrated. The complete power control system is given in detail and has been experimentally verified for a single-phase setup of the 9-level inverter. Theoretical expressions of the power sharing between multilevel cells are derived and show good correspondence with the experimental results.
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| 4. |
- Goncalves de Oliveira, Janaína, et al.
(författare)
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Battery Recharging Issue for a Two-Power-Level Flywheel System
- 2010
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Limited. - 2090-0147 .- 2090-0155. ; 2010, s. 470525-
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Tidskriftsartikel (refereegranskat)abstract
- A novel battery recharging system for an all-electric driveline comprising a flywheel with a permanent magnet double wound synchronous machine (motor/generator) is presented. The double winding enables two voltage levels and two different power levels. This topology supersedes other all-electric drivelines. The battery operates in a low-power regime supplying the average power whereas the flywheel delivers and absorbs power peaks, which are up to a higher order of magnitude. The topology presents new challenges for the power conversion system, which is the focus of this investigation. The main challenge is the control of the power flow to the battery when the vehicle is parked despite the decay of the flywheel machine voltage; which is dependent on its charge state, that is, rotational speed. The design and simulation of an unidirectional DC/DC buck/boost converter for a variable rotational speed flywheel is presented. Conventional power electronic converters are used in a new application, which can maintain a constant current or voltage on the battery side. Successful PI current control has been implemented and simulated, together with the complete closed loop system.
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| 5. |
- Lisova, Elena, et al.
(författare)
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Protecting Clock Synchronization : Adversary Detection through Network Monitoring
- 2016
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Limited. - 2090-0147 .- 2090-0155.
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Tidskriftsartikel (refereegranskat)abstract
- Today, industrial networks are often used for safetycritical applications with real-time requirements. The architecture of such applications usually has a time-triggered nature that has message scheduling as a core property. Real-time scheduling can be applied only in networks where nodes share the same notion of time, i.e., they are synchronized. Therefore, clock synchronization is one of the fundamental assets of industrial networks with real-time requirements. However, standards for clock synchronization, i.e., IEEE 1588, do not provide the required level of security. This raises the question about clock synchronization protection. In this paper we identify a way to break synchronization based on the IEEE 1588 standard by conducting a man-in-the-middle (MIM) attack followed by a delay attack. MIM attack can be accomplished through e.g., Address Resolution Protocol (ARP) poisoning. Using AVISPA tool we evaluate the potential to perform an ARP poisoning attack. Next, an analysis of the consequences of introducing delays is made, showing both that the attack can, indeed, break clock synchronization and that some design choices, such as a relaxed synchronization condition mode, delay bounding and using knowledge of environmental conditions, can be made to make the network more robust/resilient against these kinds of attacks. Lastly, network monitoring is proposed as a technique to detect anomalies introduced by an adversary performing attacks targeting clock synchronization. The monitoring capabilities are added to the network using a Configuration Agent, which, based on data obtained from the network, is able to detect an attack. The main contribution of the paper is a detailed problem description and evaluation of a security vulnerability in IEEE 1588 against delay attacks together with an evaluation of several approaches as possible mitigation techniques for the attack.
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| 6. |
- Manssour, Jawad, et al.
(författare)
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High-Rate Redundant Space-Time Coding
- 2010
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Limited. - 2090-0147 .- 2090-0155. ; 2010, s. 324138-
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Tidskriftsartikel (refereegranskat)abstract
- We present a new space-time encoderbased on packet-level redundancy which can increase the space-time encoder rate beyond unity without compromising diversitygains. A complementary low-complexity decoding algorithmbased on maximum ratio combining and successive interferencecancelation is further proposed. A major merit of the decodingalgorithm is that it allows to adaptively tradeoff betweendiversity and multiplexing gains based on the estimated channelparameters at the receiver without requiring any channel stateinformation at the transmitter. System level simulation resultsgive insight into the advantages of the proposed scheme whencompared to its Alamouti and MIMO multiplexing based onsingle value decomposition counterparts.
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| 7. |
- Ouassou, M., et al.
(författare)
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Reliability Analysis of Network Real-Time Kinematic
- 2018
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Limited. - 2090-0147 .- 2090-0155. ; 2018
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Tidskriftsartikel (refereegranskat)abstract
- The multistate reliability theory was applied to the network real-time kinematic (NRTK) data processing chain, where the qualities of the network corrections, baseline residuals, and the associated variance-covariance matrices are considered as the system state vectors. The state vectors have direct influence on the rover receiver position accuracy. The penalized honored stochastic averaged standard deviation (PHSASD) is used to map the NRTK sensitive data, represented by the states vectors to different levels of performance. The study shows that the improvement is possible by identification of critical components in the NRTK system and implementation of some parallelism that makes the system more robust.
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| 8. |
- Razzaq, Adil, et al.
(författare)
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Virtual Network Embedding : A Hybrid Vertex Mapping Solution for Dynamic Resource Allocation
- 2012
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Publishing Corporation. - 2090-0147 .- 2090-0155. ; :Article ID:358647, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Virtual network embedding (VNE) is a key area in network virtualization, and the overall purpose of VNE is to map virtualnetworks onto an underlying physical network referred to as a substrate. Typically, the virtual networks have certain demands,such as resource requirements, that need to be satisfied by the mapping process. A virtual network (VN) can be described in termsof vertices (nodes) and edges (links) with certain resource requirements, and, to embed a VN, substrate resources are assigned tothese vertices and edges. Substrate networks have finite resources and utilizing them efficiently is an important objective for a VNEmethod. This paper analyzes two existing vertex mapping approaches—one which only considers if enough node resources areavailable for the current VN mapping and one which considers to what degree a node already is utilized by existing VN embeddingsbefore doing the vertex mapping. The paper also proposes a new vertex mapping approach which minimizes complete exhaustionof substrate nodes while still providing good overall resource utilization. Experimental results are presented to show under whatcircumstances the proposed vertex mapping approach can provide superior VN embedding properties compared to the otherapproaches.
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| 9. |
- Sardis, Fragkiskos, et al.
(författare)
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Investigating a Mobility-Aware QoS Model for Multimedia Streaming Rate Adaptation
- 2015
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Ingår i: Journal of Electrical and Computer Engineering. - New York, NY : Hindawi Publishing Corporation. - 2090-0147 .- 2090-0155. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- Supporting high quality multimedia streaming on wireless devices poses several challenges compared to wired networks due to the high variance in network performance encountered in the mobile environment. Although rate adaptation is commonly used in multimedia applications to compensate for fluctuations in network performance, it is a reactive mechanism which is not aware of the frequently changing connectivity that may occur on mobile devices. This paper proposed a performance evaluation model for multimedia streaming applications that is aware of user mobility and network performance. We presented an example of mathematical solution to the model and demonstrated the functionality using common mobility and connectivity examples that may be found in an urban environment. The proposed model is evaluated based on this functionality and how it may be used to enhance application performance. © 2015 Fragkiskos Sardis et al.
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| 10. |
- Somarriba, Oscar, et al.
(författare)
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Detection and Visualization of Android Malware Behavior
- 2016
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Ingår i: Journal of Electrical and Computer Engineering. - : Hindawi Publishing Corporation. - 2090-0147 .- 2090-0155. ; 2016
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Tidskriftsartikel (refereegranskat)abstract
- Malware analysts still need to manually inspect malware samples that are considered suspicious by heuristic rules. They dissect software pieces and look for malware evidence in the code. The increasing number of malicious applications targeting Android devices raises the demand for analyzing them to find where the malcode is triggered when user interacts with them. In this paper a framework to monitor and visualize Android applications’ anomalous function calls is described. Our approach includes platform-independent application instrumentation, introducing hooks in order to trace restricted API functions used at runtime of the application. These function calls are collected at a central server where the application behavior filtering and a visualization take place. This can help Android malware analysts in visually inspecting what the application under study does, easily identifying such malicious functions.
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