Search results for "performance evaluation"
showing 10 items of 44 documents
SHARP: Environment and Person Independent Activity Recognition with Commodity IEEE 802.11 Access Points
2022
In this article we present SHARP, an original approach for obtaining human activity recognition (HAR) through the use of commercial IEEE 802.11 (Wi-Fi) devices. SHARP grants the possibility to discern the activities of different persons, across different time-spans and environments. To achieve this, we devise a new technique to clean and process the channel frequency response (CFR) phase of the Wi-Fi channel, obtaining an estimate of the Doppler shift at a radio monitor device. The Doppler shift reveals the presence of moving scatterers in the environment, while not being affected by (environment-specific) static objects. SHARP is trained on data collected as a person performs seven differe…
Performance evaluation of OpenFlow enabled Commodity and Raspberry-pi Wireless Routers
2017
Software defined network (SDN) allows the decoupling of data and control plane for dynamic and scalable network management. SDN is usually associated with OpenFlow protocol which is a standard interface that enables the network controllers to determine the path of network packets across a network of switches. In this paper, we evaluate openflow performance using commodity wireless router and raspberry pi with two different SDN controllers. Our test setup consists of wired and wireless client devices connected to openflow enabled commodity wireless router and raspberry pi. All clients used traffic generator tool to transmits data to a sink server host. The results are promising and paves the…
The Investment Performance of U.S. Islamic Mutual Funds
2020
Islamic investment funds have become increasingly important because of high demand from many investors, including those outside the Muslim investment community. This article compares the performance and risk sensitivity of Islamic mutual funds in the United States with that of their conventional peers. This article also analyzes the performance of Islamic funds, and compares this performance with that of socially responsible investment (SRI) mutual funds. Capital Asset Pricing Model (CAPM)-based methodology was used for the analysis. The results suggest that over the entire study period (1987&ndash
A grid representation for distributed virtual environments
2004
Fast Internet connections and the widespread use of high performance graphic cards are making Distributed Virtual Environments (DVE) very common nowadays. The architecture and behavior of these systems are very similar to new grid computing applications where concepts such as sharing and high scalability are extremely exploited. However, there are several key issues in these systems that should still be improved in order to design a scalable and cost-effective DVE system. One of these key issues is the partitioning problem. This problem consists of efficiently assigning clients (3-D avatars) to the arbiters (servers) in the system. As an alternative to the ad-hoc heuristic proposed in the l…
Remarks on IEEE 802.11 DCF performance analysis
2005
This letter presents a new approach to evaluate the throughput/delay performance of the 802.11 distributed coordination function (DCF). Our approach relies on elementary conditional probability arguments rather than bidimensional Markov chains (as proposed in previous models) and can be easily extended to account for backoff operation more general than DCF's one.
A Performance Evaluation of Fusion Techniques for Spatio-Temporal Saliency Detection in Dynamic Scenes
2013
International audience; Visual saliency is an important research topic in computer vision applications, which helps to focus on regions of interest instead of processing the whole image. Detecting visual saliency in still images has been widely addressed in literature. However, visual saliency detection in videos is more complicated due to additional temporal information. A spatio-temporal saliency map is usually obtained by the fusion of a static saliency map and a dynamic saliency map. The way both maps are fused plays a critical role in the accuracy of the spatio-temporal saliency map. In this paper, we evaluate the performances of different fusion techniques on a large and diverse datas…
The Performance Evaluation of Polytechnic Higher Education Institutions: Tensions and Reconfigurations Resulting from the Adoption of Specific Metrics
2017
Aligned with the binary structure of the higher education system in Portugal, divided into universities and polytechnics, the Government acknowledged, in 2014, the need to identify distinct performance indicators/metrics aiming at a more accurate assessment of the effect and quality of the action developed by Higher Education Institutions (HEIs). For the Polytechnic Higher Education Institutions (PHEIs) it was necessary to define «(...) performance indicators that address the production, transfer and diffusion of knowledge» (FCT, 2014: 1), aiming to measure «(...) the applied research and the cultural production activities as well as their impact on the region where they [PHEIs] are located…
MAC Protocols for Wake-up Radio: Principles, Modeling and Performance Analysis
2018
[EN] In wake-up radio (WuR) enabled wireless sensor networks (WSNs), a node triggers a data communication at any time instant by sending a wake-up call (WuC) in an on-demand manner. Such wake-up operations eliminate idle listening and overhearing burden for energy consumption in duty-cycled WSNs. Although WuR exhibits its superiority for light traffic, it is inefficient to handle high traffic load in a network. This paper makes an effort towards improving the performance of WuR under diverse load conditions with a twofold contribution. We first propose three protocols that support variable traffic loads by enabling respectively clear channel assessment (CCA), backoff plus CCA, and adaptive …
An Experimental Characterization of Time of Arrival Accuracy for Time Synchronization of Medium Voltage Smart Grid Solutions
2019
The time synchronization of smart grid devices is a critical feature for the successful application of advanced grid monitoring and control techniques. Synchronization mechanisms based on the accurate estimation of the Time of Arrival (ToA) of network messages - sent over power line cables - are a promising solution to achieve synchronization tasks over distribution lines. In this paper, a chirp-based synchronization technique over the Medium Voltage (MV) grid has been proposed and characterized. Such approach has the benefit of not requiring the installation of a dedicated infrastructure, thanks to the exploitation of power distribution lines for the transmission of time synchronization da…
Performance Analysis in Spatially Correlated IEEE 802.11 Networks
2012
Wireless mesh networks are difficult to be characterized, especially under multi-hop traffic streams. The problem is that the local view of the channel and the correlation between the buffers of consecutive nodes in a stream path make complicated the identification of the contention level perceived by each station along the time. Such a figure is used in the models based on the so called decoupling assumption for evaluating the final scheduling of simultaneous channel access grants. In this paper we propose a simplified mesh network model focused on capturing the correlation due to the network topology and traffic routes rather than the access protocol state at each node. To this purpose, w…