59 research outputs found

    Invited Abstract: A Simulation Package for Energy Consumption of Content Delivery Networks (CDNs)

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    Content Delivery Networks (CDNs) are becoming an integral part of the future generation Internet. Traditionally, these networks have been designed with the goals of traffic offload and the improvement of users' quality of experience (QoE), but the energy consumption is also becoming an indispensable design factor for CDNs to be a sustainable solution. To study and improve the CDN architectures using this new design metric, we are planning to develop a generic and flexible simulation package in OMNet++. This package is aimed to render a holistic view about the CDN energy consumption behaviour by incorporating the state-of-the-art energy consumption models proposed for the individual elements of CDNs (e.g. servers, routers, wired and wireless links, wireless devices, etc.) and for the various Internet contents (web pages, files, streaming video, etc.).Comment: Published in: A. F\"orster, C. Minkenberg, G. R. Herrera, M. Kirsche (Eds.), Proc. of the 2nd OMNeT++ Community Summit, IBM Research - Zurich, Switzerland, September 3-4, 2015, arXiv:1509.03284, 201

    Reliability and Efficiency of Vehicular Network Applications

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    The DSRC/WAVE initiative is forecast to enable a plethora of applications, classified in two broad types of safety and non-safety applications. In the former type, the reliability performance is of tremendous prominence while, in the latter case, the efficiency of information dissemination is the key driving factor. For safety applications, we adopt a systematic approach to analytically investigate the reliability of the communication system in a symbiotic relationship with the host system comprising a vehicular traffic system and radio propagation environment. To this aim, the¬ interference factor is identified as the central element of the symbiotic relationship. Our approach to the investigation of interference and its impacts on the communication reliability departs from previous studies by the degree of realism incorporated in the host system model. In one dimension, realistic traffic models are developed to describe the vehicular traffic behaviour. In a second dimension, a realistic radio propagation model is employed to capture the unique signal propagation aspects of the host system. We address the case of non-safety applications by proposing a generic framework as a capstone architecture for the development of new applications and the efficiency evaluation of existing ones. This framework, while being independent from networking technology, enables accurate characterization of the various information dissemination tasks that a node performs in cooperation with others. As the central element of the framework, we propose a game theoretic model to describe the interaction of meeting nodes aiming to exchange information of mutual or social interests. An adaptive mechanism is designed to enable a mobile node to measure the social significance of various information topics, which is then used by the node to prioritize the forwarding of information objects

    Carbon Nanotube-Based UV-Curable Nanocomposite Coatings

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    This chapter covers the preparation and properties of ultraviolet (UV)-curable nanocomposite containing carbon nanotubes as fillers. UV-curing technology is of particular interest due to its unique properties such as rapid curing process and solvent-free formulation. Alongside with the advantages of utilizing this curing method, carbon nanotubes undergo benefits including high aspect ratio, high transparency, and good mechanical properties. Carbon nanotubes (CNTs) are hollow cylindrical shaped configuration; consist of one, two, or more walls with an interlayer of non-covalent van der Waals force acting among the carbon atoms of various walls. Besides influencing the UV curing process, the CNTs loaded UV-curable nanocomposites sustain modified surface, thermal, mechanical, physical, and conductive properties which are discussed in this chapter. The health and safety concerns of using these classes of nanocomposite are further discussed

    Comparison of levofloxacin versus clarithromycin efficacy in the eradication of Helicobacter pylori infection

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    Background: Helicobacter pylori (H.pylori) infection causes multiple upper gastrointestinal diseases but optimal therapeutic regimen which can eradicate infection in all the cases has not yet been defined. This study was designed to evaluate the efficacy of triple levofloxacin-based versus clarithromycin-based therapy. Methods: In this open-label randomized clinical trial study 120 patients who had esophagogastroduodenoscopy (EGD) with positive rapid urease test (RUT) were enrolled and divided into 2 groups. Case group was treated with levofloxacin (500 mg daily) plus amoxicillin (1 gr twice a day) plus omeprazole (20 mg daily) for 2 weeks. Control group was treated with clarithromycin (500 mg twice a day) plus omeprazole (20 mg daily) for 2 weeks. After the main course of treatment, they received maintenance treatment with omeprazole for 4 weeks. Stool antigen test was performed on them after two weeks of not having any medicine. Results: H.pylori eradication (intention to treat analysis) was successful in 75% of case group and 51.7% of control group showing a significant difference (P=0.008). H.p infection eradication (per-protocol analysis) was successful in 80.4% in case group and 57.4%% in control group showing significant difference (P=0.009). Drugs adverse effects causing discontinuation treatment were seen in 5% of case group and 3.3% of control group which have not shown a significant difference between the two groups (P=0.648). Conclusion: Triple therapy with levofloxacin-based regimen has better efficacy than clarithromycin-based regimen and as safe as it is. Keywords: Helicobacter pylori, Dyspepsia, Peptic ulcer, Rapid urease test, Stool antige

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    Application of agent based modeling to simulate diffusion of energy saving policies among occupants based on bass diffusion model

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    Providing feedback to occupants will affect their energy consumption patterns to save more energy and reduce emission. Currently, energy simulation software programs such as eQUEST and Energy Plus are the most common software programs for simulating energy consumption in buildings. Although these software programs help designers to have a better understanding about building energy consumption in the design phase, the obtained results display some deviations with actual statistical data. The reason of these deviations can be attributed to the lack in consideration of the effects that occupants can have on each other during working hours. Also, energy managers cannot have a reliable comparison about efficiency of different energy saving policies due to abandoning these occupancy behavior factors. The current paper proposes an agent-based approach to simulate the impact of occupancy behavior on energy consumption and emission production in commercial buildings. Two models were developed in this study to investigate potential energy efficiency improvement through change in occupant’s behaviorial pattern over time. The results showed that there is a considerable potential in energy preservation and emission reduction by providing feedback to occupants

    The Effect of Hidden Terminal Interference on Safety-Critical Traffic in Vehicular Ad Hoc Networks

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    In Vehicular Ad hoc NETworks (VANETs) where safety applications rely on broadcast communications, the hidden terminal problem can severely impact the reliability of these applications. Particularly, in forced flow traffic scenarios as the primary case of safety-critical situations, reliability is paramount for inter-vehicle communications to be useful. Not surprising, in these scenarios, the hidden terminal effect is expected to be especially severe, mainly due to the high vehicle density. Accurate characterization of this problem and the extent of its impact on reliability requires that realistic aspects of the traffic system and radio propagation environment are taken into consideration. In this paper, we investigate the hidden terminal problem under realistic conditions with focus on safety-critical traffic scenarios. A state-of-the-art radio propagation model targeted for vehicular environments is employed to characterise the interference power induced by hidden nodes. Our combinations of experiments with various velocities and lane configurations show that, in a road segment operating at full capacity, the hidden terminal interference causes a significant decline in the reachable distance of safety messages, leading to broadcast coverage smaller than safety applications requirements
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