70 research outputs found
Experimental uncertainty of measured entropy production with pulsed laser PIV and planar laser induced fluorescence
No full textThe article develops an uncertainty analysis for a newly measured variable of local entropy production. Entropy production is measured with post-processing and spatial differencing of measured velocities from particle image velocimetry (PIV), as well as temperatures obtained from planar laser induced fluorescence (PLIF). Measurement uncertainties of fluid velocity depend on the time interval between laser pulses, width of the camera view and other factors. Bias errors are related to elementary bias components and sensitivity coefficients in the uncertainty analysis. The precision errors use a confidence coefficient of 2 for a 95% confidence interval. The newly developed measurement technique and uncertainty analysis are successfully applied to pressure-driven channel flow and buoyancy-driven free convection in a square enclosure.Natural Sciences and Engineering Research Council of CanadaUniversity of Manitoba Graduate FellowshipCFI (Canada Foundation for Innovation)WED (Western Economic Diversification
An Analysis of Collaborative Attacks on Mobile Ad hoc Networks
No full textA Mobile Ad hoc Network (MANET) consists of a set of communicating wireless mobile nodes or devices that do not have any form of fixed infrastructure or centralized authority. The security in MANET has become a significant and active topic within the research community. This is because of high demand in sharing streaming video and audio in various applications, one MANET could be setup quickly to facilitate communications in a hostile environment such as battlefield or emergency situation likes disaster rescue operation. In spite of the several attacks aimed at specific nodes in MANET that have been uncovered, some attacks involving multiple nodes still receive little attention. A reason behind this is because people make use of security mechanisms applicable to wired networks in MANET and overlook the security measures that apply to MANET. Furthermore, it may also have to do with the fact that no survey or taxonomy has been done to clarify the characteristics of different multiple node attacks. This thesis addresses the aforementioned gap by providing a proper definition and categorization of collaborative attacks against MANET from the various multiple node attacks found. Simulation using OPNET Modeler was used to investigate the performance impact of a collaborative blackhole attack on a mobile ad hoc network. Network throughput, packet delivery ratio and end-to-end delay are the performance metrics used in our result analysis. Based on the analyses of performance metrics made, we realised the consequences of a collaborative blackhole attack on MANET. In order to prevent or reduce these consequences, we also discuss a number of mitigation plans to counteract the different kinds of collaborative attacks. Keywords: MANET, Collaborative Attacks, Multiple Node, Blackhole.Contact Information: Author(s): Cong Hoan Vu Address: Folkparksvägen 19:08, 372 40 Ronneby, Sweden. E-mail: [email protected] Adeyinka Soneye Address: Polhemsgatan 27B, LGH 30, 371 40 Karlskrona, Sweden. E-mail: [email protected]
Optimization correlation for entropy production and energy availability in film condensation
No full textThis article investigates the physical significance of entropy production in plate film condensation. An irreversibility distribution ratio yields similar trends as previous studies, whereby the Prandtl number has suggested the relevant influence of inertial effects. Results for the optimized entropy production and plate size are expressed in terms of a duty parameter. It is observed that entropy production provides a useful parameter in the optimization of a two-phase system
Apparent entropy production difference with heat and fluid flow irreversibilities
No full textAn entropy-based procedure is presented to assess the solution accuracy in heat transfer problems with fluid flow using the second law of thermodynamics. The procedure is implemented by a control-volume-based finite-element formulation for discrete equations arising from the conservation laws and the second law. The study involves a comparison of the local entropy production rates computed from two forms of the discretized entropy equation. The computed local entropy production for two heat transfer problems, using the positive-definite and the transport forms of the entropy generation equation, agrees well with analytical solutions. It is demonstrated by the results of the numerical studies that there exists a relationship between a newly defined parameter, called the apparent error in entropy production, and the solution error in the computed value of the scalar in each control volume
Harnessing the Harmonious Sounds of Naija Music as Tool for Ethnic Integration in Nigeria
No full textNigeria, a nation of cultural diversity with several ethnic groups, has contended with challenges related to ethnic tensions and management strategies for national unity. In the continual search for measures of fostering national integration, this study looks at a different perspective on the role of contemporary Nigerian music, often called "Naija music," as a tool for fostering ethnic integration in the country. Relying on secondary sources such as articles, journals, texts, blogs and music data from streaming platforms, through content analysis, it observes that Naija music, characterised by its universal appeal, transcends geographical, linguistic, and cultural boundaries, making it a unifying force that brings Nigerians from various ethnic backgrounds together. This paper argues that the popularity of Naija music, characterised by artists with audiences across all states of the federation, can foster common bonds amongst the diverse entities within the country. This cross-cultural appreciation of Naija music demonstrates its potential as a unifying force in Nigeria. The findings of this research offer valuable insights into the use of music to foster national integration, enhance social cohesion, and promote unity among Nigerians, especially the youths who constitute a significant population
Modeling of entropy production in turbulent flows
No full textThis article presents new modeling of turbulence correlations in the entropy transport equation for viscous, incompressible flows. An explicit entropy equation of state is developed for gases with the ideal gas law, while entropy transport equations are derived for both gases and liquids. The formulation specifically considers incompressible forced convection problems without a buoyancy term in the y-momentum equation, as density variations are neglected. Reynolds averaging techniques are applied to the turbulence closure of fluctuating temperature and entropy fields. The problem of rigorously expressing the mean entropy production in terms of other mean flow quantities is addressed. The validity of the newly developed formulation is assessed using direct numerical simulation data and empirical relations for the friction factor. Also, the dissipation (ε) of turbulent kinetic energy is formulated in terms of the Second Law. In contrast to the conventional ε equation modeling, this article proposes an alternative method by utilizing both transport and positive definite forms of the entropy production equation
Cannabis use and risk of Clostridioides difficile infection: Analysis of 59,824 hospitalizations
No full textInternational audienceBackground: The prevalence of Clostridioides difficile Infection (CDI), the most notorious hospital acquired disease, and of excessive cannabis use (cannabis use disorder (CUD)) have both been steadily rising. Although cannabidiol, an active ingredient of cannabis, maintains gut integrity and suppresses entero-toxins from Clostridioides difficile, the relationship between CUD and CDI has not been studied.Methods: We selected adult records (age ≥ 18 years) from the Nationwide Inpatient Sample 2014, and identified CUD and other clinical conditions using ICD-9-CM codes. We used propensity scores derived from a multivariate logistic model to match CUD to non-CUD in a 1:1 ratio (29,912:29,912). We estimated the relative risk for CDI using log-binomial regression models with generalized estimating equations [SAS 9.4].Results: Among the matched hospitalizations (n = 59,824), cannabis usage was associated with a reduced prevalence of CDI (prevalence: 455.5 [95% CI: 385.1–538.8] vs. 636.4 [95% CI: 549.9–736.5] per 100,000 hospitalizations), resulting in a 28% reduced risk of CDI (relative risk: 0.72 [95% CI: 0.58–0.88]; p = 0002). Non-dependent and dependent CUD respectively had 23% and 80% reduced likelihood of CDI when compared to non-cannabis users (0.77 [95% CI: 0.60–0.95] and 0.20 [95% CI: 0.06–0.54]; p < 0.05). Furthermore, dependent users had less risk of CDI compared to non-dependent users (0.26 [95% CI: 0.08–0.88]; p = 0.01).Conclusions: CUD was associated with a decreased risk of CDI amongst hospitalized patients. Prospective and molecular mechanistic studies are required to elucidate how cannabis and its contents impacts CDI
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