Modeling Of Atmospheric Refraction Effects On Traffic Noise Propagation

Traffic noise has been shown to have negative effects on exposed persons in the communities along highways. Noise from transportation systems is considered a nuisance in the U.S. and the government agencies require a determination of noise impacts for federally funded projects. There are several models available for assessing noise levels impacts. These models vary from simple charts to computer design models. Some computer models, i.e. Standard Method In Noise Analysis (STAMINA), the Traffic Noise Model (TNM) and the UCF Community Noise Model (CNM), have been used to predict geometric spreading, atmospheric absorption, diffraction, and ground impedance. However, they have largely neglected the atmospheric effects on noise propagation in their algorithms. The purpose of this research was to better understand and predict the meteorological effects on traffic noise propagation though measurements and comparison to acoustic theory. It should be noted that this represents an approach to incorporate refraction algorithms affecting outdoor noise propagation that must also work with algorithms for geometric spreading, ground effects, diffraction, and turbulence. The new empirical model for predicting atmospheric refraction shows that wind direction is a significant parameter and should be included in future modeling for atmospheric refraction. To accomplish this, the model includes a wind shear and lapse rate terms instead of wind speed and temperature as previously needed for input of the most used models. The model is an attempt to explain atmospheric refraction by including the parameters of wind direction, wind shear, and lapse rate that directly affect atmospheric refraction

Biotechnological applications of polymeric nanofiber platforms loaded with diverse bioactive materials

This review article highlights the critical research and formative works relating to nanofiber composites loaded with bioactive materials for diverse applications, and discusses the recent research on the use of electrospun nanofiber incorporating bioactive compounds such as essential oils, herbal bioactive components, plant extracts, and metallic nanoparticles. Inevitably, with the common advantages of bioactive components and polymer nanofibers, electrospun nanofibers containing bioactive components have attracted intense interests for their applications in biomedicine and cancer treatment. Many studies have only concentrated on the production and performance of electrospun nanofiber loaded with bioactive components; in this regard, the features of different types of electrospun nanofiber incorporating a wide variety of bioactive compounds and their developing trends are summarized and assessed in the present article, as is the feasible use of nanofiber technology to produce products on an industrial scale in different applications

The Importance of Imaging Assessment Before Endovascular Repair of Thoracic Aorta

AbstractIndications for and experience with placement of endovascular stent grafts in the thoracic aorta are still evolving. Recent advances in imaging technologies have drastically boosted the role of pre-procedural imaging. The accepted diagnostic gold standard, digital subtraction angiography, is now being challenged by the state-of-the-art computed tomography angiography (CTA), magnetic resonance angiography (MRA) and trans-oesophageal echocardiography (TEE). Among these, technological advancements of multidetector computed tomography (MDCT) have propelled it to being the default modality used, optimising the balance between spatial and temporal resolutions and invasiveness. MDCT angiography allows the comprehensive evaluation of thoracic lesions in terms of morphological features and extent, presence of thrombus, relationship with adjacent structures and branches as well as signs of impending or acute rupture, and is routinely used in these settings.In this article, we review the current state-of-the-art radiological imaging for thoracic endovascular aneurysm repair (TEVAR), especially focusing on the role of MDCT angiography. After analysing the technical aspects for optimised imaging protocols for thoracic aortic diseases, we discuss pre-procedural determinants of candidacy, and how to formulate interventional plans based on cross-sectional imaging

Isolation and screening of some medically important fungi from indoor environment: Studying the effect of some environmental and chemical factors on their growth and spore adhesion

Isolation of some pathogenic fungi from indoor environment that may cause diseases to athletes was the goal of this work. The effect of different cloth materials and some environmental factors on the growth and adhesion of the isolated fungi as Aspergillus sydowii, Cochliobolus hawaiiensis, Cochliobolus lunatus, Epicoccum nigrum, Nigrospora oryzae, Penicillium aurantiogriseum, Cladosporium sphaerospermum, Aspergillus niger, Cochliobolus australiensis, Stemphylium botryosum, Alternaria. alternata, Fusarium chlamydosporum, Aspergillus flavus and Aspergillus versicolor was investigated. By studying the effect of different cloth materials, at temperatures (18, 25 and 35°C) and at pH values (4, 5.6, 8), it was concluded that cloth material, 74% cotton - 25% polyester- 1% elasthan (C.P.E) was the lowest in susceptibility to fungal attack. The fungal pathogens growth was favored at 35°C and pH 8 after two days of incubation while, after five days the growth was favored at 25 and 35°C at pH 5.6 and pH 8. Alter. alternata and A. flavus were selected for studying their spore adhesion on different cloth material samples. Also, their sensitivity for detergents and drugs on different cloth material samples was carried out.Key words: Pathogenic fungi, athletes, fungal adhesion, antimicrobial activity

Fracture simulation of viscoelastic membranes by ordinary state-based peridynamics

Despite a load below the elastic limit is applied on a viscoelastic material, the material may fail after a long duration of constant loading because of the time-dependent viscous deformations. ln this regard, a viscoelastic material model in the ordinary statebased peridynamic framework is proposed to capture crack propagation in polymeric water treatment membranes. The defom1at ion state is decoupled into dilatational and distortional parts, and it is assumed that the dilatational part of defom1ation is elastic, while the distortional pru1 is considered as viscoelastic, whose behaviour can be represented by the Prony series. First, we verify our implementation with FEM results for a benchmark case. Afterwards, the crack propagation is studied by the viscoelastic ordinary state-based peridynamic model

Mechanical analyses of flat sheet water treatment membranes

In this work, we address the mechanical response of the flat sheet polymeric water treatment membranes under the assumed operational loading conditions. Firstly, we perform quasi-static analyses of the membranes under normal pressure loads, which is the condition that resembles the actual loading for flat sheet membranes in the submerged membrane bioreactors. Then, the long-term deformation of the membranes is studied under the assumed filtration durations for the same loading conditions by utilizing the viscoelastic material models. The quasi-static and viscoelastic membrane simulations are performed by a commercial finite element code ANSYS. Finally, the mechanical fatigue life predictions are carried out based on the stress distributions from the quasi-static analyses and the long-term effects from the viscoelastic analyses

Modelling of Eulerian incompressible fluid flows by using peridynamic differential operator

This study presents a novel method for modelling of Eulerian incompressible fluid flow by using peridynamic differential operator. The peridynamic differential operator is used to calculate partial derivatives in the Navier-Stokes equations. The pressure Poisson equation is used to obtain the pressure field whereas the velocity field is obtained by solving momentum equations. The numerical procedure to solve Navier-Stokes equations in peridynamics for the incompressible fluid is also provided. The capability of the proposed peridynamic incompressible fluid model is demonstrated by considering problems of two-dimensional cavitation, a flow inside an open channel, and a flow over a cylinder. Moreover, to demonstrate the capabilities of the proposed model, the problems of two-dimensional cavitation and a flow over a cylinder are investigated for different Reynolds numbers. The vortex shedding is also captured for the problem of a flow over a cylinder at Reynolds number of 푅푒 = 100. For verification purposes, the peridynamic results are compared with the results obtained by ANSYS Fluent, a commercial fluid dynamics software

Fatigue crack prediction in ceramic material and its porous media by using peridynamics

Peridynamics is a nonlocal reformulation of the classical continuum mechanics using integro-differential equations. Since the integro-differential equations used in peridynamics are valid in both continuous and discontinuous models, the theory is suitable for predicting progressive damages. In this study, fatigue crack growth in a ceramic material and its porous media is predicted by using the peridynamic model for fatigue cracking. First, the fatigue crack propagation in compact specimen of a non-porous ceramic material is considered. The predicted fatigue crack growth rate is compared with experimental results. Next, the fatigue crack growths in ceramic material with different porosity levels are investigated. The fatigue crack growth rate of porous materials is compared with the non-porous material to analyse the effects of porosity on fatigue crack growth. A linear relation between the relative change of fatigue crack growth rate, stress intensity factor range and porosity level is obtained by using linear regression analysis

Evaluation of dynamic behaviour of porous media including micro-cracks by ordinary state-based peridynamics

Reliable evaluation of mechanical response in a porous solid might be challenging without any simplified assumptions. Peridynamics (PD) perform very well on a medium including pores owing to its definition, which is valid for entire domain regardless of any existed discontinuities. Accordingly, porosity is defined by randomly removing the PD interactions between the material points. As wave propagation in a solid body can be regarded as an indication of the material properties, wave propagation in porous media under an impact loading is studied first and average wave speeds are compared with the available reference results. A good agreement between the present and the reference results is achieved. Then, micro-cracks are introduced into porous media to investigate their influence on the elastic wave propagation. The micro-cracks are considered in both random and regular patterns by varying the number of cracks and their orientation. As the porosity ratio increases, it is observed that wave propagation speed drops considerably as expected. As for the cases with micro-cracks, the average wave speeds are not influenced significantly in random micro-crack configurations, while regular micro-cracks play a noticeable role in absorbing wave propagation depending on their orientation as well as the number of crack arrays in y-direction

Ischaemic strokes in patients with pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia: associations with iron deficiency and platelets.

<div><p>Background</p><p>Pulmonary first pass filtration of particles marginally exceeding ∼7 µm (the size of a red blood cell) is used routinely in diagnostics, and allows cellular aggregates forming or entering the circulation in the preceding cardiac cycle to lodge safely in pulmonary capillaries/arterioles. Pulmonary arteriovenous malformations compromise capillary bed filtration, and are commonly associated with ischaemic stroke. Cohorts with CT-scan evident malformations associated with the highest contrast echocardiographic shunt grades are known to be at higher stroke risk. Our goal was to identify within this broad grouping, which patients were at higher risk of stroke.</p><p>Methodology</p><p>497 consecutive patients with CT-proven pulmonary arteriovenous malformations due to hereditary haemorrhagic telangiectasia were studied. Relationships with radiologically-confirmed clinical ischaemic stroke were examined using logistic regression, receiver operating characteristic analyses, and platelet studies.</p><p>Principal Findings</p><p>Sixty-one individuals (12.3%) had acute, non-iatrogenic ischaemic clinical strokes at a median age of 52 (IQR 41–63) years. In crude and age-adjusted logistic regression, stroke risk was associated not with venous thromboemboli or conventional neurovascular risk factors, but with low serum iron (adjusted odds ratio 0.96 [95% confidence intervals 0.92, 1.00]), and more weakly with low oxygen saturations reflecting a larger right-to-left shunt (adjusted OR 0.96 [0.92, 1.01]). For the same pulmonary arteriovenous malformations, the stroke risk would approximately double with serum iron 6 µmol/L compared to mid-normal range (7–27 µmol/L). Platelet studies confirmed overlooked data that iron deficiency is associated with exuberant platelet aggregation to serotonin (5HT), correcting following iron treatment. By MANOVA, adjusting for participant and 5HT, iron or ferritin explained 14% of the variance in log-transformed aggregation-rate (p = 0.039/p = 0.021).</p><p>Significance</p><p>These data suggest that patients with compromised pulmonary capillary filtration due to pulmonary arteriovenous malformations are at increased risk of ischaemic stroke if they are iron deficient, and that mechanisms are likely to include enhanced aggregation of circulating platelets.</p></div