This study presents the results of an experimental investigation focusing on the effects of the inflow boundary layer on the wake characteristics of a 0.12 m diameter porous disk with radially non-uniform porosity in terms of mean flow, turbulence, and wake scaling. Two-dimensional two-component particle image velocimetry measurements within the wake are performed up to 7.5 diameters downstream as the disk is lowered deeper into a boundary layer that is representative of a neutral atmospheric boundary layer over a flat terrain. Results show that otherwise symmetrical wake velocity profiles that exist outside the boundary layer get skewed and sheared around the disk centerline in the boundary layer due to the inflow wind shear. The turbulent kinetic energy, its production, and Reynolds shear stress levels in the wake get asymmetrical around the centerline of the disk such that the production of turbulent kinetic energy is observed to be higher above centerline. Due to the inflow shear, the wake centerline gets shifted downwards (i.e., toward the wind tunnel wall), which is in contrast to the observations on real wind turbine wakes in the literature where the wake actually lifts up. The asymmetrical and skewed velocity profiles both in the streamwise and cross-stream directions can be collapsed onto a single function by using proper wake scaling parameters based on the ratio of local strain to average strain within the velocity profile calculated separately for either side of the wake.

Background: HCV and DM are chronic diseases of high global prevalence. Many studies proved the association between Hepatitis C and DM in the last three decades and this consists of an interrelated association; moreover, HCV infection triggers Diabetes Mellitus, most probably type 2. Objective: To assess the possibility of the improvement of T2DM in patients with HCV when applying the new DAA HCV treatment in Egypt. Patients and Methods:The current study is a prospective cohort hospital-based study that aims to describe the association between T2DM on one hand and chronic HCV on the other hand after successful management of HCV through the DAAs according to the protocol of the Ministry of Health. SVR was defined as undetectable HCV RNA levels at 12 weeks after the end of treatment (EOT). Fasting plasma glucose (FPG) levels between 100-125 mg/dL were defined as prediabetes and FPG ≥ 126 mg/dL was defined as diabetes. We have found positive correlation between management of HCV using DAAs in general and improvement of HbA1c and FPG. Moreover, we reported stronger correlation between achieving SVR and the HbA1c level and FPG. Results: After 12 weeks of follow-up, 82% of the patients maintained negative SVR, hemoglobin reduction was -0.6±0.4 %, 3 months after HCV treatment with a P value <0.001*. FPG reduction was -24.6±25.4 after 3 months of treatment with a P value of <0.001*. HbA1c reduction in patients with SVR was -0.8±0.2 % with a P value of <0.001*. No significant change in treatment choice was found during the period of study. Conclusion: Successful HCV eradication will result in a statistically significant reduction in fasting plasma glucose and HbA1c in patients with type 2 diabetes which is an indirect indicator of improvement of insulin sensitivity in patients with type 2 DM.

No abstract

This study presents the results of an experimental investigation that focuses on quantifying the differences between the spreading rates of a model wind turbine wake and a porous disc wake at different freestream turbulence intensity levels. Two-dimensional two-component particle image velocimetry (2D2C PIV) measurements are performed within the wakes of a model wind turbine and a porous disc (up to 7D downstream) of the same diameter and a matching thrust coefficient. The wind turbine is operated at a Tip Speed Ratio (TSR) of 2 in order to have matching thrust coefficient conditions for a consistent wake comparison. The results show that the mean wake flow field (both near and far wake) is significantly different for the wind turbine compared to the porous disc even if they are operating at similar, high or low, freestream turbulence levels. The wake of the wind turbine recovers much faster than that of a porous disc with a matching thrust coefficient especially in the far wake region at both low and high freestream turbulence levels. On the other hand, the data shows that the far wake of the turbine operating at low freestream turbulence is very similar to that of the disc operating at high freestream turbulence. This suggests caution and stresses the importance in choosing the freestream turbulence intensity level when using porous discs to represent wind turbines in wind tunnel studies.

The effects of freestream turbulence intensity on the wake development of a model wind turbine and a porous disc are investigated through Proper Orthogonal Decomposition (POD) analysis. The capability of porous discs for reproducing far-wake characteristics of a model wind turbine is examined through coherent structures both in the near-wake and far-wake regions. Instantaneous velocity fields are obtained through wake measurements using two-dimensional two-component particle image velocimetry (2D2C PIV). These velocity fields are considered snapshots of the spatial domain. Results show inherent differences between coherent structures of a model wind turbine and porous disc in the near-wake region, especially when the freestream turbulent intensity level is low. However, these differences reduce, and coherent structures become more comparable when the freestream turbulence intensity level is higher. It is shown that the first five streamwise components of POD modes are paired for the model wind turbine and the porous disc cases under high freestream turbulence intensity conditions in the far-wake region.