Optimal two-dimensional roughness for transition delay in high-speed boundary layer

The influence of surface roughness on transition to turbulence in a Mach 4.5 boundary layer is studied using direct numerical simulations. Transition is initiated by the nonlinearly most dangerous inflow disturbance, which causes the earliest possible breakdown on a flat plate for the prescribed inflow energy and Mach number. This disturbance is primarily comprised of two normal second-mode instability waves and an oblique first mode. When localized roughness is introduced, its shape and location relative to the synchronization points of the inflow waves are confirmed to have a clear impact on the amplification of the second-mode instabilities. The change in modal amplification coincides with the change in the height of the near-wall region where the instability wave-speed is supersonic relative to the mean flow; the net effect of a protruding roughness is destabilizing when placed upstream of the synchronization point and stabilizing when placed downstream. Assessment of the effect of the roughness location is followed by an optimization of the roughness height, abruptness and width with the objective of achieving maximum transition delay. The optimization is performed using an ensemble-variational (EnVar) approach, while the location of the roughness is fixed upstream of the synchronization points of the two second-mode waves. The optimal roughness disrupts the phase of the near-wall pressure waves, suppresses the amplification of the primary instability waves, and mitigates the nonlinear interactions that lead to breakdown to turbulence. The outcome is a sustained non-turbulent flow throughout the computational domain

Investigation of mass transfer, thermodynamics, and greenhouse gases properties in pennyroyal drying

In this research, kinetic analysis, energy, exergy, and greenhouse gases of a hybrid laboratory dryer (solar-hot air) are presented for pennyroyal. Drying was performed at input temperatures of 50, 60, and 70°C and air velocities of 0.6, 1.2, and 1.8 m/s. The effect of drying variables on moisture ratio, effective moisture diffusivity, specific energy consumption, energy utilization ratio, energy utilization, exergy efficiency, and exergy loss was investigated. The highest amounts of effective moisture diffusivity and specific energy consumption were 2.30 × 10−10 m2/s and 48.60 kWh/kg, respectively. Energy utilization and energy utilization ratio varied from 0.0064 to 0.0826 kJ/s and from 0.056 to 0.957, respectively. Exergy loss and exergy efficiency varied between 0.0037 to 0.0510 kJ/s and 0.2428 to 0.8731, respectively. In addition, by increasing the temperature and intake air velocity, drying rate increased and the emissions of greenhouse gases (CO2, SO2, and NOX) were reduced. Practical Applications: Modeling of the drying process is an important aspect of drying technology, especially in drying for industrial purposes. The aim of modeling is to select the most suitable drying method and the best operating conditions for obtaining the product. Some of the key issues in drying have been to reduce the price of the energy resources used, increase the drying efficiency, and improve the quality of the dried products. The concept of exergy is defined by the concept of reversible work. The concept of reversibility depends on energy balance and mass regardless of energy quality (exergy loss).</p

Elderberry diet improves memory function and prevents cell death in rat models of Alzheimer’s disease induced by amyloid beta injection

Background: Alzheimer’s disease (AD) is a neurodegenerative disease which adversely affects memory and learning skills. Currently, there is no disease-modifying therapeutic approach for AD. Aim: A growing body of literature suggests elderberry as a promising remedy for neurological disorders. This study investigates the therapeutic effects of the elderberry diet on amyloid beta-induced (Aβ) rat model. Methods:&nbsp; Initially, Alzheimer’s model was generated by Aβ administration followed by the treatment of elderberry diet. Then, short term spatial memory was assessed. Stereology was also performed for the evaluation of density of neurons and dark neuron in the hippocampus. Results: The findings showed that the administration of the elderberry diet in an Aβ model of Alzheimer’ disease improved memory and learning function and prevented the degeneration of hippocampal neurons. Conclusion: Overall, the findings imply that the elderberry diet attenuates the Aβ-induced degeneration and improves memory performance. As such, the elderberry diet could be used as a therapeutic procedure for Alzheimer due to its neuroprotective effects

Nanoclay Performance on Resistance of Clay under Freezing Cycles

This study aims to investigate effect of nanoclay on resistance of the exposed clay soils in freezing in vitro conditions. The clay sample was selected from the considered land. Then they were mixed on water in 1.5, 3, 4.5 and 6 percents as well as without nanoclay. There were prepared cylinders with 3.81 cm diameter and 7.62 cm height, which they have been placed in conditions without freezing, one cycle, two cycles and three cycles of freezing. Then they were tested under uniaxial experiment. Then they were analyzed by SPSS software. The results show that adding nanoclay with 1.5, 3, 4.5 and 6 percents will reduce soil strength during freezing cycles. It can be occurred because adding nanoclay will result to increase special surface of the samples; consequently, increasing electrical load increases water absorption, which it can be partly cause of non-effective increasing nanoclay in soil resistance. There is also a significant difference between pressure strength of soils with lower humidity and those with higher humidity. It confirms that increasing humidity decreases strength level, which increasing water absorption of samples by nanoclay is reason of decreasing strength. There is an inverse significant relationship between increasing nano and soil water absorption, which its reason may be that adding nanoclay because of increasing samples special surface and consequently, increasing electricity load will increase water absorption and samples’ plasticity. It can be expected that samples’ permeability will decline by increasing their plasticity. There is also a significant relationship between increasing nano and soil liquid and doughiness limit that its reason can be increasing rate of water absorption in samples due to presence of nanoclay.© JASEMKeywords: Nanoclay, Resistance, Freezing, Sample, Uniaxia

Waste management using an automatic sorting system for carrot fruit based on image processing technique and improved deep neural networks

In this study, we address the problem of classification of carrot fruit in order to manage and control their waste using improved deep neural networks. In this work, we perform a deep study of the problem of carrot classification and show that convolutional neural networks are a straightforward approach to solve the problem. Additionally, we improve the convolutional neural network (CNN) based on learning a pooling function by combining average pooling and max pooling. We experimentally show that the merging operation used increases the accuracy of the carrot classification compared to other merging methods. For this purpose, images of 878 carrot samples in various shapes (regular and irregular) were taken and after the preprocessing operation, they were classified by the improved deep CNN. To compare this method with the other methods, image features were extracted using Histograms of Oriented Gradients (HOG) and Local Binary Pattern (LBP) methods and they were classified by Multi-Layer Perceptron (MLP), Gradient Boosting Tree (GBT), and K-Nearest Neighbors (KNN) algorithms. Finally, the method proposed based on the improved CNN algorithm, was compared with other classification algorithms. The results showed 99.43% of accuracy for grading carrot through the CNN by configuring the proposed Batch Normalization (BN)-CNN method based on mixed pooling. Therefore, CNN can be effective in increasing marketability, controlling waste and improving traditional methods used for grading carrot fruit

The driver responses to the vibration of tractor

Whole body vibration is one of the main causes of musculoskeletal disorders of drivers. The purpose of this study was to investigate the allowable exposer time, the care limit and driver response to the vibrations of the seat of ITM 475 Tractor. A three-way accelerometer was used to carry out the tests in the present study based on the ISO 2631-1 international vibration standard. The studied factors were engine rotational speed at three levels of 1000, 1500 and 2000 rpms, gear ratio (1, 2 and 3) and road at two level, dirt and asphalt. The obtained data were analyzed through factorial experiment based on completely randomized design with 18 treatments and three replications. The results showed that effects of the main factors and those of their interactions on the total vibration emitted from the tractor seat were significant at 1% probability level. The highest amount of whole body vibration on a dirt road was 1.49 m s-2 which took placed at 2000 rpm and the 3rd gear ratio. Consequently, the minimum exposure time and the driver care time limit were 1.16 and 0.14 h, respectively. This treatment was in very uncomfortable range. The maximum whole body vibration for 8 h ride on ITM 475 was 0.85 m s-2. Therefore, it is necessary to reduce whole body vibration of the studied tractor via designing a cabin and/or a new seat

Endoscopic repair of transsellar transsphenoidal meningoencephalocele; Case report and review of approaches

We present an extremely rare case of transsellar transsphenoidal meningoencephalocele in a 36-year-old woman with pituitary dwarfism complaining of nasal obstruction. Imaging studies showed a bony defect in the sellar floor and sphenoid sinus with huge nasopharyngeal mass and 3rd ventricle involvement. Using endoscopic endonasal approach the sac was partially removed and the defect was reconstructed with fat and fascial graft, and buttressed with titanium mesh and septal flap. Visual field improvement was noticed post-operatively and no complication was encountered during follow-up. So, endoscopic endonasal approach with partial resection of the sac is a safe and effective treatment for this disease. © 2015 The Authors. Published by Elsevier B.V

Probabilistic modeling of crop-yield loss risk under drought: A spatial showcase for sub-Saharan Africa

Assessing the risk of yield loss in African drought-affected regions is key to identify feasible solutions for stable crop production. Recent studies have demonstrated that Copula-based probabilistic methods are well suited for such assessment owing to reasonably inferring important properties in terms of exceedance probability and joint dependence of different characterization. However, insufficient attention has been given to quantifying the probability of yield loss and determining the contribution of climatic factors. This study applies the Copula theory to describe the dependence between drought and crop yield anomalies for rainfed maize, millet, and sorghum crops in sub-Saharan Africa (SSA). The environmental policy integrated climate model, calibrated with Food and Agriculture Organization country-level yield data, was used to simulate yields across SSA (1980-2012). The results showed that the severity of yield loss due to drought had a higher magnitude than the severity of drought itself. Sensitivity analysis to identify factors contributing to drought and high-temperature stresses for all crops showed that the amount of precipitation during vegetation and grain filling was the main driver of crop yield loss, and the effect of temperature was stronger for sorghum than for maize and millet. The results demonstrate the added value of probabilistic methods for drought-impact assessment. For future studies, we recommend looking into factors influencing drought and high-temperature stresses as individual/concurrent climatic extremes. © 2022 The Author(s). Published by IOP Publishing Ltd

A green and efficient method for the preparation of 3, 4- dihydropyrimidin-2(1H)-ones using quaternary ammonium- treated clay in water

Abstract: In this study, a variety of 3, 4-dihydropyrimidin-2(1H)-ones derivatives were synthesized via three-component Biginelli reaction. The quaternary ammonium-treated clay -catalyzed process proved to be simple, efficient, and environmentally friendly