Influence of the channel roughness factor change on the maximal design levels of a small watercourse in a given river cross (Nelma river example)

Сопротивление русла потоку, которое принято характеризовать коэффициентом шероховатости, значительно влияет на основные гидравлические характеристики водного объекта при оценке его пропускной способности. Любой малый водоток имеет свои особенности, так как достаточно быстро реагирует на изменения, происходящие на всей площади водосбора, поэтому требует отдельного исследования. В настоящей статье мы предприняли попытку рассчитать значение коэффициента шероховатости в половодье по данным наблюдений для р. Нельма. Установлено, что справочный коэффициент шероховатости дает завышенные значения максимального уровня воды. Расчеты показали, что с увеличением числа Фруда коэффициент шероховатости русла понижался. Полученные нами результаты могут быть использованы при разработке и уточнении методов определения основных расчетных гидрологических характеристик водотоков, устанавливаемых в целях безопасного использования прилегающих к ним территорий.

Theoretical Investigation of the Effects of some Geometrical Parameters on the Performance of Wire-Plate Electrostatic Precipitator

Some geometric parameters affecting the performance of a wire-plate electrostatic precipitator (ESP) are investigated theoretically. A numerical model was built to investigate the influence of the discharge wire size, wire separation, collector plates spacing, and roughness factor on the ESP performance. The results show that thinner wires emit higher current than larger ones at the same applied voltage, which would be suitable for low voltage power supply to generate the desired current density at the collecting electrodes. The results also show that, as the discharge electrodes get closer, the corona gets suppressed, resulting in a diminished corona current flow. On the other hand, as the distance between electrodes increases, the total current density decreases, leading to a less efficient ESP performance. Narrow spacing between collector plates gives a better performance. With regard to the effect of the roughness factor, the results revealed that the emitted current is strongly affected by the wires physical conditions.

Effect of Climate Changes and Coefficient of Surface Roughness on Soil Loss by Wind Erosion in Some Central and Southern Iraq

"act Woodruff and siddoway, 1965, established an equation for the estimation of soil Loss by wind erosion called Wind Erosion Equation (WEQ); solution of this equation gives the maximum amount of wind erosion under certain field conditions and is considered evidence in identifying the necessary methods for treating wind erosion in those conditions (Eltaif et al.,1991). This study aims to find out the extent to which climate change in the Samawah region of southern Iraq and Baghdad in central Iraq over a period of 34 years has affected values of soil losing by wind erosion using equation of (woodruff and siddoway, 1965) and effectiveness of this changes in soil surface roughness factor in reducing or increasing these loss. Two sites were selected located within central and southern regions of Iraq, one in Al-Jadiriya area in Baghdad governorate and the other in Samawah area in Al-Muthanna governorate. The results showed that estimated soil losing for years (1980-2013) in Al-Jadiriya decrease annually by 10-30 kg.hec.-1.year-1, while samawah increase by 240-760 kg.hec.-1.year-1. The effect of surface roughness factor was significant in reducing soil loss during period of study. Roughness factor for ridge (0.5) has reduced soil losing by 2.6 times compared to non-ridge soils (1).The ratio in semi-bridge soil (0.75) was 65%. This is due to the impact of bridge in reducing wind speed and reducing its erosivity. The general direction of soil loss indicates decrease in Al-Jadiriya area and increase in Samawah area with the case of fluctuation in soil loss between high and low of general direction line due to climate factor (C) in general equation of soil loss and it reflects ability of wind erosion, so decreased when wet conditions improved, by increased rainfall, reduced evaporation and increasing when dry conditions dominate Corresponding author: E-mail( [email protected] ) All rights reserved AlMuthanna University"

Effect of the Alloying Metal on the Corrosion Resistance of Pd-Rich Binary Alloys with Pt, Rh, and Ru in Sulfuric Acid

The paper presents the study of the corrosion resistance of electrodeposited Pd and its binary alloys with Pt, Rh, and Ru on a polycrystalline Au substrate. The corrosion resistance was tested in 0.5 M sulfuric acid at room temperature using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The morphology/composition and work function values were determined by scanning electron microscopy/energy–dispersive X–ray spectroscopy and scanning Kelvin probe, respectively. The obtained results revealed that the Pd electrode is the most resistant to corrosion, whereas the Pd-Ru electrode is the most susceptible to dissolution. It was found that the corrosion resistance of Pd-binary alloys decrease in the following order: Pd > Pd-Pt > Pd-Rh > Pd-Ru. This effect was assigned mainly to the difference in surface roughness factor of tested electrodes.

ROUGHNESS FACTOR FOR MULTI-LAYER ARMOUR AS OVERTOPPING ESTIMATOR

Nowadays one of the most challenging problem for engineers is to adapt existing coastal structures to climate changes. Wave overtopping is highly sensitive to the increasing extreme water depths due to higher storm surges coupled with sea level rise. One way to face these problems for rubble mound breakwaters is to add one or more layers to the existing armour. Prediction of wave overtopping of coastal structures is presently obtained from empirical formulae in EurOtop (2018). For the case of overtopping over multi-layer armour, no validated method exists, so prediction must be based upon assumptions and judgement, with related uncertainties. This study is focused on the effects of different types of armour, the number of layer and other structural characteristics on the roughness factor f. The main effects of porosity and roughness will be investigated. This paper analyzes the results of several new physical model tests of different rubble mound breakwaters reproduced at the new medium scale random wave flume of the Department of Engineering of Roma Tre University.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/8cOdqkqQ-9s

Polyaniline coating electrochemical properties improvement after roughened platinum substrate and its anti-wear performance study

In order to improve the electrochemical performance of the neural electrode the polyaniline coatings were modified on roughened Pt (PANI/rPt1) electrodes using electrochemical method. The roughness factor (fR up to 424) of Pt surfaces increased significantly through electrochemical roughening processing. PANI/rPt electrodes showed excellent interfacial properties. Specifically, about 5.6-fold increase in the charge density of PANI/rPt (fR = 424) was observed, while the interfacial impedance (103.5 Ω) was reduced by 50% compared to that of PANI coatings on the smooth Pt surfaces (PANI/sPt2). The results indicate the potential application of PANI/rPt as an efficient and stable future neural interface. In addition, the wear test shows that the coating did not fail during the wearing period and holds an excellent wear resistance ability.

Controlling wetting properties on nanostructure surfaces by the coupled effect of the structural parameter and roughness factor

Aims: The wetting properties of the nanostructure surface can be controlled by the structural parameter associate with roughness surface. Background: Increasing the roughness of hydrophobic surface can enhance the hydrophobicity of the surface. Objective: We chose copper material modified by fluorosilane as the substrate, and used Lammps software to establish four different shapes nanostructures, square pillar, cylinder, frustum and cone nanostructure respectively with pillar height and theoretical gap changing to study the influence of structural parameter and roughness factor on wetting properties of surfaces. Method: Molercular dynamic simulation Result: The structural parameter h/b can determine the wetting transition of the droplet on surfaces. With the same height and theoretical gap, the contact angle of the frustum and the cone surfaces is larger than that of the square pillar surfaces and cylinder surfaces due to the effect of wedge surface. Conclusion: (1)The values of the contact angle exhibit a strong dependence on roughness factor. The roughness factor will increase by this way of increasing height and decreasing gap, and the contact angle of droplet increase with the roughness factor increasing on the four surfaces. There exists the critical structural parameter h/b to determine the Cassie and Wenzel state transition of the droplet on various nanostructure surfaces.And the critical structural parameter values are 1.5, 1.5, 2.08 and 2.24 for the square pillar, cylinder, frustum and cone nanostructures respectively. Other: The wetting properties can be controlled by the structural parameter associate with the roughness factor. Increasing the pillar height and decreasing the gap of the nanostructure surfaces will make the structural parameters reach the standard of transition value h/b of the droplet state, and the droplet will change from Wenzel state to Cassie state.

Accuracy Assessment of Aster and Srtm Data W.R.T Lidar Data for Jeddah City- Ksa

Most of Civil Engineering projects and Earthworks need a Digital Elevation Models (DEM), such as: infrastructure, utilities, flood hazard determination, road design, and watershed management. Furthermore, Digital Elevation Models are very important for geodetic applications and the knowledge of the earth's surface topography as well as the field of Earth sciences. In the current research work, a comparative study will be done to evaluate the accuracy come out from two available sources of DEMs. Also, this research will assess their suitability in engineering applications in the Jeddah city (KSA). Two Global DEM (GDEM) have been focused, the first one is the ASTER and the second one is SRTM3 with respect to LIDAR Data for the same regions. The current study will concentrate on the accuracy assessment of SRTM and ASTER Data in Jeddah, KSA. The obtained result from this current research (study areas of North East, Medal East and South East) of Jeddah city for ASTER data has an accuracy inversely proportional with the roughness factor. Also, the accuracy of SRTM is an inversely proportional with the roughness factor. In this context, in flat terrain the accuracy is between about 1 m to about 2.5m, and about 5m to10 m for rolling terrain. However, it's about 20m to 30 m for mountainous terrain for ASTER data. On other words, the accuracy of SRTM on flat terrain is between about 0.5 m to less than 1.8 m, and about 6.5m to10. 5 m for rolling terrain. However, it's about 23m to 30 m for mountainous terrain. Finally, the research work is obtained that, in flat terrain, the accuracy of SRTM data is less than the accuracy of ASTER data. But the comparative accuracy between them is approximately the same for rolling terrain. However, for mountainous terrain the accuracy of ASTER data is almost better than the accuracy of SRTM data