Mechanism of saline deposition and surface flashover on high-voltage insulators near shoreline:mathematical models and experimental validations

This paper deals with sea salt transportation and deposition mechanisms and discusses the serious issue of degradation of outdoor insulators resulting from various environmental stresses and severe saline contaminant accumulation near the shoreline. The deterioration rate of outdoor insulators near the shoreline depends on the concentration of saline in the atmosphere, the influence of wind speed on the production of saline water droplets, moisture diffusion and saline penetration on the insulator surface. This paper consists of three parts: first a model of saline transportation and deposition, as well as saline penetration and moisture diffusion on outdoor insulators, is presented; second, dry-band initiation and formation modelling and characterization under various types of contamination distribution are proposed; finally, modelling of dry-band arcing validated by experimental investigation was carried out. The tests were performed on a rectangular surface of silicone rubber specimens (12 cm × 4 cm × 8 cm). The visualization of the dry-band formation and arcing was performed by an infrared camera. The experimental results show that the surface strength and arc length mainly depend upon the leakage distance and contamination distribution. Therefore, the model can be used to investigate insulator flashover near coastal areas and for mitigating saline flashover incidents.</p

The Organisation of African Unity and the promotion and protection of human rights in Africa

The adoption of the African Charter on Human and Peoples Rights (AFCHPR) on 17 June 1981 by the O. A. U. Assembly of Heads of States and Government is, singly, the most significant act in the field of Human Rights protection in Africa. The Charter entered into force on 21 October 1986. These developments have inspired the Commission of this thesis.The aim of this thesis is to examine the promotion and protection of human rights in Africa in three main areas, namely, historical/cultural perspectives, national and regional legal regimes for the promotion and protection of human rights in Africa

Effect of pH and exchangeable metals on phosphate adsorption by soils

A rapid and precise method for determination of surface charge density of soils was developed. The method involves saturating the negative and positive exchange sites with NH[subscript]4[superscript]+ and NO[subscript]3[superscript]-, respectively, removing the excess solution, and determining the ions on the exchange sites by steam distillation.;Studies on the effect of pH and exchangeable cations on P adsorption by six slightly acid, Iowa surface soils showed that the minimum adsorption occurred at a narrow pH range (ca. zpc, 4.5 to 5.5), below and above which phosphate adsorption increased sharply. The increase in P adsorption below this minimum adsorption was attributed to the effect of Al and Fe oxides, and the P adsorption above this pH range was attributed to the effect of exchangeable cations. This was confirmed by saturating the exchange sites with NH[subscript]4[superscript]+.;Adsorption of P by NH[subscript]4-saturated soils was less than that by untreated or water-leached soils when water was used as a matrix solution, and it was the greatest when 0.01 M CaCl[subscript]2 was the matrix solution. The amounts of NH[subscript]4[superscript]+ released to 0.01 M CaCl[subscript]2 confirmed the importance of exchangeable Ca in P adsorption. The amounts of P adsorbed by alkali metal-saturated soils decreased in the order of the following metals: K ≥ Na \u3e Rb \u3e Cs \u3e Li \u3e untreated soils when 0.01 M CaCl[subscript]2 was the matrix solution. The amounts of P adsorbed by alkaline earth metal-saturated soils were greater than those adsorbed by alkali metal-saturated soils. Regardless of the matrix solution used, the amounts of P adsorbed by the alkaline earth metal-saturated soils decreased in the order of the following metals: Ba \u3e Ca \u3e Mg \u3e Sr \u3e untreated soil. Saturation of soils with selected heavy metals increased P adsorption, and these increases were greater than those obtained for alkali metal- and alkaline earth metal-saturated soils. The amounts of P adsorbed were affected by the saturating heavy metal, with the following decreasing order: Pb \u3e Cu \u3e Zn \u3e Ni \u3e Cd \u3e Mn. Precipitation reactions were considered, but they were rejected for alkali metal- and alkaline earth metal-saturated soils, but they were possible for Cu-, Zn-, or Pb-saturated soils. Application of the Langmuir model showed that the adsorption maximum (X[subscript] m) and the affinity coefficient (k) are affected by the type of exchangeable metal and the matrix solution used

The Organisation of African Unity and the promotion and protection of human rights in Africa

The adoption of the African Charter on Human and Peoples Rights (AFCHPR) on 17 June 1981 by the O. A. U. Assembly of Heads of States and Government is, singly, the most significant act in the field of Human Rights protection in Africa. The Charter entered into force on 21 October 1986. These developments have inspired the Commission of this thesis.The aim of this thesis is to examine the promotion and protection of human rights in Africa in three main areas, namely, historical/cultural perspectives, national and regional legal regimes for the promotion and protection of human rights in Africa

Effects of irrigation water salinity on forage growth and qualities of some salt tolerant species under UAE conditions

Experiments were conducted at the International Center for Bio saline Agriculture (ICBA) in Dubai to evaluate the growth and productivity of some locally grown grass species; Rhodes grass (Chloris gayana L.) var. Katambora, Pioneer, and Callide; and Panicum grass (Panicum maximum) var. Green, and Gatton over a range of irrigation levels (1 gal/hr and 1.3 gal/hr), and water salinity (5 dS/m, 10 dS/m and 15 dS/m). The effect of different quality of water in respect to the salinity levels would provide information about water use efficiencies and soil salinity over a period. Growth and biomass productivity of the test species were periodically monitored and measured for every harvest (plant height, total tiller no., leaf length, internodes length, total fresh weight per m2, total dry weight per m2, leaf dry weight per m2, leaf area per m2, stem dry weight per m2, leaves fresh weight per m2, stem fresh weight per m2, leaf area per m2, and fertile tillers no. per m2). Forage quality of these species were evaluated to determine organic (protein, ADF (acid detergent fiber) and NDF (neutral detergent fiber), dry matter, and ash) and inorganic contents (Ca, K, Na, Cl and Mg) of the harvested materials. In order to assess the effects of salinity irrigation water on salt accumulation, soil samples were collected at different depths of the soil (30 cm and 60 cm) from various sampling spots of the trial and analyzed for salt content, and correlated with forage productivity and quality. Results showed that some of the plant measurements were not affected by salinity, although it has shown resistance to salinity. For example, at cut no. 2, at irrigation 1.3 gal/hr, Rhodes grass (Callide) has a fresh weight of 1421 g per m2, 1205 g, 1086 g, at salinity levels 5, 10, 15 dS/m respectively. The above results showed that the plant was significantly affected by salinity (P\u3e0.05) and slightly decreased its fresh weight while the salinity increased three times. In conclusion, plant was significantly affected by salinity, and in the meantime, it has produced a proper fresh weight. There was a significant difference between cuts, cultivars within the same cut or other cuts, according to interaction with the environment, or the implemented salinity or irrigation level

Understanding and Controlling Magnetic Damping Behaviour in Synthetic Ferromagnetic Thin-Film Multilayers

Magnetisation precessional dynamics have a great role in ferromagnetic thinfilms and nanostructures, where the underlying mechanisms of intrinsic and extrinsic damping are crucial for spintronic and magnonic devices. This important role drives the research activity with a goal of acquiring a better understanding and the ability to tune magnetic damping properties as desired. Research has tackled these issues through many routes linked with the ferromagnetic material type or thickness, while others have tried different aspects by including other nonmagnetic or ferromagnetic elements as dopants or adjacent layers. The effect of the additional nonmagnetic materials on the magnetic damping in ferromagnetic system is the focus in this thesis, where a range of implementations of the nonmagnetic material was studied. The role of nonmagnetic layer on damping is shown in this study as the evolution of damping as the thickness of this capping layer developed gradually from none to a partial and to a full covering layer. The effect of nonmagnetic elements was also shown when the changes of the interface takes place, the magnetic damping depends on the development of the interface and the reduction of the NM capping layer is also demonstrated. These routes helps to establish an understanding of damping and the underlying mechanisms. Linking magnetic damping with other dynamic magnetisation phenomena gives an insight into the reversal behaviour mediated by domain walls in ferromagnetic systems. Studying jointly the contributions of damping and interfacial Dzyaloshinskii- Moriya Interaction gives a better insight into the factor effecting the magnetisation dynamics. As the understanding of the magnetic damping became clearer and the underlying mechanism and effects, linking between two-magnon scattering, spinpumping and spin-mixing conductance with the crystal structure give more information. This understanding and theory initiated a study to test the theory with a new route to control magnetic damping through modifying the contributions to the total magnetic damping that come from the individual atomic layers that make up a ferromagnetic thin-film. This showed outstanding results consistent with theory and demonstrating very low damping in a new synthetic ferromagnet

Wa-Module

M.A.Hassin and A.B.Hussien introduced thefollowing concept :(a,H) is called aringoverG if H is asubgroup of groupG and aϵG and a has finite order or infinite order ,  we called the ring  (wa,+,.) ; (a,H) Ring over G wherewa= {amHan,m,nϵZ ,aϵG\H }with two binary operation + and. Such that am1 Han1 ,am2Han2ϵ wa , m1,m2,n1,n2 ϵZ1-am1Han1+am2Han2 =am1+m2 Han1+n2   .                                       2-am1Han1  .am2Han2  =am1+m2 Han1+n2  .                                        In [4] , (wa,+,.) is commutative ring with unity  aHa these lead us to give the definition of  wa-module define on the ring   which is for   any commutative ring with unity element.         The main purpose of this work is to give definition of wa-module and some  properties of Wa module many new and useful results areObtain about this concept, and we illustrate that by examples