In this research, damping properties for composite materials were evaluated using logarithmic decrement method to study the effect of reinforcements on the damping ratio of the epoxy matrix. Three stages of composites were prepared in this research. The first stage included preparing binary blends of epoxy (EP) and different weight percentages of polysulfide rubber (PSR) (0%, 2.5%, 5%, 7.5% and 10%). It was found that the weight percentage 5% of polysulfide was the best percentage, which gives the best mechanical properties for the blend matrix. The advantage of this blend matrix is that; it mediates between the brittle properties of epoxy and the flexible properties of a blend matrix with the highest percentage of PSR. The second stage included reinforcing the best blend matrix of epoxy-polysulfide (the blend matrix with the best percentage of polysulfide resulted from the previous stage), by different volume percentages of short fibers (Carbon& Glass) separately and randomly. The volume percentages of fibers were (2.5%, 5%, 7.5%, and 10%). The third stage included reinforcing the blend composites with highest percentages of carbon and glass fiber, by different weight percentages of nano-particles (Red mud& Fly ash) separately. The weight percentages of particles were (0.5%, 1%, 1.5%, and 2%). The experimental results showed that blending polysulfide rubber with epoxy increased the damping ratio. As for reinforcement materials, they decreased the damping ratio, where glass fiber composites have significantly higher damping ratio than other composites.
The histological structure of integument in Mastacembelus mastacembelus have been investigated from skin fragments cut from nine regions at body surface. The results revealed that the integument of the fish investigated comprises three principal layers- the epidermis, the dermis (corium) and the subcutis-All the three principal layers may further be divided into secondary layers according to the function performed by their cells. The epidermis may further divided into three layers- the outermost epithelial coverage, the middle layer and the basal layer (stratum germinatiuum)-The dermis consists of a relatively thin upper layer of loose vascular connective tissue called the stratum laxum and a thick lower compact layer- the stratum compactu
... Show MoreIn this study, the adsorption of Zn (NO3)2 is carried out by using surfaces of malvaparviflora. The validity of the adsorption is evaluated by using atomic absorption Spectrophotometry through determination the amount of adsorbed Zn (NO3)2. Various parameters such as PH, adsorbent weight and contact time are studied in terms of their effect on the reaction progress. Furthermore, Lagergren’s equation is used to determine adsorption kinetics. It is observed that high removal of Zn (NO3)2 is obtained at PH=2. High removal of Zn (NO3)2 is at the time equivalent of 60 min and reaches equilibrium,where 0.25gm is the best weight of adsorbant . For kinetics the reaction onto malvaparviflora follows pseudo first order Lagergren’s equation.
Flexible pavement design and analysis were carried out in the past with semi-experimental methods, using elastic characteristics of pavement layers. Due to the complex interferences between various layers and their time consumption, the traditional pavement analysis, and design methods were replaced with fast and powerful methods including the Finite Element Method (FEM) and the Discrete Element Method (DEM). FEM requires less computational power and is more appropriate for continuous environments. In this study, flexible pavement consisting of 5 layers (surface, binder, base, subbase, and subgrade) had been analyzed using FEM. The ABAQUS (6.14-2) software had been utilized to investigate the influence of the base layer depth on ver
... Show MoreSustainability is a concept embodied in traditional architecture around the world since ancient times through spontaneous experimental compatibility with the environment and efficient exploitation of the natural resources of the environment according to a rapid development of trial and error over the years . Architecture was the basic means that man devised to protect him from the harsh conditions of the external environment by exploiting natural energy sources such as the sun, wind, and soil capabilitie, Many of the principles of sustainability overlapped with the social organization and human behavior of the community as it was reflected in the urban production at the level of standards of city planning and urban agglomerations as well
... Show MoreThe Ge0.4Te0.6 alloy has been prepared. Thin films of Ge0.4Te0.6 has been prepared via a thermal evaporation method with 4000A thickness, and rate of deposition (4.2) A/sec at pressure 2x10-6 Torr. The A.C electrical conductivity of a-Ge0.4Te0.6 thin films has been studied as a function of frequency for annealing temperature within the range (423-623) K, the deduced exponent s values, was found to decrease with increasing of annealing temperature through the frequency of the range (102-106) Hz. It was found that, the correlated barrier hopping (CBH) is the dominant conduction mechanism. Values of dielectric constant ε1 and dielectric loss ε2 were found to decrease with frequency and increase with temperature. The activation energies have
... Show MorePublic relations have become vital functions in modern institutions in the complex business world. They play an important role in facilitating the process of communication between the institution and its audiences and achieve mutual understanding between the parties as public relations play this important role based on research and analysis, policy formulation and programming programs and communication with the public.
The significance of this research comes from the challenges faced by public relations in state institutions. Misunderstandings and ambiguities still plague most workers in this field, especially in defining the concept, objectives and basic functions of public rela
... Show MoreThe species Spongilla lacustris was identified for the first time in Iraq, it was found during winter 1998 in an irrigation canal within the campus of the University of Baghdad (Jadiriah), water is drawn from Tigris river. The specimens were found in water samples of sizes ranging between 5-50 cm with yellowish color . It was found in two habitats , one as attached on submerged aquatic plant Ceratophyllum sp., and the other on the canal bottom (concret material). Some physico- chemical characters were determined including conductivity ,salinity , pH, total alkalinity, total hardness, Ca ,Mg ,anddissolved oxygen. Water quality was fresh , alkaline, hard and well aerated.
This study includes the rebuilding of cities that war destroyed, which include some of the special policies that should be followed in order to build cities that war destroyed and which have importance in the national and humanitarian level, as well as some international experiences discussed including Warsaw, and the regional experiences, including Lebanon and concentrates on the foundation stone and evaluate it with global and regional experiences so that we can concluded with an integrated strategy that will achieve the best results in doing the reality that we live in these cities which are suffering from such disasters . In order to achieve the best goals we should review the best concepts and theories related to reconstruction afte
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