EVALUATION OF MECHANICAL PROPERTIES AND DURABILITY OF CONCRETES CONTAINING RICE HUSK ASH

EVALUATION OF MECHANICAL PROPERTIES AND DURABILITY OF CONCRETES CONTAINING RICE HUSK ASH

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Part of #EVALUATION OF MECHANICAL PROPERTIES AND DURABILITY OF CONCRETES CONTAINING RICE HUSK ASH# :

Publishing year : 2009

Conference : Third International Conference on Concrete and Development

Number of pages : 10

Abstract: Replacement of cement with pozzolan in the production of concrete not only improves the mechanical properties and durability of concrete but also reduces the amount of consumed cement in construction projects as well. For many decades, Rice Husk Ash (RHA) as an artificial Pozzolan have been noticed for its qualities and properties. The ash remaining from burning rice husk with a high specific surface, reduces porosity and permeability and increases the durability of concrete as a result of significant pozzolanic activities and chemical activities with Calcium Hydroxide. In this paper, in order to supply typical RHA, a special furnace was designed and constructed in Amirkabir University of Technology. XRD and XRF techniques were used to determine the amorphous silica content of the burnt rice husk. Consequently, the temperature of 650 degrees centigrade and 60 minutes of burning time was found to be the best combination. Then, various experiments were carried out to determine the properties of the concretes incorporating the optimum RHA. The results show that RHA as an artificial pozzolanic material has increased strength and reduced chloride permeability leading to higher durability. As an example, the tensile strength increased by 13% after 28 days and up to 23% at 90 days.

Generating Unit Maintenance Scheduling in Power Market Based on Fairness and Competition

Generating Unit Maintenance Scheduling in Power Market Based on Fairness and Competition

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Part of #Generating Unit Maintenance Scheduling in Power Market Based on Fairness and Competition# :

Publishing year : 2013

Conference : 21st Iranian Conference on Electrical Engineering

Number of pages : 6

Abstract: In restructured power systems, the traditional approach to unit maintenance scheduling (UMS) is required to have major changes in order to be compatible with the competitive environment structures. In this paper, a new approach to unit maintenance scheduling in competitive electricity markets is presented. The main part of this study is how to treat generating companies (GenCos) fairly and how to ensure the power system security during themaintenance scheduling. This paper advances on the maintenance scheduling in the electricity market, so that it can determine which maintenance plans to be selected, while can guarantee the power system security and ensure a fair competition between GenCos. The main contribution of this study can be focused on constructing a new kind of UMS to prevent market power. In order to guarantee the power system security, a probabilistic approach to reliability analysis is presented. This probabilistic methodology is designed as a health leveling and wellbeing analysis technique. The optimal strategy profile is defined by the Genetic Algorithm and can strike the right balance between profit and security withfair competition. Finally, the simulation result in the nine-GenCo IEEE Reliability Test System (IEEE-RTS) is applied to show the applicability of the proposed framework.

Zinc Extraction from Iranian Low Grade Complex Zinc-Lead Ore by Two Native Microorganisms: Acidithiobacillus ferrooxidansand Sulfobacillus

Zinc Extraction from Iranian Low Grade Complex Zinc-Lead Ore by Two Native Microorganisms: Acidithiobacillus ferrooxidansand Sulfobacillus

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Part of #Zinc Extraction from Iranian Low Grade Complex Zinc-Lead Ore by Two Native Microorganisms: Acidithiobacillus ferrooxidansand Sulfobacillus# :

Publishing year : 2005

Conference : The 10th National Congress of Chemical Engineering of Iran

Number of pages : 9

Abstract: A mesophilic iron oxidizing bacterium, Acidithiobacillus ferrooxidans, has been isolated (33 C) from a typical chalcopyrite copper concentrate of
The Sarcheshmeh Copper Mine in the region of Kerman located in the south of Iran. In addition, a thermophilic iron oxidizing bacterium, Sulfobacillus, has been isolated (60 C) from Kooshk Lead and Zinc Mine near the city of Yazd in the center of Iran. Variation of pH, ferrous and ferric concentration on the time and effects of some factors such as temperature, cell growth, initial ferrous concentration and pH on the bioleaching of low grade complex zinc-lead ore obtained from Kooshk Lead and Zinc Mine near the city of Yazd in the center of Iran were investigated. Bioleaching experiments were performed in a 500 ml shake flask containing 250 ml of medium, 5% (v / v) inoculum and 2% (w / v) of low grade ore. Control bioleaching tests were performed with sterilized or 250 ml of medium without inoculum by adding 5 ml of 0.5% (v / v) formalin in ethanol. The results indicate that the efficiency of zinc extraction is dependent on all of the above mentioned variables; especially temperature and initial ferrous concentration have more effect than other factors for these microorganisms. In addition, the results show that maximum Zn recovery was achieved using a thermophilic culture. Copper dissolution reached 58% with Sulfobacillus while it was 51% with
Acidithiobacillus ferrooxidans at pH = 1.5, initial Fe2 + concentration = 7000 and 9000 mg / lit for mesophilic and thermophilic strains respectively, after 30 days.

Assessing the Engineering Properties of Travertine Using Their Physical Properties (A case study on Sarab mine)

Assessing the Engineering Properties of Travertine Using Their Physical Properties (A case study on Sarab mine)

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Part of #Assessing the Engineering Properties of Travertine Using Their Physical Properties (A case study on Sarab mine)# :

Publishing year : 2016

Conference : 7th International Conference on Economics and Management

Number of pages : 9

Abstract: Travertine in sarab-goltape mine can be used in engineering projects such as borrow materials, construction stones (malone, rubble) as well as non-structural lightweight concrete. It is important to investigate the petrographic, physical, and engineering geological characteristics of these rocks in order to optimize their use. In this study, the physical and petrographic characteristics of these rockshave been studied to evaluate geotechnical and engineering properties. This study shows that the existence of micritic cement leads to an increase in uniaxial compressive strength. Furthermore, the intergranular porosity is considered in the evaluation of the trsvertine strength and of highly affects the rock resistance of the samples.

AMENABILITY OF SEMIGROUP ALGEBRAS AND THEIR SECOND DUALS

AMENABILITY OF SEMIGROUP ALGEBRAS AND THEIR SECOND DUALS

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Part of #AMENABILITY OF SEMIGROUP ALGEBRAS AND THEIR SECOND DUALS# :

Publishing year : 2006

Conference : Sixteenth Seminar on Mathematical Analysis and its Applications

Number of pages : 5

Abstract: We recall the definitions of amenable and weakly amenable Banach algebras, and give equivalent formulations. We define the semigroup algebra of a semigroup, and explain when these algebras are amenable. We explain that their second duals are never amenable when the semigroup is infinite. We also state that the second dual of a group algebra L ^ 1 (G), for a locally compact group G, is weakly amenable if and only if G is finite.

Assessment of Parameters Effecting Stability of Secant piles wall Using Plaxis 3D

Assessment of Parameters Effecting Stability of Secant piles wall Using Plaxis 3D

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Part of #Assessment of Parameters Effecting Stability of Secant piles wall Using Plaxis 3D# :

Publishing year : 2012

Conference : Ninth International Congress of Civil Engineering

Number of pages : 7

Abstract: Secant piles wall is one of the suitable methods of wall construction, when involving deep vertical excavations; Is cast in situ before excavation is carried out. Technical and economical benefits are considered for this technique. These piles are constructed in various forms, of them is secant form. In this paper, firstly, the stress and moment generated along the soil-pile and being placed alongside each other are presented. In continuation, the parametric study of parameter effects is the behavior of secant piles using Plaxis 3D Foundation software (Ver. 1.5) is carried out subsequently. Obtained results reveal the following points: Use of secant piles around the trench specially with increasing internal friction angle () causing reduction of displacements. The variation of displacements obeys a constant trend, when value of 40. Increase of value of parameters such as embedded depth and lateral rigidity factor & gt; 0.01 and diameter of the secant pile will result in reduction of their displacements. The value of the spacing (s) is increasing with respect to their diameter (D), and then the value of s = 2.5D and then it will increase to a decreasing trend and finally reaches a constant value at s8D

EVALUATION OF THE EFFECT OF WIND FORCINGIN THE LOCAL WAVE PROPAGATION MODELS

EVALUATION OF THE EFFECT OF WIND FORCINGIN THE LOCAL WAVE PROPAGATION MODELS

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Part of #EVALUATION OF THE EFFECT OF WIND FORCINGIN THE LOCAL WAVE PROPAGATION MODELS# :

Publishing year : 2014

Conference : Eleventh International Conference on Coastal, Ports and Marine Structures

Number of pages : 5

Abstract: In recent years, the generation and propagation wave models are widely applied in both local and large scales. In this way, several basic studies have been carried out to produce waveproperties in large scale such as Iranian Seas Wave Modeling (ISWM) and monitoring and modeling studies of Iranian coasts.

Synthesis and Application of Silica Aerogel-MWCNT Nanocomposites for Adsorption of Organic Pollutants

Synthesis and Application of Silica Aerogel-MWCNT Nanocomposites for Adsorption of Organic Pollutants

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Part of #Synthesis and Application of Silica Aerogel-MWCNT Nanocomposites for Adsorption of Organic Pollutants# :

Publishing year : 2009

Conference : Third Conference on Nanostructures

Number of pages : 4

Abstract: Silica aerogel-Multi-wall carbon nanotube composite is synthesized successfully with a water glass precursor and ambient drying method. Pure silica aerogels are so fragile that can not be used practically. Carbon nanotube (MWCNT) is used as a reinforcement for the reinforcement of mechanical properties of pure silica aerogels. Different percentages of MWCNT at different stages of synthesis were added to achieve the best quality of reinforced aerogels. Results showed that inserting a small amount of MWCNT caused to reach monolithic silica aerogels. In the best amount of added MWCNT, monolith nanocomposite was produced with a surface area of 800 m2 / g and a 140 contact angle. Results show that silica aerogels and reinforced composites have excellent adsorption properties for organic pollutants removal from water. Adsorption capacity of about 5 times of composite weight for adsorption of benzene, toluene, n-hexane, petrol, gasoline and petroleum was observed.

Chemical composition of the essential oil of Perovskia atriplicifolia Benth. growing wiled in Iran

Chemical composition of the essential oil of Perovskia atriplicifolia Benth. growing wiled in Iran

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Part of #Chemical composition of the essential oil of Perovskia atriplicifolia Benth. growing wiled in Iran# :

Publishing year : 2014

Conference : The 2nd National Conference on Medicinal Plants and Sustainable Agriculture

Number of pages : 7

Abstract: The chemical composition of the volatile oil from the flower parts of the Perovskia atriplicifolia Karel. Has been studied by GC and GC-MS. Twenty-four components were identified. 1,8-Cineole (18.65%), -3-Carene (11.23%), -Pinene (9.98%), Valencene (8.45), -Humulene (7.55%), -Caryophyllene (7.19%), Neryl acetate (6.63% ) And Borneol (5.60%) were found to be the major constituents of the oil. The oil of P. atriplicifolia was characterized by high content of monoterpenes (67.26%), whereas sesquiterpenes contained only 32.74% of essential oil.

A Review: Is LOT Universal among People Who Speak Different Oral Languages?

A Review: Is LOT Universal among People Who Speak Different Oral Languages?

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Part of #A Review: Is LOT Universal among People Who Speak Different Oral Languages?# :

Publishing year : 2015

Conference : Second International Conference on Behavioral Sciences and Social Studies

Number of pages : 5

Abstract: LOT, or 'mentalese' in Fodor's term, has been the subject of study by several philosophers for many years, but recently, cognitive psychologists have also debated this controversial issue. It is clear that thought is manifested by words but the Kind of relationship between these two is still blur. The question is whether people using different languages speak differently Whether someone speaking English and one speaking Persian would think differently just because of the language they use Many people ask bilingualals or multilanguals what language or languages they think When people do their activities, for example, walking, cooking, riding, etc., their Consequently, LOT is universal or the 'cognitive architecture' of all human beings is the same. But i It is just realized in variousforms of oral languages. In the meanwhile, animals are also equipped with LOT