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The New Software for Research and the Modelling of Grown-in Microdefects in Dislocation-Free Silicon Single Crystals
Vitalyi Igorevich Talanin,
Igor Evgenievich Talanin,
Vladislav Igorevich Lashko
Issue:
Volume 3, Issue 1, February 2018
Pages:
1-5
Received:
5 December 2017
Accepted:
18 December 2017
Published:
11 January 2018
Abstract: As a virtual experimental device for research and the modelling of grown-in microdefects formation in dislocation-free silicon single crystals the software is proposed. The software is built on the basis on diffusion model of grown-in microdefects formation and allows the use of computer to investigate the defect structure of silicon monocrystals with a diameter up to 400 mm.
Abstract: As a virtual experimental device for research and the modelling of grown-in microdefects formation in dislocation-free silicon single crystals the software is proposed. The software is built on the basis on diffusion model of grown-in microdefects formation and allows the use of computer to investigate the defect structure of silicon monocrystals w...
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Effect of Inertia Constant on Generator Frequency and Rotor Angle
Ngyarmunta Alan Audu,
Odaba Alphaeus,
Talatu Adamu
Issue:
Volume 3, Issue 1, February 2018
Pages:
6-11
Received:
25 November 2017
Accepted:
23 December 2017
Published:
1 February 2018
Abstract: Inertia constant of a rotating system describes the initial transient, frequency and rotor angle behavior of that system when subjected to a real power disturbance. Therefore, the inertia constant of a system can be a useful tool when investigating the frequency and rotor angle stability of a system. The use of the swing equation gives us a viable method for estimating the inertia constant, if a measurement of that can provide time stamps measurements of the frequency and power dynamics during a disturbance. In this project work, effect of inertia constant of synchronous generator (machine constant) on its frequency and rotor angle is investigated. Swing equation is used for modeling the dynamics of the system. It is then built and simulated using MATLAB. The analysis is done by observing how the frequency and rotor angle changes when the inertia constant is varied while keeping all system parameters constant. The study is extended to investigate the dynamics of such system with very high and those with very low inertia constant and the results show that the higher the value of the inertia constant, the higher the settling time and of course the maximum overshoot.
Abstract: Inertia constant of a rotating system describes the initial transient, frequency and rotor angle behavior of that system when subjected to a real power disturbance. Therefore, the inertia constant of a system can be a useful tool when investigating the frequency and rotor angle stability of a system. The use of the swing equation gives us a viable ...
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Alkali-Aggregate Reaction: Definition, Influence and Control
Juliana Maria McCartney da Fonseca,
Vanessa Karla Barbosa de Souza,
Deborah Grasielly Cipriano da Silva,
Dione Luiza da Silva,
Eliana Cristina Barreto Monteiro
Issue:
Volume 3, Issue 1, February 2018
Pages:
12-20
Received:
29 December 2017
Accepted:
11 February 2018
Published:
14 March 2018
Abstract: The alkali-aggregate reaction is a pathological manifestation due from chemical processes of interaction of reactive minerals that are present in some aggregates, and alkali hydroxides from Portland cement, water kneading and external agents dissolved in the solution present in the pores of concrete. It is a reaction that occurs slowly, but may cause irreparable damage, for example with cracks that impair the mechanical strength and durability of the affected structure. The main objective of this work is to expand the existing knowledge about the evolution of this pathological manifestation in order to contribute to eradicate this problem in the construction works. The methodology used in the article includes a literature review that addresses a history of occurrence of alkali-aggregate reaction in Brazil and around the world, its definition, the types of reaction, the factors that influence it, control methods and some cases in Metropolitan region of Recife that had this pathological manifestation during the construction process and during its lifetime. The article here presented is intended to contribute to spreading a deeper understanding of this pathological manifestation as well, pointing out mitigating actions of its occurrence, it is a relevant tool for the technical means, the expected result with this production is to increase the knowledge of the theme proposed, as the increasing number of occurrence of this pathological manifestation in concrete structures.
Abstract: The alkali-aggregate reaction is a pathological manifestation due from chemical processes of interaction of reactive minerals that are present in some aggregates, and alkali hydroxides from Portland cement, water kneading and external agents dissolved in the solution present in the pores of concrete. It is a reaction that occurs slowly, but may cau...
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Water Coning Prediction: An Evaluation of Horizontal Well Correlations
Anietie Ndarake Okon,
Dulu Appah
Issue:
Volume 3, Issue 1, February 2018
Pages:
21-28
Received:
30 January 2018
Accepted:
11 February 2018
Published:
14 March 2018
Abstract: Oil production from bottom-water drive reservoirs is characterized by water production related problem - water coning. Most times, horizontal wells are used to attenuate this production challenge. That notwithstanding, overtime, depending on the production rate, water coning is also experienced with horizontal wells. Therefore, several correlations have been developed to predict the critical rate, breakthrough time and water-cut performance after breakthrough in horizontal wells. However, limited studies have evaluated the predictions of these developed water coning correlations. Therefore, an evaluation has been made to predict the various water coning correlations in horizontal wells. The obtained results show that the critical rate directly depends on the stand-off to drainage width and horizontal well length to drainage width ratios. Also, it is shown that the breakthrough time directly depends on the horizontal well length to drainage width ratio. Furthermore, the correlations developed from water-cut data for the prediction of post-water behaviour (i.e., water-cut performance) after breakthrough indicate more proficient water-cut profile than the correlations developed from water-oil ratio. Therefore, to prolong the occurrence of water coning in horizontal wells, the ratios of stand-off to drainage width and horizontal well length to drainage width should be considered to achieve maximum critical oil rate and breakthrough time in bottom-water reservoirs.
Abstract: Oil production from bottom-water drive reservoirs is characterized by water production related problem - water coning. Most times, horizontal wells are used to attenuate this production challenge. That notwithstanding, overtime, depending on the production rate, water coning is also experienced with horizontal wells. Therefore, several correlations...
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Determining and Modelling of Thermal and Rheological Properties of Cashew Apple By-Products
Rogéria Helen Lima Vidal,
Fábia Bocayuva Carvalho,
Camila Gambini Pereira
Issue:
Volume 3, Issue 1, February 2018
Pages:
29-39
Received:
2 February 2018
Accepted:
16 February 2018
Published:
16 March 2018
Abstract: This study aims to determine thermal and rheological properties of blended cashew apple juice (cajuína), nectar, and pulp. The effects of temperature on rheological properties were evaluated and the behavior was adjusted to rheological models. Comparing the thermal properties of cashew products, cajuína showed lower density, and higher values of thermal conductivity, thermal diffusivity and specific heat. Equations providing these properties in function of temperature were obtained, and presented good fits. Cajuína and cashew apple pulp were well characterized by the Ostwald-de-Waelle and Hershel-Bulkley models, respectively, while for cashew apple nectar, two behaviors were observed depending on the temperature used.
Abstract: This study aims to determine thermal and rheological properties of blended cashew apple juice (cajuína), nectar, and pulp. The effects of temperature on rheological properties were evaluated and the behavior was adjusted to rheological models. Comparing the thermal properties of cashew products, cajuína showed lower density, and higher values of th...
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