Documents published in Scipedia

• Determination of loop length, tightness factor and porosity of single jersey knitted fabric

  E. Eltahan, M. Sultan, A. Mito

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  After fabric relaxation, there is a reduction in wale and course density due to a reduction in loop length and this actually will affect the fabric properties. Then, it is useful to find a relation between loop length and courses and wales per unit length as well as the yarn thickness because wales and courses per unit length can be easily measured at any state while it is difficult to measure the loop length in the knitted fabrics. Therefore, it is required to find an equation, through which the value of loop length can be easily calculated from the measured values of courses and wales per unit length at any state after the knitting process. In this work estimated equations to calculate the knitted loop length for open to normal structure and for normal to compact structure are developed. By comparing the value of the loop length predicted from this work with the other mentioned models, it was found that the calculated values are very near to the L value of the case study, so the developed equations are acceptable. The tightness factor and the porosity of single jersey fabrics were also calculated theoretically.

  Abstract
  After fabric relaxation, there is a reduction in wale and course density due to a reduction in loop length and this actually will affect the fabric properties. Then, it is [...]

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• Weight optimization of offshore supply vessel based on structural analysis using finite element method

  A. Elhewy, A. Hassan, M. Ibrahim

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  Ship design process usually relies on statistics and comparisons with existing ships, rather than analytical approaches and optimization techniques. Designers found this way as the best to fulfil the owner’s requirements, but better solutions, for both the shipyard and the owner may exist. Assessing ship life cycle cost is one of the most attractive tasks for shipyard during early design stage. Structural optimization can be used to achieve that task. In this paper, a comprehensive study on the structural optimization of an offshore supply vessel (OSV), as a case study, is presented. Detailed structural modeling of the vessel is created. Various environmental loads acting on the ship hull such as still water loads and wave induced loads are briefly explained. Different loading conditions and corresponding structural responses have been investigated to assign the most severe one on the vessel. The basic concept of structural optimization and optimization characteristics is highlighted. Blind search optimization technique is applied and approximately forty-two percent weight and cost savings are found by comparing the weight of various design scenarios together without showing any structural inadequacy.

  Abstract
  Ship design process usually relies on statistics and comparisons with existing ships, rather than analytical approaches and optimization techniques. Designers found this way [...]

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• Performance evaluation for solar liquid desiccant air dehumidification system

  M. Elhelw

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In this paper, a solar liquid desiccant air conditioning (SLDAC) system has been studied. The effect of changing evacuated tube collector area on the performance of the SLDAC system was fulfillment. This inquest was done over all a year in Borg Al-Arab city located in the Northern region of Egypt. Meteorological data, such as hourly average solar radiations and temperatures, were needed to achieve this research. The hourly cooling loads were determined by using Hourly Analysis Program (HAP) 4.7. These loads are wall, illumination, people, and equipment loads. Then, the hourly differences of different parameters such as amount of water absorbed in conditioner, amount of water desorbed in regenerator, hot water temperature and coefficient of the performance were calculated. In addition, the maximum solar thermal energy was determined to meet the regeneration demand according to the hourly average solar radiation data. For 220 m2 evacuated tube collector area, the maximum required heat energy is obtained as 38, 286 kW h on December, while using solar energy, will save energy by 30.28% annual value.

  Abstract
  In this paper, a solar liquid desiccant air conditioning (SLDAC) system has been studied. The effect of changing evacuated tube collector area on the performance of the SLDAC [...]

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• Analytical solution of strongly nonlinear Duffing oscillators

  A. El-Naggar, G. Ismail

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In this paper, a new perturbation technique is employed to solve strongly nonlinear Duffing oscillators, in which a new parameter α=α(ε)α=α(ε) is defined such that the value of α is always small regardless of the magnitude of the original parameter εε. Therefore, the strongly nonlinear Duffing oscillators with large parameter ε are transformed into a small parameter system with respect to αα. Approximate solution obtained by the present method is compared with the solution of energy balance method, homotopy perturbation method, global error minimization method and lastly numerical solution. We observe from the results that this method is very simple, easy to apply, and gives a very good accuracy not only for small parameter εbut also for large values of ε.

  Abstract
  In this paper, a new perturbation technique is employed to solve strongly nonlinear Duffing oscillators, in which a new parameter α=α(ε)α=α(ε) is defined such that the [...]

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• Nanoparticles Ni electroplating and black paint for solar collector applications

  J. Nady, A. Kashyout, S. Ebrahim, M. Soliman

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  A nanoparticles layer of bright nickel base was deposited on copper substrates using electrodeposition technique before spraying the paint. IR reflectance of the paint was found to be around 0.4 without bright nickel layer and the reflectance increased to 0.6 at a Ni layer thickness of 750 nm. The efficiency of the constructed solar collectors using black paint and black paint combined with bright nickel was found to be better than black paint individually. After aging tests under high temperature, Bright nickel improved the stability of the absorber paint. The collector optical gain FR(τα) was lowered by 24.7% for the commercial paint and lowered by 19.3% for the commercial paint combined with bright nickel. The overall heat loss FR(UL) was increased by 3.3% for the commercial paint and increased by 2.7% for the commercial paint combined with bright nickel after the temperature aging test.

  Abstract
  A nanoparticles layer of bright nickel base was deposited on copper substrates using electrodeposition technique before spraying the paint. IR reflectance of the paint was [...]

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• Nonlinear behavior of RC beams strengthened with strain hardening cementitious composites subjected to monotonic and cyclic loads

  A. Khalil, E. Etman, A. Atta, M. Essam

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  Ultra High Performance Strain Hardening Cementitious Composites (UHP-SHCC) are useful for strengthening or repairing concrete members. However there is a need to use refined analytical tools to simulate response of strengthened system. In this study, ABAQUS finite element program is used to numerically perform a parametric study including two major groups. Each group contains nine specimens strengthened from the tension side with variable thickness of UHP-SHCC and reinforced with variable reinforcement ratios embedded in the strengthening layer. Two types of loading were applied: monotonic loading for the first group and cyclic loading for the second group. ABAQUS CPS4R mesh element nonlinear is used to model the concrete, while truss element nonlinear is used to model longitudinal and transverse steel reinforcement. The numerical results obtained are in good agreement with the experimental work found in the literature. The results from the parametric study showed that it is sufficient to use 1.2% additional reinforcement ratio embedded in the strengthening layer for beams strengthened with UHP-SHCC to eliminate the observed early strain localization and to gain adequate ductility under both static and cyclic loadings.

  Abstract
  Ultra High Performance Strain Hardening Cementitious Composites (UHP-SHCC) are useful for strengthening or repairing concrete members. However there is a need to use refined [...]

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• The Application of Gorman’s Eigen Values to The Industrial Sewing Machine’s Needle Vibration

  S. Gholmy, I. Hawary

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  The free vibration of the sewing needle is divided into lateral free vibrations and an axial free vibration. In this work a theoretical study that concerns the free lateral vibrations will be applied to the sewing needle by the use of Gorman’s Eigen values (Daniel, 1975) technique. The study will be divided into the following: needles with constant cross-section (with classical and non classical boundary conditions) and needles with variable cross-section (conical and stepped). For all the different shapes of needles (Gorman’s classifications) the linear natural frequency in stitches per min (SPM) will be calculated by the use of Gorman’s Eigen values via special tables and graphs. It was found that the linear fundamental natural frequencies of the following: clamped free sewing needle (CF) is 21, 548 SMP, clamped simple sewing needle (CS) is 94, 522 SMP while for free–free needle (FF) for n = 2 is 137, 130 SMP. For each type the Eigen value β was selected due to the sewing needle boundary conditions. The ratio between the lowest (CF) linear natural frequency and the highest (FF) one is 16%. In this work the selected sewing needle material was steel with E = 206 GPa and specific weight 785, 000 N/m3.

  Abstract
  The free vibration of the sewing needle is divided into lateral free vibrations and an axial free vibration. In this work a theoretical study that concerns the free lateral [...]

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• Long term study of mechanical properties, durability and environmental impact of limestone cement concrete

  A. Diab, A. Elmoaty, A. Aly

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In this study, properties of limestone cement concrete containing different replacement levels of limestone powder were examined. It includes 0%, 5%, 10%, 15%, 20% and 25% of limestone powder as a partial replacement of cement. Silica fume was added incorporated with limestone powder in some mixes to enhance the concrete properties. Compressive strength, splitting tensile strength and modulus of elasticity were determined. Also, durability of limestone cement concrete with different C3A contents was examined. The weight loss, length change and cube compressive strength loss were measured for concrete attacked by 5% sodium sulfate using an accelerated test up to 525 days age. The corrosion resistance was measured through accelerated corrosion test using first crack time, cracking width and steel reinforcement weight loss. Consequently, for short and long term, the use of limestone up to 10% had not a significant reduction in concrete properties. It is not recommended to use blended limestone cement in case of sulfate attack. The use of limestone cement containing up to 25% limestone has insignificant effect on corrosion resistance before cracking.

  Abstract
  In this study, properties of limestone cement concrete containing different replacement levels of limestone powder were examined. It includes 0%, 5%, 10%, 15%, 20% and 25% [...]

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• Improvement of biodiesel methanol blends performance in a variable compression ratio engine using response surface methodology

  Y. Bharadwaz, B. Rao, V. Rao, C. Anusha

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  The main objective of this work was to improve the performance of biodiesel–methanol blends in a VCR engine by using optimized engine parameters. For optimization of the engine, operational parameters such as compression ratio, fuel blend, and load are taken as factors, whereas performance parameters such as brake thermal efficiency (Bth) and brake specific fuel consumption (Bsfc) and emission parameters such as carbon monoxide (CO), unburnt hydrocarbons (HC), Nitric oxides (NOx) and smoke are taken as responses. Experimentation is carried out as per the design of experiments of the response surface methodology. Optimization of engine operational parameters is carried out using Derringers Desirability approach. From the results obtained it is inferred that the VCR engine has maximum performance and minimum emissions at 18 compression ratio, 5% fuel blend and at 9.03 kg of load. At this optimized operating conditions of the engine the responses such as brake thermal efficiency, brake specific fuel consumption, carbon monoxide, unburnt hydrocarbons, nitric oxide, and smoke are found to be 31.95%, 0.37 kg/kW h, 0.036%, 5 ppm, 531.23 ppm and 15.35% respectively. It is finally observed from the mathematical models and experimental data that biodiesel methanol blends have maximum efficiency and minimum emissions at optimized engine parameters.

  Abstract
  The main objective of this work was to improve the performance of biodiesel–methanol blends in a VCR engine by using optimized engine parameters. For optimization of the [...]

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• Hall effects on an unsteady magneto-convection and radiative heat transfer past a porous plate

  S. Das, S. Guchhait, R. Jana, O. Makinde

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  Hall effects on an unsteady magnetohydrodynamic (MHD) free convective flow of a viscous incompressible electrically conducting optically thick radiating fluid past a vertical porous plate in the presence of a uniform transverse magnetic field are examined. The governing equations are solved numerically using the fourth-order Runge–Kutta–Fehlberg method with the shooting technique. Effects of the pertinent parameters on the flow field, temperature distribution, shear stresses and rate of heat transfer at the plate are presented in graphs and tables followed by a quantitative discussion. The results reveal that the flow field and the temperature distribution are greatly influenced by thermal radiation parameter. Hall currents moderate the flow field significantly. Suction (or injection) has a profound effect on the boundary layer thickness in which the suction reduces the thermal boundary layer thickness whereas injection thickens it.

  Abstract
  Hall effects on an unsteady magnetohydrodynamic (MHD) free convective flow of a viscous incompressible electrically conducting optically thick radiating fluid past a vertical [...]

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