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Formulae for the frequency equations of beam-column system carrying a fluid storage tank
Tamer A. El-Sayed,Said H. Farghaly 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.1
In this work, a mathematical model of beam-column system carrying a double eccentric end mass system is investigated, and solved analytically based on the exact solution analysis. The model considers the case in which the double eccentric end mass is a rigid storage tank containing fluid. Both Timoshenko and Bernoulli-Euler beam bending theories are considered. Equation of motion, general solution and boundary conditions for the present system model are developed and presented in dimensional and non-dimensional format. Several important non-dimensional design parameters are introduced. Symbolic and/or explicit formulae of the frequency and mode shape equations are formulated. To the authors knowledge, the present reduced closed form symbolic and explicit frequency equations have not appeared in literature. For different applications, the results are validated using commercial finite element package, namely ANSYS. The beam-column system investigated in this paper is significant for many engineering applications, especially, in mechanical and structural systems.
Exact vibration of Timoshenko beam combined with multiple mass spring sub-systems
Tamer A. El-Sayed,Said H. Farghaly 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.6
This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded beam system carrying ends consisting of non-concentrated tip masses and three spring-two mass subsystems. The influence of system design and sub-system parameters on the combined system characteristics is the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system is included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. Sub-systems are attached to center of gravity eccentric points out of the beam span. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including developed shear force frequency dependent terms, due to the sub–system suspension, have been formulated. Exact formulae for the modal frequencies and the modal shapes have been derived. Based on these formulae, detailed parametric studies are carried out. The geometrical and mechanical parameters of the system under study have been presented in non-dimensional analysis. The applied mathematical model is presented to cover wide range of mechanical, naval and structural engineering applications.
Prediction of creep in concrete using genetic programming hybridized with ANN
Osama A. Hodhod,Tamer E. Said,Abdulaziz M. Ataya 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.5
Time dependent strain due to creep is a significant factor in structural design. Multi-gene genetic programming (MGGP) and artificial neural network (ANN) are used to develop two models for prediction of creep compliance in concrete. The first model was developed by MGGP technique and the second model by hybridized MGGP-ANN. In the MGGP-ANN, the ANN is working in parallel with MGGP to predict errors in MGGP model. A total of 187 experimental data sets that contain 4242 data points are filtered from the NU-ITI database. These data are used in developing the MGGP and MGGP-ANN models. These models contain six input variables which are: average compressive strength at 28 days, relative humidity, volume to surface ratio, cement type, age at start of loading and age at the creep measurement. Practical equation based on MGGP was developed. A parametric study carried out with a group of hypothetical data generated among the range of data used to check the generalization ability of MGGP and MGGP-ANN models. To confirm validity of MGGP and MGGP-ANN models; two creep prediction code models (ACI209 and CEB), two empirical models (B3 and GL 2000) are used to compare their results with NUITI database.
Analysis and Mitigation of Ground Grid Lightning Potential Rise
Ahmed Taher,Abdelrahman Said,Tamer Eliyan,Abdelsalam Hafez 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3
Grid design depends mainly on bringing grounding resistance, mesh voltage, and step voltage below tolerable limits when subjected to any ground fault. But, it should be noticed that the grid performance has to be tested when subjected to lightning stroke. The performance of the grid under impulse current diff ers than that of under power–frequency fault. In this paper ATP-EMTP software is used to analyze the performance of the ground grid when subjected to lightning stroke. Different methods are suggested to mitigate the lightning overvoltage, all of these methods depend mainly on modifying the design by adding more conductors or rods at specific places. The case study under consideration is Al-Mostakbal substation 220/22 kV which is located in Al-Mostakbal city, Cairo, Egypt.
Waleed A. El-Said,Abdullah S. Al‐Bogami,Wael Alshitari,Deia A. El-Hady,Tamer S. Saleh,Mohamed A. El-Mokhtar,최정우 한국바이오칩학회 2021 BioChip Journal Vol.15 No.3
As continues increasing the COVID-19 infections, there is an urgent need for developing fast, simple, selective, and accurate COVID-19 biosensors. A highly uniform gold (Au) microcuboid pattern was used as a microelectrode that allowed monitoring a small analyte. The electrochemical biosensor was used to monitor the COVID-19 S protein within a concentration range from 100 to 5 pmol L −1 ; it showed a lower detection limit of 276 fmol L −1 . Finally, the developed COVID-19 sensor was used to detect a positive sample from a human patient obtained through a nasal swab; the results were confirmed using the PCR technique. The results showed that the SWV technique showed high sensitivity towards detecting COVID-19 and good efficiency for detecting COVID-19 in a positive human sample.