Open Access Original Research Article

Behavior of Columns Confined With FRP Fabrics under Repeated Lateral Loads

Hesham A. Haggag, Nagy F. Hanna, Ghada G. Ahmed

Journal of Engineering Research and Reports, Page 1-19
DOI: 10.9734/jerr/2019/v6i416954

The axial strength of reinforced concrete columns is enhanced by wrapping them with Fiber Reinforced Polymers, FRP, fabrics.  The efficiency of such enhancement is investigated for columns when they are subjected to repeated lateral loads accompanied with their axial loading.  The current research presents that investigation for Glass and Carbon Fiber Reinforced Polymers (GFRP and CFRP) strengthening as well.  The reduction of axial loading capacity due to repeated loads is evaluated. The number of applied FRP plies with different types (GFRP or CFRP) are considered as parameters in our study. The study is evaluated experimentally and numerically.  The numerical investigation is done using ANSYS software. The experimental testing are done on five half scale reinforced concrete columns.  The loads are applied into three stages. Axial load are applied on specimen in stage 1 with a value of 30% of the ultimate column capacity. In stage 2, the lateral loads are applied in repeated manner in the existence of the vertical loads.  In the last stage the axial load is continued till the failure of the columns. The final axial capacities after applying the lateral action, mode of failure, crack patterns and lateral displacements are recorded.   Analytical comparisons for the analyzed specimens with the experimental findings are done.  It is found that the repeated lateral loads decrease the axial capacity of the columns with a ratio of about (38%-50%).  The carbon fiber achieved less reduction in the column axial capacity than the glass fiber.  The column confinement increases the ductility of the columns under the lateral loads.

Open Access Original Research Article

A Critical Analysis of Multi-Regime Fundamental Equations

Emmanuel Akweittey, Gabriel O. Fosu

Journal of Engineering Research and Reports, Page 1-8
DOI: 10.9734/jerr/2019/v6i416955

Aims/ Objectives: Multi-regime fundamental models use two or more equations to describe the association among the main maroscopic traffic variables encountered in traffic analysis. The paper investigates specific properties of some multi-phase speed-density equations. 

Methodology: It first compares the characteristics of each of these equations by solving the nonlinear continuity traffic equation. 

Results: It was observed that predicting vehicular trajectories with these model equations could lead to misinformation. The kinematic wave and stable shockwave properties of these models were also ascertained. 

Conclusion: Based on the results, it was concluded that it would be more cumbersome to explain nonlinear traffic characteristics when these two and three regime models are adopted.

Open Access Original Research Article

Modelling Rainfall Intensity by Optimization Technique in Abeokuta, South-West, Nigeria

A. O. David, Ify L. Nwaogazie, J. C. Agunwamba

Journal of Engineering Research and Reports, Page 1-10
DOI: 10.9734/jerr/2019/v6i416956

The design of water resources engineering control structures is best achieved with adequate estimation of rainfall intensity over a particular catchment. To develop the rainfall intensity, duration and frequency (IDF) models, 25 year daily rainfall data were collected from Nigerian Meteorological Agency (NIMET) Abuja for Abeokuta. The annual maximum rainfall amounts with durations of 5, 10, 15, 20, 30, 45, 60, 90, 120, 180, 240, 300 and 420 minutes were extracted and subjected to frequency analysis using the Excel Optimization Solver wizard. Specific and general IDF models were developed for return periods of 2, 5, 10, 25, 50 and 100 years using the Gumbel Extreme Value Type -1 and Log Pearson Type -3 distributions. The Anderson-Darling goodness of fit test was used to ascertain the best fit probability distribution. The R2 values range from 0.973 – 0.993 and the Mean Squared Error, MSE from 84.49 – 134.56 for the Gumbel and 0.964 – 0.997 with MSE of 42.88 – 118.68 for Log Pearson Type -3 distribution, respectively. The probability distribution models are recommended for the prediction of rainfall intensities for Abeokuta metropolis.

Open Access Original Research Article

Wafer Tape Selection Analysis for Adhesion Problem Mitigation

Bryan Christian S. Bacquian, Frederick Ray I. Gomez

Journal of Engineering Research and Reports, Page 1-8
DOI: 10.9734/jerr/2019/v6i416958

Wafer passivation or the protective layer of the internal circuitry of the die plays a major role of providing protection and the isolation of electrical stability of the active circuit on the top area of the wafer. Passivation is normally a screen of an oxide layer on the surface of the silicon wafer or the carrier of internal circuitry of the die. Passivation is normally in the form of polyimide or a glass material. From the wafer structure, it is important to cover the active circuit to ensure no other noises will be induced to the wafer. Inclusion of the passivation layer will help maximize the functionality of the semiconductor device thus eliminating noises coming from the external sources.

As the integrated circuit (IC) package goes thinner, the requirement of having the active circuit or the die thinner is the main concern during the wafer preparation process. Wafer backgrinding or wafer thinning is the focal process involved to satisfy such requirement. Prior performing the wafer thinning process, the application of tape, normally in a form of polyolefin or polyvinyl chloride should be performed to eliminate contamination and protects the active layer of the wafer during the process. However, there should be enough adhesion between the wafer and the thinning tape itself. High adhesion strength may lead to adhesive remains or worst, passivation will be peeled off from the active layer of the wafer.

Adhesion to the passivation layer should be properly evaluated and monitored in such way that will eliminate adhesive remains during detaping process after wafer thinning. The effect of adhesion strength could be predicted by properly selecting thinning or protective tape to be used. Higher adhesion strength could be achieved but due to criticality of passivation to tape adhesion, ultra-violet (UV) process should be included to substantially decreased the adhesion. The importance of UV exposure is also discussed on this paper.

Open Access Review Article

Numerical Methods for Information Tracking of Noisy and Non-smooth Data in Large-scale Statistics

B. S. Avinash, T. Srisupattarawanit, H. Ostermeyer

Journal of Engineering Research and Reports, Page 1-16
DOI: 10.9734/jerr/2019/v6i416957

In our universe, there is a presence of random bit of disorder in every field that has to be contemplated and understood clearly. This random bit of disorder in a physical system is known as noise. Noise in the field of statistics can be defined as an additional meaningless information that cannot be clearly interpreted which is present in the entire dataset. In large-scale statistics, noisy data has an adverse effect on the results and it can lead to skewness in any data analysis process, if not properly understood or handled. The adverse effect on the results is mainly due to uncorrelated (zero autocorrelation) property of noise. This makes it completely unpredictable at any given point in time, hence thorough investigation and removal of noise plays a vital role in data analysis process. In the field of engineering, measurement of experimental data obtained by using scientific instruments consists of some values that are independent of the experimental setup. One of most widely technique is the optimization methods viz, gradient descent, conjugate gradient, Newton’s method etc. Most of these methods require the determination of derivative of a function specified by the dataset (using finite-difference approximation). If the noisy data is approximated using a specific finite difference method this results in the amplification of noise present in the data. In order to overcome the aforementioned problem of amplification of noise in the derivative of a function, various regularization methods are employed. The parameter that plays a vital role in these methods are termed as regularization parameter. One of the most important technique used in the field of regularization is known as total variation regularization. This review aimed at gathering the disperse literature on the current state of various noises and their regularization methods.