Corrosion of steel reinforcement in concrete of different compressive strengths

Corrosion of steel bars embedded in concrete having compressive strengths of 20, 30 and 46 MPa was investigated. Reinforced concrete specimens were immersed in a 3% NaCl solution by weight for 1, 7 and 15 days. In order to accelerate the chemical reactions, an external current of 0.4 A was applied using portable power supply. Corrosion rate was measured by retrieving electrochemical information of polarization technique. Pull-out tests of reinforced concrete specimens were then conducted to assess the corroded steel/concrete bond characteristics.Experimental results showed that corrosion rate of steel bars and bond strength between corroded steel/concrete were dependent on concrete strength and accelerated corrosion period. As concrete strength increased from 20 to 46 MPa, corrosion rate of embedded steel decreased. First day of corrosion acceleration caused a slight increase in steel/concrete bond strength, whereas sever corrosion after 7 and 15 days of corrosion acceleration significantly reduced steel/concrete bond strength. Visual and metallographic observation of steel bars removed from concrete samples after testing revealed that the severity of corrosion reactions and reduction of steel bar diameter increased as the corrosion acceleration period increased. Presence of localized corrosion pits as well as severe corrosion grooves of steel bars was confirmed after 7 and 15 days of corrosion acceleration, respectively.     

Studies on the whey utilization in cheese making Part 2. Ras Cheese

Ras cheese was made from fresh milk, whey was collected and dried skimmilk was used to prepare a reconstituted milk with 20% total solids. Ras cheese was made from it and that was repeated for another three times. The addition of whey was benificial in reducing the time necessary for raising the acidity of milk to make it suitable for rennet action, up to its half. The time necessary to make it suitable for whey removal was reduced up to its half also. Consequently the time required for pressing was 8 h only, instead of 16 h. Generally, it is considered to be a better way in using the whey in Ras cheese making. In addition, it produced a good and acceptable cheese.     

Asymptotic Distribution of Bayes Estimators in Censored Type-I Samples From A Mixed Exponential Population

Bayes estimators in censored type-I samples, from a mixed exponential population are considered. Their large sample properties are examined by simulation. A log-normal distribution can explain adequately the asymptotic behaviour of Bayes estimators of the parameters.     

A Branch-and-Bound Algorithm for Flow Shop Scheduling Problems

This article is concerned with the solution of the flow shop scheduling problem in which all jobs have the same machine ordering. A branch-and-bound algorithm is developed for finding the sequence of J jobs to be processed on M machines which minimizes the schedule time. Thib algorithm consists of branching and bounding processes, but without the backtracking process which guarantees optimality. The procedure employed is that in constructing a subset of feasible sequences, a node representing a partial sequence is branched. Selection of the node depends on the lower-bound concept as a decision rule. This lower bound is based on resolving the conflict of jobs on the last machine. By using this algorithm, the number of explored nodes is considerably reduced and, hence, the computational effort involved in obtaining an optimal or near-optimal solution is decreased. High quality of solutions is obtained. Computationally, this algorithm extends the size of problems that can reasonably be solved.     

Effects of benzotriazole on the corrosion of Cu10Ni alloy in sulfide-polluted salt water

Benzotriazole (BTAH) is shown to inhibit the corrosion of the Cu10Ni alloy in salt water polluted by sulfide ions. The presence of sulfide ions (at 2 ppm) decreases the inhibiting efficiency of BTAH against the corrosion of Cu10Ni alloy. This is illustrated by measurements of the integral weight loss of the alloy, its average corrosion rate and the weight of the corrosion product film over exposure times of up to 840 h. The results are interpreted in terms of competitive adsorption of the protective BTAH and the corrosion promoting sulfide ions on the alloy surface. In the presence of high concentration of BTAH, X-ray diffraction measurements revealed the absence of copper sulfide in the corrosion product film while metallographic examination revealed a much lower extent of corrosion.     

Rank aggregation methods comparison: A case for triage prioritization

This paper seeks to test and to determine a suitable aggregation method to represent a set of rankings made by individual decision makers (DMs). A case study for triage prioritization is used to test the aggregation methods. The triage is a decision-making process with which patients are prioritized according to their medical condition and chance of survival on arrival at the emergency department (ED). There is a lot of subjective decision-making in the process which leads to discrepancies among nurses. Four rank aggregation methods are applied to the prioritization data and then an expert evaluates the results and judges them on practicality and acceptability. The proposed recommendation for preference aggregation is the method of the estimation of utility intervals. Expert opinion is highly valued in a decision-making environment such as this, where experience and intuition are key to successful job performance and outcomes.     

Application of flower pollination algorithm in load frequency control of multi-area interconnected power system with nonlinearity

This work presents an application of bio-inspired flower pollination algorithm (FPA) for tuning proportional–integral–derivative (PID) controller in load frequency control (LFC) of multi-area interconnected power system. The investigated power system comprises of three equal thermal power systems with appropriate PID controller. The controller gain [proportional gain (K _p), integral gain (K _i) and derivative gain (K _d)] values are tuned by using the FPA algorithm with one percent step load perturbation in area 1 (1 % SLP). The integral square error (ISE) is considered the objective function for the FPA. The supremacy performance of proposed algorithm for optimized PID controller is proved by comparing the results with genetic algorithm (GA) and particle swarm optimization (PSO)-based PID controller under the same investigated power system. In addition, the controller robustness is studied by considering appropriate generate rate constraint with nonlinearity in all areas. The result cumulative performance comparisons established that FPA-PID controller exhibit better performance compared to performances of GA-PID and PSO-PID controller-based power system with and without nonlinearity effect.

     

A hybrid shape-based image clustering using time-series analysis

Clustering of different shapes of the same object has an inordinate impact on various domains, including biometrics, medical science, biomedical signal analysis, and forecasting, for the analysis of huge volume of data into different groups. In this work, we present a novel shape-based image clustering approach using time-series analysis, to guarantee the robustness over the conventional clustering techniques. To evaluate the performance of the proposed procedure, we employed a dataset consists of various real-world irregular shaped objects. The shapes of different objects are first extracted from the entire dataset based on similar pattern using mean structural similarity index. Furthermore, we performed radical scan on the extracted shapes for converting them to one-dimensional (1D) time-series data. Finally, the time series are clustered to form subgroups using hierarchical divisive clustering approach with average linkage, and Pearson as distance metrics. A comparative study with other conventional distance metrices was also conducted. The results established the superiority of using Pearson correlation measure, which provided the maximum F1-score with exact number of shapes under a sub-cluster, while the corresponding outcomes of other approaches results in a poor and inappropriate clustering.