Oil reservoir waterflooding efficiency evaluation method

The effective hydrocarbon field development requires a well-developed waterflooding strategy with surveillance plan for continuous efficiency monitoring. The modified capacitance resistance model (CRM) is proposed to monitor the efficiency of oil field waterflood. The model outcomes give and understanding of flooding response. Forties field data was used to test and present the waterflood performance based on proposed modified CRM model.     

Effect of poly‐glutamate on uptake efficiency and cytotoxicity of cell penetrating peptides

Cell penetrating peptides (CPPs) were developed as vehicles for efficient delivery of various molecules. An ideal CPP‐peptide should not display any toxicity against cancer cells as well as healthy cells and efficiently enter into the cell. Because of the cationic nature and the intrinsic vector capabilities, these peptides can cause cytotoxicity. One of the possible reasons for toxicity of CPPs is direct translocation and consequently, pore formation on the plasma membrane. In this study it was demonstrated that interaction of poly‐glutamate with CPP considerably reduced their cytotoxicity in A549 cell. This strategy could be useful for efficient drug delivery mediated by CPP.Inspec keywords: cellular biophysics, polymers, drug delivery systems, biomedical materials, toxicology, molecular biophysicsOther keywords: drug delivery, A549 cell, plasma membrane, pore formation, cancer cells, poly‐glutamate, cytotoxicity, uptake efficiency, cell penetrating peptides     

Preparation of SAPO-34 catalyst and presentation of a kinetic model for methanol to olefin process (MTO)

Conversion of methanol to light olefins (MTO) using acidic SAPO-34 molecular-sieve as the reaction catalyst was studied in a differential fixed bed reactor within the temperature range of 375-425 °C and under 4 bar pressure. The importance of MTO process is due to the increasing demand for light olefins in recent years. SAPO-34 was synthesized by hydrothermal method, applying morpholine as the template. The latter compound was then changed into protonated form by ion exchange method with ammonium chloride at 80 °C. A simple stoichiometric scheme has been presented for MTO. In addition a mechanism for this process based on Langmuir-Hinshelwood formulation has been put forward and the kinetic parameters have been evaluated as functions of temperature.     

Effects of chitosan and zirconia on setting time,mechanical strength,and bioactivity of calcium silicate‐based cement

In this research, we aimed at improving the setting properties and biocompatibility of the mineral trioxide aggregate‐like cements while maintaining the main chemical formula. Consequently, chitosan and zirconium oxide were added to the cement instead of bismuth oxide to improve the mechanical behavior, limit the possible toxicity, and enhance the bioactivity of the cements. Adding zirconia resulted in a shorter setting time and adding chitosan contributed to the setting time, mechanical strength, and biocompatibility at the same time. Thus, cements containing both chitosan and zirconia had the shortest setting time, highest compressive strength, and apatite‐forming ability.     

Permutation flowshops with transportation times: mathematical models and solution methods

This paper deals with permutation flowshops with considering transportation times of carrying semi-finished jobs from a machine to another one. The transportation between machines can be done using two types of transportation systems: multi-transporter and single-transporter systems. We formulate the problem with both systems as six different mixed integer linear programs. We also provide solution methods including heuristics and metaheuristics in order to solve large-sized problems. The heuristics are the adaptations of well-known heuristics and the proposed metaheuristics are based on artificial immune systems incorporating an effective local search heuristic and simulated annealing. A comprehensive experiment is conducted to compare and evaluate the performance of the models as well as the algorithms. All the results show the effectiveness of the proposed models and algorithms.     

On Modified Successive Sampling Based Control Charting Schemes

The presence of variation cannot be avoided in different kinds of manufacturing and non‐manufacturing processes. A better understanding of the causes of variability in any process is necessary to improve the process. Control chart is a very frequently used tool for checking whether the process parameters are stable or not. The current study devises a sampling technique, named as modified successive sampling scheme, that is not only cost‐effective but also efficient as compared with the simple random sampling scheme. A number of Shewhart‐type control charts are proposed based on the said sampling scheme, and average run length is used as a performance indicator. Based on the average run length values, all the proposed charts are compared with existing Shewhart control chart for both positive and negative shifts in the process. Finally, the new proposals are applied to a real dataset where the variable of interest is an inner diameter of automobile engine piston rings made of steel. Copyright © 2015 John Wiley & Sons, Ltd.     

An Efficient Shewhart‐Type Control Chart to Monitor Moderate Size Shifts in the Process Mean in Phase II

According to Shewhart, control charts are not very sensitive to small and moderate size process shifts that is why those are less likely to be effective in Phase II. So to monitor small or moderate size process shifts in Phase II, cumulative sum (CUSUM) and exponentially weighted moving average (EWMA) control charts are considered as alternate of Shewhart control charts. In this paper, a Shewhart‐type control chart is proposed by using difference‐in‐difference estimator in order to detect moderate size shifts in process mean in Phase II. The performance of the proposed control chart is studied for known and unknown cases separately through a detailed simulation study. For the unknown case, instead of using reference samples of small sizes, large size reference sample(s) is used as we can see in some of nonparametric control chart articles. In an illustrative example, the proposed control charts are constructed for both known and unknown cases along with Shewhart ‐chart, classical EWMA, and CUSUM control charts. In this application, the proposed chart is found comprehensively better than not only Shewhart ‐chart but also EWMA and CUSUM control charts. By comparing average run length, the proposed control chart is found always better than Shewhart ‐chart and in general better than classical EWMA and CUSUM control charts when we have relatively higher values of correlation coefficients and detection of the moderate shifts in the process mean is concerned. Copyright © 2015 John Wiley & Sons, Ltd.     

Condition based maintenance in the context of opportunistic maintenance

Condition based maintenance (CBM) uses the operating condition of a component to predict a failure event. Compared to age based replacement (ABR), CBM usually results in higher availability and lower maintenance costs, since it tries to prevent unplanned downtime and avoid unnecessary preventive maintenance activities for a component. However, the superiority of CBM remains unclear in multi‐component systems, in which opportunistic maintenance strategies can be applied. Opportunistic maintenance aims to group maintenance activities of two or more components in order to reduce maintenance costs. In a serial system, this may also result in less downtime of the production line. The aim of this paper is to examine the impact of opportunistic maintenance on the effectiveness of CBM. We simulate a small system consisting of three components in series and vary the number of components under a CBM policy, the length of the opportunistic maintenance zone, the cost benefits of grouping maintenance activities, and the chance of a failure occurrence within a preventive maintenance (PM) interval. The results show that within the current experimental settings, CBM remains cost effective in the multi‐component serial system, but is less effective than ABR in grouping maintenance activities. When the chance of failure is small and the length of the opportunistic maintenance zone is large, ABR may even be a better option if line productivity is important.