On matching property for groups and field extensions

In this paper we prove a sufficient condition for the existence of matchings in arbitrary groups and its linear analogue, which lead to some generalizations of the existing results in the theory of matchings in groups and central extensions of division rings. We introduce the notion of relative matchings between arrays of elements in groups and use this notion to study the behavior of matchable sets under group homomorphisms. We also present infinite families of prime numbers p such that ℤ/pℤ does not have the acyclic matching property. Finally, we introduce the linear version of acyclic matching property and show that purely transcendental field extensions satisfy this property

Removal of Cationic Surfactants from Aqueous Solutions by Modified Cotton as a Novel High Capacity and Low Cost Adsorbent

Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before release to the environment or delivery for public use. Using cotton-based adsorbent may be an effective technique to remove surfactants. In this study, the removal of cationic surfactants by modified cotton was investigated. N-Cetyl-N,N,N-trimethylammonium bromide (CTAB) was selected as a cationic surfactant for the experiments. The results revealed that the modified cotton has a high affinity toward the cationic surfactants. Experiments were conducted to examine the effects of applied adsorbent dosage, initial concentration of adsorbate, pH, temperature, salt concentration on the removal efficiency. By increasing the salt concentration, removal efficiency was decreased slightly. The temperature had an adverse effect on removal efficiency. The adsorption of the CTAB increases with increasing pH of the solution. A series of batch experiments were performed to determine the sorption isotherms of modified cotton. Surfactant equilibrium data fitted very well to the Langmuir model. The Langmuir model showed that the maximum adsorption was 909 mg/g which is higher than the capacity of other adsorbents reported until now. The pseudo first-, second- order and corresponding rate equation kinetic models were investigated. Adsorption complies with a pseudo-second-order rate equation

An empirical investigation on factors influencing customer loyalty and their relationships with quality of services: A case study of insurance firm

In this paper, we present an empirical investigation to study the effect of various factors influencing customer loyalty and quality of services on customer satisfaction and customer loyalty. The proposed study is implemented in one of Iranian insurance firms by choosing a sample of 171 randomly selected customers of this insurance firm. We use SERVQUAL standard questionnaire to measure customer satisfaction. The study examines three hypotheses associated with the proposed study using one-way t-student as well as path analysis, and the results have confirmed all three hypotheses. The study also uses Freedman test to rank the most important factors and detects that value was the most important issue followed by trust, customer satisfaction, empathy, value and resistance to change

Identifying productive zones of the Sarvak formation by integrating outputs of different classification methods

International audienceSarvak formation is the second major carbonate reservoir in Iran. There are several geological, petrophysical and geophysical investigations which have been carried out on this important reservoir. In this work, Sarvak is studied to find productive zones. At first, four different methods were used to identify producing intervals from well log data and well test results. Then, final zoning is generated by integrating outputs of these four methods. One of them is the conventional cutoff based method; the other three methods are based on flow equation, Bayesian and fuzzy theories. Thereafter, by considering the classification correctness rate of each classifier in each well and technique of majority voting, a unique zoning for Sarvak formation is presented. Based on the final zoning, the whole Sarvak interval is divided into seven zones. Three of them are classified as oil producing zones, two of them cannot be classified as conventionally producing zones, and the remaining two are water producing. Zone number 2 not only has the highest production rate, but also is the most homogeneous zone among the productive zones. The novelty of this research is using well test results in defining productive classes, which improves the certainty of classification in comparison with previous works that were based on core analysis and log data

Application of fuzzy classifier fusion in determining productive zones in oil wells

International audienceThis study is an application of data fusion techniques, especially fuzzy theory, in determining oil producing zones through four nearby wells, located on an oil field in south west of Iran. Two fusing techniques, used here are based on Bayesian and fuzzy theories. At first, two Bayesian classifiers are being constructed by training in two different wells; then a fuzzy operator, called Sugeno discrete integral, is used to fuse outputs of two mentioned Bayesian classifiers. Finally, it is concluded that using fuzzy classifier fusion improves not only certainty and confidence of decision making, but also generalization ability of determining productive zones