Carbon nanostructures via adding to a polymer matrix, while improving the electrical, mechanical and optical properties of the nanocomposites, are widely used in the industry, medicine, and agriculture. The authors presented several investigations on a new type of gamma dosimeter based on the polymer-carbon nanostructures nanocomposite. In this research, the electrical percolation threshold of the Polystyrene-Graphene Oxide nanocomposite (PS/GO) was simulated using the finite element method in different weight percentages. Then, at the experimental phase, various nanocomposites were fabricated in different weight percentages of 0. 05, 0. 1, 0. 5, 1, 2, 3, 5 and 8 via the mixed-solution process. The electrical conductivities of the samples were measured at the room temperature. Finally, the electrical conductivities of the nanocomposites were compared using the FEM simulation and the experimental results, which were estimated as 2. 5wt%. The results of this study showed that the finite element method in accordance with the experimental results is a powerful tool to determine the electrical properties of the polymer nanocomposites considering the dosimetric approaches.

The cyclicvoltammetry method was utilized for the determination of percolation threshold of electroactivity of polyvinylchloride (PVC) and doped polyaniline through sulphosalicylic, acid (SSA) blend. The blends were prepared from N-methylpyrrolidone (NMP) solutions and PVC/PANI-SSA blend with weight fractions from 0.1 to 0.006 of polyaniline. The films from the blends were provided by. casting the above polymer solutions on a GC electrode. Voltammograms were recorded by using a one-compartment cell fitted with a GC as working electrode, Pt as auxiliary electrode and SCE as reference electrode, in 1M perchloric acid electrolyte solution. The obtained results from cyclicvoltammetry showed that PANI-SSA/PVC on and above 0.008 percent weight from polyaniline is electroactive.

Simultaneous capillary dominated displacement of the wetting and non-wetting phases are processes of interest in many disciplines including modeling of the penetration of polluting liquids in hydrology or the secondary migration in petroleum reservoir engineering. Percolation models and in particular invasion percolation is well suited to characterize the slow immiscible displacement of two fluids when both the gravity and viscous effects are negligible. In particular, the characteristic of the percolating cluster and the other important percolation properties at the breakthrough can be inferred. However, with the inclusion of the gravity forces, the behavior may change. For example, as the magnitudes of the gravity forces are comparable to the capillary forces, we have observed a transition in the structure of the interface (i.e. invasion front) depending on the dimensionless Bond number (i.e. ratio of gravity to capillary forces).We have taken a numerical study of the displacement of two immiscible fluids in the presence of the gravity force in a network of random pores. The main contribution is to investigate the effect of heterogeneity by considering various throat size distributions. We consider the injection to take place from one side of the system and displace the displaced fluid from the other side. The condition of the stability or instability of the front (or interface) is observed to be dependent on the dimensionless bond number as well as the heterogeneity of the system. 

Introduction: Cochlear dead zones are defined as areas where the inner hair cells have been destroyed.Thresholds on the audiograms show the integrity of those parts of the ear that are tested. Care must be taken in interpretating audiograms. Thanks to the advances in understanding of cochlear functions, it is now possible to spot false responses that come from dead zones of the cochlea. Recently, cochlear dead regions have been detected via TEN (Threshold Equalizing Noise) test in which ipsilateral broadband noise and threshold shifting are used.Materials and Methods: A review of the literature on the subject of dead zones published from 1993 to 2003 was performed using Pubmed, Ebsco, Science Direct, Google Scholar Thieme ProQuest databases and library sources. key word: were "cochlear dead zone", "traveling wave", "ten (threshold equalizing noise) test", "ipsilateral noise" and "real-ear measurement for hearing aids prescription".Conclusion: Hearing aids fitting process for patients with severe and sloping sensory neural hearing loss must be noted specially by amplifying active zone and avoiding amplification for dead region i.e., offering amplification to the transition frequencies that have better hearing than others, those among the fine regions and the dead zones. Dead zone detection may help in hearing aids fitting and fine tuning.

Water flooding is a well known secondary mechanism for improving oil recovery. Conventional approach to evaluate the performance of a water flooding process (e.g. breakthrough and post breakthrough behavior) is to establish a reliable geological reservoir model, upscale it, and then perform flow simulations. To evaluate the uncertainty in the breakthrough time or post breakthrough behavior, this procedure has to be repeated for many realizations of the geological model, which takes many hours of CPU time. Moreover, during the early stage of reservoir life, when data is scare, breakthrough and post breakthrough time behavior prediction are usually based on analogues or rules of thumb. Alternative statistical approach is to use percolation theory to predict breakthrough and post breakthrough bahavior. The main contribution is to evaluate the applicability of the existing scaling laws of the breakthrough time by the numerical flow simulation results using the Burgan formation dataset of Norouz offshore oilfield in the south of Iran. Moreover, we extend the scaling to the post breakthrough behavior. There is good agreement between the predictions from the percolation based expressions and the numerical simulation results. Moreover, the prediction from the scaling law took a fraction of a second of CPU times (as it only needs some algebraic calculations) compared with many hours required for the conventional numerical simulations.

Most traditional soil improvement methods are time consuming, expensive, require heavy machinery and are environmentally detrimental. As a potentially more environmentally favorable ground improvement method, biomediated soil improvement offers an alternative to traditional soil improvement techniques. This method is based on microbial precipitation of calcium carbonate. The role of bacteria is producing urease enzyme to catalyzing hydrolysis of urea. In the presence of calcium ions, the produced carbonate ions in hydrolysis of urea, react with the calcium ions and calcium carbonate sediment was formed. This paper investigates the applicability of biomediated soil improvement in modification of dry loose sand by surface percolation. To evaluate the success of treatment, a series of laboratory experiments was conducted, including, shear wave velocity, unconfined compressive strength, Brazilian tensile strength, calcium carbonate content and etc. The study has revealed that biomediated improvement technique caused the improvement of strength as a result of the cementation of sand particles. Furthermore, surface percolation method has the potential of cementation and stabilization of loose sand with desirable depth. Increase in strength and calcium carbonate content decreases with increase of depth. Results also shows that increase of strength due to bio-improvement depends not only to calcium carbonate content but also to its spatial distribution in pores and particle-to-particle binding numbers.

In this paper, we introduce a percolation model consisting of random walk movements on a lattice. Random walk not only has local movements, but also has non-local movements on the lattice. We obtain the percolation transitions and critical exponents for this model. Our findings show that the percolation threshold decreases with increasing non-local movements. Also, we find the universal scaling functions for the size of the largest gap and biggest cluster by the extreme value theory.