Optically anisotropic fragments in a Western Canadian subbituminous coal

Large Isotropic and anisotropic, angular and rounded fragments of inertinite were found in a Canadian subbituminous coal (%R oil = 0.50). The istropic fragments included pyrofusinite, macrinite and pseudovitrinite with pre-oxidized, heat-treated fragments showing oxidation rims. The anisotropic fragments include the heat-treated residue of liptinite, e.g. resinite showing granular anisotropy, pyrolytic carbon and fragments of vitrinite showing basic anisotropy. The morphology of inertinite fragments is described and an attempt is made to correlate these particles with heat-affected coal macerals. The occurrence of pyrolytic carbon with a reflectance of 3.11% and of liptinite showing anisotropy in a coal matrix with a reflectance of 0.50% is unusual. It indicates the detrital nature of the pyrolytic carbon. The formation of isotropic and anisotropic inertinite was possibly due to a thermal event, perhaps a wood or swamp fire. The pseudovitrinite found in these coals may have been formed by heat-treatment of fossil oxidized vitrinite fragments. The anisotropic fragments in the coals (e.g. pyrolytic carbon and anisotropic vitrinite), are detrital and are grouped with inertodetrinite.     

Use of the dendograph for data processing in fuel science

In fuel science there is a need to present the relationships between the elements of a group of variables or a group of samples as tables of data. The dendrograph, a derivative of the dendogram, is a method used for general cluster analysis. It offers an improvement by providing an irregular spacing of the objects classified on the x axis. The mathematical basis of this method is described as unweighted pair group method of clustering.     

Coreless Fiber‐Based Whispering‐Gallery‐Mode Assisted Lasing from Colloidal Quantum Well Solids

Whispering gallery mode (WGM) resonators are shown to hold great promise to achieve high‐performance lasing using colloidal semiconductor nanocrystals (NCs) in solution phase. However, the low packing density of such colloidal gain media in the solution phase results in increased lasing thresholds and poor lasing stability in these WGM lasers. To address these issues, here optical gain in colloidal quantum wells (CQWs) is proposed and shown in the form of high‐density close‐packed solid films constructed around a coreless fiber incorporating the resulting whispering gallery modes to induce gain and waveguiding modes of the fiber to funnel and collect light. In this work, a practical method is presented to produce the first CQW‐WGM laser using an optical fiber as the WGM cavity platform operating at low thresholds of ≈188 µJ cm^?2 and ≈1.39 mJ cm^?2 under one‐ and two‐photon absorption pumped, respectively, accompanied with a record low waveguide loss coefficient of ≈7 cm^?1 and a high net modal gain coefficient of ≈485 cm^?1. The spectral characteristics of the proposed CQW‐WGM resonator are supported with a numerical model of full electromagnetic solution. This unique CQW‐WGM cavity architecture offers new opportunities to achieve simple high‐performance optical resonators for colloidal lasers.     

Conceptual feature generation for textual information using a conceptual network constructed from Wikipedia

A proper semantic representation of textual information underlies many natural language processing tasks. In this paper, a novel semantic annotator is presented to generate conceptual features for text documents. A comprehensive conceptual network is automatically constructed with the aid of Wikipedia that has been represented as a Markov chain. Furthermore, semantic annotator gets a fragment of natural language text and initiates a random walk to generate conceptual features that represent topical semantic of the input text. The generated conceptual features are applicable to many natural language processing tasks where the input is textual information and the output is a decision based on its context. Consequently, the effectiveness of the generated features is evaluated in the task of document clustering and classification. Empirical results demonstrate that representing text using conceptual features and considering the relations between concepts can significantly improve not only the bag of words representation but also other state‐of‐the‐art approaches.     

Active fuzzy modeling for estimating problems in hydrocarbon reservoirs

While active learning method (ALM) uses error as the learning parameter, selection of the validation data is still challenging. In this paper, to prevent form encountering with sample size problem, we applied an error-independent version of ALM that we call the active fuzzy modeling (AFM) with a distance threshold to model parameters of hydrocarbon reservoirs. In this paper, we demonstrate that measuring the generalization error is a vital factor in the process of ALM. Regression (R) and mean squared error (MSE) for estimating RHOB by AFM were 0.96 and 0.0032, respectively. On the other hand, R of 0.91, 0.89 and 0.92 and MSE of 0.0051, 0.0067 and 0.0047 for ANN, TS-FIS and NF, respectively, illustrate that AFM performs much better in comparison with conventional modeling approaches and produces more reliable results. Comparing the results of the presented method with ANN, TS-FIS and NF in aspect of rapidity, robustness, storage, complexity and acceptability in estimating RHOB reports the accuracy and high-performance behavior of AFM. This method is illustrated by an example of an oil field at NW Persian Gulf.     

Design of an all optical half-adder based on 2D photonic crystals

The present study was designed and simulated for an all optical half-adder, based on 2D photonic crystals. The proposed structure in this work contains a hexagonal lattice. The main advantages of the proposed designation can be highlighted as its small sizing as well as simplicity. Furthermore, the other improvement of this half-adder can be regarded as providing proper distinct space in output between “0” and “1” as logical states. This improvement reduces the error in the identification of logical states (i.e., 0 and 1) at output. Because of the high photonic band gap for transverse electric (TE) polarization, the TE mode calculations are done to analyze the defected lines of light. The logical values of “0” and “1” were defined according to the amount of electrical field.     

Low temperature dynamic mechanical response of porous Vycor glass as a function of moisture content

An experimental apparatus designed to measure automatically the internal friction and the elastic modulus of solid beams based on the resonance principle is described. The internal friction and the elastic modulus of porous Vycor glass beams containing different amounts of water has been measured as a function of temperature from 25 to –160° C. Two transitions are evident in the response: the capillary transition (–40 to 0° C) caused by freezing of capillary condensed water, and the adsorbate transition (centred around –85° C) associated with a gradual solidification of water adsorbed near the pore surfaces. More than half of all the water in a saturated beam freezes during the capillary transition, but this ice contributes only modestly to the elastic modulus of the beam which implies that there is little contact between the ice and the glass matrix. Further cooling into the adsorbate transition temperature range is believed to cause a gradual solidification of the adsorbed water, until at very low temperatures the adsorbed layer is glassy and effectively cements the glass matrix and the ice together resulting in a large increase in the elastic modulus of the beam.     

Experimental and CFD analysis of photocatalytic gas phase vinyl chloride (VC) oxidation

Photocatalytic destruction of gas phase vinyl chloride (VC) was examined using experimental and computational fluid dynamics (CFD) approaches. Experimental work involved using a differential photoreactor for determining kinetics of oxidation and an annular flow photoreactor for overall removal investigations as well as comparison with CFD models. The kinetic data obtained from differential photoreactor were used to model and predict the performance of the annular photoreactor using CFD. The photocatalytic oxidation of VC followed first order kinetics for inlet concentrations up to about and CFD was able to predict the removal of VC in the system. Both experimental and CFD modeling showed the removal of VC in the system increased with increasing the VC loading rate. CFD analysis of the photoreactor also provided insight into the detailed concentration gradient of VC within the reactor. The modeling results indicated significant radial VC concentration gradient and non-uniform flow distributions in the annular photoreactor. This non-uniform flow distribution, in turn, resulted in short circuiting of the VC contaminated gas and may have resulted in less than optimum removal efficiency for VC in the annular reactor over the entire range of inlet VC concentrations. Overall, the information provided by CFD modeling and simulation showed to be valuable for reactor design modification and for improving the reactor performance.     

Friction and wear characteristics of steel on rock under water and oil based lubricated sliding conditions

Abstract

In recent years, drilling extended reach wells have become more and more common in the petroleum industry to optimise the oil and gas production. Extended reach wells are defined as wells that have two times more horizontal step out than true vertical depth. High friction (frictional torque) and drag are two of the mechanical limiting factors while drilling longer horizontal wellbores. There are numerous methods and tools developed to lower the drillstring friction. Drilling non-circular wellbores is a new concept with potential to minimise the mechanical friction by reducing drillstring and sidewalls contact area. However, this will cause an increase of contact pressure owing to the reduced contact area between drillstring and the formation. This article presents results obtained from an experimental study pertaining to the friction behaviour using a pin on disc set-up with steel pin and granite disc in the presence of water and oil based lubricants. These tests have been designed to represent frictional contact conditions between a rotating steel drillstring and the wellbore wall at different contact pressures. Test results show that the friction coefficient decreases with an increase of contact pressure in wet condition for both water and oil based lubricants. It is also observed that the friction factor increased by adding sand and phyllite particles to the water based lubricant. Considering the wear scars, the friction coefficient shows reduction with increased contact pressure in all tests with and without particles for both water and oil based lubricants.     

A new approach to modified regularized long wave equation

In this paper, a homotopy analysis method employed to obtain approximate numerical solution of the modified regularized long wave (MRLW) equation with some specified initial conditions. The results show that the method converges rapidly and approximates the exact solution very accurately using only few iterates of the recursive scheme. The proposed technique solves the nonlinear problems without using Adomian polynomials and He’s polynomials, which can be considered as a clear advantage of this new algorithm over decomposition and the homotopy perturbation method. Numerical results are presented graphically, and tabular form reveals that the homotopy analysis method is an effective and convenient method to solve MRLW equation.