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.     

The Influence of Office Furniture,Workstation Layouts,Diffuser Types and Location on Indoor Air Quality and Thermal Comfort Conditions at Workstations

Abstract Many factors affect the airflow patterns, contaminant removal efficiency and the indoor air quality at individual workstations in office buildings. The effects of office furniture design and workstation layouts on ventilation performance, contaminant removal efficiency and thermal comfort conditions at workstations were studied. The range of furniture configurations and environmental parameters investigated included: 1) partition heights, 2) partition gap size, 3) diffuser types, 4) supply air diffuser location relative to the workstation, 5) return air grill location relative to the workstation, 6) heat source locations, 7) presence of furniture, 8) supply air temperatures, 9) adjacent workstations, 10) contaminant source locations, 11) supply air flow rates, and 12) outdoor air flow rates. The tracer gas technique was used to study experimentally the relative impact of these parameters on the air distribution and ventilation performance, as well as contaminant removal efficiency. Thermal environmental parameters such as air velocity and temperature were monitored at several locations to characterize the impact of these parameters on the thermal comfort conditions. The results showed that the outdoor air flow rate had a significant influence on the mean age of air. The air distributions at all the workstations were good even when the supply air flow rate was relatively low (i.e 5 L/s). At the same time, most of the parameters tested had a significant influence on contaminant removal efficiency when there was a contaminant source present somewhere in the office.     

A genetic algorithm for solving no-wait flexible flow lines with due window and job rejection

This paper addresses a no-wait multi-stage flexible flow shop problem. There are n jobs to complete in a predetermined due window; hence, some jobs may be rejected. A mixed integer linear programming model with the objective of maximizing the total profit gained from scheduled jobs is introduced. Since the problem is NP-hard and difficult to find an optimal solution in a reasonable computational time, an efficient genetic algorithm is presented as the solution procedure. A heuristic mechanism is proposed to use in each generation of the genetic algorithms to assure the feasibility and superior quality of the obtained solutions. Computational results show that the presented approach performs considerably in terms of both quality of solutions and required runtimes.     

Assessing the performance of air cleaning devices – A full-scale test method

Activated carbon filters have been used for purification of air and water in industrial applications. However, these technologies have not been applied to the non-industrial built environment in general and there is no standard to quantify or to classify the performance of these systems for in-duct mechanical system application. The development of a standard test procedure is a very timely effort, since it would create a benchmark for evaluating the contaminant reduction of these systems. A full-scale test facility was designed and constructed to investigate the removal effectiveness of commercial gas-phase air cleaning devices. The test rig was verified by conducting the system pre-qualification tests. These series of tests were designed to quantitatively verify the reliability of the test rig for gas filter application. These tests include air tightness, velocity uniformity, uniform dispersion of challenge contaminants, temperature and humidity control. This paper first describes the experimental set-up for testing of in-duct air cleaner systems and its verification, and then presents the experimental results of four different kinds of commercial gaseous filters.     

Convective heat transfer prediction in large rectangular cross-sectional area Earth-to-Air Heat Exchangers

An Earth-to-Air Heat Exchanger (ETAHE) uses the ground's thermal storage capacity to dampen ambient air temperature oscillations by delivering the outdoor air to the indoors through a horizontally buried duct. With their lower airflow resistance, large cross-sectional area ETAHEs have been found to be more energy efficient than the conventional small ones, especially when integrated in hybrid ventilation systems. However, the lack of available methods for determining the heat convection at the duct surfaces has made accurate energy simulation and proper system design overly difficult. In this study, numerical experiments using computational fluid dynamics (CFD) were conducted to investigate the airflow and thermal behavior in the large ducts. A two-layer turbulence model was used to ensure accuracy in resolving the flow information in the near-wall region, which is critical for predicting accurate heat convection. The modeling method was verified by comparing its results with measurements from literature. Parametric studies were conducted to identify the influential design and operation variables for the heat convection. Thirty numerical experimental setups designed with the Latin Hypercube Sampling method were simulated to prepare a database with six design parameters as the simulation inputs and average Nusselt numbers over the duct ceiling, wall, and floor as the outputs. Based on the database an artificial neural network (ANN) model was trained to build a mathematical relation between the design variables and the Nusselt numbers. The developed ANN model showed very accurate prediction when compared with test data.     

Stress analysis of a finite wedge weakened by cavities

The solution of a Volterra-type screw dislocation in an isotropic wedge with finite radius and various boundary conditions is obtained by means of the image method. The solution is utilized to formulate integral equations for the finite wedge weakened by multiple cavities. The integral equations are of the Cauchy singular kind and are solved numerically to determine hoop stress on the cavities.     

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.     

Overland Water Flow and Solute Transport: Model Development and Field-Data Analysis

The application of plant nutrients with irrigation water is an efficient and cost-effective method for fertilizer application to enhance crop production and reduce or eliminate potential environmental problems related to conventional application methods. In this study, a combined overland water flow and solute transport model for analysis and management of surface fertigation/chemigation is presented. Water flow is predicted with the well-known Saint-Venant’s equations using a control volume of moving cells, while solute transport is modeled with the advection-dispersion equation. The 1D transport equation was solved using a Crank-Nicholson finite-difference scheme. Four, large-scale, field experiments were conducted on blocked-end and free draining furrows to calibrate and verify the proposed model. The results showed that application of solute during the entire irrigation event, or during the second half of the irrigation for blocked end conditions with appropriate inflow rates, produced higher solute uniformity than application of solute during the first half of the irrigation event. Measured fertilizer distribution uniformity of the low quarter ranged from 21 to 76% while fertilizer distribution uniformity of the low half values varied between 62 to 87%. The model was subsequently applied to the experimental data; results showed good agreement with all field data. Water balance errors for the different experiments varied from 0.004 to 1.8%, whereas fertilizer mass balance errors ranged from 1.2 to 3.6%. A sensitivity analysis was also performed to assess the effects of longitudinal dispersivity parameter on overland solute concentrations. A value of 10 cm for dispersivity provided a reasonable fit to the experimental data.