Linear-like properties arise naturally in the adaptive control setting

Classical discrete-time adaptive controllers typically provide asymptotic stabilization and tracking; usually the affect of the noise is at best bounded-input bounded-output. Recently we have shown that if you design a discrete-time adaptive controller in just the right way, then in a variety of situations you not only obtain exponential stability, but also a bounded gain on the noise in every p−norm, as well as a never-before-seen linear-like convolution bound on the input–output behavior. Quite surprisingly, the approach is very natural, and relies on the use of the unmodified, original projection algorithm to carry out parameter estimation; if the set of plant uncertainty is not convex, then a multi-estimator and switching are used. The goal of this paper is to provide an overview of the approach, discuss the results-to-date, and list some of the open problems.     

Development of a Hybrid Data Driven Model for Hydrological Estimation

High and low stremflow values forecasting is of great importance in field of water resources in order to mitigate the impacts of flood and drought. Most of water resources models deal with the problem of not being flexible for modeling maximum and minimum flows. To overcome that shortcoming, a combination of artificial neural network (ANN) models is developed in this study for monthly streamflow forecasting. A probabilistic neural network (PNN) is used to classify each of the input-output patterns and afterward, the classified data are forecasted using a modified multi-layer perceptron (MMLP). In addition, the performance of the MLP and generalized regression neural network (GRNN) in streamflow forecasting are investigated and compared to the proposed method. The findings indicate that the R² associated with the suggested model is 46 and 80% higher compared to MLP and GRNN models, respectively.     

Investigation and numerical analysis of strain distribution in the twist extrusion of pure aluminum

The effects of performing three twist extrusion passes on high purity aluminum samples were studied in this paper in regard to numerical analysis and experimental studies. The finite element analysis of the von-Mises stress and the equivalent plastic strain in the outer longitudinal and transverse cross-sections, which are parallel and normal to the billet axis respectively, was carried out. The simulation results showed that the end of the workpiece underwent more equivalent plastic strains in contrast to the head of the sample. Moreover, the corner regions experienced more strains than the center zone did. However, the heterogeneity in strain distribution in both longitudinal and transverse cross-sections decreased by performing the sequential twist extrusion passes. The experimental outcomes such as microstructure evolutions, microhardness and tensile tests validated the simulation results.     

An analytical model for production data analysis of under saturated oil reservoirs subjected to edge aquifer

Analysis of production data is an important method for estimating recoverable reserves and probable life of the reservoirs. Robust techniques for analysis of production data have been developed and widely used for many years. These methods range from the traditional Arps decline method to modern production data analysis. The most recent techniques are based on material balance time to account for variable operating conditions. In these methods, production rate and flowing bottom hole pressure must be known. A major limitation of many existing modern techniques is volumetric assumption of the reservoir.This paper presents a new model that accounts for non-volumetric effects of edge aquifers on production data analysis of single phase oil reservoirs by defining a new material balance time function. This new time function and material balance time help us to introduce flowing material balance (FMB) equations for such reservoirs. Validity of these equations is justified using analytical solutions. For development of analytical solutions, special simplifying assumptions are considered. To justify these assumptions, comparison is made using a commercial numerical reservoir simulator across some ranges of reservoir parameters.Furthermore, based on the validated FMB equations and obtained analytical flow equations, specific procedures are developed for parameter estimation of such reservoirs. The use of these procedures in estimation of oil in place and reservoir external radius is demonstrated using synthetic examples. On the basis of the considered assumptions, the proposed procedures cannot be applied to multi-phase flow conditions, reservoirs with other types of aquifer (such as bottom aquifer), and gas reservoirs.We also show that the given FMB equations are applicable for any irregularly shaped reservoir which is partially contacted with a non-cylindrical limited edge aquifer. For such reservoir geometries, numerical solution is used for justification. This is followed by introducing a simple equation for predicting average reservoir pressure.     

Biopower generation from mountain pine infested wood in Canada: An economical opportunity for greenhouse gas mitigation

Biomass is considered carbon neutral, and displacement of fossil fuel-based power by biomass-based power is one means to mitigate greenhouse gases. Large forest areas in British Columbia (BC), Canada, are infested by the mountain pine beetle (MPB). Dead wood from the infestation is expected to vastly exceed the ability of the pulp and lumber industry to utilize it; current estimates are that 200–600 million m³ of wood will remain unharvested over the next 20 years. Regions where the damaged wood is not harvested will experience loss of jobs in the forestry sector, increased risk of forest fire hazard, carbon emissions from burned or decaying wood, and uncertainty about timing of replanting since this usually occurs at harvest. This paper reports the results of a detailed preliminary techno-economic analysis of producing power from MPB killed wood. Power plant size and location are critical factors affecting overall power cost. Overall cost of power rises steeply at sizes below 300 MW net power output. By locating the power plant in an area of high infestation, transportation distances can be minimized. A 300 MW power plant would consume 64 million m³ of wood over a 20-year lifetime, and hence is a significant sink for otherwise unharvestable wood. Cost estimates are based on harvesting of whole dead trees with roadside chipping and transport to a central power plant located in either the Nazko or Quesnel regions of BC. A circulating fluidized bed boiler with a conventional steam cycle is a currently available technology demonstrated at 240 MW in Finland. The estimated power cost is $68 to $74 per MWh, which is competitive with other “green power” values in BC. Given recent values of export power in the Pacific Northwest, a 300 MW MPB power plant is viable with a carbon credit below $15 per tons of CO₂.     

MODIFICATION OF ASPHALT BY CHEMICAL TREATMENT WITH SULPHUR

The Theological properties of asphalt of different chemical compositions were assessed after treating them with sulphur at various reaction conditions. To correlate the observed alterations in the physical properties of the products with changes in the chemical composition, a study on model compounds was conducted to throw some light on this issue.     

Modelling the Bulk Cooling of Alfalfa Pellets

Cooling of alfalfa pellets after being made is one o f the unit operations in the pelleting of alfalfa. Using the thermal properties and drying diffusion coeficient together with other properties reported in refereed journals. a combined heat and mass transfer model was developed for the cooling of alfalfa pellets in deep beds. The model utilized the distributed heat and mass transfer equations to describe the temperature and moisture of the pellets. The distributed model interacts with the cooling air through a convective boundary condition for the temperature and a time-varying exponential surface condition for the moisture. Coupling o f the heat and mass transfer processes was carried out at the surface of the pellet using evaporative surface condition. The model was validated with field experimental data from a double-deck crossflow cooler. The simulated pellet and air temperatures were within 5⁰C of the collected field data while predicted moisture from the model was within 0.3% o f the experimental data.     

IMPROVED HEAT AND MASS TRANSFER MODELS TO PREDICT GRAIN QUALITY

This paper reviews a recent development in the heat and moisture transfer modeling for drying single layes of agricultural grains. A diffusion model with time-varying boundary condition predicts the complex shape of the drying curve well. A conduction model with evaporating boundary condition, when used with the Gamson correlation for convective heat transfer coefficient, accurately predicts experimental grain surface temperature. The new modewls were tested experimentally, drying wheat and barley in a thin-layer dryer useing 40 to 175 c air and the initial moisture ranging from 0.20 to 0.40 (decimal dry basis). It is shown that grain temperatures calculated by the conduction heat equation, when used in conjunction with a probit-type germination loss model, predict germination values different from those predicted by the lump heat equation.