WELL TEST MODEL IDENTIFICATION BY ARTIFICIAL NEURAL NETWORKS

ABSTRACT

The aim of this research is to investigate the performance of artificial neural networks computing technology, to identify preliminary well test interpretation model based on derivative plot. The approach is based on training the neural network simulator uses back-propagation as the learning algorithm for a predefined range of analytically generated well test response. The trained network is then requested to identify the well test identification model for test data, which is not used during training sessions. For creation of training examples, an analytical response generator is implemented which is capable of producing responses of various models. Both the neural network simulator and the analytical response generator is enfolded into a single package which is capable of producing diagnosis plots, transferring data and filtering the input pattern. Unlike the ones presented in literature the package utilises a distributed modular structure, by which saturation possibility of the neural network is reduced considerably. Moreover, the distributed structure allows the training sequence to be initiated on different computers, thus reducing the training time up to sixteen folds. The package is verified with several examples either analytically generated or taken from literature.     

Homogenized tensile and bending properties of plain weave single‐Ply E‐glass/epoxy

This study empirically, numerically, and analytically analyzes the tensile and bending behavior of a plain weave single‐ply E‐glass/epoxy composite. In the empirical part of the study, tensile and simple bending experiments are conducted. Finite element method is used in the modeling part of the numerical study. Transverse and longitudinal fibers of the plain woven composite are modeled in one and three dimensions by using the ABAQUS software. Finally, mixture ratio approach and composite beam approach are considered in the analytical part of the study. Elastic modulus, Poisson's ratio, bending stiffness, and critical bending radius are obtained experimentally and are compared with the results of the finite element analyses and the results of the analytical study where applicable. The results closest to the empirically obtained ones are obtained by three‐dimensional (3D) finite elements analysis. Moreover, the mechanical characteristics obtained by the composite beam approach used in the analytical study are also very close to the values obtained by 3D finite elements analysis. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Cooking quality and sensorial properties of noodle supplemented with oat flour

Effects of oat flour addition (10, 20, 30, and 40%) on the quality characteristics of noodle were investigated. Noodles were evaluated in terms of cooking quality, color, chemical, and sensory properties. As oat flour level increased, protein, crude fat, ash, Mn, Fe, Zn, and Mg contents of noodles increased. Oat flour caused increases in cooking loss of noodles. Sensory and cooking characteristics of noodles were negatively effected when oat flour level was increased compared with the control. Noodle with 10% oat flour received the highest sensory scores in all noodle samples containing oat flour. Overall acceptability scores of control and in only the noodle with 10% oat flour were found statistically (p<0.05) similar. Especially, the usage of 10% oat flour in noodle formulation gave satisfactory results in terms of acceptability.     

Ceramic Top Coats of Plasma-Sprayed Thermal Barrier Coatings: Materials,Processes, and Properties

The ceramic top coat has a major influence on the performance of the thermal barrier coating systems (TBCs). Yttria-partially-stabilized zirconia (YSZ) is the top coat material frequently used, and the major deposition processes of the YSZ top coat are atmospheric plasma spraying and electron beam physical vapor deposition. Recently, also new thermal spray processes such as suspension plasma spraying or plasma spray-physical vapor deposition have been intensively investigated for TBC top coat deposition. These new processes and particularly the different coating microstructures that can be deposited with them will be reviewed in this article. Furthermore, the properties and the intrinsic–extrinsic degradation mechanisms of the YSZ will be discussed. Following the TBC deposition processes and standard YSZ material, alternative ceramic materials such as perovskites and hexaaluminates will be summarized, while properties of pyrochlores with regard to their crystal structure will be discussed more in detail. The merits of the pyrochlores such as good CMAS resistance as well as their weaknesses, e.g., low fracture toughness, processability issues, will be outlined.     

3D Analyses of the Stability Loss of the Circular Solid Cylinder Made from Viscoelastic Composite Material

The 3D approach was employed for investigations of the stability loss of the solid circular cylinder made from viscoelastic composite material. This approach is based on investigations of the evolution of the initial infinitesimal imperfections of the cylinder within the scope of 3D geometrically nonlinear field equations of the theory of viscoelasticity for anisotropic bodies. The numerical results of the critical forces and critical time are presented and discussed. To illustrate the importance of the results obtained using the 3D approach, these results are compared with the corresponding ones obtained by employing various approximate beam theories. The viscoelasticity properties of the cylinder's material are described by the fractional-exponential operator. The numerical results and their discussion are presented for the case where the cylinder is made of a uni-directional fibrous viscoelastic composite material. In particular, it is established that the difference between the critical times obtained by employing 3D and third order refined beam theories becomes more non-negligible if the values of the external compressive force are close to the critical compressive force which is obtained at t = � (t denotes a time).     

Electrical and structural characterization of PLD grown CeO2–HfO2 laminated high-k gate dielectrics

The electrical and physical properties of CeO₂–HfO₂ nanolaminates deposited by pulsed laser deposition (PLD) are investigated. The properties of the nanolaminates are compared with binary CeO₂ and HfO₂ thin films. Layers were deposited using CeO₂ and HfO₂ targets at substrate temperatures between 220 and 620 °C in 10 Pa Ar+H₂ or O₂. In situ post deposition anneal (PDA) was achieved by controlled cooling down to room temperature with . Nanolaminates starting with CeO₂ show lower EOT and leakage compared to layers starting with HfO₂. TEM and XRD analyses showed thickness-dependent crystallinity of the layers, varying from amorphous to highly oriented polycrystalline phase.C–V and I–V measurements were done on the capacitors. Lowest fixed-charge density was found for the nanolaminates deposited at 520 °C. The k values of the nanolaminates extracted by the EOT-physical thickness plots were found to be 141, 48 and 22, for deposition temperatures 420, 520 and 620 °C, respectively. Higher k value for lower deposition temperatures is explained by the thickness dependent morphology of the layers. An with was found for binary HfO₂ layer with 4 nm physical thickness. Lowest leakage current density was for a 4 nm laminate deposited at 420 °C and with a cooling rate of 2 °C/min during PDA.     

Electrochemical Reduction of Tungsten Compounds to Produce Tungsten Powder

The production of tungsten by direct current reduction has been investigated. Experimental studies involved the electrochemical reduction of the solid tungsten compounds tungsten trioxide (WO₃) and calcium tungstate (CaWO₄) in the form of an assembled cathode of porous pellets attached to a current collector. Molten calcium chloride and a molten solution of calcium chloride and sodium chloride at eutectic composition, 48 pct mol NaCl, were used as the electrolytes. Reduced samples were characterized by means of X-ray diffraction analyses and scanning electron microscopy. The results of X-ray analyses, supported with thermodynamic computations, showed that WO₃ cannot be used without loss in processes that involve the use of CaCl₂ at high temperatures because it reacts with CaCl₂ by releasing volatile tungsten oxychloride. In the electrochemical reduction of CaWO₄, X-ray diffraction results indicated the presence of tungsten with significant concentrations of calcium compounds. Metallic tungsten was obtained after treating the reduced samples with dilute hydrochloric acid solutions.