1,309 research outputs found
Tubing specifications selection and its effect on the results of hydraulic fracturing treatment in oil formations
Equipment specification, data collection and design
process are critical factors for any hydraulic fracturing
treatment success. This paper investigates tubing
specifications selection and its effect on the results of
hydraulic fracturing treatment in oil formations.
Simulations were carried out on well E-45 owned by
National Oil Corporation (NOC) of Libya using two
main tools - Pumping Diagnostic Analysis Toolkit
(PDAT) and Halliburton proprietary software package
(FracPro) for analysing Mini-Frac pumping data. The
initial modelling results using 3.5 inch tubing were
compared with the experimental results obtained from
the actual hydraulic fracturing tests carried out at the E45 by Halliburton as a sub-contractor for NOC. The
simulation results showed good agreement with the
experiments, validating the model.
The model was then extended to explore alternate tubing
diameters. This was implemented by introducing the
relationship between the tub friction pressures and
pumping rate (Friction Pressure vs. Pumping Rate) with
the mentioned tube sizes. The results showed that in
high stress rock formations, it is worthwhile to minimise
the pipe friction by using higher tubing grade (4.5
inches) and burst pressure. A bigger tubing inner
diameter can increase the allowable surface pumping
rate and pressure
Learning based automatic face annotation for arbitrary poses and expressions from frontal images only
Statistical approaches for building non-rigid deformable models, such as the active appearance model (AAM), have enjoyed great popularity in recent years, but typically require tedious manual annotation of training images. In this paper, a learning based approach for the automatic annotation of visually deformable objects from a single annotated frontal image is presented and demonstrated on the example of automatically annotating face images that can be used for building AAMs for fitting and tracking. This approach employs the idea of initially learning the correspondences between landmarks in a frontal image and a set of training images with a face in arbitrary poses. Using this learner, virtual images of unseen faces at any arbitrary pose for which the learner was trained can be reconstructed by predicting the new landmark locations and warping the texture from the frontal image. View-based AAMs are then built from the virtual images and used for automatically annotating unseen images, including images of different facial expressions, at any random pose within the maximum range spanned by the virtually reconstructed images. The approach is experimentally validated by automatically annotating face images from three different databases
Two new records of Plagiothecium from India
Abstract
Govind Wild Life Sanctuary in the Western Himalayas with its diverse vegetation types provides excellent habitats and microclimates for a lush growth of bryophytes. During investigations on the bryophytes of this region Plagiothecium euryphyllum (Cardot et Thér.) Z. Iwats. and P. cavifolium (Brid.) Z. Iwats. have been identified for the first time from India. P. euryphyllum is characterised by bright green to yellowish green plants, irregularly branched, complanate. Central strand developed. Leaves erectopatent, imbricate, ovate oblong, margin entire, acute to acuminate at apex, costa two forked, decurrent with hyaline, rectangular cells. Seta reddish, capsule erect to inclined, while plants of P. cavifolium are yellowish green, glossy, prostrate, irregularly branched, branches julaceous. Leaves appressed to stem, closely imbricate, erectopatent, ovate lanceolate, symmetrical, margin minutely dentate at apex, cells at alar region rectangular costa two short. Seta reddish brown, capsule erect, pyriform. A morpho-taxonomic account of above two taxa is provided
REPRESENTATION SCHEMES FOR MATHEMATICAL PROGRAMMING MODELS
Because of the difficulties often experienced in formulating and
understanding large scale models, much current research is directed
towards developing systems to support the construction and
understanding of management science models. This paper discusses
seven different methods for representing mathematical programming
models during the formulation phase of the modeling process. The
approaches discussed are block-schematic, algebraic, three different
kinds of graphical schemes, a database-oriented approach and
Structured Modeling. We emphasize representations that have graphical
elements suitable for incorporation in the interface to a modeling
system. The different methods are compared using a common example and
the transformations that allow one to go from one representation to
another are discussed.Information Systems Working Papers Serie
Vocal cord palsy in an infant with myelomeningocoele
In this article we describe the case of a four-month-old male infant with myelomeningocoele, who presented with inspiratory stridor and vocal cord palsy (VCP). Hindbrain dysfunction is a leading cause of mortality and morbidity in children with neural tube defects. It is important to consider the above in the differential diagnosis of infants with breathing difficulties. A discussion of myelodysplasia, Arnold-Chiari malformations, bilateral VCP and anaesthesia management is presented.South Afr J Anaesth Analg, 2011;17(6):394-39
Neural apparent BRDF fields for multiview photometric stereo
We propose to tackle the multiview photometric stereo problem using an
extension of Neural Radiance Fields (NeRFs), conditioned on light source
direction. The geometric part of our neural representation predicts surface
normal direction, allowing us to reason about local surface reflectance. The
appearance part of our neural representation is decomposed into a neural
bidirectional reflectance function (BRDF), learnt as part of the fitting
process, and a shadow prediction network (conditioned on light source
direction) allowing us to model the apparent BRDF. This balance of learnt
components with inductive biases based on physical image formation models
allows us to extrapolate far from the light source and viewer directions
observed during training. We demonstrate our approach on a multiview
photometric stereo benchmark and show that competitive performance can be
obtained with the neural density representation of a NeRF.Comment: 9 pages, 6 figures, 1 tabl
REPRESENTATION SCHEMES FOR MATHEMATICAL PROGRAMMING MODELS
Because of the difficulties often experienced in formulating and
understanding large scale models, much current research is directed
towards developing systems to support the construction and
understanding of management science models. This paper discusses six
different methods for representing mathematical programming models
during the formulation phase of the modeling process. The approaches
discussed in the paper include algebra, three different kinds of
graphical schemes, a database-oriented approach and Structured
Modeling. We emphasize representations that have graphical elements
suitable for incorporation in the interface to a modeling system. The
different methods are compared using a common example and conclusions
are drawn as to their suitability for various modeling tasks and
situations.Information Systems Working Papers Serie
Thermodynamic study of heavy metals behavior during municipal waste incineration
The incineration of municipal solid waste (MSW) contributes significantly to the presence of heavy metals in urban area aerosols. It is thus important to ascertain the quantities and chemical forms of the heavy metals (HM) that are emitted from the incineration plant stacks. The behaviour of HM, which depends strongly on the thermal and chemical environments, was investigated herein with a modelling approach, consisting of several parts. First, a refuse bed combustion model was developed for simulating on-grate MSW incineration. It describes most of the physico-chemical and thermal phenomena occurring during waste combustion. Second, results from the bed model were taken as boundary conditions to perform 3D simulations of the post-combustion zone and of the boiler. The case studied was of the Strasbourg incineration plant. Finally, the local thermal conditions and the local elementary compositions of gas and solid phases obtained from these simulations were used to carry out thermodynamic calculations of the speciation of HM at each point in the incinerator. The results for four metals (Cd, Zn, Pb, Cr) are presented, discussed and compared to available data. Predicted species are in agreement with observations for volatile metals, except lead, whose volatilization seems overestimated
Development of NiAl-Based Intermetallic Alloys: Effect of Chromium Addition
The mechanical behavior of dual-phase NiAl(Cr) microstructures, consisting of elongated primary NiAl grains aligned with an intergranular NiAl-Cr eutectic phase, produced by extrusion of a cast NiAl(Cr) alloy, has been examined. Chromium addition to create a dual phase NiAl-based aligned microstructure leads to large increases in the yield strength but no significant toughness improvement. This is achieved primarily by solid solution hardening and precipitation hardening. The constitutional hardening rate resulting from deviations from stoichiometry in the nickel-rich NiAl was estimated to be about 66 MPa per atomic per cent of nickel
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