bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Development Study: Channel Fracturing Technique Combined with Rod-shaped Proppant Improves Production, Eliminates Proppant Flowback Issues and Screen-outs in the Western Desert, Egypt
Authors: Abdelhamid Mohamed S. , Marouf M.. , Kamal Y.. , Shaaban A.. , Mathur A.. , Yosry M.. , Kraemer C..
Published: April 2013

The Western Desert of Egypt is a mature hydrocarbon province that has been producing oil and gas for the past 60 years. With the vast majority of the oilfields in decline, almost all wells require hydraulic fracture stimulation to produce economically. This paper describes the application for the first time of a novel channel-fracturing technique combined with rod-shaped proppant in selected production targets in the Cretaceous-aged Abu Roash and Upper Bahariya formations in the El-Fayoum concession in the Egyptian Western Desert. The channel fracturing technique introduces channels within the proppant pack that increase conductivity and effective half-length leading to increased production (Gillard et al. 2010). Rod-shaped proppant when used as tail-in in fracturing treatments increases near-wellbore fracture conductivity and prevents proppant flowback due to its particular geometry (McDaniel et al. 2010).

Many sedimentary features of hydrocarbons in the Western Desert in Egypt are characterized as multi-layered, deltaic, thinly and tightly laminated sandstones consisting of sands with limited lateral and vertical extension with an average permeability of 1 mD and Young's modulus in the order of 2.6 million psi. Historical challenges in the field using conventional hydraulic fracturing have included a premature screen-out rate greater than 45% and subsequently, proppant flowback issues.

A campaign of 4 wells was conducted in the Silah field in the El-Fayoum concession for comparison against 7 offset wells fractured with conventional techniques. With the application of the channel fracturing technique, the screen-out rate of fracturing treatments was reduced to zero, thus eliminating the cost of additional workover rig time or coil tubing cleanup time, and in most cases, the loss of a potentially productive zone. Further, the application of rod-shaped proppant has eliminated proppant flowback. The positive results from implementation of this combined stimulation technique have led to a vigorous expansion of its utilization throughout Egypt's Western Desert area.
Multiphase Boosting in Oil and Gas Production - Recent Applications and Developments
Authors: Müller-Link Dietrich
Published: April 2013

Today's increasing demand for energy calls for a number of different measures to be taken in day-to-day oil and gas production. Scenarios for green fields may require a different approach than full-fledged traditional facilities. Furthermore mature assets or single wells, some of them may have even been shut-in already, gain more and more adherence.

Those brown fields mainly suffer from low wellhead pressures, making them unable to flow even to first stage separation. Moreover, as gathering stations may have been deleted due to an overall decreased production, even longer flow lines will result in a higher pressure demand. If the water content increases additional challenges are rendered. Furthermore regional legal frameworks call for stringent environmentally friendly handling of hydrocarbons. Thus, where gas flaring was state-of-the art in the past it is no longer allowed today. Subsequently the past common production scenarios require adjustments to a considerable extent.

Multiphase pumps are particularly suited, to help overcoming the above-mentioned challenges. Their ability to add energy to the untreated well stream, while reducing the wellhead pressure creates an entirely different pressure regime in the production system. They are capable to pump 100 % gas only, as may be required during oil well start-up and with gas wells suffering from liquid loading. Multiphase pumps are also used to recover the casing gas, thus optimising the hydrodynamic liquid level in the annulus.

While inflow performance is enhanced, differential pressure across down-hole pumps is decreased and at the very system end the gas delivery pressure is increased.

Recent field applications are highlighted and latest technological developments discussed.
Novel Examples of the Use of Surface Jet Pumps (SJPs) to Enhance Production & Processing. Case Studies & Lessons Learnt
Authors: Peeran Syed M , Beg N.. , Sarshar S..
Published: April 2013

Production from many oil and gas fields is restricted as the reservoir pressure drops. This situation becomes worse when water-cut also increases. The restrictions in production also apply to satellite fields or in deep water applications where long distance transport of fluids is involved. In order to maintain production at an economical rate and also to increase total recovery from the field, a production boosting system is always required. Some production boosting solutions require major investment and major changes or upgrading of the existing production system.

Surface Jet Pumps (SJPs) are simple, low cost, passive devices which use a high pressure (HP) fluid as the motive force to boost the pressure of produced gas and liquid phases. The system enables the flowing wellhead pressure (FWHP) to be reduced in order to increase production, whilst meeting the downstream production pressure requirements. A high pressure fluid is needed as the source of energy or motive flow.

The applications of Surface Jet Pumps include revival of dead or liquid loaded oil and gas wells. The oil and gas industry has in recent years become more aware of their applications and benefits.

This paper covers their main applications including boosting production from selected oil and gas wells, boosting the pressure of low pressure gas, prevention of flaring very low pressure gas, eliminating the need for intermediate compressors, de-bottlenecking compressors, preventing HP wells backing out LP wells and revival of liquid loaded wells. In addition to referring to recent field examples, issues such as performance, ranges of operation, key features of the system and solutions for gas or oil production applications are described. The paper also addresses the economic aspects and pay-back periods. Field applications have shown that the recovery of the capital spent in installing surface jet pumps is generally achieved within a few weeks to a few months.
Revising Organic Vapour Respirator Cartridge Change Schedule: a Case Study of a Paint Plant in Iran
Authors: Karimi Ali , Jahangiri Mehdi , Zare Derisi Forough , Nourozi Mohammad Amin
Published: April 2013

After having revised the change schedule for organic vapour respirator cartridges in a paint plant in Iran, we established that it did not provide adequate protection against organic vapours at some workplaces and needed shortening from (48 to 72) h to 4 h. The revision also showed that relying on odour thresholds as the primary means to determine the time to change a chemical cartridge was not effective and that the National Institute for Occupational Safety and Health (NIOSH) MultiVapor service life software program could be applied to develop cartridge change schedules adjusted to specific workplaces.
Biological Significance of the Overexpression of HSP70 and Alpha B-Crystallin in Rat Substantia Nigra Exposed to Different Doses of Permethrin
Authors: Guvenc Dilek , Kabak Yonca Betil , Atmaca Enes , Aksoy Abdurrahman , Guvenc Tolga
Published: April 2013

The aim of this study was to investigate the possible role of the Heat Shock Protein 70 (HSP70) and Alpha B-crystallin (αBC) in the substantia nigra of rats exposed to permethrin at different doses on the apoptotic cell status. The orogastric gavage method was used to administer the different doses of permethrin (75 mg kg-1 in Group I, 150 mg kg-1 in group II, 300 mg kg-1 in group III) to the rats. Using the Western blot test, all the permethrin-treated groups showed a dose-dependent increase in the expression of HSP70 and αBC when compared to the control group. TUNEL positive apoptotic cells were not detected in the dopaminergic neurons of the substantia nigra after treatment with permethrin; however, upon immunofluorescent staining, intense positive reactions for HSP70 and αBC were observed in all of the treated groups. No immunopositive cells were detected in the tissue sections of the control group. These results suggest that the different administered doses of permethrin did not cause apoptotic cell death in the substantia nigra dopaminergic neurons; however, they did induce an increase in HSP70 and αBC expression. Thus, it appears that HSP70 and αBC could play a neuroprotective role in permethrin-induced neurotoxicity.
Soil Structure and Soil Organic Matter of Selected Soil Types in Different Ecosystems
Authors: Tobiašová Erika , Šimanský Vladimír , Dębska Bożena , Banach-Szott Magdalena
Published: April 2013

In this study, differences in soil structure in different ecosystems (forest, meadow, urban, and agro-ecosystem) and soil types (Haplic Chernozem, Haplic Luvisol, Haplic Stagnosol) with a dependence on the influence of quantity and quality of soil organic matter and the particle size distribution on fraction composition of soil aggregates were compared. Soils had different productive capacity and particle size distribution. The most favourable soil structure was in the agro-ecosystem, then in forest, meadow, and urban ecosystem. The worst soil structure was in Haplic Stagnosol. An important indicator in assessing of ecosystem influence, water-resistant macro-aggregates of the 0.5-1 mm size fraction seems to be. This fraction was the only one which was statistically significantly influenced by the ecosystem, and also the only one which was not statistically significantly influenced by the soil type. This fraction also was not influenced either with the quantity and quality of soil organic matter, or with the particle size distribution. The quantity of soil organic matter is reflected in relation to the fractional composition of dry-sieved aggregates and its quality in relation to waterresistant aggregates. Large fractions of water-resistant macro-aggregates were in positive correlation with C : N ratio, the amount of extracted humus substances, or stability and quality of humic acids; while smaller fractions were in negative correlation just with these parameters. Clay and silt fractions had a positive influence on waterresistant macro-aggregates formation, while sand fraction had negative and vice versa.
A Robotized Projective Interface for Human-Robot Learning Scenarios
Authors: De Tommaso Davide , Calinon Sylvain , Caldwell Darwin
Published: April 2013

In this work we discuss a novel robotics interface with perception and projection capabilities for facilitating the skill transfer process. The interface aims at allowing humans and robots to interact with each other in the same environment, with respect to visual feedback. During the learning process, the real workspace can be used as a graphical interface for helping the user to better understand what the robot has learned up to then, to display information about the task or to get feedback and guidance. Thus, the user can incrementally visualize and assess the learner's state and, at the same time, focus on the skill transfer without disrupting the continuity of the teaching interaction. We also propose a proof-of-concept, as a core element of the architecture, based on an experimental setting where a picoprojector and an rgb-depth sensor are mounted onto the end-effector of a 7-DOF robotic arm.
Integral Equations of the Linear Sloshing in an Infinite Chute and Their Discretization
Authors: Gavrilyuk Ivan. P. , Kulyk Anatoli B. , Makarov Vladimir L.
Published: April 2013

A mathematical model of the linear sloshing in an infinite chute with a rectangular section filled by an inviscid incompressible liquid is considered. This model is an abstract second order differential equation in time with a singular integral operator coefficient on a free surface. In the case of a chute with a rib this operator coefficient is defined semi-explicitely through an auxiliary singular integral equation. Mathematical properties of the solution of the model are studied. The fundamental frequencies of the liquid as functions of the width and depth of the rib are investigated. The mathematical model is discretized by using the collocation quadrature method for the operator on the free surface and the Cayley transform method for the time derivative. This fully discrete model is investigated and the error estimates are obtained showing the spectral accuracy with respect to both the spatial and the time discretization parameters.
On the Representation of Functions and Finite Difference Operators on Adaptive Dyadic Grids
Authors: Hemker P.W. , Sprengel F.
Published: April 2013

In this paper we describe methods to approximate functions and dif-
ferential operators on adaptive sparse (dyadic) grids. We distinguish between several
representations of a function on the sparse grid and we describe how finite difference
(FD) operators can be applied to these representations.
For general variable coefficient equations on sparse grids, genuine finite element (FE)
discretizations are not feasible and FD operators allow an easier operator evaluation
than the adapted FE operators. However, the structure of the FD operators is complex.
With the aim to construct an efficient multigrid procedure, we analyze the structure of
the discrete Laplacian in its hierarchical representation and show the relation between
the full and the sparse grid case. The rather complex relations, that are expressed by
scaling matrices for each separate coordinate direction, make us doubt about the pos-
sibility of constructing efficient preconditioners that show spectral equivalence. Hence,
we question the possibility of constructing a natural multigrid algorithm with optimal
O(N) efficiency.
We conjecture that for the efficient solution of a general class of adaptive grid problems
it is better to accept an additional condition for the dyadic grids (condition L) and to
apply adaptive hp-discretization.
Superconvergence Postprocessing for Eigenvalues
Authors: Racheva Milena R. , Andreev Andrey B.
Published: April 2013

The main goal of this paper is to present a new strategy of increasing
the convergence rate for the numerical solution of the linear finite element eigenvalue
problems. This is done by introducing a postprocessing technique for eigenvalues. The
postprocessing technique deals with solving a corresponding linear elliptic problem. We
prove that the proposed algorithm has the superconvergence property of the eigenvalues
and this improvement is attained at a small computational cost. Thus, good finite
element approximations for eigenvalues are obtained on the coarse mesh. The numerical
examples presented and discussed here show that the resulting postprocessing method
is computationally more efficient than the method to which it is applied.
On Multilevel Preconditioners which are Optimal with Respect to Both Problem and Discretization Parameters
Authors: Axelsson O. , Margenov S.
Published: April 2013

Preconditioners based on various multilevel extensions of two-level piecewise linear finite element methods lead to iterative methods which have an optimal order computational complexity with respect to the size (or discretization parameter) of
the system. The methods can be in block matrix factorized form, recursively extended via certain matrix polynomial approximations of the arising Schur complement matrices or on additive, i.e., block diagonal form using stabilizations of the condition number at certain levels. The resulting spectral equivalence holds uniformly with respect to
jumps in the coefficients of the differential operator and for arbitrary triangulations. Such methods were first presented by Axelsson and Vassilevski in the late 1980s. An important part of the algorithm is the treatment of systems with a diagonal block matrix, which arises on each finer level in a recursive refinement method and corresponds
to the added degrees of freedom on that level. This block is well-conditioned for model type problems but becomes increasingly ill-conditioned when the coefficient matrix becomes more anisotropic or, equivalently, when the mesh aspect ratio increases. This paper presents some methods for approximating this matrix also leading to a preconditioner
with spectral equivalence bounds which hold uniformly with respect to both the problem and the discretization parameters. Therefore, the same holds also for the preconditioner to the global matrix.
Jacobi-Bernstein Basis Transformation
Authors: Rababah Abedallah
Published: April 2013

In this paper we derive the matrix of transformation of the Jacobi
polynomial basis form into the Bernstein polynomial basis of the same degree n and
vice versa. This enables us to combine the superior least-squares performance of the
Jacobi polynomials with the geometrical insight of the Bernstein form. Application to
the inversion of the Bézier curves is given.
A Two Point Difference Scheme of an Arbitrary Order of Accuracy for BVPS for Systems of First Order Nonlinear Odes
Authors: Makarov V.L. , Gavrilyuk I.P. , Kutniv M.V. , Hermann M.
Published: April 2013

We consider two-point boundary value problems for systems of first-order
nonlinear ordinary differential equations. Under natural conditions we show that
on an arbitrary grid there exists a unique two-point exact difference scheme (EDS),
i.e., a difference scheme whose solution coincides with the projection onto the grid of
the exact solution of the corresponding system of differential equations. A constructive
algorithm is proposed in order to derive from the EDS a so-called truncated difference
scheme of an arbitrary rank. The m-TDS represents a system of nonlinear
algebraic equations with respect to the approximate values of the exact solution on
the grid. Iterative methods for its numerical solution are discussed. Analytical and
numerical examples are given which illustrate the theorems proved.
Keywords: systems of nonlinear ordinary differential equations, difference scheme,
exact difference scheme, truncated difference scheme of an arbitrary order of accuracy,
fixed point iteration.
The Influence of Higher Order FEM Discretisations on Multigrid Convergence
Authors: Köster M. , Turek S.
Published: April 2013

Quadratic and even higher order finite elements are interesting candidates
for the numerical solution of partial differential equations (PDEs) due to their
improved approximation properties in comparison to linear approaches. The systems of
equations that arise from the discretisation of the underlying (elliptic) PDEs are often
solved by iterative solvers like preconditioned Krylow-space methods, while multigrid
solvers are still rarely used – which might be caused by the high effort that is associated
with the realisation of the necessary data structures as well as smoothing and intergrid
transfer operators.
In this note, we discuss the numerical analysis of quadratic conforming finite elements
in a multigrid solver. Using the “correct” grid transfer operators in conjunction
with a quadratic finite element approximation allows to formulate an improved approximation
property which enhances the (asymptotic) behaviour of multigrid: If m
denotes the number of smoothing steps, the convergence rates behave asymptotically
like O(1/m2) in contrast to O(1/m) for linear FEM.
On Improved Approximate Solution of the Fredholm Integral Equation
Authors: Berikelashvili G. , Karkarashvili G.
Published: April 2013

A method of approximate solution of the linear one-dimensional Fredholm
integral equation of the second kind is constructed. With the help of the Steklov
averaging operator the integral equation is approximated by a system of linear algebraic
equations. On the basis of the approximation used an increased order convergence
solution has been obtained.
Fundamental Solutions of PDEs as Radial Basis Functions in Multivariate Interpolation
Authors: Masjukov A.
Published: April 2013

For bivariate and trivariate interpolation we propose in this paper a
set of integrable radial basis functions (RBFs). These RBFs are found as fundamental
solutions of appropriate PDEs and they are optimal in a special sense. The condition
number of the interpolation matrices as well as the order of convergence of the inter-
polation are estimated. Moreover, the proposed RBFs provide smooth approximations
and approximate fulfillment of the interpolation conditions. This property allows us
to avoid the undecidable problem of choosing the right scale parameter for the RBFs.
Instead we propose an iterative procedure in which a sequence of improving approx-
imations is obtained by means of a decreasing sequence of scale parameters in an a
priori given range. The paper provides a few clear examples of the advantage of the
proposed interpolation method.
On The Parallel Multiblock Geometric Multigrid Algorithm
Authors: CIEGIS R. , GASPAR F. , RODRIGO C.
Published: April 2013

The application of a parallel multiblock geometric multigrid is consid-ered. It is applied to solve a two-dimensional poroelastic model. This system of PDEs is approximated by a special stabilized monotone finite-difference scheme. The obtained system of linear algebraic equations is solved by a multigrid method, when a domain is partitioned into structured blocks. A new strategy for the solution of the discrete problem on the coarsest grid is proposed and the efficiency of the obtained algorithm is investigated. The geometrical structure of the sequential multigrid method is used to develop a parallel version of the multigrid algorithm. The convergence properties of several smoothers are investigated and some computational results are presented.
Convergence Rates For Lavrentiev-Type Regularization In Hilbert Scales
Authors: NAIR M.T. , TAUTENHAHN U.
Published: April 2013

For solving linear ill-posed problems with noisy data regularization methods are required. We analyze a simplified regularization scheme in Hilbert scales for operator equations with nonnegative self-adjoint operators. By exploiting the op-erator monotonicity of certain functions, order-optimal error bounds are derived that characterize the accuracy of the regularized approximations. These error bounds have been obtained under general smoothness conditions.
Bifurcation Analysis Of Nonlinear Parameterized Two-Point Bvps With Liapunov — Schmidt Reduced Functions
Authors: HERMANN M. , MILDE T.H.
Published: April 2013

In this paper, we study nonlinear two-point boundary value problems (BVPs) which depend on an external control parameter. In order to determine numeri-cally the singular points (turning or bifurcation points) of such a problem with so-called extended systems and to realize branch switching, some information on the type of the singularity is required. In this paper, we propose a strategy to gain numerically this information. It is based on strongly equivalent approximations of the corresponding Liapunov — Schmidt reduced function which are generated by a simplified Newton method. The graph of the reduced function makes it possible to determine the type of singularity. The efficiency of our numerical-graphical technique is demonstrated for two BVPs.
Numerical Solution Of A Hyperbolic Transmission Problem
Authors: JOVANOVIC B.S. , VULKOV L.G.
Published: April 2013

In this paper we investigate an initial boundary value problem for a one-dimensional hyperbolic equation in two disconnected intervals. A finite difference scheme approximating this problem is proposed and analyzed. An estimate of the convergence rate has been obtained.
Image Edge Respecting Denoising with Edge Denoising by a Designer Nonisotropic Structure Tensor Method
Authors: Santitissadeekorn N. , Bollt E.M.
Published: April 2013

We consider image denoising as the problem of removing spurious
oscillations due to noise while preserving edges in the images. We will suggest here
how to directly make infinitesimal adjustment to standard variational methods of
image denoising, to enhance desirable target assumption of the noiseless image. The
standard regularization method is used to define a suitable energy functional to
penalize the data fidelity and the smoothness of the solution. This energy functional
is tailored so that the region with small gradient is isotropically smoothed whereas in
a neighborhood of an edge presented by a large gradient smoothing is allowed only
along the edge contour. The regularized solution that arises in this fashion is then the
solution of a variational principle.
To this end the associated Euler — Lagrange equation needs to be solved numerically
and the half-quadratic minimization is generally used to linearize the equation and to
derive an iterative scheme. We describe here a method to modify Euler — Largrange
equation from commonly used energy functionals, in a way to enhance certain desirable
preconceived assumptions of the image, such as edge preservation. From an algorithmic
point of view, we may deem this algorithm as a smoothing by a local average with an
adaptive gradient-based weight. However, this algorithm may result in noisy edges
although the edge is preserved and noise is suppressed in the low-gradient regions of
the image. The main focus here is to present an edge-preserving regularization in the
aforementioned view point, and to provide an alternative and simple way to modify the
existing algorithm to mitigate the phenomena of noisy edges without explicitly defining
step where we specify an energy functional to be minimized.
A Problem-Independent Slope Limiting Algorithm for the Runge-Kutta Discontinuous Galerkin Method
Authors: Tokareva S.A.
Published: April 2013

This paper deals with the new algorithm of slope limiting in the Runge-
Kutta discontinuous Galerkin (RKDG) method. The slope limiting is applied at each
intermediate step of the Runge-Kutta process to guarantee the monotonicity of the
resulting RKDG scheme. The standard formulation of the RKDG method assumes a
manual prescription of the special parameter used in the limiting procedure. Such definition
of the limiter makes the method problem-dependent, which is disadvantageous
for practical computations. A new problem-independent way of estimating the limiting
parameter is proposed and its performance in the second- and third-order RKDG
methods is studied in this paper.
Computational Analysis of Displacement of Particles with Given Size on the Nonstationary Bulging Membrane as a Theoretical Model of Membrane Fouling
Authors: Gac Jakub M. , Gradoń Leon
Published: April 2013

A simple model of behaviour of a single particle on the bulging membrane was presented. As a result of numerical solution of a motion equation the influence of the amplitude and frequency of bulging as well as the particle size on particle behaviour, especially its downstream velocity was investigated. It was found that the bulging of a membrane may increase the mean velocity of a particle or reinforce its diffusive behaviour, dependeing on the permeation velocity. The obtained results may help to design new production methods of highly fouling-resistant membranes.
Shades of Freire: Exorcising the spectre haunting pedagogy
Authors: Wilkins Andrew
Published: April 2013

In the second part of this special issue on neoliberalism, pedagogy and curriculum, I explore the contributions of each author to confronting neo-liberal reforms of education, notably the spectre of neo-liberalism haunting aspects of pedagogy, teaching and curriculum. Exemplary of the scholarly work produced by many critical educators, the contributing authors share an understanding of the oppressive function of educational apparatuses and their complicity with the reproduction of dominant epistemes of knowledge/power. In this case, neo-liberalism is defined as a canonical narrative through which existing education relations, practices and discourses are structured and mediated. Against this neo-liberal imaginary, the authors argue in favour of models of knowing, learning and teaching that work to sustain practices of critical inquiry and self-discovery among learners as active, reflexive and engaged subjects. The result is a timely collection of papers critiquing the nuances pertaining to the global transmission of neo-liberal education and a much- -needed reinvigoration of the Freirean demand for a liberating and critical pedagogy.
Preliminary Study on the Use of Ozonation for the Degradation of Dithiocarbamate Residues in the Fruit Drying Process: Mancozeb Residue in Blackcurrant is the Example Used
Authors: Antos Piotr , Kurdziel Anna , Sadło Stanisław , Balawejder Maciej
Published: April 2013

In order to reduce the level of dithiocarbamate fungicide mancozeb residues in blackcurrants, two different ozone treatment procedures were evaluated. The first one entailed washing the plant material with an aqueous solution of ozone. This ozone enriched water solution allowed for a 59% reduction of mancozeb residues, compared with the initial concentration. The latter method was based on the utilization of ozone in a gaseous phase combined with a drying process. In that procedure, samples of blackcurrant fruit were exposed to a 19 ppm ozone concentration, and then the blackcurrants were dried. The utilization of ozone in a gaseous phase permitted a 38% reduction of mancozeb residues, in comparison with the initial concentration. As a result of the combination of both processes; ozonation and drying, a 58% reduction of mancozeb residues was achieved.
Full Dynamic Reactions in the Basic Shaft Bearings of Big Band Saw Machines
Authors: Marinov Boycho
Published: April 2013

The band saws machines are a certain class woodworking machines for longitudinal or transversal cutting as well as for curvilinear wood cutting. These machines saw the wood through a band-saw blade and two feeding wheels. These wheels usually are very large and they are produced with inaccuracies. The centre of mass of the disc is displaced from the axis of rotation of the distance e (eccentricity) and the axis of the disk makes an angle with the axis of rotation. In this paper, the dy- namic reactions in the bearings of the basic shaft, which drives the band saw machines, are analyzed. These reactions are caused by the external loading and the kinematics and the mass characteristics of the rotating disk. The expressions for the full dynamic reactions are obtained. These expressions allow the parameters of the machines to be chosen in such a way that the loading in the shaft and the bearings to be minimal.
Diagnosis of Type, Location and Size of Cracks by Using Generalized Differential Quadrature and Rayleigh Quotient Methods
Authors: Akbarzadeh Khorshidi Majid , Soltani Delara
Published: April 2013

In this paper, an appropriate and accurate algorithm is pro- posed to diagnosis of lateral or vertical cracks on beam, based on beam natural frequencies. Clamped-free boundary conditions are assumed for the beam. The crack in beam is modelled by without mass torsion spring. Then, the relationship between the beam natural frequencies, location and stiffness of the crack is presented by using the Rayleigh quotient and the governing equation is solved by using generalized differential quadrature method (GDQM). If there is only one crack in the beam, then three natural frequencies are used as inputs to the algorithm and mode shapes corresponding to each the natural frequencies are calculated. Finally, type, location and severity of cracks in beam, are diagnosed.
Virtual Coordinate Measuring Machine Built Using Lasertracer System and Spherical Standard
Authors: Sładek Jerzy , Gąska Adam , Olszewska Magdalena , Kupiec Robert , Krawczyk Marcin
Published: April 2013

Improvements of modern manufacturing techniques implies more efficient production but also new challenges for coordinate metrologists. The crucial task here is a coordinate measurement accuracy assessment. It is important because according to technological requirements, measurements are useful only when they are stated with their accuracy. Currently used methods for the measurements accuracy estimation are difficult to implement and time consuming. It is therefore important to implement correct and validated methods that will also be easy to implement. The method presented in this paper is one of them. It is an on-line accuracy estimation method based on the virtual CMM idea. A model is built using a modern LaserTracer system and a common test sphere and its implementation lasts less than one day. Results obtained using the presented method are comparable to results of commonly used uncertainty estimation methods which proves its correct functioning. Its properties predispose it to be widely used both in laboratory and industrial conditions.
Management of Truncated Data in Speech Transmission Evaluation for Pupils in Classrooms
Authors: Genta G. , Astolf A. , Bottalico P. , Barbato G. , Levi R.
Published: April 2013

Speech intelligibility is a subjective performance index defined as the percentage of a message understood correctly. Often the results of speech intelligibility tests would suggest that conditions are acceptable, with Intelligibility Score (IS) of the order of 90% or more, while speech transmission performance may not be satisfactory. Subjective ratings of the Listening Easiness Score (LES), based on a discrete questionnaire, provide an alternative approach. A total of 239 primary school pupils, aged 7 to 11, evenly distributed among the grades, participated in the survey. The objective indicator Speech Transmission Index (STI) was also measured for each test setting in seven different positions in the laboratory classroom used for the test. Both IS and LES are inherently bounded, and their data distributions exhibit a significant accumulation of scores in the upper and lower parts. The resulting truncation problem has been addressed with a method based on the normal probability plot, enabling identification of mathematical models relating IS and LES to STI, as well as the estimation of related uncertainties. IS and LES exhibit substantially similar metrological capabilities, as, for both, model relative uncertainty does not exceed 4% and uncertainties in prediction of new observations are about twice as large.
Optimizing Natural Gas Fueling Station Reservoirs Pressure Based on Ideal Gas Model
Authors: Farzaneh-Gord Mahmood , Deymi-Dashtebayaz Mahdi
Published: April 2013

At CNG fuelling station, natural gas is usually stored in a cascade storage system to utilize the station more efficient. The cascade storage system is generally divided into three reservoirs, commonly termed low, medium and high-pressure reservoirs. The pressures within these three reservoirs have huge effects on the performance of a CNG fuelling station and a fast filling process of natural gas vehicle’s (NGV) cylinder. A theoretical analysis is developed to study the effects of the reservoirs pressures and temperatures on the performance of the CNG station. The analysis is based on the first and the second law of thermodynamics, conservation of mass and ideal gas assumptions. The results show that as the reservoir temperature decreases, the fill ratio increases and the pressure within the filling station reservoirs has no effects on the fill ratio. The non-dimensional entropy generation and filling time profiles have opposite trends and as entropy generation decreases, the filling time increases. The optimized non-dimensional low and medium pressure-reservoir pressures are found to be as 0.24 and 0.58 respectively in thermodynamic point of view.
Evaluation of acute/late toxicity and local recurrence in Τ1-Τ2 glottic carcinoma treated with accelerated hypofractionated 3D-conformal external beam radiotherapy (3D-CRT)
Authors: Kouloulias Vassilis E. , Zygogianni Anna , Mosa Eftychia , Platoni Kalliopi , Georgakopoulos John , Antypas Christos , Beli Ivelina , Tolia Maria , Maragoudakis Paulos , Giotakis Ioannis , Papas Zisis , Psyrri Amanda , Kelekis Nikolaos , Kouvaris John
Published: April 2013

Background.The aim of the study was to evaluate the efficacy, as well as the acute and late toxicity of an accelerated hypofractionated 3DCRT schedule as radical treatment in patients with organ confined glottic cancer cT1-2N0.

Patients and methods. Between June of 2004 and September 2010, 47 retrospectively selected patients (29 males, 18 females) diagnosed with organ confined T1 or T2 glottic cancer, were treated with external 3DCRT in an accelerated hypofractionation schedule. The median age was 70 years. A dose of 64.4 Gy in 28 daily fractions was prescribed. The primary study endpoints were to assess the acute and late effects of radiation toxicity, according to the EORTC/ RTOG scale, as well as the therapeutic impact of this schedule in terms of local recurrence.

Results. The median follow up was 36 months. At the end of radiotherapy, grade I, II and III acute toxicity was observed in 34, 9 and4 patients, respectively. Late grade I and II toxicity was observed in 25 and in 8 patients respectively. Only two local recurrences were observed, 15 and 24 months post 3DCRT respectively.

Conclusions. Our radiotherapy schedule achieves a high locoregional control rate with the advantage of voice preservation. The proposed hypofractionated schedule can be recommended as a standard radiotherapy treatment, since these results are comparable with those of conventional fractionation schedules.
Mapping as a Spatial Data Source
Authors: Hudecová Ľubica
Published: April 2013

The basic database for a geographic information system (BD GIS) forms the core of a national spatial data infrastructure. Nowadays decisions are being made about the potential data sources for additional data updates and refinement of the BD GIS. Will the data from departmental or other information system administrators serve for this purpose?

This paper gives an answer as to whether it is advisable to use “geodetic mapping” (the results realized in the process of land consolidation) or “cadastral mapping” (the results realized in the process of the renewal of cadastral documentation by new mapping) for additional data updates. In our analysis we focus on the quality parameters at the individual data element level, namely the positional accuracy, attribute accuracy, logical consistency, and data resolution. The results of the analysis are compared with the contents of the Object Class Catalog of BD GIS (OCC), which describes the group of objects managed by BD GIS and defines the data collection methods, types of geometry and its properties.
Migration of Passerines through some Protected Areas in the Eastern Part of Egypt
Authors: Wed Abdel Latif Ibrahim , Busse Przemysław
Published: April 2013

Ibrahim W.A.L., Busse P. 2012. Migration of passerines through some protected areas in the
eastern part of Egypt. Ring 34: 69-205.

The fieldwork - catching and ringing birds using mist-nets - were conducted at several sites during both spring and autumn migration seasons in 2001-2008. These sites were: Burullus Protected Area, Wadi El Rayan Protected Area, Hurghada, Sharm El Shiekh (Ras Mohamed National Park), Saluga and Ghazala Protected Area and Wadi El Gemal Protected Area. Altogether 21 site/seasons were covered (9 in spring and 12 autumn). In the most cases the work in a season lasted 1-2 months and the timing of work was not standardized. This make the results not exactly compatible, but still this is a first so wide study of the mainly passerine migration over the area. The aim of this paper is to make accessible the basic information on passerine migration there. Some non-passerines, that are more easily caught with mist-nets or that are caught ocassionally are listed too. Altogether 19 748 individuals of 117 species were ringed in spring and 11 238 individuals in autumn. The data are presented in the text as faunistics style lists of birds caught in spring and autumn separately, as tables of birds ringed at stations and those that show relative abundance and dominance of species and in Appendices I and II (for spring and autumn) as maps with average numbers per station and as seasonal number dynamics - total for seasons and yearly, if possible. The data included in the paper are treated as a source information about migration over the area studied, while the more detailed data about migration pattern, measurements, stopover ecology will be evaluated in next papers being under preparation.
Rural schools: wrinklers for mayors?
Authors: Trnková Kateřina
Published: April 2013

Rural schools: wrinklers for mayors?

All municipalities in the Czech Republic are obliged to guarantee access to basic education for children eligible for compulsory schooling. To meet this task, most municipalities establish a primary school whose operational and investment costs they cover. Running a school can be very demanding for rural municipalities. The article presents the results of a questionnaire survey which involved founders (mayors) the so-called small schools with composite classes, situated mainly in small rural municipalities. Based on these results examines the main stereotypes associated with the notion of small rural schools. A hypothetical balance between what the municipality must invest and what benefits the school brings is sought.
ICT-Enabled Climate Change Education for Sustainable Development Across the School Curriculum
Authors: Makrakis Vassilios , Larios Nikos , Kaliantzi Gkolfo
Published: April 2013

A radical shift in pedagogy is necessary for information and communication technology (ICT) to enhance teaching and learning for sustainability. Climate change takes an inter/crossdisciplinary approach attempting to synthesise diverse ideas and observations concerning global warming. This paper deals with the integration of climate change across the school curriculum through a web-based hypermedia application entitled ICT-enabled integration of climate change education (CCE) that is used as a resource for the EU-funded project ICT-enabled education for sustainable development (ESD). The web-based environment includes interactive activities and supportive material on climate change and is open to all the six forms at the primary school level. The methodological approach used merges ICT, ESD, critical pedagogy and CCE principles and practices. Drupal (content management system) was chosen as the back-end system of our hypermedia learning environment. The main learning content is composed of learning objects (LOs) created through the authoring tool Adobe Flash. The combination of Drupal and Flash provides a dynamic and adaptable learning environment. Through this web-based learning environment that integrates six thematic areas supported by various ICT tools, learners are expected to gain insight into how climate change is altering the planet, potential impacts on the future, and how they can intervene to address its effects.
The structure of the fréchet space s regarding the series ∑ƒn(xn)
Authors: Šalát Tibor , Vadovič Peter
Published: April 2013

We investigate the subsets of the Fr´echet space s of all sequences of real numbers equipped with the Fr´echet metric ρ from the Baire category point of view. In particular, we concentrate on the “convergence” sets of the series ∑ƒn (xn) that is, sets of sequences x = (xn) for which the series converges, or has a sum (perhaps infinite), or oscillates. Provided all ƒn are continuous real functions, sufficient conditions are given for the “convergence” sets to be of the first Baire category or residual in s.
Formal analysis of security protocols for wireless sensor networks
Authors: Novotný Marián
Published: April 2013

Design of security protocols is notoriously error-prone. For this reason, it is required to use formal methods to analyze their security properties. In the paper we present a formal analysis of the Canvas protocol. The Canvas protocol was developed by Harald Vogt and should provide data integrity inWireless Sensor Networks. However, Dieter Gollmann published an attack on the protocol. We consider the fallacy of the Canvas scheme in different models of the attacker and present a solution for correcting the scheme.We propose a formal model of the fixed Canvas protocol in the applied pi-calculus. This model includes a model of the network topology, communication channels, captured nodes, and capabilities of the attacker. Moreover, we formulate and analyze the data integrity property of the scheme in the semantic model of the applied pi-calculus. We prove that the fixed Canvas scheme, in the presence of an active adversary, provides data integrity of messages assuming that captured nodes are not direct neighbors in the communication graph of a sensor network. Finally, we discuss the applicability of the proposed formal model for analysis of other WSN security protocols.
Effect of Energy Distribution on the Efficiency of an All-Wheel Drive Electric Vehicle Powertrain
Authors: Barák Adam
Published: April 2013

SHRNUTÍ

Članek popisuje simulaci elektrickeho vozidla s pohonem všech kol včetně implementace jednoduche optimalizačni funkce pro určeni optimalniho rozloženi vykonů mezi napravy s ohledem na minimalni ztraty v pohonnem řetězci. Model zkoumaneho elektrickeho vozidla je popsan vicehmotovou soustavou v programu Matlab/Simulink. Optimalizačni funkce určuje v každem časovem kroku simulace poměr rozděleni vykonu mezi motorem na předni a motorem na zadni napravě tak, aby celkovy ztratovy vykon obou motorů byl minimalni. V članku je na přikladu simulace jizdy vozidla v NEDC ukazan přinos optimalizace rozděleni vykonů mezi jednotlivymi elektromotory pro různa uspořadani pohonneho řetězce.
Clinical and laboratory study of pro-inflammatory and anti-inflammatory cytokines in women with multiple sclerosis
Authors: Trenova Anastasiya G. , Manova Mariya G. , Kostadinova Ivanka I. , Murdjeva Mariana A. , Hristova Dimka R. , Vasileva Tonka V. , Zahariev Zahari I.
Published: April 2013

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system characterised with a complex system of interactions between proinflammatory and anti-inflammatory cytokines in its course.

Aim: The aim of the present study was to investigate the serum levels of cytokines TNF-α, IFN- γ, IL- 4 and IL- 10 in female patients with MS and healthy individuals, the changes occurring in the relapse and remission phases of the disease and their correlation with the severity of the neurological deficit.

Patients and methods: Thirty-five women with relapsing-remitting MS were examined. The patients’ age ranged between 18 and 50 years and MS was verified clinically and by magnetic resonance imaging according to the McDonald criteria. Thirteen of the patients were treated with interferon-β-1b. The serum concentrations of TNF-α, IFN- γ, IL- 4 and IL- 10 were determined twice - in relapse and in remission - using an enzyme-linked immunosorbent assay (EL ISA). The control group consisted of 35 age-matched healthy females. Results: The comparison of cytokine serum concentrations during the two phases of the disease showed significant elevation of the TNF-α serum levels in the relapse phase and of IL- 4 - in the remission phase. The comparison between the patients and the healthy control subjects demonstrated statistically significant lower concentrations of TNF-α in remission patients and higher concentrations of IL- 10 in relapse patients. The patients with interferon-β-1b treatment showed different profile of cytokine secretion from the patients without interferon-β-1b treatment. Interferon-β-1b-treated patients showed significantly lower serum levels of TNF-α and IFN- γ during the relapse phase and higher TNF-α and IL- 10 serum levels during the remission phase compared with the untreated patients.

Conclusions: Serum levels of TNF-α and IL- 4 objectively reflect the immune response during relapse and remission of the disease. The severity of neurological deficit as estimated with the expanded disability status scale (EDSS ) does not depend on the serum levels of TNF-α, IL- 10 and IFN- γ in the two phases of MS.
Lectotypification of the Linnaean name Bryonia cretica (Cucurbitaceae)
Authors: Iamonico Duilio , Panitsa Maria
Published: April 2013

The typification of the name Bryonia cretica is investigated and discussed. A specimen from the Clifford Herbarium is designated as the lectotype. The morphology of the species, notes on its cytology and geographical distribution and ecological features are also treated.