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PL
W technologii uszczelniania kolumn rur okładzinowych w otworze wiertniczym zachodzi niekiedy potrzeba zastosowania zaczynu o obniżonej gęstości. Najczęściej ma to miejsce w przypadku uszczelniania otworu wierconego w strefie niskiego ciśnienia złożowego. Aby zaprojektować recepturę zaczynu lekkiego, stosuje się dodatek materiału wypełniającego, którego gęstość jest znacznie niższa niż gęstość cementu. Jednak obecność takiego dodatku w strukturze płynnego zaczynu cementowego może niekiedy powodować destabilizację układu objawiającą się nadmiernym frakcjonowaniem, w wyniku czego lekkie cząsteczki migrują w górne partie zaczynu, a ciężkie ziarna cementu opadają na dno. Ponadto zaczyny zawierające dodatki lekkie wykazują również obniżone wartości parametrów mechanicznych, większą porowatość i przepuszczalność dla gazu. Cechy te mogą dyskwalifikować dany zaczyn pod kątem zastosowania go w warunkach otworowych. W celu wyeliminowania tych niekorzystnych zmian zachodzących w strukturze zarówno płynnego, jak i stwardniałego zaczynu lekkiego, stosuje się domieszki pozwalające na znaczną poprawę parametrów technologicznych projektowanej receptury. Odpowiedni dobór zarówno ilościowy, jak i jakościowy wybranych środków umożliwia wyeliminowanie frakcjonowania zaczynu, w wyniku czego możliwe jest uzyskanie homogenicznej struktury płynnego zaczynu, a powstały po związaniu płaszcz cementowy będzie wykazywał izotropię badanych parametrów. Ponadto dodatki i domieszki drobnocząsteczkowe pozwalają doszczelnić matrycę płaszcza cementowego w taki sposób, że wytrzymałość na ściskanie ulega znacznej poprawie i zredukowana zostaje wartość przepuszczalności i porowatości. W artykule zostały omówione wyniki badań nad opracowaniem receptur zaczynów lekkich przeznaczonych do uszczelniania otworów w strefie niskich ciśnień złożowych. Jako próbkę kontrolną przyjęto recepturę, która była stosowana w warunkach otworowych. Zaczyn ten ze względu na brak stabilności sedymentacyjnej został wytypowany do modyfikacji. Kolejne receptury zawierały zróżnicowane ilości materiałów wypełniających. Jako dodatki lekkie użyto: perlit filtracyjny, mikrosferę glinokrzemianową oraz mikrosferę szklaną. Natomiast w celu poprawy stabilności sedymentacyjnej i uzyskania odpowiednich wartości parametrów mechanicznych użyto dwie formy krzemionki: koloidalny roztwór krzemianu sodu oraz nanokrzemionkę hydrofilową. Zaprojektowane receptury zaczynów charakteryzowały się odpowiednimi wartościami parametrów technologicznych i stabilnością sedymentacyjną. Wprowadzone modyfikacje w recepturach zaczynów pozwoliły na osiągnięcie homogenicznej mikrostruktury stwardniałego zaczynu oraz uzyskanie wzrostu wartości parametrów mechanicznych. Opracowana grupa receptur może być stosowana do uszczelniania w strefie niskich ciśnień złożowych w warunkach temperatury około 30°C i w ciśnieniu około 3 MPa.
EN
In the technology of sealing casing columns in a borehole, sometimes it is necessary to use cement slurry with reduced density. This occurs most often during sealing of the borehole in the low reservoir pressure zone. To design lightweight cement slurry, an addition of filler material is used, the density of which is much lower than the density of cement. However, the presence of such an additive in the structure of fresh cement slurry may sometimes cause destabilization of the system manifested by excessive fractionation, as a result of which light particles migrate to the upper parts of the cement slurry and heavy cement grains sink to the bottom. In addition, cement slurries containing light additives also show reduced values of mechanical parameters, greater porosity and capacity for gas migration, which may disqualify a given cement slurry for use in borehole conditions. In order to eliminate these adverse changes occurring in the structure of both fresh and hardened lightweight cement slurry, admixtures are used to significantly improve the technological parameters of the designed recipe. Appropriate selection, both quantitative and qualitative, of selected agents makes it possible to eliminate the cement slurry fractionation, as a result of which it is possible to obtain a homogeneous structure of the fresh cement slurry, and the cement sheath formed after setting will demonstrate the isotropic properties of the tested mechanical parameters. In addition, additives and low molecular weight admixtures allow sealing of the cement sheath matrix in such a way that the compressive strength is significantly improved and the value of permeability and porosity is reduced. The article discusses the results of research on the development of lightweight cement slurry recipes intended for scaling of openings in the zone of low reservoir pressures. As a control sample, a recipe was selected that had been used in well conditions. This cement slurry was selected for modification due to the lack of sedimentation stability. The following recipes contained various amounts of filling materials. As light additives, filter perlite, aluminosilicate microsphere and glass microsphere were used. However, two forms of silica were used to improve sedimentation stability and obtain appropriate mechanical parameters: a colloidal sodium silicate solution and hydrophilic nanosilica. The designed cement slurry recipes were characterized by appropriate technological parameters and sedimentation stability. The modifications introduced to the cement slurries allowed to achieve a homogeneous microstructure of the hardened cement slurry and an increase in the value of mechanical parameters was obtained. The developed group of recipes can be used to seal openings in the low reservoir pressure zone at a temperature of about 30°C and a pressure of about 3 MPa.
EN
Due to present-day challenges for the improvement of the operating characteristics of rotating electrical machines, the core material is regarded as increasingly important. Non-oriented (NO) electrical steel sheets are conventionally used for the construction of magnetic cores of rotating electrical machines. The most appropriate choice of material and machine design is based on standardized material data obtained from Epstein frames or single sheet testers. Both, low losses as well as good magnetizability in any spatial direction of the sheet plane are requested. Despite their name, NO electrical steels do show a magnetic anisotropy. A significant increase of loss and decrease of permeability can additionally be induced by mechanical cutting processes to shape the magnetic circuit. Magnetic anisotropy and induced mechanical stress can affect the local iron-loss distribution, magnetizability, acoustic behavior and therefore, have to be considered in numerical simulations of electrical machines. In this paper, the interdependency of the magnetic anisotropy with the effect of cutting is studied in order to improve the necessary understanding of the material behavior.
PL
W procesie mechanicznego cięcia blchy elektrotechnicznej mogą ulec degradacji podstawowe jej parametry – straty I przenikalność. Indukowane w procesie cięcia naprężenia wpływają na anizotropię I rozkład strumienia. W artykule W artykule analizowany jest wpływ procesu cięcia na właściwości niezorientowanych blach elektrotechnicznych.
EN
In this paper authors described rate of aging behavior processes for upper leather materials, which were measured by changes of rheological properties during determination of extension set. Upper leather samples were exposed to UV rays for 100 and 150 hours in Q-SUN XenonTest Chamber, which was used to induce property changes associated with the effects of sunlight. Then, the samples have been subjected to mechanical test –determination of extension set due to PN-EN ISO 17236:2005 standard. The main goal of this analysis was to determine of UV aging resistance of these materials. The highest resistance was observed for full grain bovine leather and nubuck as the opposition to box calfs.
PL
Oceniono wpływ procesów starzenia wierzchnich skórzanych materiałów obuwniczych na zmianę ich właściwości reologicznych przy odkształceniu typu relaksacyjnego. Próbki wierzchnich skór obuwniczych naświetlano przez 100 i 150 h w symulatorze procesu przyśpieszonego starzenia ­Q-SUN Xenon Test Chamber. Oznaczano wydłużenie trwałe naświetlonych próbek według normy ­PN-EN ISO 17236:2005 i na tej podstawie oceniono ich odporność na starzenie powodowane oddziaływaniem promieniowania UV. Największą odporność wykazywały skóry welurowe oraz nubuk, natomiast najmniejszą – boksy bydlęce.
EN
The present investigation deals with the propagation of circular crested Lamb waves in a homogeneous micropolar transversely isotropic medium. Secular equations for symmetric and skew-symmetric modes of wave propagation in completely separate terms are derived. The amplitudes of displacements and microrotation are computed numerically for magnesium as a material and the dispersion curves, amplitudes of displacements and microrotation for symmetric and skew-symmetric wave modes are presented graphically to evince the effect of anisotropy. Some special cases of interest are also deduced.
EN
A numerical method of quasiconformal mappings for solving the coefficient problems of finding eigenvalues of the conductivity tensor having information about its directions in an anisotropic medium using applied quasipotential tomographic data is generalized. The corresponding algorithm is based on the alternate solving of problems on quasiconformal mappings and parameter identification. The results of numerical experiments of imitative restoration of environment structure are presented.
PL
Opracowano uogólnioną numeryczną metodę mapowania quasi-formalnego w celu rozwiązania zadań znalezienia wartości własnych tensora przewodnictwa posiadając informacje o jego kierunkach w ośrodku anizotropowym z zastosowaniem quasipotencjalnych danych tomograficznych. Podstawą algorytmu jest alternatywne rozwiązanie problemów związanych z mapowaniem quasi-formalnym i identyfikacją parametrów. Przedstawiono wyniki numerycznych symulacji odtworzenia struktury ośrodka.
EN
Fluid substitution plays the key role in reservoir characterization, leading to enhance understanding of the influence of fluids on seismic parameters. In general, fluid substitution tool assumes that the Earth is as an isotropic medium, which may not represent the practical field situation. Nevertheless, anisotropic fluid substitution provides important insights into the processes that control the anisotropic seismic response of a fractured rock when subjected to CO2 injection for enhanced oil recovery and its geological sequestration. Here, we examine the influence of fluid substitution in a porous yet fractured reservoir for quantitative interpretation of seismic data. This investigation involves anisotropic Gassmann’s equation and linear slip theory for fluid substitution in a transversely isotropic media with a horizontal axis of symmetry (HTI). We present a synthetic case by conceptualizing a double-layered half-space model with upper layer as shale and bottom layer as HTI sandstone, representing an Indian mature reservoir. The effects of variation in background porosity and fracture weaknesses on anisotropic (Thomsen’s) parameters, acoustic parameters including amplitude variation with angle have also been discussed. We observe that brine and oil sands to be associated with the highest elastic moduli, while CO2 sands exhibit contrasting trend. It is noteworthy that CO2 is more sensitive to fracture weakness when compared to the other reservoir fluids such as hydrocarbons and brines, as P-wave moduli (as much as 37.1%) and velocity (as high as 12.2%) reduces significantly with the increase in fracture weakness. Further, Gassmann’s assumption is validated as we noticed unchanged values in shear-wave moduli and shear-wave splitting parameter (γ) for various fluid types.
EN
Soft and hard interbedded rocks show obvious time-dependent deformation after deep tunnel excavations, and it is therefore necessary to research the mechanical behavior of the layered rock. However, it is hard to obtain ideal transversely isotropic rocks in fields, so rock-like specimens were poured by using artificial materials. Cyclic loading–unloading creep experiments were performed on the artificial layered cemented specimens with various layer angles (0°, 30°, 60° and 90°) at a 20 MPa confinement. Time-independent deformations and time-dependent deformations of the rock-like specimens were distinguished to investigate the visco-elasto-plastic deformation characteristics. Instantaneous elastic strain and instantaneous plastic strain had linear correlations with stress ratio, whereas creep strain, including visco-elastic strain and visco-plastic strain, increased nonlinearly with an increasing stress ratio. The specimens with a small layer angle had more noticeable time-independent and time-dependent deformations and larger steady-state creep rates than those of the specimens with a large layer angle. Attenuation creep and secondary creep could be observed at relative low stress levels, whereas accelerating creep until failure occurred at the creep failure stress level. The time for creep failure can be predicated according to the axial steady-state creep rate or volumetric creep curve. Damage in the rock-like specimens showed linear correlation with the stress ratio. Dip angle has a significant effect on the creep failure mode under cyclic loading–unloading conditions.
PL
Artykuł zawiera wyniki symulacji numerycznych metodą elementów skończonych procesu formowania wytłoczek cylindrycznych z wykorzystaniem metody jawnej (explicit) całkowania równań ruchu w warunkach kontaktu z tarciem izotropowym i anizotropowym. Przedstawiono wyniki eksperymentalne oraz numeryczne uzyskane w programie Abaqus 6.14-5. Celem badań eksperymentalnych była analiza płynięcia materiału pod wpływem zadawanych obciążeń. Wyniki te wykorzystano do weryfikacji wyników symulacji numerycznych. Stwierdzono, że chociaż anizotropia oporów tarcia decyduje o wysokości występów na krawędzi wytłoczki, wpływ warunków tarcia na ostateczny kształt wytłoczki i rozkład grubości ścianki jest stosunkowo niewielki w porównaniu z wpływem anizotropii materiałowej. Badania wykazały również, że analiza numeryczna uwzględniająca dyskretyzację blachy za pomocą 3-węzłowych trójkątnych elementów typu shell S3R zapewnia najlepsze przybliżenie wyników symulacyjnych do danych eksperymentalnych, gdy uwzględnia się w modelu numerycznym jednocześnie anizotropię materiałową oraz anizotropię oporów tarcia.
EN
This article presents the results of FEM (finite element method) numerical simulations of forming cylindrical drawpieces using the explicit integration procedure in the presence of contact conditions with isotropic and anisotropic friction. The experimental and numerical results obtained in the Abaqus 6.14-5 program are presented. The aimof the experimental research was to analyse material flow in the forming process. These results were used to verify the results of numerical simulations. It has been found that although frictional resistance anisotropy determines the height of the ears of a drawpiece, the influence of the frictional conditions on the final shape of the drawpiece and wall thickness distribution is relatively small compared to the effect of material anisotropy. The research has also shown that numerical analysis with the workpiece discretised by 3-node triangular shell elements S3R provides the best approximation of simulation results to experimental data in the conditions when numerical anisotropy and anisotropy of frictional resistance are included in the numerical model.
11
Content available remote Anizotropia stratności wybranych blach elektrotechnicznych
PL
W artykule wykazano wpływ anizotropii na właściwości blach elektrotechnicznych Przedstawiono prosty model matematyczny umożliwiający wyznaczenie stratności dla dowolnego kierunku wycięcia próbki. Model zweryfikowano wykorzystując dane pomiarowe dla wybranych gatunków blach.
EN
In the paper the influence of anisotropy on properties of electrical steel sheets is proven. A simple mathematical model, which makes it possible to determine the angular dependence of loss density, is described. The model has been verified using measurement data for chosen steel sheets.
EN
A two-scale asymptotic analysis coupled with the spatially periodic fundamental solutions are used for analyzing diffraction of elastic bulk waves propagating in anisotropic media containing periodic inclusions or voids. Explicit equations are derived for the scattering cross sections and velocities of bulk waves propagating in spatially periodic media with arbitrary elastic anisotropy.
13
Content available remote Boundary element modeling of pyroelectric solids with shell inclusions
EN
The paper presents general boundary element approach for analysis of thermoelectroelastic (pyroelectric) solids containing shell-like electricity conducting permittive inclusions. The latter are modeled with opened surfaces with certain boundary conditions on their faces. Rigid displacement and rotation, along with constant electric potential of inclusions are accounted for in these boundary conditions. Formulated boundary value problem is reduced to a system of singular boundary integral equations, which is solved numerically by the boundary element method. Special attention is paid to the field singularity at the front line of a shell-like inclusion. Special shape functions are introduced, which account for this square-root singularity and allow accurate determination of field intensity factors. Numerical examples are presented.
EN
Hydromechanical deep drawing (HMDD) is a sheet hydroforming process to produce complex workpieces with high drawing ratio. Fluid pressure used during the forming process is one of the most effective parameters in this process in which increasing critical pressure causes to rupture occurrence. Since the material properties in different angles respect to the rolling direction affect the amount of critical pressure, it is important to develop an appropriate theoretical model for prediction of plastic behavior of material with high precision. In this paper, a theoretical model based on BBC2008 yield criterion including 8 and 16 parameters (8p and 16p) is developed to determine critical pressure in HMDD process. With applying uniaxial and equi-biaxial tensile tests and optimizing an error-function by using Levenberg–Marquardt method, the parameters of BBC2008 yield criterion can be determined. Low carbon St14 steel sheets are utilized for experimental samples to verify critical pressure obtained from the proposed theoretical model. BBC2008 model with 8p and 16p is compared with Barlat–Lian 1989 and experiments. The results show that BBC2008-16p yield criterion can provide a more precise model of material behavior in planar anisotropy properties, while BBC2008-8p yield criterion have a better prediction of rupture occurrence in HMDD process.
EN
Azimuthally averaged power spectra are widely used in the Curie point depth (CPD) estimation with the implicit assumption that the magnetization distribution is random and uncorrelated. However, the marine magnetic anomalies are caused by bands of normal and reverse magnetization and show obvious trends. To investigate the effects of the anisotropy of marine magnetic anomalies on the CPD estimates, we develop 3D fractal striped magnetization models to produce lineated marine magnetic anomalies for the first time. We analyze the spectra anisotropy of the lineated magnetic anomalies of the synthetic fractal striped magnetization models and investigate its effects on the CPD estimates. The synthetic models and actual data show that the spectra of the lineated marine magnetic anomalies are directionally anisotropic. The amplitude response is strong and the slope of the logarithmic spectrum is large in a direction perpendicular to the stripes of magnetic anomalies, whereas the amplitude response is weak and the slope of the logarithmic spectrum is small in a direction parallel to the stripes of magnetic anomalies. The depth estimates in the perpendicular direction are close to the actual values, whereas the depths estimates in the parallel direction are significantly lower than the actual values. The actual marine magnetic anomalies of the South China Sea exhibit an anisotropic power spectrum that is consistent with the spectral anisotropy of magnetic anomalies of the synthetic fractal striped magnetization models.
EN
This work presents a mathematical modelling of Love wave transference through a pre-stress influenced anisotropic medium with heterogeneity between a sandy medium and an initially stressed anisotropic porous medium. Variable separation method has been induced in order to derive the frequency relation. Using appropriate boundary conditions at two interfaces, the dispersion equation has been obtained in its closed form. Possible particular cases are considered, and the corresponding results are consonant with the classical cases. Numerical computations have been employed to demonstrate the role of inhomogeneity factors, initial stresses and porosity, and are depicted by means of graphs which substantiates that those parameters immensely affect the Love wave velocity. In mineral prospecting and exploring technique in earth, the method and the results of this problem may be applicable.
EN
Lipid-protein systems paly curtail roles in living systems [49]. Hence, a determination of their structure at different levels of organization is still one of the most important tasks in many research projects. A study of lipid-protein systems is based on many physicochemical techniques, such as spectroscopy of FTIR, Raman, fluorescence, NMR, EPR, as well as DLS, DSC and TEM methods. In the presented paper tow of the most frequently used methods, that is FTIR and fluorescence spectroscopy, will be discussed in details. They are characterized by a relatively low cost of sample preparation, a short measuring time, and they give a huge number of structural and physicochemical information about lipid-protein systems. In the FTIR-ATR spectroscopy many of vibrational bands are commonly used as very precise vibrational indicators of structural changes in lipids and proteins (Fig. 1) [1–6]. They allows to characterize lipid and protein components separately in mixed systems. Additionally, structural changes in lipid membranes can be monitored in one FTIR-ATR experiment simultaneously in a region of hydrophilic lipid head-groups (Fig. 5) [17, 18], in a hydrophobic part composed of hydrocarbon lipid chains (see Figures 2 and 3) [7–9], and in a lipid membrane interface represented by ester lipid groups (Fig. 4) [4, 6, 11, 12]. A secondary structure of proteins and peptides in different experimental conditions can be defined in the FTIR-ATR spectroscopy on the base of amide I bands (Fig. 6 and Tabs 1, 2 and 3) [20–22]. A fluorescence spectroscopy is a complementary methods to FTIR spectroscopy in a study of lipid-protein systems. It competes information about time-dependent and very fast (in a scale of femtoseconds) structural processes in both lipids [41–45] and proteins [23, 27, 48]. The folding, denaturation, and aggregation of proteins and lipid membranes accompanied by changes in an order, packing and hydration of the system under study [23, 27, 41–45, 48].
18
Content available Green tensor in material sciences
EN
Material properties of heterogeneous nanomaterials modelled by effective medium approximation (EMA) demand specific approaches when metallic inclusions in a host medium are exposed to external magnetic field. Resulting induced anisotropy of permittivity is manifested itself by a specific form of polarizability tensor. In presented work, this one is applied in the so called “strong-couple-dipole” (SCD) method, where the electromagnetic Green tensor is of key importance. The results are oriented to the magneto-plasmonic sensor element design for the use in biology or chemistry.
CS
Modelování materiálových vlastnosti heterogenních nanomateriálu metodou aproximace efektivním prostredím (EMA) vyžaduje specifický prístup, jsou-li kovové cástice v obklopujícím prostredí vystaveny magnetickému poli. Výsledná indukovaná anizotropie permitivity se projevuje specifickou formou tenzoru polarizovatelnosti. Ten je v této práci aplikován prostrednictvím tzv. metody silne vázaných dipólu (SCD), kde se klícovým zpusobem uplatnuje Greenuv (elektromagnetický) tenzor. Výsledky smerují k návrhu magneto-plasmonického senzoru s užitím v bilogii a chemii.
EN
This paper presents experimental data measured up to 2T under rotational circular flux density. The results show that at lower excitations there is significant anisotropy of permeability. However at 2T the anisotropy collapses so that the permeability varies only ±14% from the average value. On a qualitative level the results are very similar to the directional curves for single-crystal samples for the three significant crystallographic directions [100], [110] and [111] shown previously in the literature.
PL
Artykuł prezentuje dane eksperymentalne do amplitudy 2 T przy przemangesowaniu obrotowym kołowym. Rezultaty pokazują, że przy mniejszym wymuszeniu występuje znacząca anizotropia przenikalności. Jednak przy 2T anisotropia zanika i przenikalność zmienia się tylko o ±14% w porównaniu do wartości średniej. W ujęciu jakościowym wyniki są bardzo podobne do krzywych kierunkowych dla monokryształu dla trzech głównych kierunków [100], [110] i [111] zgodnie z poprzednimi publikacjami.
EN
In the paper results of experiments on hydrodynamic assessment of gas flow through backbone (skeletal) porous materials with an anisotropic structure are presented. The research was carried out on materials of different petrographic characteristics and origin of process (char). The study was conducted for a variety of hydrodynamic conditions with the use of air. As the basis for the hydrodynamics of gas flow through porous material we assumed a gas stream as a result of pressure forcing such flow. The results of measurements indicate a clear effect of the type of material on the gas permeability, and additionally - as a result of their anisotropic internal structure - a significant effect of the flow direction on the value of gas stream.
PL
W pracy przedstawiono wyniki badań doświadczalnych w zakresie oceny hydrodynamiki przepływu gazu przez sztywne (szkieletowe) materiały porowate o anizotropowej strukturze. Badania odniesiono do materiałów o zróżnicowanej charakterystyce petrograficznej, pochodzenia procesu termicznego (karbonizaty). Badania prowadzono dla różnych warunków hydrodynamicznych z wykorzystaniem powietrza. Za podstawę oceny hydrodynamiki przepływu gazu przez złoża i materiały porowate przyjęto strumień gazu, jaki wynika z nadciśnienia wymuszającego ten przepływ. Wyniki pomiarów wskazują na wyraźny wpływ rodzaju materiału na gazoprzepuszczalność, a dodatkowo – co wynika z ich anizotropowej struktury wewnętrznej - na wyraźny wpływ kierunkowości przepływu na wartość strumienia gazu.
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